From 0392538775f9590ef9b977ed11f51b1e5dbd8adf Mon Sep 17 00:00:00 2001
From: Pinaki Poddar <ppoddar@apache.org>
Date: Tue, 5 May 2009 18:03:31 +0000
Subject: [PATCH] OPENJPA-1013,OPENJPA-1014: Type-strict Criteria API
 (skeletal) implementation as per JPA 2.0.

git-svn-id: https://svn.apache.org/repos/asf/openjpa/trunk@771948 13f79535-47bb-0310-9956-ffa450edef68
---
 .../kernel/jpql/JPQLExpressionBuilder.java    |  89 ++-
 .../openjpa/persistence/criteria/Account.java |   3 +
 .../persistence/criteria/Account_.java        |  37 +
 .../criteria/TestTypesafeCriteria.java        | 149 ++++
 .../persistence/EntityManagerFactoryImpl.java |   3 +-
 .../persistence/EntityManagerImpl.java        |   5 +-
 .../openjpa/persistence/ResultItemImpl.java   |  49 ++
 .../persistence/criteria/CriteriaBuilder.java | 675 ++++++++++++++++
 .../criteria/CriteriaQueryImpl.java           | 218 ++++++
 .../persistence/criteria/ExpressionImpl.java  |  91 +++
 .../persistence/criteria/Expressions.java     | 724 ++++++++++++++++++
 .../persistence/criteria/FromImpl.java        | 248 ++++++
 .../persistence/criteria/OrderImpl.java       |  54 ++
 .../persistence/criteria/ParameterImpl.java   |  51 ++
 .../persistence/criteria/PathImpl.java        | 114 +++
 .../persistence/criteria/PredicateImpl.java   | 125 +++
 .../persistence/criteria/RootImpl.java        |  45 ++
 .../persistence/criteria/SelectionImpl.java   |  38 +
 ...pache.openjpa.kernel.exps.ExpressionParser |  17 +
 19 files changed, 2694 insertions(+), 41 deletions(-)
 create mode 100644 openjpa-persistence-jdbc/src/test/java/org/apache/openjpa/persistence/criteria/Account_.java
 create mode 100644 openjpa-persistence-jdbc/src/test/java/org/apache/openjpa/persistence/criteria/TestTypesafeCriteria.java
 create mode 100644 openjpa-persistence/src/main/java/org/apache/openjpa/persistence/ResultItemImpl.java
 create mode 100644 openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/CriteriaBuilder.java
 create mode 100644 openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/CriteriaQueryImpl.java
 create mode 100644 openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/ExpressionImpl.java
 create mode 100644 openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/Expressions.java
 create mode 100644 openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/FromImpl.java
 create mode 100644 openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/OrderImpl.java
 create mode 100644 openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/ParameterImpl.java
 create mode 100644 openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/PathImpl.java
 create mode 100644 openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/PredicateImpl.java
 create mode 100644 openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/RootImpl.java
 create mode 100644 openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/SelectionImpl.java
 create mode 100644 openjpa-persistence/src/main/resources/META-INF/services/org.apache.openjpa.kernel.exps.ExpressionParser

diff --git a/openjpa-kernel/src/main/java/org/apache/openjpa/kernel/jpql/JPQLExpressionBuilder.java b/openjpa-kernel/src/main/java/org/apache/openjpa/kernel/jpql/JPQLExpressionBuilder.java
index 12c937166..c803a983a 100644
--- a/openjpa-kernel/src/main/java/org/apache/openjpa/kernel/jpql/JPQLExpressionBuilder.java
+++ b/openjpa-kernel/src/main/java/org/apache/openjpa/kernel/jpql/JPQLExpressionBuilder.java
@@ -1091,43 +1091,7 @@ public class JPQLExpressionBuilder
                 if (node.children.length == 3)
                     setImplicitType(val3, Integer.TYPE);
 
-                // the semantics of the JPQL substring() function
-                // are that arg2 is the 1-based start index, and arg3 is
-                // the length of the string to be return; this is different
-                // than the semantics of the ExpressionFactory's substring,
-                // which matches the Java language (0-based start index,
-                // arg2 is the end index): we perform the translation by
-                // adding one to the first argument, and then adding the
-                // first argument to the second argument to get the endIndex
-                Value start = null;
-                Value end = null;
-                if (val2 instanceof Literal && 
-                    (val3 == null || val3 instanceof Literal)) {
-                    // optimize SQL for the common case of two literals
-                    long jpqlStart = ((Number) ((Literal) val2).getValue())
-                        .longValue();
-                    start = factory.newLiteral(new Long(jpqlStart - 1),
-                        Literal.TYPE_NUMBER);
-                    if (val3 != null) {
-                    	long length = ((Number) ((Literal) val3).getValue())
-                            .longValue();
-                    long endIndex = length + (jpqlStart - 1);
-                    end = factory.newLiteral(new Long(endIndex),
-                        Literal.TYPE_NUMBER);
-                    }
-                } else {
-                    start = factory.subtract(val2, factory.newLiteral
-                        (Numbers.valueOf(1), Literal.TYPE_NUMBER));
-                    if (val3 != null)
-                    end = factory.add(val3,
-                        (factory.subtract(val2, factory.newLiteral
-                            (Numbers.valueOf(1), Literal.TYPE_NUMBER))));
-                }
-                if (val3 != null)
-                return factory.substring(val1, factory.newArgumentList(
-                    start, end));
-                else
-                    return factory.substring(val1, start);
+                return convertSubstringArguments(factory, val1, val2, val3);
 
             case JJTLOCATE:
                 // as with SUBSTRING (above), the semantics for LOCATE differ
@@ -1220,7 +1184,56 @@ public class JPQLExpressionBuilder
                     new Object[]{ node }, null);
         }
     }
-
+    
+    /**
+     * Converts JPQL substring() function to OpenJPA ExpressionFactory 
+     * substring() arguments.
+     * 
+     * The semantics of the JPQL substring() function are that arg2 is the 
+     * 1-based start index, and arg3 is the length of the string to be return.
+     * This is different than the semantics of the ExpressionFactory's 
+     * substring(), which matches the Java language (0-based start index,
+     * arg2 is the end index): we perform the translation by adding one to the 
+     * first argument, and then adding the first argument to the second  
+     * argument to get the endIndex.
+     * 
+     * @param val1 the original String
+     * @param val2 the 1-based start index as per JPQL substring() semantics
+     * @param val3 the length of the returned string as per JPQL semantics
+     * 
+     */
+    public static Value convertSubstringArguments(ExpressionFactory factory, 
+    		Value val1, Value val2, Value val3) {
+        Value start = null;
+        Value end = null;
+        if (val2 instanceof Literal && 
+            (val3 == null || val3 instanceof Literal)) {
+            // optimize SQL for the common case of two literals
+            long jpqlStart = ((Number) ((Literal) val2).getValue())
+                .longValue();
+            start = factory.newLiteral(new Long(jpqlStart - 1),
+                Literal.TYPE_NUMBER);
+            if (val3 != null) {
+            	long length = ((Number) ((Literal) val3).getValue())
+                    .longValue();
+            long endIndex = length + (jpqlStart - 1);
+            end = factory.newLiteral(new Long(endIndex),
+                Literal.TYPE_NUMBER);
+            }
+        } else {
+            start = factory.subtract(val2, factory.newLiteral
+                (Numbers.valueOf(1), Literal.TYPE_NUMBER));
+            if (val3 != null)
+            end = factory.add(val3,
+                (factory.subtract(val2, factory.newLiteral
+                    (Numbers.valueOf(1), Literal.TYPE_NUMBER))));
+        }
+        if (val3 != null)
+            return factory.substring(val1, factory.newArgumentList(start, end));
+        else
+            return factory.substring(val1, start);
+    	
+    }
     private void assertQueryExtensions(String clause) {
         OpenJPAConfiguration conf = resolver.getConfiguration();
         switch(conf.getCompatibilityInstance().getJPQL()) {
diff --git a/openjpa-persistence-jdbc/src/test/java/org/apache/openjpa/persistence/criteria/Account.java b/openjpa-persistence-jdbc/src/test/java/org/apache/openjpa/persistence/criteria/Account.java
index 782fa5b8e..92851704a 100644
--- a/openjpa-persistence-jdbc/src/test/java/org/apache/openjpa/persistence/criteria/Account.java
+++ b/openjpa-persistence-jdbc/src/test/java/org/apache/openjpa/persistence/criteria/Account.java
@@ -37,4 +37,7 @@ public class Account {
 	private long id;
 	
 	private int balance;
+	private Integer loan;
+	private String owner;
+	private String name;
 }
diff --git a/openjpa-persistence-jdbc/src/test/java/org/apache/openjpa/persistence/criteria/Account_.java b/openjpa-persistence-jdbc/src/test/java/org/apache/openjpa/persistence/criteria/Account_.java
new file mode 100644
index 000000000..352fca083
--- /dev/null
+++ b/openjpa-persistence-jdbc/src/test/java/org/apache/openjpa/persistence/criteria/Account_.java
@@ -0,0 +1,37 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.    
+ */
+package org.apache.openjpa.persistence.criteria;
+
+import javax.persistence.metamodel.Attribute;
+
+/**
+ * This source is supposed to be automatically generated from Account.java
+ * during compilation.
+ * Hand coded to avoid runtime compiler invocation. Used for testing.
+ * 
+ * @author Pinaki Poddar
+ *
+ */
+public class Account_ {
+	public static volatile Attribute<Account, Long> id;
+	public static volatile Attribute<Account, Integer> balance;
+	public static volatile Attribute<Account, Integer> loan;
+	public static volatile Attribute<Account, String> owner;
+	public static volatile Attribute<Account, String> name;
+}
diff --git a/openjpa-persistence-jdbc/src/test/java/org/apache/openjpa/persistence/criteria/TestTypesafeCriteria.java b/openjpa-persistence-jdbc/src/test/java/org/apache/openjpa/persistence/criteria/TestTypesafeCriteria.java
new file mode 100644
index 000000000..ff0c0bdec
--- /dev/null
+++ b/openjpa-persistence-jdbc/src/test/java/org/apache/openjpa/persistence/criteria/TestTypesafeCriteria.java
@@ -0,0 +1,149 @@
+package org.apache.openjpa.persistence.criteria;
+
+import java.util.List;
+
+import javax.persistence.EntityManager;
+import javax.persistence.criteria.CriteriaQuery;
+import javax.persistence.criteria.Root;
+
+import org.apache.openjpa.jdbc.conf.JDBCConfiguration;
+import org.apache.openjpa.jdbc.sql.DBDictionary;
+import org.apache.openjpa.persistence.test.SQLListenerTestCase;
+
+/**
+ * Tests type-strict version of Criteria API.
+ * 
+ * Most of the tests build Criteria Query and then execute the query as well
+ * as a reference JPQL query supplied as a string. The test is validated by
+ * asserting that the resultant SQL queries for these two alternative form
+ * of executing a query are the same.
+ * 
+ * 
+ *  
+ * @author Pinaki Poddar
+ *
+ */
+public class TestTypesafeCriteria extends SQLListenerTestCase {
+    CriteriaBuilder cb;
+    EntityManager em;
+    
+    public void setUp() {
+        super.setUp(Account.class);
+        setDictionary();
+        cb = (CriteriaBuilder)emf.getQueryBuilder();
+        em = emf.createEntityManager();
+    }
+    
+    void setDictionary() {
+    	JDBCConfiguration conf = (JDBCConfiguration)emf.getConfiguration();
+    	DBDictionary dict = conf.getDBDictionaryInstance();
+    	dict.requiresCastForComparisons = false;
+    	dict.requiresCastForMathFunctions = false;
+    }
+    
+    public void testRoot() {
+    	String jpql = "select a from Account a";
+        CriteriaQuery c = cb.create();
+        Root<Account> account = c.from(Account.class);
+        c.select(account);
+        
+        assertEquivalence(c, jpql);
+    }
+    
+    public void testEqual() {
+    	String jpql = "select a from Account a where a.balance=100";
+    	
+        CriteriaQuery c = cb.create();
+        Root<Account> account = c.from(Account.class);
+        c.select(account).where(cb.equal(account.get(Account_.balance), 100));
+        
+        assertEquivalence(c, jpql);
+    }
+    
+    public void testEqual2() {
+    	String jpql = "select a from Account a where a.balance=a.loan";
+    	
+        CriteriaQuery c = cb.create();
+        Root<Account> account = c.from(Account.class);
+        c.select(account).where(cb.equal(account.get(Account_.balance), account.get(Account_.loan)));
+        
+        assertEquivalence(c, jpql);
+    }
+    
+    public void testProj() {
+    	String jpql = "select a.balance,a.loan from Account a";
+        CriteriaQuery c = cb.create();
+        Root<Account> account = c.from(Account.class);
+        c.select(account.get(Account_.balance), account.get(Account_.loan));
+        assertEquivalence(c, jpql);
+        
+    }
+
+    
+    public void testAbs() {
+        CriteriaQuery c = cb.create();
+        Root<Account> account = c.from(Account.class);
+        
+    	String jpql = "select a from Account a where abs(a.balance)=100";
+        c.select(account).where(cb.equal(cb.abs(account.get(Account_.balance)), 100));
+        assertEquivalence(c, jpql);
+    }
+    
+    public void testAvg() {
+        CriteriaQuery c = cb.create();
+        Root<Account> account = c.from(Account.class);
+        
+    	String jpql = "select avg(a.balance) from Account a";
+        c.select(cb.avg(account.get(Account_.balance)));
+        assertEquivalence(c, jpql);
+    }
+
+    
+    public void testBinaryPredicate() {
+    	String jpql = "select a from Account a where a.balance>100 and a.balance<200";
+    	
+        CriteriaQuery c = cb.create();
+        Root<Account> account = c.from(Account.class);
+        c.select(account).where(cb.and(
+          cb.greaterThan(account.get(Account_.balance), 100),
+          cb.lessThan(account.get(Account_.balance), 200)));
+        
+        assertEquivalence(c, jpql);
+    }
+    
+    public void testUnaryExpression() {
+    	String jpql = "select a from Account a where a.balance=abs(a.balance)";
+    	
+        CriteriaQuery c = cb.create();
+        Root<Account> account = c.from(Account.class);
+        c.select(account).where(cb.equal(account.get(Account_.balance), cb.abs(account.get(Account_.balance))));
+        
+        assertEquivalence(c, jpql);
+    }
+    
+    public void testBetweenExpression() {
+    	String jpql = "select a from Account a where a.balance between 100 and 200";
+    	
+        CriteriaQuery c = cb.create();
+        Root<Account> account = c.from(Account.class);
+        c.select(account).where(cb.between(account.get(Account_.balance), 100, 200));
+        
+        assertEquivalence(c, jpql);
+    }
+
+    
+    
+    void assertEquivalence(CriteriaQuery c, String jpql) {
+    	sql.clear();
+    	List cList = em.createQuery(c).getResultList();
+    	assertEquals(1, sql.size());
+    	String cSQL = sql.get(0);
+    	
+    	sql.clear();
+    	List jList = em.createQuery(jpql).getResultList();
+    	assertEquals(1, sql.size());
+    	String jSQL = sql.get(0);
+    	
+    	assertEquals(jSQL, cSQL);
+    }
+}
diff --git a/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/EntityManagerFactoryImpl.java b/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/EntityManagerFactoryImpl.java
index c5308ddaa..a41b25c42 100644
--- a/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/EntityManagerFactoryImpl.java
+++ b/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/EntityManagerFactoryImpl.java
@@ -47,6 +47,7 @@ import org.apache.openjpa.lib.conf.Value;
 import org.apache.openjpa.lib.util.Localizer;
 import org.apache.openjpa.lib.util.Closeable;
 import org.apache.openjpa.meta.MetaDataRepository;
+import org.apache.openjpa.persistence.criteria.CriteriaBuilder;
 import org.apache.openjpa.persistence.meta.MetamodelImpl;
 import org.apache.openjpa.persistence.query.OpenJPAQueryBuilder;
 import org.apache.openjpa.persistence.query.QueryBuilderImpl;
@@ -357,7 +358,7 @@ public class EntityManagerFactoryImpl
     }
 
     public QueryBuilder getQueryBuilder() {
-        throw new UnsupportedOperationException();
+        return new CriteriaBuilder().setMetaModel(getMetamodel());
     }
     
     public OpenJPAQueryBuilder getDynamicQueryBuilder() {
diff --git a/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/EntityManagerImpl.java b/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/EntityManagerImpl.java
index a4beb1680..2e53cff4c 100644
--- a/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/EntityManagerImpl.java
+++ b/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/EntityManagerImpl.java
@@ -70,6 +70,7 @@ import org.apache.openjpa.meta.ClassMetaData;
 import org.apache.openjpa.meta.FieldMetaData;
 import org.apache.openjpa.meta.QueryMetaData;
 import org.apache.openjpa.meta.SequenceMetaData;
+import org.apache.openjpa.persistence.criteria.CriteriaBuilder;
 import org.apache.openjpa.util.Exceptions;
 import org.apache.openjpa.util.ImplHelper;
 import org.apache.openjpa.util.RuntimeExceptionTranslator;
@@ -1509,8 +1510,8 @@ public class EntityManagerImpl
     }
 
     public Query createQuery(CriteriaQuery criteriaQuery) {
-        throw new UnsupportedOperationException(
-        "JPA 2.0 - Method not yet implemented");
+        return new QueryImpl(this, _ret, 
+            _broker.newQuery(CriteriaBuilder.LANG_CRITERIA, criteriaQuery));
     }
     
     public OpenJPAQuery createDynamicQuery(
diff --git a/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/ResultItemImpl.java b/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/ResultItemImpl.java
new file mode 100644
index 000000000..7886be113
--- /dev/null
+++ b/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/ResultItemImpl.java
@@ -0,0 +1,49 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.openjpa.persistence;
+
+import javax.persistence.ResultItem;
+
+/**
+ * A single dimension of projection in query result.
+ * 
+ * @author Pinaki Poddar
+ *
+ * @param <X> type of the result
+ */
+public class ResultItemImpl<X> implements ResultItem<X> {
+    protected String _alias;
+    protected Class<X> _cls;
+    
+    protected ResultItemImpl(Class<X> cls) {
+        _cls = cls;
+    }
+    
+    public String getAlias() {
+        return _alias;
+    }
+
+    public void setAlias(String alias) {
+        _alias = alias;
+    }
+
+    public Class<X> getJavaType() {
+        return _cls;
+    }
+}
diff --git a/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/CriteriaBuilder.java b/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/CriteriaBuilder.java
new file mode 100644
index 000000000..f67152f76
--- /dev/null
+++ b/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/CriteriaBuilder.java
@@ -0,0 +1,675 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.    
+ */
+package org.apache.openjpa.persistence.criteria;
+
+import java.math.BigDecimal;
+import java.math.BigInteger;
+import java.sql.Date;
+import java.sql.Time;
+import java.sql.Timestamp;
+import java.util.Collection;
+import java.util.Map;
+import java.util.Set;
+
+import javax.persistence.Parameter;
+import javax.persistence.criteria.CriteriaQuery;
+import javax.persistence.criteria.Expression;
+import javax.persistence.criteria.Order;
+import javax.persistence.criteria.Predicate;
+import javax.persistence.criteria.QueryBuilder;
+import javax.persistence.criteria.Selection;
+import javax.persistence.criteria.Subquery;
+
+import org.apache.openjpa.kernel.ExpressionStoreQuery;
+import org.apache.openjpa.kernel.exps.ExpressionFactory;
+import org.apache.openjpa.kernel.exps.ExpressionParser;
+import org.apache.openjpa.kernel.exps.QueryExpressions;
+import org.apache.openjpa.kernel.exps.Value;
+import org.apache.openjpa.meta.ClassMetaData;
+import org.apache.openjpa.persistence.meta.MetamodelImpl;
+
+/**
+ * Factory for Criteria query expressions.
+ * 
+ * Acts as an adapter to OpenJPA ExpressionFactory.
+ * 
+ * @author Pinaki Poddar
+ * 
+ * @since 2.0.0
+ *
+ */
+@SuppressWarnings("serial")
+public class CriteriaBuilder implements QueryBuilder, ExpressionParser {
+    public static final String LANG_CRITERIA = "javax.persistence.criteria";
+
+    private MetamodelImpl _model;
+
+    public CriteriaBuilder setMetaModel(MetamodelImpl model) {
+        _model = model;
+        return this;
+    }
+
+    public QueryExpressions eval(Object parsed, ExpressionStoreQuery query,
+        ExpressionFactory factory, ClassMetaData candidate) {
+        CriteriaQueryImpl c = (CriteriaQueryImpl) parsed;
+        return c.getQueryExpressions(factory);
+    }
+    
+    public Value[] eval(String[] vals, ExpressionStoreQuery query,
+        ExpressionFactory factory, ClassMetaData candidate) {
+        throw new AbstractMethodError();
+    }
+
+    public String getLanguage() {
+        return LANG_CRITERIA;
+    }
+
+    public Object parse(String ql, ExpressionStoreQuery query) {
+        throw new AbstractMethodError();
+    }
+
+    public void populate(Object parsed, ExpressionStoreQuery query) {
+        CriteriaQueryImpl c = (CriteriaQueryImpl) parsed;
+        query.getContext().setCandidateType(c.getRoot().getJavaType(), true);
+        query.setQuery(parsed);
+    }
+
+    public <N extends Number> Expression<N> abs(Expression<N> x) {
+        return new Expressions.Abs<N>(x);
+    }
+
+    public <Y> Expression<Y> all(Subquery<Y> subquery) {
+        throw new AbstractMethodError();
+    }
+
+    public Predicate and(Predicate... restrictions) {
+    	return new PredicateImpl.And(restrictions);
+    }
+
+    public Predicate and(Expression<Boolean> x, Expression<Boolean> y) {
+    	return new PredicateImpl.And(x,y);
+    }
+
+    public <Y> Expression<Y> any(Subquery<Y> subquery) {
+        throw new AbstractMethodError();
+    }
+
+    public Order asc(Expression<?> x) {
+        return new OrderImpl(x, true);
+    }
+
+    public <N extends Number> Expression<Double> avg(Expression<N> x) {
+        return new Expressions.Avg(x);
+    }
+
+    public <Y extends Comparable<Y>> Predicate between(
+        Expression<? extends Y> v, Expression<? extends Y> x,
+        Expression<? extends Y> y) {
+        return new Expressions.Between<Y>(v, x, y);
+    }
+
+    public <Y extends Comparable<Y>> Predicate between(
+        Expression<? extends Y> v, Y x, Y y) {
+        return new Expressions.Between<Y>(v,x,y);
+    }
+
+    public <T> Coalesce<T> coalesce() {
+        return new Expressions.Coalesce();
+    }
+
+    public <Y> Expression<Y> coalesce(Expression<? extends Y> x,
+        Expression<? extends Y> y) {
+    	return new Expressions.Coalesce<Y>().value(x).value(y);
+    }
+
+    public <Y> Expression<Y> coalesce(Expression<? extends Y> x, Y y) {
+    	return new Expressions.Coalesce<Y>().value(x).value(y);
+   }
+
+    public Expression<String> concat(Expression<String> x, 
+        Expression<String> y) {
+    	return new Expressions.Concat(x, y);
+    }
+
+    public Expression<String> concat(Expression<String> x, String y) {
+    	return new Expressions.Concat(x, y);
+    }
+
+    public Expression<String> concat(String x, Expression<String> y) {
+    	return new Expressions.Concat(x, y);
+    }
+
+    public Predicate conjunction() {
+        return new PredicateImpl.And();
+    }
+
+    public Expression<Long> count(Expression<?> x) {
+        return new Expressions.Count(x);
+    }
+
+    public Expression<Long> countDistinct(Expression<?> x) {
+        return new Expressions.Count(x, true);
+    }
+
+    public CriteriaQuery create() {
+        return new CriteriaQueryImpl(_model);
+    }
+
+    public Expression<Date> currentDate() {
+    	return new Expressions.CurrentDate();
+    }
+
+    public Expression<Time> currentTime() {
+    	return new Expressions.CurrentTime();
+    }
+
+    public Expression<Timestamp> currentTimestamp() {
+    	return new Expressions.CurrentTimestamp();
+    }
+
+    public Order desc(Expression<?> x) {
+    	return new OrderImpl(x, false);
+    }
+
+    public <N extends Number> Expression<N> diff(Expression<? extends N> x,
+        Expression<? extends N> y) {
+        return new Expressions.Diff<N>(x, y);
+    }
+
+    public <N extends Number> Expression<N> diff(
+        Expression<? extends N> x, N y) {
+        return new Expressions.Diff<N>(x, y);
+    }
+
+    public <N extends Number> Expression<N> diff(N x, 
+        Expression<? extends N> y) {
+        return new Expressions.Diff<N>(x, y);
+    }
+
+    public Predicate disjunction() {
+        return new PredicateImpl.Or();
+    }
+
+    public Predicate equal(Expression<?> x, Expression<?> y) {
+        return new Expressions.Equal(x, y);
+    }
+
+    public Predicate equal(Expression<?> x, Object y) {
+        return new Expressions.Equal(x, y);
+    }
+
+    public Predicate exists(Subquery<?> subquery) {
+        throw new AbstractMethodError();
+    }
+
+    public <T> Expression<T> function(String name, Class<T> type,
+        Expression<?>... args) {
+        throw new AbstractMethodError();
+    }
+
+    public Predicate ge(Expression<? extends Number> x,
+        Expression<? extends Number> y) {
+        return new Expressions.GreaterThanEqual(x,y);
+    }
+
+    public Predicate ge(Expression<? extends Number> x, Number y) {
+        return new Expressions.GreaterThanEqual(x,y);
+    }
+
+    public <Y extends Comparable<Y>> Predicate greaterThan(
+        Expression<? extends Y> x, Expression<? extends Y> y) {
+        return new Expressions.GreaterThan(x,y);
+    }
+
+    public <Y extends Comparable<Y>> Predicate greaterThan(
+        Expression<? extends Y> x, Y y) {
+        return new Expressions.GreaterThan(x, y);
+    }
+
+    public <Y extends Comparable<Y>> Predicate greaterThanOrEqualTo(
+        Expression<? extends Y> x, Expression<? extends Y> y) {
+        return new Expressions.GreaterThanEqual(x,y);
+    }
+
+    public <Y extends Comparable<Y>> Predicate greaterThanOrEqualTo(
+        Expression<? extends Y> x, Y y) {
+        return new Expressions.GreaterThanEqual(x,y);
+    }
+
+    public <X extends Comparable<X>> Expression<X> greatest(Expression<X> x) {
+    	return new Expressions.Max<X>(x);
+    }
+
+    public Predicate gt(Expression<? extends Number> x,
+        Expression<? extends Number> y) {
+        return new Expressions.GreaterThan(x,y);
+    }
+
+    public Predicate gt(Expression<? extends Number> x, Number y) {
+        return new Expressions.GreaterThan(x,y);
+    }
+
+    public <T> In<T> in(Expression<? extends T> expression) {
+        return new Expressions.In<T>(expression);
+    }
+
+    public <C extends Collection<?>> Predicate isEmpty(
+        Expression<C> collection) {
+        return new Expressions.IsEmpty(collection);
+    }
+
+    public Predicate isFalse(Expression<Boolean> x) {
+        return new Expressions.Equal(x, false);
+    }
+
+    public <E, C extends Collection<E>> Predicate isMember(E e,
+        Expression<C> c) {
+        return new Expressions.IsMember<E>(e, c);
+    }
+
+    public <E, C extends Collection<E>> Predicate isMember(Expression<E> e,
+        Expression<C> c) {
+        return new Expressions.IsMember<E>(e.getJavaType(), e, c);
+    }
+
+    public <C extends Collection<?>> Predicate isNotEmpty(
+        Expression<C> collection) {
+        return isEmpty(collection).negate();
+    }
+
+    public <E, C extends Collection<E>> Predicate isNotMember(E e,
+        Expression<C> c) {
+        return isMember(e, c).negate();
+    }
+
+    public <E, C extends Collection<E>> Predicate isNotMember(
+        Expression<E> e, Expression<C> c) {
+        return isMember(e, c).negate();
+    }
+
+    public Predicate isTrue(Expression<Boolean> x) {
+        return new Expressions.Equal(x, false);
+    }
+
+    public <K, M extends Map<K, ?>> Expression<Set<K>> keys(M map) {
+        throw new AbstractMethodError();
+    }
+
+    public Predicate le(Expression<? extends Number> x,
+        Expression<? extends Number> y) {
+        return new Expressions.LessThanEqual(x,y);
+    }
+
+    public Predicate le(Expression<? extends Number> x, Number y) {
+        return new Expressions.LessThanEqual(x,y);
+    }
+
+    public <X extends Comparable<X>> Expression<X> least(Expression<X> x) {
+        return new Expressions.Min<X>(x);
+    }
+
+    public Expression<Integer> length(Expression<String> x) {
+        throw new AbstractMethodError();
+
+    }
+
+    public <Y extends Comparable<Y>> Predicate lessThan(
+        Expression<? extends Y> x, Expression<? extends Y> y) {
+        return new Expressions.LessThan(x,y);
+    }
+
+    public <Y extends Comparable<Y>> Predicate lessThan(
+        Expression<? extends Y> x, Y y) {
+        return new Expressions.LessThan(x,y);
+
+    }
+
+    public <Y extends Comparable<Y>> Predicate lessThanOrEqualTo(
+        Expression<? extends Y> x, Expression<? extends Y> y) {
+        return new Expressions.LessThanEqual(x,y);
+    }
+
+    public <Y extends Comparable<Y>> Predicate lessThanOrEqualTo(
+        Expression<? extends Y> x, Y y) {
+        return new Expressions.LessThanEqual(x,y);
+    }
+
+    public Predicate like(Expression<String> x, Expression<String> pattern) {
+        return new Expressions.Like(x,pattern);
+    }
+
+    public Predicate like(Expression<String> x, String pattern) {
+        return new Expressions.Like(x,pattern);
+    }
+
+    public Predicate like(Expression<String> x, Expression<String> pattern,
+        Expression<Character> escapeChar) {
+        return new Expressions.Like(x,pattern,escapeChar);
+    }
+
+    public Predicate like(Expression<String> x, Expression<String> pattern,
+        char escapeChar) {
+        return new Expressions.Like(x,pattern,escapeChar);
+    }
+
+    public Predicate like(Expression<String> x, String pattern,
+        Expression<Character> escapeChar) {
+        return new Expressions.Like(x,pattern,escapeChar);
+    }
+
+    public Predicate like(Expression<String> x, String pattern, 
+        char escapeChar) {
+        return new Expressions.Like(x,pattern,escapeChar);
+    }
+
+    public <T> Expression<T> literal(T value) {
+        return new Expressions.Constant<T>(value);
+    }
+
+    public Expression<Integer> locate(Expression<String> x,
+        Expression<String> pattern) {
+        throw new AbstractMethodError();
+
+    }
+
+    public Expression<Integer> locate(Expression<String> x, String pattern) {
+        throw new AbstractMethodError();
+
+    }
+
+    public Expression<Integer> locate(Expression<String> x,
+        Expression<String> pattern, Expression<Integer> from) {
+        throw new AbstractMethodError();
+
+    }
+
+    public Expression<Integer> locate(Expression<String> x, String pattern,
+        int from) {
+        throw new AbstractMethodError();
+
+    }
+
+    public Expression<String> lower(Expression<String> x) {
+        throw new AbstractMethodError();
+
+    }
+
+    public Predicate lt(Expression<? extends Number> x,
+        Expression<? extends Number> y) {
+        return new Expressions.LessThan(x,y);
+    }
+
+    public Predicate lt(Expression<? extends Number> x, Number y) {
+        return new Expressions.LessThan(x,y);
+    }
+
+    public <N extends Number> Expression<N> max(Expression<N> x) {
+        return new Expressions.Max<N>(x);
+    }
+
+    public <N extends Number> Expression<N> min(Expression<N> x) {
+        return new Expressions.Min<N>(x);
+    }
+
+    public Expression<Integer> mod(Expression<Integer> x, 
+        Expression<Integer> y) {
+        return new Expressions.Mod(x,y);
+    }
+
+    public Expression<Integer> mod(Expression<Integer> x, Integer y) {
+        return new Expressions.Mod(x,y);
+    }
+
+    public Expression<Integer> mod(Integer x, Expression<Integer> y) {
+        return new Expressions.Mod(x,y);
+    }
+
+    public <N extends Number> Expression<N> neg(Expression<N> x) {
+        throw new AbstractMethodError();
+    }
+
+    public Predicate not(Expression<Boolean> restriction) {
+        throw new AbstractMethodError();
+    }
+
+    public Predicate notEqual(Expression<?> x, Expression<?> y) {
+        return equal(x, y).negate();
+    }
+
+    public Predicate notEqual(Expression<?> x, Object y) {
+        return equal(x, y).negate();
+    }
+
+    public Predicate notLike(Expression<String> x, Expression<String> pattern) {
+        return like(x, pattern).negate();
+    }
+
+    public Predicate notLike(Expression<String> x, String pattern) {
+        return like(x, pattern).negate();
+    }
+
+    public Predicate notLike(Expression<String> x, Expression<String> pattern,
+        Expression<Character> escapeChar) {
+        return like(x, pattern, escapeChar).negate();
+    }
+
+    public Predicate notLike(Expression<String> x, Expression<String> pattern,
+        char escapeChar) {
+        return like(x, pattern, escapeChar).negate();
+    }
+
+    public Predicate notLike(Expression<String> x, String pattern,
+        Expression<Character> escapeChar) {
+        return like(x, pattern, escapeChar).negate();
+    }
+
+    public Predicate notLike(Expression<String> x, String pattern,
+        char escapeChar) {
+        return like(x, pattern, escapeChar).negate();
+    }
+
+    public <Y> Expression<Y> nullif(Expression<Y> x, Expression<?> y) {
+        throw new AbstractMethodError();
+
+    }
+
+    public <Y> Expression<Y> nullif(Expression<Y> x, Y y) {
+        throw new AbstractMethodError();
+
+    }
+
+    public Predicate or(Predicate... restrictions) {
+        return new PredicateImpl.Or();
+    }
+
+    public Predicate or(Expression<Boolean> x, Expression<Boolean> y) {
+    	return new PredicateImpl.Or(x,y);
+    }
+
+    public <T> Parameter<T> parameter(Class<T> paramClass) {
+        return new ParameterImpl<T>(paramClass);
+    }
+
+    public <T> Parameter<T> parameter(Class<T> paramClass, String name) {
+        return new ParameterImpl<T>(paramClass).setName(name);
+    }
+
+    public <N extends Number> Expression<N> prod(Expression<? extends N> x,
+        Expression<? extends N> y) {
+        return new Expressions.Product<N>(x,y);
+    }
+
+    public <N extends Number> Expression<N> prod(Expression<? extends N> x, 
+    	N y) {
+        return new Expressions.Product<N>(x,y);
+    }
+
+    public <N extends Number> Expression<N> prod(N x, 
+        Expression<? extends N> y) {
+        return new Expressions.Product<N>(x,y);
+    }
+
+    public Expression<Number> quot(Expression<? extends Number> x,
+        Expression<? extends Number> y) {
+        return new Expressions.Quotient<Number>(x,y);
+    }
+
+    public Expression<Number> quot(Expression<? extends Number> x, Number y) {
+        return new Expressions.Quotient<Number>(x,y);
+    }
+
+    public Expression<Number> quot(Number x, Expression<? extends Number> y) {
+        return new Expressions.Quotient<Number>(x,y);
+    }
+
+    public <Y> Selection<Y> select(Class<Y> result, 
+        Selection<?>... selections) {
+        throw new AbstractMethodError();
+    }
+
+    public <R> Case<R> selectCase() {
+        throw new AbstractMethodError();
+
+    }
+
+    public <C, R> SimpleCase<C, R> selectCase(
+        Expression<? extends C> expression) {
+        throw new AbstractMethodError();
+    }
+
+    public <C extends Collection<?>> Expression<Integer> size(C collection) {
+        return new Expressions.Size(collection);
+    }
+
+    public <C extends Collection<?>> Expression<Integer> size(
+        Expression<C> collection) {
+        return new Expressions.Size(collection);
+    }
+
+    public <Y> Expression<Y> some(Subquery<Y> subquery) {
+        throw new AbstractMethodError();
+    }
+
+    public Expression<Double> sqrt(Expression<? extends Number> x) {
+        return new Expressions.Sqrt(x);
+    }
+
+    public Expression<String> substring(Expression<String> x,
+        Expression<Integer> from) {
+    	return new Expressions.Substring(x);
+    }
+
+    public Expression<String> substring(Expression<String> x, int from) {
+        return new Expressions.Substring(x, from);
+    }
+
+    public Expression<String> substring(Expression<String> x,
+        Expression<Integer> from, Expression<Integer> len) {
+        return new Expressions.Substring(x, from, len);
+    }
+
+    public Expression<String> substring(Expression<String> x, int from, 
+        int len) {
+        return new Expressions.Substring(x, from, len);
+    }
+
+    public <N extends Number> Expression<N> sum(Expression<N> x) {
+        return new Expressions.Sum<N>(x);
+    }
+
+    public <N extends Number> Expression<N> sum(Expression<? extends N> x,
+        Expression<? extends N> y) {
+        return new Expressions.Sum<N>(x,y);
+    }
+
+    public <N extends Number> Expression<N> sum(Expression<? extends N> x, 
+        N y) {
+        return new Expressions.Sum<N>(x,y);
+    }
+
+    public <N extends Number> Expression<N> sum(N x, 
+        Expression<? extends N> y) {
+        return new Expressions.Sum<N>(x,y);
+    }
+
+    public Expression<BigDecimal> toBigDecimal(
+        Expression<? extends Number> number) {
+        return new Expressions.Cast<BigDecimal>(number, BigDecimal.class);
+    }
+
+    public Expression<BigInteger> toBigInteger(
+        Expression<? extends Number> number) {
+        return new Expressions.Cast<BigInteger>(number, BigInteger.class);
+    }
+
+    public Expression<Double> toDouble(Expression<? extends Number> number) {
+        return new Expressions.Cast<Double>(number, Double.class);
+    }
+
+    public Expression<Float> toFloat(Expression<? extends Number> number) {
+        return new Expressions.Cast<Float>(number, Float.class);
+    }
+
+    public Expression<Integer> toInteger(Expression<? extends Number> number) {
+        return new Expressions.Cast<Integer>(number, Integer.class);
+    }
+
+    public Expression<Long> toLong(Expression<? extends Number> number) {
+        return new Expressions.Cast<Long>(number, Long.class);
+    }
+
+    public Expression<String> toString(Expression<Character> character) {
+        return new Expressions.Cast<String>(character, String.class);
+    }
+
+    public Expression<String> trim(Expression<String> x) {
+        return new Expressions.Trim(x);
+    }
+
+    public Expression<String> trim(Trimspec ts, Expression<String> x) {
+        return new Expressions.Trim(x, ts);
+    }
+
+    public Expression<String> trim(Expression<Character> t, 
+        Expression<String> x) {
+        return new Expressions.Trim(x, t);
+    }
+
+    public Expression<String> trim(char t, Expression<String> x) {
+        return new Expressions.Trim(x, t);
+    }
+
+    public Expression<String> trim(Trimspec ts, Expression<Character> t,
+        Expression<String> x) {
+        return new Expressions.Trim(x, t, ts);
+    }
+
+    public Expression<String> trim(Trimspec ts, char t, Expression<String> x) {
+        return new Expressions.Trim(x, t, ts);
+    }
+
+    public Expression<String> upper(Expression<String> x) {
+        throw new AbstractMethodError();
+
+    }
+
+    public <V, M extends Map<?, V>> Expression<Collection<V>> values(M map) {
+        throw new AbstractMethodError();
+    }
+}
diff --git a/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/CriteriaQueryImpl.java b/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/CriteriaQueryImpl.java
new file mode 100644
index 000000000..764a3d784
--- /dev/null
+++ b/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/CriteriaQueryImpl.java
@@ -0,0 +1,218 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.    
+ */
+package org.apache.openjpa.persistence.criteria;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.LinkedHashSet;
+import java.util.List;
+import java.util.Set;
+
+import javax.persistence.Parameter;
+import javax.persistence.criteria.CriteriaQuery;
+import javax.persistence.criteria.Expression;
+import javax.persistence.criteria.Order;
+import javax.persistence.criteria.Predicate;
+import javax.persistence.criteria.Root;
+import javax.persistence.criteria.Selection;
+import javax.persistence.criteria.Subquery;
+import javax.persistence.metamodel.Entity;
+
+import org.apache.openjpa.kernel.exps.ExpressionFactory;
+import org.apache.openjpa.kernel.exps.QueryExpressions;
+import org.apache.openjpa.kernel.exps.Value;
+import org.apache.openjpa.meta.ClassMetaData;
+import org.apache.openjpa.persistence.meta.MetamodelImpl;
+import org.apache.openjpa.persistence.meta.Types;
+
+/**
+ * Criteria query implementation.
+ * 
+ * @author Pinaki Poddar
+ *
+ */
+public class CriteriaQueryImpl implements CriteriaQuery {
+    private final MetamodelImpl  _model;
+    private Set<Root<?>>        _roots;
+    private PredicateImpl       _where;
+    private List<Order>         _orders;
+    private Set<Parameter<?>>   _params;
+    private List<Selection<?>>  _selections;
+    private List<Expression<?>> _groups;
+    private PredicateImpl       _having;
+    private Boolean             _distinct;
+    
+    public CriteriaQueryImpl(MetamodelImpl model) {
+        this._model = model;
+    }
+
+    public CriteriaQuery distinct(boolean distinct) {
+        _distinct = distinct;
+        return this;
+    }
+
+    public List<Order> getOrderList() {
+        return _orders;
+    }
+
+    public Set<Parameter<?>> getParameters() {
+        return _params;
+    }
+
+    public List<Selection<?>> getSelectionList() {
+        return _selections;
+    }
+
+    public CriteriaQuery groupBy(Expression<?>... grouping) {
+    	_groups = new ArrayList<Expression<?>>();
+    	for (Expression<?> e : grouping)
+    		_groups.add(e);
+        return this;
+    }
+
+    public CriteriaQuery having(Expression<Boolean> restriction) {
+        _having = new PredicateImpl().add(restriction);
+        return this;
+    }
+
+    public CriteriaQuery having(Predicate... restrictions) {
+        _having = new PredicateImpl();
+        for (Predicate p : restrictions)
+        	_having.add(p);
+        return this;
+    }
+
+    public CriteriaQuery orderBy(Order... o) {
+        _orders = Arrays.asList(o);
+        return this;
+    }
+
+    public CriteriaQuery select(Selection<?>... selections) {
+        _selections = Arrays.asList(selections);
+        return this;
+    }
+
+    public CriteriaQuery where(Expression<Boolean> restriction) {
+        _where = new PredicateImpl().add(restriction);
+        return this;
+    }
+
+    public CriteriaQuery where(Predicate... restrictions) {
+        _where = new PredicateImpl();
+        for (Predicate p : restrictions)
+        	_where.add(p);
+        return this;
+    }
+
+    public <X> Root<X> from(Entity<X> entity) {
+        Root<X> root = new RootImpl<X>(entity);
+        if (_roots == null) {
+            _roots = new LinkedHashSet<Root<?>>();
+        }
+        _roots.add(root);
+        return root;
+    }
+
+    public <X> Root<X> from(Class<X> entityClass) {
+        return from(_model.entity(entityClass));
+    }
+
+    public List<Expression<?>> getGroupList() {
+        return _groups;
+    }
+
+    public Predicate getGroupRestriction() {
+        return _having;
+    }
+
+    public PredicateImpl getRestriction() {
+        return _where;
+    }
+
+    public Set<Root<?>> getRoots() {
+        return _roots;
+    }
+    
+    public Root<?> getRoot() {
+        if (_roots == null || _roots.isEmpty())
+            throw new IllegalStateException("no root is set");
+        return _roots.iterator().next();
+    }
+
+    public boolean isDistinct() {
+        return _distinct;
+    }
+
+    public <U> Subquery<U> subquery(Class<U> type) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+    
+    /**
+     * Populate kernel expressions.
+     */
+    QueryExpressions getQueryExpressions(ExpressionFactory factory) {
+	    QueryExpressions exps = new QueryExpressions();
+	    
+	    if (_roots != null) {
+	    	exps.accessPath = new ClassMetaData[_roots.size()];
+	    	int i = 0;
+	    	for (Root<?> r : _roots)
+	    	   exps.accessPath[i++] = ((Types.Managed<?>)r.getModel()).meta;
+	    }
+	//    exps.alias = null;      // String   
+	    exps.ascending = new boolean[]{false};
+	    exps.distinct = _distinct == null ? QueryExpressions.DISTINCT_AUTO :
+	    	_distinct ? QueryExpressions.DISTINCT_TRUE 
+	    			  : QueryExpressions.DISTINCT_FALSE;
+	//    exps.fetchInnerPaths = null; // String[]
+	//    exps.fetchPaths = null;      // String[]
+	    exps.filter = _where == null ? factory.emptyExpression() 
+	    		: _where.toKernelExpression(factory, _model);
+	    
+	//    exps.grouping = null; // Value[]
+	//    exps.groupingClauses = null; // String[]
+	    exps.having = _having == null ? factory.emptyExpression() 
+	    		: _having.toKernelExpression(factory, _model);
+	//    exps.operation = QueryOperations.OP_SELECT;
+	//    exps.ordering = null; //Value[]
+	//    exps.orderingAliases = null; // String[]
+	//    exps.orderingClauses = null; // String[]
+	//    exps.parameterTypes = null; // LinkedMap<>
+	//    exps.projectionAliases = null; // String[]
+	//    exps.projectionClauses = null; // String[]
+	      exps.projections = toValues(factory, getSelectionList());
+	//    exps.range = null; // Value[]
+	//    exps.resultClass = null; // Class
+	    return exps;
+    }
+
+
+    Value[] toValues(ExpressionFactory factory, List<Selection<?>> sels) {
+    	if (sels == null || (sels.size() == 1 && sels.get(0) == getRoot()))
+    			return new Value[0];
+    	Value[] result = new Value[sels.size()];
+    	int i = 0;
+    	for (Selection<?> s : sels) {
+    		result[i++] = ((ExpressionImpl<?>)s).toValue(factory, _model);
+    	}
+    	return result;
+    }
+
+}
diff --git a/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/ExpressionImpl.java b/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/ExpressionImpl.java
new file mode 100644
index 000000000..731ed9c1f
--- /dev/null
+++ b/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/ExpressionImpl.java
@@ -0,0 +1,91 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.openjpa.persistence.criteria;
+
+import java.util.Collection;
+
+import javax.persistence.criteria.Expression;
+import javax.persistence.criteria.Predicate;
+
+import org.apache.openjpa.kernel.exps.ExpressionFactory;
+import org.apache.openjpa.kernel.exps.Value;
+import org.apache.openjpa.persistence.meta.MetamodelImpl;
+
+/**
+ * Expression for Criteria query.
+ * 
+ * @author Pinaki Poddar
+ *
+ * @param <X> the type of the value this expression represents.
+ */
+public abstract class ExpressionImpl<X> extends SelectionImpl<X> 
+    implements Expression<X> {
+
+    Value toValue(ExpressionFactory factory, MetamodelImpl model) {
+        throw new AbstractMethodError(this.getClass().getName());
+    }
+    
+    org.apache.openjpa.kernel.exps.Expression toKernelExpression(
+        ExpressionFactory factory, MetamodelImpl model) {
+        throw new AbstractMethodError(this.getClass().getName());
+    }
+    
+    /**
+     * @param cls the type of the evaluated result of the expression
+     */
+    public ExpressionImpl(Class<X> cls) {
+        super(cls);
+    }
+
+    public <Y> Expression<Y> as(Class<Y> type) {
+        // TODO Auto-generated method stub
+        throw new AbstractMethodError();
+    }
+
+    public Predicate in(Object... values) {
+        // TODO Auto-generated method stub
+        throw new AbstractMethodError();
+    }
+
+    public Predicate in(Expression<?>... values) {
+        // TODO Auto-generated method stub
+        throw new AbstractMethodError();
+    }
+
+    public Predicate in(Collection<?> values) {
+        // TODO Auto-generated method stub
+        throw new AbstractMethodError();
+    }
+
+    public Predicate in(Expression<?> values) {
+        // TODO Auto-generated method stub
+        throw new AbstractMethodError();
+    }
+
+    public Predicate isNotNull() {
+        // TODO Auto-generated method stub
+        throw new AbstractMethodError();
+    }
+
+    public Predicate isNull() {
+        // TODO Auto-generated method stub
+        throw new AbstractMethodError();
+    }
+}
diff --git a/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/Expressions.java b/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/Expressions.java
new file mode 100644
index 000000000..43ea0a5f3
--- /dev/null
+++ b/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/Expressions.java
@@ -0,0 +1,724 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.openjpa.persistence.criteria;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+
+import javax.persistence.criteria.Expression;
+import javax.persistence.criteria.QueryBuilder;
+import javax.persistence.criteria.QueryBuilder.Trimspec;
+
+import org.apache.openjpa.kernel.exps.ExpressionFactory;
+import org.apache.openjpa.kernel.exps.Value;
+import org.apache.openjpa.kernel.jpql.JPQLExpressionBuilder;
+import org.apache.openjpa.persistence.meta.MetamodelImpl;
+
+public class Expressions {
+	
+	static Value toValue(ExpressionImpl<?> e, ExpressionFactory factory, 
+		MetamodelImpl model) {
+		Value v = e.toValue(factory, model);
+		v.setImplicitType(e.getJavaType());
+		v.setAlias(e.getAlias());
+		return v;
+	}
+	
+	/**
+	 * Unary Functional Expression applies a unary function on a input
+	 * Expression.
+	 *
+	 * @param <X> the type of the resultant expression
+	 */
+    public static class UnaryFunctionalExpression<X> 
+        extends ExpressionImpl<X> {
+        protected ExpressionImpl<?> e;
+        
+        public UnaryFunctionalExpression(Class<X> t, Expression<?> e) {
+            super(t);
+            this.e  = (ExpressionImpl<?>)e;
+        }
+        
+        public UnaryFunctionalExpression(Expression<X> e) {
+            this(e.getJavaType(), e);
+        }
+    }
+    
+    /**
+     * Binary Functional Expression applies a binary function on a pair of
+     * input Expression.
+     * 
+     *
+	 * @param <X> the type of the resultant expression
+     */
+    public static class BinarayFunctionalExpression<X> 
+        extends ExpressionImpl<X>{
+        protected ExpressionImpl<?> e1;
+        protected ExpressionImpl<?> e2;
+        
+        public BinarayFunctionalExpression(Class<X> t, Expression<?> x, 
+        		Expression<?> y) {
+            super(t);
+            e1 = (ExpressionImpl<?>)x;
+            e2 = (ExpressionImpl<?>)y;
+        }
+    }
+
+    
+    /**
+     * Binary Logical Expression applies a binary function on a pair of
+     * input Expression to generate a Predicate.
+     *
+     */
+   public static class BinaryLogicalExpression extends PredicateImpl{
+        protected ExpressionImpl<?> e1;
+        protected ExpressionImpl<?> e2;
+        
+        public BinaryLogicalExpression(Expression<?> x, Expression<?> y) {
+            super();
+            e1 = (ExpressionImpl<?>)x;
+            e2 = (ExpressionImpl<?>)y;
+        }
+    }
+    
+    
+    public static class Abs<X> extends UnaryFunctionalExpression<X> {
+    	public  Abs(Expression<X> x) {
+    		super(x);
+    	}
+
+    	@Override
+        public Value toValue(ExpressionFactory factory, MetamodelImpl model) {
+            return factory.abs(Expressions.toValue(e, factory, model));
+        }
+    }
+    
+    public static class Count extends UnaryFunctionalExpression<Long> {
+    	private boolean _distinct; 
+    	public  Count(Expression<?> x) {
+    		this(x, false);
+    	}
+    	
+    	public  Count(Expression<?> x, boolean distinct) {
+    		super(Long.class, x);
+    		_distinct = distinct;
+    		
+    	}
+
+    	@Override
+        public Value toValue(ExpressionFactory factory, MetamodelImpl model) {
+            Value v = factory.count(Expressions.toValue(e, factory, model));
+            return _distinct ? factory.distinct(v) : v;
+        }
+    }
+
+    public static class Avg extends UnaryFunctionalExpression<Double> {
+    	public  Avg(Expression<?> x) {
+    		super(Double.class, x);
+    	}
+
+    	@Override
+        public Value toValue(ExpressionFactory factory, MetamodelImpl model) {
+            return factory.avg(Expressions.toValue(e, factory, model));
+        }
+    }
+    
+    public static class Sqrt extends UnaryFunctionalExpression<Double> {
+    	public  Sqrt(Expression<? extends Number> x) {
+    		super(Double.class, x);
+    	}
+
+    	@Override
+        public Value toValue(ExpressionFactory factory, MetamodelImpl model) {
+            return factory.sqrt(Expressions.toValue(e, factory, model));
+        }
+    }
+    
+    public static class Max<X> extends UnaryFunctionalExpression<X> {
+    	public  Max(Expression<X> x) {
+    		super(x);
+    	}
+
+    	@Override
+        public Value toValue(ExpressionFactory factory, MetamodelImpl model) {
+            return factory.max(Expressions.toValue(e, factory, model));
+        }
+    }
+
+    public static class Min<X> extends UnaryFunctionalExpression<X> {
+    	public  Min(Expression<X> x) {
+    		super(x);
+    	}
+
+    	@Override
+        public Value toValue(ExpressionFactory factory, MetamodelImpl model) {
+            return factory.min(Expressions.toValue(e, factory, model));
+        }
+    }
+    
+    public static class Size extends UnaryFunctionalExpression<Integer> {
+    	public  Size(Expression<? extends Collection<?>> x) {
+    		super(Integer.class, x);
+    	}
+    	
+    	public  Size(Collection<?> x) {
+    		this(new Constant<Collection<?>>(x));
+    	}
+
+    	@Override
+        public Value toValue(ExpressionFactory factory, MetamodelImpl model) {
+            return factory.size(Expressions.toValue(e, factory, model));
+        }
+    }
+
+    public static class Cast<B> extends UnaryFunctionalExpression<B> {
+    	Class<B> b;
+    	public Cast(Expression<?> x, Class<B> b) {
+    		super(b, x);
+    	}
+
+    	@Override
+        public Value toValue(ExpressionFactory factory, MetamodelImpl model) {
+            return factory.cast(Expressions.toValue(e, factory, model), b);
+        }
+    }
+    public static class Concat extends BinarayFunctionalExpression<String> {
+    	public Concat(Expression<String> x, Expression<String> y) {
+    		super(String.class, x, y);
+    	}
+    	
+    	public Concat(Expression<String> x, String y) {
+    		this(x, new Constant<String>(y));
+    	}
+    	
+    	public Concat(String x, Expression<String> y) {
+    		this(new Constant<String>(x), y);
+    	}
+    	
+    	@Override
+        public Value toValue(ExpressionFactory factory, MetamodelImpl model) {
+            return factory.concat(
+            	Expressions.toValue(e1, factory, model), 
+            	Expressions.toValue(e2, factory, model));
+        }
+    }
+    
+    public static class Substring extends UnaryFunctionalExpression<String> {
+    	private ExpressionImpl<Integer> from;
+    	private ExpressionImpl<Integer> len;
+    	
+    	public Substring(Expression<String> s, Expression<Integer> from, 
+    			Expression<Integer> len) {
+    		super(s);
+    		this.from = (ExpressionImpl<Integer>)from;
+    		this.len  = (ExpressionImpl<Integer>)len;
+    	}
+    	
+    	public Substring(Expression<String> s) {
+    		this(s, (Expression<Integer>)null, (Expression<Integer>)null);
+    	}
+    	
+    	public Substring(Expression<String> s, Integer from) {
+    		this(s, new Constant<Integer>(from), null);
+    	}
+    	
+    	public Substring(Expression<String> s, Integer from, Integer len) {
+            this(s, new Constant<Integer>(from), new Constant<Integer>(len));
+    	}
+    	
+    	@Override
+        public Value toValue(ExpressionFactory factory, MetamodelImpl model) {
+            return JPQLExpressionBuilder.convertSubstringArguments(factory, 
+            	Expressions.toValue(e, factory, model), 
+            	from == null ? null : from.toValue(factory, model), 
+            	len == null ? null : len.toValue(factory, model));
+        }
+    }
+    
+    public static class Trim extends BinarayFunctionalExpression<String> {
+    	static Expression<Character> defaultTrim = new Constant<Character>
+    	   (Character.class, new Character(' '));
+    	static Trimspec defaultSpec = Trimspec.BOTH;
+    	Trimspec ts;
+    	public Trim(Expression<String> x, Expression<Character> y, 
+    		Trimspec ts) {
+    		super(String.class, x, y);
+    		this.ts = ts;
+    	}
+    	
+    	public Trim(Expression<String> x, Expression<Character> y) {
+    		this(x, y, defaultSpec);
+    	}
+    	
+    	public Trim(Expression<String> x) {
+    		this(x, defaultTrim, defaultSpec);
+    	}
+    	
+    	public Trim(Expression<String> x, Character t) {
+            this(x, new Constant<Character>(Character.class, t), defaultSpec);
+    	}
+    	
+    	public Trim(Expression<String> x, Character t, Trimspec ts) {
+    		this(x, new Constant<Character>(Character.class, t), ts);
+    	}
+    	
+    	public Trim(Expression<String> x, Trimspec ts) {
+    		this(x, defaultTrim, ts);
+    	}
+
+    	@Override
+        public Value toValue(ExpressionFactory factory, MetamodelImpl model) {
+    		Boolean spec = null;
+    		if (ts != null) {
+    			switch (ts) {
+    			case LEADING : spec = true; break;
+    			case TRAILING : spec = false; break;
+    			case BOTH : spec = null; break;
+    			}
+    		}
+            return factory.trim(
+            	Expressions.toValue(e1, factory, model), 
+            	Expressions.toValue(e2, factory, model), spec);
+        }
+    }
+
+
+    
+    public static class Sum<N extends Number> 
+        extends BinarayFunctionalExpression<N> {
+    	public Sum(Expression<? extends Number> x, 
+    		Expression<? extends Number> y) {
+    		super((Class<N>)x.getJavaType(), x, y);
+    	}
+    	
+    	public Sum(Expression<? extends Number> x) {
+    		this(x, (Expression<? extends Number>)null);
+    	}
+    	
+
+    	public Sum(Expression<? extends Number> x, Number y) {
+    		this(x, new Constant<Number>(Number.class, y));
+    	}
+
+    	public Sum(Number x, Expression<? extends Number> y) {
+    		this(new Constant<Number>(Number.class, x), y);
+    	}
+    	
+    	@Override
+        public Value toValue(ExpressionFactory factory, MetamodelImpl model) {
+    		return (e2 == null) 
+            ?   factory.sum(Expressions.toValue(e1, factory, model))
+    		:   factory.add(
+    			   Expressions.toValue(e1, factory, model), 
+    			   Expressions.toValue(e2, factory, model));
+        }
+    }
+    
+    public static class Product<N extends Number> 
+        extends BinarayFunctionalExpression<N> {
+    	public Product(Expression<? extends Number> x, 
+    		Expression<? extends Number> y) {
+    		super((Class<N>)x.getJavaType(), x, y);
+    	}
+
+    	public Product(Expression<? extends Number> x, Number y) {
+    		this(x, new Constant<Number>(Number.class, y));
+    	}
+
+    	public Product(Number x, Expression<? extends Number> y) {
+    		this(new Constant<Number>(Number.class, x), y);
+    	}
+    	
+    	@Override
+        public Value toValue(ExpressionFactory factory, MetamodelImpl model) {
+            return factory.multiply(
+            	Expressions.toValue(e1, factory, model), 
+            	Expressions.toValue(e2, factory, model));
+        }
+    }
+    
+    public static class Diff<N extends Number> 
+        extends BinarayFunctionalExpression<N> {
+    	public Diff(Expression<? extends Number> x, 
+    		Expression<? extends Number> y) {
+    		super((Class<N>)x.getJavaType(), x, y);
+    	}
+
+    	public Diff(Expression<? extends Number> x, Number y) {
+    		this(x, new Constant<Number>(Number.class, y));
+    	}
+
+    	public Diff(Number x, Expression<? extends Number> y) {
+    		this(new Constant<Number>(Number.class, x), y);
+    	}
+    	
+    	@Override
+        public Value toValue(ExpressionFactory factory, MetamodelImpl model) {
+            return factory.subtract(
+            	Expressions.toValue(e1, factory, model), 
+            	Expressions.toValue(e2, factory, model));
+        }
+    }
+
+    
+    public static class Quotient<N extends Number> 
+        extends BinarayFunctionalExpression<N> {
+    	public Quotient(Expression<? extends Number> x, 
+    		Expression<? extends Number> y) {
+    		super((Class<N>)x.getJavaType(), x, y);
+    	}
+
+    	public Quotient(Expression<? extends Number> x, Number y) {
+    		this(x, new Constant<Number>(y));
+    	}
+
+    	public Quotient(Number x, Expression<? extends Number> y) {
+    		this(new Constant<Number>(x), y);
+    	}
+    	
+    	@Override
+        public Value toValue(ExpressionFactory factory, MetamodelImpl model) {
+            return factory.divide(
+            	Expressions.toValue(e1, factory, model), 
+            	Expressions.toValue(e2, factory, model));
+        }
+    }
+
+
+
+    public static class Mod extends BinarayFunctionalExpression<Integer> {
+    	public  Mod(Expression<Integer> x, Expression<Integer> y) {
+    		super(Integer.class, x,y);
+    	}
+    	public  Mod(Expression<Integer> x, Integer y) {
+    		this(x,new Constant<Integer>(Integer.class, y));
+    	}
+    	public  Mod(Integer x, Expression<Integer> y) {
+    		this(new Constant<Integer>(Integer.class, x),y);
+    	}
+
+    	@Override
+        public Value toValue(ExpressionFactory factory, MetamodelImpl model) {
+            return factory.mod(
+            	Expressions.toValue(e1, factory, model), 
+            	Expressions.toValue(e2, factory, model));
+        }
+    }
+
+    public static class CurrentDate extends ExpressionImpl<java.sql.Date> {
+    	public  CurrentDate() {
+    		super(java.sql.Date.class);
+    	}
+
+    	@Override
+        public Value toValue(ExpressionFactory factory, MetamodelImpl model) {
+            return factory.getCurrentDate();
+        }
+    }
+    
+    public static class CurrentTime extends ExpressionImpl<java.sql.Time> {
+    	public  CurrentTime() {
+    		super(java.sql.Time.class);
+    	}
+
+    	@Override
+        public Value toValue(ExpressionFactory factory, MetamodelImpl model) {
+            return factory.getCurrentTime();
+        }
+    }
+    
+    public static class CurrentTimestamp 
+        extends ExpressionImpl<java.sql.Timestamp> {
+    	public  CurrentTimestamp() {
+    		super(java.sql.Timestamp.class);
+    	}
+
+    	@Override
+        public Value toValue(ExpressionFactory factory, MetamodelImpl model) {
+            return factory.getCurrentTimestamp();
+        }
+    }
+
+    public static class Equal extends BinaryLogicalExpression {
+        public <X,Y> Equal(Expression<X> x, Expression<Y> y) {
+            super(x,y);
+        }
+        
+        public <X> Equal(Expression<X> x, Object y) {
+            this(x, new Constant<Object>(Object.class, y));
+        }
+        
+        @Override
+        org.apache.openjpa.kernel.exps.Expression toKernelExpression(
+            ExpressionFactory factory, MetamodelImpl model) {
+                return factory.equal(
+                	Expressions.toValue(e1, factory, model), 
+                	Expressions.toValue(e2, factory, model));
+        }
+    }
+    
+    public static class GreaterThan extends BinaryLogicalExpression {
+        public <X,Y> GreaterThan(Expression<X> x, Expression<Y> y) {
+            super(x,y);
+        }
+        
+        public <X> GreaterThan(Expression<X> x, Object y) {
+            this(x, new Constant<Object>(Object.class, y));
+        }
+        
+        @Override
+        org.apache.openjpa.kernel.exps.Expression toKernelExpression(
+            ExpressionFactory factory, MetamodelImpl model) {
+                return factory.greaterThan(
+                	Expressions.toValue(e1, factory, model), 
+                	Expressions.toValue(e2, factory, model));
+        }
+    }
+    
+    public static class GreaterThanEqual extends BinaryLogicalExpression {
+        public <X,Y> GreaterThanEqual(Expression<X> x, Expression<Y> y) {
+            super(x,y);
+        }
+        
+        public <X> GreaterThanEqual(Expression<X> x, Object y) {
+            this(x, new Constant<Object>(Object.class, y));
+        }
+        
+        @Override
+        org.apache.openjpa.kernel.exps.Expression toKernelExpression(
+            ExpressionFactory factory, MetamodelImpl model) {
+                return factory.greaterThanEqual(
+                    Expressions.toValue(e1, factory, model), 
+                    Expressions.toValue(e2, factory, model));
+        }
+    }
+
+   
+    public static class LessThan extends BinaryLogicalExpression {
+        public <X,Y> LessThan(Expression<X> x, Expression<Y> y) {
+            super(x,y);
+        }
+        
+        public <X> LessThan(Expression<X> x, Object y) {
+            this(x, new Constant<Object>(Object.class, y));
+        }
+        
+        @Override
+        org.apache.openjpa.kernel.exps.Expression toKernelExpression(
+            ExpressionFactory factory, MetamodelImpl model) {
+                return factory.lessThan(
+                    Expressions.toValue(e1, factory, model), 
+                    Expressions.toValue(e2, factory, model));
+        }
+    }
+    
+    public static class LessThanEqual extends BinaryLogicalExpression {
+        public <X,Y> LessThanEqual(Expression<X> x, Expression<Y> y) {
+            super(x,y);
+        }
+        
+        public <X> LessThanEqual(Expression<X> x, Object y) {
+            this(x, new Constant<Object>(Object.class, y));
+        }
+        
+        @Override
+        org.apache.openjpa.kernel.exps.Expression toKernelExpression(
+            ExpressionFactory factory, MetamodelImpl model) {
+                return factory.lessThanEqual(
+                	Expressions.toValue(e1, factory, model), 
+                    Expressions.toValue(e2, factory, model));
+
+        }
+    }
+
+    public static class Between<Y extends Comparable<Y>> 
+        extends PredicateImpl.And {
+        public Between(Expression<? extends Y> v, Expression<? extends Y> x,
+                Expression<? extends Y> y) {
+            super(new GreaterThanEqual(v,x), new LessThanEqual(v,y));
+        }
+        
+        public Between(Expression<? extends Y> v, Y x,
+                Y y) {
+            this(v, new Constant<Y>(x), new Constant<Y>(y));
+        }
+    }
+    
+    public static class Constant<X> extends ExpressionImpl<X> {
+        public final Object arg;
+        public Constant(Class<X> t, X x) {
+            super(t);
+            this.arg = x;
+        }
+        
+        public Constant(X x) {
+        	this((Class<X>)x.getClass(),x);
+        }
+        
+        @Override
+        public Value toValue(ExpressionFactory factory, MetamodelImpl model) {
+            return factory.newLiteral(arg, 1);
+        }
+        
+    }
+    
+    public static class IsEmpty extends PredicateImpl {
+    	ExpressionImpl<?> collection;
+    	public IsEmpty(Expression<?> collection) {
+    		super();
+    		this.collection = (ExpressionImpl<?>)collection;
+    	}
+    	
+        @Override
+        public org.apache.openjpa.kernel.exps.Expression toKernelExpression(
+        	ExpressionFactory factory, MetamodelImpl model) {
+            return factory.isEmpty(
+            	Expressions.toValue(collection, factory, model));
+        }
+    }
+    
+    public static class IsMember<E> extends PredicateImpl {
+    	ExpressionImpl<E> element;
+    	ExpressionImpl<?> collection;
+    	
+    	public IsMember(Class<E> t, Expression<E> element, 
+    		Expression<?> collection) {
+    		this.element = (ExpressionImpl<E>)element;
+    		this.collection = (ExpressionImpl<?>)collection;
+    	}
+    	
+    	public IsMember(Class<E> t, E element, Expression<?> collection) {
+    		this(t, new Constant<E>(element), collection);
+    	}
+    	
+    	public IsMember(E element, Expression<?> collection) {
+    		this((Class<E>)element.getClass(), element, collection);
+    	}
+    	
+        @Override
+        public org.apache.openjpa.kernel.exps.Expression toKernelExpression(
+        	ExpressionFactory factory, MetamodelImpl model) {
+            return factory.contains(factory.getThis(),
+            	Expressions.toValue(collection, factory, model));
+        }
+    }
+    
+    public static class Like extends PredicateImpl {
+    	ExpressionImpl<String> str;
+    	ExpressionImpl<String> pattern;
+    	ExpressionImpl<Character> escapeChar;
+    	static ExpressionImpl<Character> defaultEscape = 
+    		new Constant<Character>(new Character(' '));
+    	
+    	public Like(Expression<String> x, Expression<String> pattern,
+    	        Expression<Character> escapeChar) {
+    		super();
+    		this.str = (ExpressionImpl<String>)x;
+    		this.pattern = (ExpressionImpl<String>)pattern;
+    		this.escapeChar = (ExpressionImpl<Character>)escapeChar;
+    	}
+    	
+    	public Like(Expression<String> x, Expression<String> pat, char esc) {
+    		this(x, pat, new Constant<Character>(Character.class, esc));
+    	}
+    	
+    	public Like(Expression<String> x, Expression<String> pattern) {
+    		this(x, pattern, defaultEscape);
+    	}
+    	
+    	public Like(Expression<String> x, String pattern) {
+    		this(x, new Constant<String>(pattern), defaultEscape);
+    	}
+    	public Like(Expression<String> x, String pat,  
+    		Expression<Character> esc) {
+    		this(x, new Constant<String>(pat), esc);
+    	}
+    	public Like(Expression<String> x, String pat,  Character esc) {
+            this(x, new Constant<String>(pat), new Constant<Character>(esc));
+    	}
+
+    	@Override
+        public org.apache.openjpa.kernel.exps.Expression toKernelExpression(
+        	ExpressionFactory factory, MetamodelImpl model) {
+            return factory.matches(
+            	Expressions.toValue(str, factory, model), 
+            	Expressions.toValue(pattern, factory, model), "_", "%", 
+            	Expressions.toValue(escapeChar, factory, model).toString());
+        }
+    }
+    
+    public static class Coalesce<T> extends ExpressionImpl<T> 
+    	implements QueryBuilder.Coalesce<T> {
+    	private List<Expression<? extends T>> values = 
+    		new ArrayList<Expression<? extends T>>();
+    	
+    	public Coalesce() {
+    		super(null);
+    	}
+    	
+    	public Coalesce(Class<T> cls) {
+    		super(cls);
+    	}
+    	
+        public Coalesce<T> value(T value) {
+        	return value(new Constant<T>(value));
+        }
+        
+        public Coalesce<T> value(Expression<? extends T> value) {
+        	values.add(value); 
+        	return this;
+        }
+
+    	
+    	@Override
+        public org.apache.openjpa.kernel.exps.Value toValue(
+        	ExpressionFactory factory, MetamodelImpl model) {
+    		Value[] vs = new Value[values.size()];
+    		int i = 0;
+    		for (Expression<?> e : values)
+    	        vs[i++] = Expressions.toValue((ExpressionImpl<?>)e, 
+    	           factory, model);
+            return factory.coalesceExpression(vs);
+        }
+    }
+    
+    public static class In<T> extends PredicateImpl 
+    	implements QueryBuilder.In<T> {
+    	private List<Expression<? extends T>> values = 
+    		new ArrayList<Expression<? extends T>>();
+    	public In(Expression<?> e) {
+    		super(null);
+    	}
+    	
+    	public Expression<T> getExpression() {
+    		return null;
+    	}
+
+    	public In<T> value(T value) {
+        	return value(new Constant<T>(value));
+    	}
+
+    	public In<T> value(Expression<? extends T> value) {
+        	values.add(value); 
+        	return this;
+    	}
+    }
+}
diff --git a/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/FromImpl.java b/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/FromImpl.java
new file mode 100644
index 000000000..ba18cb2ec
--- /dev/null
+++ b/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/FromImpl.java
@@ -0,0 +1,248 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.openjpa.persistence.criteria;
+
+import javax.persistence.criteria.CollectionJoin;
+import javax.persistence.criteria.Fetch;
+import javax.persistence.criteria.From;
+import javax.persistence.criteria.Join;
+import javax.persistence.criteria.JoinType;
+import javax.persistence.criteria.ListJoin;
+import javax.persistence.criteria.MapJoin;
+import javax.persistence.criteria.SetJoin;
+import javax.persistence.metamodel.AbstractCollection;
+import javax.persistence.metamodel.Attribute;
+import javax.persistence.metamodel.Collection;
+import javax.persistence.metamodel.List;
+import javax.persistence.metamodel.ManagedType;
+import javax.persistence.metamodel.Map;
+import javax.persistence.metamodel.Set;
+
+import org.apache.openjpa.persistence.criteria.PathImpl;
+
+/**
+ * Represents a bound type, usually an entity that appears in the from clause, 
+ * but may also be an embeddable belonging to an entity in the from clause. 
+ * Serves as a factory for Joins of associations, embeddables and collections 
+ * belonging to the type, and for Paths of attributes belonging to the type.
+ * 
+ * @param <Z> the parent type of this receiver
+ * @param <X> the type represented by this receiver 
+ */
+
+public class FromImpl<Z,X> extends PathImpl<X> implements From<Z,X> {
+    private java.util.Set<Join<X, ?>> _joins;
+    private java.util.Set<Fetch<X, ?>> _fetches;
+    
+    /**
+     * Supply the non-null managed type.
+     */
+    public FromImpl(ManagedType<X> type) {
+        super(type.getJavaType());
+    }
+    
+    /**
+     *  Return the joins that have been made from this type.
+     *  @return joins made from this type
+     */
+    public java.util.Set<Join<X, ?>> getJoins() {
+        throw new AbstractMethodError();
+    }
+
+    /**
+     *  Join to the specified attribute using an inner join.
+     *  @param attribute  target of the join
+     *  @return the resulting join
+     */
+    public <Y> Join<X, Y> join(Attribute<? super X, Y> attribute) {
+        return join(attribute, JoinType.INNER);
+    }
+
+    /**
+     *  Join to the specified attribute using the given join type.
+     *  @param attribute  target of the join
+     *  @param jt  join type 
+     *  @return the resulting join
+     */
+    public <Y> Join<X, Y> join(Attribute<? super X, Y> attribute, JoinType jt) {
+        throw new AbstractMethodError();
+    }
+
+    /**
+     *  Join to the specified Collection-valued attribute using an 
+     *  inner join.
+     *  @param collection  target of the join
+     *  @return the resulting join
+     */
+    public <Y> CollectionJoin<X, Y> join(Collection<? super X, Y> collection) {
+        return join(collection, JoinType.INNER);
+    }
+
+    /**
+     *  Join to the specified Collection-valued attribute using the given 
+     *  join type.
+     *  @param collection  target of the join
+     *  @return the resulting join
+     */
+    public <Y> CollectionJoin<X, Y> join(Collection<? super X, Y> collection, 
+        JoinType jt) {
+        throw new AbstractMethodError();
+    }
+
+    /**
+     *  Join to the specified Set-valued attribute using an inner join.
+     *  @param set  target of the join
+     *  @return the resulting join
+     */
+    public <Y> SetJoin<X,Y> join(Set<? super X, Y> set) {
+        return join(set, JoinType.INNER);
+    }
+    
+    /**
+     *  Join to the specified Set-valued attribute using the given join type.
+     *  @param set  target of the join
+     *  @return the resulting join
+     */
+    public <Y> SetJoin<X,Y> join(Set<? super X, Y> set, JoinType jt) {
+        throw new AbstractMethodError();
+    }
+
+    /**
+     *  Join to the specified List-valued attribute using an inner join.
+     *  @param set  target of the join
+     *  @return the resulting join
+     */
+    public <Y> ListJoin<X,Y> join(List<? super X, Y> list) {
+        return join(list, JoinType.INNER);
+    }
+
+    /**
+     *  Join to the specified List-valued attribute using the given join type.
+     *  @param set  target of the join
+     *  @return the resulting join
+     */
+    public <Y> ListJoin<X,Y> join(List<? super X, Y> list, JoinType jt) {
+        throw new AbstractMethodError();
+    }
+    
+    /**
+     *  Join to the specified Map-valued attribute using an inner join.
+     *  @param set  target of the join
+     *  @return the resulting join
+     */
+    public <K,V> MapJoin<X,K,V> join(Map<? super X,K,V> map) {
+        return join(map, JoinType.INNER);
+    }
+
+    /**
+     *  Join to the specified Map-valued attribute using the given join type.
+     *  @param set  target of the join
+     *  @return the resulting join
+     */
+    public <K,V> MapJoin<X,K,V> join(Map<? super X,K,V> map, JoinType jt) {
+        throw new AbstractMethodError();
+    }
+    
+    // String based counterparts
+
+    public Join join(String attributeName) {
+        throw new AbstractMethodError();
+    }
+
+    public Join join(String attributeName, JoinType jt) {
+        throw new AbstractMethodError();
+    }
+
+
+    public CollectionJoin joinCollection(String attributeName) {
+        throw new AbstractMethodError();
+    }
+
+    public CollectionJoin joinCollection(String attributeName, JoinType jt) {
+        // TODO Auto-generated method stub
+        throw new AbstractMethodError();
+    }
+
+    public ListJoin joinList(String attributeName) {
+        // TODO Auto-generated method stub
+        throw new AbstractMethodError();
+    }
+
+    public ListJoin joinList(String attributeName, JoinType jt) {
+        // TODO Auto-generated method stub
+        throw new AbstractMethodError();
+    }
+
+    public MapJoin joinMap(String attributeName) {
+        // TODO Auto-generated method stub
+        throw new AbstractMethodError();
+    }
+
+    public MapJoin joinMap(String attributeName, JoinType jt) {
+        // TODO Auto-generated method stub
+        throw new AbstractMethodError();
+    }
+
+    public SetJoin joinSet(String attributeName) {
+        // TODO Auto-generated method stub
+        throw new AbstractMethodError();
+    }
+
+    public SetJoin joinSet(String attributeName, JoinType jt) {
+        // TODO Auto-generated method stub
+        throw new AbstractMethodError();
+    }
+
+    public Fetch fetch(Attribute assoc) {
+        // TODO Auto-generated method stub
+        throw new AbstractMethodError();
+    }
+
+    public Fetch fetch(AbstractCollection assoc) {
+        // TODO Auto-generated method stub
+        throw new AbstractMethodError();
+    }
+
+    public Fetch fetch(String assocName) {
+        // TODO Auto-generated method stub
+        throw new AbstractMethodError();
+    }
+
+    public Fetch fetch(Attribute assoc, JoinType jt) {
+        // TODO Auto-generated method stub
+        throw new AbstractMethodError();
+    }
+
+    public Fetch fetch(AbstractCollection assoc, JoinType jt) {
+        // TODO Auto-generated method stub
+        throw new AbstractMethodError();
+    }
+
+    public Fetch fetch(String assocName, JoinType jt) {
+        // TODO Auto-generated method stub
+        throw new AbstractMethodError();
+    }
+
+    public java.util.Set<Fetch<X, ?>> getFetches() {
+        // TODO Auto-generated method stub
+        throw new AbstractMethodError();
+    }
+
+}
diff --git a/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/OrderImpl.java b/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/OrderImpl.java
new file mode 100644
index 000000000..dee96c895
--- /dev/null
+++ b/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/OrderImpl.java
@@ -0,0 +1,54 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.    
+ */
+package org.apache.openjpa.persistence.criteria;
+
+import javax.persistence.criteria.Expression;
+import javax.persistence.criteria.Order;
+
+/**
+ * Ordering clause of a criteria query.
+ * 
+ * @author Pinaki Poddar
+ *
+ */
+public class OrderImpl implements Order {
+	private boolean _ascending;
+	private final Expression<?> e;
+	
+	public OrderImpl(Expression<?> e, boolean asc) {
+		this.e = e;
+		_ascending = asc;
+	}
+	
+	public OrderImpl(Expression<?> e) {
+		this(e, true);
+	}
+	
+	public <T extends Comparable<T>> Expression<T> getExpression() {
+		return (Expression<T>)e;
+	}
+
+	public boolean isAscending() {
+		return _ascending;
+	}
+
+	public void reverse() {
+		_ascending = !_ascending;
+	}
+}
diff --git a/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/ParameterImpl.java b/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/ParameterImpl.java
new file mode 100644
index 000000000..4a81a875a
--- /dev/null
+++ b/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/ParameterImpl.java
@@ -0,0 +1,51 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.    
+ */
+package org.apache.openjpa.persistence.criteria;
+
+import javax.persistence.Parameter;
+
+/**
+ * Parameter of a criteria query.
+ * 
+ * @author Pinaki Poddar
+ *
+ * @param <T> the type of value held by this parameter.
+ */
+public class ParameterImpl<T> extends ExpressionImpl<T> implements Parameter<T>{
+	private String name;
+	private int position;
+	
+    public ParameterImpl(Class<T> cls) {
+        super(cls);
+    }
+
+	public final String getName() {
+		return name;
+	}
+	
+	public final ParameterImpl<T> setName(String name) {
+		this.name = name;
+		return this;
+	}
+
+	public final Integer getPosition() {
+		return position;
+	}
+
+}
diff --git a/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/PathImpl.java b/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/PathImpl.java
new file mode 100644
index 000000000..fa6fb309b
--- /dev/null
+++ b/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/PathImpl.java
@@ -0,0 +1,114 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.openjpa.persistence.criteria;
+
+import javax.persistence.criteria.Expression;
+import javax.persistence.criteria.Path;
+import javax.persistence.metamodel.AbstractCollection;
+import javax.persistence.metamodel.Attribute;
+import javax.persistence.metamodel.Bindable;
+import javax.persistence.metamodel.Map;
+
+import org.apache.openjpa.kernel.exps.ExpressionFactory;
+import org.apache.openjpa.kernel.exps.Value;
+import org.apache.openjpa.persistence.meta.Members;
+import org.apache.openjpa.persistence.meta.MetamodelImpl;
+
+/**
+ * Path from another (parent) path.
+ * 
+ * @author ppoddar
+ *
+ * @param <X>
+ */
+public class PathImpl<X> extends ExpressionImpl<X> implements Path<X> {
+    private PathImpl<?> _parent;
+    private Members.Member<?,X> member;
+    
+    /**
+     * 
+     * @param cls
+     */
+    protected PathImpl(Class<X> cls) {
+        super(cls);
+    }
+    
+    public <Z> PathImpl(Members.Member<Z, X> member) {
+        super(member.getMemberJavaType());
+        this.member = member;
+    }
+    
+    public <Z> PathImpl(PathImpl<Z> parent, 
+        Members.Member<? super Z, X> member) {
+        super(member.getMemberJavaType());
+        _parent = parent;
+        this.member = member;
+    }
+    
+    @Override
+    public Value toValue(ExpressionFactory factory, MetamodelImpl model) {
+        Value var = null;
+        if (_parent != null) { 
+            org.apache.openjpa.kernel.exps.Path path = 
+                (org.apache.openjpa.kernel.exps.Path)
+                _parent.toValue(factory, model);
+            path.get(member.fmd, false);
+            var = path;
+        } else {
+            var = factory.newPath();//getJavaType());
+            var.setMetaData(model.repos.getMetaData(getJavaType(), null, true));
+        }
+        return var;
+    }
+
+    public <Y> Path<Y> get(Attribute<? super X, Y> attr) {
+        return new PathImpl(this, (Members.Member<? super X, Y>)attr);
+    }
+
+    public Expression get(AbstractCollection collection) {
+        // TODO Auto-generated method stub
+        throw new AbstractMethodError();
+    }
+
+    public Expression get(Map collection) {
+        // TODO Auto-generated method stub
+        throw new AbstractMethodError();
+    }
+
+    public Path get(String attName) {
+        // TODO Auto-generated method stub
+        throw new AbstractMethodError();
+    }
+  //TODO: what does this return for a collection key, value? null?
+    public Bindable<X> getModel() { 
+        // TODO Auto-generated method stub
+        throw new AbstractMethodError();
+    }
+    
+    public Path<?> getParentPath() {
+        return _parent;
+    }
+
+    public Expression<Class<? extends X>> type() {
+        // TODO Auto-generated method stub
+        throw new AbstractMethodError();
+    }
+
+}
diff --git a/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/PredicateImpl.java b/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/PredicateImpl.java
new file mode 100644
index 000000000..e7a9b7a05
--- /dev/null
+++ b/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/PredicateImpl.java
@@ -0,0 +1,125 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.    
+ */
+package org.apache.openjpa.persistence.criteria;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import javax.persistence.criteria.Expression;
+import javax.persistence.criteria.Predicate;
+
+import org.apache.openjpa.kernel.exps.ExpressionFactory;
+import org.apache.openjpa.persistence.meta.MetamodelImpl;
+
+public class PredicateImpl extends ExpressionImpl<Boolean> 
+    implements Predicate {
+    List<Expression<Boolean>> _exps;
+    BooleanOperator _op;
+    boolean _negated = false;
+    
+    protected PredicateImpl() {
+    	super(Boolean.class);
+    }
+                               
+    protected PredicateImpl(BooleanOperator op) {
+        this();
+        _op = op;
+    }
+    
+    protected PredicateImpl(BooleanOperator op, Predicate...restrictions) {
+		this(op);
+		for (Predicate p : restrictions)
+			add((PredicateImpl)p);
+	}
+
+    public PredicateImpl add(Expression<Boolean> s) {
+        if (_exps == null)
+            _exps = new ArrayList<Expression<Boolean>>();
+        _exps.add(s);
+        return this;
+    }
+
+    public List<Expression<Boolean>> getExpressions() {
+        return _exps;
+    }
+
+    public BooleanOperator getOperator() {
+        return _op;
+    }
+
+    public boolean isNegated() {
+        return _negated;
+    }
+
+    public PredicateImpl negate() {
+        PredicateImpl not = new PredicateImpl(_op);
+        not._negated = true;
+        not._exps = new ArrayList<Expression<Boolean>>(this._exps);
+        not._op = this._op;
+        return not;
+    }
+    
+    @Override
+    org.apache.openjpa.kernel.exps.Expression toKernelExpression(
+        ExpressionFactory factory, MetamodelImpl model) {
+    		if (_exps == null || _exps.isEmpty())
+    			return factory.emptyExpression();
+    		if (_exps.size() == 1)
+    			return ((ExpressionImpl<?>)_exps.get(0))
+    			   .toKernelExpression(factory, model);
+    		ExpressionImpl<?> e1 = (ExpressionImpl<?>)_exps.get(0);
+    		ExpressionImpl<?> e2 = (ExpressionImpl<?>)_exps.get(1);
+    		org.apache.openjpa.kernel.exps.Expression ke1 = 
+    			e1.toKernelExpression(factory, model);
+    		org.apache.openjpa.kernel.exps.Expression ke2 = 
+    			e2.toKernelExpression(factory, model);
+    		org.apache.openjpa.kernel.exps.Expression result = 
+    			_op == BooleanOperator.AND ?
+    			factory.and(ke1,ke2) : factory.or(ke1, ke2);
+
+    		for (int i = 2; i < _exps.size(); i++) {
+    			ExpressionImpl<?> e = (ExpressionImpl<?>)_exps.get(i);
+    			result = factory.and(result, 
+    				e.toKernelExpression(factory, model));
+    		}
+    		return _negated ? factory.not(result) : result;
+    }
+        
+    public static class And extends PredicateImpl {
+    	public And(Expression<Boolean> x, Expression<Boolean> y) {
+    		super(BooleanOperator.AND);
+    		add(x).add(y);
+    	}
+    	
+    	public And(Predicate...restrictions) {
+    		super(BooleanOperator.AND, restrictions);
+    	}
+   }
+    
+    public static class Or extends PredicateImpl {
+    	public Or(Expression<Boolean> x, Expression<Boolean> y) {
+    		super(BooleanOperator.OR);
+    		add(x).add(y);
+    	}
+    	
+    	public Or(Predicate...restrictions) {
+    		super(BooleanOperator.AND, restrictions);
+    	}
+    }
+}
diff --git a/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/RootImpl.java b/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/RootImpl.java
new file mode 100644
index 000000000..23831f3ec
--- /dev/null
+++ b/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/RootImpl.java
@@ -0,0 +1,45 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.openjpa.persistence.criteria;
+
+import javax.persistence.criteria.Root;
+import javax.persistence.metamodel.Entity;
+
+import org.apache.openjpa.persistence.criteria.FromImpl;
+
+/**
+ * A path from itself.
+ * 
+ * @author Pinaki Poddar
+ *
+ * @param <X>
+ */
+public class RootImpl<X> extends FromImpl<X,X> implements Root<X> {
+	private final Entity<X> _entity;
+	
+    public RootImpl(Entity<X> type) {
+        super(type);
+        _entity = type;
+    }
+    
+    public  Entity<X> getModel() {
+        return _entity;
+    }
+}
diff --git a/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/SelectionImpl.java b/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/SelectionImpl.java
new file mode 100644
index 000000000..ee8fef5d5
--- /dev/null
+++ b/openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/SelectionImpl.java
@@ -0,0 +1,38 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.    
+ */
+package org.apache.openjpa.persistence.criteria;
+
+import javax.persistence.criteria.Selection;
+
+import org.apache.openjpa.persistence.ResultItemImpl;
+
+/**
+ * An item selected in the projection clause of  Criteria query.
+ * 
+ * @author Pinaki Poddar
+ *
+ * @param <X>
+ */
+public class SelectionImpl<X> extends ResultItemImpl<X> 
+    implements Selection<X> {
+
+    public SelectionImpl(Class<X> cls) {
+        super(cls);
+    }
+}
diff --git a/openjpa-persistence/src/main/resources/META-INF/services/org.apache.openjpa.kernel.exps.ExpressionParser b/openjpa-persistence/src/main/resources/META-INF/services/org.apache.openjpa.kernel.exps.ExpressionParser
new file mode 100644
index 000000000..2802f6bee
--- /dev/null
+++ b/openjpa-persistence/src/main/resources/META-INF/services/org.apache.openjpa.kernel.exps.ExpressionParser
@@ -0,0 +1,17 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+org.apache.openjpa.persistence.criteria.CriteriaBuilder