Initial import

apache-olingo/olingo2/src/main/java/org/baeldung/examples/olingo2/CarsODataJPAServiceFactory.java

@@ -19,10 +19,13 @@ import javax.persistence.criteria.CriteriaDelete;
 import javax.persistence.criteria.CriteriaQuery;
 import javax.persistence.criteria.CriteriaUpdate;
 import javax.persistence.metamodel.Metamodel;
+import javax.servlet.http.HttpServletRequest;
 
+import org.apache.olingo.odata2.api.processor.ODataContext;
 import org.apache.olingo.odata2.jpa.processor.api.ODataJPAContext;
 import org.apache.olingo.odata2.jpa.processor.api.ODataJPAServiceFactory;
 import org.apache.olingo.odata2.jpa.processor.api.exception.ODataJPARuntimeException;
+import org.baeldung.examples.olingo2.JerseyConfig.EntityManagerFilter;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.orm.jpa.EntityManagerFactoryUtils;
@@ -44,7 +47,6 @@ public class CarsODataJPAServiceFactory extends ODataJPAServiceFactory {
         setDetailErrors(true);
     }
 
-    
     /**
      * This method will be called by Olingo on every request to
      * initialize the ODataJPAContext that will be used. 
@@ -54,18 +56,18 @@ public class CarsODataJPAServiceFactory extends ODataJPAServiceFactory {
 
         log.info("[I32] >>> initializeODataJPAContext()");
         ODataJPAContext ctx = getODataJPAContext();
+        ODataContext octx = ctx.getODataContext();
+        HttpServletRequest request = (HttpServletRequest)octx.getParameter(ODataContext.HTTP_SERVLET_REQUEST_OBJECT);
+        EntityManager em = (EntityManager)request.getAttribute(EntityManagerFilter.EM_REQUEST_ATTRIBUTE);
                 
         // Here we're passing the EM that was created by the EntityManagerFilter (see JerseyConfig)
-        ctx.setEntityManager(new EntityManagerWrapper(EntityManagerHolder.getCurrentEntityManager()));
+        ctx.setEntityManager(new EntityManagerWrapper(em));
         ctx.setPersistenceUnitName("default");
         
         // We're managing the EM's lifecycle, so we must inform Olingo that it should not
         // try to manage transactions and/or persistence sessions
         ctx.setContainerManaged(true);                
-        
-                
         return ctx;
-        
     }
 
     static class EntityManagerWrapper implements EntityManager {
@@ -73,18 +75,21 @@ public class CarsODataJPAServiceFactory extends ODataJPAServiceFactory {
         private EntityManager delegate;
 
         public void persist(Object entity) {
-            log.info("[I68] persist: entity.class=" + entity.getClass().getSimpleName());
+            log.info("[I68] persist: entity.class=" + entity.getClass()
+                .getSimpleName());
             delegate.persist(entity);
-            //delegate.flush();
+            // delegate.flush();
         }
 
         public <T> T merge(T entity) {
-            log.info("[I74] merge: entity.class=" + entity.getClass().getSimpleName());
+            log.info("[I74] merge: entity.class=" + entity.getClass()
+                .getSimpleName());
             return delegate.merge(entity);
         }
 
         public void remove(Object entity) {
-            log.info("[I78] remove: entity.class=" + entity.getClass().getSimpleName());
+            log.info("[I78] remove: entity.class=" + entity.getClass()
+                .getSimpleName());
             delegate.remove(entity);
         }
 

apache-olingo/olingo2/src/main/java/org/baeldung/examples/olingo2/EntityManagerHolder.java

@@ -1,18 +0,0 @@
-package org.baeldung.examples.olingo2;
-
-import javax.persistence.EntityManager;
-
-public class EntityManagerHolder {
-    
-    private static ThreadLocal<EntityManager> currentEntityManager = new ThreadLocal<>();
-    
-    
-    public static void setCurrentEntityManager(EntityManager em) {
-        currentEntityManager.set(em);
-    }
-    
-    public static EntityManager getCurrentEntityManager() {
-        return currentEntityManager.get();
-    }
-
-}

apache-olingo/olingo2/src/main/java/org/baeldung/examples/olingo2/JerseyConfig.java

@@ -1,4 +1,4 @@
-package org.baeldung.examples.olingo2;
+    package org.baeldung.examples.olingo2;
 
 import java.io.IOException;
 
@@ -6,12 +6,14 @@ import javax.persistence.EntityManager;
 import javax.persistence.EntityManagerFactory;
 import javax.persistence.EntityTransaction;
 import javax.servlet.ServletContext;
+import javax.servlet.http.HttpServletRequest;
 import javax.ws.rs.ApplicationPath;
 import javax.ws.rs.Path;
 import javax.ws.rs.container.ContainerRequestContext;
 import javax.ws.rs.container.ContainerRequestFilter;
 import javax.ws.rs.container.ContainerResponseContext;
 import javax.ws.rs.container.ContainerResponseFilter;
+import javax.ws.rs.core.Context;
 import javax.ws.rs.ext.Provider;
 
 import org.apache.olingo.odata2.api.ODataServiceFactory;
@@ -59,9 +61,13 @@ public class JerseyConfig extends ResourceConfig {
     public static class EntityManagerFilter implements ContainerRequestFilter, ContainerResponseFilter {
 
         private static final Logger log = LoggerFactory.getLogger(EntityManagerFilter.class);
+        public static final String EM_REQUEST_ATTRIBUTE = EntityManagerFilter.class.getName() + "_ENTITY_MANAGER";
 
         private final EntityManagerFactory emf;
 
+        @Context
+        private HttpServletRequest httpRequest;
+
         public EntityManagerFilter(EntityManagerFactory emf) {
             this.emf = emf;
         }
@@ -70,11 +76,12 @@ public class JerseyConfig extends ResourceConfig {
         public void filter(ContainerRequestContext ctx) throws IOException {
             log.info("[I60] >>> filter");
             EntityManager em = this.emf.createEntityManager();
-            EntityManagerHolder.setCurrentEntityManager(em); 
+            httpRequest.setAttribute(EM_REQUEST_ATTRIBUTE, em);
 
             // Start a new transaction unless we have a simple GET
-            if ( !"GET".equalsIgnoreCase(ctx.getMethod())) {
+            if (!"GET".equalsIgnoreCase(ctx.getMethod())) {
-                em.getTransaction().begin();
+                em.getTransaction()
+                    .begin();
             }
         }
 
@@ -82,12 +89,12 @@ public class JerseyConfig extends ResourceConfig {
         public void filter(ContainerRequestContext requestContext, ContainerResponseContext responseContext) throws IOException {
 
             log.info("[I68] <<< filter");
+            EntityManager em = (EntityManager) httpRequest.getAttribute(EM_REQUEST_ATTRIBUTE);
 
-            EntityManager em = EntityManagerHolder.getCurrentEntityManager();
+            if (!"GET".equalsIgnoreCase(requestContext.getMethod())) {
-            if ( em != null && !"GET".equalsIgnoreCase(requestContext.getMethod())) {
                 EntityTransaction t = em.getTransaction();
-                if ( t.isActive()) {
+                if (t.isActive()) {
-                    if ( !t.getRollbackOnly()) {
+                    if (!t.getRollbackOnly()) {
                         t.commit();
                     }
                 }
@@ -99,7 +106,6 @@ public class JerseyConfig extends ResourceConfig {
 
     }
 
-    
     @Path("/")
     public static class CarsRootLocator extends ODataRootLocator {
 

apache-olingo/olingo2/src/main/resources/application.yml

@@ -1,3 +1,5 @@
+server:
+  port: 8180
   
 spring:
   jersey:

apache-olingo/olingo4/.gitignore

@@ -0,0 +1,29 @@
+HELP.md
+/target/
+!.mvn/wrapper/maven-wrapper.jar
+
+### STS ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+
+### IntelliJ IDEA ###
+.idea
+*.iws
+*.iml
+*.ipr
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+/build/
+
+### VS Code ###
+.vscode/

apache-olingo/olingo4/pom.xml

@@ -0,0 +1,95 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+	<parent>
+		<groupId>org.springframework.boot</groupId>
+		<artifactId>spring-boot-starter-parent</artifactId>
+		<version>2.1.3.RELEASE</version>
+		<relativePath /> <!-- lookup parent from repository -->
+	</parent>
+	<groupId>org.baeldung.examples.olingo4</groupId>
+	<artifactId>olingo4-sample</artifactId>
+	<version>0.0.1-SNAPSHOT</version>
+	<name>olingo4-sample</name>
+	<description>Sample Olingo 4 Project</description>
+
+	<properties>
+		<java.version>1.8</java.version>
+		<odata.version>4.5.0</odata.version>
+	</properties>
+
+	<dependencies>
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-data-jpa</artifactId>
+		</dependency>
+
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-configuration-processor</artifactId>
+			<optional>true</optional>
+		</dependency>
+
+		<dependency>
+			<groupId>com.h2database</groupId>
+			<artifactId>h2</artifactId>
+			<scope>runtime</scope>
+		</dependency>
+
+		<dependency>
+			<groupId>org.projectlombok</groupId>
+			<artifactId>lombok</artifactId>
+			<optional>true</optional>
+		</dependency>
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-test</artifactId>
+			<scope>test</scope>
+		</dependency>
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-web</artifactId>
+		</dependency>
+
+		<dependency>
+			<groupId>org.apache.olingo</groupId>
+			<artifactId>odata-server-api</artifactId>
+			<version>${odata.version}</version>
+		</dependency>
+		<dependency>
+			<groupId>org.apache.olingo</groupId>
+			<artifactId>odata-server-core</artifactId>
+			<version>${odata.version}</version>
+			<scope>runtime</scope>
+		</dependency>
+
+		<dependency>
+			<groupId>org.apache.olingo</groupId>
+			<artifactId>odata-commons-api</artifactId>
+			<version>${odata.version}</version>
+		</dependency>
+		<dependency>
+			<groupId>org.apache.olingo</groupId>
+			<artifactId>odata-commons-core</artifactId>
+			<version>${odata.version}</version>
+		</dependency>
+		
+		<dependency>
+			<groupId>commons-beanutils</groupId>
+			<artifactId>commons-beanutils</artifactId>
+			<version>1.9.3</version>
+		</dependency>
+	</dependencies>
+
+	<build>
+		<plugins>
+			<plugin>
+				<groupId>org.springframework.boot</groupId>
+				<artifactId>spring-boot-maven-plugin</artifactId>
+			</plugin>
+		</plugins>
+	</build>
+
+</project>

apache-olingo/olingo4/src/main/java/org/baeldung/examples/olingo4/DefaultODataFactory.java

@@ -0,0 +1,20 @@
+package org.baeldung.examples.olingo4;
+
+import org.apache.olingo.server.api.OData;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
+import org.springframework.stereotype.Component;
+
+/**
+ * Default implementation for ODataFactory 
+ * @author Philippe
+ *
+ */
+@Component
+public class DefaultODataFactory implements ODataFactory {
+
+    @Override
+    public OData newInstance() {
+        return OData.newInstance();
+    }
+
+}

apache-olingo/olingo4/src/main/java/org/baeldung/examples/olingo4/ODataFactory.java

@@ -0,0 +1,8 @@
+package org.baeldung.examples.olingo4;
+
+import org.apache.olingo.server.api.OData;
+
+public interface ODataFactory {
+
+    public OData newInstance();
+}

apache-olingo/olingo4/src/main/java/org/baeldung/examples/olingo4/ODataHttpHandlerFactory.java

@@ -0,0 +1,8 @@
+package org.baeldung.examples.olingo4;
+
+import org.apache.olingo.server.api.ODataHttpHandler;
+
+public interface ODataHttpHandlerFactory {
+
+    ODataHttpHandler newInstance();
+}

apache-olingo/olingo4/src/main/java/org/baeldung/examples/olingo4/ODataHttpHandlerFactoryImpl.java

@@ -0,0 +1,42 @@
+package org.baeldung.examples.olingo4;
+
+import java.util.Collections;
+import java.util.List;
+
+import org.apache.olingo.commons.api.edm.provider.CsdlEdmProvider;
+import org.apache.olingo.server.api.OData;
+import org.apache.olingo.server.api.ODataHttpHandler;
+import org.apache.olingo.server.api.ServiceMetadata;
+import org.apache.olingo.server.api.processor.Processor;
+
+import lombok.Builder;
+
+@Builder
+public class ODataHttpHandlerFactoryImpl implements ODataHttpHandlerFactory {
+    
+    
+    private final ODataFactory odataFactory;
+    private final CsdlEdmProvider edmProvider;
+    private final List<Processor> processors;
+
+    public ODataHttpHandlerFactoryImpl(ODataFactory odataFactory,CsdlEdmProvider edmProvider, List<Processor> processors) {
+        this.odataFactory = odataFactory;
+        this.edmProvider = edmProvider;
+        this.processors = processors;
+    }
+
+    @Override
+    public ODataHttpHandler newInstance() {
+        
+        OData odata = odataFactory.newInstance();
+        ServiceMetadata metadata = odata.createServiceMetadata(edmProvider, Collections.emptyList());
+        ODataHttpHandler handler = odata.createHandler(metadata);
+        
+        // Register all available processors
+        processors.forEach(p -> handler.register(p));
+        
+        
+        return handler;
+    }
+
+}

apache-olingo/olingo4/src/main/java/org/baeldung/examples/olingo4/ODataServiceConfiguration.java

@@ -0,0 +1,46 @@
+package org.baeldung.examples.olingo4;
+
+import java.util.List;
+
+import javax.persistence.EntityManagerFactory;
+import javax.servlet.http.HttpServlet;
+
+import org.apache.olingo.commons.api.edm.provider.CsdlEdmProvider;
+import org.apache.olingo.server.api.processor.Processor;
+import org.baeldung.examples.olingo4.ODataHttpHandlerFactoryImpl.ODataHttpHandlerFactoryImplBuilder;
+import org.springframework.boot.web.servlet.ServletRegistrationBean;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+@Configuration
+public class ODataServiceConfiguration {
+    
+    
+    @Bean
+    public ServletRegistrationBean<HttpServlet> odataServletRegistration(ODataHttpHandlerFactory factory, EntityManagerFactory emf) {
+        
+        ServletRegistrationBean bean = new ServletRegistrationBean(
+            odataServlet(factory,emf), 
+            "/odata/*");
+          bean.setLoadOnStartup(1);
+          return bean;
+    }
+    
+
+    @Bean
+    public HttpServlet odataServlet(ODataHttpHandlerFactory factory, EntityManagerFactory emf ) {
+        
+        return new ODataServlet(factory,emf);
+    }
+    
+    
+    @Bean
+    public ODataHttpHandlerFactory httpHandlerFactory(CsdlEdmProvider edmProvider, ODataFactory odataFactory, List<Processor> processors) {
+        return new ODataHttpHandlerFactoryImplBuilder()
+            .edmProvider(edmProvider)
+            .odataFactory(odataFactory)
+            .processors(processors)
+            .build();
+    }
+
+}

apache-olingo/olingo4/src/main/java/org/baeldung/examples/olingo4/ODataServlet.java

@@ -0,0 +1,38 @@
+/**
+ * 
+ */
+package org.baeldung.examples.olingo4;
+
+import java.io.IOException;
+
+import javax.persistence.EntityManager;
+import javax.persistence.EntityManagerFactory;
+import javax.persistence.EntityTransaction;
+import javax.servlet.ServletException;
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+import org.apache.olingo.server.api.ODataHttpHandler;
+
+/**
+ * @author Philippe
+ *
+ */
+public class ODataServlet extends HttpServlet {
+
+    private static final long serialVersionUID = 1L;
+    private final ODataHttpHandlerFactory odataHttpHandlerFactory;
+    
+    
+    public ODataServlet(ODataHttpHandlerFactory factory, EntityManagerFactory emf) {
+        this.odataHttpHandlerFactory = factory;
+    }
+
+    @Override
+    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
+
+        ODataHttpHandler handler = odataHttpHandlerFactory.newInstance();
+        handler.process(req, resp);
+    }
+}

apache-olingo/olingo4/src/main/java/org/baeldung/examples/olingo4/Olingo4SampleApplication.java

@@ -0,0 +1,13 @@
+package org.baeldung.examples.olingo4;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class Olingo4SampleApplication {
+
+    public static void main(String[] args) {
+        SpringApplication.run(Olingo4SampleApplication.class, args);
+    }
+
+}

apache-olingo/olingo4/src/main/java/org/baeldung/examples/olingo4/domain/CarMaker.java

@@ -0,0 +1,36 @@
+package org.baeldung.examples.olingo4.domain;
+
+import java.util.List;
+
+import javax.persistence.CascadeType;
+import javax.persistence.Column;
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.GenerationType;
+import javax.persistence.Id;
+import javax.persistence.OneToMany;
+import javax.persistence.Table;
+import javax.validation.constraints.NotNull;
+
+import lombok.Data;
+
+@Entity
+@Data
+@Table(name="car_maker")
+public class CarMaker {
+    
+    @Id
+    @GeneratedValue(strategy=GenerationType.IDENTITY)    
+    private Long id;
+    
+    @NotNull
+    @Column(name="name")
+    private String name;
+    
+    @OneToMany(mappedBy="maker",
+      orphanRemoval = true,
+      cascade=CascadeType.ALL)
+    private List<CarModel> models;
+    
+
+}

apache-olingo/olingo4/src/main/java/org/baeldung/examples/olingo4/domain/CarModel.java

@@ -0,0 +1,38 @@
+package org.baeldung.examples.olingo4.domain;
+
+
+import javax.persistence.Entity;
+import javax.persistence.FetchType;
+import javax.persistence.GeneratedValue;
+import javax.persistence.GenerationType;
+import javax.persistence.Id;
+import javax.persistence.JoinColumn;
+import javax.persistence.ManyToOne;
+import javax.persistence.Table;
+import javax.validation.constraints.NotNull;
+
+import lombok.Data;
+
+@Entity
+@Data
+@Table(name="car_model")
+public class CarModel {
+
+    @Id
+    @GeneratedValue(strategy=GenerationType.AUTO)
+    private Long id;
+    
+    @NotNull
+    private String name;
+    
+    @NotNull
+    private Integer year;
+    
+    @NotNull
+    private String sku;
+    
+    @ManyToOne(optional=false, fetch= FetchType.LAZY)
+    @JoinColumn(name="maker_fk")
+    private CarMaker maker;
+
+}

apache-olingo/olingo4/src/main/java/org/baeldung/examples/olingo4/edm/EdmTypeMapper.java

@@ -0,0 +1,46 @@
+package org.baeldung.examples.olingo4.edm;
+
+import java.util.Collections;
+import java.util.Date;
+import java.util.Map;
+import java.util.UUID;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+import java.sql.Time;
+import java.util.AbstractMap.SimpleEntry;
+
+import org.apache.olingo.commons.api.edm.EdmPrimitiveTypeKind;
+import org.springframework.stereotype.Component;
+
+@Component
+public class EdmTypeMapper {
+
+    public EdmPrimitiveTypeKind java2edm(Class<?> clazz) {
+        EdmPrimitiveTypeKind result = java2edm.get(clazz);
+        if ( result == null ) {
+            throw new IllegalArgumentException("[E19] Unsupported class mapping: class=" + clazz);
+        }
+        else {
+            return result;
+        }
+    }
+    
+    // Static map used generate attribute metadada based on Java types
+    static Map<Class<?>,EdmPrimitiveTypeKind> java2edm = Collections
+      .unmodifiableMap(Stream.of(
+        new SimpleEntry<>(Boolean.class,EdmPrimitiveTypeKind.Boolean),
+        new SimpleEntry<>(Byte.class,EdmPrimitiveTypeKind.SByte),
+        new SimpleEntry<>(Date.class,EdmPrimitiveTypeKind.Date),
+        new SimpleEntry<>(Time.class,EdmPrimitiveTypeKind.TimeOfDay),
+        new SimpleEntry<>(Number.class,EdmPrimitiveTypeKind.Decimal),
+        new SimpleEntry<>(Float.class,EdmPrimitiveTypeKind.Single),
+        new SimpleEntry<>(Double.class,EdmPrimitiveTypeKind.Double),
+        new SimpleEntry<>(UUID.class,EdmPrimitiveTypeKind.Guid),
+        new SimpleEntry<>(Short.class,EdmPrimitiveTypeKind.Int16),
+        new SimpleEntry<>(Integer.class,EdmPrimitiveTypeKind.Int32),
+        new SimpleEntry<>(Long.class,EdmPrimitiveTypeKind.Int64),
+        new SimpleEntry<>(String.class,EdmPrimitiveTypeKind.String)
+      
+      ).collect(Collectors.toMap((e)-> e.getKey(),(e)-> e.getValue())));
+
+}

apache-olingo/olingo4/src/main/java/org/baeldung/examples/olingo4/edm/JpaEdmProvider.java

@@ -0,0 +1,237 @@
+package org.baeldung.examples.olingo4.edm;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.stream.Collectors;
+
+import javax.persistence.EntityManagerFactory;
+import javax.persistence.metamodel.Attribute.PersistentAttributeType;
+import javax.persistence.metamodel.EntityType;
+import javax.persistence.metamodel.Metamodel;
+import javax.persistence.metamodel.PluralAttribute;
+import javax.persistence.metamodel.SingularAttribute;
+
+import org.apache.olingo.commons.api.edm.FullQualifiedName;
+import org.apache.olingo.commons.api.edm.provider.CsdlAbstractEdmProvider;
+import org.apache.olingo.commons.api.edm.provider.CsdlEntityContainer;
+import org.apache.olingo.commons.api.edm.provider.CsdlEntityContainerInfo;
+import org.apache.olingo.commons.api.edm.provider.CsdlEntitySet;
+import org.apache.olingo.commons.api.edm.provider.CsdlEntityType;
+import org.apache.olingo.commons.api.edm.provider.CsdlNavigationProperty;
+import org.apache.olingo.commons.api.edm.provider.CsdlProperty;
+import org.apache.olingo.commons.api.edm.provider.CsdlPropertyRef;
+import org.apache.olingo.commons.api.edm.provider.CsdlSchema;
+import org.apache.olingo.commons.api.ex.ODataException;
+import org.springframework.stereotype.Component;
+
+@Component
+public class JpaEdmProvider extends CsdlAbstractEdmProvider {
+
+    EntityManagerFactory emf;
+
+    //
+    private EdmTypeMapper typeMapper;
+
+    // Service Namespace
+    public static final String NAMESPACE = "OData.Demo";
+
+    // EDM Container
+    public static final String CONTAINER_NAME = "Cars";
+    public static final FullQualifiedName CONTAINER = new FullQualifiedName(NAMESPACE, CONTAINER_NAME);
+
+    public JpaEdmProvider(EntityManagerFactory emf, EdmTypeMapper mapper) {
+        this.emf = emf;
+        this.typeMapper = mapper;
+    }
+
+    /* (non-Javadoc)
+     * @see org.apache.olingo.commons.api.edm.provider.CsdlAbstractEdmProvider#getEntitySet(org.apache.olingo.commons.api.edm.FullQualifiedName, java.lang.String)
+     */
+    @Override
+    public CsdlEntitySet getEntitySet(FullQualifiedName entityContainer, String entitySetName) throws ODataException {
+
+        if (entityContainer.equals(CONTAINER)) {
+
+            EntityType<?> e = emf.getMetamodel()
+                .getEntities()
+                .stream()
+                .filter((ent) -> (ent.getName() + "s")
+                    .equals(entitySetName))
+                .findFirst()
+                .orElse(null);
+
+            if (e != null) {
+                CsdlEntitySet entitySet = new CsdlEntitySet();
+                entitySet.setName(entitySetName);
+                entitySet.setType(new FullQualifiedName(NAMESPACE, e.getName()));
+                return entitySet;
+            }
+        }
+
+        return null;
+    }
+
+    /* (non-Javadoc)
+     * @see org.apache.olingo.commons.api.edm.provider.CsdlAbstractEdmProvider#getEntityContainerInfo(org.apache.olingo.commons.api.edm.FullQualifiedName)
+     */
+    @Override
+    public CsdlEntityContainerInfo getEntityContainerInfo(FullQualifiedName entityContainerName) throws ODataException {
+
+        // This method is invoked when displaying the Service Document at e.g. http://localhost:8080/DemoService/DemoService.svc
+        if (entityContainerName == null || entityContainerName.equals(CONTAINER)) {
+            CsdlEntityContainerInfo entityContainerInfo = new CsdlEntityContainerInfo();
+            entityContainerInfo.setContainerName(CONTAINER);
+            return entityContainerInfo;
+        }
+
+        return null;
+    }
+
+    /* (non-Javadoc)
+     * @see org.apache.olingo.commons.api.edm.provider.CsdlAbstractEdmProvider#getSchemas()
+     */
+    @Override
+    public List<CsdlSchema> getSchemas() throws ODataException {
+        // create Schema
+        CsdlSchema schema = new CsdlSchema();
+        schema.setNamespace(NAMESPACE);
+
+        // add EntityTypes
+        List<CsdlEntityType> entityTypes = emf.getMetamodel()
+            .getEntities()
+            .stream()
+            .map((e) -> {
+                try {
+                    return getEntityType(new FullQualifiedName(NAMESPACE, e.getName()));
+                } catch (ODataException oe) {
+                    throw new RuntimeException(oe);
+                }
+            })
+            .collect(Collectors.toList());
+
+        schema.setEntityTypes(entityTypes);
+
+        // add EntityContainer
+        schema.setEntityContainer(getEntityContainer());
+
+        // finally
+        List<CsdlSchema> schemas = new ArrayList<CsdlSchema>();
+        schemas.add(schema);
+
+        return schemas;
+    }
+
+    /* (non-Javadoc)
+     * @see org.apache.olingo.commons.api.edm.provider.CsdlAbstractEdmProvider#getEntityContainer()
+     */
+    @Override
+    public CsdlEntityContainer getEntityContainer() throws ODataException {
+        
+        
+        // add EntityTypes
+        List<CsdlEntitySet> entitySets = emf.getMetamodel()
+            .getEntities()
+            .stream()
+            .map((e) -> {
+                try {
+                    // Here we use a simple mapping strategy to map entity types to entity set names:
+                    // 
+                    return getEntitySet(CONTAINER, e.getName() + "s");
+                } catch (ODataException oe) {
+                    throw new RuntimeException(oe);
+                }
+            })
+            .collect(Collectors.toList());
+        
+        // create EntityContainer
+        CsdlEntityContainer entityContainer = new CsdlEntityContainer();
+        entityContainer.setName(CONTAINER_NAME);
+        entityContainer.setEntitySets(entitySets);
+
+        return entityContainer;
+    }
+
+    @Override
+    public CsdlEntityType getEntityType(FullQualifiedName entityTypeName) throws ODataException {
+
+        Metamodel mm = emf.getMetamodel();
+
+        CsdlEntityType result = null;
+
+        result = mm.getEntities()
+            .stream()
+            .filter(et -> entityTypeName.equals(new FullQualifiedName(NAMESPACE, et.getName())))
+            .map(et -> buildODataType(et))
+            .findFirst()
+            .orElse(null);
+
+        return result;
+        
+    }
+
+    /**
+     * Maps a JPA type to its OData counterpart.
+     * @param et
+     * @return
+     */
+    protected CsdlEntityType buildODataType(EntityType<?> et) {
+
+        CsdlEntityType result = new CsdlEntityType();
+        result.setName(et.getName());
+
+        // Process simple properties
+        List<CsdlProperty> properties = et.getDeclaredSingularAttributes()
+            .stream()
+            .filter(attr -> attr.getPersistentAttributeType() == PersistentAttributeType.BASIC)
+            .map(attr -> buildBasicAttribute(et, attr))
+            .collect(Collectors.toList());
+
+        result.setProperties(properties);
+
+        // Process Ids
+        List<CsdlPropertyRef> ids = et.getDeclaredSingularAttributes()
+            .stream()
+            .filter(attr -> attr.getPersistentAttributeType() == PersistentAttributeType.BASIC && attr.isId())
+            .map(attr -> buildRefAttribute(et, attr))
+            .collect(Collectors.toList());
+
+        result.setKey(ids);
+
+        // Process navs
+        List<CsdlNavigationProperty> navs = et.getDeclaredPluralAttributes()
+            .stream()
+            .map(attr -> buildNavAttribute(et, attr))
+            .collect(Collectors.toList());
+        result.setNavigationProperties(navs);
+
+        return result;
+    }
+
+    private CsdlProperty buildBasicAttribute(EntityType<?> et, SingularAttribute<?, ?> attr) {
+
+        CsdlProperty p = new CsdlProperty().setName(attr.getName())
+            .setType(typeMapper.java2edm(attr.getJavaType())
+                .getFullQualifiedName())
+            .setNullable(et.getDeclaredSingularAttribute(attr.getName())
+                .isOptional());
+
+        return p;
+    }
+
+    private CsdlPropertyRef buildRefAttribute(EntityType<?> et, SingularAttribute<?, ?> attr) {
+
+        CsdlPropertyRef p = new CsdlPropertyRef().setName(attr.getName());
+
+        return p;
+    }
+
+    private CsdlNavigationProperty buildNavAttribute(EntityType<?> et, PluralAttribute<?, ?, ?> attr) {
+
+        CsdlNavigationProperty p = new CsdlNavigationProperty().setName(attr.getName())
+            .setType(new FullQualifiedName(NAMESPACE, attr.getBindableJavaType().getSimpleName()))
+            .setNullable(false); // for now
+
+        return p;
+    }
+
+}

apache-olingo/olingo4/src/main/java/org/baeldung/examples/olingo4/processor/JpaEntityCollectionProcessor.java

@@ -0,0 +1,185 @@
+package org.baeldung.examples.olingo4.processor;
+
+import java.io.ByteArrayInputStream;
+import java.io.InputStream;
+import java.lang.reflect.InvocationTargetException;
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.util.List;
+
+import javax.persistence.EntityManagerFactory;
+import javax.persistence.metamodel.EntityType;
+import javax.persistence.metamodel.SingularAttribute;
+
+import org.apache.commons.beanutils.PropertyUtils;
+import org.apache.olingo.commons.api.data.ContextURL;
+import org.apache.olingo.commons.api.data.Entity;
+import org.apache.olingo.commons.api.data.EntityCollection;
+import org.apache.olingo.commons.api.data.Property;
+import org.apache.olingo.commons.api.data.ValueType;
+import org.apache.olingo.commons.api.edm.EdmEntitySet;
+import org.apache.olingo.commons.api.edm.EdmEntityType;
+import org.apache.olingo.commons.api.ex.ODataRuntimeException;
+import org.apache.olingo.commons.api.format.ContentType;
+import org.apache.olingo.commons.api.http.HttpHeader;
+import org.apache.olingo.commons.api.http.HttpStatusCode;
+import org.apache.olingo.server.api.OData;
+import org.apache.olingo.server.api.ODataApplicationException;
+import org.apache.olingo.server.api.ODataLibraryException;
+import org.apache.olingo.server.api.ODataRequest;
+import org.apache.olingo.server.api.ODataResponse;
+import org.apache.olingo.server.api.ServiceMetadata;
+import org.apache.olingo.server.api.processor.CountEntityCollectionProcessor;
+import org.apache.olingo.server.api.processor.EntityCollectionProcessor;
+import org.apache.olingo.server.api.serializer.EntityCollectionSerializerOptions;
+import org.apache.olingo.server.api.serializer.ODataSerializer;
+import org.apache.olingo.server.api.serializer.SerializerResult;
+import org.apache.olingo.server.api.uri.UriInfo;
+import org.apache.olingo.server.api.uri.UriResource;
+import org.apache.olingo.server.api.uri.UriResourceEntitySet;
+import org.baeldung.examples.olingo4.repository.RepositoryRegistry;
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.stereotype.Component;
+
+@Component
+public class JpaEntityCollectionProcessor implements CountEntityCollectionProcessor {
+
+    private OData odata;
+    private ServiceMetadata serviceMetadata;
+    private EntityManagerFactory emf;
+    private RepositoryRegistry repositoryRegistry;
+
+    public JpaEntityCollectionProcessor(EntityManagerFactory emf, RepositoryRegistry repositoryRegistry) {
+        this.emf = emf;
+        this.repositoryRegistry = repositoryRegistry;
+    }
+
+    @Override
+    public void init(OData odata, ServiceMetadata serviceMetadata) {
+        this.odata = odata;
+        this.serviceMetadata = serviceMetadata;
+    }
+
+    @Override
+    public void readEntityCollection(ODataRequest request, ODataResponse response, UriInfo uriInfo, ContentType responseFormat) throws ODataApplicationException, ODataLibraryException {
+
+        // 1st we have retrieve the requested EntitySet from the uriInfo object (representation of the parsed service URI)
+        List<UriResource> resourcePaths = uriInfo.getUriResourceParts();
+        UriResourceEntitySet uriResourceEntitySet = (UriResourceEntitySet) resourcePaths.get(0); // in our example, the first segment is the EntitySet
+        EdmEntitySet edmEntitySet = uriResourceEntitySet.getEntitySet();
+
+        // 2nd: fetch the data from backend for this requested EntitySetName
+        // it has to be delivered as EntitySet object
+        EntityCollection entitySet = getData(edmEntitySet, uriInfo);
+
+        // 3rd: create a serializer based on the requested format (json)
+        ODataSerializer serializer = odata.createSerializer(responseFormat);
+
+        // 4th: Now serialize the content: transform from the EntitySet object to InputStream
+        EdmEntityType edmEntityType = edmEntitySet.getEntityType();
+        ContextURL contextUrl = ContextURL.with()
+            .entitySet(edmEntitySet)
+            .build();
+
+        final String id = request.getRawBaseUri() + "/" + edmEntitySet.getName();
+        EntityCollectionSerializerOptions opts = EntityCollectionSerializerOptions.with()
+            .id(id)
+            .contextURL(contextUrl)
+            .build();
+        SerializerResult serializerResult = serializer.entityCollection(serviceMetadata, edmEntityType, entitySet, opts);
+        InputStream serializedContent = serializerResult.getContent();
+
+        // Finally: configure the response object: set the body, headers and status code
+        response.setContent(serializedContent);
+        response.setStatusCode(HttpStatusCode.OK.getStatusCode());
+        response.setHeader(HttpHeader.CONTENT_TYPE, responseFormat.toContentTypeString());
+
+    }
+
+    @Override
+    public void countEntityCollection(ODataRequest request, ODataResponse response, UriInfo uriInfo) throws ODataApplicationException, ODataLibraryException {
+
+        // 1st we have retrieve the requested EntitySet from the uriInfo object (representation of the parsed service URI)
+        List<UriResource> resourcePaths = uriInfo.getUriResourceParts();
+        UriResourceEntitySet uriResourceEntitySet = (UriResourceEntitySet) resourcePaths.get(0); // in our example, the first segment is the EntitySet
+        EdmEntitySet edmEntitySet = uriResourceEntitySet.getEntitySet();
+
+        // 2nd: fetch the data from backend for this requested EntitySetName
+        Long count = getCount(edmEntitySet, uriInfo);
+
+        // Finally: configure the response object: set the body, headers and status code
+        response.setContent(new ByteArrayInputStream(count.toString()
+            .getBytes()));
+        response.setStatusCode(HttpStatusCode.OK.getStatusCode());
+        response.setHeader(HttpHeader.CONTENT_TYPE, "text/plain");
+
+    }
+
+    private EntityCollection getData(EdmEntitySet edmEntitySet, UriInfo uriInfo) {
+
+        EdmEntityType type = edmEntitySet.getEntityType();
+        JpaRepository<?, ?> repo = repositoryRegistry.getRepositoryForEntity(type);
+        EntityCollection result = new EntityCollection();
+
+        repo.findAll()
+            .stream()
+            .forEach((it) -> result.getEntities()
+                .add(map2entity(edmEntitySet, it)));
+
+        return result;
+    }
+
+    private Entity map2entity(EdmEntitySet edmEntitySet, Object entry) {
+
+        EntityType<?> et = emf.getMetamodel()
+            .entity(entry.getClass());
+
+
+        Entity e = new Entity();
+        try {
+            // First, we set the entity's primary key
+            
+            // Now map all properties
+            et.getDeclaredSingularAttributes().stream()
+              .forEach( (attr) -> {
+                 if ( !attr.isAssociation()) {
+                     Object v = getPropertyValue(entry,attr.getName());
+                     Property p = new Property(null, attr.getName(),ValueType.PRIMITIVE,v);
+                     e.addProperty(p);
+
+                     if ( attr.isId()) {
+                         e.setId(createId(edmEntitySet.getName(),v));                     
+                     }                     
+                 }
+                 
+              });
+            
+        } catch (Exception ex) {
+            throw new ODataRuntimeException("[E141] Unable to create OData entity", ex);
+        }
+
+        return e;
+    }
+    
+    private Object getPropertyValue(Object entry, String name) {
+        try {
+            return PropertyUtils.getProperty(entry,name);
+        } catch (IllegalAccessException | InvocationTargetException | NoSuchMethodException e) {
+            throw new ODataRuntimeException("[E141] Unable to read property from entity, property=" + name, e);
+        }
+    }
+
+    private URI createId(String entitySetName, Object id)  {
+        try {
+            return new URI(entitySetName + "(" + String.valueOf(id) + ")");
+        } catch (URISyntaxException e) {
+            throw new ODataRuntimeException("[E177] Unable to create URI", e);
+        }
+    }
+
+    private Long getCount(EdmEntitySet edmEntitySet, UriInfo uriInfo) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+}

apache-olingo/olingo4/src/main/java/org/baeldung/examples/olingo4/repository/CarMakerRepository.java

@@ -0,0 +1,12 @@
+package org.baeldung.examples.olingo4.repository;
+
+import org.baeldung.examples.olingo4.domain.CarMaker;
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
+import org.springframework.stereotype.Repository;
+
+@Repository
+public interface CarMakerRepository extends JpaRepository<CarMaker, Long>, JpaSpecificationExecutor<CarMaker>, EdmEntityRepository {
+
+    public default String getEdmEntityName() { return CarMaker.class.getSimpleName();}
+}

apache-olingo/olingo4/src/main/java/org/baeldung/examples/olingo4/repository/CarModelRepository.java

@@ -0,0 +1,13 @@
+package org.baeldung.examples.olingo4.repository;
+
+import org.baeldung.examples.olingo4.domain.CarModel;
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
+import org.springframework.stereotype.Repository;
+
+@Repository
+public interface CarModelRepository extends JpaRepository<CarModel, Long>, JpaSpecificationExecutor<CarModel>,EdmEntityRepository {
+
+    public default String getEdmEntityName() { return CarModel.class.getSimpleName();}
+
+}

apache-olingo/olingo4/src/main/java/org/baeldung/examples/olingo4/repository/EdmEntityRepository.java

@@ -0,0 +1,15 @@
+/**
+ * 
+ */
+package org.baeldung.examples.olingo4.repository;
+
+
+/**
+ * @author Philippe
+ *
+ */
+public interface EdmEntityRepository {
+    
+    public String getEdmEntityName();
+
+}

apache-olingo/olingo4/src/main/java/org/baeldung/examples/olingo4/repository/RepositoryRegistry.java

@@ -0,0 +1,28 @@
+package org.baeldung.examples.olingo4.repository;
+
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import org.apache.olingo.commons.api.edm.EdmEntityType;
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.stereotype.Component;
+
+@Component
+public class RepositoryRegistry {
+    
+    private Map<String,JpaRepository<?,?>> repositoriesByClassName = new HashMap<>();
+
+    public RepositoryRegistry(List<EdmEntityRepository> allRepositories) {
+        
+        allRepositories.stream().forEach((r) ->  
+        repositoriesByClassName.put(r.getEdmEntityName(),(JpaRepository<?,?>)r));
+        
+    }
+    
+    
+    public JpaRepository<?, ?> getRepositoryForEntity(EdmEntityType entityType) {        
+        JpaRepository<?, ?> repo = repositoriesByClassName.get(entityType.getName());
+        return repo;
+    }
+}

apache-olingo/olingo4/src/main/resources/application.properties

@@ -0,0 +1,6 @@
+spring:    
+  jpa:
+    show-sql: true
+    open-in-view: false
+    hibernate:
+      ddl-auto: update

apache-olingo/olingo4/src/main/resources/data.sql

@@ -0,0 +1,12 @@
+insert into car_maker(id,name) values (1,'Special Motors');
+insert into car_maker(id,name) values (2,'BWM');
+insert into car_maker(id,name) values (3,'Dolores');
+
+insert into car_model(id,maker_fk,name,sku,year) values(1,1,'Muze','SM001',2018);
+insert into car_model(id,maker_fk,name,sku,year) values(2,1,'Empada','SM002',2008);
+
+insert into car_model(id,maker_fk,name,sku,year) values(4,2,'BWM-100','BWM100',2008);
+insert into car_model(id,maker_fk,name,sku,year) values(5,2,'BWM-200','BWM200',2009);
+insert into car_model(id,maker_fk,name,sku,year) values(6,2,'BWM-300','BWM300',2008);
+
+alter sequence hibernate_sequence restart with 100;

apache-olingo/olingo4/src/test/java/org/baeldung/examples/olingo4/Olingo4SampleApplicationTests.java

@@ -0,0 +1,16 @@
+package org.baeldung.examples.olingo4;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.test.context.junit4.SpringRunner;
+
+@RunWith(SpringRunner.class)
+@SpringBootTest
+public class Olingo4SampleApplicationTests {
+
+	@Test
+	public void contextLoads() {
+	}
+
+}