Work on graph QL support

hapi-fhir-base/src/main/java/ca/uhn/fhir/rest/annotation/GraphQL.java

@@ -0,0 +1,15 @@
+package ca.uhn.fhir.rest.annotation;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * A method annotated with this annotation will be treated as a GraphQL implementation
+ * method
+ */
+@Retention(RetentionPolicy.RUNTIME)
+@Target(value= ElementType.METHOD)
+public @interface GraphQL {
+}

hapi-fhir-base/src/main/java/ca/uhn/fhir/rest/annotation/GraphQLQuery.java

@@ -0,0 +1,22 @@
+package ca.uhn.fhir.rest.annotation;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * This annotation should be placed on the parameter of a
+ * {@link GraphQL @GraphQL} annotated method. The given
+ * parameter will be populated with the specific graphQL
+ * query being requested.
+ *
+ * <p>
+ *    This parameter should be of type {@link String}
+ * </p>
+ */
+@Retention(RetentionPolicy.RUNTIME)
+@Target(ElementType.PARAMETER)
+public @interface GraphQLQuery {
+	// ignore
+}

hapi-fhir-base/src/main/java/ca/uhn/fhir/rest/api/Constants.java

@@ -171,6 +171,7 @@ public class Constants {
 	public static final String URL_TOKEN_HISTORY = "_history";
 	public static final String URL_TOKEN_METADATA = "metadata";
 	public static final String OO_INFOSTATUS_PROCESSING = "processing";
+	public static final String PARAM_GRAPHQL_QUERY = "query";
 
 	static {
 		CHARSET_UTF8 = Charset.forName(CHARSET_NAME_UTF8);

hapi-fhir-base/src/main/java/ca/uhn/fhir/rest/api/RestOperationTypeEnum.java

@@ -37,6 +37,14 @@ public enum RestOperationTypeEnum {
 
 	GET_PAGE("get-page"),
 
+	/**
+	 * <b>
+	 * Use this value with caution, this may
+	 * change as the GraphQL interface matures
+	 * </b>
+	 */
+	GRAPHQL_REQUEST("graphql-request"),
+
 	/**
 	 * E.g. $everything, $validate, etc.
 	 */

hapi-fhir-server/src/main/java/ca/uhn/fhir/rest/api/server/IFhirVersionServer.java

@@ -1,11 +1,10 @@
 package ca.uhn.fhir.rest.api.server;
 
-import org.hl7.fhir.instance.model.api.IBaseResource;
-
 import ca.uhn.fhir.model.api.IFhirVersion;
 import ca.uhn.fhir.rest.server.IResourceProvider;
 import ca.uhn.fhir.rest.server.IServerConformanceProvider;
 import ca.uhn.fhir.rest.server.RestfulServer;
+import org.hl7.fhir.instance.model.api.IBaseResource;
 
 /**
  * This class is the server specific equivalent to {@link IFhirVersion}

hapi-fhir-server/src/main/java/ca/uhn/fhir/rest/server/RestfulServerUtils.java

@@ -543,7 +543,7 @@ public class RestfulServerUtils {
 	public static Object streamResponseAsResource(IRestfulServerDefaults theServer, IBaseResource theResource, Set<SummaryEnum> theSummaryMode, int theStausCode, String theStatusMessage,
 			boolean theAddContentLocationHeader, boolean respondGzip, RequestDetails theRequestDetails, IIdType theOperationResourceId, IPrimitiveType<Date> theOperationResourceLastUpdated)
 			throws IOException {
-		IRestfulResponse restUtil = theRequestDetails.getResponse();
+		IRestfulResponse response = theRequestDetails.getResponse();
 
 		// Determine response encoding
 		ResponseEncoding responseEncoding = RestfulServerUtils.determineResponseEncodingNoDefault(theRequestDetails, theServer.getDefaultResponseEncoding());
@@ -561,14 +561,14 @@ public class RestfulServerUtils {
 
 		if (theAddContentLocationHeader && fullId != null) {
 			if (theServer.getFhirContext().getVersion().getVersion().isOlderThan(FhirVersionEnum.DSTU3)) {
-				restUtil.addHeader(Constants.HEADER_CONTENT_LOCATION, fullId.getValue());
+				response.addHeader(Constants.HEADER_CONTENT_LOCATION, fullId.getValue());
 			}
-			restUtil.addHeader(Constants.HEADER_LOCATION, fullId.getValue());
+			response.addHeader(Constants.HEADER_LOCATION, fullId.getValue());
 		}
 
 		if (theServer.getETagSupport() == ETagSupportEnum.ENABLED) {
 			if (fullId != null && fullId.hasVersionIdPart()) {
-				restUtil.addHeader(Constants.HEADER_ETAG, "W/\"" + fullId.getVersionIdPart() + '"');
+				response.addHeader(Constants.HEADER_ETAG, "W/\"" + fullId.getVersionIdPart() + '"');
 			}
 		}
 
@@ -582,9 +582,9 @@ public class RestfulServerUtils {
 			}
 			// Force binary resources to download - This is a security measure to prevent
 			// malicious images or HTML blocks being served up as content.
-			restUtil.addHeader(Constants.HEADER_CONTENT_DISPOSITION, "Attachment;");
+			response.addHeader(Constants.HEADER_CONTENT_DISPOSITION, "Attachment;");
 
-			return restUtil.sendAttachmentResponse(bin, theStausCode, contentType);
+			return response.sendAttachmentResponse(bin, theStausCode, contentType);
 		}
 
 		// Ok, we're not serving a binary resource, so apply default encoding
@@ -615,7 +615,7 @@ public class RestfulServerUtils {
 			lastUpdated = extractLastUpdatedFromResource(theResource);
 		}
 		if (lastUpdated != null && lastUpdated.isEmpty() == false) {
-			restUtil.addHeader(Constants.HEADER_LAST_MODIFIED, DateUtils.formatDate(lastUpdated.getValue()));
+			response.addHeader(Constants.HEADER_LAST_MODIFIED, DateUtils.formatDate(lastUpdated.getValue()));
 		}
 
 		/*
@@ -631,7 +631,7 @@ public class RestfulServerUtils {
 		}
 		String charset = Constants.CHARSET_NAME_UTF8;
 
-		Writer writer = restUtil.getResponseWriter(theStausCode, theStatusMessage, contentType, charset, respondGzip);
+		Writer writer = response.getResponseWriter(theStausCode, theStatusMessage, contentType, charset, respondGzip);
 		if (theResource == null) {
 			// No response is being returned
 		} else if (encodingDomainResourceAsText && theResource instanceof IResource) {
@@ -641,7 +641,7 @@ public class RestfulServerUtils {
 			parser.encodeResourceToWriter(theResource, writer);
 		}
 		//FIXME resource leak
-		return restUtil.sendWriterResponse(theStausCode, contentType, charset, writer);
+		return response.sendWriterResponse(theStausCode, contentType, charset, writer);
 	}
 
 	public static Integer tryToExtractNamedParameter(RequestDetails theRequest, String theParamName) {

hapi-fhir-server/src/main/java/ca/uhn/fhir/rest/server/graphql/GraphQLProviderR4.java

@@ -0,0 +1,9 @@
+package ca.uhn.fhir.rest.server.graphql;
+
+import ca.uhn.fhir.rest.annotation.Operation;
+
+public class GraphQLProviderR4 {
+
+
+
+}

hapi-fhir-server/src/main/java/ca/uhn/fhir/rest/server/method/BaseMethodBinding.java

@@ -92,25 +92,15 @@ public abstract class BaseMethodBinding<T> {
 		return parser;
 	}
 
-	protected IParser createAppropriateParserForParsingServerRequest(RequestDetails theRequest) {
+	protected Object[] createMethodParams(RequestDetails theRequest) {
-		String contentTypeHeader = theRequest.getHeader(Constants.HEADER_CONTENT_TYPE);
+		Object[] params = new Object[getParameters().size()];
-		EncodingEnum encoding;
+		for (int i = 0; i < getParameters().size(); i++) {
-		if (isBlank(contentTypeHeader)) {
+			IParameter param = getParameters().get(i);
-			encoding = EncodingEnum.XML;
+			if (param != null) {
-		} else {
+				params[i] = param.translateQueryParametersIntoServerArgument(theRequest, this);
-			int semicolon = contentTypeHeader.indexOf(';');
-			if (semicolon != -1) {
-				contentTypeHeader = contentTypeHeader.substring(0, semicolon);
 			}
-			encoding = EncodingEnum.forContentType(contentTypeHeader);
 		}
-
+		return params;
-		if (encoding == null) {
-			throw new InvalidRequestException("Request contins non-FHIR conent-type header value: " + contentTypeHeader);
-		}
-
-		IParser parser = encoding.newParser(getContext());
-		return parser;
 	}
 
 	protected Object[] createParametersForServerRequest(RequestDetails theRequest) {
@@ -345,9 +335,10 @@ public abstract class BaseMethodBinding<T> {
 		Operation operation = theMethod.getAnnotation(Operation.class);
 		GetPage getPage = theMethod.getAnnotation(GetPage.class);
 		Patch patch = theMethod.getAnnotation(Patch.class);
+		GraphQL graphQL = theMethod.getAnnotation(GraphQL.class);
 
 		// ** if you add another annotation above, also add it to the next line:
-		if (!verifyMethodHasZeroOrOneOperationAnnotation(theMethod, read, search, conformance, create, update, delete, history, validate, addTags, deleteTags, transaction, operation, getPage, patch)) {
+		if (!verifyMethodHasZeroOrOneOperationAnnotation(theMethod, read, search, conformance, create, update, delete, history, validate, addTags, deleteTags, transaction, operation, getPage, patch, graphQL)) {
 			return null;
 		}
 
@@ -355,6 +346,10 @@ public abstract class BaseMethodBinding<T> {
 			return new PageMethodBinding(theContext, theMethod);
 		}
 
+		if (graphQL != null) {
+			return new GraphQLMethodBinding(theMethod, theContext, theProvider);
+		}
+
 		Class<? extends IBaseResource> returnType;
 
 		Class<? extends IBaseResource> returnTypeFromRp = null;

hapi-fhir-server/src/main/java/ca/uhn/fhir/rest/server/method/BaseResourceReturningMethodBinding.java

@@ -170,14 +170,7 @@ public abstract class BaseResourceReturningMethodBinding extends BaseMethodBindi
 	}
 
 	public IBaseResource doInvokeServer(IRestfulServer<?> theServer, RequestDetails theRequest) {
-		// Method params
+		Object[] params = createMethodParams(theRequest);
-		Object[] params = new Object[getParameters().size()];
-		for (int i = 0; i < getParameters().size(); i++) {
-			IParameter param = getParameters().get(i);
-			if (param != null) {
-				params[i] = param.translateQueryParametersIntoServerArgument(theRequest, this);
-			}
-		}
 
 		Object resultObj = invokeServer(theServer, theRequest, params);
 

hapi-fhir-server/src/main/java/ca/uhn/fhir/rest/server/method/GraphQLMethodBinding.java

@@ -0,0 +1,60 @@
+package ca.uhn.fhir.rest.server.method;
+
+import ca.uhn.fhir.context.FhirContext;
+import ca.uhn.fhir.rest.api.Constants;
+import ca.uhn.fhir.rest.api.RestOperationTypeEnum;
+import ca.uhn.fhir.rest.api.server.IRestfulServer;
+import ca.uhn.fhir.rest.api.server.RequestDetails;
+import ca.uhn.fhir.rest.server.RestfulServer;
+import ca.uhn.fhir.rest.server.RestfulServerUtils;
+import ca.uhn.fhir.rest.server.exceptions.BaseServerResponseException;
+
+import java.io.IOException;
+import java.io.Writer;
+import java.lang.reflect.Method;
+
+public class GraphQLMethodBinding extends BaseMethodBinding<String> {
+
+	public GraphQLMethodBinding(Method theMethod, FhirContext theContext, Object theProvider) {
+		super(theMethod, theContext, theProvider);
+	}
+
+	@Override
+	public String getResourceName() {
+		return null;
+	}
+
+	@Override
+	public RestOperationTypeEnum getRestOperationType() {
+		return RestOperationTypeEnum.GRAPHQL_REQUEST;
+	}
+
+	@Override
+	public boolean incomingServerRequestMatchesMethod(RequestDetails theRequest) {
+		if ("graphql".equals(theRequest.getOperation())) {
+			return true;
+		}
+
+		return false;
+	}
+
+	@Override
+	public Object invokeServer(IRestfulServer<?> theServer, RequestDetails theRequest) throws BaseServerResponseException, IOException {
+		Object[] methodParams = createMethodParams(theRequest);
+		Object response = invokeServerMethod(theServer, theRequest, methodParams);
+
+		int statusCode = Constants.STATUS_HTTP_200_OK;
+		String statusMessage = Constants.HTTP_STATUS_NAMES.get(statusCode);
+		String contentType = Constants.CT_JSON;
+		String charset = Constants.CHARSET_NAME_UTF8;
+		boolean respondGzip = theRequest.isRespondGzip();
+
+		Writer writer = theRequest.getResponse().getResponseWriter(statusCode, statusMessage, contentType, charset, respondGzip);
+
+		String responseString = (String) response;
+		writer.write(responseString);
+		writer.close();
+
+		return null;
+	}
+}

hapi-fhir-server/src/main/java/ca/uhn/fhir/rest/server/method/GraphQLQueryParameter.java

@@ -0,0 +1,64 @@
+package ca.uhn.fhir.rest.server.method;
+
+/*
+ * #%L
+ * HAPI FHIR - Core Library
+ * %%
+ * Copyright (C) 2014 - 2017 University Health Network
+ * %%
+ * Licensed 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.
+ * #L%
+ */
+
+import ca.uhn.fhir.context.ConfigurationException;
+import ca.uhn.fhir.model.primitive.IntegerDt;
+import ca.uhn.fhir.parser.DataFormatException;
+import ca.uhn.fhir.rest.annotation.Count;
+import ca.uhn.fhir.rest.api.Constants;
+import ca.uhn.fhir.rest.api.server.RequestDetails;
+import ca.uhn.fhir.rest.param.ParameterUtil;
+import ca.uhn.fhir.rest.server.exceptions.InternalErrorException;
+import ca.uhn.fhir.rest.server.exceptions.InvalidRequestException;
+import org.apache.commons.lang3.StringUtils;
+
+import java.lang.reflect.Method;
+import java.util.Collection;
+
+public class GraphQLQueryParameter implements IParameter {
+
+	private Class<?> myType;
+
+	@Override
+	public Object translateQueryParametersIntoServerArgument(RequestDetails theRequest, BaseMethodBinding<?> theMethodBinding) throws InternalErrorException, InvalidRequestException {
+		String[] queryParams = theRequest.getParameters().get(Constants.PARAM_GRAPHQL_QUERY);
+		String retVal = null;
+		if (queryParams != null) {
+			if (queryParams.length > 0) {
+				retVal = queryParams[0];
+			}
+		}
+		return retVal;
+	}
+
+	@Override
+	public void initializeTypes(Method theMethod, Class<? extends Collection<?>> theOuterCollectionType, Class<? extends Collection<?>> theInnerCollectionType, Class<?> theParameterType) {
+		if (theOuterCollectionType != null) {
+			throw new ConfigurationException("Method '" + theMethod.getName() + "' in type '" +theMethod.getDeclaringClass().getCanonicalName()+ "' is annotated with @" + Count.class.getName() + " but can not be of collection type");
+		}
+		if (!String.class.equals(theParameterType)) {
+			throw new ConfigurationException("Method '" + theMethod.getName() + "' in type '" +theMethod.getDeclaringClass().getCanonicalName()+ "' is annotated with @" + Count.class.getName() + " but type '" + theParameterType + "' is an invalid type, must be one of Integer or IntegerType");
+		}
+		myType = theParameterType;
+	}
+
+}

hapi-fhir-server/src/main/java/ca/uhn/fhir/rest/server/method/MethodUtil.java

@@ -163,6 +163,8 @@ public class MethodUtil {
 						((AtParameter) param).setType(theContext, parameterType, innerCollectionType, outerCollectionType);
 					} else if (nextAnnotation instanceof Count) {
 						param = new CountParameter();
+					} else if (nextAnnotation instanceof GraphQLQuery) {
+						param = new GraphQLQueryParameter();
 					} else if (nextAnnotation instanceof Sort) {
 						param = new SortParameter(theContext);
 					} else if (nextAnnotation instanceof TransactionParam) {

hapi-fhir-structures-r4/src/main/java/org/hl7/fhir/r4/hapi/ctx/FhirServerR4.java

@@ -1,11 +1,10 @@
 package org.hl7.fhir.r4.hapi.ctx;
 
-import org.hl7.fhir.r4.hapi.rest.server.ServerCapabilityStatementProvider;
-import org.hl7.fhir.r4.hapi.rest.server.ServerProfileProvider;
-
 import ca.uhn.fhir.rest.api.server.IFhirVersionServer;
 import ca.uhn.fhir.rest.server.IResourceProvider;
 import ca.uhn.fhir.rest.server.RestfulServer;
+import org.hl7.fhir.r4.hapi.rest.server.ServerCapabilityStatementProvider;
+import org.hl7.fhir.r4.hapi.rest.server.ServerProfileProvider;
 
 public class FhirServerR4 implements IFhirVersionServer {
   @Override

hapi-fhir-structures-r4/src/test/java/ca/uhn/fhir/rest/server/GraphQLR4ProviderTest.java

@@ -0,0 +1,126 @@
+package ca.uhn.fhir.rest.server;
+
+import ca.uhn.fhir.context.FhirContext;
+import ca.uhn.fhir.rest.annotation.OptionalParam;
+import ca.uhn.fhir.rest.annotation.Search;
+import ca.uhn.fhir.rest.api.EncodingEnum;
+import ca.uhn.fhir.rest.param.TokenAndListParam;
+import ca.uhn.fhir.util.PortUtil;
+import ca.uhn.fhir.util.TestUtil;
+import org.apache.commons.io.IOUtils;
+import org.apache.http.client.methods.CloseableHttpResponse;
+import org.apache.http.client.methods.HttpGet;
+import org.apache.http.impl.client.CloseableHttpClient;
+import org.apache.http.impl.client.HttpClientBuilder;
+import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;
+import org.eclipse.jetty.server.Server;
+import org.eclipse.jetty.servlet.ServletHandler;
+import org.eclipse.jetty.servlet.ServletHolder;
+import org.hl7.fhir.instance.model.api.IBaseResource;
+import org.hl7.fhir.r4.model.HumanName;
+import org.hl7.fhir.r4.model.Patient;
+import org.junit.AfterClass;
+import org.junit.Before;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import java.nio.charset.StandardCharsets;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.TimeUnit;
+
+import static org.junit.Assert.assertEquals;
+
+public class GraphQLR4ProviderTest {
+
+	private static CloseableHttpClient ourClient;
+	private static FhirContext ourCtx = FhirContext.forR4();
+	private static TokenAndListParam ourIdentifiers;
+	private static String ourLastMethod;
+	private static final org.slf4j.Logger ourLog = org.slf4j.LoggerFactory.getLogger(GraphQLR4ProviderTest.class);
+	private static int ourPort;
+	private static Server ourServer;
+
+	@Before
+	public void before() {
+		ourLastMethod = null;
+		ourIdentifiers = null;
+	}
+
+	@Test
+	public void testSearchNormal() throws Exception {
+		HttpGet httpGet = new HttpGet("http://localhost:" + ourPort + "/Patient?identifier=foo%7Cbar");
+		CloseableHttpResponse status = ourClient.execute(httpGet);
+		try {
+			String responseContent = IOUtils.toString(status.getEntity().getContent(), StandardCharsets.UTF_8);
+			ourLog.info(responseContent);
+			assertEquals(200, status.getStatusLine().getStatusCode());
+
+			assertEquals("search", ourLastMethod);
+
+			assertEquals("foo", ourIdentifiers.getValuesAsQueryTokens().get(0).getValuesAsQueryTokens().get(0).getSystem());
+			assertEquals("bar", ourIdentifiers.getValuesAsQueryTokens().get(0).getValuesAsQueryTokens().get(0).getValue());
+		} finally {
+			IOUtils.closeQuietly(status.getEntity().getContent());
+		}
+
+	}
+
+	@AfterClass
+	public static void afterClassClearContext() throws Exception {
+		ourServer.stop();
+		TestUtil.clearAllStaticFieldsForUnitTest();
+	}
+
+	@BeforeClass
+	public static void beforeClass() throws Exception {
+		ourPort = PortUtil.findFreePort();
+		ourServer = new Server(ourPort);
+
+		DummyPatientResourceProvider patientProvider = new DummyPatientResourceProvider();
+
+		ServletHandler proxyHandler = new ServletHandler();
+		RestfulServer servlet = new RestfulServer(ourCtx);
+		servlet.setDefaultResponseEncoding(EncodingEnum.JSON);
+		servlet.setPagingProvider(new FifoMemoryPagingProvider(10));
+
+		servlet.setResourceProviders(patientProvider);
+		ServletHolder servletHolder = new ServletHolder(servlet);
+		proxyHandler.addServletWithMapping(servletHolder, "/*");
+		ourServer.setHandler(proxyHandler);
+		ourServer.start();
+
+		PoolingHttpClientConnectionManager connectionManager = new PoolingHttpClientConnectionManager(5000, TimeUnit.MILLISECONDS);
+		HttpClientBuilder builder = HttpClientBuilder.create();
+		builder.setConnectionManager(connectionManager);
+		ourClient = builder.build();
+
+	}
+
+	public static class DummyPatientResourceProvider implements IResourceProvider {
+
+		@Override
+		public Class<? extends IBaseResource> getResourceType() {
+			return Patient.class;
+		}
+
+		@SuppressWarnings("rawtypes")
+		@Search()
+		public List search(
+			@OptionalParam(name = Patient.SP_IDENTIFIER) TokenAndListParam theIdentifiers) {
+			ourLastMethod = "search";
+			ourIdentifiers = theIdentifiers;
+			ArrayList<Patient> retVal = new ArrayList<Patient>();
+			
+			for (int i = 0; i < 200; i++) {
+				Patient patient = new Patient();
+				patient.addName(new HumanName().setFamily("FAMILY"));
+				patient.getIdElement().setValue("Patient/" + i);
+				retVal.add((Patient) patient);
+			}
+			return retVal;
+		}
+
+	}
+
+}

hapi-fhir-structures-r4/src/test/java/ca/uhn/fhir/rest/server/GraphQLR4RawTest.java

@@ -0,0 +1,124 @@
+package ca.uhn.fhir.rest.server;
+
+import ca.uhn.fhir.context.FhirContext;
+import ca.uhn.fhir.rest.annotation.*;
+import ca.uhn.fhir.rest.api.Constants;
+import ca.uhn.fhir.rest.api.EncodingEnum;
+import ca.uhn.fhir.rest.param.TokenAndListParam;
+import ca.uhn.fhir.util.PortUtil;
+import ca.uhn.fhir.util.TestUtil;
+import ca.uhn.fhir.util.UrlUtil;
+import org.apache.commons.io.IOUtils;
+import org.apache.http.client.methods.CloseableHttpResponse;
+import org.apache.http.client.methods.HttpGet;
+import org.apache.http.impl.client.CloseableHttpClient;
+import org.apache.http.impl.client.HttpClientBuilder;
+import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;
+import org.eclipse.jetty.server.Server;
+import org.eclipse.jetty.servlet.ServletHandler;
+import org.eclipse.jetty.servlet.ServletHolder;
+import org.hl7.fhir.instance.model.api.IBaseResource;
+import org.hl7.fhir.r4.model.HumanName;
+import org.hl7.fhir.r4.model.IdType;
+import org.hl7.fhir.r4.model.Patient;
+import org.junit.AfterClass;
+import org.junit.Before;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import java.nio.charset.StandardCharsets;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.TimeUnit;
+
+import static org.hamcrest.Matchers.not;
+import static org.junit.Assert.*;
+
+public class GraphQLR4RawTest {
+
+	private static final org.slf4j.Logger ourLog = org.slf4j.LoggerFactory.getLogger(GraphQLR4RawTest.class);
+	private static CloseableHttpClient ourClient;
+	private static FhirContext ourCtx = FhirContext.forR4();
+	private static int ourPort;
+	private static Server ourServer;
+	private static String ourNextRetVal;
+	private static IdType ourLastId;
+	private static String ourLastQuery;
+	private static int ourMethodCount;
+
+	@AfterClass
+	public static void afterClassClearContext() throws Exception {
+		ourServer.stop();
+		TestUtil.clearAllStaticFieldsForUnitTest();
+	}
+
+	@BeforeClass
+	public static void beforeClass() throws Exception {
+		ourPort = PortUtil.findFreePort();
+		ourServer = new Server(ourPort);
+
+		MyProvider provider = new MyProvider();
+
+		ServletHandler proxyHandler = new ServletHandler();
+		RestfulServer servlet = new RestfulServer(ourCtx);
+		servlet.setDefaultResponseEncoding(EncodingEnum.JSON);
+		servlet.setPagingProvider(new FifoMemoryPagingProvider(10));
+
+		servlet.registerProvider(provider);
+		ServletHolder servletHolder = new ServletHolder(servlet);
+		proxyHandler.addServletWithMapping(servletHolder, "/*");
+		ourServer.setHandler(proxyHandler);
+		ourServer.start();
+
+		PoolingHttpClientConnectionManager connectionManager = new PoolingHttpClientConnectionManager(5000, TimeUnit.MILLISECONDS);
+		HttpClientBuilder builder = HttpClientBuilder.create();
+		builder.setConnectionManager(connectionManager);
+		ourClient = builder.build();
+
+	}
+
+	@Before
+	public void before() {
+		ourNextRetVal = null;
+		ourLastId = null;
+		ourLastQuery = null;
+		ourMethodCount = 0;
+	}
+
+	@Test
+	public void testGraphInstance() throws Exception {
+		ourNextRetVal = "{\"foo\"}";
+
+
+		HttpGet httpGet = new HttpGet("http://localhost:" + ourPort + "/Patient/123/$graphql?query=" + UrlUtil.escape("{name{family,given}}"));
+		CloseableHttpResponse status = ourClient.execute(httpGet);
+		try {
+			String responseContent = IOUtils.toString(status.getEntity().getContent(), StandardCharsets.UTF_8);
+			ourLog.info(responseContent);
+			assertEquals(200, status.getStatusLine().getStatusCode());
+
+			assertEquals("{\"foo\"}", responseContent);
+			assertEquals("application/json", status.getFirstHeader(Constants.HEADER_CONTENT_TYPE));
+			assertEquals("Patient/123", ourLastId.getValue());
+			assertEquals("{name{family,given}}", ourLastQuery);
+
+		} finally {
+			IOUtils.closeQuietly(status.getEntity().getContent());
+		}
+
+	}
+
+	public static class MyProvider {
+
+
+		@GraphQL
+		public String process(@IdParam IdType theId, @GraphQLQuery String theQuery) {
+			ourMethodCount++;
+			ourLastId = theId;
+			ourLastQuery = theQuery;
+			return ourNextRetVal;
+		}
+
+	}
+
+}

hapi-fhir-structures-r4/src/test/java/ca/uhn/fhir/util/GraphQLEngineTest.java

@@ -0,0 +1,131 @@
+package ca.uhn.fhir.util;
+
+import ca.uhn.fhir.context.FhirContext;
+import org.hl7.fhir.exceptions.FHIRException;
+import org.hl7.fhir.r4.hapi.ctx.DefaultProfileValidationSupport;
+import org.hl7.fhir.r4.hapi.ctx.HapiWorkerContext;
+import org.hl7.fhir.r4.model.*;
+import org.hl7.fhir.r4.utils.GraphQLEngine;
+import org.hl7.fhir.utilities.graphql.EGraphEngine;
+import org.hl7.fhir.utilities.graphql.EGraphQLException;
+import org.hl7.fhir.utilities.graphql.ObjectValue;
+import org.hl7.fhir.utilities.graphql.Parser;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import org.mockito.invocation.InvocationOnMock;
+import org.mockito.stubbing.Answer;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.IOException;
+
+import static org.junit.Assert.assertEquals;
+import static org.mockito.Matchers.any;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+public class GraphQLEngineTest {
+	private static HapiWorkerContext ourWorkerCtx;
+	private static FhirContext ourCtx;
+	private org.slf4j.Logger ourLog = org.slf4j.LoggerFactory.getLogger(GraphQLEngineTest.class);
+
+	@BeforeClass
+	public static void beforeClass() {
+		ourCtx = FhirContext.forR4();
+		ourWorkerCtx = new HapiWorkerContext(ourCtx, new DefaultProfileValidationSupport());
+	}
+
+	@Test
+	public void testGraphSimple() throws EGraphQLException, EGraphEngine, IOException, FHIRException {
+
+		Observation obs = createObservation();
+
+		GraphQLEngine engine = new GraphQLEngine(ourWorkerCtx);
+		engine.setFocus(obs);
+		engine.setGraphQL(Parser.parse("{valueQuantity{value,unit}}"));
+		engine.execute();
+
+		ObjectValue output = engine.getOutput();
+		StringBuilder outputBuilder = new StringBuilder();
+		output.write(outputBuilder, 0, "\n");
+
+		String expected = "{\n" +
+			"  \"valueQuantity\":{\n" +
+			"    \"value\":123,\n" +
+			"    \"unit\":\"cm\"\n" +
+			"  }\n" +
+			"}";
+		assertEquals(expected, outputBuilder.toString());
+
+	}
+
+	private Observation createObservation() {
+		Observation obs = new Observation();
+		obs.setId("http://foo.com/Patient/PATA");
+		obs.setValue(new Quantity().setValue(123).setUnit("cm"));
+		obs.setSubject(new Reference("Patient/123"));
+		return obs;
+	}
+
+	@Test
+	public void testReferences() throws EGraphQLException, EGraphEngine, IOException, FHIRException {
+
+		String graph = " { \n" +
+			"  id\n" +
+			"  subject { \n" +
+			"   reference\n" +
+			"    resource(type : Patient) { birthDate }\n" +
+			"    resource(type : Practioner) { practitionerRole {  speciality } }\n" +
+			"  }  \n" +
+			"  code {coding {system code} }\n" +
+			" }\n" +
+			" ";
+
+		GraphQLEngine engine = new GraphQLEngine(ourWorkerCtx);
+		engine.setFocus(createObservation());
+		engine.setGraphQL(Parser.parse(graph));
+		engine.setServices(createStorageServices());
+		engine.execute();
+
+		ObjectValue output = engine.getOutput();
+		StringBuilder outputBuilder = new StringBuilder();
+		output.write(outputBuilder, 0, "\n");
+
+		String expected = "{\n" +
+			"  \"id\":\"http://foo.com/Patient/PATA\",\n" +
+			"  \"subject\":{\n" +
+			"    \"reference\":\"Patient/123\",\n" +
+			"    \"resource\":{\n" +
+			"      \"birthDate\":\"2011-02-22\"\n" +
+			"    }\n" +
+			"  }\n" +
+			"}";
+		assertEquals(expected, outputBuilder.toString());
+
+	}
+
+	private GraphQLEngine.IGraphQLStorageServices createStorageServices() throws FHIRException {
+		GraphQLEngine.IGraphQLStorageServices retVal = mock(GraphQLEngine.IGraphQLStorageServices.class);
+		when(retVal.lookup(any(Object.class), any(Resource.class), any(Reference.class))).thenAnswer(new Answer<Object>() {
+			@Override
+			public Object answer(InvocationOnMock invocation) throws Throwable {
+				Object appInfo = invocation.getArguments()[0];
+				Resource context = (Resource) invocation.getArguments()[1];
+				Reference reference = (Reference) invocation.getArguments()[2];
+				ourLog.info("AppInfo: {} / Context: {} / Reference: {}", appInfo, context.getId(), reference.getReference());
+
+				if (reference.getReference().equalsIgnoreCase("Patient/123")) {
+					Patient p = new Patient();
+					p.getBirthDateElement().setValueAsString("2011-02-22");
+					return new GraphQLEngine.IGraphQLStorageServices.ReferenceResolution(context, p);
+				}
+
+				ourLog.info("Not found!");
+				return null;
+			}
+		});
+
+		return retVal;
+	}
+
+}

hapi-fhir-utilities/src/main/java/org/hl7/fhir/utilities/graphql/ObjectValue.java

@@ -41,22 +41,36 @@ public class ObjectValue extends Value {
     return result;
   }
 
+  /**
+   * Write the output using the system default line separator (as defined in {@link System#lineSeparator}
+   * @param b The StringBuilder to populate
+   * @param indent The indent level, or <code>-1</code> for no indent
+   */
   public void write(StringBuilder b, int indent) throws EGraphQLException, EGraphEngine {
+    write(b, indent, System.lineSeparator());
+  }
+
+  /**
+   * Write the output using the system default line separator (as defined in {@link System#lineSeparator}
+   * @param b The StringBuilder to populate
+   * @param indent The indent level, or <code>-1</code> for no indent
+   * @param lineSeparator The line separator
+   */
+  public void write(StringBuilder b, Integer indent, String lineSeparator) throws EGraphQLException, EGraphEngine {
     b.append("{");
-    int ni = indent;
     String s = "";
     String se = "";
-    if ((ni > -1))
+    if ((indent > -1))
     {
-      se = "\r\n"+Utilities.padLeft("",' ', ni*2);
+      se = lineSeparator + Utilities.padLeft("",' ', indent*2);
-      ni++;
+      indent++;
-      s = "\r\n"+Utilities.padLeft("",' ', ni*2);
+      s = lineSeparator + Utilities.padLeft("",' ', indent*2);
     }
     boolean first = true;
     for (Argument a : fields) {
       if (first) first = false; else b.append(",");
       b.append(s);
-      a.write(b, ni);
+      a.write(b, indent);
     }
     b.append(se);
     b.append("}");