Refactor Context to support multiple terminology services

RELEASE_NOTES.md

@@ -16,3 +16,4 @@ major upgrade to validation - use terminology server to perform more logic, and
 * R6 release support
 * IPS tool development
 * Improved errors publishing IGs
+* Refactor Context to support multiple terminology services

org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/loaderR5/R2016MayToR5Loader.java

@@ -38,6 +38,7 @@ import java.util.UUID;
 
 import org.hl7.fhir.convertors.advisors.impl.BaseAdvisor_14_50;
 import org.hl7.fhir.convertors.factory.VersionConvertorFactory_14_50;
+import org.hl7.fhir.convertors.txClient.TerminologyClientFactory;
 import org.hl7.fhir.dstu2016may.formats.JsonParser;
 import org.hl7.fhir.dstu2016may.formats.XmlParser;
 import org.hl7.fhir.dstu2016may.model.Resource;
@@ -49,6 +50,7 @@ import org.hl7.fhir.r5.model.CanonicalResource;
 import org.hl7.fhir.r5.model.CodeSystem;
 import org.hl7.fhir.r5.model.StructureDefinition;
 import org.hl7.fhir.r5.model.StructureDefinition.StructureDefinitionKind;
+import org.hl7.fhir.r5.terminologies.client.TerminologyClientManager.ITerminologyClientFactory;
 
 public class R2016MayToR5Loader extends BaseLoaderR5 {
 
@@ -136,4 +138,9 @@ public class R2016MayToR5Loader extends BaseLoaderR5 {
     return "4.3";
   }
 
+  @Override
+  public ITerminologyClientFactory txFactory() {
+    return new TerminologyClientFactory(versionString());
+  }
+
 }

org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/loaderR5/R2ToR5Loader.java

@@ -38,6 +38,7 @@ import java.util.UUID;
 
 import org.hl7.fhir.convertors.advisors.impl.BaseAdvisor_10_50;
 import org.hl7.fhir.convertors.factory.VersionConvertorFactory_10_50;
+import org.hl7.fhir.convertors.txClient.TerminologyClientFactory;
 import org.hl7.fhir.dstu2.formats.JsonParser;
 import org.hl7.fhir.dstu2.formats.XmlParser;
 import org.hl7.fhir.dstu2.model.Resource;
@@ -50,6 +51,7 @@ import org.hl7.fhir.r5.model.CanonicalResource;
 import org.hl7.fhir.r5.model.CodeSystem;
 import org.hl7.fhir.r5.model.StructureDefinition;
 import org.hl7.fhir.r5.model.StructureDefinition.StructureDefinitionKind;
+import org.hl7.fhir.r5.terminologies.client.TerminologyClientManager.ITerminologyClientFactory;
 
 public class R2ToR5Loader extends BaseLoaderR5 implements IContextResourceLoader {
 
@@ -140,4 +142,9 @@ public class R2ToR5Loader extends BaseLoaderR5 implements IContextResourceLoader
     return "1.0";
   }
 
+  @Override
+  public ITerminologyClientFactory txFactory() {
+    return new TerminologyClientFactory(versionString());
+  }
+
 }

org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/loaderR5/R3ToR5Loader.java

@@ -38,6 +38,7 @@ import java.util.UUID;
 
 import org.hl7.fhir.convertors.advisors.impl.BaseAdvisor_30_50;
 import org.hl7.fhir.convertors.factory.VersionConvertorFactory_30_50;
+import org.hl7.fhir.convertors.txClient.TerminologyClientFactory;
 import org.hl7.fhir.dstu3.formats.JsonParser;
 import org.hl7.fhir.dstu3.formats.XmlParser;
 import org.hl7.fhir.dstu3.model.Resource;
@@ -50,6 +51,7 @@ import org.hl7.fhir.r5.model.CanonicalResource;
 import org.hl7.fhir.r5.model.CodeSystem;
 import org.hl7.fhir.r5.model.StructureDefinition;
 import org.hl7.fhir.r5.model.StructureDefinition.StructureDefinitionKind;
+import org.hl7.fhir.r5.terminologies.client.TerminologyClientManager.ITerminologyClientFactory;
 
 public class R3ToR5Loader extends BaseLoaderR5 implements IContextResourceLoader {
 
@@ -135,4 +137,9 @@ public class R3ToR5Loader extends BaseLoaderR5 implements IContextResourceLoader
     return "3.0";
   }
 
+  @Override
+  public ITerminologyClientFactory txFactory() {
+    return new TerminologyClientFactory(versionString());
+  }
+
 }

org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/loaderR5/R4BToR5Loader.java

@@ -38,6 +38,7 @@ import java.util.UUID;
 
 import org.hl7.fhir.convertors.advisors.impl.BaseAdvisor_40_50;
 import org.hl7.fhir.convertors.factory.VersionConvertorFactory_40_50;
+import org.hl7.fhir.convertors.txClient.TerminologyClientFactory;
 import org.hl7.fhir.exceptions.FHIRException;
 import org.hl7.fhir.r4.formats.JsonParser;
 import org.hl7.fhir.r4.formats.XmlParser;
@@ -51,6 +52,7 @@ import org.hl7.fhir.r5.model.CanonicalResource;
 import org.hl7.fhir.r5.model.CodeSystem;
 import org.hl7.fhir.r5.model.StructureDefinition;
 import org.hl7.fhir.r5.model.StructureDefinition.StructureDefinitionKind;
+import org.hl7.fhir.r5.terminologies.client.TerminologyClientManager.ITerminologyClientFactory;
 import org.hl7.fhir.utilities.VersionUtilities;
 
 public class R4BToR5Loader extends BaseLoaderR5 implements IContextResourceLoader {
@@ -143,4 +145,9 @@ public class R4BToR5Loader extends BaseLoaderR5 implements IContextResourceLoade
   }
 
 
+  @Override
+  public ITerminologyClientFactory txFactory() {
+    return new TerminologyClientFactory(versionString());
+  }
+
 }

org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/loaderR5/R4ToR5Loader.java

@@ -38,6 +38,7 @@ import java.util.UUID;
 
 import org.hl7.fhir.convertors.advisors.impl.BaseAdvisor_40_50;
 import org.hl7.fhir.convertors.factory.VersionConvertorFactory_40_50;
+import org.hl7.fhir.convertors.txClient.TerminologyClientFactory;
 import org.hl7.fhir.exceptions.FHIRException;
 import org.hl7.fhir.r4.formats.JsonParser;
 import org.hl7.fhir.r4.formats.XmlParser;
@@ -51,6 +52,7 @@ import org.hl7.fhir.r5.model.CanonicalResource;
 import org.hl7.fhir.r5.model.CodeSystem;
 import org.hl7.fhir.r5.model.StructureDefinition;
 import org.hl7.fhir.r5.model.StructureDefinition.StructureDefinitionKind;
+import org.hl7.fhir.r5.terminologies.client.TerminologyClientManager.ITerminologyClientFactory;
 import org.hl7.fhir.utilities.VersionUtilities;
 
 public class R4ToR5Loader extends BaseLoaderR5 implements IContextResourceLoader {
@@ -144,4 +146,9 @@ public class R4ToR5Loader extends BaseLoaderR5 implements IContextResourceLoader
   }
 
 
+  @Override
+  public ITerminologyClientFactory txFactory() {
+    return new TerminologyClientFactory(versionString());
+  }
+
 }

org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/loaderR5/R5ToR5Loader.java

@@ -6,6 +6,8 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.UUID;
 
+import org.hl7.fhir.convertors.txClient.TerminologyClientFactory;
+
 /*
   Copyright (c) 2011+, HL7, Inc.
   All rights reserved.
@@ -47,6 +49,7 @@ import org.hl7.fhir.r5.model.CodeSystem;
 import org.hl7.fhir.r5.model.Resource;
 import org.hl7.fhir.r5.model.StructureDefinition;
 import org.hl7.fhir.r5.model.StructureDefinition.StructureDefinitionKind;
+import org.hl7.fhir.r5.terminologies.client.TerminologyClientManager.ITerminologyClientFactory;
 
 public class R5ToR5Loader extends BaseLoaderR5 {
 
@@ -128,4 +131,9 @@ public class R5ToR5Loader extends BaseLoaderR5 {
   }
 
 
+  @Override
+  public ITerminologyClientFactory txFactory() {
+    return new TerminologyClientFactory(versionString());
+  }
+
 }

org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/loaderR5/R6ToR5Loader.java

@@ -6,6 +6,8 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.UUID;
 
+import org.hl7.fhir.convertors.txClient.TerminologyClientFactory;
+
 /*
   Copyright (c) 2011+, HL7, Inc.
   All rights reserved.
@@ -47,6 +49,7 @@ import org.hl7.fhir.r5.model.CodeSystem;
 import org.hl7.fhir.r5.model.Resource;
 import org.hl7.fhir.r5.model.StructureDefinition;
 import org.hl7.fhir.r5.model.StructureDefinition.StructureDefinitionKind;
+import org.hl7.fhir.r5.terminologies.client.TerminologyClientManager.ITerminologyClientFactory;
 
 public class R6ToR5Loader extends BaseLoaderR5 {
 
@@ -120,5 +123,10 @@ public class R6ToR5Loader extends BaseLoaderR5 {
     return "5.0";
   }
 
+  @Override
+  public ITerminologyClientFactory txFactory() {
+    return new TerminologyClientFactory(versionString());
+  }
+
 
 }

org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/txClient/TerminologyClientFactory.java

@@ -3,36 +3,27 @@ package org.hl7.fhir.convertors.txClient;
 import java.net.URISyntaxException;
 
 import org.hl7.fhir.r5.terminologies.client.ITerminologyClient;
+import org.hl7.fhir.r5.terminologies.client.TerminologyClientManager.ITerminologyClientFactory;
+import org.hl7.fhir.r5.terminologies.client.TerminologyClientR5;
 import org.hl7.fhir.utilities.FhirPublication;
 import org.hl7.fhir.utilities.Utilities;
 import org.hl7.fhir.utilities.VersionUtilities;
 
-public class TerminologyClientFactory {
+public class TerminologyClientFactory implements ITerminologyClientFactory {
 
-  public static ITerminologyClient makeClient(String id, String url, String userAgent, FhirPublication v) throws URISyntaxException {
+  private String v;  
-    if (v == null)
+
-      return new TerminologyClientR5(id, checkEndsWith("/r4", url), userAgent);
+  public TerminologyClientFactory(FhirPublication v) {
-    switch (v) {
+    super();
-      case DSTU2016May:
+    this.v = v == null ? null : v.toCode();
-        return new TerminologyClientR3(id, checkEndsWith("/r3", url), userAgent); // r3 is the least worst match
+  }
-      case DSTU1:
+  
-        throw new Error("The version " + v + " is not currently supported");
+  public TerminologyClientFactory(String version) {
-      case DSTU2:
+    super();
-        return new TerminologyClientR2(id, checkEndsWith("/r2", url), userAgent);
+    this.v = version;
-      case R4:
-        return new TerminologyClientR4(id, checkEndsWith("/r4", url), userAgent);
-      case R4B:
-        return new TerminologyClientR4(id, checkEndsWith("/r4", url), userAgent);
-      case R5:
-        return new TerminologyClientR5(id, checkEndsWith("/r4", url), userAgent); // r4 for now, since the terminology is currently the same
-      case STU3:
-        return new TerminologyClientR3(id, checkEndsWith("/r3", url), userAgent);
-      default:
-        throw new Error("The version " + v + " is not currently supported");
-    }
   }
 
-  public static ITerminologyClient makeClient(String id, String url, String userAgent, String v) throws URISyntaxException {
+  public ITerminologyClient makeClient(String id, String url, String userAgent) throws URISyntaxException {
     if (v == null)
       return new TerminologyClientR5(id, checkEndsWith("/r4", url), userAgent);
     v = VersionUtilities.getMajMin(v);
@@ -57,7 +48,7 @@ public class TerminologyClientFactory {
     throw new Error("The version " + v + " is not currently supported");
   }
 
-  private static String checkEndsWith(String term, String url) {
+  private String checkEndsWith(String term, String url) {
     if (url.endsWith(term))
       return url;
     if (Utilities.isTxFhirOrgServer(url)) {
@@ -66,4 +57,9 @@ public class TerminologyClientFactory {
     return url;
   }
 
+  @Override
+  public String getVersion() {
+    return v;
+  }
+
 }

org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/txClient/TerminologyClientR2.java

@@ -221,4 +221,9 @@ public class TerminologyClientR2 implements ITerminologyClient {
     client.setContentLanguage(lang);
     return this;
   }
+
+  @Override
+  public int getUseCount() {
+    return client.getUseCount();
+  }
 }

org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/txClient/TerminologyClientR3.java

@@ -223,4 +223,10 @@ public class TerminologyClientR3 implements ITerminologyClient {
     client.setContentLanguage(lang);
     return this;
   }
+  
+  @Override
+  public int getUseCount() {
+    return client.getUseCount();
+  }
+
 }

org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/txClient/TerminologyClientR4.java

@@ -235,4 +235,11 @@ public class TerminologyClientR4 implements ITerminologyClient {
     client.setContentLanguage(lang);
     return this;
   }
+  
+  @Override
+  public int getUseCount() {
+    return client.getUseCount();
+  }
+
+  
 }

org.hl7.fhir.convertors/src/test/java/org/hl7/fhir/convertors/txClient/TerminologyClientFactoryTest.java

@@ -53,14 +53,14 @@ public class TerminologyClientFactoryTest {
   @ParameterizedTest
   @MethodSource("data")
   public void testMakeClient(String url, FhirPublication fhirPublication, String expectedAddress) throws URISyntaxException {
-    ITerminologyClient terminologyClient = TerminologyClientFactory.makeClient("id", url, "dummyUserAgent", fhirPublication);
+    ITerminologyClient terminologyClient = new TerminologyClientFactory(fhirPublication).makeClient("id", url, "dummyUserAgent");
     assertEquals(expectedAddress, terminologyClient.getAddress());
   }
 
   @Test
   public void testMakeClientDstu1Fails() throws URISyntaxException {
     assertThrows(Error.class, () -> {
-        ITerminologyClient terminologyClient = TerminologyClientFactory.makeClient("id", "urldoesnotmatter", "dummyUserAgent", FhirPublication.DSTU1);
+        ITerminologyClient terminologyClient = new TerminologyClientFactory(FhirPublication.DSTU1).makeClient("id", "urldoesnotmatter", "dummyUserAgent");
       }
     );
   }
@@ -68,7 +68,7 @@ public class TerminologyClientFactoryTest {
   @Test
   public void testMakeClientNullFails() throws URISyntaxException {
     assertThrows(Error.class, () -> {
-        ITerminologyClient terminologyClient = TerminologyClientFactory.makeClient("id", "urldoesnotmatter", "dummyUserAgent", FhirPublication.NULL);
+        ITerminologyClient terminologyClient = new TerminologyClientFactory(FhirPublication.NULL).makeClient("id", "urldoesnotmatter", "dummyUserAgent");
       }
     );
   }

org.hl7.fhir.dstu2/src/main/java/org/hl7/fhir/dstu2/utils/client/FHIRToolingClient.java

@@ -96,6 +96,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   private int maxResultSetSize = -1;// _count
   private Conformance conf;
   private ClientUtils utils = new ClientUtils();
+  private int useCount;
 
   // Pass enpoint for client - URI
   public FHIRToolingClient(String baseServiceUrl, String userAgent) throws URISyntaxException {
@@ -213,6 +214,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public <T extends Resource> T read(Class<T> resourceClass, String id) {// TODO Change this to AddressableResource
+    recordUse();
     ResourceRequest<T> result = null;
     try {
       result = utils.issueGetResourceRequest(resourceAddress.resolveGetUriFromResourceClassAndId(resourceClass, id),
@@ -231,6 +233,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public <T extends Resource> T vread(Class<T> resourceClass, String id, String version) {
+    recordUse();
     ResourceRequest<T> result = null;
     try {
       result = utils.issueGetResourceRequest(
@@ -254,6 +257,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   // fhir/ValueSet?url=http://hl7.org/fhir/ValueSet/clinical-findings&version=0.8
 
   public <T extends Resource> T getCanonical(Class<T> resourceClass, String canonicalURL) {
+    recordUse();
     ResourceRequest<T> result = null;
     try {
       result = utils.issueGetResourceRequest(
@@ -279,6 +283,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public Resource update(Resource resource) {
+    recordUse();
     ResourceRequest<Resource> result = null;
     try {
       List<Header> headers = null;
@@ -315,6 +320,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public <T extends Resource> T update(Class<T> resourceClass, T resource, String id) {
+    recordUse();
     ResourceRequest<T> result = null;
     try {
       List<Header> headers = null;
@@ -515,6 +521,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
 //  }
 
   public <T extends Resource> Parameters operateType(Class<T> resourceClass, String name, Parameters params) {
+    recordUse();
     boolean complex = false;
     for (ParametersParameterComponent p : params.getParameter())
       complex = complex || !(p.getValue() instanceof PrimitiveType);
@@ -548,6 +555,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public Bundle transaction(Bundle batch) {
+    recordUse();
     Bundle transactionResult = null;
     try {
       transactionResult = utils.postBatchRequest(resourceAddress.getBaseServiceUri(),
@@ -561,6 +569,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
 
   @SuppressWarnings("unchecked")
   public <T extends Resource> OperationOutcome validate(Class<T> resourceClass, T resource, String id) {
+    recordUse();
     ResourceRequest<T> result = null;
     try {
       result = utils.issuePostRequest(resourceAddress.resolveValidateUri(resourceClass, id),
@@ -705,6 +714,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public Bundle fetchFeed(String url) {
+    recordUse();
     Bundle feed = null;
     try {
       feed = utils.issueGetFeedRequest(new URI(url), getPreferredResourceFormat());
@@ -715,6 +725,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public ValueSet expandValueset(ValueSet source) {
+    recordUse();
     List<Header> headers = null;
     ResourceRequest<Resource> result = utils.issuePostRequest(
         resourceAddress.resolveOperationUri(ValueSet.class, "expand"),
@@ -734,6 +745,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public Parameters lookupCode(Map<String, String> params) {
+    recordUse();
     ResourceRequest<Resource> result = utils.issueGetResourceRequest(
         resourceAddress.resolveOperationUri(ValueSet.class, "lookup", params), getPreferredResourceFormat(),
         timeoutNormal);
@@ -751,6 +763,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public ValueSet expandValueset(ValueSet source, Parameters expParams, Map<String, String> params) {
+    recordUse();
     List<Header> headers = null;
     Parameters p = expParams == null ? new Parameters() : expParams.copy();
     p.addParameter().setName("valueSet").setResource(source);
@@ -794,6 +807,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public ConceptMap initializeClosure(String name) {
+    recordUse();
     Parameters params = new Parameters();
     params.addParameter().setName("name").setValue(new StringType(name));
     List<Header> headers = null;
@@ -815,6 +829,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public ConceptMap updateClosure(String name, Coding coding) {
+    recordUse();
     Parameters params = new Parameters();
     params.addParameter().setName("name").setValue(new StringType(name));
     params.addParameter().setName("concept").setValue(coding);
@@ -902,4 +917,11 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
     utils.setAcceptLanguage(lang);
   }
 
+  public int getUseCount() {
+    return useCount;
+  }
+
+  private void recordUse() {
+    useCount++;    
+  }
 }

org.hl7.fhir.dstu3/src/main/java/org/hl7/fhir/dstu3/utils/client/FHIRToolingClient.java

@@ -79,6 +79,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   private EnumSet<FhirPublication> allowedVersions;
   private String acceptLang;
   private String contentLang;
+  private int useCount;
 
   //Pass endpoint for client - URI
   public FHIRToolingClient(String baseServiceUrl, String userAgent) throws URISyntaxException {
@@ -187,6 +188,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public <T extends Resource> T read(Class<T> resourceClass, String id) {//TODO Change this to AddressableResource
+    recordUse();
     ResourceRequest<T> result = null;
     try {
       result = client.issueGetResourceRequest(resourceAddress.resolveGetUriFromResourceClassAndId(resourceClass, id),
@@ -204,6 +206,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public <T extends Resource> T vread(Class<T> resourceClass, String id, String version) {
+    recordUse();
     ResourceRequest<T> result = null;
     try {
       result = client.issueGetResourceRequest(resourceAddress.resolveGetUriFromResourceClassAndIdAndVersion(resourceClass, id, version),
@@ -221,6 +224,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public <T extends Resource> T getCanonical(Class<T> resourceClass, String canonicalURL) {
+    recordUse();
     ResourceRequest<T> result = null;
     try {
       result = client.issueGetResourceRequest(resourceAddress.resolveGetUriFromResourceClassAndCanonical(resourceClass, canonicalURL),
@@ -243,6 +247,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public Resource update(Resource resource) {
+    recordUse();
     org.hl7.fhir.dstu3.utils.client.network.ResourceRequest<Resource> result = null;
     try {
       result = client.issuePutRequest(resourceAddress.resolveGetUriFromResourceClassAndId(resource.getClass(), resource.getId()),
@@ -270,6 +275,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public <T extends Resource> T update(Class<T> resourceClass, T resource, String id) {
+    recordUse();
     ResourceRequest<T> result = null;
     try {
       result = client.issuePutRequest(resourceAddress.resolveGetUriFromResourceClassAndId(resourceClass, id),
@@ -297,6 +303,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public <T extends Resource> Parameters operateType(Class<T> resourceClass, String name, Parameters params) {
+    recordUse();
     boolean complex = false;
     for (ParametersParameterComponent p : params.getParameter())
       complex = complex || !(p.getValue() instanceof PrimitiveType);
@@ -339,6 +346,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
 
 
   public Bundle transaction(Bundle batch) {
+    recordUse();
     Bundle transactionResult = null;
     try {
       transactionResult = client.postBatchRequest(resourceAddress.getBaseServiceUri(), ByteUtils.resourceToByteArray(batch, false, isJson(getPreferredResourceFormat())), getPreferredResourceFormat(), "transaction", timeoutOperation + (timeoutEntry * batch.getEntry().size()));
@@ -350,6 +358,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
 
   @SuppressWarnings("unchecked")
   public <T extends Resource> OperationOutcome validate(Class<T> resourceClass, T resource, String id) {
+    recordUse();
     ResourceRequest<T> result = null;
     try {
       result = client.issuePostRequest(resourceAddress.resolveValidateUri(resourceClass, id),
@@ -395,6 +404,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public Bundle fetchFeed(String url) {
+    recordUse();
     Bundle feed = null;
     try {
       feed = client.issueGetFeedRequest(new URI(url), getPreferredResourceFormat());
@@ -405,6 +415,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public ValueSet expandValueset(ValueSet source, Parameters expParams) {
+    recordUse();
     Parameters p = expParams == null ? new Parameters() : expParams.copy();
     p.addParameter().setName("valueSet").setResource(source);
     org.hl7.fhir.dstu3.utils.client.network.ResourceRequest<Resource> result = null;
@@ -426,6 +437,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
 
 
   public Parameters lookupCode(Map<String, String> params) {
+    recordUse();
     org.hl7.fhir.dstu3.utils.client.network.ResourceRequest<Resource> result = null;
     try {
       result = client.issueGetResourceRequest(resourceAddress.resolveOperationUri(CodeSystem.class, "lookup", params),
@@ -443,6 +455,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public ValueSet expandValueset(ValueSet source, ExpansionProfile profile, Map<String, String> params) {
+    recordUse();
     Parameters p = new Parameters();
     p.addParameter().setName("valueSet").setResource(source);
     if (profile != null)
@@ -466,6 +479,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public ValueSet expandValueset(ValueSet source, Parameters expParams, Map<String, String> params) {
+    recordUse();
     Parameters p = expParams == null ? new Parameters() : expParams.copy();
     p.addParameter().setName("valueSet").setResource(source);
     for (String n : params.keySet()) {
@@ -494,6 +508,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public ConceptMap initializeClosure(String name) {
+    recordUse();
     Parameters params = new Parameters();
     params.addParameter().setName("name").setValue(new StringType(name));
     ResourceRequest<Resource> result = null;
@@ -514,6 +529,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public ConceptMap updateClosure(String name, Coding coding) {
+    recordUse();
     Parameters params = new Parameters();
     params.addParameter().setName("name").setValue(new StringType(name));
     params.addParameter().setName("concept").setValue(coding);
@@ -629,5 +645,13 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   public void setContentLanguage(String lang) {
     this.contentLang = lang;
   }
+
+  public int getUseCount() {
+    return useCount;
+  }
+
+  private void recordUse() {
+    useCount++;    
+  }
 }
 

org.hl7.fhir.r4/src/main/java/org/hl7/fhir/r4/utils/client/FHIRToolingClient.java

@@ -80,6 +80,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   private String userAgent;
   private String acceptLang;
   private String contentLang;
+  private int useCount;
 
   // Pass endpoint for client - URI
   public FHIRToolingClient(String baseServiceUrl, String userAgent) throws URISyntaxException {
@@ -162,6 +163,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public Resource read(String resourceClass, String id) {// TODO Change this to AddressableResource
+    recordUse();
     ResourceRequest<Resource> result = null;
     try {
       result = client.issueGetResourceRequest(resourceAddress.resolveGetUriFromResourceClassAndId(resourceClass, id),
@@ -178,6 +180,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public <T extends Resource> T read(Class<T> resourceClass, String id) {// TODO Change this to AddressableResource
+    recordUse();
     ResourceRequest<T> result = null;
     try {
       result = client.issueGetResourceRequest(resourceAddress.resolveGetUriFromResourceClassAndId(resourceClass, id),
@@ -194,6 +197,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public <T extends Resource> T vread(Class<T> resourceClass, String id, String version) {
+    recordUse();
     ResourceRequest<T> result = null;
     try {
       result = client.issueGetResourceRequest(
@@ -211,6 +215,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public <T extends Resource> T getCanonical(Class<T> resourceClass, String canonicalURL) {
+    recordUse();
     ResourceRequest<T> result = null;
     try {
       result = client.issueGetResourceRequest(
@@ -233,6 +238,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public Resource update(Resource resource) {
+    recordUse();
     org.hl7.fhir.r4.utils.client.network.ResourceRequest<Resource> result = null;
     try {
       result = client.issuePutRequest(
@@ -263,6 +269,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public <T extends Resource> T update(Class<T> resourceClass, T resource, String id) {
+    recordUse();
     ResourceRequest<T> result = null;
     try {
       result = client.issuePutRequest(resourceAddress.resolveGetUriFromResourceClassAndId(resourceClass, id),
@@ -292,6 +299,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public <T extends Resource> Parameters operateType(Class<T> resourceClass, String name, Parameters params) throws IOException {
+    recordUse();
     boolean complex = false;
     for (ParametersParameterComponent p : params.getParameter())
       complex = complex || !(p.getValue() instanceof PrimitiveType);
@@ -324,6 +332,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public Bundle transaction(Bundle batch) {
+    recordUse();
     Bundle transactionResult = null;
     try {
       transactionResult = client.postBatchRequest(resourceAddress.getBaseServiceUri(),
@@ -337,6 +346,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
 
   @SuppressWarnings("unchecked")
   public <T extends Resource> OperationOutcome validate(Class<T> resourceClass, T resource, String id) {
+    recordUse();
     ResourceRequest<T> result = null;
     try {
       result = client.issuePostRequest(resourceAddress.resolveValidateUri(resourceClass, id),
@@ -383,6 +393,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public Bundle fetchFeed(String url) {
+    recordUse();
     Bundle feed = null;
     try {
       feed = client.issueGetFeedRequest(new URI(url), getPreferredResourceFormat(), timeoutLong);
@@ -393,6 +404,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public ValueSet expandValueset(String vsUrl, Parameters expParams) {
+    recordUse();
     Map<String, String> parameters = new HashMap<>();
     parameters.put("url", vsUrl);
     if (expParams != null) {
@@ -422,6 +434,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public ValueSet expandValueset(ValueSet source, Parameters expParams) {
+    recordUse();
     Parameters p = expParams == null ? new Parameters() : expParams.copy();
     p.addParameter().setName("valueSet").setResource(source);
     org.hl7.fhir.r4.utils.client.network.ResourceRequest<Resource> result = null;
@@ -440,6 +453,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public Parameters lookupCode(Map<String, String> params) {
+    recordUse();
     org.hl7.fhir.r4.utils.client.network.ResourceRequest<Resource> result = null;
     try {
       result = client.issueGetResourceRequest(resourceAddress.resolveOperationUri(CodeSystem.class, "lookup", params),
@@ -455,6 +469,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public ValueSet expandValueset(ValueSet source, Parameters expParams, Map<String, String> params) {
+    recordUse();
     Parameters p = expParams == null ? new Parameters() : expParams.copy();
     p.addParameter().setName("valueSet").setResource(source);
     if (params != null) {
@@ -489,6 +504,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public ConceptMap initializeClosure(String name) {
+    recordUse();
     Parameters params = new Parameters();
     params.addParameter().setName("name").setValue(new StringType(name));
     ResourceRequest<Resource> result = null;
@@ -508,6 +524,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public ConceptMap updateClosure(String name, Coding coding) {
+    recordUse();
     Parameters params = new Parameters();
     params.addParameter().setName("name").setValue(new StringType(name));
     params.addParameter().setName("concept").setValue(coding);
@@ -619,10 +636,12 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public Bundle search(String type, String criteria) {
+    recordUse();
     return fetchFeed(Utilities.pathURL(base, type+criteria));
   }
 
   public <T extends Resource> T fetchResource(Class<T> resourceClass, String id) {
+    recordUse();
     org.hl7.fhir.r4.utils.client.network.ResourceRequest<Resource> result = null;
     try {
       result = client.issueGetResourceRequest(resourceAddress.resolveGetResource(resourceClass, id),
@@ -636,6 +655,13 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
     }
     return (T) result.getPayload();
   }
-  
+
+  public int getUseCount() {
+    return useCount;
+  }
+
+  private void recordUse() {
+    useCount++;    
+  }
 
 }

org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/context/BaseWorkerContext.java

@@ -132,6 +132,8 @@ import org.hl7.fhir.r5.terminologies.validation.VSCheckerException;
 import org.hl7.fhir.r5.terminologies.validation.ValueSetValidator;
 import org.hl7.fhir.r5.terminologies.ValueSetUtilities;
 import org.hl7.fhir.r5.terminologies.client.ITerminologyClient;
+import org.hl7.fhir.r5.terminologies.client.TerminologyClientR5.TerminologyClientR5Factory;
+import org.hl7.fhir.r5.terminologies.client.TerminologyClientManager;
 import org.hl7.fhir.r5.terminologies.client.TerminologyClientContext;
 import org.hl7.fhir.r5.utils.PackageHackerR5;
 import org.hl7.fhir.r5.utils.ResourceUtilities;
@@ -240,7 +242,7 @@ public abstract class BaseWorkerContext extends I18nBase implements IWorkerConte
   private Object lock = new Object(); // used as a lock for the data that follows
   protected String version; // although the internal resources are all R5, the version of FHIR they describe may not be 
 
-  protected TerminologyClientContext tcc = new TerminologyClientContext();
+  protected TerminologyClientManager tcc = new TerminologyClientManager(new TerminologyClientR5Factory());
   private boolean minimalMemory = false;
 
   private Map<String, Map<String, ResourceProxy>> allResourcesById = new HashMap<String, Map<String, ResourceProxy>>();
@@ -786,15 +788,15 @@ public abstract class BaseWorkerContext extends I18nBase implements IWorkerConte
         if (tcc.getTxcaps() == null) {
           try {
             logger.logMessage("Terminology server: Check for supported code systems for "+system);
-            final TerminologyCapabilities capabilityStatement = txCache.hasTerminologyCapabilities() ? txCache.getTerminologyCapabilities() : tcc.getClient().getTerminologyCapabilities();
+            final TerminologyCapabilities capabilityStatement = txCache.hasTerminologyCapabilities() ? txCache.getTerminologyCapabilities() : tcc.getMasterClient().getTerminologyCapabilities();
             txCache.cacheTerminologyCapabilities(capabilityStatement);
             setTxCaps(capabilityStatement);
           } catch (Exception e) {
             if (canRunWithoutTerminology) {
               noTerminologyServer = true;
               logger.logMessage("==============!! Running without terminology server !! ==============");
-              if (tcc.getClient() != null) {
+              if (tcc.getMasterClient() != null) {
-                logger.logMessage("txServer = "+tcc.getClient().getId());
+                logger.logMessage("txServer = "+tcc.getMasterClient().getId());
                 logger.logMessage("Error = "+e.getMessage()+"");
               }
               logger.logMessage("=====================================================================");
@@ -857,7 +859,9 @@ public abstract class BaseWorkerContext extends I18nBase implements IWorkerConte
     if (res != null) {
       return res;
     }
-    Parameters p = constructParameters(vs, hierarchical);
+    Set<String> systems = findRelevantSystems(vs);
+    TerminologyClientContext tc = tcc.chooseServer(systems, true);
+    Parameters p = constructParameters(tc, vs, hierarchical);
     for (ConceptSetComponent incl : vs.getCompose().getInclude()) {
       codeSystemsUsed.add(incl.getSystem());
     }
@@ -871,13 +875,13 @@ public abstract class BaseWorkerContext extends I18nBase implements IWorkerConte
     Map<String, String> params = new HashMap<String, String>();
     params.put("_limit", Integer.toString(expandCodesLimit ));
     params.put("_incomplete", "true");
-    txLog("$expand on "+txCache.summary(vs));
+    txLog("$expand on "+txCache.summary(vs)+" on "+tc.getAddress());
-    if (addDependentResources(p, vs)) {
+    if (addDependentResources(tc, p, vs)) {
       p.addParameter().setName("cache-id").setValue(new IdType(tcc.getCacheId()));              
     }
-    
+
     try {
-      ValueSet result = tcc.getClient().expandValueset(vs, p, params);
+      ValueSet result = tc.getClient().expandValueset(vs, p, params);
       res = new ValueSetExpansionOutcome(result).setTxLink(txLog.getLastId());  
     } catch (Exception e) {
       res = new ValueSetExpansionOutcome(e.getMessage() == null ? e.getClass().getName() : e.getMessage(), TerminologyServiceErrorClass.UNKNOWN, true);
@@ -972,14 +976,18 @@ public abstract class BaseWorkerContext extends I18nBase implements IWorkerConte
     }
 
     p.addParameter().setName("cache-id").setValue(new IdType(tcc.getCacheId()));              
-    addDependentResources(p, vs);
+    Set<String> systems = findRelevantSystems(vs);
+    TerminologyClientContext tc = tcc.chooseServer(systems, true);    
+    addDependentResources(tc, p, vs);
     
     Map<String, String> params = new HashMap<String, String>();
     params.put("_limit", Integer.toString(expandCodesLimit ));
     params.put("_incomplete", "true");
-    txLog("$expand on "+txCache.summary(vs));
+    
+    txLog("$expand on "+txCache.summary(vs)+" on "+tc.getAddress());
+    
     try {
-      ValueSet result = tcc.getClient().expandValueset(vs, p, params);
+      ValueSet result = tc.getClient().expandValueset(vs, p, params);
       if (result != null) {
         if (!result.hasUrl()) {
           result.setUrl(vs.getUrl());
@@ -1052,7 +1060,7 @@ public abstract class BaseWorkerContext extends I18nBase implements IWorkerConte
         if (!t.hasResult()) {
           try {
             ValueSetValidator vsc = constructValueSetCheckerSimple(options, vs == null ? t.getVsObj() : vs);
-            vsc.setThrowToServer(options.isUseServer() && tcc.getClient() != null);
+            vsc.setThrowToServer(options.isUseServer() && tcc.hasClient());
             ValidationResult res = vsc.validateCode("Coding", t.getCoding());
             if (txCache != null) {
               txCache.cacheValidation(t.getCacheToken(), res, TerminologyCache.TRANSIENT);
@@ -1082,7 +1090,7 @@ public abstract class BaseWorkerContext extends I18nBase implements IWorkerConte
     // for those that that failed, we try to validate on the server
     Bundle batch = new Bundle();
     batch.setType(BundleType.BATCH);
-    Set<String> systems = new HashSet<>();
+    Set<String> systems = findRelevantSystems(vs);
     for (CodingValidationRequest codingValidationRequest : codes) {
       if (!codingValidationRequest.hasResult()) {
         Parameters pIn = constructParameters(options, codingValidationRequest, vs == null ? codingValidationRequest.getVsObj() : vs);
@@ -1097,16 +1105,19 @@ public abstract class BaseWorkerContext extends I18nBase implements IWorkerConte
         }
         be.setUserData("source", codingValidationRequest);
         systems.add(codingValidationRequest.getCoding().getSystem());
+        findRelevantSystems(systems, codingValidationRequest.getCoding());
       }
     }
+    
     if (batch.getEntry().size() > 0) {
-      Bundle resp = processBatch(batch, systems);      
+      TerminologyClientContext tc = tcc.chooseServer(systems, false);
+      Bundle resp = processBatch(tc, batch, systems);      
       for (int i = 0; i < batch.getEntry().size(); i++) {
         CodingValidationRequest t = (CodingValidationRequest) batch.getEntry().get(i).getUserData("source");
         BundleEntryComponent r = resp.getEntry().get(i);
 
         if (r.getResource() instanceof Parameters) {
-          t.setResult(processValidationResult((Parameters) r.getResource(), vs != null ? vs.getUrl() : t.getVsObj() != null ? t.getVsObj().getUrl() : null, tcc.getClient().getAddress()));
+          t.setResult(processValidationResult((Parameters) r.getResource(), vs != null ? vs.getUrl() : t.getVsObj() != null ? t.getVsObj().getUrl() : null, tc.getAddress()));
           if (txCache != null) {
             txCache.cacheValidation(t.getCacheToken(), t.getResult(), TerminologyCache.PERMANENT);
           }
@@ -1117,15 +1128,15 @@ public abstract class BaseWorkerContext extends I18nBase implements IWorkerConte
     }    
   }
 
-  private Bundle processBatch(Bundle batch, Set<String> systems) {
+  private Bundle processBatch(TerminologyClientContext tc, Bundle batch, Set<String> systems) {
     txLog("$batch validate for "+batch.getEntry().size()+" codes on systems "+systems.toString());
-    if (tcc.getClient() == null) {
+    if (tcc == null) {
       throw new FHIRException(formatMessage(I18nConstants.ATTEMPT_TO_USE_TERMINOLOGY_SERVER_WHEN_NO_TERMINOLOGY_SERVER_IS_AVAILABLE));
     }
     if (txLog != null) {
       txLog.clearLastId();
     }
-    Bundle resp = tcc.getClient().validateBatch(batch);
+    Bundle resp = tc.getClient().validateBatch(batch);
     if (resp == null) {
       throw new FHIRException(formatMessage(I18nConstants.TX_SERVER_NO_BATCH_RESPONSE));          
     }
@@ -1149,14 +1160,14 @@ public abstract class BaseWorkerContext extends I18nBase implements IWorkerConte
         t.setResult(txCache.getValidation(t.getCacheToken()));
       }
     }
+    ValueSet vs = fetchResource(ValueSet.class, vsUrl);
     if (options.isUseClient()) {
-      ValueSet vs = fetchResource(ValueSet.class, vsUrl);
       if (vs != null) {
         for (CodingValidationRequest t : codes) {
           if (!t.hasResult()) {
             try {
               ValueSetValidator vsc = constructValueSetCheckerSimple(options, vs);
-              vsc.setThrowToServer(options.isUseServer() && tcc.getClient() != null);
+              vsc.setThrowToServer(options.isUseServer() && tcc.hasClient());
               ValidationResult res = vsc.validateCode("Coding", t.getCoding());
               if (txCache != null) {
                 txCache.cacheValidation(t.getCacheToken(), res, TerminologyCache.TRANSIENT);
@@ -1187,7 +1198,7 @@ public abstract class BaseWorkerContext extends I18nBase implements IWorkerConte
     // for those that that failed, we try to validate on the server
     Bundle batch = new Bundle();
     batch.setType(BundleType.BATCH);
-    Set<String> systems = new HashSet<>();
+    Set<String> systems = vs != null ? findRelevantSystems(vs) : new HashSet<>();
     for (CodingValidationRequest codingValidationRequest : codes) {
       if (!codingValidationRequest.hasResult()) {
         Parameters pIn = constructParameters(options, codingValidationRequest, vsUrl);
@@ -1204,14 +1215,16 @@ public abstract class BaseWorkerContext extends I18nBase implements IWorkerConte
         systems.add(codingValidationRequest.getCoding().getSystem());
       }
     }
+    TerminologyClientContext tc = tcc.chooseServer(systems, false);
+    
     if (batch.getEntry().size() > 0) {
-      Bundle resp = processBatch(batch, systems);      
+      Bundle resp = processBatch(tc, batch, systems);      
       for (int i = 0; i < batch.getEntry().size(); i++) {
         CodingValidationRequest t = (CodingValidationRequest) batch.getEntry().get(i).getUserData("source");
         BundleEntryComponent r = resp.getEntry().get(i);
 
         if (r.getResource() instanceof Parameters) {
-          t.setResult(processValidationResult((Parameters) r.getResource(), vsUrl, tcc.getClient().getAddress()));
+          t.setResult(processValidationResult((Parameters) r.getResource(), vsUrl, tc.getAddress()));
           if (txCache != null) {
             txCache.cacheValidation(t.getCacheToken(), t.getResult(), TerminologyCache.PERMANENT);
           }
@@ -1278,7 +1291,7 @@ public abstract class BaseWorkerContext extends I18nBase implements IWorkerConte
       try {
         ValueSetValidator vsc = constructValueSetCheckerSimple(options, vs, ctxt);
         vsc.setUnknownSystems(unknownSystems);
-        vsc.setThrowToServer(options.isUseServer() && tcc.getClient() != null);
+        vsc.setThrowToServer(options.isUseServer() && tcc.hasClient());
         if (!ValueSetUtilities.isServerSide(code.getSystem())) {
           res = vsc.validateCode(path, code);
           if (txCache != null && cachingAllowed) {
@@ -1307,14 +1320,14 @@ public abstract class BaseWorkerContext extends I18nBase implements IWorkerConte
       }
     }
     
-    if (localError != null && tcc.getClient() == null) {
+    if (localError != null && !tcc.hasClient()) {
       if (unknownSystems.size() > 0) {
         return new ValidationResult(IssueSeverity.ERROR, localError, TerminologyServiceErrorClass.CODESYSTEM_UNSUPPORTED, issues).setUnknownSystems(unknownSystems);
       } else {
         return new ValidationResult(IssueSeverity.ERROR, localError, TerminologyServiceErrorClass.UNKNOWN, issues);
       }
     }
-    if (localWarning != null && tcc.getClient() == null) {
+    if (localWarning != null && !tcc.hasClient()) {
       return new ValidationResult(IssueSeverity.WARNING,formatMessage(I18nConstants.UNABLE_TO_VALIDATE_CODE_WITHOUT_USING_SERVER, localWarning), TerminologyServiceErrorClass.BLOCKED_BY_OPTIONS, issues);       
     }
     if (!options.isUseServer()) {
@@ -1333,15 +1346,19 @@ public abstract class BaseWorkerContext extends I18nBase implements IWorkerConte
     if (noTerminologyServer) {
       return new ValidationResult(IssueSeverity.ERROR,formatMessage(I18nConstants.ERROR_VALIDATING_CODE_RUNNING_WITHOUT_TERMINOLOGY_SERVICES), TerminologyServiceErrorClass.NOSERVICE, issues);
     }
+
+    Set<String> systems = findRelevantSystems(code, vs);
+    TerminologyClientContext tc = tcc.chooseServer(systems, false);
+    
     String csumm =cachingAllowed && txCache != null ? txCache.summary(code) : null;
     if (cachingAllowed && txCache != null) {
-      txLog("$validate "+csumm+(vs == null ? "" : " for "+ txCache.summary(vs)));
+      txLog("$validate "+csumm+(vs == null ? "" : " for "+ txCache.summary(vs))+" on "+tc.getAddress());
     } else {
-      txLog("$validate "+csumm+" before cache exists");
+      txLog("$validate "+csumm+" before cache exists on "+tc.getAddress());
     }
     try {
       Parameters pIn = constructParameters(options, code);
-      res = validateOnServer(vs, pIn, options);
+      res = validateOnServer(tc, vs, pIn, options);
     } catch (Exception e) {
       res = new ValidationResult(IssueSeverity.ERROR, e.getMessage() == null ? e.getClass().getName() : e.getMessage(), null).setTxLink(txLog == null ? null : txLog.getLastId()).setErrorClass(TerminologyServiceErrorClass.SERVER_ERROR);
     }
@@ -1375,12 +1392,12 @@ public abstract class BaseWorkerContext extends I18nBase implements IWorkerConte
     return new ValueSetValidator(this, new TerminologyOperationContext(this, options), options, vs, expParameters, tcc.getTxcaps());
   }
 
-  protected Parameters constructParameters(ValueSet vs, boolean hierarchical) {
+  protected Parameters constructParameters(TerminologyClientContext tcd, ValueSet vs, boolean hierarchical) {
     Parameters p = expParameters.copy();
     p.setParameter("includeDefinition", false);
     p.setParameter("excludeNested", !hierarchical);
 
-    addDependentResources(p, vs);
+    addDependentResources(tcd, p, vs);
     p.addParameter().setName("cache-id").setValue(new IdType(tcc.getCacheId()));
     return p;
   }
@@ -1477,7 +1494,7 @@ public abstract class BaseWorkerContext extends I18nBase implements IWorkerConte
       try {
         ValueSetValidator vsc = constructValueSetCheckerSimple(options, vs);
         vsc.setUnknownSystems(unknownSystems);
-        vsc.setThrowToServer(options.isUseServer() && tcc.getClient() != null);
+        vsc.setThrowToServer(options.isUseServer() && tcc.hasClient());
         res = vsc.validateCode("CodeableConcept", code);
         if (cachingAllowed) {
           txCache.cacheValidation(cacheToken, res, TerminologyCache.TRANSIENT);
@@ -1503,14 +1520,14 @@ public abstract class BaseWorkerContext extends I18nBase implements IWorkerConte
       }
     }
 
-    if (localError != null && tcc.getClient() == null) {
+    if (localError != null && !tcc.hasClient()) {
       if (unknownSystems.size() > 0) {
         return new ValidationResult(IssueSeverity.ERROR, localError, TerminologyServiceErrorClass.CODESYSTEM_UNSUPPORTED, issues).setUnknownSystems(unknownSystems);
       } else {
         return new ValidationResult(IssueSeverity.ERROR, localError, TerminologyServiceErrorClass.UNKNOWN, issues);
       }
     }
-    if (localWarning != null && tcc.getClient() == null) {
+    if (localWarning != null && !tcc.hasClient()) {
       return new ValidationResult(IssueSeverity.WARNING,formatMessage(I18nConstants.UNABLE_TO_VALIDATE_CODE_WITHOUT_USING_SERVER, localWarning), TerminologyServiceErrorClass.BLOCKED_BY_OPTIONS, issues);       
     }
     
@@ -1522,10 +1539,13 @@ public abstract class BaseWorkerContext extends I18nBase implements IWorkerConte
     if (noTerminologyServer) {
       return new ValidationResult(IssueSeverity.ERROR, "Error validating code: running without terminology services", TerminologyServiceErrorClass.NOSERVICE, null);
     }
-    txLog("$validate "+txCache.summary(code)+" for "+ txCache.summary(vs));
+    Set<String> systems = findRelevantSystems(code, vs);
+    TerminologyClientContext tc = tcc.chooseServer(systems, false);
+
+    txLog("$validate "+txCache.summary(code)+" for "+ txCache.summary(vs)+" on "+tc.getAddress());
     try {
       Parameters pIn = constructParameters(options, code);
-      res = validateOnServer(vs, pIn, options);
+      res = validateOnServer(tc, vs, pIn, options);
     } catch (Exception e) {
       res = new ValidationResult(IssueSeverity.ERROR, e.getMessage() == null ? e.getClass().getName() : e.getMessage(), null).setTxLink(txLog == null ? null : txLog.getLastId());
     }
@@ -1535,7 +1555,74 @@ public abstract class BaseWorkerContext extends I18nBase implements IWorkerConte
     return res;
   }
 
-  protected ValidationResult validateOnServer(ValueSet vs, Parameters pin, ValidationOptions options) throws FHIRException {
+  private Set<String> findRelevantSystems(ValueSet vs) {
+    Set<String> set = new HashSet<>();
+    if (vs != null) {
+      findRelevantSystems(set, vs);
+    }
+    return set;
+  }
+
+  private Set<String> findRelevantSystems(CodeableConcept code, ValueSet vs) {
+    Set<String> set = new HashSet<>();
+    if (vs != null) {
+      findRelevantSystems(set, vs);
+    }
+    for (Coding c : code.getCoding()) {      
+      findRelevantSystems(set, c);
+    }
+    return set;
+  }
+
+  private Set<String> findRelevantSystems(Coding code, ValueSet vs) {
+    Set<String> set = new HashSet<>();
+    if (vs != null) {
+      findRelevantSystems(set, vs);
+    }
+    if (code != null) {      
+      findRelevantSystems(set, code);
+    }
+    return set;
+  }
+
+  private void findRelevantSystems(Set<String> set, ValueSet vs) {
+    for (ConceptSetComponent inc : vs.getCompose().getInclude()) {
+      findRelevantSystems(set, inc);
+    }
+    for (ConceptSetComponent inc : vs.getCompose().getExclude()) {
+      findRelevantSystems(set, inc);
+    }    
+  }
+
+  private void findRelevantSystems(Set<String> set, ConceptSetComponent inc) {
+    if (inc.hasSystem()) {
+      if (inc.hasVersion()) {
+        set.add(inc.getSystem()+"|"+inc.getVersion());
+      } else {
+        set.add(inc.getSystem());
+      }
+    }
+    for (CanonicalType u : inc.getValueSet()) {
+      ValueSet vs = fetchResource(ValueSet.class, u.getValue());
+      if (vs != null) {
+        findRelevantSystems(set, vs);
+      } else {
+        set.add(TerminologyClientManager.UNRESOLVED_VALUESET);
+      }
+    }
+  }
+
+  private void findRelevantSystems(Set<String> set, Coding c) {
+    if (c.hasSystem()) {
+      if (c.hasVersion()) {
+        set.add(c.getSystem()+"|"+c.getVersion());
+      } else {
+        set.add(c.getSystem());
+      }
+    }    
+  }
+
+  protected ValidationResult validateOnServer(TerminologyClientContext tc, ValueSet vs, Parameters pin, ValidationOptions options) throws FHIRException {
 
     if (vs != null) {
       for (ConceptSetComponent inc : vs.getCompose().getInclude()) {
@@ -1546,38 +1633,38 @@ public abstract class BaseWorkerContext extends I18nBase implements IWorkerConte
       }
     }
 
-    addServerValidationParameters(vs, pin, options);
+    addServerValidationParameters(tc, vs, pin, options);
 
     if (txLog != null) {
       txLog.clearLastId();
     }
-    if (tcc.getClient() == null) {
+    if (tc == null) {
       throw new FHIRException(formatMessage(I18nConstants.ATTEMPT_TO_USE_TERMINOLOGY_SERVER_WHEN_NO_TERMINOLOGY_SERVER_IS_AVAILABLE));
     }
     Parameters pOut;
     if (vs == null) {
-      pOut = tcc.getClient().validateCS(pin);
+      pOut = tc.getClient().validateCS(pin);
     } else {
-      pOut = tcc.getClient().validateVS(pin);
+      pOut = tc.getClient().validateVS(pin);
     }
-    return processValidationResult(pOut, vs == null ? null : vs.getUrl(), tcc.getClient().getAddress());
+    return processValidationResult(pOut, vs == null ? null : vs.getUrl(), tc.getClient().getAddress());
   }
 
-  protected void addServerValidationParameters(ValueSet vs, Parameters pin, ValidationOptions options) {
+  protected void addServerValidationParameters(TerminologyClientContext tcd, ValueSet vs, Parameters pin, ValidationOptions options) {
     boolean cache = false;
     if (vs != null) {
-      if (tcc.isTxCaching() && tcc.getCacheId() != null && vs.getUrl() != null && tcc.getCached().contains(vs.getUrl()+"|"+ vs.getVersion())) {
+      if (tcc.isTxCaching() && tcc.getCacheId() != null && vs.getUrl() != null && tcd.getCached().contains(vs.getUrl()+"|"+ vs.getVersion())) {
         pin.addParameter().setName("url").setValue(new UriType(vs.getUrl()+(vs.hasVersion() ? "|"+ vs.getVersion() : "")));
       } else if (options.getVsAsUrl()){
         pin.addParameter().setName("url").setValue(new UriType(vs.getUrl()));
       } else {
         pin.addParameter().setName("valueSet").setResource(vs);
         if (vs.getUrl() != null) {
-          tcc.getCached().add(vs.getUrl()+"|"+ vs.getVersion());
+          tcd.getCached().add(vs.getUrl()+"|"+ vs.getVersion());
         }
       }
       cache = true;
-      addDependentResources(pin, vs);
+      addDependentResources(tcd, pin, vs);
     }
     pin.addParameter().setName("cache-id").setValue(new IdType(tcc.getCacheId()));
     for (ParametersParameterComponent pp : pin.getParameter()) {
@@ -1595,40 +1682,40 @@ public abstract class BaseWorkerContext extends I18nBase implements IWorkerConte
     }
   }
 
-  private boolean addDependentResources(Parameters pin, ValueSet vs) {
+  private boolean addDependentResources(TerminologyClientContext tc, Parameters pin, ValueSet vs) {
     boolean cache = false;
     for (ConceptSetComponent inc : vs.getCompose().getInclude()) {
-      cache = addDependentResources(pin, inc, vs) || cache;
+      cache = addDependentResources(tc, pin, inc, vs) || cache;
     }
     for (ConceptSetComponent inc : vs.getCompose().getExclude()) {
-      cache = addDependentResources(pin, inc, vs) || cache;
+      cache = addDependentResources(tc, pin, inc, vs) || cache;
     }
     return cache;
   }
 
-  private boolean addDependentResources(Parameters pin, ConceptSetComponent inc, Resource src) {
+  private boolean addDependentResources(TerminologyClientContext tc, Parameters pin, ConceptSetComponent inc, Resource src) {
     boolean cache = false;
     for (CanonicalType c : inc.getValueSet()) {
       ValueSet vs = fetchResource(ValueSet.class, c.getValue(), src);
       if (vs != null && !hasCanonicalResource(pin, "tx-resource", vs.getVUrl())) {
-        cache = checkAddToParams(pin, vs) || cache;
+        cache = checkAddToParams(tc, pin, vs) || cache;
-        addDependentResources(pin, vs);
+        addDependentResources(tc, pin, vs);
       }
     }
     CodeSystem cs = fetchResource(CodeSystem.class, inc.getSystem(), src);
     if (cs != null && !hasCanonicalResource(pin, "tx-resource", cs.getVUrl()) && (cs.getContent() == CodeSystemContentMode.COMPLETE || cs.getContent() == CodeSystemContentMode.FRAGMENT)) {
-      cache = checkAddToParams(pin, cs) || cache;
+      cache = checkAddToParams(tc, pin, cs) || cache;
       // todo: supplements
     }
     return cache;
   }
 
-  private boolean checkAddToParams(Parameters pin, CanonicalResource cr) {
+  private boolean checkAddToParams(TerminologyClientContext tc, Parameters pin, CanonicalResource cr) {
     boolean cache = false;
     boolean addToParams = false;
     if (tcc.usingCache()) {
-      if (!tcc.alreadyCached(cr)) {
+      if (!tc.alreadyCached(cr)) {
-        tcc.addToCache(cr);
+        tc.addToCache(cr);
         if (logger.isDebugLogging()) {
           logger.logMessage("add to cache: "+cr.getVUrl());
         }
@@ -1782,6 +1869,7 @@ public abstract class BaseWorkerContext extends I18nBase implements IWorkerConte
       Utilities.createDirectory(cachePath);
     }
     txCache = new TerminologyCache(lock, cachePath);
+    tcc.setCache(txCache);
   }
 
   public void clearTSCache(String url) throws Exception {
@@ -1814,7 +1902,7 @@ public abstract class BaseWorkerContext extends I18nBase implements IWorkerConte
 
   @Override
   public boolean isNoTerminologyServer() {
-    return noTerminologyServer || tcc.getClient() == null;
+    return noTerminologyServer || !tcc.hasClient();
   }
 
   public void setNoTerminologyServer(boolean noTerminologyServer) {
@@ -2860,6 +2948,7 @@ public abstract class BaseWorkerContext extends I18nBase implements IWorkerConte
         }
       }  
     }
+    
     codeSystems.setVersion(version);
     valueSets.setVersion(version);
     maps.setVersion(version);
@@ -2890,18 +2979,16 @@ public abstract class BaseWorkerContext extends I18nBase implements IWorkerConte
   }
   
   public int getClientRetryCount() {
-    return tcc.getClient() == null ? 0 : tcc.getClient().getRetryCount();
+    return tcc.getRetryCount();
   }
   
   public IWorkerContext setClientRetryCount(int value) {
-    if (tcc.getClient() != null) {
+    tcc.setRetryCount(value);
-      tcc.getClient().setRetryCount(value);
-    }
     return this;
   }
 
-  public ITerminologyClient getTxClient() {
+  public TerminologyClientManager getTxClientManager() {
-    return tcc.getClient();
+    return tcc;
   }
 
   public String getCacheId() {
@@ -2959,8 +3046,7 @@ public abstract class BaseWorkerContext extends I18nBase implements IWorkerConte
 
   protected void setUserAgent(String userAgent) {
     this.userAgent = userAgent;
-    if (tcc.getClient() != null)
+    tcc.setUserAgent(userAgent);
-      tcc.getClient().setUserAgent(userAgent);
   }
 
 

org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/context/IContextResourceLoader.java

@@ -8,6 +8,7 @@ import org.hl7.fhir.exceptions.FHIRException;
 import org.hl7.fhir.r5.model.Bundle;
 import org.hl7.fhir.r5.model.CodeSystem;
 import org.hl7.fhir.r5.model.Resource;
+import org.hl7.fhir.r5.terminologies.client.TerminologyClientManager.ITerminologyClientFactory;
 import org.hl7.fhir.utilities.npm.NpmPackage;
 import org.hl7.fhir.utilities.npm.NpmPackage.PackageResourceInformation;
 
@@ -89,6 +90,11 @@ public interface IContextResourceLoader {
    */
   IContextResourceLoader setLoadProfiles(boolean value);
   
+  /**
+   * @return the terminology client factory
+   */
+  ITerminologyClientFactory txFactory();
+  
   /**
    * Called during the loading process - the loader can decide which resources to load. 
    * At this point, only the .index.json is being read 

org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/context/SimpleWorkerContext.java

@@ -68,6 +68,9 @@ import org.hl7.fhir.r5.profilemodel.PEBuilder;
 import org.hl7.fhir.r5.terminologies.CodeSystemUtilities;
 import org.hl7.fhir.r5.terminologies.JurisdictionUtilities;
 import org.hl7.fhir.r5.terminologies.client.ITerminologyClient;
+import org.hl7.fhir.r5.terminologies.client.TerminologyClientManager;
+import org.hl7.fhir.r5.terminologies.client.TerminologyClientManager.ITerminologyClientFactory;
+import org.hl7.fhir.r5.terminologies.client.TerminologyClientR5;
 import org.hl7.fhir.r5.utils.validation.IResourceValidator;
 import org.hl7.fhir.r5.utils.R5Hacker;
 import org.hl7.fhir.r5.utils.XVerExtensionManager;
@@ -248,6 +251,7 @@ public class SimpleWorkerContext extends BaseWorkerContext implements IWorkerCon
     public SimpleWorkerContext fromPackage(NpmPackage pi) throws IOException, FHIRException {
       SimpleWorkerContext context = getSimpleWorkerContextInstance();
       context.setAllowLoadingDuplicates(allowLoadingDuplicates);
+      context.tcc = new TerminologyClientManager(TerminologyClientR5.factory());
       context.loadFromPackage(pi, null);
       return build(context);
     }
@@ -256,6 +260,7 @@ public class SimpleWorkerContext extends BaseWorkerContext implements IWorkerCon
       SimpleWorkerContext context = getSimpleWorkerContextInstance();
       context.setAllowLoadingDuplicates(allowLoadingDuplicates);      
       context.version = pi.getNpm().asString("version");
+      context.tcc.setFactory(loader.txFactory());
       context.loadFromPackage(pi, loader);
       context.finishLoading(genSnapshots);
       return build(context);
@@ -327,22 +332,23 @@ public class SimpleWorkerContext extends BaseWorkerContext implements IWorkerCon
       loadBytes(name, stream);
   }
 
-  public String connectToTSServer(ITerminologyClient client, String log) {
+  public String connectToTSServer(ITerminologyClientFactory factory, ITerminologyClient client, String log) {
     try {
       txLog("Connect to "+client.getAddress());
-      tcc.setClient(client);
+      tcc.setFactory(factory);
+      tcc.setMasterClient(client);
       if (log != null && (log.endsWith(".htm") || log.endsWith(".html"))) {
         txLog = new HTMLClientLogger(log);
       } else {
         txLog = new TextClientLogger(log);
       }
-      tcc.getClient().setLogger(txLog);
+      tcc.setLogger(txLog);
-      tcc.getClient().setUserAgent(userAgent);
+      tcc.setUserAgent(userAgent);
 
-      final CapabilityStatement capabilitiesStatementQuick = txCache.hasCapabilityStatement() ? txCache.getCapabilityStatement() : tcc.getClient().getCapabilitiesStatementQuick();
+      final CapabilityStatement capabilitiesStatementQuick = txCache.hasCapabilityStatement() ? txCache.getCapabilityStatement() : tcc.getMasterClient().getCapabilitiesStatementQuick();
       txCache.cacheCapabilityStatement(capabilitiesStatementQuick);
 
-      final TerminologyCapabilities capabilityStatement = txCache.hasTerminologyCapabilities() ? txCache.getTerminologyCapabilities() : tcc.getClient().getTerminologyCapabilities();
+      final TerminologyCapabilities capabilityStatement = txCache.hasTerminologyCapabilities() ? txCache.getTerminologyCapabilities() : tcc.getMasterClient().getTerminologyCapabilities();
       txCache.cacheTerminologyCapabilities(capabilityStatement);
 
       setTxCaps(capabilityStatement);
@@ -532,6 +538,9 @@ public class SimpleWorkerContext extends BaseWorkerContext implements IWorkerCon
 	      version = "5.0.0";
 	    }
 	  }
+	  if (loader != null) {
+	    tcc.setFactory(loader.txFactory());
+	  }
 	  return t;
 	}
 

org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/terminologies/client/ITerminologyClient.java

@@ -68,4 +68,5 @@ public interface ITerminologyClient {
   ITerminologyClient setAcceptLanguage(String lang);
   ITerminologyClient setContentLanguage(String lang);
   String getUserAgent();
+  int getUseCount();
 }

org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/terminologies/client/TerminologyClientContext.java

@@ -1,65 +1,70 @@
 package org.hl7.fhir.r5.terminologies.client;
 
+import java.util.HashMap;
 import java.util.HashSet;
+import java.util.Map;
 import java.util.Set;
 
 import org.hl7.fhir.r5.model.CanonicalResource;
 import org.hl7.fhir.r5.model.TerminologyCapabilities;
-import org.hl7.fhir.r5.model.ValueSet;
+import org.hl7.fhir.r5.terminologies.client.TerminologyClientContext.TerminologyClientContextUseCount;
 
 public class TerminologyClientContext {
-  private String cacheId;
+  public class TerminologyClientContextUseCount {
-  private boolean isTxCaching;
+    private int expands;
-  private int serverQueryCount = 0;
+    private int validates;
-  private final Set<String> cached = new HashSet<>();
+    public int getExpands() {
-  protected String server;
+      return expands;
+    }
+    public void setExpands(int expands) {
+      this.expands = expands;
+    }
+    public int getValidates() {
+      return validates;
+    }
+    public void setValidates(int validates) {
+      this.validates = validates;
+    }
+    
+  }
+
   private ITerminologyClient client;
+  Map<String, TerminologyClientContextUseCount> useCounts = new HashMap<>();
   private TerminologyCapabilities txcaps;
+  private final Set<String> cached = new HashSet<>();
+  private boolean master;
 
-  public String getCacheId() {
+  protected TerminologyClientContext(ITerminologyClient client, boolean master) {
-    return cacheId; 
+    super();
-  }
+    this.client = client;
-  
+    this.master = master;
-  public void setCacheId(String cacheId) {
-    this.cacheId = cacheId;
-  }
-  
-  public boolean isTxCaching() {
-    return isTxCaching;
-  }
-  
-  public void setTxCaching(boolean isTxCaching) {
-    this.isTxCaching = isTxCaching;
-  }
-  
-  public int getServerQueryCount() {
-    return serverQueryCount;
-  }
-  
-  public void setServerQueryCount(int serverQueryCount) {
-    this.serverQueryCount = serverQueryCount;
-  }
-  
-  public Set<String> getCached() {
-    return cached;
   }
 
-  public String getServer() {
+  public Map<String, TerminologyClientContextUseCount> getUseCounts() {
-    return server;
+    return useCounts;
   }
 
-  public void setServer(String server) {
+  public boolean isMaster() {
-    this.server = server;
+    return master;
   }
 
   public ITerminologyClient getClient() {
     return client;
   }
 
-  public void setClient(ITerminologyClient client) {
+  public void seeUse(String s, boolean expand) {
-    this.client = client;
+    TerminologyClientContextUseCount uc = useCounts.get(s);
+    if (uc == null) {
+      uc = new TerminologyClientContextUseCount();
+      useCounts.put(s,uc);
+    }
+    if (expand) {
+      uc.expands++;
+    } else {
+      uc.validates++;
+    }
   }
-    
+
   public TerminologyCapabilities getTxcaps() {
     return txcaps;
   }
@@ -68,18 +73,8 @@ public class TerminologyClientContext {
     this.txcaps = txcaps;
   }
 
-  public void copy(TerminologyClientContext other) {
+  public Set<String> getCached() {
-    cacheId = other.cacheId;  
+    return cached;
-    isTxCaching = other.isTxCaching;
-    cached.addAll(other.cached);
-//    tsServer = other.tsServer;
-    client = other.client;
-    txcaps = other.txcaps;
-
-  }
-
-  public boolean usingCache() {
-    return isTxCaching && cacheId != null;
   }
 
   public boolean alreadyCached(CanonicalResource cr) {
@@ -90,6 +85,12 @@ public class TerminologyClientContext {
     cached.add(cr.getVUrl());
   }
 
-  
+  public String getAddress() {
-  
+    return client.getAddress();
+  }
+
+  public int getUseCount() {
+    return getClient().getUseCount();
+  }
+
 }

org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/terminologies/client/TerminologyClientManager.java

@@ -0,0 +1,266 @@
+package org.hl7.fhir.r5.terminologies.client;
+
+import java.io.File;
+import java.io.IOException;
+import java.net.URISyntaxException;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+import org.hl7.fhir.exceptions.TerminologyServiceException;
+import org.hl7.fhir.r5.model.CanonicalResource;
+import org.hl7.fhir.r5.model.TerminologyCapabilities;
+import org.hl7.fhir.r5.model.ValueSet;
+import org.hl7.fhir.r5.terminologies.utilities.TerminologyCache;
+import org.hl7.fhir.utilities.ToolingClientLogger;
+import org.hl7.fhir.utilities.Utilities;
+import org.hl7.fhir.utilities.json.JsonException;
+import org.hl7.fhir.utilities.json.model.JsonObject;
+import org.hl7.fhir.utilities.json.parser.JsonParser;
+
+public class TerminologyClientManager {
+  public ITerminologyClientFactory getFactory() {
+    return factory;
+  }
+
+  public interface ITerminologyClientFactory {
+    ITerminologyClient makeClient(String id, String url, String userAgent) throws URISyntaxException;
+    String getVersion();
+  }
+
+  public static final String UNRESOLVED_VALUESET = "--unknown--";
+  
+  private ITerminologyClientFactory factory;
+  private String cacheId;
+  private boolean isTxCaching;
+  private List<TerminologyClientContext> serverList = new ArrayList<>(); // clients by server address
+  private Map<String, TerminologyClientContext> serverMap = new HashMap<>(); // clients by server address
+  private Map<String, String> resMap = new HashMap<>(); // client resolution list
+  private List<String> internalErrors = new ArrayList<>();
+
+  private TerminologyCache cache;
+
+  private File cacheFile;
+
+  private String monitorServiceURL;
+
+  public TerminologyClientManager(ITerminologyClientFactory factory) {
+    super();
+    this.factory = factory;
+  }
+  
+  public String getCacheId() {
+    return cacheId; 
+  }
+  
+  public void setCacheId(String cacheId) {
+    this.cacheId = cacheId;
+  }
+  
+  public boolean isTxCaching() {
+    return isTxCaching;
+  }
+  
+  public void setTxCaching(boolean isTxCaching) {
+    this.isTxCaching = isTxCaching;
+  }
+  
+  
+  public void copy(TerminologyClientManager other) {
+    cacheId = other.cacheId;  
+    isTxCaching = other.isTxCaching;
+    serverList.addAll(other.serverList);
+    serverMap.putAll(other.serverMap);
+    resMap.putAll(other.resMap);
+  }
+
+  public boolean usingCache() {
+    return isTxCaching && cacheId != null;
+  }
+
+
+  public TerminologyClientContext chooseServer(Set<String> systems, boolean expand) throws TerminologyServiceException {
+    if (serverList.isEmpty()) {
+      return null;
+    }
+    if (systems.contains(UNRESOLVED_VALUESET)) {
+      return serverList.get(0);
+    }
+    
+    Set<TerminologyClientContext> clients = new HashSet<>();
+    for (String s : systems) {
+      clients.add(findServerForSystem(s, expand));
+    }
+    if (clients.size() == 1) {
+      return clients.iterator().next();
+    } else {
+      System.out.println("systems: "+systems.toString());
+      return serverList.get(0);
+    }
+  }
+
+  private TerminologyClientContext findServerForSystem(String s, boolean expand) throws TerminologyServiceException {
+    String server = resMap.get(s);
+    if (server == null) {
+      server = decideWhichServer(s);
+      resMap.put(s, server);
+      save();
+    }
+    TerminologyClientContext client = serverMap.get(server);
+    if (client == null) {
+      try {
+        client = new TerminologyClientContext(factory.makeClient("id"+(serverList.size()+1), server, getMasterClient().getUserAgent()), false);
+      } catch (URISyntaxException e) {
+        throw new TerminologyServiceException(e);
+      }
+      serverList.add(client);
+      serverMap.put(server, client);
+    }
+    client.seeUse(s, expand);
+    return client;
+  }
+
+  private String decideWhichServer(String url) {
+    String request = Utilities.pathURL(monitorServiceURL, "resolve?fhirVersion="+factory.getVersion()+"&url="+url);
+    try {
+      JsonObject json = JsonParser.parseObjectFromUrl(request);
+      for (JsonObject item : json.getJsonObjects("authoritative")) {
+        return item.asString("url");
+      }
+      for (JsonObject item : json.getJsonObjects("candidate")) {
+        return item.asString("url");
+      }
+    } catch (Exception e) {
+      String msg = "Error resolving system "+url+": "+e.getMessage()+" ("+request+")";
+      if (!internalErrors.contains(msg)) {
+        internalErrors.add(msg);
+      }
+      e.printStackTrace();
+    }
+    return getMasterClient().getAddress();
+    
+  }
+
+  public List<TerminologyClientContext> serverList() {
+    return serverList;
+  }
+  
+  public boolean hasClient() {
+    return !serverList.isEmpty();
+  }
+
+  public int getRetryCount() {
+    return hasClient() ? getMasterClient().getRetryCount() : 0;
+  }
+
+  public void setRetryCount(int value) {
+    if (hasClient()) {
+      getMasterClient().setRetryCount(value);
+    }
+  }
+
+  public void setUserAgent(String value) {
+    if (hasClient()) {
+      getMasterClient().setUserAgent(value);
+    }
+  }
+
+  public void setLogger(ToolingClientLogger txLog) {
+    if (hasClient()) {
+      getMasterClient().setLogger(txLog);
+    }
+  }
+
+  public void setMasterClient(ITerminologyClient client) {
+    TerminologyClientContext details = new TerminologyClientContext(client, true);
+    serverList.clear();
+    serverList.add(details);
+    serverMap.put(client.getAddress(), details);  
+    monitorServiceURL = Utilities.pathURL(Utilities.getDirectoryForURL(client.getAddress()), "tx-reg");
+  }
+  
+  public TerminologyClientContext getMaster() {
+    return serverList.isEmpty() ? null : serverList.get(0);
+  }
+
+  public ITerminologyClient getMasterClient() {
+    return serverList.isEmpty() ? null : serverList.get(0).getClient();
+  }
+
+  public Map<String, TerminologyClientContext> serverMap() {
+    Map<String, TerminologyClientContext> map = new HashMap<>();
+    for (TerminologyClientContext t : serverList) {
+      map.put(t.getClient().getAddress(), t);
+    }
+    return map;
+  }
+
+  public TerminologyCapabilities getTxcaps() {
+    return hasClient() ? serverList.get(0).getTxcaps() : null;
+  }
+
+  public void setTxcaps(TerminologyCapabilities txCaps) {
+    serverList.get(0).setTxcaps(txCaps);    
+  }
+
+  public void setFactory(ITerminologyClientFactory factory) {
+    this.factory = factory;    
+  }
+
+  public void setCache(TerminologyCache cache) {
+    this.cache = cache;
+    this.cacheFile = null;
+
+    if (cache != null) {
+      try {
+        cacheFile = new File(Utilities.path(cache.getFolder(), "system-map.json"));
+        if (cacheFile.exists()) {
+          JsonObject json = JsonParser.parseObject(cacheFile);
+          for (JsonObject pair : json.getJsonObjects("systems")) {
+            resMap.put(pair.asString("system"), pair.asString("server"));
+          }
+        }
+      } catch (Exception e) {
+        e.printStackTrace();
+      }
+    }
+  }
+
+  private void save() {
+    if (cacheFile != null) {
+      JsonObject json = new JsonObject();
+      for (String s : Utilities.sorted(resMap.keySet())) {
+        JsonObject si = new JsonObject();
+        json.forceArray("systems").add(si);
+        si.add("system", s);
+        si.add("server", resMap.get(s));
+      }
+      try {
+        JsonParser.compose(json, cacheFile, true);
+      } catch (IOException e) {
+      }
+    }
+  }
+
+  public List<String> getInternalErrors() {
+    return internalErrors;
+  }
+
+  public List<TerminologyClientContext> getServerList() {
+    return serverList;
+  }
+
+  public Map<String, TerminologyClientContext> getServerMap() {
+    return serverMap;
+  }
+
+  public String getMonitorServiceURL() {
+    return monitorServiceURL;
+  }
+
+  
+  
+}

org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/terminologies/client/TerminologyClientR5.java

@@ -1,4 +1,4 @@
-package org.hl7.fhir.convertors.txClient;
+package org.hl7.fhir.r5.terminologies.client;
 
 import java.net.URISyntaxException;
 import java.util.EnumSet;
@@ -44,6 +44,8 @@ import org.hl7.fhir.r5.model.Resource;
 import org.hl7.fhir.r5.model.TerminologyCapabilities;
 import org.hl7.fhir.r5.model.ValueSet;
 import org.hl7.fhir.r5.terminologies.client.ITerminologyClient;
+import org.hl7.fhir.r5.terminologies.client.TerminologyClientManager.ITerminologyClientFactory;
+import org.hl7.fhir.r5.terminologies.client.TerminologyClientR5.TerminologyClientR5Factory;
 import org.hl7.fhir.r5.utils.client.FHIRToolingClient;
 import org.hl7.fhir.r5.utils.client.network.ClientHeaders;
 import org.hl7.fhir.utilities.FhirPublication;
@@ -52,6 +54,28 @@ import org.hl7.fhir.utilities.Utilities;
 
 public class TerminologyClientR5 implements ITerminologyClient {
 
+  public static class TerminologyClientR5Factory implements ITerminologyClientFactory {
+
+    @Override
+    public ITerminologyClient makeClient(String id, String url, String userAgent) throws URISyntaxException {
+      return new TerminologyClientR5(id, checkEndsWith("/r4", url), userAgent);
+    }
+
+    private String checkEndsWith(String term, String url) {
+      if (url.endsWith(term))
+        return url;
+      if (Utilities.isTxFhirOrgServer(url)) {
+        return Utilities.pathURL(url, term);
+      }
+      return url;
+    }
+
+    @Override
+    public String getVersion() {
+      return "5.0.0";
+    }
+  }
+
   private final FHIRToolingClient client;
   private ClientHeaders clientHeaders;
   private String id;
@@ -211,4 +235,14 @@ public class TerminologyClientR5 implements ITerminologyClient {
     client.setContentLanguage(lang);
     return this;
   }
+  
+  @Override
+  public int getUseCount() {
+    return client.getUseCount();
+  }
+
+  public static ITerminologyClientFactory factory() {
+    return new TerminologyClientR5Factory();
+  }
+
 }

org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/test/utils/TestPackageLoader.java

@@ -1,6 +1,6 @@
 package org.hl7.fhir.r5.test.utils;
 
-import java.io.IOException;
+ import java.io.IOException;
 import java.io.InputStream;
 import java.util.ArrayList;
 import java.util.List;
@@ -12,6 +12,8 @@ import org.hl7.fhir.r5.formats.XmlParser;
 import org.hl7.fhir.r5.model.Bundle;
 import org.hl7.fhir.r5.model.CodeSystem;
 import org.hl7.fhir.r5.model.Resource;
+import org.hl7.fhir.r5.terminologies.client.TerminologyClientManager.ITerminologyClientFactory;
+import org.hl7.fhir.r5.terminologies.client.TerminologyClientR5.TerminologyClientR5Factory;
 import org.hl7.fhir.utilities.npm.NpmPackage;
 import org.hl7.fhir.utilities.npm.NpmPackage.PackageResourceInformation;
 
@@ -73,4 +75,9 @@ public class TestPackageLoader implements IContextResourceLoader {
     return true;
   }
 
+  @Override
+  public ITerminologyClientFactory txFactory() {
+    return new TerminologyClientR5Factory();
+  }
+
 }

org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/utils/client/FHIRToolingClient.java

@@ -106,6 +106,9 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   private String acceptLang;
   private String contentLang;
 
+
+  private int useCount;
+
   //Pass endpoint for client - URI
   public FHIRToolingClient(String baseServiceUrl, String userAgent) throws URISyntaxException {
     preferredResourceFormat = ResourceFormat.RESOURCE_JSON;
@@ -206,6 +209,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public Resource read(String resourceClass, String id) {// TODO Change this to AddressableResource
+    recordUse();
     ResourceRequest<Resource> result = null;
     try {
       result = client.issueGetResourceRequest(resourceAddress.resolveGetUriFromResourceClassAndId(resourceClass, id),
@@ -223,6 +227,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
 
   
   public <T extends Resource> T read(Class<T> resourceClass, String id) {//TODO Change this to AddressableResource
+    recordUse();
     ResourceRequest<T> result = null;
     try {
       result = client.issueGetResourceRequest(resourceAddress.resolveGetUriFromResourceClassAndId(resourceClass, id),
@@ -240,6 +245,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public <T extends Resource> T vread(Class<T> resourceClass, String id, String version) {
+    recordUse();
     ResourceRequest<T> result = null;
     try {
       result = client.issueGetResourceRequest(resourceAddress.resolveGetUriFromResourceClassAndIdAndVersion(resourceClass, id, version),
@@ -257,6 +263,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public <T extends Resource> T getCanonical(Class<T> resourceClass, String canonicalURL) {
+    recordUse();
     ResourceRequest<T> result = null;
     try {
       result = client.issueGetResourceRequest(resourceAddress.resolveGetUriFromResourceClassAndCanonical(resourceClass, canonicalURL),
@@ -279,6 +286,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public Resource update(Resource resource) {
+    recordUse();
     org.hl7.fhir.r5.utils.client.network.ResourceRequest<Resource> result = null;
     try {
       result = client.issuePutRequest(resourceAddress.resolveGetUriFromResourceClassAndId(resource.getClass(), resource.getId()),
@@ -306,6 +314,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public <T extends Resource> T update(Class<T> resourceClass, T resource, String id) {
+    recordUse();
     ResourceRequest<T> result = null;
     try {
       result = client.issuePutRequest(resourceAddress.resolveGetUriFromResourceClassAndId(resourceClass, id),
@@ -333,6 +342,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public <T extends Resource> Parameters operateType(Class<T> resourceClass, String name, Parameters params) {
+    recordUse();
     boolean complex = false;
     for (ParametersParameterComponent p : params.getParameter())
       complex = complex || !(p.getValue() instanceof PrimitiveType);
@@ -368,6 +378,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public Bundle transaction(Bundle batch) {
+    recordUse();
     Bundle transactionResult = null;
     try {
       transactionResult = client.postBatchRequest(resourceAddress.getBaseServiceUri(), ByteUtils.resourceToByteArray(batch, false, isJson(getPreferredResourceFormat())), getPreferredResourceFormat(),
@@ -381,6 +392,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
 
   @SuppressWarnings("unchecked")
   public <T extends Resource> OperationOutcome validate(Class<T> resourceClass, T resource, String id) {
+    recordUse();
     ResourceRequest<T> result = null;
     try {
       result = client.issuePostRequest(resourceAddress.resolveValidateUri(resourceClass, id),
@@ -426,6 +438,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public Bundle fetchFeed(String url) {
+    recordUse();
     Bundle feed = null;
     try {
       feed = client.issueGetFeedRequest(new URI(url), getPreferredResourceFormat());
@@ -436,6 +449,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public ValueSet expandValueset(ValueSet source, Parameters expParams) {
+    recordUse();
     Parameters p = expParams == null ? new Parameters() : expParams.copy();
     p.addParameter().setName("valueSet").setResource(source);
     org.hl7.fhir.r5.utils.client.network.ResourceRequest<Resource> result = null;
@@ -457,6 +471,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
 
 
   public Parameters lookupCode(Map<String, String> params) {
+    recordUse();
     org.hl7.fhir.r5.utils.client.network.ResourceRequest<Resource> result = null;
     try {
       result = client.issueGetResourceRequest(resourceAddress.resolveOperationUri(CodeSystem.class, "lookup", params),
@@ -474,6 +489,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public ValueSet expandValueset(ValueSet source, Parameters expParams, Map<String, String> params) {
+    recordUse();
     Parameters p = expParams == null ? new Parameters() : expParams.copy();
     if (source != null) {
       p.addParameter().setName("valueSet").setResource(source);
@@ -507,6 +523,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public ConceptMap initializeClosure(String name) {
+    recordUse();
     Parameters params = new Parameters();
     params.addParameter().setName("name").setValue(new StringType(name));
     ResourceRequest<Resource> result = null;
@@ -527,6 +544,7 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public ConceptMap updateClosure(String name, Coding coding) {
+    recordUse();
     Parameters params = new Parameters();
     params.addParameter().setName("name").setValue(new StringType(name));
     params.addParameter().setName("concept").setValue(coding);
@@ -654,10 +672,12 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
   }
 
   public Bundle search(String type, String criteria) {
+    recordUse();
     return fetchFeed(Utilities.pathURL(base, type+criteria));
   }
   
   public <T extends Resource> T fetchResource(Class<T> resourceClass, String id) {
+    recordUse();
     org.hl7.fhir.r5.utils.client.network.ResourceRequest<Resource> result = null;
     try {
       result = client.issueGetResourceRequest(resourceAddress.resolveGetResource(resourceClass, id),
@@ -671,6 +691,14 @@ public class FHIRToolingClient extends FHIRBaseToolingClient {
     }
     return (T) result.getPayload();
   }
+
+  private void recordUse() {
+    useCount++;    
+  }
+
+  public int getUseCount() {
+    return useCount;
+  }
   
 }
 

org.hl7.fhir.r5/src/test/java/org/hl7/fhir/r5/context/BaseWorkerContextTests.java

@@ -94,7 +94,7 @@ public class BaseWorkerContextTests {
   public void testAddServerValidationParametersDisplayWarning() throws IOException {
     BaseWorkerContext baseWorkerContext = getBaseWorkerContext();
     Parameters pin = new Parameters();
-    baseWorkerContext.addServerValidationParameters(new ValueSet(), pin, new ValidationOptions(FhirPublication.fromCode(baseWorkerContext.getVersion())).setDisplayWarningMode(true));
+    baseWorkerContext.addServerValidationParameters(baseWorkerContext.getTxClientManager().getMaster(), new ValueSet(), pin, new ValidationOptions(FhirPublication.fromCode(baseWorkerContext.getVersion())).setDisplayWarningMode(true));
     assertEquals("lenient-display-validation", pin.getParameter("mode").getValue().primitiveValue());
   }
 
@@ -102,7 +102,7 @@ public class BaseWorkerContextTests {
   public void testAddServerValidationParametersVsAsUrl() throws IOException {
     BaseWorkerContext baseWorkerContext = getBaseWorkerContext();
     Parameters pin = new Parameters();
-    baseWorkerContext.addServerValidationParameters(new ValueSet().setUrl("http://dummy.org/vs"), pin, new ValidationOptions(FhirPublication.fromCode(baseWorkerContext.getVersion())).setVsAsUrl(true));
+    baseWorkerContext.addServerValidationParameters(baseWorkerContext.getTxClientManager().getMaster(), new ValueSet().setUrl("http://dummy.org/vs"), pin, new ValidationOptions(FhirPublication.fromCode(baseWorkerContext.getVersion())).setVsAsUrl(true));
     assertEquals("uri", pin.getParameter("url").getValue().fhirType());
     assertEquals("http://dummy.org/vs", pin.getParameter("url").getValue().primitiveValue());
   }
@@ -112,7 +112,7 @@ public class BaseWorkerContextTests {
     BaseWorkerContext baseWorkerContext = getBaseWorkerContext();
 
     Parameters pin = new Parameters();
-    baseWorkerContext.addServerValidationParameters(new ValueSet(), pin, new ValidationOptions(FhirPublication.fromCode(baseWorkerContext.getVersion())));
+    baseWorkerContext.addServerValidationParameters(baseWorkerContext.getTxClientManager().getMaster(), new ValueSet(), pin, new ValidationOptions(FhirPublication.fromCode(baseWorkerContext.getVersion())));
     assertNull(pin.getParameter("mode"));
   }
 }

org.hl7.fhir.r5/src/test/java/org/hl7/fhir/r5/context/SimpleWorkerContextTests.java

@@ -93,7 +93,7 @@ public class SimpleWorkerContextTests {
   public void beforeEach() {
     context.txCache = terminologyCache;
     context.expParameters = expParameters;
-    context.tcc.setClient(terminologyClient);
+    context.tcc.setMasterClient(terminologyClient);
     context.txLog = txLog;
   }
 
@@ -189,7 +189,7 @@ public class SimpleWorkerContextTests {
 
     Mockito.doReturn(cacheToken).when(terminologyCache).generateValidationToken(validationOptions, coding, valueSet, expParameters);
     Mockito.doReturn(pIn).when(context).constructParameters(validationOptions, coding);
-    Mockito.doReturn(expectedValidationResult).when(context).validateOnServer(valueSet, pIn, validationOptions);
+    Mockito.doReturn(expectedValidationResult).when(context).validateOnServer(context.getTxClientManager().getMaster(), valueSet, pIn, validationOptions);
 
     ValidationContextCarrier ctxt = mock(ValidationContextCarrier.class);
 
@@ -233,7 +233,7 @@ public class SimpleWorkerContextTests {
 
     Mockito.verify(valueSetCheckerSimple).validateCode("CodeableConcept", codeableConcept);
     Mockito.verify(terminologyCache).cacheValidation(cacheToken, expectedValidationResult, false);
-    Mockito.verify(context, times(0)).validateOnServer(any(), any(), any());
+    Mockito.verify(context, times(0)).validateOnServer(context.getTxClientManager().getMaster(), any(), any(), any());
   }
 
 
@@ -246,7 +246,7 @@ public class SimpleWorkerContextTests {
     ValidationOptions validationOptions = CacheTestUtils.validationOptions.withNoClient();
     Mockito.doReturn(pIn).when(context).constructParameters(validationOptions, codeableConcept);
 
-    Mockito.doReturn(expectedValidationResult).when(context).validateOnServer(valueSet, pIn, validationOptions);
+    Mockito.doReturn(expectedValidationResult).when(context).validateOnServer(context.getTxClientManager().getMaster(), valueSet, pIn, validationOptions);
 
     Mockito.doReturn(cacheToken).when(terminologyCache).generateValidationToken(validationOptions, codeableConcept, valueSet, expParameters);
 
@@ -256,7 +256,7 @@ public class SimpleWorkerContextTests {
 
     Mockito.verify(valueSetCheckerSimple, times(0)).validateCode("CodeableConcept", codeableConcept);
     Mockito.verify(terminologyCache).cacheValidation(cacheToken, expectedValidationResult, true);
-    Mockito.verify(context).validateOnServer(valueSet, pIn, validationOptions);
+    Mockito.verify(context).validateOnServer(context.getTxClientManager().getMaster(),valueSet, pIn, validationOptions);
   }
 
   @Test
@@ -295,7 +295,8 @@ public class SimpleWorkerContextTests {
 
     Mockito.doReturn(cacheToken).when(terminologyCache).generateExpandToken(argThat(new ValueSetMatcher(vs)),eq(true));
 
-    Mockito.doReturn(expParameters).when(context).constructParameters(argThat(new ValueSetMatcher(vs)), eq(true));
+    // #FIXME
+//    Mockito.doReturn(expParameters).when(context).constructParameters(argThat(new ValueSetMatcher(vs)), eq(true));
 
     ValueSet expectedValueSet = new ValueSet();
 
@@ -408,7 +409,7 @@ public class SimpleWorkerContextTests {
     Mockito.doReturn(terminologyCapabilities).when(terminologyCache).getTerminologyCapabilities();
     Mockito.doReturn(capabilitiesStatement).when(terminologyCache).getCapabilityStatement();
 
-    String actual = context.connectToTSServer(terminologyClient, null);
+    String actual = context.connectToTSServer(null, terminologyClient, null);
 
     assertEquals("dummyVersion", actual);
 
@@ -430,7 +431,7 @@ public class SimpleWorkerContextTests {
     Mockito.doReturn(terminologyCapabilities).when(terminologyClient).getTerminologyCapabilities();
     Mockito.doReturn(capabilitiesStatement).when(terminologyClient).getCapabilitiesStatementQuick();
 
-    String actual = context.connectToTSServer(terminologyClient, null);
+    String actual = context.connectToTSServer(null, terminologyClient, null);
 
     assertEquals("dummyVersion", actual);
 

org.hl7.fhir.utilities/src/main/java/org/hl7/fhir/utilities/Utilities.java

@@ -750,6 +750,10 @@ public class Utilities {
     return f.getParent();
   }
 
+  public static String getDirectoryForURL(String url) {
+    return url.contains("/") && url.lastIndexOf("/") > 10 ? url.substring(0, url.lastIndexOf("/")) : url;
+  }
+
   public static String appendPeriod(String s) {
     if (Utilities.noString(s))
       return s;

org.hl7.fhir.utilities/src/main/java/org/hl7/fhir/utilities/json/parser/JsonParser.java

@@ -672,7 +672,8 @@ public class JsonParser {
   private static byte[] fetch(String source) throws IOException {
     SimpleHTTPClient fetcher = new SimpleHTTPClient();
     fetcher.addHeader("Accept", "application/json, application/fhir+json");
-    HTTPResult res = fetcher.get(source+"?nocache=" + System.currentTimeMillis());
+    String murl = source.contains("?") ? source+"&nocache=" + System.currentTimeMillis() : source+"?nocache=" + System.currentTimeMillis();
+    HTTPResult res = fetcher.get(murl);
     res.checkThrowException();
     return res.getContent();
   }

org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/ValidationEngine.java

@@ -523,7 +523,8 @@ public class ValidationEngine implements IValidatorResourceFetcher, IValidationP
       return "n/a: No Terminology Server";
     } else {
       try {
-        return context.connectToTSServer(TerminologyClientFactory.makeClient("Tx-Server", url, context.getUserAgent(), version), log);
+        TerminologyClientFactory factory = new TerminologyClientFactory(version);
+        return context.connectToTSServer(factory, factory.makeClient("Tx-Server", url, context.getUserAgent()), log);
       } catch (Exception e) {
         if (context.isCanRunWithoutTerminology()) {
           return "n/a: Running without Terminology Server (error: " + e.getMessage() + ")";

org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/services/StandAloneValidatorFetcher.java

@@ -289,7 +289,7 @@ public class StandAloneValidatorFetcher implements IValidatorResourceFetcher, IV
 
   @Nonnull
   protected ITerminologyClient getTerminologyClient(String root) throws URISyntaxException {
-    return TerminologyClientFactory.makeClient("source", root, Common.getValidatorUserAgent(), context.getVersion());
+    return new TerminologyClientFactory(context.getVersion()).makeClient("source", root, Common.getValidatorUserAgent());
   }
 
   private String getRoot(String[] p, String url) {

org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/special/TxTester.java

@@ -139,7 +139,7 @@ public class TxTester {
 
   private ITerminologyClient connectToServer() throws URISyntaxException {
     System.out.println("Connect to "+server);
-    return TerminologyClientFactory.makeClient("Test-Server", server, "Tools/Java", FhirPublication.R4);  
+    return new TerminologyClientFactory(FhirPublication.R4).makeClient("Test-Server", server, "Tools/Java");  
   }
 
 

org.hl7.fhir.validation/src/test/java/org/hl7/fhir/validation/tests/ValidationEngineTests.java

@@ -32,7 +32,7 @@ public class ValidationEngineTests {
       System.out.println("TestCurrentXml: Validate patient-example.xml in Current version");
     ValidationEngine ve = TestUtilities.getValidationEngine("hl7.fhir.r4.core#4.0.1", DEF_TX, FhirPublication.R4, "4.0.1");
     CacheVerificationLogger logger = new CacheVerificationLogger();
-    ve.getContext().getTxClient().setLogger(logger);
+    ve.getContext().getTxClientManager().getMasterClient().setLogger(logger);
     OperationOutcome op = ve.validate(FhirFormat.XML, TestingUtilities.loadTestResourceStream("validator", "patient-example.xml"), null);
     int e = errors(op);
     int w = warnings(op);
@@ -55,7 +55,7 @@ public class ValidationEngineTests {
       System.out.println("TestCurrentJson: Validate patient-example.json in Current version");
     ValidationEngine ve = TestUtilities.getValidationEngine("hl7.fhir.r4.core#4.0.1", DEF_TX, FhirPublication.R4, "4.0.1");
     CacheVerificationLogger logger = new CacheVerificationLogger();
-    ve.getContext().getTxClient().setLogger(logger);
+    ve.getContext().getTxClientManager().getMasterClient().setLogger(logger);
     OperationOutcome op = ve.validate(FhirFormat.JSON, TestingUtilities.loadTestResourceStream("validator", "patient-example.json"), null);
     int e = errors(op);
     int w = warnings(op);
@@ -74,7 +74,7 @@ public class ValidationEngineTests {
       System.out.println("TestCurrentXml: Validate patient-example.xml in Current version");
     ValidationEngine ve = TestUtilities.getValidationEngine("hl7.fhir.r4b.core#4.3.0", DEF_TX, FhirPublication.R4, "4.3.0");
     CacheVerificationLogger logger = new CacheVerificationLogger();
-    ve.getContext().getTxClient().setLogger(logger);
+    ve.getContext().getTxClientManager().getMasterClient().setLogger(logger);
     OperationOutcome op = ve.validate(FhirFormat.XML, TestingUtilities.loadTestResourceStream("validator", "patient-example.xml"), null);
     int e = errors(op);
     int w = warnings(op);
@@ -97,7 +97,7 @@ public class ValidationEngineTests {
       System.out.println("TestCurrentJson: Validate patient-example.json in Current version");
     ValidationEngine ve = TestUtilities.getValidationEngine("hl7.fhir.r4b.core#4.3.0", DEF_TX, FhirPublication.R4, "4.3.0");
     CacheVerificationLogger logger = new CacheVerificationLogger();
-    ve.getContext().getTxClient().setLogger(logger);
+    ve.getContext().getTxClientManager().getMasterClient().setLogger(logger);
     OperationOutcome op = ve.validate(FhirFormat.JSON, TestingUtilities.loadTestResourceStream("validator", "patient-example.json"), null);
     int e = errors(op);
     int w = warnings(op);
@@ -126,7 +126,7 @@ public class ValidationEngineTests {
       System.out.println("Test140: Validate patient-example.xml in v1.4.0 version");
     ValidationEngine ve = TestUtilities.getValidationEngine("hl7.fhir.r2b.core#1.4.0", DEF_TX, FhirPublication.DSTU2016May, "1.4.0");
     CacheVerificationLogger logger = new CacheVerificationLogger();
-    ve.getContext().getTxClient().setLogger(logger);
+    ve.getContext().getTxClientManager().getMasterClient().setLogger(logger);
     OperationOutcome op = ve.validate(FhirFormat.XML, TestingUtilities.loadTestResourceStream("validator", "patient140.xml"), null);
     if (!TestUtilities.silent)
       for (OperationOutcomeIssueComponent iss : op.getIssue()) {
@@ -154,7 +154,7 @@ public class ValidationEngineTests {
     ValidationEngine ve = TestUtilities.getValidationEngine("hl7.fhir.r2.core#1.0.2", DEF_TX, FhirPublication.DSTU2, "1.0.2");
     ve.setNoInvariantChecks(true);
     CacheVerificationLogger logger = new CacheVerificationLogger();
-    ve.getContext().getTxClient().setLogger(logger);
+    ve.getContext().getTxClientManager().getMasterClient().setLogger(logger);
     OperationOutcome op = ve.validate(FhirFormat.XML, TestingUtilities.loadTestResourceStream("validator", "patient102.xml"), null);
     if (!TestUtilities.silent)
       for (OperationOutcomeIssueComponent iss : op.getIssue()) {
@@ -182,7 +182,7 @@ public class ValidationEngineTests {
     ValidationEngine ve = TestUtilities.getValidationEngine("hl7.fhir.r2.core#1.0.2", DEF_TX, FhirPublication.DSTU2, "1.0.2");
     ve.setNoInvariantChecks(true);
     CacheVerificationLogger logger = new CacheVerificationLogger();
-    ve.getContext().getTxClient().setLogger(logger);
+    ve.getContext().getTxClientManager().getMasterClient().setLogger(logger);
     OperationOutcome op = ve.validate(FhirFormat.JSON, TestingUtilities.loadTestResourceStream("validator", "observation102.json"), null);
     if (!TestUtilities.silent)
       for (OperationOutcomeIssueComponent iss : op.getIssue()) {
@@ -206,7 +206,7 @@ public class ValidationEngineTests {
       System.out.println("Test301: Validate observation301.xml against Core");
     ValidationEngine ve = TestUtilities.getValidationEngine("hl7.fhir.r3.core#3.0.2", DEF_TX, FhirPublication.STU3, "3.0.2");
     CacheVerificationLogger logger = new CacheVerificationLogger();
-    ve.getContext().getTxClient().setLogger(logger);
+    ve.getContext().getTxClientManager().getMasterClient().setLogger(logger);
     if (!TestUtilities.silent)
       System.out.println("  .. load USCore");
     OperationOutcome op = ve.validate(FhirFormat.XML, TestingUtilities.loadTestResourceStream("validator", "observation301.xml"), null);
@@ -228,7 +228,7 @@ public class ValidationEngineTests {
       System.out.println("Test301USCore: Validate patient300.xml against US-Core");
     ValidationEngine ve = TestUtilities.getValidationEngine("hl7.fhir.r3.core#3.0.2", DEF_TX, FhirPublication.STU3, "3.0.2");
     CacheVerificationLogger logger = new CacheVerificationLogger();
-    ve.getContext().getTxClient().setLogger(logger);
+    ve.getContext().getTxClientManager().getMasterClient().setLogger(logger);
     IgLoader igLoader = new IgLoader(ve.getPcm(), ve.getContext(), ve.getVersion(), true);
     if (!TestUtilities.silent)
       System.out.println("  .. load USCore");

org.hl7.fhir.validation/src/test/java/org/hl7/fhir/validation/tests/ValidationTests.java

@@ -199,7 +199,7 @@ public class ValidationTests implements IEvaluationContext, IValidatorResourceFe
       currentVersion = version;
     }
     vCurr = CLONE ? new ValidationEngine(currentEngine) : currentEngine;
-    vCurr.getContext().getTxClient().setLogger(logger);
+    vCurr.getContext().getTxClientManager().getMasterClient().setLogger(logger);
     igLoader = new IgLoader(vCurr.getPcm(), vCurr.getContext(), vCurr.getVersion(), true);
 
     if (content.has("close-up")) {