feat: add server streaming support for REST transport (#902)

This PR depends on googleapis/gax-java#1599

Author: vam-google

WORKSPACE

@@ -33,7 +33,7 @@ jvm_maven_import_external(
 # which in its turn, prioritizes actual generated clients runtime dependencies
 # over the generator dependencies.
 
-_gax_java_version = "2.7.1"
+_gax_java_version = "2.10.0"
 
 http_archive(
     name = "com_google_api_gax_java",

src/main/java/com/google/api/generator/gapic/composer/common/AbstractServiceCallableFactoryClassComposer.java

@@ -189,6 +189,28 @@ protected MethodDefinition createBatchingCallableMethod(Service service, TypeSto
   protected abstract MethodDefinition createOperationCallableMethod(
       Service service, TypeStore typeStore);
 
+  protected MethodDefinition createServerStreamingCallableMethod(
+      Service service, TypeStore typeStore) {
+    String methodVariantName = "ServerStreaming";
+    String requestTemplateName = "RequestT";
+    String responseTemplateName = "ResponseT";
+    List<String> methodTemplateNames = Arrays.asList(requestTemplateName, responseTemplateName);
+    return createGenericCallableMethod(
+        service,
+        typeStore,
+        /*methodTemplateNames=*/ methodTemplateNames,
+        /*returnCallableKindName=*/ methodVariantName,
+        /*returnCallableTemplateNames=*/ methodTemplateNames,
+        /*methodVariantName=*/ methodVariantName,
+        /*grpcCallSettingsTemplateObjects=*/ methodTemplateNames.stream()
+            .map(n -> (Object) n)
+            .collect(Collectors.toList()),
+        /*callSettingsVariantName=*/ methodVariantName,
+        /*callSettingsTemplateObjects=*/ methodTemplateNames.stream()
+            .map(n -> (Object) n)
+            .collect(Collectors.toList()));
+  }
+
   protected MethodDefinition createGenericCallableMethod(
       Service service,
       TypeStore typeStore,

src/main/java/com/google/api/generator/gapic/composer/grpc/GrpcServiceCallableFactoryClassComposer.java

@@ -146,28 +146,6 @@ private MethodDefinition createBidiStreamingCallableMethod(Service service, Type
             .collect(Collectors.toList()));
   }
 
-  private MethodDefinition createServerStreamingCallableMethod(
-      Service service, TypeStore typeStore) {
-    String methodVariantName = "ServerStreaming";
-    String requestTemplateName = "RequestT";
-    String responseTemplateName = "ResponseT";
-    List<String> methodTemplateNames = Arrays.asList(requestTemplateName, responseTemplateName);
-    return createGenericCallableMethod(
-        service,
-        typeStore,
-        /*methodTemplateNames=*/ methodTemplateNames,
-        /*returnCallableKindName=*/ methodVariantName,
-        /*returnCallableTemplateNames=*/ methodTemplateNames,
-        /*methodVariantName=*/ methodVariantName,
-        /*grpcCallSettingsTemplateObjects=*/ methodTemplateNames.stream()
-            .map(n -> (Object) n)
-            .collect(Collectors.toList()),
-        /*callSettingsVariantName=*/ methodVariantName,
-        /*callSettingsTemplateObjects=*/ methodTemplateNames.stream()
-            .map(n -> (Object) n)
-            .collect(Collectors.toList()));
-  }
-
   private MethodDefinition createClientStreamingCallableMethod(
       Service service, TypeStore typeStore) {
     String methodVariantName = "ClientStreaming";

src/main/java/com/google/api/generator/gapic/composer/rest/HttpJsonServiceCallableFactoryClassComposer.java

@@ -87,6 +87,14 @@ protected List<TypeNode> createClassImplements(Service service, TypeStore typeSt
                     Arrays.asList(operationType.reference(), operationsStubType.reference()))));
   }
 
+  @Override
+  protected List<MethodDefinition> createClassMethods(Service service, TypeStore typeStore) {
+    List<MethodDefinition> classMethods =
+        new ArrayList<>(super.createClassMethods(service, typeStore));
+    classMethods.addAll(Arrays.asList(createServerStreamingCallableMethod(service, typeStore)));
+    return classMethods;
+  }
+
   @Override
   protected MethodDefinition createOperationCallableMethod(Service service, TypeStore typeStore) {
     String methodVariantName = "Operation";

src/main/java/com/google/api/generator/gapic/composer/rest/HttpJsonServiceStubClassComposer.java

@@ -17,6 +17,7 @@
 import com.google.api.client.http.HttpMethods;
 import com.google.api.core.InternalApi;
 import com.google.api.gax.httpjson.ApiMethodDescriptor;
+import com.google.api.gax.httpjson.ApiMethodDescriptor.MethodType;
 import com.google.api.gax.httpjson.FieldsExtractor;
 import com.google.api.gax.httpjson.HttpJsonCallSettings;
 import com.google.api.gax.httpjson.HttpJsonLongRunningClient;
@@ -143,6 +144,7 @@ protected Statement createMethodDescriptorVariableDecl(
             .apply(expr);
 
     expr = methodMaker.apply("setHttpMethod", getHttpMethodTypeExpr(protoMethod)).apply(expr);
+    expr = methodMaker.apply("setType", getMethodTypeExpr(protoMethod)).apply(expr);
     expr =
         methodMaker.apply("setRequestFormatter", getRequestFormatterExpr(protoMethod)).apply(expr);
     expr = methodMaker.apply("setResponseParser", setResponseParserExpr(protoMethod)).apply(expr);
@@ -977,6 +979,36 @@ private List<Expr> getHttpMethodTypeExpr(Method protoMethod) {
     return Collections.singletonList(expr);
   }
 
+  private List<Expr> getMethodTypeExpr(Method protoMethod) {
+    MethodType methodType;
+    switch (protoMethod.stream()) {
+      case NONE:
+        methodType = MethodType.UNARY;
+        break;
+      case SERVER:
+        methodType = MethodType.SERVER_STREAMING;
+        break;
+      case CLIENT:
+        // Not feasible to suppor in REST
+      case BIDI:
+        // Not feasible to suppor in REST
+      default:
+        throw new UnsupportedOperationException(
+            String.format(
+                "Methods of type %s are not supported by REST transport", protoMethod.stream()));
+    }
+    EnumRefExpr expr =
+        EnumRefExpr.builder()
+            .setName(methodType.toString())
+            .setType(
+                TypeNode.withReference(
+                    ConcreteReference.builder()
+                        .setClazz(ApiMethodDescriptor.MethodType.class)
+                        .build()))
+            .build();
+    return Collections.singletonList(expr);
+  }
+
   @Override
   protected List<Expr> createOperationsStubInitExpr(
       Service service,

src/test/java/com/google/api/generator/gapic/composer/rest/goldens/HttpJsonComplianceCallableFactory.golden

@@ -11,6 +11,8 @@ import com.google.api.gax.rpc.ClientContext;
 import com.google.api.gax.rpc.OperationCallSettings;
 import com.google.api.gax.rpc.OperationCallable;
 import com.google.api.gax.rpc.PagedCallSettings;
+import com.google.api.gax.rpc.ServerStreamingCallSettings;
+import com.google.api.gax.rpc.ServerStreamingCallable;
 import com.google.api.gax.rpc.UnaryCallSettings;
 import com.google.api.gax.rpc.UnaryCallable;
 import com.google.longrunning.Operation;
@@ -74,4 +76,14 @@ public class HttpJsonComplianceCallableFactory
     return HttpJsonCallableFactory.createOperationCallable(
         callSettings, clientContext, operationsStub.longRunningClient(), initialCallable);
   }
+
+  @Override
+  public <RequestT, ResponseT>
+      ServerStreamingCallable<RequestT, ResponseT> createServerStreamingCallable(
+          HttpJsonCallSettings<RequestT, ResponseT> httpJsonCallSettings,
+          ServerStreamingCallSettings<RequestT, ResponseT> callSettings,
+          ClientContext clientContext) {
+    return HttpJsonCallableFactory.createServerStreamingCallable(
+        httpJsonCallSettings, callSettings, clientContext);
+  }
 }

src/test/java/com/google/api/generator/gapic/composer/rest/goldens/HttpJsonComplianceStub.golden

@@ -41,6 +41,7 @@ public class HttpJsonComplianceStub extends ComplianceStub {
           ApiMethodDescriptor.<RepeatRequest, RepeatResponse>newBuilder()
               .setFullMethodName("google.showcase.v1beta1.Compliance/RepeatDataBody")
               .setHttpMethod(HttpMethods.POST)
+              .setType(ApiMethodDescriptor.MethodType.UNARY)
               .setRequestFormatter(
                   ProtoMessageRequestFormatter.<RepeatRequest>newBuilder()
                       .setPath(
@@ -74,6 +75,7 @@ public class HttpJsonComplianceStub extends ComplianceStub {
           ApiMethodDescriptor.<RepeatRequest, RepeatResponse>newBuilder()
               .setFullMethodName("google.showcase.v1beta1.Compliance/RepeatDataBodyInfo")
               .setHttpMethod(HttpMethods.POST)
+              .setType(ApiMethodDescriptor.MethodType.UNARY)
               .setRequestFormatter(
                   ProtoMessageRequestFormatter.<RepeatRequest>newBuilder()
                       .setPath(
@@ -109,6 +111,7 @@ public class HttpJsonComplianceStub extends ComplianceStub {
           ApiMethodDescriptor.<RepeatRequest, RepeatResponse>newBuilder()
               .setFullMethodName("google.showcase.v1beta1.Compliance/RepeatDataQuery")
               .setHttpMethod(HttpMethods.GET)
+              .setType(ApiMethodDescriptor.MethodType.UNARY)
               .setRequestFormatter(
                   ProtoMessageRequestFormatter.<RepeatRequest>newBuilder()
                       .setPath(
@@ -144,6 +147,7 @@ public class HttpJsonComplianceStub extends ComplianceStub {
           ApiMethodDescriptor.<RepeatRequest, RepeatResponse>newBuilder()
               .setFullMethodName("google.showcase.v1beta1.Compliance/RepeatDataSimplePath")
               .setHttpMethod(HttpMethods.GET)
+              .setType(ApiMethodDescriptor.MethodType.UNARY)
               .setRequestFormatter(
                   ProtoMessageRequestFormatter.<RepeatRequest>newBuilder()
                       .setPath(
@@ -191,6 +195,7 @@ public class HttpJsonComplianceStub extends ComplianceStub {
           ApiMethodDescriptor.<RepeatRequest, RepeatResponse>newBuilder()
               .setFullMethodName("google.showcase.v1beta1.Compliance/RepeatDataPathResource")
               .setHttpMethod(HttpMethods.GET)
+              .setType(ApiMethodDescriptor.MethodType.UNARY)
               .setRequestFormatter(
                   ProtoMessageRequestFormatter.<RepeatRequest>newBuilder()
                       .setPath(
@@ -237,6 +242,7 @@ public class HttpJsonComplianceStub extends ComplianceStub {
               .setFullMethodName(
                   "google.showcase.v1beta1.Compliance/RepeatDataPathTrailingResource")
               .setHttpMethod(HttpMethods.GET)
+              .setType(ApiMethodDescriptor.MethodType.UNARY)
               .setRequestFormatter(
                   ProtoMessageRequestFormatter.<RepeatRequest>newBuilder()
                       .setPath(

test/integration/goldens/compute/com/google/cloud/compute/v1/stub/HttpJsonAddressesCallableFactory.java

@@ -26,6 +26,8 @@
 import com.google.api.gax.rpc.OperationCallSettings;
 import com.google.api.gax.rpc.OperationCallable;
 import com.google.api.gax.rpc.PagedCallSettings;
+import com.google.api.gax.rpc.ServerStreamingCallSettings;
+import com.google.api.gax.rpc.ServerStreamingCallable;
 import com.google.api.gax.rpc.UnaryCallSettings;
 import com.google.api.gax.rpc.UnaryCallable;
 import com.google.cloud.compute.v1.Operation;
@@ -89,4 +91,14 @@ OperationCallable<RequestT, ResponseT, MetadataT> createOperationCallable(
     return HttpJsonCallableFactory.createOperationCallable(
         callSettings, clientContext, operationsStub.longRunningClient(), initialCallable);
   }
+
+  @Override
+  public <RequestT, ResponseT>
+      ServerStreamingCallable<RequestT, ResponseT> createServerStreamingCallable(
+          HttpJsonCallSettings<RequestT, ResponseT> httpJsonCallSettings,
+          ServerStreamingCallSettings<RequestT, ResponseT> callSettings,
+          ClientContext clientContext) {
+    return HttpJsonCallableFactory.createServerStreamingCallable(
+        httpJsonCallSettings, callSettings, clientContext);
+  }
 }

test/integration/goldens/compute/com/google/cloud/compute/v1/stub/HttpJsonAddressesStub.java

@@ -69,6 +69,7 @@ public class HttpJsonAddressesStub extends AddressesStub {
           ApiMethodDescriptor.<AggregatedListAddressesRequest, AddressAggregatedList>newBuilder()
               .setFullMethodName("google.cloud.compute.v1.Addresses/AggregatedList")
               .setHttpMethod(HttpMethods.GET)
+              .setType(ApiMethodDescriptor.MethodType.UNARY)
               .setRequestFormatter(
                   ProtoMessageRequestFormatter.<AggregatedListAddressesRequest>newBuilder()
                       .setPath(
@@ -117,6 +118,7 @@ public class HttpJsonAddressesStub extends AddressesStub {
       ApiMethodDescriptor.<DeleteAddressRequest, Operation>newBuilder()
           .setFullMethodName("google.cloud.compute.v1.Addresses/Delete")
           .setHttpMethod(HttpMethods.DELETE)
+          .setType(ApiMethodDescriptor.MethodType.UNARY)
           .setRequestFormatter(
               ProtoMessageRequestFormatter.<DeleteAddressRequest>newBuilder()
                   .setPath(
@@ -166,6 +168,7 @@ public class HttpJsonAddressesStub extends AddressesStub {
       ApiMethodDescriptor.<InsertAddressRequest, Operation>newBuilder()
           .setFullMethodName("google.cloud.compute.v1.Addresses/Insert")
           .setHttpMethod(HttpMethods.POST)
+          .setType(ApiMethodDescriptor.MethodType.UNARY)
           .setRequestFormatter(
               ProtoMessageRequestFormatter.<InsertAddressRequest>newBuilder()
                   .setPath(
@@ -217,6 +220,7 @@ public class HttpJsonAddressesStub extends AddressesStub {
       ApiMethodDescriptor.<ListAddressesRequest, AddressList>newBuilder()
           .setFullMethodName("google.cloud.compute.v1.Addresses/List")
           .setHttpMethod(HttpMethods.GET)
+          .setType(ApiMethodDescriptor.MethodType.UNARY)
           .setRequestFormatter(
               ProtoMessageRequestFormatter.<ListAddressesRequest>newBuilder()
                   .setPath(

test/integration/goldens/compute/com/google/cloud/compute/v1/stub/HttpJsonRegionOperationsCallableFactory.java

@@ -27,6 +27,8 @@
 import com.google.api.gax.rpc.OperationCallSettings;
 import com.google.api.gax.rpc.OperationCallable;
 import com.google.api.gax.rpc.PagedCallSettings;
+import com.google.api.gax.rpc.ServerStreamingCallSettings;
+import com.google.api.gax.rpc.ServerStreamingCallable;
 import com.google.api.gax.rpc.UnaryCallSettings;
 import com.google.api.gax.rpc.UnaryCallable;
 import com.google.longrunning.Operation;
@@ -90,4 +92,14 @@ OperationCallable<RequestT, ResponseT, MetadataT> createOperationCallable(
     return HttpJsonCallableFactory.createOperationCallable(
         callSettings, clientContext, operationsStub.longRunningClient(), initialCallable);
   }
+
+  @Override
+  public <RequestT, ResponseT>
+      ServerStreamingCallable<RequestT, ResponseT> createServerStreamingCallable(
+          HttpJsonCallSettings<RequestT, ResponseT> httpJsonCallSettings,
+          ServerStreamingCallSettings<RequestT, ResponseT> callSettings,
+          ClientContext clientContext) {
+    return HttpJsonCallableFactory.createServerStreamingCallable(
+        httpJsonCallSettings, callSettings, clientContext);
+  }
 }

test/integration/goldens/compute/com/google/cloud/compute/v1/stub/HttpJsonRegionOperationsStub.java

@@ -63,6 +63,7 @@ public class HttpJsonRegionOperationsStub extends RegionOperationsStub {
           ApiMethodDescriptor.<GetRegionOperationRequest, Operation>newBuilder()
               .setFullMethodName("google.cloud.compute.v1.RegionOperations/Get")
               .setHttpMethod(HttpMethods.GET)
+              .setType(ApiMethodDescriptor.MethodType.UNARY)
               .setRequestFormatter(
                   ProtoMessageRequestFormatter.<GetRegionOperationRequest>newBuilder()
                       .setPath(
@@ -117,6 +118,7 @@ public class HttpJsonRegionOperationsStub extends RegionOperationsStub {
           ApiMethodDescriptor.<WaitRegionOperationRequest, Operation>newBuilder()
               .setFullMethodName("google.cloud.compute.v1.RegionOperations/Wait")
               .setHttpMethod(HttpMethods.POST)
+              .setType(ApiMethodDescriptor.MethodType.UNARY)
               .setRequestFormatter(
                   ProtoMessageRequestFormatter.<WaitRegionOperationRequest>newBuilder()
                       .setPath(