fix: Introduce a ClientTransportConfig interface, update ClientConfig to make use of it, and remove the http-client and grpc dependencies from the client config module

Author: fjuma

client/config/pom.xml

@@ -18,11 +18,6 @@
     <description>Java SDK for the Agent2Agent Protocol (A2A) - Client Configuration</description>
 
     <dependencies>
-        <dependency>
-            <groupId>${project.groupId}</groupId>
-            <artifactId>a2a-java-sdk-http-client</artifactId>
-            <version>${project.version}</version>
-        </dependency>
         <dependency>
             <groupId>${project.groupId}</groupId>
             <artifactId>a2a-java-sdk-spec</artifactId>
@@ -39,10 +34,6 @@
             <artifactId>mockserver-netty</artifactId>
             <scope>test</scope>
         </dependency>
-        <dependency>
-            <groupId>io.grpc</groupId>
-            <artifactId>grpc-api</artifactId>
-        </dependency>
     </dependencies>
 
 </project>

client/config/src/main/java/io/a2a/client/config/ClientConfig.java

@@ -3,9 +3,7 @@
 import java.util.List;
 import java.util.Map;
 
-import io.a2a.client.http.A2AHttpClient;
 import io.a2a.spec.PushNotificationConfig;
-import io.grpc.Channel;
 
 /**
  * Configuration for the A2A client factory.
@@ -14,23 +12,21 @@ public class ClientConfig {
 
     private final Boolean streaming;
     private final Boolean polling;
-    private final A2AHttpClient httpClient;
-    private final Channel channel;
+    private final List<ClientTransportConfig> clientTransportConfigs;
     private final List<String> supportedTransports;
     private final Boolean useClientPreference;
     private final List<String> acceptedOutputModes;
     private final PushNotificationConfig pushNotificationConfig;
     private final Integer historyLength;
     private final Map<String, Object> metadata;
 
-    public ClientConfig(Boolean streaming, Boolean polling, A2AHttpClient httpClient, Channel channel,
+    public ClientConfig(Boolean streaming, Boolean polling, List<ClientTransportConfig> clientTransportConfigs,
                         List<String> supportedTransports, Boolean useClientPreference,
                         List<String> acceptedOutputModes, PushNotificationConfig pushNotificationConfig,
                         Integer historyLength, Map<String, Object> metadata) {
         this.streaming = streaming == null ? true : streaming;
         this.polling = polling == null ? false : polling;
-        this.httpClient = httpClient;
-        this.channel = channel;
+        this.clientTransportConfigs = clientTransportConfigs;
         this.supportedTransports = supportedTransports;
         this.useClientPreference = useClientPreference == null ? false : useClientPreference;
         this.acceptedOutputModes = acceptedOutputModes;
@@ -47,12 +43,8 @@ public boolean isPolling() {
         return polling;
     }
 
-    public A2AHttpClient getHttpClient() {
-        return httpClient;
-    }
-
-    public Channel getChannel() {
-        return channel;
+    public List<ClientTransportConfig> getClientTransportConfigs() {
+        return clientTransportConfigs;
     }
 
     public List<String> getSupportedTransports() {
@@ -82,8 +74,7 @@ public Map<String, Object> getMetadata() {
     public static class Builder {
         private Boolean streaming;
         private Boolean polling;
-        private A2AHttpClient httpClient;
-        private Channel channel;
+        private List<ClientTransportConfig> clientTransportConfigs;
         private List<String> supportedTransports;
         private Boolean useClientPreference;
         private List<String> acceptedOutputModes;
@@ -101,13 +92,8 @@ public Builder setPolling(Boolean polling) {
             return this;
         }
 
-        public Builder setHttpClient(A2AHttpClient httpClient) {
-            this.httpClient = httpClient;
-            return this;
-        }
-
-        public Builder setChannel(Channel channel) {
-            this.channel = channel;
+        public Builder setClientTransportConfigs(List<ClientTransportConfig> clientTransportConfigs) {
+            this.clientTransportConfigs = clientTransportConfigs;
             return this;
         }
 
@@ -142,7 +128,7 @@ public Builder setMetadata(Map<String, Object> metadata) {
         }
 
         public ClientConfig build() {
-            return new ClientConfig(streaming, polling, httpClient, channel,
+            return new ClientConfig(streaming, polling, clientTransportConfigs,
                     supportedTransports, useClientPreference, acceptedOutputModes,
                     pushNotificationConfig, historyLength, metadata);
         }

client/config/src/main/java/io/a2a/client/config/ClientTransportConfig.java

@@ -0,0 +1,7 @@
+package io.a2a.client.config;
+
+/**
+ * Configuration for an A2A client transport.
+ */
+public interface ClientTransportConfig {
+}

client/transport/grpc/src/main/java/io/a2a/client/transport/grpc/GrpcTransportConfig.java

@@ -0,0 +1,17 @@
+package io.a2a.client.transport.grpc;
+
+import io.a2a.client.config.ClientTransportConfig;
+import io.grpc.ManagedChannelBuilder;
+
+public class GrpcTransportConfig implements ClientTransportConfig {
+
+    private final ManagedChannelBuilder<?> channelBuilder;
+
+    public GrpcTransportConfig(ManagedChannelBuilder<?> channelBuilder) {
+        this.channelBuilder = channelBuilder;
+    }
+
+    public ManagedChannelBuilder<?> getManagedChannelBuilder() {
+        return channelBuilder;
+    }
+}

client/transport/grpc/src/main/java/io/a2a/client/transport/grpc/GrpcTransportProvider.java

@@ -4,10 +4,13 @@
 
 import io.a2a.client.config.ClientCallInterceptor;
 import io.a2a.client.config.ClientConfig;
+import io.a2a.client.config.ClientTransportConfig;
 import io.a2a.client.transport.spi.ClientTransport;
 import io.a2a.client.transport.spi.ClientTransportProvider;
 import io.a2a.spec.AgentCard;
 import io.a2a.spec.TransportProtocol;
+import io.grpc.Channel;
+import io.grpc.ManagedChannelBuilder;
 
 /**
  * Provider for gRPC transport implementation.
@@ -18,7 +21,19 @@ public class GrpcTransportProvider implements ClientTransportProvider {
     public ClientTransport create(ClientConfig clientConfig, AgentCard agentCard,
                                   String agentUrl, List<ClientCallInterceptor> interceptors) {
         // not making use of the interceptors for gRPC for now
-        return new GrpcTransport(clientConfig.getChannel(), agentCard);
+        ManagedChannelBuilder<?> managedChannelBuilder = null;
+        List<ClientTransportConfig> clientTransportConfigs = clientConfig.getClientTransportConfigs();
+        if (clientTransportConfigs != null) {
+            for (ClientTransportConfig clientTransportConfig : clientTransportConfigs) {
+                if (clientTransportConfig instanceof GrpcTransportConfig grpcTransportConfig) {
+                    managedChannelBuilder = grpcTransportConfig.getManagedChannelBuilder();
+                    break;
+                }
+            }
+        }
+        Channel channel = managedChannelBuilder == null ? ManagedChannelBuilder.forTarget(agentUrl).build()
+                : managedChannelBuilder.forTarget(agentUrl).build();
+        return new GrpcTransport(channel, agentCard);
     }
 
     @Override

client/transport/jsonrpc/src/main/java/io/a2a/client/transport/jsonrpc/JSONRPCTransportConfig.java

@@ -0,0 +1,17 @@
+package io.a2a.client.transport.jsonrpc;
+
+import io.a2a.client.config.ClientTransportConfig;
+import io.a2a.client.http.A2AHttpClient;
+
+public class JSONRPCTransportConfig implements ClientTransportConfig {
+
+    private final A2AHttpClient httpClient;
+
+    public JSONRPCTransportConfig(A2AHttpClient httpClient) {
+        this.httpClient = httpClient;
+    }
+
+    public A2AHttpClient getHttpClient() {
+        return httpClient;
+    }
+}

client/transport/jsonrpc/src/main/java/io/a2a/client/transport/jsonrpc/JSONRPCTransportProvider.java

@@ -4,6 +4,8 @@
 
 import io.a2a.client.config.ClientCallInterceptor;
 import io.a2a.client.config.ClientConfig;
+import io.a2a.client.config.ClientTransportConfig;
+import io.a2a.client.http.A2AHttpClient;
 import io.a2a.client.transport.spi.ClientTransport;
 import io.a2a.client.transport.spi.ClientTransportProvider;
 import io.a2a.spec.AgentCard;
@@ -14,7 +16,17 @@ public class JSONRPCTransportProvider implements ClientTransportProvider {
     @Override
     public ClientTransport create(ClientConfig clientConfig, AgentCard agentCard,
                                   String agentUrl, List<ClientCallInterceptor> interceptors) {
-        return new JSONRPCTransport(clientConfig.getHttpClient(), agentCard, agentUrl, interceptors);
+        A2AHttpClient httpClient = null;
+        List<ClientTransportConfig> clientTransportConfigs = clientConfig.getClientTransportConfigs();
+        if (clientTransportConfigs != null) {
+            for (ClientTransportConfig clientTransportConfig : clientTransportConfigs) {
+                if (clientTransportConfig instanceof JSONRPCTransportConfig jsonrpcTransportConfig) {
+                    httpClient = jsonrpcTransportConfig.getHttpClient();
+                    break;
+                }
+            }
+        }
+        return new JSONRPCTransport(httpClient, agentCard, agentUrl, interceptors);
     }
 
     @Override