refactor: GH-165 Decoupled the transport layer

client/src/main/java/io/a2a/A2A.java

@@ -4,13 +4,13 @@
 import java.util.Map;
 
 import io.a2a.client.A2ACardResolver;
-import io.a2a.http.A2AHttpClient;
-import io.a2a.http.JdkA2AHttpClient;
 import io.a2a.spec.A2AClientError;
 import io.a2a.spec.A2AClientJSONError;
 import io.a2a.spec.AgentCard;
 import io.a2a.spec.Message;
 import io.a2a.spec.TextPart;
+import io.a2a.transport.A2ATransport;
+import io.a2a.transport.http.JdkA2AHttpTransport;
 
 
 /**
@@ -80,20 +80,20 @@ private static Message toMessage(String text, Message.Role role, String messageI
      * @throws A2AClientJSONError f the response body cannot be decoded as JSON or validated against the AgentCard schema
      */
     public static AgentCard getAgentCard(String agentUrl) throws A2AClientError, A2AClientJSONError {
-        return getAgentCard(new JdkA2AHttpClient(), agentUrl);
+        return getAgentCard(new JdkA2AHttpTransport(), agentUrl);
     }
 
     /**
      * Get the agent card for an A2A agent.
      *
-     * @param httpClient the http client to use
+     * @param transport the transport to use
      * @param agentUrl the base URL for the agent whose agent card we want to retrieve
      * @return the agent card
      * @throws A2AClientError If an HTTP error occurs fetching the card
      * @throws A2AClientJSONError f the response body cannot be decoded as JSON or validated against the AgentCard schema
      */
-    public static AgentCard getAgentCard(A2AHttpClient httpClient, String agentUrl) throws A2AClientError, A2AClientJSONError  {
-        return getAgentCard(httpClient, agentUrl, null, null);
+    public static AgentCard getAgentCard(A2ATransport transport, String agentUrl) throws A2AClientError, A2AClientJSONError  {
+        return getAgentCard(transport, agentUrl, null, null);
     }
 
     /**
@@ -108,13 +108,13 @@ public static AgentCard getAgentCard(A2AHttpClient httpClient, String agentUrl)
      * @throws A2AClientJSONError f the response body cannot be decoded as JSON or validated against the AgentCard schema
      */
     public static AgentCard getAgentCard(String agentUrl, String relativeCardPath, Map<String, String> authHeaders) throws A2AClientError, A2AClientJSONError {
-        return getAgentCard(new JdkA2AHttpClient(), agentUrl, relativeCardPath, authHeaders);
+        return getAgentCard(new JdkA2AHttpTransport(), agentUrl, relativeCardPath, authHeaders);
     }
 
     /**
      * Get the agent card for an A2A agent.
      *
-     * @param httpClient the http client to use
+     * @param transport the transport to use
      * @param agentUrl the base URL for the agent whose agent card we want to retrieve
      * @param relativeCardPath optional path to the agent card endpoint relative to the base
      *                         agent URL, defaults to ".well-known/agent.json"
@@ -123,8 +123,8 @@ public static AgentCard getAgentCard(String agentUrl, String relativeCardPath, M
      * @throws A2AClientError If an HTTP error occurs fetching the card
      * @throws A2AClientJSONError f the response body cannot be decoded as JSON or validated against the AgentCard schema
      */
-    public static AgentCard getAgentCard(A2AHttpClient httpClient, String agentUrl, String relativeCardPath, Map<String, String> authHeaders) throws A2AClientError, A2AClientJSONError  {
-        A2ACardResolver resolver = new A2ACardResolver(httpClient, agentUrl, relativeCardPath, authHeaders);
+    public static AgentCard getAgentCard(A2ATransport transport, String agentUrl, String relativeCardPath, Map<String, String> authHeaders) throws A2AClientError, A2AClientJSONError  {
+        A2ACardResolver resolver = new A2ACardResolver(transport, agentUrl, relativeCardPath, authHeaders);
         return resolver.getAgentCard();
     }
 }

client/src/main/java/io/a2a/client/A2ACardResolver.java

@@ -1,53 +1,48 @@
 package io.a2a.client;
 
-import static io.a2a.util.Utils.unmarshalFrom;
-
-import java.io.IOException;
 import java.util.Map;
 
-import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.core.type.TypeReference;
-import io.a2a.http.A2AHttpClient;
-import io.a2a.http.A2AHttpResponse;
+import io.a2a.transport.A2ATransport;
 import io.a2a.spec.A2AClientError;
 import io.a2a.spec.A2AClientJSONError;
 import io.a2a.spec.AgentCard;
 
 public class A2ACardResolver {
-    private final A2AHttpClient httpClient;
+    private final A2ATransport transport;
     private final String url;
     private final Map<String, String> authHeaders;
 
     static String DEFAULT_AGENT_CARD_PATH = "/.well-known/agent.json";
 
     static final TypeReference<AgentCard> AGENT_CARD_TYPE_REFERENCE = new TypeReference<>() {};
     /**
-     * @param httpClient the http client to use
+     * @param transport the transport to use
      * @param baseUrl the base URL for the agent whose agent card we want to retrieve
      */
-    public A2ACardResolver(A2AHttpClient httpClient, String baseUrl) {
-        this(httpClient, baseUrl, null, null);
+    public A2ACardResolver(A2ATransport transport, String baseUrl) {
+        this(transport, baseUrl, null, null);
     }
 
     /**
-     * @param httpClient the http client to use
+     * @param transport the transport to use
      * @param baseUrl the base URL for the agent whose agent card we want to retrieve
      * @param agentCardPath optional path to the agent card endpoint relative to the base
      *                         agent URL, defaults to ".well-known/agent.json"
      */
-    public A2ACardResolver(A2AHttpClient httpClient, String baseUrl, String agentCardPath) {
-        this(httpClient, baseUrl, agentCardPath, null);
+    public A2ACardResolver(A2ATransport transport, String baseUrl, String agentCardPath) {
+        this(transport, baseUrl, agentCardPath, null);
     }
 
     /**
-     * @param httpClient the http client to use
+     * @param transport the transport to use
      * @param baseUrl the base URL for the agent whose agent card we want to retrieve
      * @param agentCardPath optional path to the agent card endpoint relative to the base
      *                         agent URL, defaults to ".well-known/agent.json"
      * @param authHeaders the HTTP authentication headers to use. May be {@code null}
      */
-    public A2ACardResolver(A2AHttpClient httpClient, String baseUrl, String agentCardPath, Map<String, String> authHeaders) {
-        this.httpClient = httpClient;
+    public A2ACardResolver(A2ATransport transport, String baseUrl, String agentCardPath, Map<String, String> authHeaders) {
+        this.transport = transport;
         if (!baseUrl.endsWith("/")) {
             baseUrl += "/";
         }
@@ -67,33 +62,7 @@ public A2ACardResolver(A2AHttpClient httpClient, String baseUrl, String agentCar
      * @throws A2AClientJSONError f the response body cannot be decoded as JSON or validated against the AgentCard schema
      */
     public AgentCard getAgentCard() throws A2AClientError, A2AClientJSONError {
-        A2AHttpClient.GetBuilder builder = httpClient.createGet()
-                .url(url)
-                .addHeader("Content-Type", "application/json");
-
-        if (authHeaders != null) {
-            for (Map.Entry<String, String> entry : authHeaders.entrySet()) {
-                builder.addHeader(entry.getKey(), entry.getValue());
-            }
-        }
-
-        String body;
-        try {
-            A2AHttpResponse response = builder.get();
-            if (!response.success()) {
-                throw new A2AClientError("Failed to obtain agent card: " + response.status());
-            }
-            body = response.body();
-        } catch (IOException | InterruptedException e) {
-            throw new A2AClientError("Failed to obtain agent card", e);
-        }
-
-        try {
-            return unmarshalFrom(body, AGENT_CARD_TYPE_REFERENCE);
-        } catch (JsonProcessingException e) {
-            throw new A2AClientJSONError("Could not unmarshal agent card response", e);
-        }
-
+        return transport.getAgentCard(url, authHeaders);
     }