Improve client initialization with streamlined config and HTTP client support

ballerina/Ballerina.toml

@@ -1,7 +1,7 @@
 [package]
 org = "ballerina"
 name = "mcp"
-version = "0.4.0"
+version = "0.4.1"
 authors = ["Ballerina"]
 keywords = ["mcp"]
 repository = "https://github.com/ballerina-platform/module-ballerina-mcp"
@@ -15,5 +15,5 @@ graalvmCompatible = true
 [[platform.java21.dependency]]
 groupId = "io.ballerina.stdlib."
 artifactId = "mcp-native"
-version = "0.4.0"
-path = "../native/build/libs/mcp-native-0.4.0.jar"
+version = "0.4.1"
+path = "../native/build/libs/mcp-native-0.4.1-SNAPSHOT.jar"

ballerina/Dependencies.toml

@@ -70,7 +70,7 @@ dependencies = [
 [[package]]
 org = "ballerina"
 name = "http"
-version = "2.14.1"
+version = "2.14.2"
 dependencies = [
 	{org = "ballerina", name = "auth"},
 	{org = "ballerina", name = "cache"},
@@ -108,6 +108,9 @@ dependencies = [
 	{org = "ballerina", name = "jballerina.java"},
 	{org = "ballerina", name = "lang.value"}
 ]
+modules = [
+	{org = "ballerina", packageName = "io", moduleName = "io"}
+]
 
 [[package]]
 org = "ballerina"
@@ -220,9 +223,10 @@ dependencies = [
 [[package]]
 org = "ballerina"
 name = "mcp"
-version = "0.4.0"
+version = "0.4.1"
 dependencies = [
 	{org = "ballerina", name = "http"},
+	{org = "ballerina", name = "io"},
 	{org = "ballerina", name = "jballerina.java"}
 ]
 modules = [

ballerina/client.bal

@@ -15,11 +15,20 @@
 // under the License.
 
 # Configuration options for initializing an MCP client.
-#
-# + capabilities - Capabilities to be advertised by this client.
 public type ClientConfiguration record {|
-    *ProtocolOptions;
+    *StreamableHttpClientTransportConfig;
+    # Client information such as name and version.
+    Implementation info;
+    # Client capabilities configuration.
+    ClientCapabilityConfiguration capabilityConfig?;
+|};
+
+# Configuration options for initializing an MCP client.
+public type ClientCapabilityConfiguration record {|
+    # Capabilities to be advertised by this client.
     ClientCapabilities capabilities?;
+    # Whether to enforce strict capabilities compliance.
+    boolean enforceStrictCapabilities?;
 |};
 
 # Represents an MCP client built on top of the Streamable HTTP transport.
@@ -45,10 +54,10 @@ public distinct isolated client class Client {
     # + serverUrl - MCP server URL.
     # + clientInfo - Client details, such as name and version.
     # + config - Optional configuration containing client capabilities.
-    public isolated function init(string serverUrl, Implementation clientInfo, ClientConfiguration? config = ()) {
+    public isolated function init(string serverUrl, *ClientConfiguration config) {
         self.serverUrl = serverUrl;
-        self.clientInfo = clientInfo.cloneReadOnly();
-        self.clientCapabilities = config?.capabilities.cloneReadOnly() ?: {};
+        self.clientInfo = config.info.cloneReadOnly();
+        self.clientCapabilities = (config.capabilityConfig?.capabilities).cloneReadOnly() ?: {};
     }
 
     # Establishes a connection to the MCP server and performs protocol initialization.
@@ -84,7 +93,9 @@ public distinct isolated client class Client {
                 // Validate protocol compatibility.
                 if (!SUPPORTED_PROTOCOL_VERSIONS.some(v => v == protocolVersion)) {
                     return error ProtocolVersionError(
-                        string `Server protocol version '${protocolVersion}' is not supported. Supported versions: ${SUPPORTED_PROTOCOL_VERSIONS.toString()}.`
+                        string `Server protocol version '${
+                            protocolVersion}' is not supported. Supported versions: ${
+                            SUPPORTED_PROTOCOL_VERSIONS.toString()}.`
                     );
                 }
 
@@ -99,7 +110,8 @@ public distinct isolated client class Client {
                 check self.sendNotificationMessage(initNotification);
             } else {
                 return error ClientInitializationError(
-                    string `Initialization failed: unexpected response type '${(typeof response).toString()}' received from server.`
+                    string `Initialization failed: unexpected response type '${
+                        (typeof response).toString()}' received from server.`
                 );
             }
         }
@@ -113,7 +125,7 @@ public distinct isolated client class Client {
             StreamableHttpClientTransport? currentTransport = self.transport;
             if currentTransport is () {
                 return error UninitializedTransportError(
-                    "Subscription failed: client transport is not initialized. Call initialize() first."
+                    "Subscription failed: client transport is not initialized."
                 );
             }
             return currentTransport.establishEventStream();
@@ -166,7 +178,7 @@ public distinct isolated client class Client {
             StreamableHttpClientTransport? currentTransport = self.transport;
             if currentTransport is () {
                 return error UninitializedTransportError(
-                    "Closure failed: client transport is not initialized. Call initialize() first."
+                    "Closure failed: client transport is not initialized."
                 );
             }
 
@@ -193,7 +205,7 @@ public distinct isolated client class Client {
             StreamableHttpClientTransport? currentTransport = self.transport;
             if currentTransport is () {
                 return error UninitializedTransportError(
-                    "Cannot send request: client transport is not initialized. Call initialize() first."
+                    "Cannot send request: client transport is not initialized."
                 );
             }
 
@@ -222,7 +234,7 @@ public distinct isolated client class Client {
             StreamableHttpClientTransport? currentTransport = self.transport;
             if currentTransport is () {
                 return error UninitializedTransportError(
-                "Cannot send notification: client transport is not initialized. Call initialize() first."
+                "Cannot send notification: client transport is not initialized."
                 );
             }
 

ballerina/error.bal

@@ -38,9 +38,6 @@ public type JsonRpcMessageTransformationError distinct StreamError;
 # Error when required data is missing from an SSE event.
 public type MissingSseDataError distinct JsonRpcMessageTransformationError;
 
-# Error for JSON parsing failures within SSE event data.
-public type JsonParsingError distinct JsonRpcMessageTransformationError;
-
 # Error for failures converting JSON to JsonRpcMessage.
 public type TypeConversionError distinct JsonRpcMessageTransformationError;
 

ballerina/json_rpc_message_stream_transformer.bal

@@ -96,12 +96,7 @@ isolated class JsonRpcMessageStreamTransformer {
             return error MissingSseDataError("SSE event is missing the required 'data' field.");
         }
 
-        json|error jsonData = eventData.fromJsonString();
-        if jsonData is error {
-            return error JsonParsingError(string `Failed to parse SSE event data as JSON: ${jsonData.message()}`);
-        }
-
-        JsonRpcMessage|error message = jsonData.cloneWithType(JsonRpcMessage);
+        JsonRpcMessage|error message = eventData.fromJsonStringWithType();
         if message is error {
             return error TypeConversionError(string `Failed to convert JSON data to JsonRpcMessage: ${message.message()}`);
         }

ballerina/streamable_http.bal

@@ -20,7 +20,8 @@ import ballerina/http;
 #
 # + sessionId - Optional session identifier for continued interactions.
 type StreamableHttpClientTransportConfig record {|
-    string? sessionId = ();
+    *http:ClientConfiguration;
+    string sessionId?;
 |};
 
 # Provides HTTP-based client transport with support for streaming.
@@ -34,14 +35,16 @@ isolated class StreamableHttpClientTransport {
     # + serverUrl - The URL of the server endpoint.
     # + config - Optional configuration, such as session ID.
     # + return - A StreamableHttpTransportError if initialization fails; otherwise, nil.
-    isolated function init(string serverUrl, StreamableHttpClientTransportConfig? config = ()) returns StreamableHttpTransportError? {
+    isolated function init(string serverUrl, *StreamableHttpClientTransportConfig config) returns StreamableHttpTransportError? {
         self.serverUrl = serverUrl;
+
+        StreamableHttpClientTransportConfig {sessionId, ...clientConfig} = config;
         do {
-            self.httpClient = check new (serverUrl);
+            self.httpClient = check new (serverUrl, clientConfig);
         } on fail error e {
             return error HttpClientError(string `Unable to initialize HTTP client for '${serverUrl}': ${e.message()}`);
         }
-        self.sessionId = config?.sessionId;
+        self.sessionId = sessionId;
     }
 
     # Sends a JSON-RPC message to the server and returns the response.
@@ -65,7 +68,7 @@ isolated class StreamableHttpClientTransport {
             }
 
             // If response is 202 Accepted, there is no content to process.
-            if response.statusCode == 202 {
+            if response.statusCode == http:STATUS_ACCEPTED {
                 return;
             }
 
@@ -134,7 +137,7 @@ isolated class StreamableHttpClientTransport {
     }
 
     # Returns the current session ID, or nil if no session is active.
-    # 
+    #
     # + return - The current session ID as a string, or nil if not set.
     isolated function getSessionId() returns string? {
         lock {

ballerina/types.bal

@@ -26,6 +26,16 @@ public const SUPPORTED_PROTOCOL_VERSIONS = [
 
 public const JSONRPC_VERSION = "2.0";
 
+# Notification methods
+public const NOTIFICATION_INITIALIZED = "notifications/initialized";
+public const NOTIFICATION_CANCELLED = "notifications/cancelled";
+public const NOTIFICATION_PROGRESS = "notifications/progress";
+public const NOTIFICATION_RESOURCES_LIST_CHANGED = "notifications/resources/list_changed";
+public const NOTIFICATION_RESOURCES_UPDATED = "notifications/resources/updated";
+public const NOTIFICATION_PROMPTS_LIST_CHANGED = "notifications/prompts/list_changed";
+public const NOTIFICATION_TOOLS_LIST_CHANGED = "notifications/tools/list_changed";
+public const NOTIFICATION_MESSAGE = "notifications/message";
+
 # A progress token, used to associate progress notifications with the original request.
 public type ProgressToken string|int;
 
@@ -123,7 +133,7 @@ public type EmptyResult Result;
 public type CancelledNotification record {|
     *Notification;
     # The method name for this notification
-    "notifications/cancelled" method;
+    NOTIFICATION_CANCELLED method;
     # The parameters for the cancellation notification
     record {|
         # The ID of the request to cancel.
@@ -173,14 +183,12 @@ public type InitializeResult record {|
 public type InitializedNotification record {|
     *Notification;
     # The method identifier for the notification, must be "notifications/initialized"
-    "notifications/initialized" method;
+    NOTIFICATION_INITIALIZED method;
 |};
 
 # Capabilities a client may support. Known capabilities are defined here, in this schema,
 # but this is not a closed set: any client can define its own, additional capabilities.
 public type ClientCapabilities record {
-    # Experimental, non-standard capabilities that the client supports.
-    record {|record {}...;|} experimental?;
     # Present if the client supports listing roots.
     record {|
         # Whether the client supports notifications for changes to the roots list.
@@ -239,7 +247,7 @@ public type PingRequest record {|
 public type ProgressNotification record {|
     *Notification;
     # The method name for the notification
-    "notifications/progress" method;
+    NOTIFICATION_PROGRESS method;
     # The parameters for the progress notification
     record {
         # The progress token which was given in the initial request, 
@@ -278,14 +286,14 @@ public type PaginatedResult record {|
 public type ResourceListChangedNotification record {|
     *Notification;
     # The JSON-RPC method name for resource list changed notifications
-    "notifications/resources/list_changed" method;
+    NOTIFICATION_RESOURCES_LIST_CHANGED method;
 |};
 
 # A notification from the server to the client, informing it that a resource has changed and may need to be read again.
 public type ResourceUpdatedNotification record {|
     *Notification;
     # The JSON-RPC method name for resource updated notifications
-    "notifications/resources/updated" method;
+    NOTIFICATION_RESOURCES_UPDATED method;
     # The parameters for the resource updated notification
     record {
         # The URI of the resource that has been updated. This might be a sub-resource of the one 
@@ -335,7 +343,7 @@ public type EmbeddedResource record {|
 public type PromptListChangedNotification record {|
     *Notification;
     # The JSON-RPC method name for prompt list changed notifications
-    "notifications/prompts/list_changed" method;
+    NOTIFICATION_PROMPTS_LIST_CHANGED method;
 |};
 
 # Sent from the client to request a list of tools the server has.
@@ -382,7 +390,7 @@ public type CallToolParams record {|
 public type ToolListChangedNotification record {|
     *Notification;
     # The JSON-RPC method name for tool list changed notifications
-    "notifications/tools/list_changed" method;
+    NOTIFICATION_TOOLS_LIST_CHANGED method;
 |};
 
 # Additional properties describing a Tool to clients.
@@ -433,7 +441,7 @@ public type Tool record {|
 public type LoggingMessageNotification record {|
     *Notification;
     # The method name for the notification
-    "notifications/message" method;
+    NOTIFICATION_MESSAGE method;
     # The parameters for the logging message notification
     record {
         # The severity of this log message.

ballerina/utils.bal

@@ -72,3 +72,4 @@ isolated function extractResultFromMessage(JsonRpcMessage message) returns Serve
     }
     return error InvalidMessageTypeError("Received message from server is not a valid JsonRpcResponse.");
 }
+