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Document Client usage with HTTPClientTransport (#77)

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* Add test coverage for Client with HTTPClientTransport

* Configure HTTP client transport to stream by default

* Add example usage of streaming HTTP transport to README

* Explicitly set streaming to false in test
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Mattt 2025-04-27 09:29:24 -07:00 • committed by GitHub
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3 changed files with 222 additions and 20 deletions
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23
README.md
View file

@ -39,6 +39,29 @@ try await client.connect(transport: transport)
let result = try await client.initialize()
```
### Streaming HTTP Transport
The HTTP transport supports streaming mode for real-time communication using Server-Sent Events (SSE):
```swift
import MCP
// Create a streaming HTTP transport
let transport = HTTPClientTransport(
endpoint: URL(string: "http://localhost:8080")!,
)
// Initialize the client with streaming transport
let client = Client(name: "MyApp", version: "1.0.0")
try await client.connect(transport: transport)
// Initialize the connection
let result = try await client.initialize()
// The transport will automatically handle SSE events
// and deliver them through the client's notification handlers
```
### Basic Server Setup
```swift

4
Sources/MCP/Base/Transports/HTTPClientTransport.swift
View file

@ -21,7 +21,7 @@ public actor HTTPClientTransport: Actor, Transport {
public init(
endpoint: URL,
configuration: URLSessionConfiguration = .default,
streaming: Bool = false,
streaming: Bool = true,
logger: Logger? = nil
) {
self.init(
@ -269,7 +269,7 @@ public actor HTTPClientTransport: Actor, Transport {
if line.hasSuffix("\r") {
line = line.dropLast()
}
// Lines starting with ":" are comments
if line.hasPrefix(":") { continue }

215
Tests/MCPTests/HTTPClientTransportTests.swift
View file

@ -51,7 +51,11 @@ import Testing
func executeHandler(for request: URLRequest) async throws -> (HTTPURLResponse, Data) {
guard let handler = requestHandler else {
throw MockURLProtocolError.noRequestHandler
throw NSError(
domain: "MockURLProtocolError", code: 0,
userInfo: [
NSLocalizedDescriptionKey: "No request handler set"
])
}
return try await handler(request)
}
@ -123,11 +127,6 @@ import Testing
override func stopLoading() {}
}
enum MockURLProtocolError: Swift.Error {
case noRequestHandler
case invalidURL
}
// MARK: -
@Suite("HTTP Client Transport Tests", .serialized)
@ -140,7 +139,11 @@ import Testing
configuration.protocolClasses = [MockURLProtocol.self]
let transport = HTTPClientTransport(
endpoint: testEndpoint, configuration: configuration, streaming: false, logger: nil)
endpoint: testEndpoint,
configuration: configuration,
streaming: false,
logger: nil
)
try await transport.connect()
await transport.disconnect()
@ -152,7 +155,11 @@ import Testing
configuration.protocolClasses = [MockURLProtocol.self]
let transport = HTTPClientTransport(
endpoint: testEndpoint, configuration: configuration, streaming: false, logger: nil)
endpoint: testEndpoint,
configuration: configuration,
streaming: false,
logger: nil
)
try await transport.connect()
let messageData = #"{"jsonrpc":"2.0","method":"initialize","id":1}"#.data(using: .utf8)!
@ -190,7 +197,11 @@ import Testing
configuration.protocolClasses = [MockURLProtocol.self]
let transport = HTTPClientTransport(
endpoint: testEndpoint, configuration: configuration, streaming: false, logger: nil)
endpoint: testEndpoint,
configuration: configuration,
streaming: false,
logger: nil
)
try await transport.connect()
let messageData = #"{"jsonrpc":"2.0","method":"initialize","id":1}"#.data(using: .utf8)!
@ -220,7 +231,11 @@ import Testing
configuration.protocolClasses = [MockURLProtocol.self]
let transport = HTTPClientTransport(
endpoint: testEndpoint, configuration: configuration, streaming: false, logger: nil)
endpoint: testEndpoint,
configuration: configuration,
streaming: false,
logger: nil
)
try await transport.connect()
let initialSessionID = "existing-session-abc"
@ -265,7 +280,11 @@ import Testing
configuration.protocolClasses = [MockURLProtocol.self]
let transport = HTTPClientTransport(
endpoint: testEndpoint, configuration: configuration)
endpoint: testEndpoint,
configuration: configuration,
streaming: false,
logger: nil
)
try await transport.connect()
let messageData = #"{"jsonrpc":"2.0","method":"test","id":3}"#.data(using: .utf8)!
@ -298,7 +317,11 @@ import Testing
configuration.protocolClasses = [MockURLProtocol.self]
let transport = HTTPClientTransport(
endpoint: testEndpoint, configuration: configuration)
endpoint: testEndpoint,
configuration: configuration,
streaming: false,
logger: nil
)
try await transport.connect()
let messageData = #"{"jsonrpc":"2.0","method":"test","id":4}"#.data(using: .utf8)!
@ -331,7 +354,11 @@ import Testing
configuration.protocolClasses = [MockURLProtocol.self]
let transport = HTTPClientTransport(
endpoint: testEndpoint, configuration: configuration)
endpoint: testEndpoint,
configuration: configuration,
streaming: false,
logger: nil
)
try await transport.connect()
let initialSessionID = "expired-session-xyz"
@ -385,8 +412,11 @@ import Testing
configuration.protocolClasses = [MockURLProtocol.self]
let transport = HTTPClientTransport(
endpoint: testEndpoint, configuration: configuration, streaming: true,
logger: nil)
endpoint: testEndpoint,
configuration: configuration,
streaming: true,
logger: nil
)
let eventString = "id: event1\ndata: {\"key\":\"value\"}\n\n"
let sseEventData = eventString.data(using: .utf8)!
@ -419,8 +449,11 @@ import Testing
configuration.protocolClasses = [MockURLProtocol.self]
let transport = HTTPClientTransport(
endpoint: testEndpoint, configuration: configuration, streaming: true,
logger: nil)
endpoint: testEndpoint,
configuration: configuration,
streaming: true,
logger: nil
)
let eventString = "id: event1\r\ndata: {\"key\":\"value\"}\r\n\n"
let sseEventData = eventString.data(using: .utf8)!
@ -448,6 +481,152 @@ import Testing
#expect(receivedData == expectedData)
}
#endif // !canImport(FoundationNetworking)
}
@Test(
"Client with HTTP Transport complete flow", .httpClientTransportSetup,
.timeLimit(.minutes(1)))
func testClientFlow() async throws {
let configuration = URLSessionConfiguration.ephemeral
configuration.protocolClasses = [MockURLProtocol.self]
let transport = HTTPClientTransport(
endpoint: testEndpoint,
configuration: configuration,
streaming: false,
logger: nil
)
let client = Client(name: "TestClient", version: "1.0.0")
// Use an actor to track request sequence
actor RequestTracker {
enum RequestType {
case initialize
case callTool
}
private(set) var lastRequest: RequestType?
func setRequest(_ type: RequestType) {
lastRequest = type
}
func getLastRequest() -> RequestType? {
return lastRequest
}
}
let tracker = RequestTracker()
// Setup mock responses
await MockURLProtocol.requestHandlerStorage.setHandler {
[testEndpoint, tracker] (request: URLRequest) in
switch request.httpMethod {
case "GET":
#expect(
request.allHTTPHeaderFields?["Accept"]?.contains("text/event-stream")
== true)
case "POST":
#expect(
request.allHTTPHeaderFields?["Accept"]?.contains("application/json") == true
)
default:
Issue.record(
"Unsupported HTTP method \(String(describing: request.httpMethod))")
}
#expect(request.url == testEndpoint)
let bodyData = request.readBody()
guard let bodyData = bodyData,
let json = try JSONSerialization.jsonObject(with: bodyData) as? [String: Any],
let method = json["method"] as? String
else {
throw NSError(
domain: "MockURLProtocolError", code: 0,
userInfo: [
NSLocalizedDescriptionKey: "Invalid JSON-RPC message \(#file):\(#line)"
])
}
if method == "initialize" {
await tracker.setRequest(.initialize)
let requestID = json["id"] as! String
let result = Initialize.Result(
protocolVersion: Version.latest,
capabilities: .init(tools: .init()),
serverInfo: .init(name: "Mock Server", version: "0.0.1"),
instructions: nil
)
let response = Initialize.response(id: .string(requestID), result: result)
let responseData = try JSONEncoder().encode(response)
let httpResponse = HTTPURLResponse(
url: testEndpoint, statusCode: 200, httpVersion: "HTTP/1.1",
headerFields: ["Content-Type": "application/json"])!
return (httpResponse, responseData)
} else if method == "tools/call" {
// Verify initialize was called first
if let lastRequest = await tracker.getLastRequest(), lastRequest != .initialize
{
#expect(Bool(false), "Initialize should be called before callTool")
}
await tracker.setRequest(.callTool)
let params = json["params"] as? [String: Any]
let toolName = params?["name"] as? String
#expect(toolName == "calculator")
let requestID = json["id"] as! String
let result = CallTool.Result(content: [.text("42")])
let response = CallTool.response(id: .string(requestID), result: result)
let responseData = try JSONEncoder().encode(response)
let httpResponse = HTTPURLResponse(
url: testEndpoint, statusCode: 200, httpVersion: "HTTP/1.1",
headerFields: ["Content-Type": "application/json"])!
return (httpResponse, responseData)
} else if method == "notifications/initialized" {
// Ignore initialized notifications
let httpResponse = HTTPURLResponse(
url: testEndpoint, statusCode: 200, httpVersion: "HTTP/1.1",
headerFields: ["Content-Type": "application/json"])!
return (httpResponse, Data())
} else {
throw NSError(
domain: "MockURLProtocolError", code: 0,
userInfo: [
NSLocalizedDescriptionKey:
"Unexpected request method: \(method) \(#file):\(#line)"
])
}
}
// Execute the complete flow
try await client.connect(transport: transport)
// Step 1: Initialize client
let initResult = try await client.initialize()
#expect(initResult.protocolVersion == Version.latest)
#expect(initResult.capabilities.tools != nil)
// Step 2: Call a tool
let toolResult = try await client.callTool(name: "calculator")
#expect(toolResult.content.count == 1)
if case let .text(text) = toolResult.content[0] {
#expect(text == "42")
} else {
#expect(Bool(false), "Expected text content")
}
// Step 3: Verify request sequence
#expect(await tracker.getLastRequest() == .callTool)
// Step 4: Disconnect
await client.disconnect()
}
}
#endif // swift(>=6.1)