d2f2f87bbe
Add an (almost) complete implementation of the streamable HTTP transport, including: - A StreamableHTTPHandler for serving sessions. - A StreamableHTTPServerTransport that supports session resumption. - A minimal StreamableHTTPClientTransport. Additionally, include the following minor changes: - Refactor SSE event reading to use an iterator. - Start to to aliases for JSON-RPC types (incomplete) - Fix handling for null tool arguments (again) Still to do: - The streamable client does not support retry/resumption, or the side-channel GET requests. - Support configurable session and event retention (garbage collection). - Expose the HTTP client used for HTTP requests (for auth). Change-Id: Ieba216ef901169b4660d601386fa0c7c7bb4c4b2 Reviewed-on: https://go-review.googlesource.com/c/tools/+/667515 Reviewed-by: Jonathan Amsterdam <jba@google.com> LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
95 lines
2.6 KiB
Go
95 lines
2.6 KiB
Go
// Copyright 2025 The Go MCP SDK Authors. All rights reserved.
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// Use of this source code is governed by an MIT-style
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// license that can be found in the LICENSE file.
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package main
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import (
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"context"
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"flag"
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"fmt"
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"log"
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"net/http"
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"net/url"
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"os"
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"github.com/modelcontextprotocol/go-sdk/mcp"
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)
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var httpAddr = flag.String("http", "", "if set, use streamable HTTP at this address, instead of stdin/stdout")
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type HiArgs struct {
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Name string `json:"name"`
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}
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func SayHi(ctx context.Context, ss *mcp.ServerSession, params *mcp.CallToolParamsFor[HiArgs]) (*mcp.CallToolResultFor[struct{}], error) {
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return &mcp.CallToolResultFor[struct{}]{
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Content: []*mcp.Content{
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mcp.NewTextContent("Hi " + params.Name),
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},
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}, nil
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}
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// TODO(jba): it should be OK for args to be a pointer, but this fails in
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// jsonschema. Needs investigation.
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func PromptHi(ctx context.Context, ss *mcp.ServerSession, args HiArgs, params *mcp.GetPromptParams) (*mcp.GetPromptResult, error) {
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return &mcp.GetPromptResult{
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Description: "Code review prompt",
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Messages: []*mcp.PromptMessage{
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{Role: "user", Content: mcp.NewTextContent("Say hi to " + params.Name)},
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},
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}, nil
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}
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func main() {
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flag.Parse()
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server := mcp.NewServer("greeter", "v0.0.1", nil)
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server.AddTools(mcp.NewTool("greet", "say hi", SayHi, mcp.Input(
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mcp.Property("name", mcp.Description("the name to say hi to")),
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)))
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server.AddPrompts(mcp.NewPrompt("greet", "", PromptHi))
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server.AddResources(&mcp.ServerResource{
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Resource: &mcp.Resource{
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Name: "info",
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MIMEType: "text/plain",
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URI: "embedded:info",
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},
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Handler: handleEmbeddedResource,
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})
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if *httpAddr != "" {
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handler := mcp.NewStreamableHTTPHandler(func(*http.Request) *mcp.Server {
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return server
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}, nil)
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log.Printf("MCP handler listening at %s", *httpAddr)
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http.ListenAndServe(*httpAddr, handler)
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} else {
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t := mcp.NewLoggingTransport(mcp.NewStdIOTransport(), os.Stderr)
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if err := server.Run(context.Background(), t); err != nil {
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log.Printf("Server failed: %v", err)
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}
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}
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}
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var embeddedResources = map[string]string{
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"info": "This is the hello example server.",
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}
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func handleEmbeddedResource(_ context.Context, _ *mcp.ServerSession, params *mcp.ReadResourceParams) (*mcp.ReadResourceResult, error) {
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u, err := url.Parse(params.URI)
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if err != nil {
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return nil, err
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}
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if u.Scheme != "embedded" {
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return nil, fmt.Errorf("wrong scheme: %q", u.Scheme)
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}
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key := u.Opaque
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text, ok := embeddedResources[key]
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if !ok {
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return nil, fmt.Errorf("no embedded resource named %q", key)
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}
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return &mcp.ReadResourceResult{
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Contents: []*mcp.ResourceContents{mcp.NewTextResourceContents(params.URI, "text/plain", text)},
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}, nil
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}
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