c01fd188d2Summary
Builds on the types and architecture from the previous PR to deliver a
working variant-aware MCP
server that routes requests to inner mcp.Server instances based on
per-request _meta variant selection,
enabling a single MCP endpoint to serve multiple tool/resource/prompt
variants simultaneously.
```go
// Create standard mcp.Server instances — one per variant
codeReviewServer := mcp.NewServer(&mcp.Implementation{Name:
"devplatform", Version: "v1.0.0"}, nil)
mcp.AddTool(codeReviewServer, &mcp.Tool{Name: "list_pull_requests",
...}, handler)
mcp.AddTool(codeReviewServer, &mcp.Tool{Name: "get_diff", ...}, handler)
pmServer := mcp.NewServer(&mcp.Implementation{Name: "devplatform",
Version: "v1.0.0"}, nil)
mcp.AddTool(pmServer, &mcp.Tool{Name: "list_issues", ...}, handler)
mcp.AddTool(pmServer, &mcp.Tool{Name: "create_issue", ...}, handler)
// Register them as variants on a single server
vs := variants.NewServer(&mcp.Implementation{Name: "devplatform",
Version: "v1.0.0"}).
WithVariant(variants.ServerVariant{
ID: "code-review",
Description: "PR and code review operations",
Status: variants.Stable,
}, codeReviewServer, 0).
WithVariant(variants.ServerVariant{
ID: "project-management",
Description: "Issue and project tracking operations",
Status: variants.Stable,
}, pmServer, 1)
// Future: register variants backed by remote MCP servers
// WithHTTPVariant(v, mcpServer, priority) — variant backed by an
mcp.Server exposed over HTTP
// WithRemoteVariant(v, "https://...", priority) — variant backed by a
remote MCP endpoint
// Serve over HTTP for multiple concurrent clients
handler := variants.NewStreamableHTTPHandler(vs, nil)
http.ListenAndServe(":8080", handler)
// Or serve over stdio for single-client use:
// vs.Run(ctx, &mcp.StdioTransport{})
```
Key additions
- Backend abstraction (inMemoryBackend) — creates in-memory transport pairs between the variant server and
inner mcp.Server instances, with notification forwarding for progress and logging events.
- Request dispatcher (dispatch.go) — handles routing for tools/list, tools/call, resources/list,
resources/read, resources/subscribe, prompts/list, prompts/get, and completion/complete methods.
Implements variant-scoped cursor wrapping to correctly paginate across multiple inner servers.
- Session middleware (session.go) — manages per-session inner connections in stateful mode and shared
connections in stateless HTTP mode, ensuring proper lifecycle management.
- Initialize enrichment — injects availableVariants into the server's capabilities response so clients can
discover which variants are available.
- Capability discovery — merges inner server capabilities via union to present a unified capability set to
clients.
- NewStreamableHTTPHandler — provides an HTTP handler for multi-client serving over Streamable HTTP
transport.
- Integration tests (server_test.go, 458 lines) — covers end-to-end variant selection, backward
compatibility (no variant specified), HTTP transport, and stateless modes.
- Examples — stdio-based (examples/server/variants/main.go) and HTTP-based
(examples/server/variants-http/main.go) example servers demonstrating the API.
- README — rewritten with API documentation and architecture diagrams.
TODO (subsequent PRs):
- Unit Testing
- More integration tests
Signed-off-by: Kurt Degiorgio <kdegiorgio@bloomberg.net>
24 lines
2.1 KiB
Text
24 lines
2.1 KiB
Text
github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
|
|
github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
|
|
github.com/golang-jwt/jwt/v5 v5.2.2 h1:Rl4B7itRWVtYIHFrSNd7vhTiz9UpLdi6gZhZ3wEeDy8=
|
|
github.com/golang-jwt/jwt/v5 v5.2.2/go.mod h1:pqrtFR0X4osieyHYxtmOUWsAWrfe1Q5UVIyoH402zdk=
|
|
github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
|
|
github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
|
|
github.com/google/jsonschema-go v0.3.0 h1:6AH2TxVNtk3IlvkkhjrtbUc4S8AvO0Xii0DxIygDg+Q=
|
|
github.com/google/jsonschema-go v0.3.0/go.mod h1:r5quNTdLOYEz95Ru18zA0ydNbBuYoo9tgaYcxEYhJVE=
|
|
github.com/modelcontextprotocol/go-sdk v1.2.0 h1:Y23co09300CEk8iZ/tMxIX1dVmKZkzoSBZOpJwUnc/s=
|
|
github.com/modelcontextprotocol/go-sdk v1.2.0/go.mod h1:6fM3LCm3yV7pAs8isnKLn07oKtB0MP9LHd3DfAcKw10=
|
|
github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
|
|
github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
|
|
github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu7U=
|
|
github.com/stretchr/testify v1.11.1/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
|
|
github.com/yosida95/uritemplate/v3 v3.0.2 h1:Ed3Oyj9yrmi9087+NczuL5BwkIc4wvTb5zIM+UJPGz4=
|
|
github.com/yosida95/uritemplate/v3 v3.0.2/go.mod h1:ILOh0sOhIJR3+L/8afwt/kE++YT040gmv5BQTMR2HP4=
|
|
golang.org/x/oauth2 v0.30.0 h1:dnDm7JmhM45NNpd8FDDeLhK6FwqbOf4MLCM9zb1BOHI=
|
|
golang.org/x/oauth2 v0.30.0/go.mod h1:B++QgG3ZKulg6sRPGD/mqlHQs5rB3Ml9erfeDY7xKlU=
|
|
golang.org/x/tools v0.34.0 h1:qIpSLOxeCYGg9TrcJokLBG4KFA6d795g0xkBkiESGlo=
|
|
golang.org/x/tools v0.34.0/go.mod h1:pAP9OwEaY1CAW3HOmg3hLZC5Z0CCmzjAF2UQMSqNARg=
|
|
gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
|
|
gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
|
|
gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
|
|
gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
|