Class: A2A::Bindings::JsonRpc

Inherits:
Object
  • Object
show all
Defined in:
lib/a2a/bindings/json_rpc.rb

Overview

Rack middleware implementing the A2A JSON-RPC 2.0 protocol binding.

Strips the JSON-RPC envelope from the inbound request, setting env keys for the method name, request id, and parsed params. Calls downstream. On return, wraps env back into a JSON-RPC response envelope.

Streaming operations (SendStreamingMessage, SubscribeToTask): When the handler sets env to an SSE::Stream (which is a Protocol::HTTP::Body::Writable, which is a Readable), Falcon’s protocol-rack passes it through untouched. True async streaming with backpressure — no Thread::Queue, no #each polling.

Instance Method Summary collapse

Constructor Details

#initialize(app) ⇒ JsonRpc

Returns a new instance of JsonRpc.



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# File 'lib/a2a/bindings/json_rpc.rb', line 23

def initialize(app)
  @app = app
end

Instance Method Details

#call(env) ⇒ Object 



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# File 'lib/a2a/bindings/json_rpc.rb', line 27

def call(env)
  req  = Rack::Request.new(env)
  body = req.body.read
  req.body.rewind

  begin
    rpc = JSON.parse(body)
  rescue JSON::ParserError
    return error_response(nil, -32700, "Parse error")
  end

  unless rpc.is_a?(Hash) && rpc["jsonrpc"] == "2.0"
    return error_response(nil, -32600, "Invalid Request")
  end

  id     = rpc["id"]
  method = rpc["method"]
  params = rpc["params"] || {}

  env["a2a.json_rpc_id"]     = id
  env["a2a.json_rpc_method"] = method
  env["a2a.body"]            = params

  @app.call(env)

  # Check if handler signalled a JSON-RPC error
  if (err = env["a2a.error"])
    return error_response(id, err[:code], err[:message], err[:data])
  end

  # Check if handler set up a streaming response.
  # The stream is an SSE::Stream (Protocol::HTTP::Body::Readable).
  if (stream = env["a2a.stream"])
    return [200, A2A::SSE::Stream.headers, stream]
  end

  result = env["a2a.result"]
  success_response(id, result)
end