64 lines
1.7 KiB
TypeScript
64 lines
1.7 KiB
TypeScript
import type { Transport } from '@modelcontextprotocol/sdk/shared/transport.js'
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import type { JSONRPCMessage } from '@modelcontextprotocol/sdk/types.js'
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/**
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* In-process linked transport pair for running an MCP server and client
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* in the same process without spawning a subprocess.
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*
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* `send()` on one side delivers to `onmessage` on the other.
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* `close()` on either side calls `onclose` on both.
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*/
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class InProcessTransport implements Transport {
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private peer: InProcessTransport | undefined
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private closed = false
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onclose?: () => void
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onerror?: (error: Error) => void
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onmessage?: (message: JSONRPCMessage) => void
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/** @internal */
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_setPeer(peer: InProcessTransport): void {
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this.peer = peer
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}
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async start(): Promise<void> {}
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async send(message: JSONRPCMessage): Promise<void> {
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if (this.closed) {
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throw new Error('Transport is closed')
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}
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// Deliver to the other side asynchronously to avoid stack depth issues
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// with synchronous request/response cycles
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queueMicrotask(() => {
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this.peer?.onmessage?.(message)
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})
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}
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async close(): Promise<void> {
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if (this.closed) {
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return
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}
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this.closed = true
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this.onclose?.()
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// Close the peer if it hasn't already closed
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if (this.peer && !this.peer.closed) {
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this.peer.closed = true
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this.peer.onclose?.()
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}
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}
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}
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/**
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* Creates a pair of linked transports for in-process MCP communication.
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* Messages sent on one transport are delivered to the other's `onmessage`.
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*
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* @returns [clientTransport, serverTransport]
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*/
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export function createLinkedTransportPair(): [Transport, Transport] {
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const a = new InProcessTransport()
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const b = new InProcessTransport()
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a._setPeer(b)
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b._setPeer(a)
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return [a, b]
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}
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