1823aae891Co-authored-by: Matt <77928207+mattzcarey@users.noreply.github.com> Co-authored-by: Konstantin Konstantinov <KKonstantinov@users.noreply.github.com> Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
48 lines
2.1 KiB
TypeScript
48 lines
2.1 KiB
TypeScript
/**
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* SSE Polling Example Client (SEP-1699)
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*
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* Connects (2025-era), calls `long-operation`, and asserts the result arrives
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* AFTER the server's mid-stream `closeSSE()` — i.e. the client transport
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* automatically reconnects with `Last-Event-ID` and replays the events the
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* `eventStore` buffered while disconnected. Also asserts every progress log
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* (including the one emitted while disconnected) was delivered.
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*/
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import { check, parseExampleArgs } from '@mcp-examples/shared';
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import { Client, StreamableHTTPClientTransport } from '@modelcontextprotocol/client';
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const { url } = parseExampleArgs();
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// `closeSSE`/`eventStore` live on the sessionful-2025 transport, so this
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// story is legacy-only by design — it was previously reaching 2025 by
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// negotiation fallback; pin it.
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const client = new Client({ name: 'sse-polling-client', version: '1.0.0' }, { versionNegotiation: { mode: 'legacy' } });
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const logs: string[] = [];
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client.setNotificationHandler('notifications/message', n => {
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logs.push(String(n.params.data));
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});
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const transport = new StreamableHTTPClientTransport(new URL(url));
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// The mid-stream disconnect surfaces as a transport error before the
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// automatic reconnect; that is the EXPECTED flow, not a failure.
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transport.onerror = () => {};
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await client.connect(transport);
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let lastEventId: string | undefined;
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const result = await client.request(
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{ method: 'tools/call', params: { name: 'long-operation', arguments: {} } },
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{ onresumptiontoken: token => (lastEventId = token) }
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);
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const text = (result as { content?: Array<{ type: string; text?: string }> }).content?.[0]?.text ?? '';
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check.match(text, /completed successfully/);
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check.ok(lastEventId, 'resumption tokens should have been observed');
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// The 75% line is emitted WHILE the client is disconnected; receiving it
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// proves the event store replayed it on reconnect. (Replay ordering relative
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// to the terminal result is not asserted — the result resolving is the
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// signal the disconnect was survived.)
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check.ok(
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logs.some(l => l.includes('75%')),
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`events emitted while disconnected should be replayed (got: ${logs.join(' | ')})`
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);
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await client.close();
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