sample: Add a sample using a group of MCP clients.

src/examples/client/clientGroupSample.ts

@@ -0,0 +1,129 @@
+import { Tool } from "../../types.js";
+import { Client } from "../../client/index.js";
+import { InMemoryTransport } from "../../inMemory.js";
+import { McpServer, ToolCallback } from "../../server/mcp.js";
+import { Transport } from "../../shared/transport.js";
+
+async function main(): Promise<void> {
+  console.log("MCP Client Group Example");
+  console.log("============================");
+
+  const clientTransports = await spinUpServers();
+
+  const client1 = new Client({
+    name: "client-1",
+    version: "1.0.0",
+  });
+  client1.connect(clientTransports[0]);
+
+  const client2 = new Client({
+    name: "client-2",
+    version: "1.0.0",
+  });
+  client2.connect(clientTransports[1]);
+
+  const client3 = new Client({
+    name: "client-3",
+    version: "1.0.0",
+  });
+  client3.connect(clientTransports[2]);
+
+  const allClients = [client1, client2, client3];
+  const toolToClient: { [key: string]: Client } = {};
+  const allTools = [];
+
+  for (const client of allClients) {
+    for (const tool of (await client.listTools()).tools) {
+      if (toolToClient[tool.name]) {
+        console.warn(
+          `Tool name: ${tool.name} is available on multiple servers, picking an arbitrary one`,
+        );
+      }
+      toolToClient[tool.name] = client;
+      allTools.push(tool);
+    }
+  }
+
+  const allResources = [];
+  allResources.push(...(await client1.listResources()).resources);
+  allResources.push(...(await client2.listResources()).resources);
+  allResources.push(...(await client3.listResources()).resources);
+
+  const toolName = simulatePromptModel(allTools);
+
+  console.log(`Invoking tool: ${toolName}`);
+  const toolResult = await toolToClient[toolName].callTool({
+    name: toolName,
+  });
+
+  console.log(toolResult);
+
+  for (const client of allClients) {
+    await client.close();
+  }
+}
+
+// Start the example
+main().catch((error: unknown) => {
+  console.error("Error running MCP Client Group example:", error);
+  process.exit(1);
+});
+
+async function spinUpServer(
+  name: string,
+  cb: ToolCallback,
+): Promise<Transport> {
+  const server = new McpServer({
+    name: name,
+    version: "1.0.0",
+  });
+
+  server.tool(name, cb);
+
+  server.resource("greeting", "greeting://hello", async (uri) => ({
+    contents: [
+      {
+        uri: uri.href,
+        text: `Hello from ${name}!`,
+      },
+    ],
+  }));
+
+  const transports = InMemoryTransport.createLinkedPair();
+  await server.connect(transports[0]);
+
+  return transports[1];
+}
+
+async function spinUpServers(): Promise<Transport[]> {
+  const clientTransports = [];
+  clientTransports.push(
+    await spinUpServer("ping", async () => ({
+      content: [{ type: "text", text: "pong" }],
+    })),
+  );
+
+  clientTransports.push(
+    await spinUpServer("pong", async () => ({
+      content: [{ type: "text", text: "ping" }],
+    })),
+  );
+
+  // We deliberately spin up 2 servers with the same tool name to
+  // demonstrate dealing with that edge case in the sample.
+  clientTransports.push(
+    await spinUpServer("ping", async () => ({
+      content: [{ type: "text", text: "pong2" }],
+    })),
+  );
+
+  return clientTransports;
+}
+
+function simulatePromptModel(tools: Tool[]): string {
+  console.log(`Model was prompted with the following tools:`);
+  for (const tool of tools) {
+    console.log(`  - ${tool.name}`);
+  }
+  return "ping";
+}