Add SSE polling support (SEP-1699) (#1654)

examples/clients/sse-polling-client/mcp_sse_polling_client/main.py

@@ -0,0 +1,105 @@
+"""
+SSE Polling Demo Client
+
+Demonstrates the client-side auto-reconnect for SSE polling pattern.
+
+This client connects to the SSE Polling Demo server and calls process_batch,
+which triggers periodic server-side stream closes. The client automatically
+reconnects using Last-Event-ID and resumes receiving messages.
+
+Run with:
+    # First start the server:
+    uv run mcp-sse-polling-demo --port 3000
+
+    # Then run this client:
+    uv run mcp-sse-polling-client --url http://localhost:3000/mcp
+"""
+
+import asyncio
+import logging
+
+import click
+from mcp import ClientSession
+from mcp.client.streamable_http import streamablehttp_client
+
+logger = logging.getLogger(__name__)
+
+
+async def run_demo(url: str, items: int, checkpoint_every: int) -> None:
+    """Run the SSE polling demo."""
+    print(f"\n{'=' * 60}")
+    print("SSE Polling Demo Client")
+    print(f"{'=' * 60}")
+    print(f"Server URL: {url}")
+    print(f"Processing {items} items with checkpoints every {checkpoint_every}")
+    print(f"{'=' * 60}\n")
+
+    async with streamablehttp_client(url) as (read_stream, write_stream, _):
+        async with ClientSession(read_stream, write_stream) as session:
+            # Initialize the connection
+            print("Initializing connection...")
+            await session.initialize()
+            print("Connected!\n")
+
+            # List available tools
+            tools = await session.list_tools()
+            print(f"Available tools: {[t.name for t in tools.tools]}\n")
+
+            # Call the process_batch tool
+            print(f"Calling process_batch(items={items}, checkpoint_every={checkpoint_every})...\n")
+            print("-" * 40)
+
+            result = await session.call_tool(
+                "process_batch",
+                {
+                    "items": items,
+                    "checkpoint_every": checkpoint_every,
+                },
+            )
+
+            print("-" * 40)
+            if result.content:
+                content = result.content[0]
+                text = getattr(content, "text", str(content))
+                print(f"\nResult: {text}")
+            else:
+                print("\nResult: No content")
+            print(f"{'=' * 60}\n")
+
+
+@click.command()
+@click.option(
+    "--url",
+    default="http://localhost:3000/mcp",
+    help="Server URL",
+)
+@click.option(
+    "--items",
+    default=10,
+    help="Number of items to process",
+)
+@click.option(
+    "--checkpoint-every",
+    default=3,
+    help="Checkpoint interval",
+)
+@click.option(
+    "--log-level",
+    default="INFO",
+    help="Logging level",
+)
+def main(url: str, items: int, checkpoint_every: int, log_level: str) -> None:
+    """Run the SSE Polling Demo client."""
+    logging.basicConfig(
+        level=getattr(logging, log_level.upper()),
+        format="%(asctime)s - %(name)s - %(levelname)s - %(message)s",
+    )
+    # Suppress noisy HTTP client logging
+    logging.getLogger("httpx").setLevel(logging.WARNING)
+    logging.getLogger("httpcore").setLevel(logging.WARNING)
+
+    asyncio.run(run_demo(url, items, checkpoint_every))
+
+
+if __name__ == "__main__":
+    main()