State and the StreamableHTTP transport

⚙️ Server Flags: Stateless and JSON Response

These flags control how your server handles client connections and data transmission, particularly when scaling.

🌐 Horizontal Scaling Context

• Problem: When a server becomes popular, a single instance cannot handle the traffic.
• Solution: Implement horizontal scaling by running multiple server copies behind a load balancer.
• Challenge: Maintaining client state (e. g. , tracking a continuous connection or multi-step process across different servers) is extremely complex when using a load balancer.

🚩 stateless Flag

Setting this flag to true makes the server unable to track client sessions, which is a trade-off for scalability.

✅ Effects of stateless = true:

• No Session Tracking: The server does not receive or maintain a session ID, meaning it cannot track individual clients.
• Loss of Stateful Features: The server cannot use the gRPC SSE response pathway, limiting features like:
• Sampling
• Progress logging
• Subscriptions
• Efficiency Gain: Eliminates the need for initial client initialization requests, reducing server traffic and complexity.

📦 JSON response Flag

Setting this flag to true changes the format and timing of responses.

✅ Effects of JSON response = true:

• Disables Streaming: POST requests will no longer use Server-Sent Events (SSE).
• Final Result Only: The server waits until the entire tool call or process is complete before sending any response.
• Output: Responses are delivered as plain JSON, without intermediate log statements or streaming updates.

💡 Development Best Practice

• When developing your server locally, always use the transport mechanism (e. g. , HTTP, gRPC) that you plan to use in production to avoid significant issues later.

Takeaways

• Horizontal Scaling: To handle high traffic, servers must use horizontal scaling (multiple instances behind a load balancer), which inherently complicates maintaining client state.
• stateless = true: Setting this flag sacrifices session tracking and all stateful features (e. g. , progress logging, subscriptions) but significantly improves scalability and reduces initial client overhead.
• JSON response = true: This flag disables streaming (SSE) and forces the server to wait until the entire process is complete before sending a single, final response formatted as plain JSON.
• Development Best Practice: Always test your server locally using the exact transport mechanism (HTTP, gRPC, etc. ) intended for production to prevent deployment issues.