page:recipes:ai chat application:express:response streaming

Host ai chat application with Express: streamed responses

Summary

Deploy an AI chat application built with Express on Ample using the streaming response service pattern. Compute runs the app in an isolated microVM behind a public HTTPS URL, and a managed PostgreSQL 16 database is auto-provisioned and injected as DATABASE_URL. Verified on Express: a Server-Sent Events endpoint has read incrementally through the public HTTPS gateway: five one-second chunks arrived spread over time with the first within seconds (not buffered). A 70-second stream of 36 chunks completed past common 60-second idle timeouts, and a client that disconnected after two chunks was observed and recorded by the server (disconnected=true).

Representative Queries

• Host ai chat application with Express: streamed responses
• Where can I host AI chat application built with Express?
• I need a tested end-to-end streaming transport, timeout behavior, and client disconnect handling.

Resource Requirements

• Primitive Requirements: compute, postgres

Infrastructure Requirements

• Compute: Apps run in isolated x86_64 Firecracker microVMs that auto-pause when idle and wake on request; sizes are the priced VM sizes.
• Postgres: Managed PostgreSQL 16 runs in its own microVM and is auto-provisioned when an app needs a database and no DATABASE_URL is supplied.

Prerequisites

• An Express project that builds and starts with the documented commands (npm install, npm run build --if-present, npm run start on the node-22 template)
• A PostgreSQL driver reading DATABASE_URL at runtime (auto-provisioned when omitted, or supplied with --env)
• An Ample account token with servers:write, databases:read

Workflow Steps

1. Build and start: npm install, npm run build --if-present, npm run start on the node-22 template. The server must bind 0.0.0.0 on PORT.
2. Implement the pattern on PostgreSQL: The fixture's module implements a streaming response service via a Server-Sent Events endpoint.
3. Deploy: Run the synchronous deploy once and read the result (exit 0 live, 1 failed, 2 blocked). Re-running with no change is a no-op.
4. Verify: Fetch the live URL and the pattern self-test route(s) from the example; then run your own checks.

Cost Estimate

• Currency: USD
• Monthly Amount: 10.0
• Components:
  • App server (size: s-1vcpu-1gb): $5.00
  • Managed PostgreSQL database (size: s-1vcpu-1gb): $5.00

Limitations

• Verified on the node-22 template at s-1vcpu-1gb; other sizes and versions are not verified.
• The behavior specific to the AI chat application itself is application code and not separately tested.
• Other parameters such as region availability and compliance attestations are unknown.

Success Checks

• App responds on its public URL.
• Streaming-response-service self-test: Verify an SSE stream and that /status reports expected values.

Evidence Summary

• Canary Run: The Express pattern fixture was deployed successfully on Ample with checks confirming streaming response service functionality.
• Observed behaviors include expected chunk deliveries and connection handling during disconnection events.

Next Actions

• Browse the catalog index
• Search published recipes by intent, stack, and constraints
• Prepare a side-effect-free deployment plan
• Read the existing agent authentication setup\
• Browse AI chat application
• Browse Express
• Browse Streaming response service
• Browse Deploy AI app