Market Participants receive information from MISO through two primary communication methods:
1) Request/Response (Pull) Messages via API GET/POST Requests
2) Push Notifications (Asynchronous Messaging)
Request/Response Communications (Pull Method)
Market Participants receive data from MISO by issues GET/POST requests to MUI 2.0 API endpoints. GET requests are subject to polling rate limits. If participants exceed the limit, MISO returns HTTP 429 Too Many Requests and clients must self-throttle. Refer to MISO MUI API Guide for polling rate limits.
Rate Limit details:
- Default GET rate limit is 100 ms per endpoint
- Some endpoints have higher limits (up to 300,000 ms)
- Invalid requests count toward limit rates
- Rate limits apply per user certificate and per asset owner
Push Notifications (Asynchronous Messaging)
MISO sends real-time, unsolicited messages to participant listener URLs. Participants must maintain an active HTTPS listener and acknowledge receipt with HTTP 200 OK.
MISO does not retry failed notifications.
Summary of Communication Methods
| Method | Initiator | Behavior | Purpose | Notes |
| GET/POST Request- Response | Participant | Synchronous | Retrieve market data | GET requests have polling rate limits |
| Push Notifications | MISO | Asynchronous | Receive instructions and alerts | Participant must maintain listener; re retries sent |