Infor M3 API Toolkit: A Developer's Guide to MI Programs and MvxAPI
The Infor M3 API toolkit is the backbone of every custom integration, third-party connector, and automation workflow in an M3 environment. Whether you are calling MI programs like MMS200MI for item creation or OIS100MI for order entry, understanding the transaction model, field mapping, and error handling patterns is essential. This guide covers the practical development patterns that M3 consultants and architects rely on daily.
Understanding MI Programs and Transaction APIs
M3 exposes business logic through MI (M3 API) programs, each corresponding to a core function. MMS200MI handles item master operations, OIS100MI manages customer order entry, and CRS610MI controls customer master maintenance. Every MI transaction follows a request-response pattern with defined input/output fields, validation rules, and commit semantics that developers must honor to avoid data corruption.
- MMS200MI: AddItem, UpdItem, GetItem for item master CRUD with warehouse-level defaults
- OIS100MI: AddBatchHead, AddBatchLine for batch order creation with price simulation
- CRS610MI: Add, Update, Get for customer master with address and financial data
- MvxAPI class provides connection pooling, session reuse, and timeout configuration
- Each MI call returns a MIResponse with status codes and field-level error messages
Authentication, Session Management, and Error Handling
Production M3 API integrations demand robust session management. The MvxAPI session pool must handle concurrent requests without exhausting M3 jobs. Connection pooling, retry logic with exponential backoff, and proper session teardown prevent the job queue saturation issues that cripple many M3 environments under load.
- Configure MvxAPI connection pool size to match M3 job server capacity (typically 10-25 sessions)
- Implement exponential backoff retry with jitter for transient NOK responses
- Parse MIResponse.ErrorCode and ErrorField for granular error routing to calling systems
- Use IonAPI gateway tokens for OAuth2-based authentication in cloud M3 deployments
- Log full request/response payloads at DEBUG level for production troubleshooting
Performance Optimization and Batch Processing Patterns
High-volume integrations processing thousands of transactions per hour require batch-oriented patterns. The M3 API supports batch MI calls that group multiple operations into a single server round-trip, reducing network overhead by 60-80%. Combined with asynchronous processing queues, these patterns enable throughput rates of 5,000+ transactions per hour on standard M3 infrastructure.
- Batch MI calls reduce round-trip overhead from 50-100ms to 5-10ms per transaction
- Use asynchronous ION message queues to decouple sender throughput from M3 processing
- Monitor M3 job server utilization via MNS920 to prevent API-driven resource exhaustion
- Implement circuit breaker patterns to protect M3 during upstream system spikes
- Cache CRS610MI and MMS005MI reference data locally with 15-minute TTL for read-heavy flows
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