Adding a Data Event Handler and Publisher

A data event handler represents an interface in ONE MDM that captures changes in entity attributes during data processing and forwards change events to external systems using various connection channels.

Change events (that is, changes in record data) always originate from a load operation (either streaming, a batch load, or service processing request). These events can be transformed and published with current attribute values and old attribute values (filtering rules can be applied to some extent).

Change events originate from monitored entities across all MDM model layers.

What are event handlers used for

Event handlers enable real-time or near-real-time data synchronization between ONE MDM and downstream systems. Common use cases include:

Data distribution: Propagating master data changes to consuming applications (CRM, ERP, data warehouses).
Event-driven workflows: Triggering business processes in external systems when specific data changes occur.
Audit and compliance: Maintaining a record of data changes for regulatory or historical purposes.
System integration: Keeping multiple systems synchronized as data evolves.
Analytics and reporting: Streaming data changes to analytics platforms for real-time insights.

Event handlers allow you to filter which changes are captured (by entity, attribute, operation type, or custom expressions) and define how those changes are transformed and delivered to target systems.

How event handlers work

Regardless of the handler type, the basic workflow is:

Capture: During processing, the handler captures change events based on configured filters.
Store: Events are temporarily persisted to storage (database and/or file, depending on the event handler type).
Process: Once the operation completes, the handler processes the captured events.
Publish: Processed events are distributed to external systems via configured publishers.

Event handler types

ONE MDM provides two types of event handlers.

Streaming Event Handler

The Streaming Event Handler (EventHandlerStreaming) is a high-performance, unified implementation designed for optimal throughput and simplified configuration. It is recommended for all new implementations.

The handler offers unified processing with built-in traversing, batching, and grouping capabilities. Events can be persisted in a database only.

For configuration instructions, see Streaming Event Handler.

Async Event Handler

The Async Event Handler (EventHandlerAsync) is the legacy implementation that will be deprecated in version 17 and removed in version 18.

If migration is not immediately possible, the Async Event Handler can continue to be used for small data volumes until version 18. It is used for existing implementations and small data volumes until migration is complete.

The handler consists of two independent parts:

Processors: Control how events are consumed (Batching, Simple, or Grouping).
Publishers: Define how events are distributed to external systems (SQL, SOAP, JMS, Plan).

Different processors and publishers can be combined; see Processor and publisher combinations for details.

Events can be persisted in a file or database.

Configuring event handlers

Depending on the event handler you’re using:

Streaming Event Handler: Configure the handler according to Streaming Event Handler.
Async Event Handler: For reference configuration, see Processors and Publishers.

We strongly recommend migrating to the Streaming Event Handler at your earliest convenience. For migration guidance, see Migrating to Streaming Event Handler.

Monitoring event handlers

For information about monitoring event handlers, see MDM Web App Admin Center > Event Handlers.

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