EEB - Early Event Broadcasting
Early Event Broadcasting (EEB) is a facility within z/OS UNIX System Services (USS) that provides a mechanism for processes to broadcast and receive notifications about specific system events. It allows applications to asynchronously subscribe to and be informed of occurrences, such as changes in the hierarchical file system (HFS or zFS), without the need for constant polling. Early Event Broadcasting (EEB) is a feature within IBM MQ for z/OS that enables the immediate publication of critical system events to specific topics. It provides a mechanism for MQ queue managers to broadcast operational status changes and other significant occurrences as soon as they happen, often before full event messages are written to system queues. This allows for near real-time monitoring, automation, and integration with other systems.
Key Characteristics
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- Asynchronous Notification: Events are broadcast and received asynchronously, allowing applications to react to changes without blocking their primary execution flow.
- Part of z/OS UNIX System Services (USS): EEB is an integral component of the USS environment, leveraging its inter-process communication capabilities.
- Event-Driven Architecture Support: It enables the development of event-driven applications on z/OS, where processes can react to external stimuli efficiently.
- Used by System Components: Key z/OS components, such as
BPX.SERVER, utilize EEB to broadcast events related to file system activity or other system-level changes. - Subscription Model: Processes register their interest in specific event types, and the system broadcasts those events only to the subscribed processes.
Use Cases
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- File System Monitoring: Applications can subscribe to events related to file creation, deletion, or modification within HFS or zFS directories, enabling real-time file system surveillance.
- Inter-Process Communication (IPC): EEB can serve as a lightweight IPC mechanism for coordinating activities between different z/OS UNIX processes based on defined events.
- System Management Tools: Tools that need to react immediately to certain system conditions or resource changes can leverage EEB for timely notifications.
- Application Synchronization: Distributed applications running across multiple USS processes can use EEB to synchronize states or trigger actions based on shared events.
Related Concepts
EEB is fundamentally tied to z/OS UNIX System Services (USS), acting as a core facility for event notification within that environment. It complements other Inter-Process Communication (IPC) mechanisms by offering an asynchronous, broadcast-oriented approach. The BPX.SERVER address space is a primary user and broadcaster of events via EEB, particularly for HFS/zFS file system events. It underpins event-driven programming paradigms on z/OS, allowing applications to be more responsive and efficient than traditional polling methods.
- Selective Subscription: Subscribe only to the specific event types and scopes (e.g., particular directories) that your application truly needs to avoid unnecessary event processing overhead.
- Efficient Event Handling: Design event handlers to be lightweight and perform their processing quickly to prevent backlogs or performance degradation for other subscribers.
- Error Handling and Recovery: Implement robust error handling for event reception and processing, including mechanisms for dealing with missed events or temporary service unavailability.
- Resource Management: Ensure proper registration and deregistration of event subscriptions to release system resources when they are no longer needed.
- Understand Event Semantics: Be aware of the exact conditions under which events are broadcast and the information contained within each event to correctly interpret and react to them.