Event Manager Architecture

A publish – subscribe or pubsub architecture is used to facilitate notification of events. A client subscribes to an event or range of events either directly, or using an exit provided within the seepubsub utility (described further in this documentation Event Manager - SEEPubSub Client). As the events occur they are pushed to the client side for consumption.

The client connects to the region through a listener using the Micro Focus BINP protocol on a pre-configured port.

Once connected, the subscription request is sent to the region, and an acknowledgement that the subscription was successful is sent back.

A subscription can be either durable or non-durable.

A durable subscription will persist even if the connection to the region is lost. If the connection is lost, all events subscribed will be stored into the database for subsequent retrieval. If the connection is reestablished, the stored events will be pushed to the client. A durable client can even be stopped and restarted without losing events, if it uses the same subscription identifier when it re-subscribes.

There are two types of durability:

• If a subscription is not configured as durable and the client process is running, and the network connection to the listener fails and later corrects whilst the client is running, the running client can re-subscribe and get the missing events.
• If the subscription is configured as durable and the client process is terminated, the client can reconnect with the same subscription details, and the events will resume from where they left off.

The seepubsub utility is provided with theEnterprise Server for .NET distribution. It can be configured to subscribe to multiple events within multiple regions, and then feed those events to a user exit (a user program written to handle the events) per subscription.

A user program can also subscribe directly to events. A simple example called "subscribe" demonstrating this is included in the samples provided with the product. Please use the samples browser to locate the example.