Message fabric overview

The message fabric is a messaging infrastructure that connects the system components and allows them to communicate.

Messages are transmitted to the components over the message fabric. The message fabric constitutes the message queues to write and retrieve application-specific data to and from the queues without the requirement for a private, dedicated connection to link the components.

WebSphere® MQ is used for messaging in production installations of AS4 Microservice. In stand-alone installations that are used for proof-of-concept and demonstration purposes, WebSphere eXtreme Scale is used for messaging. For more information about WebSphere MQ, see WebSphere MQ and AS4 Microservice.

Message queues are used to configure messaging receivers and messaging destinations. In AS4 Microservice, messaging destination and messaging receiver are used to send and receive the business document object, payload, and attachments from the business application. Additionally, message queues are used when configuring the notification destination to notify the business application of any errors. Default error notification queues are created during the deployment of AS4 Microservice. However, you can also create custom notification queues based on your requirements.

Note: If the communications component receives a notification (critical event) about low grid memory, the messaging receivers stop accepting the incoming messages for processing. The messages that are already accepted are processed. After the memory clears and raises above the low watermark, another notification is sent to the communications component. Thereafter, the messaging receivers start accepting the messages.