Using Message Exchange and Attributes

References allow identification and communication between objects in the ArchestrA environment. Every object, every attribute, and every property can be uniquely referenced. Those references are communicated over the messaging system. The Message Exchange is the object-to-object communications protocol used by ArchestrA and the Application Server.

Note: ArchestrA is the framework for supervisory control and manufacturing information systems. It is an open and extensible technology based on a distributed, object-based design. For example, if you are using Application Server with InTouch, these products communicate with each other using the ArchestrA framework.

All object attributes have properties, such as Value and Quality. Any data read or written to or from these attributes over ArchestrA Message Exchange is tracked. If an operation cannot be performed, the requesting client is notified.

Message Exchange provides the following features and information:

• Guaranteed response

• Name signatures

• Status and data quality

• Message order preservation within a priority system

• AppEngine-to-AppEngine buffering

• Publish-subscribe heartbeats