Client Identification

AMPS uses the name of the client as a session identifier and as part of the identifier for messages originating from that client.

For this reason, when a transaction log is enabled in the AMPS instance (that is, when the instance is recording a sequence of publishes and attempting to eliminate duplicate publishes), an AMPS instance will only allow one application with a given client name to connect to the instance.

When a transaction log is present, AMPS requires the client name for a publisher to be:

• Unique within a set of replicated AMPS instances

• Consistent from invocation to invocation if the publisher will be publishing the same logical stream of messages

If publishers do not meet this contract (for example, if the publisher changes its name and publishes the same messages, or if a different publisher uses the same session name), message loss or duplication can happen.

60East recommends always using consistent, unique client names. For example, the client name could be formed by combining the application name, an identifier for the host system, and the ID of the user running the application. A strategy like this provides a name that will be different for different users or on different systems, but consistent for instances of the application that should be treated as equivalent to the AMPS system.

Likewise, if a publisher is sending a completely independent stream of messages (for example, a microservice that sends a different, unrelated sequence of messages each time it connects to AMPS), there is no need for a publisher to retain the same name each time it starts. However, if a publisher is resuming a stream of messages (as in the case when using a file-backed publish store), that publisher must use the same client name, since the publisher is resuming the session.