Hi all,
I'd like to propose PIP-482, which adds a messagePosition parameter to the
Java admin client's Topics.peekMessages and peekMessagesAsync methods.
The underlying REST endpoint:
/admin/v3/persistent/{tenant}/{namespace}/{topic}/subscription/{subName}/position/{N}
already accepts an arbitrary message position. The current Java admin
client hardcodes 1, so callers can only peek from the head of the backlog.
The most common use case affected is paginated display in admin UIs. To
show the 91st–100th unacknowledged messages, callers currently have to
fetch and discard the first 90.
This PIP surfaces the existing server capability at the Java client level.
API surface (summary)
The new primary abstract method:
List<Message<byte[]>> peekMessages(
String topic,
String subName,
int messagePosition,
int numMessages,
boolean showServerMarker,
TransactionIsolationLevel transactionIsolationLevel)
throws PulsarAdminException;
All pre-existing peekMessages overloads become default methods that
delegate to this primary method, giving the interface a single source of
Javadoc.
Compatibility
This change is source- and behavior-compatible for all existing call sites.
The pre-existing 5-argument abstract peekMessages(..., numMessages,
showServerMarker, isolation) method becomes a default method, which is
binary-compatible according to the Java Language Specification.
References
Pull request:
https://github.com/apache/pulsar/pull/25911
PIP markdown:
https://github.com/Pruthvirajj240/pulsar/blob/pip-482-peek-messageposition/pip/pip-482.md
Looking forward to feedback on the API shape, parameter naming, and
backward-compatibility approach.
Thanks,
Pruthviraj
