[
https://issues.apache.org/jira/browse/SLING-6745?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15949040#comment-15949040
]
Stefan Egli commented on SLING-6745:
------------------------------------
[~ianeboston], the MoM-based Job API has definitely been considered, as a kafka
variant based on that is pretty straight-forward. However there's the
backwards-compatibility argument that came up: there are many existing users of
the Sling Event based Job API which would have to be ported to the Mom-based
Job API - and the aim is to avoid requiring user adjuments as well as having 2
different APIs in the same deployment.
This is why the suggestion was with SLING-6739 to split sling.event into
sling.event.api and sling.event.resource (in a way that users of the API
wouldn't notice anything, ie code compatible). This would then open the way for
other implementations of sling.event.api - such as this kafka variant.
Now with regards to this new kafka-based implementation and the MoM-based API &
implementation I see the following different variants:
# A bridge implementation could map sling.event.api to
[sling.job|https://github.com/apache/sling/tree/trunk/contrib/commons/mom/jobs/core]
and fill in the gaps. One such gap is as mentioned the support for querying
for jobs - which is what you also pointed out. That could be added to this
bridge. The implementation of the kafka part would then be based on the
sling.mom SPI.
# An implementation that uses the [MoM
API|https://github.com/apache/sling/tree/trunk/contrib/commons/mom/api] for the
messaging part, but doesn't use the [MoM-based Sling Jobs
API|https://github.com/apache/sling/tree/trunk/contrib/commons/mom/jobs/core]).
Additionally it would add the job query part, same as above.
# just reuse (ie copy + modify) code from the MoM-based implementation (not the
API) and marry that with the job query part. Then implement everything for
Kafka.
# same as 3. but define a different MoM API.
I'm not sure yet which is the best option, but 1) a mix of sling.event.api and
sling.job API (the
[org.apache.sling.jobs|https://github.com/apache/sling/tree/trunk/contrib/commons/mom/jobs/core/src/main/java/org/apache/sling/jobs]
package) seems less favorable to me. Whether 2. is possible needs to be seen.
As a summary : I think it doesn't make sense to reuse the [MoM-based Jobs
API|https://github.com/apache/sling/tree/trunk/contrib/commons/mom/jobs/core] -
but it might make sense to use the [MoM
API/SPI|https://github.com/apache/sling/tree/trunk/contrib/commons/mom/api].
Wdyt?
> kafka-based sling.event.api implementation
> ------------------------------------------
>
> Key: SLING-6745
> URL: https://issues.apache.org/jira/browse/SLING-6745
> Project: Sling
> Issue Type: New Feature
> Reporter: Stefan Egli
> Assignee: Stefan Egli
>
> In job handling to scale for larger deployment it is essential to be able to
> execute a job outside of the local instance. This can be in another instance
> in the same cluster (ie when ontop of documentMk) or outside of the cluster
> (in AEM eg via
> [offloading|https://docs.adobe.com/docs/en/aem/6-2/deploy/configuring/offloading.html]).
> In both cases Sling Event (Resource) stores the job in the repository
> (/var/eventing/jobs).
> It could be useful to have another variant of job execution that is managed
> entirely outside of the repository. With SLING-5645 a new API was created to
> support messaging-based implementations that would fit in this category as
> they map a job to a (one or a few) message(s).
> This new SLING-5645 Job-API is not entirely compatible with sling.event.api
> though.
> This ticket is to track an effort to provide a messaging-based implementation
> for sling.event.api - namely for Kafka. The goal is to become a drop-in
> replacement of sling event without much need for change on the user side of
> the sling.event.api.
> This might not right away become part of sling, but might start off in the
> contrib section - to underscore that it's not something supported, at least
> as of yet.
--
This message was sent by Atlassian JIRA
(v6.3.15#6346)
