Cloud Workflow - PATCH method call within Service Task issue

[RoryA]

When attempting to call the PATCH method within a service task, I get a 503 - Service Unavailable" but have no issue calling it from Postman. Not sure if its a XSRF issue or not but Im doing a GET call to the same URL just prior that is successful, hoping that it loads the XSRF token. Looking for a solution.

Thanks

Rory

[tobias_breyer · Accepted solution]

Hi Rory,

there are several possible reasons for the issue.

1) You might be doing lots of concurrent changes and running into certain operational limits of the service. This is especially the case if you call from within a workflow instance into workflow REST APIs, as you use at least one database connection for the service task and one for the REST API. Then doing some more concurrent calls and you are near the limits.

2) You might be trying to change the same workflow instance via REST API in which you currently also execute the service task. This does not work in all the cases and is discouraged. Please refer to note 2884301

The note is a bit outdated. When using model changes as a solution, there have been several enhancements that are not yet mentioned there. For example, you could use the Subflow feature which technically is a separate workflow instance but referenced from the parent. The lifecycle of the two workflow instances is largely decoupled, so this can help here, together e. g. with terminating end events or canceling timer boundary events.

Additionally, do not use the HTML5 / FLP domain for Workflow REST calls. In such technical scenarios, you just add another unnecessary layer, so increasing latency and complexity. On Neo, for REST API calls, you should usually use the domains of the pattern bpmworkflowruntime<provider-account>-<subscribed-account>.<region>.hana.ondemand.com

Regards,

Tobias