topic Re: Spatial attributes to query tasks in Alfresco Archive

Spatial attributes to query tasks

tomvandamme — Wed, 03 Jul 2013 10:20:07 GMT

Hi,I'm looking at Activiti as a candidate BPMN solution. In my use case, all tasks would have a spatial attribute: mostly a point location, but potential more complex geometries like lines or areas. The idea would be that people can search for and subsequently claim tasks that are within a certain d

Re: Spatial attributes to query tasks

frederikherema1 — Wed, 03 Jul 2013 11:47:01 GMT

What you could do (in case of you're plane being a rectangle) is to store the x and y-coordinates separately, so you can use the ProcessInstanceQuery variableValueGreaterThan(String name, Object value); method (and other) to get process-instances which are located in that rectangle.

Other shapes and geometries don't work this way, off course… The variable-query mechanism is quite fixed in activiti, using the available columns in ACT_RU_VARIABLE (TEXT_, LONG_, …) to do simple operators on. If you want to have advanced querying-support on top of the relation DB activiti is using, you're basically on your own.

If you depend on an external system to "index" or "query" the coordinates, than you can keep the task-id and coordinates up to date using activiti-task-listeners and execution-listeners, preventing you to manually keep both sides up to date with new processes…

Re: Spatial attributes to query tasks

tomvandamme — Thu, 04 Jul 2013 06:19:34 GMT

Thanks, I'll try to see how it behaves when putting the co-ordinates in separate long fields. And I'll have to read the listener documentation as well: sounds promising.

Tom

Re: Spatial attributes to query tasks

tomvandamme — Thu, 04 Jul 2013 07:47:34 GMT

Looking further at what we want to achieve, we could also opt to extend activiti's capabilities and introduce support for "geometry" attributes inside activiti. Any idea if there's a chance that this could then make it to the activiti mainline, so we don't need to re-merge our extensions on every activiti release?

Tom

Re: Spatial attributes to query tasks

frederikherema1 — Thu, 04 Jul 2013 08:30:29 GMT

If it's implemented as a "custom variable type" and doesn't require DB-changes, you don't need to merge any code, just plugin your classes into the configuration and it will work on future versions as well.

If it required DB-modification, that's another thing. We only accept "general" features in the engine, so depending on the actual implementation, we can consider adding this. Again, the feature should be "generic" enough, so not sure about the geometry-stuff.