REST API tasks and activities

[Marcin]

Hello,

I have a question regarding tasks and activities available for REST API.

First of all is the list of the tasks some how predefined? I have find out that for each newly created project GET /projects returns json document with following list of tasks: dataset, transform, linking, workflow defined for each project.
Is this list of task fixed or I can somehow create my own tasks?

The same applies to activities. Is the list of activities predefined and is it possible to define own activities? I can't find any way to list all available activities. Is it possible to do that using REST API? If not, what are the available activities?

Best,
Marcin