Providers look in so called “Locations” to get the updates for existing tasks, and to discover new tasks. Locations are different and specific for each provider. For SharePoint 2013 as task provider, for example, locations are task lists in different SharePoint sites.
How does the provider know where to look, where to find the task updates for the current user? There is a collection of so called “hints”, which tells to the provider – please go and look there. In the case of SharePoint, there is an event receiver on each tasks list (new “Tasks with timeline”, content type 171), which, whenever a task for a user is added, stores that list in the hints collection. During the provider refresh, SharePoint provider looks for the tasks in that list, and, if found caches the tasks, and the list. In that process, that task list becomes a known “location”, and the tasks for the user that belong to that list are displayed under that “location” in the MyTasks.
There are also tasks without a location, so called “personal tasks”. The “My Tasks” page inside user’s My Site, is meant to be a place where users can organize their personal tasks, which do not belong to any of the tasks lists in the SharePoint Sites, or Projects. Those tasks are stored only in the “WmaAggregatorList_User” list, and, if Exchange Sync is configured, they are pushed to the Exchange, and therefore accessible in Outlook, mobile devices, etc.
All tasks without location can be “promoted” to the location tasks, what means, they can be “pushed” to a SharePoint list or to Project Server. Once when such a task gets a location, and after it is promoted, its location cannot be changed anymore (tasks cannot be moved across the locations).
Now, this was just an introduction to the WMA concepts and lingo. For anyone who wants to know more how WMA works under the hood, there is a great white paper written by Marc Boyer from Microsoft, which covers all installation and configuration aspects of Work Management Service (bit.ly/1ioO2Zz).
Let’s see now, what can be done with WMA from a developers’ perspective.