We are integrating our portal P with another third party web application W. The W will be displayed in our portal inside a modal popup.
One of the obvious user stories (let's call it US1)
As a user U when click a button B, W should be displayed as a popup and the certain information set 'IS' should be pre-populated so that I can review the information set 'IS'.
Now to pre-populate information set IS, we'll need to create a set of APIs and integrate at the back-end to send the information from our portal P to the web application W.
The question I have is, should the creation of the API be a system user story or a task?
The work can be done in a sprint but the API creation and integration will probably me multiple tasks. Also completion of this integration blocks the subsequent user stories in the third party web application.
So should I write a system user story (lets call it SUS1) and tasks like so ?
As a portal P I should be able to send information set IS to third party web application W so that the user U can view this information.
This will obviously require creation of sub task T such as
"Create API A"
Or should I just create a sub task T for the user story US1.
The team here is more comfortable with calling everything stories so that they can easily view their activity in the sprint burn down and especially communicate and show that subsequent user story US2 is dependent on system user story SUS1.
User stories are written from the point of view of end users and describe what it is they want to get from the product. They do not describe how the implementation will be done.
What you have described is not a user story, instead it is a combination of several implementation tasks.
An example of a user story might be:
As a portal user I want to see today's weather information so that I can know what the weather will be like today
Once this user story is assigned to a sprint the development team may well break it down in to a number of technical tasks. This would include the creation of an API sufficient to deliver the user story.