What is actually goes into each use case activity node? A set path of menu, or the actual end activity?

Question

I'm a complete newbie in UML use case diagram, and trying to grasp the concept of use case. I've just scourging over several videos, tutorials, and examples of UML. But I still have question regarding my case. So for example, I want to create a use case for an app which has menu like this:

• let's say this is an app about social media.
• the app has bottom tab bar with 3 tabs: news feed, community, profile.
• the tab I want to tell the story about is the 2nd tab, "community" tab.
• within community tab, we have another top tab bar with 3 tabs: groups, organisations, contacts.
• let's focus on the 1st tab, "group" tab, which will list the groups.
• when the user tap on the group, it will open a new page, which is the detail of the group, complete with top tab bar: walls, events, members, about.
• let's focus on the the 1st tab, "walls".
• the activity I want to tell in UML use case right now is "user see walls of group".

For this case, which one I should do?

1. do I just create an activity called "see wall", and draw line between user actor to the "see wall",
2. or do I create a set of activities like: user -- see community -- see groups -- see wall?

For the first case, it will be just like actor -- activity. Done. Is this correct? Because my UML use case diagram will be like a list of activities, without connections to others except to the database. If I see other examples, they made it looks like the activity can be extended into several includes or extends. But I feel like I can't includes or extends anymore because the activity I listed is like the most end node only. But to create UML use case like a path of menu isn't feel right either.

Some of my readings:

• https://www.lucidchart.com/pages/uml-use-case-diagram
• https://online.visual-paradigm.com/tutorials/use-case-diagram-tutorial

Answer 1

Use cases are not about functions but about the added value a system under consideration brings to its actors. Once you identified UC and actor you will describe scenarios with Activities inside the UC. Each scenario itself is described by a couple of Actions taken. Alternatively to ADs you can describe a UC with pure text like it's done by Cockburn.

I recommend to read Bittner/Spence about use cases since a detailed description will just take the size of this book.