Skip to main content

Activity Diagrams: Pertaining to the Project

I don't think I'll be posting about every diagram I do--they're not great works of art the world must see, and if you really wanna see them they'll be in the Github repo. But I did want to post something project specific for each piece of theory here. Thus, please see below.



I think this is pretty self explanatory, even to the uninitiated. Black dot with no ring is the start point, black dot with a ring is the end of the use case. In this case, we can end the use case by just...stopping, or by going on to the "create course" use case. Which will be a diagram I can link to, hence that weird symbol after the Create Course block.

As an aside, I'm using a program called Violet to do my diagrams, and have been for about a year now. It may not be as fancy as Visio or several online subscription options, but I'm honestly more interested in being able to get something on paper (so to speak) quickly, so I can start messing with it. I need to understand what I'm looking at, not be wowed by how cool it looks. Plus, the damn thing is free, period, so it's perfect for personal or student use.

Activity diagrams are really simple stuff, and you'll note I pulled the "main" use case (create an account) and didn't dive into the secondary ones (set e-mail, for instance). I feel there's a law of diminishing returns when nesting diagrams like this...and seriously, "set password" is a single method use case (or damn near), as far as what I have to write. I'm not mapping out that flow--that level of detail is where the sequence diagram and the class diagrams come in.

Again, while I'm knee-deep in planning and this is all front of mind, I don't really need a visual reminder of what is going on...but later, with the last use case I work on? Or if I need to go back in and debug something? Might as well just lay this all out, document it, and have it on hand for reference.

Y'know, like blueprints to a skyscraper.
Labels:

Comments

Post a Comment

Popular posts from this blog

Use Cases: The Theory

They told me in my CSCI-1275 Systems Analysis and Design course there's a tendency for programmers to just start coding stuff without thinking, and this was nigh on tantamount to total catastrophe. I didn't fully understand this until a little later in the semester. We had just learned about arrays and collections in my CSCI-1630 C# Programming I course, and I found this to be a perfect excuse to write a little application that would synthetically divide polynomials . (That's a really great way to master synthetic division, actually, if you're interested in brushing up on that skill. Although my wife still insists the time would have been better spent putting more time into my algebra homework. Two types of people...). At any rate, long story short: I made the program work perfectly, for 3rd degree polynomials that divided evenly. Then I realized it broke when I tried a polynomial of the 4th degree. And then again when the 3rd degree polynomial had a remainder. ...
Post a Comment
Read more

Sequence Diagrams: Theorizing

The activity diagram is all well and good, and can even be super useful in a lot of cases. But for my money, so far in my limited experience, the sequence diagram is where you really start to get a handle on what you need to do as a programmer. Before the sequence diagram, you're dealing with steps in a process. What needs to happen, in what order, and you could just as easily be talking about employees or way stations or widgets or nothing at all. They're really about systems analysis--that high level, what needs to happen kind of stuff. Really important work, but totally dull from a programmer standpoint. The sequence diagram is where we start seeing method names and parameters being laid out. The interaction between classes and layers. You start to see what methods you'll need, in what classes, and get a feel for what properties those classes will need. You can see the flow of the data from the start of the operation to the end, note the inputs and the outputs. I...
Post a Comment
Read more

Activity Diagram: Theory

So I've got use cases figured out. Not all of them--only a fool or a genius thinks he can sit at a desk away from the end user and think he's got all the use cases figured out (and a genius would never truly believe it). But you can't sit around trying to anticipate every possible use case before you start, so once we have enough to cobble together a complete program or part of one we can move on for a bit. Side note, this is the beauty of the agile approach: "Yeah, we know we gotta go to the moon. But we have to do it in 10 years, so we can't spend 5 years thinking up every problem we might need to solve before we start solving them. How about we start with 'design a rocket that reaches orbit without killing anyone' and build on that when we finish?" That's called an iteration, but more on that later. Fleshing out what that use case needs is the next step, and there are a couple tools I remember being taught. One of them is the activity diagra...
Post a Comment
Read more