Have you ever actually used a use case diagram?

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20 Replies - 5285 Views - Last Post: 24 April 2014 - 11:28 PM

#16 salindor  Icon User is offline

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Re: Have you ever actually used a use case diagram?

Posted 14 October 2009 - 05:20 AM

I didn't learn use cases or uml diagrams in school. I didn't take that class and it wasn't required. In school I focused more on how to program and program well. Then I found that when I had a complicated program I would invariably create a drawling of the inner workings to help me sort out how it was built. Followed by building something similar to what I drew ( the drawing was only a guide not a rule). I later learned, it wasn't that much of a stretch to turn my powerpoint diagrams which were only meant for me; into uml and now they become an artifact of the project. Someone who has never seen my code before can look at my uml and get the general flow characteristics of my program. So basically I have a love/hate relationship with uml. I hate it, and I love it. But I wish back in school I had slipped a class in about it.
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#17 CBart21  Icon User is offline

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Re: Have you ever actually used a use case diagram?

Posted 14 October 2009 - 02:50 PM

USE CASES:

These are just another tool to use if you get stuck trying to figure out how your program should work and how to design it so all the modules fit together. When you are dealing with a more and more complex program, use cases can be used to direct your thinking from top down to bottom up, which is a very important paradigm shift.

No one doubts that putting in some thought in order to design complex program is anything short of necessary. However, like I said, it's just ONE tool you should include in your toolbox when you need it.

Let's assume you are creating a 2D computer game in OpenGL and C++ like I did a few days ago for my OpenGL programming class. Instead of hacking out the code for the program, I decided I would get it done much quicker by thinking about how I wanted to put everything together. I know I had to create the logic for the collision detection, mouse click selection, score and level functionality, etc.

Starting from top-down, I discovered how each subsystem should work together. At a lower level, I decided how each class should fit together. Now, in order to design how each class works, I needed to find out what each class does. I do this using USE CASES. I don't really make the diagram, but I decide what each classes functionality is. Each function of the class immediately becomes the name for a class method. Then, I go back to my top-down approach and decided how each method works, from there I go back to bottom up and decide what private class variables.

In this way it's VERY important going from top-down to bottom-up and back again in order to get a decent design. The diagrams are not really that important, but supposedly it is important if you have a customer so they can see what the functionality of the program is supposed to do in plain English.


I hope that helps,


Chris B
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#18 ecuscotty  Icon User is offline

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Re: Have you ever actually used a use case diagram?

Posted 21 October 2009 - 07:30 AM

I have found a Use Case diagram to be an essential part of any project of which I am a part. They are priceless when it comes to separating out the functionality of a system and make communicating the system to a client very easy. If the use case is well written then even the least technical client can look at it and know what the system is supposed to do. Its all about communication.
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#19 janotte  Icon User is offline

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Re: Have you ever actually used a use case diagram?

Posted 24 April 2014 - 07:46 PM

First thing to acknowledge is most Use Case diagrams I have ever seen are appalling bad and worse than useless.

But one thing I can get out of one of the rare good ones is the list of actors able to undertake a given use case. This can help a lot in identifying the access privileges required by a given actor. If I can search through the Use Cases for the string "Contributor" and see all the Use Cases that actor needs to have access to then I am able to map out the privileges for that user.

Not sure that that 'win' is worth the huge costs of preparing the diagrams but it is one the things of value I do get out of them when they are done well.
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#20 depricated  Icon User is offline

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Re: Have you ever actually used a use case diagram?

Posted 24 April 2014 - 09:19 PM

I work on an enterprise SaaS, on a team of about 60 devs. Our testers use Use Case diagrams to plot out manual testing that needs to be done to verify requirements. We as devs don't touch them very often. Usually I get a defect that reads something like "print options reset after answering questions" but it leaves out critical things like the fact that the questions are on a different page.
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#21 Parrish  Icon User is offline

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Re: Have you ever actually used a use case diagram?

Posted 24 April 2014 - 11:28 PM

I think UCs help explain functionality. Although I haven't used them outside of course yet. It was a nice point when trying to figure something out, provided the UCs are done before the system is developed.
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