Last week we started on use case modeling and how the event table assist in designing use case diagram. We touched on the rules, the diagrams and the way to interpret the use case models. The use case diagram puts how words in the event table into a diagram to see the system and how actors or users interact with the system.
After a thorough walkthrough of the use case diagram, we went on to activity diagram and the class diagram. In the class diagram, we discuss how objects in the system gets created and how they interact with each other. Also what are the attributes and function the object has.
After confusing us with so many diagrams, Rob threw in another diagram; sequence diagram. ARGHZ!!! Well... The sequence diagrams shows how a use case goes through all the functions till it ends. It mimics almost like the activity diagram but it shows how the objects interact with each other.
All in all, the diagrams go through a flow. We start off with the events table. After stating all the possible events we move on to drawing the use case diagram. The use case diagram now shows the functions of the system and the boundary of where the user stands against the system. From the use case diagram, we design the class diagram so as to design the database. This would be objects that will be in or out of the system. Lastly, we draw the sequence diagram to explain further or more in-depth.
Sometimes we take a step back to the previous diagram to cross-reference it. It ties up the loose ends of the system and makes it more robust. I guess its how this diagrams comes together in relation and how we use them to design successful systems. Even though more than 50% of systems fail. :D
Subscribe to:
Post Comments (Atom)
3 comments:
I don't know about that 50% statistic! Do you have a source you can cite for that!?
Cheers,
Rob.
A quick google search turns up an article that cites a failure rate of about 35% (although only 15% of systems were a 'full' success - ie. the rest compromised on requirements to some extent).
See http://www.it-innovations.ae/iit005/proceedings/articles/I_5_IIT05_Nauman.pdf
I did read it up somewhere before. But i had sources that the numbers are usually sourced from another, the another and another. At the end, i do wonder who or what source can we trust.
Especially when the internet has so much information we cannot trust.
Post a Comment