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Looking for a bit of a steer on "how things are done" with regards to defining requirements for a software based project.
I'm fully up to speed with what goes into a requirements catalogue and how useful UML modelling can be.
My question, how are the two linked? Should you write out requirements into the catalogue for any requirements you model using UML - essentially duplicating requirements?
For example,
- A user wishes to source a "product" from a supplier
- To do this they will enter their product details into a "breifing" form
- In this scenario I'd look to use a class diagram to list out all the "briefing" fields (shown on the briefing form) against a "product" class
But, how do I tie those requirements back to the requirements catalogue? If they're not referenced there how will a developer know those requirements exist?
Any help greatly appreciated!
Thanks,
Dan
You should use an Use Cases diagram to make the bridge between requirements and UML.
You could then explicit relationships between your classes and each use case.
A developer can see a particular class is linked to one or many use cases (requirement).
Some modeling tools allo wto include requirements into your UML model. Then you have an explicit link.
For example: http://www.sparxsystems.com.au/downloads/whitepapers/Requirements_Management_in_Enterprise_Architect.pdf (see p. 16)
Otherwise you may export your diagrams and include them into your catalogue document.
Forming the requirements catalogue and having elicited and analysed your audiences requirements up to the point of formal signoff, based on the needs of a project you UML diagrams would normally make reference to a working of functionality or a process which you captured, process workflows/activity diagrams are sound for stakeholders to visualise how there internal processes work, use cases, class diagrams, sequence diagrams etc are more useful for development and QA teams during the design/development phases for devs and qa's.
For each requirement just make reference to the UML diagrams through the use of the requirements ID. But as mentioned earlier, ensure you have traceability between requirements and UML and vice versa,
Hope this helps
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I've been reading Eric Evan's DDD book and I got a bit confused. Maybe I'm too pedant, but I want clarity in things I deem important.
Eric states that when doing DDD we should first create a model. And based on the model we should create the design. Why? Shouldn't the design come first and then the model? Since first we have to design something "make a plan, or a drawing or diagrams", then model it "maybe add more diagrams or software artifacts with more details" that eventually we will implement in code.
What am I missing?
I've been investigating the words lately to understand precisely what they mean, because I understood that I devised some incorrect conclusions or even misinterpreted some terms, which is quite dangerous.
In my understanding in the real world. Design comes first and then comes the model. Even reading the definitions on google translate / wikipedia or other articles kind of confirm this. First we plan something "design", and then we model it, "add details to the design or give shape the design".
It will probably be useful to review the introduction to section I.
A model is a selectively simplified and consciously structured form of knowledge. An appropriate model makes sense of information and focuses on a problem.
A domain model is not a particular diagram, it is the idea that the diagram intends to convey. It is not just the knowledge in the domain experts head, it is a rigorously organized and selective abstraction of that knowledge. -- Evans, 2003
Another useful lens might be Technical Debt, as described by Ward Cunningham
if we failed to make our program align with what we then understood to be the proper way to think about our financial objects, then we were gonna continually stumble over that disagreement and that would slow us down which was like paying interest on a loan.
The "proper way to think about our financial objects" is the model; the gap that "would slow us down" is the disagreement between the model and the design of the program.
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I want to ask you about my class diagram. I'm making a class diagram for simple web portal for my weekend university studies. Is it made correctly? What would you change if I you were mine? Use cases you can find here Class diagram from use case diagram.
Should I create each user class separately? I mean Admin class, Redactor class, Moderator class etc. I've used privileges field (see User class) to simulate each user's role. Is it correct?
I imagine that ContentManager class holds User class instance and it is used inside Article, Announcement, Advertisement and Comment class to check whether these action is allowed.
I would be very glad for your answers. Here you can find XML file for WhiteStarUML program my XML file
What you should do is create an analysis model of your domain. That model would contain classes like Article, Announcement, etc., as you have in your current diagram. For an example, please refer to another answer I recently posted to someone else's question. The diagram for that answer is shown again here for your convenience:
Notice how the model I provided in that answer has nothing like a UserManager or a ContentManager that just contains code to manipulate other classes. You don't want those, unless people actually play those roles. Notice how it has verb phrases and multiplicities at the ends of every association to tell you why things are related. Notice how there are no mundane CRUD operations on those classes, like create, update, and delete.
Once you have an analysis model in place, then you should allocate actions to the appropriate classes, which will usually mirror your use cases. For example, your Comment class might have an edit() operation. But it might not. You might consider having an operation called replaceComment() in the Article class (if that's how your domain works). I don't know how your domain should work because you are missing an analysis model that teaches it to me!
After you complete an analysis model, then I would make a design model that augments it with solution-domain concerns, such as logging a user into the system. Here is an answer to another question that you may find helpful for moving from analysis to design.
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I have a problem in "include" & "extend" relation between my principal use cases.
I`m using IBM Rational harmony-SE in IBM rhapsody tools. The issue is, how to depict the link between them self, in activity or in sequence diagrams?
In rhapsody, when you want to create a sequence diagram of a use cases, you can use Harmony Toolkit that draws automatically do that, but in a generated Sequence diagram, Harmony Toolkit doesn't consider the "include" and "extend" relation between use cases.
How can I solve this?
Disclaimer
There is no definite answer to this question. This is only one of possibilities, however fully conforming UML and working quite well. Moreover it doesn't provide redundancy in models (each UC flow is defined at most once and the included/extending ones are the only referenced).
Activity diagram
On UC Activity Diagram use Action that is a call to included/extending UC Activity (as part of your flow). Depending if it's includes or extends the action will either have to happen for includes (i.e. it'll be on a flow that is always executed or on all alternative flows) or will be possible to use either a flow containing it or not for extends (i.e. it will be on only some but not all of alternative flows).
Sequence diagram
On UC Sequence Diagram use Interaction Use block (ref), referencing the included/extending UC Sequence Diagram. Like for Activity Diagram it will either have to happen for includes or be on only some of Combined Fragment sections allowing to pass the whole sequence either including or omitting the referenced part for extends.
Note about automated generation
I don't think there is any diagram generation tool that will automatically support inclusion/extension on Activity Diagram or Sequence Diagram of a UC and there are many reasons for that. You'll have to draw diagrams yourself or correct the automatically generated ones accordingly.
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How to model logic of complex operations? For example save methods for root entities where state, versions and various atributes should be handled according to some logic. DTOs and entities exist.
I was thinking about sequence diagram, activity diagram, natural language and some abstract code.
I think sequence diagram is not appropriate because it's more likely for modeling of an interaction.
Activity diagram seems to me too clumsy and I don't know where to put instructions like assignments of attributes. It doesn't look right in a note or description of an activity.
Natural language is ambiguous and there is little information in large volume.
Mayby abstract code could be the right choice. Or its combination with natural language. Is there any recommended form? I don't want to write Java code.
If you mean - complex algorithms, they are probably best modelled by activity diagrams. Since UML 2.0 they have actions for practically all kind of operations (including assignements). That's not the problem.
I agree though that in some cases it would maybe better to use some more informal approach. Activity diagrams are very slow to draw and to layout and the added value is questionable (if no automation is used later on). Regarding the statement that they are "clumsy" - you can always overcome this problem by a nice structuring and hierarchical breaking your model in several levels (as single activities can contain whole diagram inside them).
Maybe a mix would do the work - outline the main steps of the algorithm, maybe main decisions, loops, invocations, whatever is importang for you. Later add detailed description of those single activitis: using pseudo-code, natural language or even another embedded diagram (states, activities).
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I'm referencing a book by bennet, s et al (2002). Object-orientated systems analysis and design 2nd ed. McgraawHill:Maidenhead.
In the book when describing requirements analysis Bennet refers to three types of 'analysis class stereotypes' as a way of breaking down use case diagrams into defined classes.
The first two seem fairly straight forward : an boundary class is the terminus between the user and the system, or the system and other systems that it relies on. An entity class is the 'information and associated behaviour of some phenomenon or concepts such as an individual, a real life object, or a real life event' i.e. the data that you're trying to model or store, such as a person.
Finally, there are control classes which 'represent co-ordination sequencing, transactions and control of other objects'. This definition isn't as clear as Bennet states:
"meanwhile, the boundary class represents interaction with the user and the entity clases
represent the behaviour of things in the application domain and storage of information that
is directly associated with these things"
This rather begs the question what exactly is an application or software domain in this context? How does the control class fit in with these other two definitions?
I think this offers a best case solution :
http://epf.eclipse.org/wikis/openuppt/openup%5Fbasic/guidances/concepts/entity%5Fcontrol%5Fboundary%5Fpattern,%5FuF-QYEAhEdq%5FUJTvM1DM2Q.html
Entity objects represent the persistent information tracked by the system.
Boundary objects represent the interactions between the actors and the system.
Control objects are in charge of realizing use cases.
Modeling the system with entity, boundary, and control objects provides developers with simple heuristics to distinguish different, but related concepts.