Im UML newbie:)
I have abstract class X with methods A and method B (both with implementation). I have class Y with derives from class X.
I want to mark on UML diagram, that class Y constructor must run X.methodA, and Y.method3 must run X.methodB. How to put it on UML diagram?
It is possible to define in behavioral diagram. UML defines operation (behavioral feature) and behavior. Behavior can be connected to operation as a method. You should define owned behavior in class X, and then call it in behavioral diagram defined in class Y. I recommend you to read UML Superstructure document chapter Common Behavior. UML Web
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I know the following:
OCL is a constraint language that to specify constraints on my class diagram models
I know, that in the OMG world for class diagrams there are 3 levels of models: M1 (model), M2 (meta-mode), M3 (meta-meta model)
M3: defines what a class diagram is and what it consists of
M2: Is the meta-model of my problem/domain (e.g.: meta-model of a shelf that contains books)
M3: is the model instance (e.g: a Shelf that contains two specific books)
What i would like to know:
Is there a a common meta-model for class diagrams and OCL; basically something that defines the relationship between model elements and constraints
I suppose it should somehow be defined at M1 level
I am asking because:
I would like to define a meta-model for a constraint language (lightweight OCL) that would allow for me to reason about my model elements (books on the shelf).
How would i connect the meta-models of my domain and of my constraint language?
The OCL specification [1] defines a metamodel for OCL, however there are a variety of problems that mean that practical tools have to 'improve' upon it in proprietary ways. The new Pivot variant of Eclipse OCL prototypes solutions to OMG specification problems and produces an XMI serialization that is credible. It uses an Xtext grammar [2] that you might use as a starting point. This will reveal how much semantic resolution is necessary to resolve the parts of "a.b.c.d". Not easy.
The common metamodel [3] for Pivot OCL is autogenerated by a merge of UML and OCL contributions.
Since OCL may be used to constrain stereotypes or metamodels or even run-time, OCL can be between and pair of Mn/Mn+1 levels.
If you succeed in coming up with an accurate complete lightweight parser, please share.
[1] https://www.omg.org/spec/OCL/2.4
[2] https://git.eclipse.org/c/ocl/org.eclipse.ocl.git/tree/plugins/org.eclipse.ocl.xtext.essentialocl/src/org/eclipse/ocl/xtext/essentialocl/EssentialOCL.xtext
[3] https://git.eclipse.org/c/ocl/org.eclipse.ocl.git/tree/plugins/org.eclipse.ocl.pivot/model/Pivot.ecore
I have some objects that I want to draw a UML diagram for. The first, A, is an interface, and second, B, is an abstract class which is derived from A. The other class are C and D. C and D are subclasses of B.
B has a list of E class objects.
F is a class which all operations are performed in it. C and D class objects creates in the class according to polimorphism operations and then calls its methods according to users input.
Of course, there is a main class. The main class only creates F class object.
I want to draw a UML class diagram. What should the image be like? How can I draw F class ?
The uml class diagram which is writen by my is here.
By the way I know that's the very basic image, I'll edit it after you response.
Based on your description, this is what I think the UML diagram would look like.
For this statement "F is a class which all operations are performed in it. C and D class objects creates in the class according to polimorphism operations and then calls its methods according to users input."
It sounds like you would need to make a relationship between A and F because you are talking about polymorphism. A should have methods. B and C could have those same methods. F doesn't need a relationship to B or C because the relationship to A implies there is a class implementing A but the concrete class name is irrelevant.
Since I can not add a comment. I would suggest two points:
- Maybe the aggregation could be changed in composition if Main class gets an attribute of type F, otherwise a dependency would modelize better the relation between Main and F.
It would be more precise if a cardinality were defined on B side in the relation between B and E.
Hoppe this help to improve the good answer of ProgrammersBlock
Several questions about UML:
Do I include the main class in my UML diagram?
If I do include it, and it instantiates objects, do I draw an empty arrow (such as ->) from my main class to the classes it instantiates?
When do I use the diamond vs. the arrow?
I'm just curious about those 3 things... While an article would also be very helpful, could someone address those three questions?
Thank you so much.
Do I include the main class in my UML diagram?
There are many types of UML diagrams, but I suspect here you mean a class diagram. The answer to your question is literally: if you want to. The beauty of UML is that you can make many diagrams, that vary in detail. Some diagrams will show just a few classes, some many. The idea is that you diagram different parts of the system, at different views, for different audiences. Diagram as much or as little as you like. If you are making a very small application with just a few classes, then it probably will make sense to show the main class. Give it a stereotype or use a comment that identifies it as a "main application class."
If I do include it, and it instantiates objects, do I draw an empty arrow (such as ->) from my main class to the classes it instantiates?
You certainly may, again "if you want to," There will be a dependency here in a way: the main class "depends on" the other classes because it uses them somehow. That is, if main class A instantiates objects of class B, then class A needs class B to compile, so you may show this as a dependency if you wish.
When do I use the diamond vs. the arrow?
The diamond shows aggregation or composition and is used as follows: if class A has a field of class B, then an arrow from A to B with a diamond on the A side is called for. The "plain arrow" just shows a relatively unspecificed dependency. You can use it from class A to class B when class A uses, somehow class B. Perhaps a method of class A uses an instance of class B as a local variable. No containment (composition or aggregation) of a B in an A is implied with the plain dependency.
It seems that you are not an UML expert but this is not a problem. What I would recommend is to simply reverse engineer your code into class diagrams and then add your own notes inside a yellow rectangle having a connector linked to what you consider important.
You will get a graphical representation of your code and would be able to add value comments without having real UML knowledge.
UML class diagram is really simple and can cover all needs of a project. If you don't know UML then just do class diagram by reversing your code and enjoy :-)
I have a class (Class A) which contains objects of type Class B. Class B has three subclasses.
Should Class B actually be an interface and then I can draw an aggregation association between the interface and Class A (and the three subclasses implement the interface)
or
Should Class B, be an actual Class, have 3 sub-classes and all four of the classes (Class B + 3 subclasses) implement the interface (through Class B)?
I would say to ask yourself these questions:
1. Would you ever create an instance of Class B? If yes, then it should be a regular class. If not,
2. Should class B contain any functionality that the derived classes should be able to use? If yes you should create an abstract class that the other classes inherit, if no, make it an interface.
If Class A contains objects of type Class B that means that Class B is instantiated, therefore it can't be an interface.
I have 2 questions about class diagram. firstly if i have used an object of class A in my class B , in drawing the class diagram i should associate class A with B . or association is just used when a class uses a method of the other class.
my other question is almost similar. if in class A i have a dictionary< class B, Class C> , then in class diagram should i associate the class A with B and C and say 'use'in connection?
In my view, in both cases it is a Dependency you show, not an Association.
In UML, the relationships tend to cover:
Dependency
Association
Generalization
Relization
In your case, the closest is a Dependency from Class A on B and C (represented with dashed line with arrowhead pointing to B and C). You're not directly associating (via aggregation or composition), you're not generalising A into B or C (or vice versa) nor are B or C realizing A (or vice versa).
If in doubt, I strongly suggest using a UML reverse-engineering tool and writing the source-code skeleton you know of, and see what it suggests. I use, but don't necessarily recommend, Enterprise Architect.
Associations are used when the A class "will" have an attribute of type B. I.e. at the UML level this is indicated using associations. At the code level, e.g. Java, these associations are transformed into attributes in the participant classes (one or two depending on the navigability properties of the association)