I have a nodes. Two nodes makes link. Multiple links make chain.
How can I draw this relationship in UML?
I thought Chain as a aggregation of links. But I have not come across any diagram stating such relation with “filled diamond with 1..* in it”.
Sorry I cannot upload the picture of mine. Since the “.violet.class” format is not supported by stackexchage.
Thanks
Edit : Node is similar to the any point in map.
Link : (source node , destination node).
Chain: vector[multiple-links]
So node will exists irrespective of the link. Whenever you create a chain a new links will be created and it lives only the life time of chain.
Here is a UML class diagram modeling what you stated.
A chain has a predecessor and a successor. Either might be 0.
You might add a constraint that in a chain the first must not have a predecessor and the last no successor and also that no circle is allowed (all depends on the context where you model this).
Related
I'm modelling an activity diagram for a project. Directly after initial node is it okay to use a decision node. I just google for it. But I fail to find similar examples even.
Eg:- imagine a person can Search for a dog name or Select the category animal, then dog likewise at the very beginning.......
One of my team mates mention that according to above example those are two different activities and we should create two activity diagrams for it.
This is allowed under condition.
The rules concerning the input flow(s) of a decision node are (formal 2017 § 15.3.3.6 Decision Nodes page 390) :
A DecisionNode shall have at least one and at
most two incoming ActivityEdges, and at least one outgoing ActivityEdge. ... If the DecisionNode has only one
incoming edge, then it is the primary incoming edge. If the primary incoming edge of a DecisionNode is a ControlFlow,
then all outgoing edges shall be ControlFlows and, if the primary incoming edge is an ObjectFlow, then all outgoing edges
shall be ObjectFlows.
Also knowing (§ 15.3.3.1 Initial Node page 387) :
The outgoing ActivityEdges of an InitialNode must all be ControlFlows.
that means in your case, and supposing there is no other input edge to the DecisionNode, all outgoing edges of the DecisionNode shall be ControlFlows, else this is not allowed
Your team mate isn't wrong. This is a design question which should have been clarified beforehand. Activities are functional parts inside of use cases. They represent scenarios like "sunny day", various error scenarios, etc. And again one step back the use cases represent the added value the system under consideration represents for its primary actor.
Now from your examples it's hard to tell what that system should be. Search for dog name could be a use case, but in which context? Is it to name a new dog or to search for an existing dog in a database? Same for Select animal category(and then dog?). Both do not make much sense as use cases. Once you come up with meaningful use cases you can tell exactly which steps the activities should have as actions. Only then you can have the need to decide. The decision which use case to actually use it outside the system and you wont see the steps done for it.
As a recommendation: Bittner/Spence have an excellent book about use cases which (unlike the UML specification) makes a lot of sense. There are also other well known authors teaching the same school (along Ivar Jacobson).
I'm trying to create a class diagram for a node-edge relationship, as it would be found in a directed graph. I want to convey that Nodes have references to Edges, and Edges also have references to Nodes.
Every Edge needs exactly two Nodes (source and target).
Would this be an acceptable way to model this?
Yes, this diagram expresses perfectly what you describe in the text. The doubled association is right: each association expresses something different.
You are somewhat more precise in the diagram than in the text, since you show that each node has inEdges and outEdges, whereas the text just mentions the reference to Edges without being more explicit.
A common variant for the implementation of directed graph is that the Node knows only its outEdges. If this is important, you may express it with navigability, with an arrow in direction of sourceNode and a cross on the side of inEdges. But this practice is relatively rare in the model.
For an undirected graph, you could have only one association with a multiplicity of 2 on the side of the nodes.
I have the following UML containing the class School which (in my example right now) can only have one TeacherRoom.
My Question now is what is the official notation for this UML or should i remove the <<use>> assosiation because it is obvious?
Obvious because i am saving a instance of TeacherRoom in my School instance?
I would define it like that:
The fact that you have attribute teacherRoom : TeacherRoom in class School implies that School is using TeacherRoom, so the ≪use≫-dependency is not needed.
You also have a composition association to TeacherRoom. This means that, in addition to the attribute, you have a second relationship with TeacherRoom. So you may remove either one.
According to my understanding of section 10.4 of UML 2.5.1 specification, Usage dependency decribes the fact that a given Component requires an Interface or Services.
So I would remove it, as this has nothing to do with the fact that a "School" is composed of "TeacherRoom".
My second point is your "teacherRoom" property which has more or less the same meaning than your composition so I would remove one of them (Property or Composition).
Since you wrote
can only have one [typo corrected by me] TeacherRoom.
you need to add a multiplicity 1 to the right of the association (and as commented and answered to remove the diamond). Also rather than an attribute in School you should use a role name teacherRoom at the association and make it an owned property by adding a dot.
Some additional remarks to composition: Composition is (my personal impression) something that causes more confusion than it actually helps building models (just look for questions asking about its semantic and/or look out for wrong usage of it). Even worse is the shared aggregation which caused (and causes) even more confusion. Now after many editions, UML 2.5 defines that hollow thingy as what it is: nothing. Just read the box on p. 110. So back to the filled one, the composite aggregation. Basically it's about lifetime of objects, so whether there's an owner of an object who is responsible of its lifetime. When you make a car composed of its wheels, that's obviously not right since the wheel will live on without being attached to the car. Only the car is no longer a car. But that will be expressed by attaching a multiplicity of 4 to the wheel. Any car with not exactly 4 wheels is no longer a car. No composition at all.
So where can you use composite aggregation then? I have only 2 applications in mind. One is for storage managent. Something that had been important in the early days of computing when dinosaurs like me fought along with hard disks at cupboard size that had 20 Megabytes! Only a few border cases still need indication for memory management. The second case would be security. Indication that something has to be deleted along with its parent. And that's still valid. But then this is the only real application for composite aggregation.
I have two components A and B. I want the model to show that they both <<include>> and <<use>> the third component. Which picture is correct, the top or bottom one?
Often, when you have two possibilities in UML, both are correct. But not here. I am afraid, both are bad.
According to the current standard 2.5 :
A Usage is a Dependency in which one NamedElement requires another
NamedElement (or set of NamedElements) for its full implementation or
operation. The Usage does not specify how the client uses the supplier
other than the fact that the supplier is used by the definition or
implementation of the client.
So, in UML <<use>> means "must have for some use". And notice, it is absolutely independent on the containment/inclusion relationship. The object we are depending on can be even contained, for it is not said we need it for creation of the dependent object.
We can use a component that belong to anywhere. But in the including (top) diagram we can't show the usage. So, it won't pass.
As for the second sort of relationship, including, there are greater problems here.
The standard UML component diagram has no "include" stereotype. But it is allowed to use elements of other diagrams.
But the component is not a class, it is an object. So, your component C simply cannot belong to both A and B. The other diagram fails, too. And if you want to have two different objects/components based on the same class or package, absolutely different diagram appears.
So, either A or B has its own instance of C and uses this instance. It is clean, without peeking into the other component.
If you use the tool that has not that containment connection, use the "include" association from the use case diagram.
I have also a strong suspicion that you could need not Component, but some different diagram, for your wish to put one box into different ones is unnatural.
According to UML specs every Element can have an owner. Whether he has/must have an owner is determined by method mustBeOwned(): Boolean, which by default is true (see 7.8 Classifier Descriptions in specs).
In cases when an element is completely enclosed by its owner (such as a class in a package) it is quite obvious.
However for relationships (normal, directed, generalization, …) I didn't find any specification. Is the "source" (for directed at least) also the owner?
Is it the first common owner in the ownership chain? So for example association between two classes in a same package, the owner of the association would be the package.
Or is it simply not defined and it can be whatever I want?
To be honest, the definition of terms in Superstructures is still very poor.
Looking closer it's even worse (citing from ptc 13-09-05).
Relationships (p. 15)
A Relationship is an Element that specifies some kind of relationship between other Elements. Descendants of Relationship provide semantics appropriate to the concept they represent.
Connector (p. 235)
A Connector specifies links that enables communication between two or more instances. In contrast to Associations, which specify links between any instance of the associated Classifiers, Connectors specify links between instances playing the connected parts only.
I wasn't aware that they made a difference between both. Appears to be quite picky.
Association (p. 206)
An Association classifies a set of tuples representing links between typed instances. An AssociationClass is both an Association and a Class.
No mentioning of Relationship as being a parent.
Now seeking for the truth about owner
owner (p. 37)
/owner : Element [0..1]{union} (opposite Element::ownedElement) The Element that owns this Element.
mustBeOwned (a bit down)
mustBeOwned() : Boolean
The query mustBeOwned() indicates whether Elements of this type must have an owner. Subclasses of Element that do not require an owner must override this operation.
So here one is stuck unless reading to
Association (p 209)
Ownership of Association ends by an associated Classifier may be indicated graphically by a small filled circle, which for brevity we will term a dot. The dot is to be drawn integral to the graphic path of the line, at the point where it meets the Classifier, inserted between the end of the line and the side of the node representing the Classifier. The diameter of the dot shall not exceed half the height of the aggregation diamond, and shall be larger than the width of the line. This avoids visual confusion with the filled diamond notation while ensuring that it can be distinguished from the line. The dot shows that the model includes a Property of the type represented by the Classifier touched by the dot. This Property is owned by the Classifier at the other end. In such a case it is normal to suppress the Property from the attributes compartment of the owning Classifier.
Answer?
Most likely (!) connectors do not have the mustBeOwned constraint and can be owned in which case you will see the dot that has been introduced with 2.5. Else they are probably not owned.
To my understanding, the relation is generally not owned by elements it connects. What is owned is the association (relationship) end's and corresponding attributes/properties. Section 6.4.2. of UML specification 2.4.1 clarified this much better than your linked 2.5 beta. I would suggest that you use the current official version of specs rather than the beta one. I find the 2.5 being kind of unintelligible, the table of contents looks very chaotic.
The Relationship itself exists independently, it has no owner. Except when stated otherwise by concrete type of relationship (as in case of Generalization).
Which brings me to the main point of my answer by question. Why do you need to know?
I have been reading and explaining the specification for years now, but never came across such a specific question, which moreover is relatively clearly stated in the specs.
I would recommend to look at concrete relations and search (Ctrl+F) for "owned" (an Association has more than a page of text on this very topic in detail starting on page 40 in 2.4.1).
I myself have been trying to figure out what can own an instance of Association. I am using 2.4.1. This appears to me to be a(nother) case of the standard not actually being usable.
I haven't looked at all of the specializations of Relationship. I have looked at Association. It inherits owner from Element. The property is noted as a derived union. I can't find any property of Association (or any of its antecedents) that subsets owner. That being the case, I don't see how Association can actually have an owner.
I think that it seems reasonable for a Package to own an association.
I am using a UML tool that certainly does initialize the value of owner for associations. I am programmatically interpreting models created in that tool and using them as input for other modeling tools that I am working on. The makers of the first tool obviously had to just make up / guess at things and now I have to decide whether what they did was actually rational and if I want to agree with their conclusions (which happen to allow Classifiers to own Associations, which I think is weird) or do something else. Thanks OMG. Grrrr.
I wonder if older versions of the spec were any more clear?