I'm trying to model a pipeline in UML as an activity diagram, and I'm not sure how to describe a process consisting of multiple steps, where the user can decide which parts to execute:
-case 1: only A
-case 2: A and B
-case 3: A, B and C (Note: B can not be skipped in order to process C)
But if I put it into an activity diagram, I have to draw each sub-workflow multiple times:
So I don't think I'm doing it right. Maybe someone could help me with it?
There are some issues with your diagram:
You are missing the square brackets around the guard. So it should be [Yes], [No], etc.
The middle part of the decision has no guard, so the flow will take that way in any case.
The lower Activity has 3 incoming edges, but only one will have a token. So it will never continue. You need to merge the flows from above prior to it.
Basically you could leave the actions this way. I'd probably pull out A (oh, I see that bruno suggested the same) since it's performed in all cases. So your decision will be left with two outputs. Although from a "physical view" your decision is made first (the user has to interact) will be after A has already been performed, the output/consequences will be the same. So this is kind of a business decision.
it is ok except that yes/no is not enough to separate three cases :-)
you can also move the test after A being executed in all case
In the end what I was looking for was a nested activity as shown in https://softwareengineering.stackexchange.com/questions/331641/how-do-i-represent-nested-actions-in-a-uml-activity-diagram
Related
I have the following problem to resolv. Given the following UML diagram:
I need to complete the diagram doing the following steps:
a) When an employee has a skill, the relationship between the employee and the skill shows years of experience.
b) A worker may have another employee as a manager and a worker who is a manager must manage five or more workers. As a manager, you can determine which workers he manages, but a worker can not determine who is his manager.
c) An activity can have a maximum activity precedent and any number of upcoming activities. Using these roles, we can show how the activities are arranged. Given an activity, you can only determine their own activities (if you have), but not what your previous activity (if any).
d) A worker is not simply associated with a set of skills, but a worker has skills. In particular, every worker should have three or more skills, and any number of employees can have the same ability.
e) A project is not simply a set of activities associated with, but contains a project activities. Specifically, a project must have one or more activities, and activity must belong to exactly one project.
f) Projects and activities are a specific type of job.
My solution is shown in the following picture, but because I am new in this I would like to check if is fine.
Thank you in advance!
Looks good in most parts. Honestly I don't understand the later parts of c)
Your -boss relation is wrong. Your Northern Koreans should not have a private known boss. Instead there's only the other way around and the boss has - let's call them - -slaves. If you put in a private -boss it actually means that the slave can navigate to its private boss which is explicitly not wanted. Only the boss shall know the one he's responsible for. So actually the object itself is the boss object. As a thought, since only the boss should have those 5 employees, it could be an idea to create a separate boss object like this:
Note that this might also have drawbacks since Boss is now actually a different object than Employee, but it seems to fit the requirements.
Point f) seems to call for a generalization. So you would need a generalization towards SpecificJob. This would be an arrow with open triangle, not the one you used:
This actually reads Project and Activity are specific kinds of Job as they both inherit from the latter.
I am trying to model a certain behaviour, where couple of activities in differents swimlanes supposed to be processed in a loop. Now BPMN uses tokens to ilustrate the flow and paths taken. I wonder how such tokens work in case of loops. Does every activity iteration creates a token which consequently travel through the connected activities?
E.g. Let's say Activity1 will be performed in a loop 10 times. Will that create 10 tokens where each will travel through the remaining activities of the process? Such behaviour would be undesirable, however if I am not mistaken multi-instance activities work that way.
The only solution on my mind which would comply with BPMN specification would be to create a Call activity for the whole block of activities and then run the Call activity in a loop.
Can anyone clarify for me the use of loops and multi-instances in BPMN from the view of tokens?
Thank you in advance!
Based upon my reading of the documentation: https://www.omg.org/spec/BPMN/2.0/PDF The answer from #qwerty_so does not seem to conform to the standard, although in part this seems to be because the question also seems imprecise or at least underspecified.
A token (see glossary) is simply an imaginary object that represents the flow unit in the process diagram. There are at least three different types of loops specified in the standard, which suggest different implications for the flow unit.
Sections 13.2.6 and 12.2.7 describe Loop Activity and Multiple Instance Activities respectively. While the latter, on its face, might not seem like a loop, the standard defines attributes of the activity that suggest otherwise including: MultipleInstanceLoopCharacteristics and ExpressionloopCardinality.
In the former case, it seems that the operational semantics suggest a single flow unit that repeats multiple times according to some policy or even unbounded.
In the latter case, the activity has "multiple instances spawned," including a parallel variant.
That multiple instances can flow forward in parallel, on its face, suggests that the system must at least allow for the possibility of spawning multiple tokens (or conceptually splitting the original token) to support multiple threads proceeding simultaneously along different paths.
That said, the Loop Activity (13.2.6) appears to support the OP's desired semantics.
Let's say I have a collaboration diagram that models a process named CheckMessage which is quite complex and spans over few lanes and pools. Now I would like to model another process, e.g. CreateMessage which would make use of the previous process to check first if message doesn't exist already or if all its fields are valid, etc.
The thing is, that both processes make use of the same swimlanes and pools. What is the proper way to model such interactions? I was thinking to model CheckMessage as a sub-process of CreateMessage, however sub-processes can't be attached to pools or lanes - if I understand it correctly they just stay within a lane of activity which invoked them. Can a Call Activity encapsulate such beahviour (cross pools and lanes)? Or can I somehow reference the CheckMessage diagram as a whole?
Thanks in advance.
I could think of the following approaches:
Using Diagram Reference: This is used quite often when you want to switch easily to the more complex part. The disadvantage is that, unlike Fragments in SDs, you do not have ways to really connect flows in and out of referenced diagrams.
Repeating parts of the process: here you just pick those actions from the complex process which ought to interact with the other process. You can highlight that by putting a boundary around these and adding a diagram reference as described above.
Call Activity: This is another valid way. Here you have an activity which you instantiate as action. The advantage here is that you can add pins for input and output parameters.
I guess there is no silver bullet and you have to choose what is appropriate in each case.
Edit Regarding #3 it looks like that:
(this is an example and not to be used in practice)
The Action to the right is an instance of the Activity as you can see by Ctrl-L (show parent).
I have a sequence diagram in Enterprise Architect.
In it is a process which can be initiated by one of two sources: either a timer process or a manual one (a user hitting a button on a GUI screen).
How do I show this on the diagram, please?
A sequence diagram does not allow you to show two alternative invocations of the same operation. You could achieve this in an activity diagram using two different receive events leading to the same activity, but in a sequence diagram you can't draw two messages to the same sequence.
What you can do is call other sequences from within a sequence.
You do this by first drawing the sequence for the process, not showing how it is initiated or by whom but only what happens within the process.
You then draw two separate sequence diagrams for the two different cases, and into each you drag the first sequence diagram and drop it as an "Interaction Occurrence."
Finally, you draw a message from the actor to the interaction occurrence. The occurrence can be double-clicked in the diagram, which opens up the sequence diagram describing the process.
A related problem is, of course, that there is no standard way of showing spontaneous occurrences (timeouts) in sequence diagrams, since they focus on interaction between a caller and a callee (often in a cascade). The simplest way of dealing with this is to create an actor "Clock" or similar, and have it initiate the process.
You might want to introduce an interface (or a superclass) that is common to the timer process and the manual invocation and set that as the user, as the calls (I assume) are likely to call the same basic method anyway.
If they behave quite differently, I'd go with Uffe's advice and create 2 diagrams.
Some tools also allow for using fragments in sequence diagrams (see corresponding help text for Enterprise architect).
Then you may use e.g. the "alt" fragment. Note the advice in the given link, though: "sequence diagrams are not intended for showing complex procedural logic".
Just for my personal wiki, I want to draw a diagram that shows how a message is processed via a couple of Message Queues.
(Like, xml message comes from source1 to the Queue1, then it is passed to a system where the message is converted into another format and...)
What kind of UML diagram should I need here?
And additionally, how do I show a Queue in UML?
Order and time are best seen in an Sequence diagram. Also the communication between the different parts (source, queues) and parameters will be visible.
A queue is just an object (the squares at the top of the diagram).
Sequence Diagrams are a good choice but they have limitations when used for interactions with a large number of steps. They excel at describing the steps to a single operation, such that the actors are related to the behavior required. I try not to left any single sequence diagram take up more than one page. If I need more, I break it up into two serarate diagrams because I'm usually wasting whitespace due to the calling depth and the interacting quickly becomes harder to understand instead of easier.
You might use two types of diagrams. On a system-level diagram, show the interaction between the queues (or their hosts), and on a Sequence Diagram show the steps taken within a single host.
I think that the best good is an activity diagram. In my view it is the best way too show process flow. Sequence diagrams are harder to understand and also has a lot of clutter (the lifelines) which just bother the reader. And having two diagrams just makes things complicated