Could you please let me know whether flow chart can be consider for use case modelling? As far as I know it just represents a flow of events and do not have any actors, so cannot be considered for modelling.
Can some some experts confirm this?
Flow charts are the ancestors of activity diagrams and as such very rudimentary. You can use flow charts along with use case modeling, but it is not a good idea. First you will limit yourself in the language (think of a native speaker vs. a foreigner that knows only a little vocabulary). Second is that activity diagrams are matured to a standard within UML. So you can expect more people to be able to read and understand them correctly. And last: activity diagrams are the basis for BPMN which is going to be the next step after use cases (it brings a whole set of new standardized language elements which allows expression of what is in and behind a use case).
And yes, your basic assumption is correct: no relation to actors. So you'd need to find ways to express that outside the flow chart.
See also Wikipedia.
Related
I'm trying to create a Use Case Diagram of Order System. But I'm curious if the 'send notification' and 'add order' is connected since before ordering, the inventory will check for the stock. I'm thinking of connecting the two using 'extend'. What do you think?
Whenever you wonder if use-cases are related because of some sequential or causal relationship, you are no longer in use-case analysis, but in one of the following situations:
Functional analysis: you’re doing functional decomposition, i.e. breaking down a functionality in more elementary functions (e.g. the includes for Ship order): this is not forbidden but leads to very complex diagrams that are difficult to read and use in practice due to unnecessary details and mixed levels of abstraction.Solution: don’t! Simplify your diagram and focus on user’s goals.
Designing a flow of activities: this is wrong, since there shall be no order/sequential relationship between use-cases, and use-cases shall not be confused with events or preconditions(e.g. item is not out of stock) Solution: go for an activity diagrams, which are meant for exactly this kind of modelling.
misusing use-cases for user-interface design (suspicion that all the generate xxx corresponds to windows to show data to the actor): this usually leads to bad user-interfaces and incomplete analysis of the user’s goals.
I think your (impressive and comprehensive) diagram corresponds to the first two situations. I recommend to simplify, focus on the user goals, and for each use case that is more complex, make an activity diagram for the flow.
I am very concerned when I see in the table “use-case(process)”, and it appears that this is an exercise you are trying to do. This is plain wrong: a use case is an actor’s goal and not a process. Processes are typically modelled with activity diagrams. If this comes from an UML tutorial, then immediately change tutorial!
I’m trying to prepare UML model for my project. It’s quite complex however I focus on one of use-case. In short term, use case name is “Edit patient results” and actor “Doctor” uses it. In fact, entering results triggers always the set of following actions:
List item
Normal Ranges calculation
Related Expression calculation
Interpretation merging
Assuming that I have my use-case diagram prepared as follows:
My questions are:
How shall I draw actions that are triggered automatically? As extended use-cases like this?
How shall I draw “Edit patient results” use-case realization? Each edit operation involves several software components interactions, shall I use collaboration diagrams? (how to join my main use-case with them), maybe something else?
How to draw sequence diagrams to show actions sequence and parameters passed? How to join these diagrams with my use-case.
What is the best way to show use-case realization
I'm using Enterprice Architect.
Thank You !!!
No. These are just activities which are part of scenarios inside the use case. Trying to make the use cases is functional analysis the wrong way. A use case synthesizes a number of steps under a common goal/added value.
A use case realization is a collaboration (bubble with dashed line border; along with the UC in the toolbox). The collaboration contains diagrams which show how the single classes communicate/collaborate to realize (parts of) the use case. Use a Realization from Collaboration to Use Case.
Put the SDs inside the collaboration and group/name them reasonably.
see above
As to your comments:
Edited 2.
I never found a good use for Collaboration Use and I've done a lot of successful UC modeling. So you can probably live without it as well.
Put Actions inside an Activity representing a scenario and connect them as desired. You might look into BPMN as well.
Firstly, I'm still quite new to UML; but, highly interested and am attempting to learn as much about it as I can.
With that said, I’m in a situation where I’m directed to assemble a ‘Context Diagram’. I feel as though I understand the concept of what a context diagram is and how to create one, so I think I’m ok there. Basically it is identifying the system and the components or actors it will interact with. It applies the focus on the system, and not the actors. Kind of like a Use case diagram, but not focusing on the actors. If I’m wrong, please tell me.
I read somewhere that Context Diagrams are not actually part of UML. I also read, somewhere, that, if you use a Context Diagram, it falls into the Component side of things. When I read about Domain models, it seems like it should be there.
For my current situation, I know a simple answer is to simply create the diagram and move on, as that is all that is required. But, for my interest to better understand and leverage UML, I know there is a right way and a wrong way. If I were in a case of a bigger project, what would be the right way?
Now here is where my question begins. I’m using Enterprise Architect, create my project, and start to create a model. Does it belong in a Domain Model or Component Model? What is the difference between these two? Or even more. As it is an aide to help identify requirements, should it go there? Or does is just simply depend on what and how I want to convey it?
The Domain Model is where you standardize the vocabulary that everyone on the project will use to communicate in a consistent manner. The development team are experts at software development, but they may not have any experience in the domain (e.g. banking, air traffic control, healthcare) in which they are being asked to work. So you get domain experts and modelling experts together to build a model that describes the domain, answering important questions like "how are account fees calculated?" and "how does a pilot know what route to follow?" and then this model is then passed to the development team to provide them with the important domain knowledge that they will need. I would use UML class diagrams to create a domain model.
A Context Diagram shows the system being modeled in relationship to external systems. It could show data flowing in from and out to external systems, modeled by a data flow diagram (not part of UML). It could show behavioral interactions between the system and external "actors", modeled by a UML use case diagram. It could show the system's physical connections to other systems, modeled by a SysML block diagram. Whichever you choose, it will be on page 1 of your design document, so choose wisely!
You (can) create context diagram by making any element composite. Then drag the element itself onto that diagram as link (not instance!) and highlight it by making the border a bit thicker. Finally insert related elements from the context menu (differs from EA version to version). Layout the diagram and now you have your element in the context.
A domain model is usually a class diagram showing the (business) domain on a higher abstraction level.
As you have said, Context Diagrams per se are not part of the UML spec. There are plenty of ways to do a context diagram, but the UML way is to use a Use Case diagram, with or without supporting narratives and scenarios. Start with this, which is a broad overview of different types of Context Diagrams. Then, investigate use case diagrams, use case narratives, and activity diagrams. If you need to go into more detail than a use case narrative can easily do, get into use case scenarios and sequence diagrams. Here is a pretty good use case narrative template (feel free to leave out sections such as "scope and level" if they are more than you need, and consider adding information about what triggers the use case and where you go when you finish it--these two are required for scenarios if you go that far).
Keep in mind that use case narratives and use case scenarios are often confused. (Some people will say that I am the confused one; I will invite you to judge the matter for yourself.) A narrative is an explanation of an entire (single) use case, and may be supported with an activity diagram. A scenario is an explanation of a single path through a single use case, and may be supported with a sequence diagram.
For example, a use case will generally have a basic flow of events, along with a number of alternate flows. The narrative describes the entire process. The basic flow and each alternate flow would each be a separate use case scenario.
I suspect that it's unlikely that you will have to get down to the level of use case scenarios. You will probably want to put a use case diagram together, and possibly prepare narratives and activity diagrams for each of the use cases in the diagram.
What is the practical difference between using flowchart diagrams and UML activity diagrams?
I have some thoughts, but maybe I'm missing an elephant in the room?
Flowchart diagram:
Widely used;
Easily understood by non-programmers;
Old?
UML Activity diagram:
Standardized;
Supports concurrency;
Less known syntax, but still simple enough.
For my case of ad-hoc documenting a particular block of application logic, I decided to go with the flowchart diagrams. More people in the company will be able to understand them.
It might seem as a preference, but if we have a standardized language for describing software systems, Why do we use something else? This can lead to bad habit of overusing flowcharts. Activity diagrams are really simple. But if you decide to describe a more complicated aspect of the system or try to change the part you are describing, you might have to switch anyway. So just use UML and prevent confusion in the future.
As you note, Activity diagrams inherently can include concurrency and timing. If you look at this example cribbed from Wikipedia, shown below, you can observe the section with two heavy horizontal bars, and two parallel activities of "present idea" and "record idea". That is read as "start these activities in parallel, and continue only when both are complete." Flowcharts can't express this within the notation.
Practically, using activity diagrams lets you think clearly about concurrent processes. I think you'll find that anyone who can read a flowchart will quickly adapt.
Activity diagram by spanish Wikipedia user Gwaur CC BY-SA 3.0, via Wikimedia Commons:
According to the Agile Modeling site:
In many ways UML activity diagrams are the object-oriented equivalent of flow charts and data flow diagrams (DFDs) from structured development.
From IBM:
However, flow charts do not include And states, and flow charts for operations cannot receive events.
Probably this is why flow charts are easier to understand because activity diagrams have the notion of object-oriented development and concurrency.
You can generate source code from UML, and vice versa; hence the "standardized" characteristic you talked about.
UML in itself is used to share your understanding. Share the understanding in a standardized way. Since your case is ad hoc and the primary usage of an UML diagram is to provide an informal sketch, activity diagram can be used here. But so can flow charts as there are no parellism involved here. I have always found the following argument to be helpful. The artifct that i am producing is going to benefit whom? And can i express the flow in a self explanatory way using a flow chart. And if yes, then you should go ahead and use flow chart. But if your class diagrams, sequence etc are in UML format, it would make sense to have your activity diagrams in UML as well for consistency sake(The argument here would be, if people can understand class,sequence UML semantics, then y not activity diagrams.).
I have an Access db I wrote that I've used for my checkbook and budgeting for the last 3 years. I've never written a program before, but I've decided to write the db into a stand alone program. My only experience, besides the simple VBA in the db itself, is an Intro to C++ class and an OO Logic class.
Even though I know what I want the program to do (because it's what my db does now) I want to approach the planning and design as properly as possible, so I can write the program as properly as possible, so that feature additions and maintenance are easier.
I need help planning. I guess UML diagrams should be first. What UML diagrams do I need to do? And in what order? I tried to do a use-case but since the program only involves me, my money, the bank, and the stores, it seemed pointless. Or was I thinking about it wrongly? Do I need to diagram my money and my budget inside my account? I don't know. I need help on how to proceed. Thanks.
It's good to have a set of UML diagrams to keep track of what is happening, but to remember in the end that documentation decays - your code is your design. That said, UML are good for planning and recalling bits and parts. There's a large dose of personal experience involved here, so feel free to take what you want and leave out what you think don't applies.
Use Case Diagrams
Skip this, and just write use cases instead.
Class Diagrams
I find them useful for planning the big picture view of an architecture, but I usually would leave out all the method names, or only leave in the relevant . I use it to illustrate the logical model of your classes
Sequence Diagrams
One of the more useful diagrams especially for business logic, and flow of data. I always find myself sketching sequence diagrams for complicated data-flow and especially when there are events being dispatched.
Object Diagrams
Shows the interaction of objects at run-time. I usually draw those for complex object interactions, and not the 'academically correct' ones. I think it is less useful than sequence diagrams.
Flow diagrams
Good for websites if you have complicate flow
State Transitions
Important if your application has many states. Again, just sketch out the most complex system, there is no need to have one for every sub-system.
ER Diagram
I know this is not UML, but a good database design upfront is important, and an ER diagram would help you to organise and plan how different tables relate with each other
Since your application is for personal use, I think you only really need two diagrams, maybe three. You can use a Use Case diagram if you want, but you will probably be better off with just a list of use cases. Since no one else has stated it, a use case is a requirement where you state something you're going to use it for. These help you define what features you need.
Next you need the class diagrams for how you're going to organize your program. A class diagram shows which classes you have and how they're connected. This is useful for figuring out if your program is too complicated or if you're using the antipattern known as the blob. If you have a lot of lines connecting classes to each other, you might want to reorganize to see if you can make each class more cohesive and if you see very few classes, you might want to check for a blob antipattern. An antipattern is a common occurrence which is bad for readability or maintainability. Class cohesiveness is defined by if each class has exactly what it needs. For example, if you decide to have a class for your account, it doesn't need to know information which isn't related to your account, like the street address or name of your bank.
The last UML diagram I think you'll need is a sequence diagram which shows how different objects in your program will interact. This will help you better understand the interactions your classes are doing and decide if you need to better organize them if they're getting too complex.
Those are the UML diagrams you might need. You might also want a network diagram to understand how your database is going to connect to the bank's website and get the information you need.
The diagrams are there just to make you understand what you are doing and keep you on track. I guess you already know that. In your case, i Believe a detailed use case will suffice, just to make sure you handle all the features and dont forget anything. (Reminder: Use case is not a diagram. it is text)