What is corret use of this model .. the 1. or 2. ? ... or should have 1. extends instead of include ?
I guess the UC in #1 should read "item selection" and not section.
Both of your designs are wrong in the one or other way. "item selection" is not a use case. It does not deliver any value to Actor (at least none I could imagine). So you are trying to put a CRUD into a use case. Re-think on what the actual value is the Actor expects.
Now for include/extend: Avoid them where possible. Once you start decomposing use cases you got it wrong and if your use case diagrams resemble spider webs your design is simply broken. Use cases are synthesized, not analyzed. While the first tried to build a complete picture, the latter is something you need in code design to cut it into manageable pieces.
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I am trying to draw a use case diagram for navigation. However, I am not sure if it is correct since the 'call out address' base use case is being used as included use case.
Any comments on the above diagram please?
This is not a use case diagram. Your bubbles contain Actions being part if some Activity carried out by a use case. A use case shows added value an actors gets from the system under considertion. Please start at square one!
I recommend reading Bittner/Spence about use case modelling. The best read you can get on that topic.
With this Use Case diagram, I'm unsure if I'm currently doing it correctly or not. Checked online and each site is giving me a different answer. I just need a direction or someone to correct me.
This is interesting as I am currently going through the exact same discussion with a client...
I would say "no" simply because I am unsure of what this actually represents.
A use case must bring a benefit to a user, and I really don't this in this diagram. What does Actor0 actually trying to accomplish? I do not get this from the diagram.
Did you write down statements before trying to do this? I find that going to a whiteboard and writing down what your actor's goal and how you see this happening so that the actor achieves the goal is a good start to better understanding the use case and differentiate the system being built from external systems. One way to do this is through a set of user stories (or use case slices).
And answering Thomas Kilian's excellent questions will also help you in this task!
Also, you are doing something that I see too often from people starting with use cases (and sometimes with UML experience): use case decomposition as a set of actions - basically trying to model a set of activities by breaking it down. Doing that is typically the second step in your analysis (e.g., by using activity and sequence diagrams).
No. Only "Register" (what?) and "Add/View Details" (which?) can be regarded as use cases since they add value. Neither "Login" nor "Main Menu" are use cases. The first is a constraint and the second an implementation detail.
Let's assume that there is a UseCase called "Start Pattern Recognition". But when stating pattern recognition, it's mandatory to either to train a new model or import existing (pre trained) model. One of those option must be performed. I tried to represent that in UML as shown below (I used Includes instead of Extends since it's mandatory to perform either one of this UseCases). But I'm not sure whether it is correct to use "Extension Points" with Include UseCases. Is this correct or Is there any other way to do this?
It isn't correct; there is no analogous concept to extension points for includes in the UML spec. As xmojmr has very correctly stated, you really have your inclusion backwards.
This is easy to do, because it's easy to get caught up thinking about the order that use cases occur in over time. The use case diagram doesn't have anything to do with time; it just states what things a system does, who or what interacts with it and what uses what.
When you are ready to think about the flow of a use case, think about it in terms of an activity diagram. Also, look at the idea of a "use case narrative", which documents the behavior of the use case.
By the way, extension points in a use case diagram are optional.
I just want to determine if I am using extend and include correctly. If I am using either incorrectly somewhere here please indicate where, and if possible, why it is incorrect.
https://imageshack.com/scaled/large/163/nlnk.jpg
Cheers.
Rules for using <<include>> and <<extend>> are simple:
<<include>> defines a sub use-case which is always included in the general use-case: use-case -include--> sub use-case. Usually it's used to denote a distinct part of a use-case or a common part that can be reused by other use-cases.
<<extend>> defines an optional sub use-case that can be executed upon certain conditions (which should be defined at a lower level design, not in use-case diagram). Here the direction of the relation is opposite to the <<include>> relation: use-case <--extend- sub use-case.
Apply these rules to your diagram and figure out if it's correct.
It looks as though "secure login" is required to be performed prior to the other activities that you link with <<include>>. Include implies that the use case also runs the included use case every time which in this case is probably not what you intend (just one login per session). You can always create new stereotypes, such as <<precedes>> or <<requires>>. Using them consistently will allow you to convey your meaning.
I find this piece of advice before when I'm trying to distinguish the difference between using extend and intend in use case diagram.. I hope it helps you too. The original advice comes from this StackOverflow answer.
Difference between extend and include
Extend is used when a use case conditionally adds steps to another
first class use case. For example, imagine "Withdraw Cash" is a use
case of an ATM machine. "Assess Fee" would extend Withdraw Cash and
describe the conditional "extension point" that is instantiated when
the ATM user doesn't bank at the ATM's owning institution. Notice that
the basic "Withdraw Cash" use case stands on its own, without the
extension.
Include is used to extract use case fragments that are duplicated in
multiple use cases. The included use case cannot stand alone and the
original use case is not complete without the included one. This
should be used sparingly an only in cases where the duplication is
significant and exists by design (rather than by coincidence). For
example, the flow of events that occurs at the beginning of every ATM
use case (when the user puts in their ATM card, enters their PIN, and
is shown the main menu) would be a good candidate for an include.
Also, from every book I've read, it is always recommended to use include and extend sparingly. Keep It Simple Silly.
Many relationships are clearly not correct here. However, I think the main issue with this diagram is not the correct use of include and extend, but rather to complex and overall unclear relationships. Although sitactically valid, you should avoid using more than one level of these relationships.
Your diagram is really hard to follow and to interpret.
Some refactoring ideas and corrections:
show "Secure login" class separately, linked only with Actor and then apply the following precondition for all use cases that "include" it: "User is securelly logged in"
"Logout after 5 mins" should be own use case, only connected to Actor as well, with 2 preconditions: "User is securelly logged in" and "User was inactive for 5 mins"
Remove the include between "Logout after 5 mins" and "Initiate a call". Extend might be more appropriate
reverse the direcction of the include between "Transfer funds..." and "Insure adequate funds..." - it is clear that the first one includes the second one and not vice versa
consider breaking a diagram in 2 or more simple and small diagrams of only related UCs: all login/logout could for example be shown separate and simplify the view. You should not have more than 5-7 use cases on one diagram
guys how can I make conditions in use case diagram ? Something like decision node in activity diagram.
For example, If there is "evaluate" usecase which can lead either to Y or N, there is simply no way to express it. There is only constrain feature, that would lead to repeating { if evaluated } {if evaluated } ......
What you probably want to use is alternative paths, basically what you do is you repeat part of your use case like this:
In step 5, if there is not enough money on the account
5.a Show a message to the user
5.b User press "Try a lesser amount" button
5.c System goes to step 3
The Use Case Diagram doesn't seem to fit at all with conditions. Usually, when depicting multiple scenarios, one would make multiple use cases for each one. An activity diagram would be more fitting to display conditional logic.
Usually, conditions (IF) exist somewhere in the use case's activity that would cause the extended use case to occurs. You can add to extended use case to represent yes/no scenarios.