Use case diagram is a behavioral UML diagram type and commonly used to analyze various systems. They allow you to visualize the different types of duties in a system and how those roles connect with the system. This use situation diagram tutorial will cover the complying with topics and aid you create use cases better.

You are watching: The line from the actor to the use case is called a(n) _____.

How to create use situation diagrams ( with example )

Importance the Use case Diagrams

As mentioned prior to use instance diagrams are offered to gather a consumption requirement that a system. Depending on your need you have the right to use the data in various ways. Listed below are couple of ways to use them.

To identify functions and how roles interact with them – The main purpose of use instance diagrams.For a high-level view of the system – Especially valuable when presenting to managers or stakeholders. You have the right to highlight the roles that interact with the system and the functionality listed by the device without going deep right into inner functions of the system.To recognize internal and external factors – This might sound basic but in large complex projects a system deserve to be established as an external role in one more use case.

Use case Diagram objects

Use case diagrams consists 4 objects.

ActorUse caseSystemPackage

The objects are further defined below.


Actor in a use instance diagram is any reality that performs a role in one given system. This could be a person, organization or an external system and also usually attracted like skeleton displayed below.


Use case Diagram Guidelines

Although use case diagrams deserve to be supplied for miscellaneous purposes there space some common guidelines you must follow when drawing use cases.

These incorporate naming standards, direction of arrows, the placing of usage cases, intake of mechanism boxes and likewise proper usage of relationships.

We’ve covered these indict in detail in a different blog post. So go ahead and also check the end use case diagram guidelines.

Relationships in Use situation Diagrams

There room five varieties of relationship in a use situation diagram. Castle are

Association in between an actor and also a usage caseGeneralization of one actorExtend relationship between two use casesInclude relationship in between two use casesGeneralization that a use case

We have actually covered all these relationship in a separate blog post that has examples with images. We will not go into information in this article but friend can inspect out relationships in use case diagrams.

How to produce a Use situation Diagram

Up to now, you’ve learned about objects, relationships and also guidelines that are an important when illustration use instance diagrams. I’ll explain the assorted processes utilizing a banking device as an example.

Identifying Actors

Actors are outside entities that communicate with your system. It have the right to be a person, one more system or an organization. In a bank system, the most evident actor is the customer. Various other actors can be bank employee or cashier depending on the function you’re trying to show in the use case.

An example of an external organization have the right to be the taxes authority or the central bank. The loan processor is a good example of an exterior system associated as an actor.

Identifying use Cases

Now it’s time to determine the use cases. A an excellent way to perform this is to recognize what the actors require from the system. In a banking system, a client will need to open accounts, deposit and also withdraw funds, request check publications and similar functions. So every one of these have the right to be taken into consideration as usage cases.

Top level use instances should always carry out a complete role required by one actor. Friend can prolong or include use cases depending ~ above the intricacy of the system.

Once you recognize the actors and the top level use situation you have a an easy idea that the system. Now you can fine tune it and add extra class of detail to it.

Look for usual Functionality to use Include

Look for common functionality that have the right to be reused across the system. If you discover two or much more use situations that share usual functionality you can extract the usual functions and include it come a different use case. Climate you can connect it via the encompass relationship to display that it’s always called when the initial use situation is executed. ( watch the chart for an example ).

Is it possible to Generalize Actors and also Use Cases

There might be instances whereby actors are associated with similar use situations while triggering a couple of use situations unique only to them. In such instances, you can generalize the actor to present the inheritance of functions. You have the right to do a comparable thing because that use situation as well.

One of the best examples the this is “Make Payment” use instance in a payment system. You can more generalize it come “Pay by credit Card”, “Pay by Cash”, “Pay by Check” etc. Every one of them have the attributes and also the usability of payment with special scenarios distinctive to them.

Optional functions or added Functions

There room some attributes that are triggered optionally. In together cases, you have the right to use the extend relationship and also attach one extension preeminence to it. In the below banking system example “Calculate Bonus” is optional and also only triggers when a certain condition is matched.

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Extend doesn’t always mean it’s optional. Sometimes the usage case linked by expanding can complement the base usage case. The thing to mental is the the base use instance should be able to perform a role on the own also if the expanding use situation is no called.