Home / BA / Use Case Relationships

Use Case Relationships

Usecase diagram is drawn to explain the different ways that a user might interact with the system boundary, they gather requirements of a system depending on requirement we can use data in different ways. Generally in use-case diagrams consist of Actor, use case, system. The actor is an entity that performs a role in the given system this could be a person or organization. Usecase represents an action within the system which explains the purpose of the actor,  use-cases are the system functionalities that will be designed in the systematic method. the system acts like a system boundary that will create all the use-cases.

Coming to the relationship of use case diagrams we can see few interactions between actors, use-cases where

Actor association with a use-case where the actor must associate at least with one use-case as default.No actor is involved without any kind of association with use-case or with other actors. one actor can associate with multiple use cases and multiple actors can associate with a single use-case.

Ex: while accessing a bank account, the customer can open an Account or he can deposit funds to his account where bank employees will also have access to the account opening so here customer and bank employee were the actors, and opening account and deposit funds is the use-case.

Actor generalization where in this actor generalization actor inherits the role of other actors, If any two actors having some similar use-cases in they job role then to colloid their similarities between two actors we use actor generalization. In this one actor represents the arrow towards the other similarly inherited actor.

Ex: When representing customers in the bank system we can easily find different kinds of customers with some similarities and with some differences in their account privilege where Basic account customers and NRI account customers are having different use-cases with few common basic similarities so here to represent that similarities we use actor generalization.

Extend Relationship between two use-cases Here in extend relationship we have to remember that an extended relationship is only used for optional things between the two use-cases, it should be independent and must not rely on any other extending use case. Extending the use case is optional and it is not a must.

EX: If bank having condition as interest amount will be generated only if the customer maintains at least one lakh in savings account so in this case, not all the customers having this option so we use to extend the relationship to intimate the eligibility to the customers with condition.

Include the relationship between two usecases Inthis relationship we can easily say Include relationship is mandatory and not optional, the base usecase is incomplete without the include usecase.include relationship can be attached to many usecases depending on the extension of the role.

Ex: If the customer wants to withdraw money in the ATM then he must have login details aswell as same with checking only account balance  where in this situation we can say login usecase is mandatory to extend the process and without this login usecase customer couldn’t process his transaction so here we consider login as include the relationship with money withdraw and checking account balance.

Generalization with use-case This relationship plays the common behavior between two usecases with specific behavior to each usecase this is similar to generalization of an actor, In common words when a useacase represent several actions and should outcome with one specific usecase as a result.

Ex: As in banking portal customer can pay his bills so in this condition customer can use multiple methods to complete payment transaction like through net-banking,UPI, cheque where all these payment methods come as generalization use-cases where customer can select any of the method to complete the transaction process.

In the Usecase diagram we connect actors,usecases, systems with the below lines:

  • Communication line
  • Includes line
  • Extends line
  • Generalization line

The communication line is the line drawn between the actor and the system where it denotes a normal link between the actor and the system, communication line is just to show the purpose of the actors with the system boundary where it is having no direction arrow.

Design of communication line:  ——————–

Includes line is the relationship used when there is a must option to go through, when we use Include relationship then the process should satisfy the given condition. Includes line can be connected to many functionalities depending upon the must conditions where the Include relationship line looks like arrow forwarding towards the common usecase.

Design of Includes line:     <——————–

Extend line is the relationship used when there is an option to go through, It is not a must condition. when we use extend relationship line the process may or may not satisfy the given conditions, extend line can be connected to many functionalities depending upon the given conditions where this extended relationship line looks like an arrow forwarding towards the extend condition from the common use case functionality.

Design of Extend line:       ——————–>

The generalization line is the relationship used when the user is having a choice with the functionalities like when the customer is paying payment then he can complete the transaction either with a card, cash, cheque,UPI…etc. generalization relationship line can be drawn between the users to users and between two use cases. This relationship line looks like a common straight line.

Design of generalization  line:    ——————–

About Atchakolu shyam narayana chakravarthy

Check Also

Q1. What is BRD? How it is different from SRS?

BRD BRD stands for Business Requirement Document. It is a formal document that specifies all …

Leave a Reply

Watch Dragon ball super