The complete guide to use case: creation and application

The complete guide to use case: creation and application

Let's look at what a use case is, figure out how to use it, and how to create scripts correctly for effective product analysis and development.

The complete guide to use case: creation and application

Let's look at what a use case is, figure out how to use it, and how to create scripts correctly for effective product analysis and development.

Use Case in simple words

1. Title. Short and clear. Describes what the user is doing. For example, ordering a product.
2. Actors. People who are in contact with the system. For example, a customer.
3. Preconditions. What needs to be done before the script starts. For example, a customer logged in.
4. The main stream. The steps that the user takes to achieve his goal. For example:

• the buyer chooses the product;
• The product is added to the cart by the customer;
• the buyer places an order.

1. Alternative streams. Additional options are available to the user for selection. For example, if the item is unavailable:

• the buyer receives a notification of a shortage of goods;

• The buyer can choose another product or return it later.

2. following conditions. The outcomes must be attained once the scenario is finished. For instance, the buyer has gotten a confirmation after an order has been created.

Stages of Writing a Use Case

In software development, the use case shows how the user applies the system to achieve their goal. This helps you understand what the system needs and how it should work. Let's look at the main stages of writing a use case.

1/ Define the boundaries of the system

First, decide which functions and processes will be inside the system and which will not. This will help you focus on what is important to users.

2/ Find the actors

Actors are those who will interact with the system: users, and administrators. List all the actors.

3/ Define the goals

For each factor, define its goals or objectives. This is what he wants to do with the system. For example, create an account or buy an item. State these goals clearly.

4/ Describe the scenarios

For each actor, describe how it interacts with the system in the use case. A scenario is a set of actions that must be taken to accomplish a task. Describe the main and alternative scenarios that show different options for action.

5/ Identify the prerequisites and postconditions

Indicate which requirements need to be met both before the scenario begins (prerequisites) and after it is finished (postconditions). This will help to establish the right context.

6/ Describe the steps in detail

Describe each step in detail. Specify what the actor is doing and how the system reacts. The description should be accurate and consistent so that everyone understands how the system should work.

7/ Check and confirm

After writing the script, discuss it with other project participants. Check if the script is logical and if you haven't missed something important. This will help ensure that the use case reflects the real needs of users.

8/ Document and maintain

Write down the use case in a convenient format and make it available to all project participants. Update the use case regularly to keep it up to date with current changes in the system.

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Recommendations for Writing a Use Case

✅ Use simple language. Avoid complicated terms and technical details. Write so that anyone can understand the script.

✅ Focus on the user. Always remember that you are describing the user's actions and needs. This helps to create a scenario that really reflects the actual operation of the system.

✅Be specific. Avoid common phrases and vague descriptions. Specify exactly what the user does and when.

✅ Optimize the structure. Divide the scenario into logical parts: purpose, actions, system reaction, and alternatives. This will improve the perception of information.

✅Check and clarify. Ask colleagues or users to check the written use case. Their comments will help clarify and improve the scenario.

Use Case Usage Models

Typically, models are diagrams that show the interaction between users and the system.

The main elements of the diagram:

1. The actor. the person utilizing your system to communicate.
2. System. The software or application that the actor interacts with.
3. Use Case. An action or series of actions that an actor performs to achieve his goal.
4. Communications. Lines that show the interaction between the actor and the use case.

Imagine that you are developing an application for online pizza ordering. Let us examine "Ordering pizza" as one of the potential scenarios.

User Steps:

1. Opens the application.
2. Select the "Pizza" category.
3. Select a specific pizza from the list.
4. Add pizza to the cart.
5. Goes to the shopping cart and confirms the order.
6. Enters the data for delivery.
7. Confirm the payment.

Use case usage diagram:

The complete guide to use case: creation and application

Example of a Text-based Use Case

Title: Ordering a taxi through a mobile application.

User Role: Passenger.

The main scenario

Step	The actor	Action
1.	Passenger	Opens the mobile app
2.	System	Loads the main page with the map
3.	Passenger	Enters the destination address
4.	System	Displays the entered address on the map
5.	Passenger	Select the type of car
6.	System	Displays the cost of the trip
7.	Passenger	Presses the "Order" button
8.	System	Starts searching for a free car
9.	Passenger	Tracks the movement of the car on the map
10.	System	Displays information about the accepted order
11.	Passenger	He gets into a taxi
12.	System	Charges the payment after the trip
13.	Passenger	Leaves a rating and a review
14.	System	Saves the rating and review in the database

The passenger successfully orders a taxi through the app, gets to their destination, and leaves an assessment of the quality of service.

Alternative scenarios

Cancellation of the order

Step	The actor	Action
1.	Passenger	Cancels the order through the app
2.	System	Confirms the cancellation and informs about possible penalties

Changing the destination

Step	The actor	Action
1.	Passenger	Changes the destination during the trip
2.	System	Recalculates the cost of the trip and informs the driver

This format shows what the user is doing and what the system is doing at each step of the taxi ordering process.

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The Use of the Use Case

Who needs a Use Case

✅For developers. Programmers use cases to create and test software. It helps them see which features need to be implemented and how users will interact with the product.

✅To the analysts. Business analysts use cases to identify product requirements. It helps to understand the needs of customers and formulate tasks for developers based on them.

✅To project managers. Project managers use cases to plan and control work. It helps to track progress and make sure that the product meets customer expectations.

✅ For users. End users are often involved in the development of a use case: they know their needs best and can provide valuable information on how they will use the product.
Where the Use Case is needed

✅ In IT. Software development companies actively use use cases at all stages of development — from planning to testing.

✅ In startups. New companies and projects often use cases to develop a product that meets market requirements quickly and accurately.

✅ In large corporations. Large companies with different products and services use cases to improve processes and meet customer needs.
When you need a Use Case

✅ At the planning stage. At the very beginning of the project, the use case helps to determine what functions and tasks the product should perform. The foundation for more effort is this.

✅ In the process of development. Developers and testers are constantly turning to use cases to make sure they are moving in the right direction and haven't missed important details.

✅ During testing. Use case helps to check how the product works in real conditions. Testers use it to create scenarios, test, and identify errors.

✅ After the product launch. Even after the product is released to the market, the use case remains useful. It helps to maintain and update the product and add new features.

What are the limitations of the Use Case?

Use case is a method of describing system requirements that helps to understand what users want to do with the program. It is useful, but it has its limitations. Let's figure out which ones.

🔺 Insufficient detail. Use case describes actions at a high level, and often omits details. This can confuse developers and users, and they will face difficulties in implementing the requirements.

🔺 Problems with describing alternative events. Use case works well for predictable user actions, but does not take into account system errors, unexpected data inputs, or external influences. For such cases, additional description methods are needed.

🔺 Difficulties with modeling complex interactions. When systems become complex, the use case may not be able to handle describing all the interactions between components. This can lead to a simplification of the model, which does not always reflect the actual operation of the system.

🔺 An inconvenience for describing non-functional requirements. The use case focuses on what the system should do but does not take into account aspects such as performance, security, and usability. This can lead to ignoring important system characteristics.

🔺 Difficulties in support and updating. In large projects, it is difficult to keep the use case up-to-date. Due to changes in requirements or the system, it is often necessary to revise and rewrite the use case - this takes a lot of time and effort.

🔺 Dependence on the author's experience. The quality of use cases depends on the experience of the person who writes them. An inexperienced analyst may miss important details or misunderstand requirements — this will lead to the creation of incorrect scenarios.

The main thing about the Use of Case

🟣 The use case explains how the user works with the system step by step to achieve a specific goal. These cases show how actors use the system to achieve goals and help make development more tailored to their needs.

🟣When writing a use case, it is important to outline the system's boundaries, find actors, set their goals, describe the interaction scenario, identify prerequisites and postconditions, describe the steps, check and confirm the scenario, and maintain its relevance.

🟣 Use case models and diagrams are tools for developing user—friendly and functional applications. They help to better understand the user's interaction with the system, identify important functional requirements, and avoid mistakes at the development stage.

🟣 Use case helps developers, analysts, managers, and users work together to create a high-quality product. It is important to apply the use case at all stages of development. Understanding this concept will make the work efficient and meet the needs of customers.

🟣 Use Case is a useful tool, but it has limitations: it does not always provide enough details, does not cope well with unexpected events and complex interactions, and does not describe non-functional requirements. To get a complete and accurate understanding of the system and requirements, you must use case and other methods.