Unified Modeling Language is an industry-standard graphical language that serves as a blueprint for software developers to model the structure of a software system. It helps them understand, design, and document the structure and behavior of a software system.
During the early stages of the software development cycle, UML structure diagrams assist software developers in the design process. These diagrams also help present the software's architectural structure to the concerned stakeholders. This allows developers to model the software system as per the requirements of the client.
In this article
What is Structural UML Diagram?
Structural UML diagrams are used to visualize the static behavior of a software system. They also help us understand the structure as well as the relationship among various components within the software system. These diagrams also serve as a blueprint for maintaining and managing the software system.
The diagrams are a crucial tool when defining the requirements of a software system. Developers can use these diagrams to effectively get feedback from stakeholders. This ensures that the software being developed is per the requirements of the client thus resulting in better risk management at an early stage of the software development.
Types of UML Structure Diagram
1. Deployment Diagram
A deployment diagram is a type of structural diagram that depicts how software is deployed over hardware nodes. These diagrams help us model the physical aspects of object-oriented systems. Software developers can use this diagram to depict where software is deployed over a node. This helps in better management of the system.
The above deployment diagram is for a 3-tier client-server architecture. Here the system's hardware components are represented using nodes whereas the software component uses artifacts. Within this architecture, the request made by a client is processed on the application server and then taken to the database system.
2. Package Diagram
An UML package diagram is a type of UML (Unified Modeling Language) that groups related elements within the system into packages. A package may include classes, interfaces, artifacts, nodes, and diagrams. A package diagram can depict the structure and the dependency among various elements or modules, offering a better view of the system.
The above package diagram illustrates the workings of a hospital management system. It depicts various operations and individuals involved in the form of packages. It also describes how different components access or import resources from other packages and how they interact.
3. Class Diagram
A class diagram is a structured diagram that serves as a blueprint to represent the structure and the relationship among classes within a software system. It depicts a static view of the system by showing its classes, attributes, methods, and relationships among the classes.
The above class diagram is for a hospital management system. It depicts the static image of the various components involved in the system. The diagram illustrates how various daily operations are carried out within the hospital system and how various entities and departments work together to achieve the system's overall functionality.
4. Object Diagram
An object diagram is a type of UML (Unified Modeling Language) that represents an instance of a class. These diagrams present the static view of the system at a point in time and also the relationship among the objects. The concept behind object diagrams is derived from OOP where an object is an instance of a class at a point in time. In other words, an object diagram is derived from a class diagram.
The above object diagram depicts the internal workings of the central processing unit. It illustrates how different components interact to provide the desired output for a specific input. The diagram shows the system's working at a particular point in time.
5. Composite Structure Diagram
A composite structure is a type of structured diagram that gives an overview of the internal structure of an entity or components. It helps in understanding the relationship among the components within the software system. The diagram is similar to a class diagram but provides a more detailed view of the internal components within classes. It also helps in understanding how these components interact with one another.
The above composite structure diagram shows the internal workings of a car system. More specifically, it illustrates the workings of the braking, acceleration, and steering system. Inside a particular system, multiple parts work together to achieve the functionality of the system.
6. Component Diagram
A component diagram provides a static view of the components that make up a system. It breaks down a large software system into smaller parts. This makes it easier to understand how the software system works. The diagram also helps us understand the dependency among the components. That is if a change to a certain component is made how will it affect the other components?
Above is a component diagram for the library management system. It splits the working of the management system into various smaller parts, called components. The diagram illustrates how different components interact to ensure that the process of issuing books is properly managed within the system.
Benefits of Using Structural UML Diagram
The various benefits of using a UML structural diagram include:
- Structural diagram provides a clear view of the system architecture and how various components are connected.
- A structural diagram helps in better collaboration among team members. It also helps in communication with the stakeholders to provide them with an overview of the software system being developed.
- Structural diagram provides a static view of the software system being developed. This helps developers to better plan the requirements of a software system.
- Structural diagrams promote module-based software development. This ensures better management and understanding of the software system.
- The use of structural diagrams allows developers to better manage the resources related to software development.
- Through structured diagram we get a clear visualization of how various components are connected within the software system. This results in better and timely management of an issue if occurred.
- The use of a structured diagram promotes consistency by ensuring that all the stakeholders follow the same design principles.
Challenges Faced in Developing Structural UML Diagram
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Choosing the Right Diagram
Different systems have different requirements. Choosing the right diagram to map the system requirements is extremely important. The software developer must pay close attention to choosing the right diagram to design their software system.
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Mapping of Requirements
When creating a structural diagram, the first problem faced by system designers is how to map the requirements of the system to a diagram. Here the software developer first needs to analyze the architecture of the system, then map the requirements to a structured diagram.
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Updating Changes
The design of a system may change over time as a result of changes in requirements. Here mapping the existing design to the changes made in the system becomes a problem for an organization. Also making the design consistent across the board poses a challenge for an organization.
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Knowledge of Tools
When designing a structural diagram proficient knowledge of the tools is required. The designer not only needs to know the system architecture but also the tools that design the architecture of a software system.
Tips for Developing a Behavioral Diagram
Drawing of behavioral diagram involves identifying and modeling concepts in a particular system to illustrate the interaction and behavior of components. Here�s a concise guide to help you develop a clear and effective behavioral diagram:
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Identify the Actors
The process begins with determining who or what is interacting. They could be other users, elements of a system, or any other factor that impacts your system.
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Define the Behaviors
Provide all the behaviors or actions through which these actors can interact with the system. When writing down the behaviors, ensure that each one is unique from the other to avoid confusion.
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Determine the Interactions
Explain who does what in the system and whether these actors work together, in parallel, sequentially, or independently. Write down the action sequences and the corresponding reactions associated with them.
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Use Simple Symbols
Elements should be presented using their equivalent standard symbols. Arrows could also give clues as to the direction of interaction and rectangular shapes may depict different states or operations.
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Review and Refine
Remember to compare your diagram with your expectations to make sure that all the details that you have included are accurate as well as clearly illustrated.
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Keep It Simple
Emphasizes writing in simple language. Do not add too many details altogether in your diagram. This may confuse the viewer.
Conclusion
In short, creating a structural UML diagram is important when portraying the structure of the system and the relation between various entities present within a project. They represent a static blueprint, which helps in understanding the architecture and inner workings of the system.
These diagrams enhance the overall cooperation among the members of a team and also help in conveying the design details to the clients and other stakeholders. Before you design your system it's important to understand the requirements of the system. This will help you to better choose the diagram to design your system.
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