UML component diagram (2)

Purpose
Component Diagram
The main purpose is to display the structural relationship between system components. In UML 1.1
A component represents an implementation project, such as a file and a running program. Unfortunately, this is in conflict with the term component, which is more common and refers to something like a COM component. Over time and UML
Continuous version release, UML components have lost most of the original meaning. UML 2 has changed the essential meaning of the component concept.
The component is considered to be independent and provides one or more interfaces in the encapsulation unit of a system or subsystem. Although UML 2
The specification does not strictly declare it, but components are larger design units that present things. These things are generally implemented using replaceable components. However, it does not look like in UML 1.
X. Currently, components must have strict logic and are constructed during design. The main idea is that you can easily reuse and/or replace a different component implementation in your design, because a component encapsulates behavior and achieves
Specific interface. 1
In component-based development (CBD), component diagrams provide architects with a natural form of starting to model the solution. The component diagram allows an architect to verify that the required functions of the system are implemented by the component.
Ensures that the final system will be accepted.
In addition, component diagrams are useful communication tools for different groups. The diagram can be presented to the project initiators and implementers. Generally, when a component diagram connects system implementers
To make the project initiator feel relaxed, because the diagram shows an early understanding of the entire system to be created.
The developer finds that the component diagram is useful, because the component diagram provides them with a high-level architecture view of the system to be created, which will help developers start to build a road map for implementation, determine the task allocation and (or) Increase
Requirement skills. System Administrators find component diagrams useful because they can get an early view of logical software components that will run on their systems. Although the system administrator will not be able to identify physical devices or things from the graph
But they still welcome the component diagram because it provided earlier information about the component and its relationship (which promised the system administrator to easily plan the subsequent work ).
SymbolCurrently, the component diagram Symbol Set makes it one of the lightest and easy-to-draw UML diagrams. Figure 1 shows a UML 1.4
A simple component diagram of the symbol. This example shows the relationship between the two components: an order using the inventory system component
System component. As you can see, in UML 1.4, there is a large square with two protruding small blocks on the left to represent components.

Figure
1: This simple component diagram uses the UML 1.4 symbol to display the General dependency relationship of order system.
The above UML 1.4 symbols are still supported in UML 2. However, UML 1.4
Symbol sets cannot be well adjusted in large systems. The reason for this is that, as we will see in the rest of this article, UML 2
Significantly enhanced the symbol set of the component chart. While maintaining its ease of understanding, the UML 2 symbol can be better tuned and has more information.
Let's build a component diagram step by step according to the UML 2 Specification.
BasicNow, drawing a component in UML 2 is similar to drawing a class on a class diagram. In fact, in UML 2
A component is only an extraordinary version of the class concept. This means that the symbol rules applicable to classifier classes are also applicable to component classifiers. (If you have read and understood my previous general structure diagram and
Image-like details article [http: // www.
Ibm.com/developerworks/cn/rational/rationaledge/content/feb05/bell
/Index. shtml], you can easily understand the component diagram ).
In UML 2, a component is drawn as a vertical rectangle stacked with small pieces. UML 2
A high-level abstract view of a component, which can be modeled in a rectangle, including the component name and the text and/or icon of the component prototype. The component prototype text is "«component»", while the Group
The prototype icon is a large rectangle with two protruding small rectangles on the left (the symbol element of the component in UML 1.4 ). Figure 2 shows that the component can use UML
2. Representation of three different methods in the specification.

Figure 2: Different Methods for drawing component name Areas
When you draw a component in a diagram, it is important that you always include the component prototype text (the component in double angle brackets, as shown in 2) and/or icons. Why? In UML, a rectangle without any prototype classifier is interpreted as a Class component. The component prototype and/or icon are used to differentiate the rectangles used as component elements.
Provide/require interface modeling for componentsIn Figure 2
The order component shown in represents all valid symbol elements. However, a typical component diagram contains more information. An additional area can be attached to a component element under the name area. As mentioned above,
A component is an independent unit that provides one or more public interfaces. The provided interface represents the formal contract of the service provided by the component to its users/customers. Figure 3
It is displayed that the order component has a second partition to indicate the interfaces provided and required by the order component. 2

Figure 3: The additional area shows the interfaces provided and required by the order component.
In the order component example in figure 3, the component provides interfaces named orderentry and accountpayable. In addition, the component also requires another component to provide the person interface. 3Other modeling methods for component interfaces
UML 2 also introduces another method to display interfaces provided and required by components. This method is to create a large rectangle with the component name in it and place it outside the rectangle in the interface symbol in the UML 2 Specification. The second method is illustrated in figure 4.

4: An Alternative method (compared with figure 3): Use the interface symbol to display the interface that the component provides/requires

In the second method, a complete circular interface symbol at the end represents the interface provided by the component --
"Lollipop" is the stenographer of the relational symbols implemented by this interface classifier. The interface (also called socket) symbol with only half a circle at the end represents the interface required by the component (in either case, the interface name is placed in the interface character
). Even if figure 4 looks quite different from figure 3, both images provide the same information --
For example, the Order component provides two interfaces: orderentry and accountpayable, and the order componentRequirementsPerson interface.

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Purpose
The main purpose of a component diagram is to display the structural relationship between system components. In UML 1.1
A component represents an implementation project, such as a file and a running program. Unfortunately, this is in conflict with the term component, which is more common and refers to something like a COM component. Over time and UML
Continuous version release, UML components have lost most of the original meaning. UML 2 has changed the essential meaning of the component concept.
The component is considered to be independent and provides one or more interfaces in the encapsulation unit of a system or subsystem. Although UML 2
The specification does not strictly declare it, but components are larger design units that present things. These things are generally implemented using replaceable components. However, it does not look like in UML 1.
X. Currently, components must have strict logic and are constructed during design. The main idea is that you can easily reuse and/or replace a different component implementation in your design, because a component encapsulates behavior and achieves
Specific interface. 1
In component-based development (CBD), component diagrams provide architects with a natural form of starting to model the solution. The component diagram allows an architect to verify that the required functions of the system are implemented by the component.
Ensures that the final system will be accepted.
In addition, component diagrams are useful communication tools for different groups. The diagram can be presented to the project initiators and implementers. Generally, when a component diagram connects system implementers
To make the project initiator feel relaxed, because the diagram shows an early understanding of the entire system to be created.
The developer finds that the component diagram is useful, because the component diagram provides them with a high-level architecture view of the system to be created, which will help developers start to build a road map for implementation, determine the task allocation and (or) Increase
Requirement skills. System Administrators find component diagrams useful because they can get an early view of logical software components that will run on their systems. Although the system administrator will not be able to identify physical devices or things from the graph
But they still welcome the component diagram because it provided earlier information about the component and its relationship (which promised the system administrator to easily plan the subsequent work ).
SymbolCurrently, the component diagram Symbol Set makes it one of the lightest and easy-to-draw UML diagrams. Figure 1 shows a UML 1.4
A simple component diagram of the symbol. This example shows the relationship between the two components: an order using the inventory system component
System component. As you can see, in UML 1.4, there is a large square with two protruding small blocks on the left to represent components.

Figure
1: This simple component diagram uses the UML 1.4 symbol to display the General dependency relationship of order system.
The above UML 1.4 symbols are still supported in UML 2. However, UML 1.4
Symbol sets cannot be well adjusted in large systems. The reason for this is that, as we will see in the rest of this article, UML 2
Significantly enhanced the symbol set of the component chart. While maintaining its ease of understanding, the UML 2 symbol can be better tuned and has more information.
Let's build a component diagram step by step according to the UML 2 Specification.
BasicNow, drawing a component in UML 2 is similar to drawing a class on a class diagram. In fact, in UML 2
A component is only an extraordinary version of the class concept. This means that the symbol rules applicable to classifier classes are also applicable to component classifiers. (If you have read and understood my previous general structure diagram and
Image-like details article [http: // www.
Ibm.com/developerworks/cn/rational/rationaledge/content/feb05/bell
/Index.shtml], you can easily understand the component diagram ).
In UML 2, a component is drawn as a vertical rectangle stacked with small pieces. UML 2
A high-level abstract view of a component, which can be modeled in a rectangle, including the component name and the text and/or icon of the component prototype. The component prototype text is "«component»", while the Group
The prototype icon is a large rectangle with two protruding small rectangles on the left (the symbol element of the component in UML 1.4 ). Figure 2 shows that the component can use UML
2. Representation of three different methods in the specification.

Figure 2: Different Methods for drawing component name Areas

When you draw a component on the graph, it is important that you always include the component prototype text (the component in the double angle brackets, 2
And/or icon. Why? In UML, a rectangle without any prototype classifier is interpreted as a Class component. The component prototype and/or icon are used to differentiate the rectangles used as component elements.
Provide/require interface modeling for componentsIn Figure 2
The order component shown in represents all valid symbol elements. However, a typical component diagram contains more information. An additional area can be attached to a component element under the name area. As mentioned above,
A component is an independent unit that provides one or more public interfaces. The provided interface represents the formal contract of the service provided by the component to its users/customers. Figure 3
It is displayed that the order component has a second partition to indicate the interfaces provided and required by the order component. 2

Figure 3: The additional area shows the interfaces provided and required by the order component.
In the order component example in figure 3, the component provides interfaces named orderentry and accountpayable. In addition, the component also requires another component to provide the person interface. 3Other modeling methods for component interfaces
UML 2 also introduces another method to display interfaces provided and required by components. This method is to create a large rectangle with the component name in it and place it outside the rectangle in the interface symbol in the UML 2 Specification. The second method is illustrated in figure 4.

4:
An optional method (compared with figure 3): Use the interface symbol to display the interface that the component provides/requires
In the second method, a complete circular interface symbol at the end represents the interface provided by the component --
"Lollipop" is the stenographer of the relational symbols implemented by this interface classifier. The interface (also called socket) symbol with only half a circle at the end represents the interface required by the component (in either case, the interface name is placed in the interface character
). Even if figure 4 looks quite different from figure 3, both images provide the same information --
For example, the Order component provides two interfaces: orderentry and accountpayable, and the order componentRequirementsPerson interface.