Component Diagram

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Session

Component Diagram

Checklist

Introduction to Component Diagram

Elements of Component Diagram

Construct Component Diagram for Case Study

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Component Diagram

Physical implementation of a system should address three primarily problems, they are

Software, Hardware and the interaction between them. Component Diagram are used to

represent physical implementation of the software design whereas physical architecture of the

system is represented using deployment diagrams. Combine them both you can see your

application software running across your hardware. Session 7 details about Deployment

Diagrams.

Consider each component as a bunch of code running on a physical piece of hardware. Each

component should provide interfaces to be serviced by other components of the software

design. The logical implementation are done by the classes that are encapsulated within the

component.

Components can be grouped into three categories

Deployment Components – Components which are required to run a system

Work product Components – Components which produce Deployment components

Execution Components – Components created while running the application.

Elements of Component diagrams?

Elements of component diagram are not much different than what we have seen in class

diagram and composite structure diagram. UML 2 has a notation to represent component

diagram as shown in the figure below. Just Add () to a class or <<component>> stereotype to a

class.

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Figure 1: Component Notation

Component Stereotype

Components stereotype provides visual cues about roles played by components in a system.

Some of component stereotype are as follows.

Figure 2: Component Stereotype

Constructing Component Diagram for our Case Study

Problem Statement

We are going to use Coffee Vending Machine for our case study. This is the coffee machine that

are used in coffee shops that are operated by store’s worker. Operator can select the type of

coffee and our system provides one by mixing correct portions of milk, water and flavor.

Operator can cancel the order at any time and the system would stop preparing coffee. Our

system gives status information to the operator too. Figure below shows the component

diagram of Coffee Vending Machine.

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Solution

Our system has two layers; Application Layer and Middleware Layer. Let us look at the

components and the functionality they provide for the system.

Table 1: Component Diagram Functionalities

Components Functionality

Application Layer

UI

Handles what to be displayed on the screen. It is an executable. It requires services from Process Order and State Machine to update the display accordingly

Process Order

Core functionality of coffee making part is handled here. It is an executable. It updates the state machine and talks with lower layers of the system to prepare coffee.

State Machine

Maintains the state of the system. Gets input from status manager for status change events from hardware or from the operator

Middleware Layer

Status Manager

Status Manager uses IPC mechanism and stands a medium of communication between Application layer and Middleware layer. It interacts with Interrupt Handler and Tank Manager.

Interrupt Handler

Handles external interrupts to the system. For Example when system losses it power or when the operator cancels the order. When such events occur Interrupt Handler informs the status manager so that application layer components knows about the event.

Tank Manager

It communicates with library files to update the status manager about our Vending machines tank status. For Example: If Water tank is empty WaterTank.a presents event notification to TankManager. TankManager then validates the event and updates the StatusManager

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Figure 3: Component Diagram (Case Study)

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Review

Component Diagram is used to represent physical implementation

of a software design

Components can be grouped as Deployment Component, Work

Product Component and Execution Component

Component states provide visual cue to the function of the component