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Session

Package Diagram

Checklist

Introduction to Package diagram

Explain Package diagram notations

Construct Package diagram for our Case Study

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Package Diagram

Package diagrams are used to structure high level systems. Packages are used for organizing

large system which contains diagrams, documents and other key deliverables. Packages are

used as constructs, they can hold class diagrams or other forms of UML diagrams that we have

seen so far. Packages can be used as a part of other diagrams also.

Package diagram follows hierarchal structure of nested packages. Atomic module for nested

package are usually class diagrams. There are few constraints while using package diagrams,

they are as follows.

Package name should not be the same for a system, however classes inside different

packages could have the same name. For Example, Package::Product &

Shipping::Product are allowed.

Users should not use package name delivered by the programming language. For

Example, Java provides Date as a package. So, programmers should construct package

with name Date.

Packages can include whole diagrams, name of components alone or no components at

all.

Fully qualified name of a package has the following syntax

Name owing the package :: Name of the package

Java :: util :: Date

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There are only two elements for a package diagram - packages and dependencies.

Elements of a Package Diagram

Package Notation

Packages can be represented by the following notations.

Figure 1: Package notations

Dependency Notation

There are two sub-types involved in dependency. They are <<access>> & <<import>>. Though

there are two stereotypes users can use their own stereotype to represent the type of

dependency between two packages.

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<<import>> - one package imports the functionality of other package

Figure 2: <<import>> dependency

<<access>> - one package requires help from functions of other package.

Figure 3: <<access>> dependency

Constructing package diagram for our Case Study

The Problem Statement

We are going to design package diagram for “Track Order” scenario for an online shopping

store. Track Order module is responsible for providing tracking information for the products

ordered by customers. Customer types in the tracking serial number, Track Order modules

refers the system and updates the current shipping status to the customer.

Step 1 Identify the packages present in the system

There is a track order module, it has to talk with other module to know about the order

details, let us call it “Order Details”.

Next after fetching Order Details it has to know about shipping details, let us call that as

“Shipping”.

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Finally if knows the status of the order it has to update the information to the user, let

us call this module as “UI Framework”.

Figure 4: Identifying the packages

Step 2 Identify the dependencies

Track order should get order details from

“Order Details” and “Order Details” has to

know the tracking info given by the customer.

Two modules are accessing each other which

suffices <<access>> dual dependency

To know shipping information, “Shipping” can

import “Track Order” to make its life easier.

Figure 6: Step 2b - Identifying dependencies

Figure 5: Step 2a - Identifying dependency

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Finally, Track Order dependency to UI Framework is also mapped which completes our

Package Diagram for Track Order subsystem.

Figure 7: Track Order Package Diagram

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Review

Package diagram is used to show high level view of a system

Package diagram can be used in any UML diagram and can hold

UML diagrams

Elements of Package diagram – Package notation and dependency