Software Engineering

Topics: Unified Modeling Language, UML diagrams, Entity-relationship model Pages: 7 (1405 words) Published: March 9, 2013
Data flow diagrams illustrate how data is processed by a system in terms of inputs and outputs.Data flow diagram are used widely for modeling the requirements.the DFD is also known as a data flow graph or a bubble chart. Data Flow Diagram Notation

We can use two different types of notations on our data flow diagrams: Yourdon & Coad or Gane & Sarson. Process Notations
1) Process
A process transforms incoming data flow into outgoing data flow.

Yourdon and Coad Process Notations

Gane and Sarson Process Notation

2)Datastore Notations
Datastores are repositories of data in the system. They are sometimes also referred to as files.

Yourdon and Coad Datastore Notations

Gane and Sarson Datastore Notations

3)Dataflow Notations
Dataflows are pipelines through which packets of information flow. Label the arrows with the name of the data that moves through it.

4)External Entity Notations
External Entity
External entities are objects outside the system, with which the system communicates. External entities are sources and destinations of the system's inputs and outputs.

Entity–relationship model (ER model) in software engineering is an abstract way to describe a database. This article refers to the techniques proposed in Peter Chen's 1976 paper.An ER model is an abstract way to describe a database. There are three basic elements in ER models:

Entities are the "things" about which we seek information. Attributes are the data we collect about the entities.
Relationships provide the structure needed to draw information from multiple entities.

Symbols Used In ERD:

Object-oriented design is the process of planning a system of interacting objects for the purpose of solving a software problem. It is one approach to software design. An object contains encapsulated data and procedures grouped together to represent an entity. The 'object interface', how the object can be interacted with, is also defined. An object-oriented program is described by the interaction of these objects. Object-oriented design is the discipline of defining the objects and their interactions to solve a problem that was identified and documented during object-oriented analysis.

2. Automated Teller Machine (ATM)

A software to be developed for automated transactions. The system should be standalone in nature. It should be designed to provide functionality as explained:


Withdrawl the amount.
Cash take in any formet either 100 or 500.
More security provide.
Balance enquiry.
Slip of transaction.

2.b)Data Flow Diagram:




A use case diagram at its simplest is a representation of a user's interaction with the system and depicting the specifications of a use case. A use case diagram can portray the different types of users of a system and the various ways that they interact with the system.

Withdrawl use case discription:
1.Display a menu for transactions including withdraw cash with instructions to insert bankcard to begin the process. 2.Customer inserts the bankcard and a system verifies that the card is valid. 3.Systems prompt the customer to choose a language.

4.Customer chooses language.
5.System prompts the customer for pin number.
6.Customer enters pin number and submits data.
7.System verifies pin and displays an option for “Cash Withdrawal.” 8.Customer selects ”Cash Withdrawal.”
9.System prompts customer for “Amount to Withdraw.”
10.Customer enters amount and submits data.
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