CHAPTER 8 Analysis Modeling

CHAPTER 8

8.1 Data Modeling

Data modeling is very important part of the analysis it mainly deals with the data object and their relationship. With the help of data model one can easily identify the primary objects to be process by the system. Data model makes Entity-Relationship (ER) diagram to describe the relationship between entities. The data model considers the data independent of the processing that transform the data.

8.1.1 Data Objects and Attributes

The data model consists the data objects and attributes that describe the data object. A data object is the representation of any composite information that is processed by computer software. A data object can be an external entity, a thing, an occurrence or event, a role, a structure etc. A data object encapsulates the data only-there is no reference within a data object to operations that act on the data. So the data object can be a table.

Attributes define the properties of a data object and take on one of three different characteristics.

1. Name an instance of the data object

2. Describe the instance

3. Make reference to another instance in another table.

Also one or more attribute can be defined as identifier i.e.- Key. The key is used to make the relationship with the attribute of another data object. It may or may not be unique. In our context, we can say that as our project is RDBMS, so here relationship between various data object is essential to get required information and result the user want. So key has very important role here to make references as well as referential integrity and to prevent from data redundancy.

8.1.2 Cardinality and Modality

Cardinality: Cardinality defines the maximum number of objects that can be participating in a relationship. According to Tillmann, the cardinality is the specification of the number of occurrences of one object that can be related to the number of occurrences of another object. Taking into consideration all combinations of ‘one’ and ‘many’ two objects can be related as:

1 One-to-One (1:1)

2 One-to-Many (1:M)

3 Many-to-One (M:1)

4 Many-to-Many (M:N)

Modality: Modality normally says that whether the occurrence of a relationship is necessary or not. The modality of a relationship is 0 if there is no explicit need for the relationship to occur or the relationship is optional and 1 if the occurrence of the relationship is mandatory.

8.1.3 Entity Relationship Diagram

The Entity Relationship Diagrams (ERD) is the graphical notation of relationship between data object and attributes. The ERD was originally proposed by Peter Chen for the design of relational database systems and has been extended by others. Sets of primary components are identified for the ERD: data objects, attributes, relationship, and various type indicators. The primary purpose of the ERD is to represent data objects and their relationship.

The ER diagram for “TRANS SERVICE NET”

Analysis (DFD’S, E-R Diagram, Class Diagrams):

DATA FLOW DIAGRAM:

0 LEVEL D.F.D.:-

This is the context level D.F.D. of the proposed system the whole system has been depicted in a single bubble, primary input and output has been carefully noted and depicted in the way so that information flow continuity should not be lost in the next level. The proposed system is shown as a whole process and the inputs and outputs are shown with incoming and outgoing arrow from the

payment_mast: Table

payment_det: Table

cust_det :Table

street_mast:Table

city_mast :Table

route_mast:Table

route_det:Table

trans_tranc_details :Table

A Complete Structure of the Program

8.2 Functional Modeling

The functional model shows how output values in a computation are derived from input values without regard for the order in which the values are computed. The functional model consists of multiple data flow diagrams, which show the flow of values from external inputs, through operation and internal data stores, to external output.

8.2.1 Data Flow Diagram

The Data Flow Diagram is the graphical representation that depicts information flow and the transforms that are applied as data move from input to output. DFD is a model, which gives the insight into the information domain and functional domain at the same time. DFD is refined into different levels. The more refined DFD is, more details of the system are incorporated. In the process of creating a DFD, we decompose the system into different functional subsystems. The DFD refinement results in a corresponding refinement of data. After going through the current working process of the department, we can create the Data Flow Diagram