Software Specification Tools

1. Software Specification Tools

2. What is structured analysis? • It focuses on specifying what the system or application is required to do. • Elements of structured analysis • Graphical description • Data Flow Diagrams • Data Dictionary: Definitions of elements in the system

3. What is structured Design? • Focus on the development of • software specifications

4. Data Dictionary: A data dictionary is a collection of descriptions of the data objects or items in a data model for the benefit of programmers and others who need to refer to them. A first step in analyzing a system of objects with which users interact is to identify each object and its relationship to other objects. This process is called data modeling and results in a picture of object relationships. After each data object or item is given a descriptive name, its relationship is described (or it becomes part of some structure that implicitly describes relationship), the type of data (such as text or image or binary value) is described, possible predefined values are listed, and a brief textual description is provided. This collection can be organized for reference into a book called a data dictionary.

5. Data Dictionary: • Data dictionary is a main method for analyzing the data flows and data stores of data-oriented systems. • The data dictionary is a reference work of data about data (metadata). • It collects, coordinates, and confirms what a specific data term means to different people in the organization.

6. Reasons for Using a Data Dictionary: • Provide documentation. • Eliminate redundancy. • Validate the data flow diagram. • Provide a starting point for developing screens and reports. • To develop the logic for DFD processes.

7. The Repository: • A data repository is a large collection of project information. • It includes: • Information about system data. • Procedural logic. • Screen and report design. • Relationships between entries. • Project requirements and deliverables. • Project management information.

8. Data Dictionary Contents: • Data dictionaries contain: • Data flow. • Data structures. • Elements. • Data stores.

9. Defining Data Flow: • Each data flow should be defined with descriptive information and its composite structure or elements. • Include the following information: • ID - identification number. • Label, the text that should appear on the diagram. • A general description of the data flow.

10. Defining Data Structures: • Data structures are a group of smaller structures and elements. • An algebraic notation is used to represent the data structure.

11. Defining Elements • Data elements should be defined with descriptive information, length and type of data information, validation criteria, and default values. • Each element should be defined once in the data dictionary.

12. Defining Elements – Format: • Input and output formats should be included, using coding symbols: • Z - Zero suppress. • 9 – Number. • X – Character. • X(8) - 8 characters. • . , - Comma, decimal point, hyphen. • These may translate into masks used to define database fields.

13. Using a Data Dictionary: Database applications can be made much simpler if you maintain a body of data that describes your tables. Every single programming task in a database application needs to know something about the tables it is working with, so every program in a framework and many programs in an application can benefit from a central store of information about the database. Introducing the Data Dictionary: The term "data dictionary" is used by many, including myself, to denote a separate set of tables that describes the application tables. The Data Dictionary contains such information as column names, types, and sizes, but also descriptive information such as titles, captions, primary keys, foreign keys, and hints to the user interface about how to display the field.