29-06-2012, 05:07 PM
Data and Process Modeling
Data and Process Modeling.ppt (Size: 384 KB / Downloads: 44)
Today’s Buzzwords
Data Modeling
Process Modeling
Data Flow Diagrams
Entity-Relationship Models
Cardinality and Participation Constraints
Weak Entities
Generalization Hierarchies
Objectives of this lecture
Describe the process inherent in a system
Present a system process in a concise diagrammatic form
Describe the system data in terms of conceptual objects and relationships between them
Translate such conceptual descriptions into actual tables
Benefits of Conceptual Design
Projects without a strong conceptual design are more likely to fail
Design is one of the most important aspects of project and business process quality management standards:
ISO 9000
CMM
Designs are typically network structured, not flat like databases
Literature in Relational Model shows Benefits of Conceptual Design in user performance
Database Modeling
Process Models
Overview of process components
Inputs and outputs of different processes
Data sources and destinations
Mode of data flow between processes
Data Models
Model only the data, no process
Different components of the data
Relationships between primary data components
Models, method, and media
A model
describes business or organization
separates operation from technology
Good modeling requires good methodologies
encompass data, process, decisions
richly expressive and provide for levels of analysis
simple representation
Modeling medium
both formal and visual
DFD rules
Start with a very basic overview of complete process, showing only the most important processes, sources, destinations, and files
Recursively “explode” each of the processes (note: processes only!):
preserve inputs and outputs
preserve file accesses
new processes, files and sources/destinations can be created, but cannot be used from previous levels if not directly used in the previous level
Overview of Data Modeling
Conceptual design: (ER Model is used at this stage.)
What are the entities and relationships in the enterprise?
What information about these entities and relationships should we store in the database?
What are the integrity constraints or business rules that hold?
A database `schema’ in the ER Model can be represented pictorially (ER diagrams).
Can map an ER diagram into a relational schema.