Modeling and Evaluation

Modeling Information system model –User perspective of data elements and functions –Use case scenarios or diagrams Entity model –ER Diagrams –UML class diagrams Transaction model –Processes and transactions the user sees –Inputs, outputs, and manipulations

Additional documentation Data dictionary –Listing of tables, columns, datatypes, constraints, examples –Physical data model (database schema) Other views of system?

What is a good model? Simplicity – generally, the simpler, the easier to understand and implement, and the more flexible Flexibility – how easily can the data model adapt to changing requirements? Integration – how consistent is the data with the rest of the organization’s data? – Better integration means more reuse, modifications are simpler, model provides easier understanding of business applications. Understandability Implementability

Database standards Naming data items Naming database objects Locations for objects Sample standards

ER modeling exercise Develop ER diagram

Evaluation Existing systems Meeting with users Merging views

View Integration Exercise Gather perspectives from users (assume none are complete) Lots of decisions when integrating –Integration strategy – one after another or all at once? –Resolving conflicts Dependency Key behavioral –Conformation of schemas – often requires more info than originally gathered