Table module and table data gateway patterns

Question

I'm learning about patterns of j2ee, can anybody tell me what the differences are between table module(domain logic pattern) and table data gateway (data-source pattern)? Thank you

Answer 1

Table Module and Table Data Gateway are both table level patterns, but with a very fundamental difference.

A Table Module is a Domain Logic Pattern in the sense it can contain the BUSINESS LOGIC related to a particular table. A Table Data Gateway is supposed handle Database interface only and is not supposed to contain any Business Logic. Read "database interface" here as "insert/update/delete/read rows from a table".

Please note Martin Fowler's definitions which clearly specify this distinction.

Table Module : A single instance that handles the business logic for all rows in a database table or view.

Table Data Gateway : An object that acts as a Gateway to a database table. One instance handles all the rows in the table. ( "handles" here typically refers to CRUD).