Odyssey 3 Application Structure

This page explains all the pieces required in order to implement an application that uses the Odyssey framework.

Project Directory

Each application has a project directory rooted at svn+ssh://odyssey@core.cs/u/odyssey/svn/odyssey/trunk/project/[application].

This directory is for any miscellaneous files related to development such a shell script for invoking the application and test scripts. Additionally, there is a relative symlink, to to the Python code and SQL schema for the application.

Python Code

The Python code for each application follows typical Python packaging conventions. Typical subdirectories may include:

• db — files containing database interface procedures
• core — files containing “business rules” or other non-UI-specific implementation
• webui — files containing web user interface implementation

The whole directory is maintained in Subversion at svn+ssh://odyssey@core.cs/u/odyssey/svn/odyssey/trunk/python/uw/local/[application]. This means that applications can access each others’ code by importing the appropriate Python module named uw.local.[application].….

SQL Schema Definitions

The SQL schema definition for an application is broken up into a number of files. There is always an init.sql file; executing this file as the appropriate Postgres user will create the schema corresponding to the application and assign appropriate role permissions, all within a transaction. Normally, there will be a one-to-one correspondence between applications and Postgres schemas. Regardless, the schema definitions are organized by Postgres schema.

The init.sql file in turn includes init_data.sql, init_view.sql, and init_perm.sql. These are responsible for creating all objects in the schema:

• init_data.sql — Creates all tables (and sequences). In particular, the objects created here are the ones which, if dropped and re-created, will have lost something (in particular, the data stored in the tables; current value of sequences). Typically this simply includes a number of files of the form [section]_data.sql.
• init_view.sql — Creates all non-data-holding schema objects, including views and functions. The important distinction here is that these objects can be dropped and re-created in a working database without losing anything. Typically this simply includes a number of files of the form [section]_view.sql.
• init_perm.sql — Assigns all role permissions. Does not create the roles themselves; that is done manually.

The SQL schema is maintained in Subversion at svn+ssh://odyssey@core.cs/u/odyssey/svn/odyssey/trunk/sql/[schema], where [schema] is the Postgres schema name.

-- IsaacMorland - 05 Nov 2008