OpenERP Architecture

OpenERP is a multitenant, three-tier architecture. The application tier itself is written as a core, multiple additional modules can be installed to create a particular configuration of OpenERP.
  
Client-Server Architecture:
        Open ERP has isolate client server components.The server runs 
separately from the client.It handles the business logic and communi-
cates with the database application.The client presents information to 
users and allow them to inter-operate with the server.Multiple client 
application is available.

Server and Modules:
        Server part is written in Python progrmming language.The client communicates with server using XML-RPC interface.Business functionality is organized into modules.A module is a folder with a pre-defined structure containing Python code and XML files.A module defines data  structure, forms, reports, menus, procedure,workflows,etc...Modules are defined using a client-independent syntax.So,adding new objects,such as menus or forms,makes it available to any client.

Client Applications:

   There are two client application are:      
       A web Application:               
           which is deployed as an HTTP Server to allow users to connect using web browser.
       Desktop Application:          
           Written in Python which uses GTK tool kit(Graphics tool Kit)

DataBase:

    OpenERP uses PostgreSQL as database management system.Postgres is an object-relational database management system(ORDBMS)

Reporting:
         OpenERP also provides a reporting system with OpenOffice.org integration allowing customization of reports.
          OpenOffice.org whose main components are word processing, spreadsheets,presentation,graphics,and database.