Zope: Web Service Overview

The Engineering Computer Network provides a robust, secure, and scalable web hosting platform which simplifies maintenance of complex web sites. This service is commonly referred to as the Engineering Web Cluster or the ECN Web Cluster.

The Web Cluster is powered by Zope (http://www.zope.org), an open source web application server. Zope provides the following:

• Objects - Content created within Zope exist as one of many types of objects. Folders, Files, HTML Documents, Events, Templates, Scripts, and Database Connections are examples of Zope objects. Objects are stored in a database called the Zope Object Database (ZODB).
• Through the Web (TTW) Editing - Each object has its own set of management screens (web pages) for editing. Management screens are accessible from any web enabled computer. This means that web content can be created or modified regardless of your location.
• WebDAV - WebDAV (http://www.webdav.org/), short for "Web-based Distributed Authoring and Versioning", is a protocol, similar to FTP, for transferring objects to and from Zope. WebDAV provides an alternative to uploading or creating content through the web.
• Security - Fine-grained security settings provide developers with an easy way to delegate content maintenance to any number of users. Tools for integrating with the Purdue Directory and I2A2 services have already been developed.

• Python - All scripting within Zope is done using Python. This provides a standard, easy to use, object oriented language for developing applications.
• Relational Databases - Connectors to a number of relational databases including Oracle, PostgreSQL, and MySQL are available. SQL Methods are then created and linked with a connection to provide a data access layer. This sets up a clean and easy way to access all of your relational data.
• Scalability - Zope Enterprise Objects (ZEO) provides scalability in the software layer to ensure that Zope can scale to our demands.

The Zope software runs on a Linux cluster comprised of three layers: Apache, ZEO Clients, and Storage.

• Apache - Redundant Apache web servers sit at the front of the cluster. The Apache servers provide SSL encryption of all traffic, access logging, and load balancing.
• ZEO Clients - ZEO Clients receive requests from the Apache servers, these requests are processed and returned. The processing required to construct a page or run a web applications takes place in this layer.
• Storage - The ZEO DB server contains the master copy of all Zope objects. When a ZEO Client needs an object to fulfill a request that object is loaded from the storage layer.