Python Web Frameworks Overview: Zope

URL

http://www.zope.org

Licence

ZPL - Zope is open source, as are many of the extensions and add-ons available for it.

Deployment Platforms

• As a standalone server - this is the default, which permits Zope to be run relatively easily "out of the box".
• Integrated with a Web server using CGI, PCGI or FastCGI.
• The Zope environment is provided by long-running processes.

Operating Systems

Zope works on UNIX and Windows platforms.

Suitability

The "out of the box" single server option makes Zope attractive for developers who either do not want to integrate many components or have little experience in doing so. The need to have Zope processes continuously running excludes Zope from certain hosting environments, but being available as a packaged product with explicit security features, Zope is also attractive to other, potentially more specialised hosting companies. Thus, Zope hosting can be had, even for free, with certain hosting providers.

Development Interfaces

• Presentation-oriented - DTML methods and templates provide a lightweight introduction to the processing of inputs and the production of Web pages in response.
• Object-oriented, servlet-like - external methods and Zope Products expose request and response objects to Python components.

Environment Access

• Zope's object database (ZODB) is the principal means of associating resources with application components.
• Adapters which provide access to external resources, such as database systems, are available for use with Zope.

Session, Identification and Authentication

• Zope 2.5 (and earlier releases with CoreSessionTracking) provides a mechanism for the identification of users.
• Zope has always supported authentication for "site editors", but such support may only be appropriate for "content management" applications.

Persistence Support

• Zope provides near-transparent object persistence in the object database, and it is possible to have multiple object database instances.
• Interaction with relational database systems is typically performed using SQL.
• Certain tools are available for querying object database instances, but the reliance on ZODB for the storage of application data (should this be chosen) may be a significant concern in certain environments.
• A noticeable tradeoff therefore exists between convenience of persistence (using ZODB) and openness of access (using SQL-based databases).

Presentation Support

• DTML - Zope's original presentation technology which provides additional special tags for use in HTML or other textual resources.
• ZPT (Zope Page Templates) - a presentation technology which specifies XML attributes for use with XML-based documents.

Other presentation systems could presumably be supported in Zope, but from Zope 2.5, the above technologies appear to be "first class".

Comments

Zope provides so much support for some activities that certain kinds of applications can be created and configured in very short periods of time, given enough experience of Zope development. Where object persistence is required, for example, Zope applications require little effort to make such mechanisms work, whereas other frameworks (such as Enterprise JavaBeans container-managed persistence) require a certain amount of administrative overhead (the declaration of each object schema) and may be prone to obscure failure, given the complexity of the integration and configuration of many different systems.

The means of configuring or customising applications in Zope seems very clever - by storing documents or objects at particular points in the object database, Zope's "acquisition" mechanism permits applications to find resources according to where both applications and resources reside, relative to one another. Moreover, by supporting such dynamic environmental lookup, Zope encourages the redistribution of applications by reducing the restrictions on how such applications need to be set up.