Our story begins in 1996. Jim Fulton was technical director at Digital Creations. At the International Python Conference (IPC) that year, Jim gave a presentation on CGI: Python and Internet Programming. Jim, considering CGI less than elegant, envisioned a better way to program for the internet in Python. According to legend, Jim learned CGI on the plane to the conference, and designed Bobo on the plane ride back home.
Digital Creations then released three open-source Python software packages: Bobo, Document Template, and Bobopos. These packages – a web publisher, a text template, and an object database – were the core of Principia, a commercial application server. In November of 1998, investor Hadar Pedhazur convinced Digital Creations to open source Principia. These packages evolved into the core components of Zope 2 and Digital Creations became Zope Corporation.
Since those days Zope has been under active development. It has evolved in several ways as the community gained experience, continually seeking the optimum balance between power and ease of use. Zope 2 emphasized rapid development, the Zope Component Architecture, which is the core of Zope 3, emphasized modularity and configurability which proved very successful in “enterprise” applications requiring flexibility and scalability.
Zope 3 is now known as BlueBream. The name stems from the coincidence that the Z Object Publishing Environment when spelled zope is the name of a species of fish. Blue bream is another name for the same species.
BlueBream combines the ZCA, Buildout into a well defined, and documented, that makes building powerhouse applications fun.
The components which comprise BlueBream are under continual development by an international team of experienced coders.
The longer learning curve for deploying Zope 3 is overkill for some situations which would otherwise stand to benefit from the distilled wisdom of the ZCA. The Zope community has responded to this in with several rapidly deployable ZCA-derived frameworks, which implement Convention over configuration while maintaining the power of ZCA under the hood. Notable among these are Grok and Repoze. Take a look at the recent uploads to the PyPi site, it is rare to not see several zca projects listed.
The original intent of Zope 3 was to become a replacement for Zope 2, however this did not happen as planned. Instead Zope 2 continued to make up the majority of new Zope deployments, mostly due to the popularity of Plone.
Zope 3 was conceived as a fresh start to leave certain aspects and limitations of its presumed predecessor Zope 2 behind. Zope 3 introduced a new component architecture to address some of the inheritance-based-programming limitations of Zope 2.
The ZCA notionally includes the packages named zope.component, zope.interface and zope.configuration. Zope 3 added to this a large number of extra libraries and provided an application server that enabled programmers to develop standalone web applications.
In the meantime another wave of web frameworks appeared. Grok evolved with many Zope 3 libraries at its core. repoze.bfg (aka BFG) evolved around the ZCA. Additionally Zope 2 began to make use of the ZCA and various other Zope 3 packages.
In 2009 a group of Zope developers agreed to concentrate primarily on the development of the Zope 3 libraries and formed the Zope Toolkit (ZTK) that focused on a slim library subset of the Zope 3 project, which can then be efficiently utilized by web application frameworks on top. This development led to the following logical steps:
BlueBream can thus be seen as the successor of Zope 3 web application server that like Grok relies on the ZTK.