Plone is a content management system that is built on the powerful Zope application server. The project experienced many delays with its 2.1 release. This made it difficult for Plone consultants to choose whether to use the old release or wait for the new one, and users faced many upgrade issues when 2.1 was finally released and had many changes. Partly to address these problems and partly in order to sync their releases with Zope, they decided in 2005 to move to a six month time based release cycle.
- Releases, in particular version 2.1, took a long time to get out.
- Releases had many changes and caused some migration problems.
- Many Plone developers work as consultants building web sites. Because of the unpredictability of Plone, it was difficult for them to decide which version to use for future projects.
- Plone moved to a time based release, partly because the Zope framework on which it builds has done so. This allows them to make use of new Zope features in their software.
- Time based releases allowed the project to implement more structure. For example, new features have to be proposed as a Plone Improvement Proposals (PLIP) which the framework team reviews.
- Deadlines have motivated developers to get their features done within a certain time frame.
- Plone consultants can decide in advance which version of Plone to use for future commercial projects.
- As the project has moved to time based releases only recently, they still need to show whether they can consistently release on time.