JCR for Roller

posted 01:28PM Nov 22, 2007 with tags jackrabbit jcr jspwiki microsling opensource roller sling weblog wiki by Lars Trieloff

Dave Johnson's wrap-up of the ApacheCon contains some interesting pieces: Of course he mentions the Shindig proposal, which I hold as one of the most interesting developments in the social networking space and he has written a longer paragraph on combining Roller (the weblog software) and Jackrabbit (the JCR repository that is the core of Day's CRX).
The idea of using a content management system to store Roller content keeps on coming up. At ApacheCon EU earlier this year, I spent some time talking to Lars Trieloff (who now works for CMS vendor Day Software) about implementing the Roller back-end interfaces using the Java Content Repository (JCR) APIs instead of the Java Persistence API (JPA) that we use now.
My rationale then was, to allow true free form collaboration in Mindquarry, we needed a weblog system. Mindquarry is based on Jackrabbit and I did not want to open another repository backend then, so I thought about creating a JCR-based backend for Roller that would easily integrate with Mindquarry.
At this ApacheCon, Noel Bergman brought up the topic a couple of times and pointed out that Day Software, has blog and wiki modules that are both backed by JCR. We could do the same thing: create version of Apache Roller and Apache JSPWiki (incubating) that share the same content repository.
The main advantage is that Roller and JSPWiki are content-centric applications. Every well-designed content-centric application moves sooner or later into the direction of having a separate repository layer. In JSPWiki the repository-layer allows you to have different backends, from flat files, to RCS to Apache Roller. In Roller there is a domain-specific repository implementation that is called "model", but if you have read my recent posts on microsling, you will note that using Model-View-Controller (MVC) for content-centric applications is disgusing the content-centric nature of the application, which would need a Content-Behavior-Appearance (CBA) model.
Later, Jukka Zitting (who also works for Day Software), suggested the idea of implementing JPA itself with JCR, thus allowing Roller to store its content in a CMS in a totally transparent fashion. This topic is interesting to me, but I don't fully understand the benefits of backing blogs and wikis with JCR. What new use cases would this support? How do the interesting features of JCR, like versioning for example, bubble up through Roller -- especially if Roller is to support both RDBMS and CMS back-ends?
I had a chat with Jukka yesterday in which he pointed out that implementing JPA based on JCR could be a very-cost effective solution and it might be the ideal way to go to migrate applications stuck with relational or object-relational backends to a content-based backend. Of couse, you would lose many of the advanced features that JCR offers you like full-text-search, observations, versioning because you have to mainatain backwards-compatibility to relational databases.

As always, this is a questions of frameworks and the right time to start a project. When the Roller project was started, there was no JCR, no Sling and no practical and standardized way of implementing content-centric-applications. With this in mind, it is easy to map some of the features JCR is offering to the needs of a blog application:

versioning
keeping all versions of a blog post, allowing incremental writing and backup
observations
notifications for new comments
workspaces
having a draft and a publish area for posts
hierarchy
posts belong to weblogs, comments to posts, etc.
export
backup
queries
tagging, categories, full-text-search

Disclaimer: I am Day's product manager for collaboration products, namely Blog and Wiki and I am a long-time user of Roller and JSPWiki. This blog post was written on Roller, using the JSPWiki plugin.

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Apache JSPWiki

posted 09:29PM Aug 11, 2007 with tags apache asf jspwiki opensource by Lars Trieloff

Via Dave Johnson I learn that there is a proposal to move JSPWiki to the Apache Incubator, which I regard as a great idea as the Apache Community and the JSPWiki community could benefit from each other and JSPWiki one of the two Wiki systems I use daily.