[{TableOfContents }]

!!! Introduction
It's common for people to use a wiki and some discipline to replace a more complex application. They can add some plugins to make it easier.

It would be awesome to be able to program extensions of a wiki inside the wiki:
* integrated revision control
* low barrier to entry
* programming on the web

!!! Related notions
!! Existing plugin mechanisms
! Confluence plugins
The Confluence wiki allows for a lot of [different plugin types|http://confluence.atlassian.com/display/CONFDEV/Confluence+Plugin+Module+Types]
! JSPWiki plugins

!! Scott's wikitools
Scott just started some work on wiki extensions that allow to access the wiki from outside and that make use of templates [Wiki Tools]

!! Databases

Most applications need to store data and often use a database. It's common to store large amounts of data on a wiki with a repetitive text format. This is in effect a primitive type of database that tends to mix data and its presentation.
Plugins can be used to allow access to a database from a wiki page ([Database and Wiki])

!!! Use cases/Applications
!! Elementary use cases
! Text to graphics
It would be nice to be able to input some parameters and information and obtain a graphical representation. This can be achieved for certain graphical representations with Java JSPWiki plugins (e.g. [ImageGen Plugins]). With a template engine, [SVG|Wiki and SVG] and some Javascript, we could probably create new similar plugins from the wiki.
! Data sheets
It would be nice to be able to create a simple database application simply by following some conventions (e.g. type JSON code or maybe wiki lists with key,value pairs) and then be able to perform some operations on it:
* render a template with values taken from a data sheet page
* search for pages with a certain key having certain values
The Weblog plugin of JSPWiki is an example of this type of application 

! CGI wiki pages
CGI scripts (and other dynamic webpages) can set their output mime type and generate content on the fly. The wiki engine could have a new .jsp page that runs the regular page through the wiki engine without all the skin information and lets the page set its mime type.
This would allow users to compose multiple such wiki pages simply by referencing the URL. This is very much like attachments and it might actually be seen as a special case, so the wiki tag for attachment could be reused.
!! Complete application
! Catalog app
Many applications are just specialized catalog apps. The common example is a CD,DVD, book catalog. But a bug database, a collection of crash stacks (http://www.kerneloops.org) are really essentially the same thing.

A wiki is a natural fit for catalogs and can mostly be used for that without any additional development of plugins:
* use templates to assist with data input
* use regular search to find elements in catalog
* use tagging if available to get more restricted searches (ex: issues tagged as open)

A more full featured and custom developed catalog app would often feature:
* data validation
* forms instead of simple
* automatic completion to help with data input
* advanced search matching specific data fields
* reports, graphs and charts regarding the data

! Requirement tracking

Requirement tracking can be reduced to tagging software or system documentation and producing reports from those tags to check that the requirements are taken into account in the design, the code and tested. This is typically a document-centric activity and many systems are actually based on Microsoft Word or have to interface with it.

This is therefore a natural fit for a wiki:
* documentation can be done inside wiki pages
* requirement marking (definitions, references) can be done with simple text markup
* search mechanisms in a wiki can locate the text markup of requirements
* multiple pages can be merged into one and each requirement, test or other tracked item could thus have its own page to be easily referenced.

Additional features could include:
* cross referencing of requirements and other tracked items
* more freedom in the way the documents can be organized and edited

! Language learning app

[Language learning app]

!!! Template plugin

Scott is into [Velocity templates|wiki Tools] these days and plugins for JSPWiki tend to print a lot of text with some variable parts, so this looks like a good way to design plugins. If most of the interesting parts of a plugin end up in a template, this brings the question of allowing a more generic plugin that takes the template from a wiki page and builds a velocity context to run it.

A velocity context can provide:
* formatted data an objects (e.g. key/value pairs defined in a plugin invocation or in a document referenced by the invocation (raw page, rendered page, attachment)
* access to methods and objects