We've discussed problems with Roller's rendering system before. Folks have complained that the view technology is not pluggable, preventing the use of FreeMarker or JSP or other template languages. Another common complaint is that we place a confusing and difficult to document array values and objects into the rendering context. And we all seem to agree that we went overboard by defining too many small and/or unncessary macros. On top of that and perhaps as a result of that, the themes we've built on top of the current sytem are inconsistent and, with a couple exceptions, of generally poor quality.
So now, with Roller 3.0, the URL restructing work is going to address the pluggable view issue. At the same time the new Atlas frontpage work is going to introduce some new page models and a system for configuring them. We're introducing a lot of changes in the rendering sytem and the issues are clear in our minds, so now might be the very best time to address the rest of our problems with page rendering. I'd like to start fresh and introduce a new rendering system in Roller 3.0. I'm working on a proposal to create: 1) a set of new page models to replace the old PageModel and PageHelper, 2) a new set of macros, a redesigned subset of what have now and 3) ports of 2-3 Roller themes to this new system. As Allen suggested, I'm going to propose that we keep the old rendering sytem around, but make it optional. Moving forward new Roller installs will use the new system and new theme development will use it too. So, before I start churning up recent changes it the wiki, I'd like to get some feedback on my ideas so far. So please let me know what you think of the below. New page models We're using the notion of a "page model" in both the JSP authoring UI and in the rendering system, but I'm not sure if everybody agrees on what a page model is. So let's define it. A Page Podel is an read-only object that is placed into a Template View context, such as a Servlet request or a Velocity context, to provide data for display in template output. * Page models serve several purposes: - Clearly define data and data types available to template - Keep context's namespace free of clutter * Page models follow these rules - Page models are read only - Page models don't do HTML or other page generation What page models do we need? Different pages in Roller need access to different types of data. Let's review the different types of pages generated by Roller's rendering system. * All pages: need base URLs for site and access to some configs * Weblog pages: pages within a weblog need access to one weblog's data (Some also need access to site wide and planet wide data) * Weblog entry pages: Same as Weblog pages, plus one specific entry * Site wide pages: need access to Roller data across all weblogs (site wide feeds, for example) * Planet pages: need access to planet aggregations and groups (planet feeds, for example) With that in mind, consider these new proposed page models: * ConfigPageModel: provides access to selected config data - Available as $config to all pages - Access to runtime properties not declared "sensitive" in config def - Access to absolute URL of Roller and site - Roller version number and timestamp * WeblogPageModel: provides access to one weblog's data - Available as $pageModel in weblog pages * WeblogEntryPageModel: extends WeblogPageModel for single entry page - Available as $pageModel in single entry weblog pages * SitePageModel: provides access to site-wide weblog data - Available as $site to site-wide pages and to selected Weblog pages * PlanetPageModel: provides access to planet groups and subscriptions - Available as $planet to planet pages and selected Weblog pages * User defined page models - Can be defined for site-wide and specific weblog levels Other objects needed in context There are still a couple of objects that we need in context that are not page models. Here's the current list: * PageUtilities: small number of utilities needed by pages - Available as $utilities to all pages - Subset of those available in Roller 2.X utilities class * Text toolbox: allows access to I18N strings defined by Roller - Available as $text to all pages * Calendar: displays weblog calendar - Available as $calendarTag to weblog pages * EditorMenu: displays authoring menu (defined by editor-menu.xml) - Available as $authoringTag to weblog pages That's all I have so far. - Dave
