Viewlets, Portlets and Other Components

Types of component.

Viewlet

This is a new feature in Plone 3 and is used to provide aspects of the page furniture - those elements of the page which generally don't change throughout the site. These are organized by another type of component - a Viewlet Manager.

For more information you can look at

Portlet

Portlets in Plone are boxes of information, usually in the right or left column of a page, containing aggregated content or additional information, which may or may not be directly relevant to the content item being displayed. Behind the scenes these used to be constructed from ordinary page templates, but now, in Plone 3, they are wired together as components and are managed by another component - a Portlet Manager.

For more information take a look at:

View (Browser View)

We gave one definition of the term "view" above in the skin section. However, behind the scenes, in the context of components, View has a more technical meaning. It refers to a component which is usually made up of a Python class or a template or both and, put simply, processes the data from a content item before it reaches the page. There's a technical explanation in the Plone Developer Manual.

You'll sometimes see it referred to as BrowserView or <browser:page> and in templates you'll see a browser view's name prefaced by @@. We look at browser views again in the section on putting a page together.

Note that the term browser and the browser namespace are used to demarcate presentational components – that is, those bits of code which go to make up elements which will find their way to a web browser at some point.

Resource (Browser Resource) & ResourceDirectory

Although we've indicated that the skin and layers are the usual home of page templates, images and style sheets, it is also possible to turn them into components by registering them in ZCML. In this case you'll see them referred to like this ++resource++[resource name]. The same can be done for a directory containing templates and style sheets.

“Oh great”, I can hear you saying, “so which should I use, components or skins?” Go to the section Skin or Components? for a discussion of the pros and cons. At the time of writing we suggest the simpler option is to keep your templates, images and style sheets in your skin. We're just mentioning browser resources so that you know what they are if you encounter them.