One of the most common problems I see with people developing Publishing sites stems from the lack of understanding in the core differences between Web Parts & Field Controls and when to use them. Many a consultant have dug a deep hole in this area. My goal in this post is to make you aware of the differences to make educated decisions when selecting one over the other.
What follows is a discussion with respect to MOSS 2007 Publishing sites (aka: WCM sites), but all the concepts apply to any Windows SharePoint Services 3.0 based site.
When creating editable content regions on a page layout, enabling content owners to add and manage their own content, developers/designers are presented with two options: field controls or Web Parts. These two options are very different and Publishing site developers should be aware of the differences. The fundamental difference comes down to where the data is stored.
Web Parts come straight from ASP.NET and their data is stored in a personalization store. Microsoft was nice and baked the personalization store into the site collection's content database. Data in a Web Part is stored within the context of the PAGE (ie: URL) & the user (which could be the shared user or a specific person). This does allow the content in Web Parts to be uniquely personalized by authenticated users.
In addition, developers and designers can only create Web Part Zones on the page layout. Content owners can then put any Web Part in the zones and any content within them.
Field Controls are much different from Web Parts. They are more like windows into list items. A field control pulls data (in display mode) from a particular column in a list item and writes back to that column in edit mode. Pages in a Publishing site are stored as items in a list; the Pages list. Because they are in a list, they can leverage all the benefits a list has to provide, but visioning & history is the most important here. Just keep one thing in mind: field controls are simply gateways, or windows, to the data.
When a developer places a field control on a page layout, they have the ultimate control of where it is placed on the page and any rules such as if the content owners can insert tables or images into the content. The content owners can only work within the rules defined by the developers.
What is the significance?
Great question! From my experience, MOST customers (90%+) who are rolling out a Publishing site, or Web-based content management systems such as MOSS 2007 WCM, are doing so because the following aspects are important to the project:
- Consistent look and feel (aka: a corporate brand)
- Empower content owners & subject matter experts (SME) to maintain the content
- Free up IT staff from updating content submitted by SMEs
- Structured organization of content and a versioned and/or historical record of the content
The challenge here is that Web Parts pose a problem with this approach. Because their data is stored in the ASP.NET personalization store in the context of the page (it's URL mind you) & the user. However with field controls, the data is saved with the page's list item. This means that when the page is updated, a new version is created and the old data is retained with the page.
Another challenge is with URLs in the content... especially relative URLs. Take the Publishing HTML field type & the Content Editor Web Part (CEWP). The CEWP does not store relative URLs... it stores only absolute URLs. Even if you enter a relative URL into the editor, it will be converted to an absolute URL. The rich text editor the Publishing HTML field type is tied to does not convert relative URLs to absolute ones.
If structure and history is important on your site, you should ONLY consider field controls for your content. If you want to have a more relaxed authoring environment where structure & history isn't important, Web Parts are better. What if structure & history is important... does it ever make sense to use Web Parts? Sure! Use them for providing functionality like stock quotes, consuming news feeds, or rolling up content (as in the Content Query Web Part). In this scenario, the only data that's stored is configuration data... not true content.
To summarize: the content in Web Parts is not versioned and there is no history, but the content in field controls is versioned & a history is retained (provided the Pages library has visioning enabled, which it does by default).
[Updated 10/9/2008 3:30p] A paper I've been working on that touches on this subject was published today on MSDN: Prescriptive Guidance for SharePoint Server 2007 Web Content Management Sites.