Using Web Storage System Forms

In "Customizing OWA 2000," March 2001, InstantDoc ID 19714, I introduced Microsoft Web Storage System (WSS) Forms as a mechanism for changing the default Outlook Web Access (OWA) processing. Now let's look at the various WSS Forms technologies that you can use to override default processing and how to use one of those technologies.

The WSS Technologies
The WSS is an ideal platform for developing Web-based collaborative applications because the WSS has a URL-addressable store and supports several data-access methods, including ActiveX Data Objects (ADO) and HTTP-DAV (aka WWW Distributed Authoring and Versioning—WebDAV). Four key technologies generally fall under the WSS Forms name. These technologies can help you develop collaborative applications:

• Forms registry. The forms registry enables applications to render items (e.g., folders, mail messages, calendar items) that an HTTP request references, thus overriding the default OWA rendering. In other words, the forms registry permits the use of application-specific HTML and Active Server Pages (ASP) forms in response to a URL.
• Forms renderer. The forms renderer enables application-specific HTML and ASP forms to include data that's contained in items in the WSS. The renderer works in conjunction with the forms registry. You can use the forms renderer to create and update items in the WSS.
• Folder-view control (aka View behavior—wfview.htc). Folder-view control is a dynamic HTML behavior that you can include in HTML forms to display items contained within a folder in a table. This powerful control lets you perform many tasks, including specifying which properties you want to display and manipulating items (e.g., filtering, grouping, sorting).
• Microsoft FrontPage extensions. With add-on FrontPage extensions, you can easily author HTML and ASP forms that use the WSS. Behind the scenes, these tools extensively use the forms registry, the forms renderer, and folder-view control.
• The forms registry has been available since the first release of the WSS in Exchange 2000 Server. The other technologies have been available in various beta forms but now ship with Exchange 2000 Service Pack 1 (SP1) and Microsoft SharePoint Portal Server (formerly code-named Tahoe).
• Admittedly, the four technologies are aimed at developers. However, as an Exchange administrator, you need to understand the technologies' capabilities so that you can provide support to your developers. In addition, you can use the technologies to make some administrative tasks easier. For example, you can use the forms registry to temporarily prohibit a user from creating new items through OWA or to force a user to delete items in a particular folder when the number of items exceeds the specified threshold. You can use the folder-view control inside a custom Web page to show custom views of the same public folder on multiple servers to troubleshoot replication problems.
• Although you can develop applications for the WSS platform without using any of these technologies, you would be missing out on some powerful techniques that can make your applications far more adaptable and manageable. Let's take a detailed look at the forms registry and how to use it. (You can find information about the other technologies on the Microsoft Developer Network—MSDN—at http://msdn.microsoft.com.)

The Forms Registry
Every item and folder in the WSS is URL addressable. This addressability, in conjunction with the forms registry, lets you take a datacentric approach to your applications and build UIs that adapt to the operating environment. Consider an application that needs to display data in the user's chosen language. A formcentric approach to building this multilingual application involves invoking an ASP-based form that passes query strings to the URL. The query strings identify the language to use and the key needed to retrieve the data (e.g., http://ardbeg/myapp/myform.asp?language=english &user=laahs&folder=Inbox&subject =welcome.eml). With a datacentric approach, the multilingual application needs only to reference the data as a URL and the WSS automatically uses the relevant form to render the data. For example, if you associate myform .asp with the URL http://ardbeg/exchange/laahs/inbox/welcome.eml in the forms registry, whenever a user specifies that URL, the WSS automatically uses the English-version form to render the data. (I explain shortly how this feat is possible.) . . .