Network Computingwww.networkcomputing.com

We were quite taken with BackWeb, a flexible, powerful, Web-developer-friendly, dedicated-server push product that has tremendous potential for a variety of Internet/intranet applications. Castanet's software push architecture also demonstrates great potential, provided someone on your development team has solid Java programming expertise.

The Browser Does It All
Internet Explorer 4.0 and Netscape Communicator 4.0 feature a number of auxiliary functions, including Web page authoring, group calendaring, Internet Mail Access Protocol (IMAP) e-mail access, conferencing and push technology. If your users' needs are fairly straightforward, they can configure their own push content via basic browser Web crawl capabilities. Or you can preconfigure some Web crawls using browser administration tools. (Mission Control for Netcaster and the IE 4.0 Administration Kit were not available during testing.)

If you want to develop dedicated Web channels that specify push channel content and update schedules, you'll need to decide between IE 4.0 and its Channel Definition Format (CDF) or Netcaster, which uses JavaScript 1.2. That decision likely will be based on your expertise with Web development technologies and your installed browser base, since IE 4.0 and Netcaster provide comparable channel functionality.

We found the new browser-based push interface less frie ndly than a dedicated proprietary push interface like PointCast, and it's doubtful that these tools will suffice. The browser is clearly set to become the primary push interface. The PointCasts of the world will find a niche within the browser framework (by aggregating content or providing intelligent news delivery, for example) or offering a very compelling user interface alternative. Or they'll be out of business. Most push vendors and premium channel providers have aligned with Microsoft or Netscape, or both.

Microsoft Corp. Internet Explorer 4.0
Microsoft offers excellent basic automated Web crawling, which constitutes Internet Explorer 4.0's basic push mechanism. It has a more advanced channel push based on CDF, an application of Extended Markup Language (XML) that is now a proposed standard within the World Wide Web (W3) Consortium. CDF looks fairly easy for Web developers to use, since it's somewhat HTML-like and offers great flexibility in configuring an existing site for channel delivery.

We installed and tested IE 4.0's Platform Preview Release 1 on two Pentium boxes running Windows95. According to Microsoft, the final release of IE 4.0 should be out for Windows95 and NT 4.0 in September, with releases for Windows 3.1, NT 3.51 and Apple Macintosh coming within the following 90 days.

IE 4.0 offers a somewhat fragmented, multitiered push architecture. At its lowest level is the basic Web crawl. This is defined by adding a Web site to your Favorites menu and checking the Subscribe To check box, or selecting a Subscriptions from the Favorites menu. In either case, you specify the number of levels deep that you'd like to crawl, whether you want pages downloaded (you can be notified of changes only), content screening options and Web crawl scheduling. IE 4.0 feeds these preferences to a Web crawling agent. Based on the schedule you've specified, the Web crawler uses a standard HTTP query to determine whether pages have changed, notifies you if a site has changed through a task bar icon or a red gleam in the Favorites menu, and uses the specified depth and content screening parameters to download updated information.

We subscribed to a number of Web resources and these approaches worked well. For some sites we utilized the e-mail notification option and also requested that the top-most page be mailed to us. We assume that most users are fairly savvy when it comes to manipulating browser menus and filling out dialogs, and will easily grasp the subscription concept, so they'll have no problem utilizing this new tool.

With Active Desktop, a component of IE 4.0 that requires its optional Shell Integration, ActiveX controls let you anchor any IE 4.0-compatible Web page directly to the desktop. You can configure an Active Desktop component as a subscription, transforming the Windows desktop into a useful area for organizing access to continually updated Web information and applications.