When push comes to app dev - use of push technology in new applications - IT Trends - Internet/Web/Online Service Information - Column

Software Magazine, Dec, 1997 by Dan Kare

By now, you've all heard of push technology--the current darling of the press, analyst, vendor, and venture capitalist communities. Push technology offers the ability to "push" HTML pages and other data and software onto the browsers of user desktops without the user specifically requesting the material. "Specifically" is the key word here. You see, in reality, push technology is only an automated version of the "pull" techniques that are the bread and butter of the browser/Web server interaction model.

While the first generation of push technology and products focused on file automatic delivery of HTML pages, expect to see the approach employed in software development. Specifically, automated push offerings can be used to distribute software updates and build Web-based workflow applications. In addition, push solutions might be required to guarantee application consistency in Internet applications based solely on HTML.

The glory of the Web--its simplicity -- is reflected in the limited number of Web protocols and the uncomplicated interaction model for Web-client-to-Web-server communication. For example, Web browsers all support some form of HTML, while the underlying communication software uses TCP/IP-based sockets to accept requests and return responses using HTTP. To begin a Web interaction, a browser connects to the HTTP server and requests an HTML page. Then the Web server responds to the request by returning an HTML page, or by triggering an external application via a server API or other mechanism. Once the page is delivered to the browser, or the application executes, the transaction is complete and the connection closes. Under this scenario, the browser requests or "pulls" information from the Web server.

Designed to automatically deliver HTML pages and other information in a customized format at specific times, push technology automates the task of requesting information from the Web server. It is the degree of automation and intrusiveness that differentiates the various classes of push technology solutions.

The least automated type of push solution, as well as the least intrusive, is rooted in a simple notification model that is based on E-mail. This form of push solution, which is typically manifested as an E-mail-based news service, is prevalent and has been in use since the 1980s. Users subscribe to an information service that automatically sends highly targeted information to their E-mailboxes at regular intervals. The business model for this type of push solution has vendors paying for advertisement that is attached to the E-mail information. Examples of notification-based E-mail-delivered news services include MIT's Fishwrap, InformationWeek's 1W Daily, and the San Jose Mercury News' NewsHound.

E-mail-based push solutions have traditionally been delivered as text. But in 1996, a variety of multimedia E-mail and Web-mail push services, such as Netscape's In-Box Direct, began to appear. Some of these services deliver multimedia HTML pages to Web browser mail clients such as Netscape Navigator.

Profile-based Push Solutions

While push solutions based on E-mail and a simple notification model might not be intrusive or resource-intensive, they're lacking in interactivity and specialization. In contrast, a new generation of push solutions provides highly customized information in a visually appealing, dynamic environment. The interactive environment is often provided by a Web browser, while the customized content comes when users set up their preference profiles wherein they describe the types of information that interest them.

Profile information can be located either on the user desktop or on a remote server. In the latter case, it is the server's responsibility to monitor the Web for matching conditions and then send the appropriate information in the form of E-mail notifying the users when those conditions are met. Conversely, the server might download requested HTML pages from the server to be stored locally on the client for future perusal. Since it is the user's responsibility to act on the messages or HTML pages sent by the server, this form of push solution is often referred to as "automated pull." Automated pull products include BroadVision's One-to-One, Cognisoft's Intelliserv, ForeFront Group's Web-Whacker, and Diffusion's IntraExpress.

A third type of push solution is generally designated "automated push." Typically, the profile information is stored on the client desktop, and client-based polling software periodically requests information from the server based on information in the profile file. If a matching condition is found, the appropriate information is transmitted from the server to the client. With some solutions, the profile information takes the form of a subscription to content channels -- such as stocks or sports -- that, is constantly broadcast from the server to the client. Automated push solution vendors include PointCast, Marimba, Wayfarer, BackWeb Technologies, and Intermind.

Enter Software Development