Originally published at O’Reilly
Recently, O’Reilly published a set of articles (Netscape Navigator 6.0 to Fail Standards Compliance, An Update, and Netscape 6.0 Released), written by the popular author David Flanagan, about the release of Netscape 6.0, Netscape’s newest entry in the browser marketplace.
David presented several valid concerns about bugs still present in the release of Netscape 6.0. And it is true, Netscape 6.0 did release with several unfixed bugs, many of which will have an impact on support for W3C specifications.
Our reaction to the release, however, was somewhat different. Along with other application developers, we’ve been waiting for the public release of an application that uses Mozilla’s XPToolkit, a set of software components from which Netscape 6.0 and the upcoming Mozilla 1.0 were built. Now that Netscape 6.0, which uses this framework, has been publicly released, we’re delighted: testing of XPToolkit may begin in earnest.
While many are focused on the release of Netscape 6.0, some of us aren’t. We’re more interested in the application environment created by the Mozilla team to support the implementation of browsers in general. To us, this framework is more important than the release of a new browser will ever be.
The reason for this is the changing face of the Internet, itself.
The Changing Face of Internet Applications
Current Internet applications rely on a centrally located Web server to distribute HTML over HTTP to clients. Each client, or Web browser, renders the source and displays a human-readable page.
This architecture has become so popular that you can’t pick up a magazine or a newspaper without hearing about Web servers or the new business models based on them. Although this architecture is based around universally located resources, most application-level resources are centralized and many other resources are hard to find. Some Web sites help you find other Web sites or “resources.” Others go so far as to offer completely centralized applications, as Application Services Providers (ASPs).
New technologies will soon force us to rethink the way we use the Internet. Distributed systems, mobile agents, and peer-to-peer (P2P) applications may completely undermine the need for browser-based Internet access.
P2P applications are already stepping around the browser. The next step will be around the Web server.
Consider this: a P2P application that locates and downloads a new function. The simplest example here may be provided by a P2P execution framework that uses XML-based remote procedure calls between peers to marshal XML-encoded functions. Instead of hitting Web pages, each peer locates and accesses both data and functions among a network of peers. No Web servers.
This scenario is not going to be best served by the traditional browser. Why?
The Limitations of Browsers
The things that made the Web browser a success in the beginning are the things that make it ineffective for new application models.
The browser was built to render files stored on Internet sites so we didn’t have to muck about with FTP. As soon as content became more visible, people started publishing yet more content, so browsers rendered HTML, then XML, formatted with CSS or XSLT. However, the browser itself has a very limited interface, even with new advances in W3C specifications. Sophisticated browser pages mean using either complicated object models–leading to cross-platform and cross-browser idiosyncrasies that are usually the result of standards initiatives–or using page-embedded applications, such as Java applets and plug-ins.
Even when the browser follows standard specifications, working within a browser page to create a sophisticated interface isn’t a simple or uncomplicated task.
In addition to the browser becoming increasingly complex as the nature of content becomes so, use of it implies that applications ought to be served from one location, and in one manner. To do something such as make a remote procedure call, you would need to use a digitally signed Java applet or some other browser-specific and limited technique. This is something that won’t bother newer P2P applications.
Finally, browsers were designed to be safe, and operate in a protective sandbox. Web-based applications served via a browser have difficulty getting at the user’s machine. Though safe, this restriction also prevents behaviors that would have the application modify its user interface. And this dynamism is going to be necessary in an environment where new services require new application interfaces that can be downloaded as data.
An Internet Application Framework?
Mozilla made a tough decision a few years ago–to scrap the Netscape 4.x architecture in favor of one built from the ground up. In the process, this open source team created an application environment based on reusable and interchangeable components.
With this application environment in place, the team then proceeded to build a sophisticated browser. They threw in Internet Chat, a Web page composer, and other complex things, all of which were released recently as Netscape 6.0. Often forgotten is that a powerful application environment came with it. This environment is now usable by developers of other Internet applications.
What types of applications? Well, ActiveState, the company that provides popular implementations of Perl and Python for various operating systems, used Mozilla to create itsKomodo product, a visual IDE for working with Python and Perl code. The user interface provides, among other things, colored syntax, syntax checking, and source-level debugging.
So, we have a browser and an application that can be used to create and test Perl and Python applications, all built from the same application architecture.
This is exciting stuff! Much has been written about reusable code and component-based design, and now we have an open source application environment we can all use to build our own applications.
Even more exciting is the extensible user-interface language from Mozilla called XUL (pronounced “zool”). It’s based on XML, which means you can use XML to create a user interface. Combine this with the ability to make remote procedure calls, and you have a perfect place from which to commence building a bunch of P2P applications, based on the scenario mentioned above.
Now, instead of opening a browser, you can open an application built on the same framework as your browser, but with a sophisticated interface of dropdown menus and tabbed pages–all created using XML. You can access remote procedure calls at the touch of a button and when you’re ready to access a new service, click another button, and in a couple of minutes restart your application. New entries will be added to new or existing menus providing access to the new service. All this is accomplished without Java bytecode, a new plug-in, or a DLL.
You’ve just downloaded XML.
When you explore the possibilities of the XPToolkit from Mozilla maybe you’ll agree that Netscape 6.0 is more than just a standards-based, better-than-Navigator-4.x-browser. It’s the start of a new new way of doing things on the Internet.