The rapid growth of the technologies behind the World Wide Web has seen it change from a tool for distributing hypertext documents to a powerful application framework, ready for the development of enterprise systems. Already businesses around the world are using web technologies to provide a common user desktop in an Intranet, or to “downstream” their business systems to customers and suppliers through an Extranet. It’s no longer sufficient for a business to have just a corporate web presence.

A successful web application can be very high profile public system, like the Federal Express parcel tracking system, or the Alliance and Leicester’s mortgage management system. It can also be a low profile tool that simplifies some aspect of a business’ transactions, from allowing customers to collect documentation as and when they need it, to building a quick and effective communication channel between a mobile sales force and head office. Once a business has decided to develop web applications, it needs to decide how to implement them - and there are plenty of ways to go about developing and rolling out

Traditionally web applications have been developed using the Common Gateway Interface, a standard series of environment variables, used by external programs or scripts to take input from a form embedded in a web page, with data passed through a web server. The external application then generates an appropriate web page in response to the inputs. This process could be slow, and was often inflexible.

The latest generations of web servers have taken this a stage further, by implementing published APIs that allow developers to add extra functionality to the server. All three of the most popular web servers allow this: Apache uses a range of different plug-in modules, Microsoft’s Internet Information Server has ISAPI, and Netscape’s Enterprise Server has NSAPI.

These interfaces have been extended still further, with a range of technologies that allow users to either script the behaviour of web pages directly thanks to a server object model, or, taking a fully object oriented approach to use Java and CORBA to turn the web into a distributed applications environment - or even to mix the two technologies.

The latest generation of web application development tools have taken advantage of these technologies, and have used integrated development environments and visual development tools to speed the development process.

Microsoft Visual InterDev and Internet Information Server 3.0

Microsoft’s Windows NT 4.0 web server, Internet Information Server, added a powerful server scripting environment in version 3.0 with Active Server Pages (ASP). This allows you to use a mixture of server side ActiveX or COM objects, together with a semi-object oriented scripting language, VBScript, based on Visual Basic, to produce dynamically generated web pages.

Whilst it is possible to produce ASP web pages by hand using a text editor, as they are constructed in standard HTML with VBScript inserted inside a modified version of the comment tag, Microsoft have included Visual InterDev in their Visual Studio suite of development tools. This uses a common IDE with Visual C++, Visual Basic and Visual J++, and allows you to develop ASP-based web applications quickly and easily.

VBScript commands can be added at point in a web page, and complex page structures and content-negotiated applications can be developed using a range of control structures. The main feature of the Visual InterDev/ASP combination is the use of Microsoft’s Advanced Data Objects. These are server side ActiveX controls that encapsulate the ODBC based Remote Data Objects, and allow direct connections from an ASP web page to an external database. Once a database connection has been made, a page contents can be created as a result of SQL queries. A visual query designer allows complex SQL queries to be built quickly, using a similar interface to Microsoft’s popular Access database.

The latest release of Internet Information Server, IIS 4.0, is included in the Windows NT 4.0 option pack, and adds a large number of objects to the server object model, including transactional objects based on the Microsoft Transaction Server and a range of file system objects.

Users aren’t limited to using VBScript, as an open scripting API has allowed third parties to produce scripting environments - including PERL, REXX and Python. In fact, you’re not even limited to working with Internet Information Server, as Chili! Software’s Chili!ASP product provides ASP scripting facilities for, amongst others, Netscape’s web server.

Allaire Cold Fusion and HomeSite

Allaire’s recent purchase of the HomeSite HTML editing tool has increased the reach of it’s Cold Fusion web applications environment. Cold Fusion is designed to add on to a wide range of web servers on Windows NT and Solaris, though the development environment, a derivative of HomeSite, Cold Fusion Studio, is designed for Windows 95 and NT.

Unlike most of it’s competitors HomeSite isn’t a WYSIWYG tool, and uses a tag based text editor to create HTML pages and to add Cold Fusion’s own CFML mark-up tags, as well as server side and client side scripts, allowing you to mix Cold Fusion and ASP in a single web application. A built in browser, which can be an encapsulated copy of IE 3.0, allows you to switch between page layout and a preview without leaving the editing environment. HomeSite also features the latest HTML technologies, including DHTML and Cascading Style Sheets.

Cold Fusion Studio extends HomeSite, and turns it into a team based applications development environment, using the bundled StarBase version control system. A local copy of Cold Fusion Application Server also means that complex applications can be developed on a desktop workstation rather than live on a server. Cold Fusion Studio allows you to build CFML applications using a visual tool which uses “point and click” to help build functions. You can also use Cold Fusion Studio to store commonly used pieces of code for reuse in other projects.

Like Visual InterDev, Cold Fusion Studio includes a visual query builder, so that you can build SQL queries against any ODBC compliant database. A simple drag and drop interface allows you to build complex SQL statements quickly, and also test queries before adding them to a web application.

The Cold Fusion Application Server is at the heart of any Cold Fusion application. A plug in module for most major web servers, the Application Server interprets CFML code and handles database and email connectivity, as well as integration with LDAP directory services.  Cold Fusion Application Server has a range of features designed to give high performance, ranging from multi-processor support to pooled database connections and p-code compilation of web pages. If you’re building a web application to work with heritage systems, an open API lets you build your own code to handle access to non-standard systems. The NT version also supports DCOM, so applications can be directly linked into Microsoft BackOffice based systems.

Netscape ONE and Visual JavaScript

Netscape’s Open Network Environment is a web applications environment based around the Netscape Communicator browser and the SuiteSpot family of web servers. Using JavaScript, Java, JavaBeans and CORBA, Netscape ONE is designed to use open Internet standards to develop “crossware” applications that can run over any IP network and across many different operating systems.

Netscape are committed to a component-based application development model, and reusable JavaScript scriptlets and JavaBeans components are at the heart of Netscape ONE applications. All of the SuiteSpot servers are designed to communicate with applications via JavaBeans - so that, for example, an application designed to send an email message via the Netscape Messaging Server only needs to set the properties of a messaging JavaBean.

Netscape initially developed their LiveWire scripting model on their web server products, and have extended the server object model with the release of Enterprise Server 3.0 to include direct access to major database products, including Oracle, as well as ODBC access to many other databases. Using server-side JavaScripts, applications can be developed that handle database transactions either through direct interfaces or via the bundled Visigenic CORBA compliant ORB. This also allows access via the IIOP protocol to client side Java applications and applets running in the Netscape Communicator web browser, which includes an ORB in the 4.0 release.

A key part of the Netscape ONE environment is Netscape’s Visual JavaScript development environment. Written in Java, this allows you to develop web applications, in a drag and drop environment, as well as letting you edit the resulting code directly. A component library allows access to a range of pre-built Java and JavaScript components, which include database access and report tools and input form controls.

Netscape’s commitment to the ONE model is shown by its plans to redevelop all of its client and server products as collections of JavaBeans. A JavaBean HTML rendering engine is due early in 1998, and will be followed by a new range of servers.

NetDynamics Enterprise Network Application Platform

NetDynamic’s Enterprise Network Application Platform extends the Internet and it’s associated technologies, using them as a framework for distributed applications development. The latest version, 4.0, is a full fledged Java, JavaBeans and CORBA development environment. The NetDynamics environment consists of five component parts: the Applications Server, Platform Adapter Components, the Command Center, a Java Object Framework, and the Studio.

The Applications Server is the heart of the NetDynamics suite. This is a Java application server, which links via server APIs and CGI to most web servers, and which uses IIOP to connect to Java applications running on client browsers. Data access components allow access to most relational databases, via SQL queries, and if run on Windows NT, you can use DCOM. The Application Server is designed for high-availability, and implements load-balancing between server components, producing scalable-applications.

Using Platform Adapter Components, which are built to use CORBA, NetDynamics Applications Server can be connected to a wide range of third party platforms. PACs are already available to provide interfaces to SAP and PeopleSoft, and are in use in several large US corporations. One of these, AT&T, use NetDynamics to extend PeopleSoft human resources applications to 65,000 employees.

One common problem with web application environments, is that it is very difficult to provide effective performance monitoring and control. NetDynamics include a Command Center, written in Java. This allows you to monitor the performance of your NetDynamics application in real-time, and allows you to move components from one machine to another, as well as viewing alerts and statistics.

The Java Object Framework is a series of over 400 ready built classes, with 4,000 methods, and uses the improved JDK 1.1 event model. Using these with the Studio IDE, you can build enterprise-ready Java applications. The Studio is a visual IDE, which includes support for team development, integrating with version control systems from a wide range of vendors. You can use the Studio as an automatic code generator for both Java and HTML, reducing development time. The Studio also includes a debugger that uses IIOP to interrogate application components on remote machines.

HAHT HAHTsite

One of the first web application development environments was HAHTsite. Composed of a powerful visual IDE , a Visual Basic for Applications-based scripting language HAHTtalk, and a multi-platform Application Server, HAHTsite is designed for the rapid development and roll out of server-based web applications, delivering a thin HTML client to users’desktops.

The HAHTsite Application Server is a standalone package, which links to web servers either via the common CGI, or through Netscape’s and Microsoft’s APIs. If you’re using Oracle’s Application Server (the new name for the Oracle Web Server) you can also use it as a cartridge for the web request broker. Running on NT, HP-UX, Solaris and AIX, HAHTsite’s server allows you to generate code and deploy it with out converting between operating systems. Large scale enterprise systems can be built using a distributed version of the Application Server to add scalability and high availability, together with load-balancing. You can also use the distributed Application Server to host applications behind a firewall. All versions of the Application Server can be managed using a secure web interface, which lets you monitor performance and change application parameters as and when required. Access to external systems can be through a wide range of different tools, including OLE, CORBA and TCP/IP sockets.

HAHT have licensed Microsoft’s Visual Basic for Applications and use it as the basis for their HAHTtalk language. This is more powerful than standard scripting languages, and can be offers programmers the ability to take existing Visual Basic skills and reuse them in a cross-platform Internet environment. As the HAHTsite Application Server is a separate application, HAHTtalk code does not need to be embedded in a web page, and can be stored as a series of external sub-routines, which are called from dynamic pages as required.

The HAHTsite IDE is links code development with web site management, and allows reuse of code “widgets”. A WYSWYG HTML page design tool is used to design static pages, which are linked to dynamic pages developed in the Visual Interface Designer. This allows rapid development of dynamic page elements, including database connections and input forms. Code builders construct either server-side HAHTtalk code or client side JavaScript, and the form builders include means of defining rules for JavaScript field validators. HAHTsite supports the SCC source control interface, and can use this to track and control team development in conjunction with any compliant repository tools.

PowerSoft PowerSite

PowerSoft’s PowerSite web application development environment is unusual in that it targets most of the common web servers, rather than just a specific system. By implementing a high-level object model, applications developed in PowerSite can be deployed on any of a range of web application environments, as well as transaction based middleware systems.

The PowerSite development environment is based on the Windows 98 controls, and uses several features taken from Internet Explorer 4.0. It also extends the design time controls introduced in Visual InterDev, and adds a series of controls based on the PowerBuilder client-server development environment’s Data Windows, so that you can build thin-client applications, ready for network computers. Links with the rest of the Power series of development tools are strong, and PowerSite can use Java beans, applications and applets developed in PowerJ, or can control the development of web enabled PowerBuilder applications produced in WebPB. An open development environment allows third parties to develop deployment engines for any web-applications environment.

As PowerSite is a cross-platform development tool, you can use it to build applications that mix ActiveX and Java, as well as using the latest HTML technologies in a WYSIWYG environment. All the major scripting languages are supported, and there are full debugging facilities for JavaScript, a well as any other language that uses the Microsoft Active Scripting engine.

Coming from parent company Sybase, PowerSite is very strong on team development, and uses a central repository to store pages and components. This allows you to “slurp” in any existing web applications and sites you may have, and manage their content using PowerSite.

Sybase’s PowerDynamo web applications server is included with PowerSite, as are deployment engines for most of the major environments currently in use - across most available operating systems. In addition, PowerSoft have arranged partnerships with a number of high profile web application development and deployment companies, including NetDynamics and, the recently-bought by Netscape, Kiva.