Web development demands a diverse set of skills. Significant sites involve authoring, programming and database access, with the results delivered through HTML, a mark-up language devised for viewing and linking formatted documents on multiple platforms. It makes a curious development platform, and presents a bewildering set of choices to the developer. The aim of Visual InterDev is to provide an integrated solution, gathering these diverse elements into a single, manageable project.
Visual InterDev is a tool for developing web sites for Microsoft Internet Information Server running on Windows NT Server. It also works with Microsoft's Personal Web Server for Windows 95 and it makes use of the Front Page server extensions. In short, this is a product for those committed to Microsoft's web server technology. You can still create browser-independent applications, although to do so requires careful avoidance of certain features.
At the heart of Visual InterDev is a feature called Active Server Pages.
This will be easiest on a corporate intranet, where the workstations and browsers are specified centrally.
Visual InterDev runs inside Microsoft's Developer Studio, the integrated development environment also used by Visual C++ and Visual J . To use it requires an active connection to a web server. When you create a web project, files are created on the web server with working copies on your local hard disk. Editing takes place on the working copies. The server is updated when the project is saved. An advantage of this technique is that several developers can work on a web project simultaneously.
Web projects are viewed and managed through a workspace window, which displays all the project's files in a tree view. Double-clicking a file opens it for editing. Project files can include images, sounds, database connections, ActiveX layouts and Office documents as well as ASP and HTML pages, and Visual InterDev will choose an appropriate editor according to the file type. Testing a site is a matter of previewing it in a browser, which is easily done since Internet Explorer 3.0 is a component within Developer Studio.
Managing the user
One of the problems of web development is that users expect to jump at will from page to page and site to site. This is fine for viewing documents, but breaks down when the site involves such things as controlled database access or on-line shopping. Visual InterDev attempts to make navigating a web site more like running a conventional application. It includes the concept of a session, which begins when the user first requests a URL on your site, and ends when a page has not been requested or refreshed for a specified timeout period.
You can write code that executes when a session begins or ends, and track the actions and preferences of the current user using session properties.
The key to this is a special file called Global.ASA which is loaded at the start of every session. For example, this might open a database connection for the current user. The system works best with browsers that support and allow cookies, identification files that are downloaded to the user's computer. If cookies are not available, Visual InterDev can still track a user moving within the site, but not if he or she leaves the site and then returns immediately.
Despite Microsoft's best efforts, relatively few sites use client-side ActiveX controls. This is for excellent reasons. Most ActiveX controls work only on Windows, and many are nervous about security risks. Server-side ActiveX is different, since it does not require the client to download any executable content. Visual InterDev scripts can use a built-in Server object to run code on the server through OLE automation. A key use is database access through the ActiveX Data Object (ADO), an automation interface to ODBC data sources via OLE/DB. Other supplied server components include an advertisement rotator, a TextStream object for file input and output, and a BrowserType object that reports the capabilities of the current browser.
Data access through ADO will look familiar to Visual Basic developers.
You can create updateable recordset objects based on SQL queries, and use the recordset's properties and methods to navigate its rows and field values. Provided that the data source is correctly configured on the server, it is relatively easy to provide dynamic database access on a web page.
Since you have full programmatic control, you can change the whole appearance of a page according to values stored in a database. One of the Visual Interdev examples displays products with images, descriptions and prices, all of which are stored in a relational database. Visual Interdev projects have a Dataview tab, which shows the structure and content of database connections and provides visual tools for accessing the data.
Wizards and add-ons
Visual InterDev contains several wizards and helper applications to ease development. The Web Project wizard starts a skeleton web project, although it does not build a set of pre-defined pages in the same way Front Page does. The script editor is a rather poor affair that lets you build VB Script or JScript. You can insert ActiveX controls into web pages, and control them with VB Script. A particularly useful ActiveX control is the HTML layout control, which allows you to build part of a page in the same way as you would a Visual Basic form, writing code to respond to events such as a click on an image map. The reservation here is simply that ActiveX is only available to a section of the web community. Another type of ActiveX control, called design-time ActiveX, is used as a kind of wizard to automate editing procedures.
Three smaller applications come with Visual InterDev. Image Composer is a surprisingly capable image editor which treats images as a collection of sprites. Music Composer generates MIDI files intended to provide background sounds. Music is composed by selecting a combinations of styles, moods and effects, and Microsoft claims that reward ensures that every composition is different. Media Manager is a way of managing and categorising multimedia files on disk.
Visual InterDev says a lot about Microsoft's attitude to Java. There is no problem with using Java in a Visual InterDev project, and since Visual J shares the same development environment, it is actually rather easy. But Java is not at the heart of this product. For data access you are pointed to ADO, not JDBC. For components, the emphasis is on ActiveX, not Java applets.
Assessing Visual InterDev
Visual InterDev is an appealing product which is targeted well. It lets you build sophisticated, interactive web sites using familiar elements such as Developer Studio and Visual Basic Script. It is particularly powerful in environments such as corporate intranets, where ActiveX controls and Internet Explorer can be deployed in a controlled manner. Those developing for the wider Internet may also find it useful, if they are careful to avoid client-side VB Script and ActiveX components, or willing to accept restricted compatibility.
Visual InterDev is part of the Visual Studio 97 bundle, or can be obtained separately. Version 1.0 costs $399. Microsoft at www.microsoft.com or 0345 002000
VERDICT: Visual InterDev
An appealing product which is targeted correctly
- Integration of HTML, scripting and databases
- Rich features and helper applications
- Familiar and easy for Visual Basic developers
- Crude script editor
- Difficult debugging
- Compatibility and security of client-side ActiveX.
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