Delphi 97

Delphi 97 also has a number of facilities for server-side operation, the most interesting being Web Server. With this you can build a custom DLL that resides on the server and communicates directly with the server proper through ISAPI and NSAPI, Microsoft and Netscape's Web server interface protocols. Creating a Web Server project is easy - you just specify this type of project and then use the new Delphi controls that support server-side operation. These include THTTPDispatcher, a control that lets you set up multiple URIs (universal resource identifiers) and associate them with the corresponding number of event handlers. When a client requests a particular URI, such as 'SALESSIMONJAN', the THTTPDispatcher component checks if it has a corresponding handler. If so, the handler is called, passing it the full client request information. The handler can then choose to handle the request or ignore it, setting a flag as appropriate.

Other non-visual controls associated with Web Server projects let you create on-the-fly HTML code, format tables, produce result sets, and so on. It's a clever extension of the Delphi programming paradigm.

Ever since Delphi 1, people have whinged about the size of the resulting executables. The minimum size of an EXE file is around 150Kb, and it's much more if you use data-aware controls. This isn't so bad if you're selling a single commercial app, but if you're distributing several Delphi-based programs, the user will lose a lot of hard disk space since every app will contain its own copy of the VCL library. Also, if you're a shareware author trying to get your app distributed on a magazine front cover, a hefty executable can mean your program is rejected as there's not enough room for it on the disk.

To address these problems, Borland has introduced the 'package'. This is a collection of one or more VCL controls rolled up into a dynamic link library, which is referenced by a Delphi app. In my tests, a 150Kb program shrank to less than 13Kb, and a 500Kb data-aware app shrank to 16Kb. This means you can get several Delphi programs on one or two floppies, even allowing for the size of the DLLs.

Packages can be switched on or off through a check box in the Project Options dialog. Rather than putting the entire VCL library into one huge DLL, Borland has split things up so that data-aware components go into one package, Internet components in another, and so on. This reduces the amount of code you need to ship even further.

There's one potential snag. Delphi 97 lets you change the contents of any particular package, so that when you deploy your app you can't reasonably stuff a bunch of non-standard package DLLs into the Windows system directory for fear of giving another app a nasty surprise. Similarly, you shouldn't expect that any package DLLs you find in the system library are standard issue. However, packages still make sense if you're supplying several Delphi apps - just be sure to put the packages you need into the same directory as your executables.

There are many other small changes. The Component Palette now includes a 'splitter' (for putting a divider onto a form) and the long-awaited Animation control. New VCL components give access to the Toolbar and to the Coolbar - these are user-interface enhancements built into the Windows Common Controls DLL. An example of a Coolbar is the collection of moveable, resizable control bars seen at the top of the Internet Explorer window (IE 3 or later).

Two new dialog controls are provided for loading and saving picture files, complete with preview windows, and Delphi 97 has the same collection of Internet-enabled controls that arrived in Delphi 2.01. Sample programs are provided to get you up and running with HTML clients and FTP.