Part 7: Application deployment, documentation, and supportAll three tools have one tremendous advantage over conventional development environments: applications are truly portable. No compilation or other preprocessing is necessary. You just move the source code (or in the case of MetaCard, the binary stack) over to the target system and run it. Of course, the interpreter must have been built and installed before this will work.
With dtksh, presumably this engine will be installed as part of the normal operating system installation. Unfortunately, this portability only extends to systems that will be upgraded to OS releases that include the COSE desktop environment. Many systems, probably including the majority of SPARC systems running SunOS 4.1.X, won't be upgraded to run CDE and so won't be able to use dtksh. And since the dtksh engine can't be redistributed free of charge as is the case with Tcl and MetaCard engines, it is not possible to include the dtksh engines in distributed products just in case the customer does not already have it. This means that it is impractical to build many kinds of commercial products with dtksh, since the potential market is so severely limited.
The MetaCard engines are prebuilt for all supported platforms. After this executable is placed in the user's PATH, MetaCard stacks can be run directly from the command line or by double clicking on them with a file manager. Deployment of Tcl/Tk applications is similar, though in some cases the binaries will need to be compiled for each target platform.
Of the three environments only MetaCard has encryption built in to password protect stacks. This protection makes it possible to distribute MetaCard applications without the concern that an end user can modify a script or copy some or all of it for their own use.
A final potential advantage of Tcl/Tk and MetaCard over dtksh is portability to non-UNIX platforms. Tcl/Tk is available on the Macintosh and MS-Windows, though it doesn't have native look and feel on these systems. MetaCard is available on Windows 95/NT and has native look and feel on all platforms. Products that are source-compatible with MetaCard have been available on the Mac and Windows for years, including HyperCard, SuperCard, Oracle Media Objects, and Object Plus.
It is very unlikely that dtksh will ever be available on non-UNIX platforms. Although the Tcl/Tk and MetaCard executables are larger (900K and 1.3M respectively), they are self-contained. dtksh, on the other hand, is only 800K, but requires many additional dynamic libraries totaling over 2MB. Porting the required Xt and Motif libraries to other OSs would be very difficult, and their large size would make dtksh non-competitive in these environments.
Documentation and supportTcl/Tk comes with a man page describing basic functionality, but most developers will want to purchase the book published by Addison Wesley "Tcl and the Tk Toolkit" (ISBN 0-201-63337-X). The book is comprehensive and indexed, but lacks important reference information such as tables listing all of the widget properties and the built-in Tcl commands. Instead, this information is available in an on-line form, presumably to reduce the degree to which the book becomes obsolete as the toolkit evolves. Technical support for resolving problems with Tcl/Tk is generally acquired through the comp.lang.tcl newsgroup or from an experienced friend or colleague.
The standard of dtksh documentation is J. Stephen Pendergrast's "Desktop KornShell Graphical Programming". Technical support for dtksh will come from the vendors, which will vary greatly depending on the vendor and on the support plan purchased with the OS.
MetaCard comes with extensive on-line documentation in the form of MetaCard stacks. Though no index is provided, the documentation can be search with a full-text search, and extensive hypertext links are included. Hardcopy documentation is available at extra cost. In addition, since MetaTalk is compatible with HyperTalk, any of the dozen or so books on HyperCard can be used as scripting language reference material. MetaCard technical support is available free of charge via email from MetaCard Corporation.
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