A disturbing trend has developed as of late. With the proliferation of multiple compression utilities, it seems that everyone has begun to create self-extracting archives (SEAs). While this is all-and-well, self-extracting archives add to the file sizes of files being transferred. While 10-20K for the self-extraction code isn’t much, it rapidly adds up over multiple transfers. In addition, for small files, often the use of self-extraction features cause the file to be larger than the original, uncompressed file.
WHAT IT DOES
DeSEA removes the overhead self-extraction code. What DeSEA does is first change the type and creator of the file to the program’s native format, rename the file from the self-extraction suffix to the native suffix, strip the resource fork of all the overhead code, and reset the finder flags. Since the compressed data is always stored in the data fork, no important data can ever be lost since the data fork is left completely intact. DeSEA can be run on a single file or on an entire folder of files. DeSEA is currently configured for the three most popular compression programs: Disk Doubler, Compact Pro, and StuffIt Classic/Deluxe. DeSEA is extensible as well, since new compession programs always seem to be emerging (see below).
EXTENSIBILITY
Although DeSEA is currently configured for only three archive formats, it is extensible. Within the DeSEA application are a number of “Dkey” resources. A template is included to make adding new ones a snap. Each resource is basically a set of rules about a resource type:
1) Item checked by default? (TRUE or FALSE) if TRUE, when DeSEA is launched, the convert item will be checked by default.
2) SEA creator.
3) SEA suffix. Currently, the typical suffix for self-extracting archives is “.sea”
4) Type for DeSEA’d archive.
5) Creator for DeSEA’d archive
6) Suffix for DeSEA’d archive (.dd, .cpt, .sit, etc.)
Note that a special type ‘****’ has been designated for archives that must be special-cased within the DeSEA application. Disk Doubler is currently the only existing example. If removing the self-extraction code from the archive is more than simply stripping off the resource fork and changing the type/creator, then it must be specially-handled from within the DeSEA application. If there’s an different archive format that you frequently encounter which fits this case, I’ll be happy to release a new version of DeSEA to deal with them. Just drop me a line.
CAVEAT
DeSEA has been tested on various Macintoshes under both System 6.0 and 7.0. DeSEA provides error checking at each step of the DeSEA process. If, for some reason, an error occurs during the DeSEA process, the file may not be fully converted and you will be notified of the error. (Most likely the archive is on a locked disk or a fileserver to which you do not have write permission.) In all such cases, though, the archive’s data will remain undamaged since all the archive data is placed in the data fork and only the resource fork is being modified. In any case, you should be able to open it from the respective archiveing program. At the very worst, you might have to change the type and creator.
SYSTEM 6 CAVEAT…
System 6.0.x seems to have a problem with applications other than the Finder which change the Finder flags of an application. If a file which is being DeSEA’d under Multifinder (6.0.x) is currently displayed in an open window, its flags may not be set properly if the file is moved. It is therefore advisable under System 6.0.x to close the windows of files being DeSEA’d. System 7.0 doesn’t appear to display this obnoxious behavior.
UPGRADING TO 1.1
System 7 users who wish to make use of the drag & drop features of DeSEA may have to rebuild the desktop before SEA’s may be dropped onto DeSEA.
FUTURE VERSIONS
I have received one request for implementing the DeSEA feature for SuperDisk! archives. Unfortunately, SuperDisk doesn't implement its self-extracting archives in the traditional manner and the conversion would be more than a simple removal of the resource fork (there's an extra header in the data fork for SEAs). If I receive more requests, I may persue the issue with Alysis, otherwise, c'est la vie.
In addition to the SuperDisk request, I've received requests for a UNIX version of DeSEA. This might get done in time for Christmas, depending on my work load, but it's in the works.
THANKS TO…
The beta-testers on my local BBS’s: Boston Computer Society, The Graphics Factory, and Tom’s BBS. Special thanks to Barry Wolman and Masatsugu Nagata (both for numerous bug reports), and to those who have sent me postcards (three countries and counting).
DISTRIBUTION INFORMATION
DeSEA is Freeware. Online services, bulletin boards, and user-groups may distribute DeSEA without restriction. Companies like Educorp, which make money on programs which I have deemed “free” must request permission, in writing, to distribute DeSEA.
If you find DeSEA useful, why not send me postcard of your place of business, hometown, school, or where you most recently vacationed. Bug reports, comments, and suggestions are always welcome either by US Snail or electronic mail.
Enjoy!
Ken Hancock
9C Jacqueline Road
Waltham, MA 02154-4979
AOL: khancock
Internet: kenh@eclectic.com
CIS: >INTERNET:kenh@eclectic.com
---------------
Version History
1.0 -- Initial release of DeSEA.
1.1 -- Support for DiskDoubler archives
added configuration menu
added support for AppleEvents
1.1.1 -- Maintenance release to fix potential problem with DiskDoubler archives.
