shim (software)

[James Knight, MLIS]

 From "The Jargon File"
[http://www.jargon.8hz.com/html/index.html]
...The 4.0.0 version was published in September 1996 as the third edition
of The New Hacker's Dictionary from MIT Press (ISBN 0-262-68092-0).

shim: n.
1. A small piece of data inserted in order to achieve a desired memory
alignment or other addressing property. For example, the PDP-11 Unix
linker, in split I&D (instructions and data) mode, inserts a two-byte shim
at location 0 in data space so that no data object will have an address of
0 (and be confused with the C null pointer). See also loose bytes.
2. A type of small transparent image inserted into HTML documents by
certain WYSIWYG HTML editors, used to set the spacing of elements meant to
have a fixed positioning within a TABLE or DIVision. Hackers who work on
the HTML code of such pages afterwards invariably curse these for their
crocky dependence on the particular spacing of original image file, the
editor that generated them, and the version of the browser used to view
them. Worse, they are a poorly designed kludge which the advent of
Cascading Style Sheets makes wholly unnecessary; Any fool can plainly see
that use of borders, layers and positioned elements is the Right Thing (or
would be if adequate support for CSS were more common).

  ... "The first PDP-11s (the 11/15 and 11/20) shipped in 1970 from DEC;..."

For what it's worth:

magic cookie: n.
[Unix; common]
...
2. An in-band code for changing graphic rendition (e.g., inverse video or
underlining) or performing other control functions (see also cookie). Some
older terminals would leave a blank on the screen corresponding to
mode-change magic cookies; this was also called a glitch (or occasionally a
turd; compare mouse droppings). See also cookie.

"older terminals" being those dumb tubes connected to mini- and main-frame
computers, vintage late sixties, early seventies -- predating the common PC
web browser by at least twenty years.

Cheers,

-jk


At 08:58 PM 12/20/03, you wrote:
>Heard in conversation tonight:
>
>"... a shim between the DVD driver and the software for reading the
>disk."
>
>When asked, the speaker defined this use of "shim" as "a piece of
>software that sits between two pieces of software that normally
>communicate directly with each other." It usually operates
>transparently, so that neither of the two other pieces of software*
>"knows" that it's there, but "thinks" it's communicating with the other
>one normally.
>
>I hadn't heard this usage before. A Google search finds around 28k hits
>of
>"shim" and "software" in the same text, of which the first relevant one,
>is #10,
>http://archnet.caup.washington.edu/00Archnet%20Home/3.Software/0.default.html
>(University of Washington, Department of Architecture: ARCHNET Student
>Download Software):
>
>
>What is the "Keyserver Client"?
>
>The management mechanism that keeps track of the number of licenses of
>each title that are in use is a "software metering" system. Most of our
>software is metered by a system called "KeyServer". This "shim" software
>sits between the application and the network, checking licenses in and
>out as you work. "Keyserver Client" is the name of the application
>(under Windows, on a Mac it is an extension) that provides the necessary
>services. Therefore, you must install the Keyserver Client first, prior
>to installing or running any of the other applications.
>
>-- Mark A. Mandel
>    Linguistic Data Consortium, University of Pennsylvania