Apple has kept the command-line job control mechanism minimalist while providing an API to develop more sophisticated tools built around it.

Xgrid's origins can be traced back to NeXT's Zilla application created by scientist Richard Crandall in the late 1980s.

Zilla was the first distributed computing program released on an end-user operating system and which used the idle screen-saver motif, a design feature since found in widely used projects such as Seti@Home.

[1][4] Zilla won the national Computerworld Smithsonian Award (Science Category) in 1991 for ease of use and good design.

One example of an Xgrid cluster is MacResearch's OpenMacGrid, where scientists can request access to large amounts of processing power to run tasks related to their research.

[12][13][14] In a report covering the announcement, Macworld cited Xgrid among the Unix features in "10 Things to Know about Tiger", calling it "handy if you work with huge amounts of experimental data or render complex animations".

[15] After Xgrid's introduction in 2004, InfoWorld noted that it was a "'preview' grade technology" which would directly benefit from the Xserve G5's launch later that year.

[16] InfoWorld commentator Ephraim Schwartz also predicted that Xgrid was an opening move in Apple's entry into the enterprise computing market.

It can also monitor the job status on demand by querying the controller, although it cannot track the ongoing progress of individual tasks.

[24][8] The controller is central to the correct function of an Xgrid, as this node is responsible for the distribution, supervision and coordination of tasks on agents.

[24] Xgrid is layered upon the Blocks Extensible Exchange Protocol (BEEP), an IETF standard comparable to HTTP, but with a focus on two-way multiplexed communication, such as that found in peer-to-peer networks.

BEEP, in turn, uses XML to define profiles for communicating between multiple agents over a single network or internet connection.