These two Tcl modules implements a high-level interface to the DISQUE distributed message broker. The modules abstracts most of the API, as examplified in the following code snippet.
package require disque
set d [disque -nodes localhost]; # Connect to localhost only.
set id [$d addjob -async /queue test]; # Enqueue a job
lassign [lindex [$d getjob /queue] 0] queue id body; # Get it back
$d ackjob $id; # ACK it as done.
The programming interface for the main disque module happens through a single
command called disque, which will connect randomly to one of the nodes
specified as part of its arguments and return an identifier for the connection.
The remaining of the programming interface is loosely based on Tk, meaning that
the identifier returned after connection is also a command with a number of
sub-commands to communicate with the DISQUE node and/or close the connection.
The module automatically provides a wrapper for any DISQUE command, thus providing forward compatibility as or if the API will evolve. However, most of the DISQUE API has been wrapped through Tcl-friendly commands. Most of the wrapping involves the introduction of dash-led options that will directly map to the optional parameters of the DISQUE API. For example, calling the following:
$d addjob -async -replicate 3 /queue test
would lead to sending the following DISQUE command to the node:
ADDJOB /queue test 1000 REPLICATE 3 ASYNC
Note that, in that very special case, a default timeout of 1000 is automatically
added, which can be otherwise controlled by the -timeout option. To this
regard, the ADDJOB implementation is the only one that deviates from this
1-to-1 mapping between the optional paramaters of DISQUE and the dash-led
options. This decision was taken for the command to better respect the Tcl
conventions. Note that the options are placed directly after the name of the
command, again to better respect the Tcl coding conventions.