Websphere MQ, formerly known as MQ (message queue) series, is an IBM standard for program-to-program messaging across multiple platforms.
It allows independent and potentially non-concurrent applications on a distributed system to communicate with each other. MQ is available on a large number of platforms (both IBM and non-IBM), including z/OS (mainframe), OS/400 (IBM System i or AS/400), UNIX (AIX, HP-UX, Solaris), HP NonStop, OpenVMS, Linux, and Microsoft Windows.
More details: http://en.wikipedia.org/wiki/Websphere_MQ
