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[[IBM DB2]] (AP127)<br />
In the early 1980s, [[I. P. Sharp Associates]], which offered a highlyrich modifiedand version of IBMadvanced APL\360, introduced Shared Variables in their product offering. Many of the Shared Variable Processors available for IBM products were also written for Sharp APL, notably TSIO (called PJAM), AP124, AP126, and AP127. Further, as I. P. Sharp also offered [[IPSANET]] which allowed in-house clients of SHARP APL to be connected to the network, a Network Shared Variable Processor, or NSVP, allowed programs from one mainframe site to access another. NSVP predates the widespread usage of the Internet by five years.
Shared Variables were one technique used by APL implementors and vendors to increase the richness of the APL language, anddoing so without touching the core implementation. With the advent of more powerful personal computing, the exodus of the APL user community to smaller computers was inevitable. APL was first available on Z80 based hardware, later the original IBM PC, and today on the 32- and 64-bit Linux and Windows workstations. Although Dyalog APL included an implementation of shared variables for communication with the now-deprecated Microsoft Windows [[Dynamic Data Exchange|DDE]], it is interesting to note that only IBM continued to use Shared Variables as a means to supply new features to their versions of the APL2 language for non-mainframe computers.
Nearly all other APL vendors chose to implement new functionality, such as access to [[Linux]] and Windows native features, graphical user interface, presentation graphics, database management system interfaces, and so on, more directly in their respective versions of the APL language. In modern non-IBM APL implementations, the Shared Variable interface has been largely supplanted by COM, ActiveX, and .Net.
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