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Optically Synchronous/Asynchronous Invocation of the System Service

IP.com Disclosure Number: IPCOM000080003D
Original Publication Date: 1973-Oct-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 57K

Publishing Venue

IBM

Related People

Hall, HA: AUTHOR

Abstract

In a system or language having both synchronous and asynchronous communication and control passing facilities, system services (as well as user programs) are written to be invoked either synchronously or asynchronously, at the option of the invoker or his controlling agent.

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Optically Synchronous/Asynchronous Invocation of the System Service

In a system or language having both synchronous and asynchronous communication and control passing facilities, system services (as well as user programs) are written to be invoked either synchronously or asynchronously, at the option of the invoker or his controlling agent.

Let the system control passing instructions be named "invoke synchronously" (IS) and "invoke asynchronously" (IA).

If program P1 invokes P2 using IA, then both programs are permitted to execute concurrently. Passing of data between P1 and P2 is through one or more communication buffers (CBs), which are in the form of queue elements, stack entries, control blocks, or hardware registers. CBs either are identified as arguments of IA, or are commonly addressable. If P1 expects explicit results from P2, then P1 must issue the instruction "synchronize return" (SR) to receive them.

SR references a CB and names the invoked program.

If P1 invokes P2 using IS, then P1 is suspended while P2 executes. Upon completion of P2, control is returned to P1 along with any expected results.

A service program which takes advantage of these concepts appears in Fig. 1A.

If the system control passing facilities do not utilize a common communication interface--for example, if CB1 in Fig. 1B is a control block and CB2 is a register--the service must test an input parameter or system variable to determine the appropriate means for returning results.

Figs...