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GAP 4.8.9 installation with standard packages -- copy to your CoCalc project to get it

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1
<Chapter Label="SCSCPmessages">

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<Heading>Message exchange by &SCSCP;</Heading>    

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To ensure the message exchange as required by &SCSCP; specification, the 

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&SCSCP; package extends the global record <C>OMsymRecord</C> from the 

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&OpenMath; package with new entries to support &scscp1; and &scscp2; 

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content dictionaries (<Cite Key="scscp1cd"/>, <Cite Key="scscp2cd"/>), 

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and also service-dependent transient private content dictionaries 

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(see Chapter <Ref Label="Server"/> for details about transient content 

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dictionaries). It also overwrites some &OpenMath; functions by their 

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extended (but backwards compatible) versions, and adds some new 

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&OpenMath;-related functions to send and receive &SCSCP; messages, 

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documented below.

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<P/>

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Note that functions documented in this chapter belong to the middle-level 

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interface, and the user may find it more convenient to use functions 

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developed on top of them and explained in next chapters.

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<Section Label="SCSCPclient">

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<Heading>Communication with the &SCSCP; server</Heading>

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<#Include Label="StartSCSCPsession">

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<#Include Label="OMPutProcedureCall">

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<#Include Label="SCSCPwait">

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<#Include Label="OMGetObjectWithAttributes">

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</Section> 

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<Section Label="SCSCPserver">

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<Heading>Communication with the &SCSCP; client</Heading>

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<#Include Label="OMPutProcedureCompleted">

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<#Include Label="OMPutProcedureTerminated">

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</Section>

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<Section Label="SCSCPsession">

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<Heading>Example: &SCSCP; session</Heading>

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In the following example we start an &SCSCP; session and perform ten

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procedure calls in a loop before closing that session. Note that we

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demonstrate the usage of the session ID <C>sid</C> and the function 

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<C>RandomString</C> from the &OpenMath; package to produce some unique 

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call identifier.

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The call ID is a mandatory attribute for any procedure call, however, 

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it is not nesessarily random; for example, it may be just a string 

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with the number of the procedure call.

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<Example>

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<![CDATA[

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gap> stream:=InputOutputTCPStream( "localhost", 26133 );

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< input/output TCP stream to localhost:26133 >

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gap> sid := StartSCSCPsession( stream );

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"localhost:26133:5541"

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gap> res:=[];

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[  ]

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gap> for i in [1..10] do

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>     OMPutProcedureCall( stream, "WS_Factorial", 

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>       rec( object := [ i ], 

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>        attributes := [ [ "call_id", 

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>          Concatenation( sid, ":", RandomString(8) ) ] ] ) );

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>     SCSCPwait( stream );

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>     res[i]:=OMGetObjectWithAttributes( stream ).object;

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> od;

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gap> CloseStream(stream);

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gap> res;

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[ 1, 2, 6, 24, 120, 720, 5040, 40320, 362880, 3628800 ]

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]]>

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</Example>

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Also note the usage of <Ref Func="SCSCPwait"/> to wait

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until the result of the computation will be available from 

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<C>stream</C>.

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<P/>

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In this example we assumed that there is an &SCSCP; server running 

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at <C>localhost</C>, port 26133. In the next chapter we will explain

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how to configure and run a &GAP; &SCSCP; server and how to interrogate

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it from a &GAP; client to learn about its functionality. After that,

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we will proceed with the &SCSCP; client functionality for the end-user.

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</Section>

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</Chapter>

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