View source for CoCoA:HowTo:Contribute a CoCoA 4 function that calls the CoCoAServer

This article is intended to give contributors a rough overview of the process
of creating a new CoCoA 4 function that makes use of the CoCoAServer. There is
a CoCoA 4 part and a CoCoAServer part. 

== CoCoA 4 part ==
Create a new package file and place your function inside of it. Use the
following skeleton package file if unsure how to do this:

<pre>Package $mypackage -- New package name

Define MyFunction5(Operand, Info5) -- New function
  -- Insert your function code here

  -- Use "MyComputationIdentifer" within CoCoAServer.C to identify
  -- your function call
  Computation := "MyComputationIdentifier"; 

  -- Look at the code in "cocoa5.cpkg" for the meaning of "Info5" or leave
  -- it empty
  Info5 := Record();

  -- Actually call CoCoAServer and return its output;
  -- see text below for more details
  Return $cocoa5.OperationCommunication(Operand, Computation, Info5);
  -- Return $cocoa5.OperationCommunication(Operand1, Operand2, Computation, Info5);
EndDefine;

EndPackage;</pre>

Communication with the CoCoAServer is covered by the "cocoa5.cpkg" package. The
main interface is the "$cocoa5.OperationCommunication(...)" function. To
find out what types of operands you can pass to
"$cocoa5.OperationCommunication(...)" and how the communication with the
CoCoAServer actually works you have to look at the code in "cocoa5.cpkg": Read
at least the functions definitions of "$cocoa5.OperationCommunication(...)",
"$cocoa5.ExtendedInfo(X, Info)", and
"$cocoa5.ComputationRequestToDevice(Operands, Computation, Info5, D)".
Especially the function mentioned last is of interest as it gives an overview
of what types of operands already are supported. If your operands have a type
that is not mentioned there you will have to extend both the functions in
"cocoa5.cpkg" and the communication functions in "CoCoAServer.C" to pass
your operands through to the CoCoAServer. Communication is performed by sending
XML like sequences and you have to add new tags if necessary.

== CoCoAServer part ==
This part is covered in the article [[CoCoALib:Contribute#Contribute a new CoCoAServer function|Contribute a new CoCoAServer function]].

[[Category:HowTo Old]]
[[Category:CoCoA4]]