ServerOp

• User documentation
  • Outline
  • Virtual functions
  • Debugging the server

User documentation

Outline

ServerOpBase is the abstract class for an object representing an operation of the CoCoAServer. A concrete class must implement these functions (see below for a detailed description):

      ServerOpBase(const LibraryInfo& lib)
      void myOutputSelf(std::ostream&) const
      void myReadArgs(std::istream& in)
      void myCompute()
      void myWriteResult(std::ostream&) const
      void myClear()

The concrete classes representing the actual CoCoALib operations and their registrations are implemented in RegisterServerOps.C. See RegisterServerOps for the registration procedure.

Data members

The class should have as data members the input myIn.. and output variables myOut.. for the main function called by myCompute().

For example the class IdealGBasis has:

   PolyList myInPL, myOutPL;

For data types without a void constructor use auto_ptr, for example the class IdealElim has:

   auto_ptr<PPMonoidElem> myInElimPPPtr;

which is initialized in IdealElim::myReadArgs

   myInElimPPPtr.reset(new PPMonoidElem(t));

LibraryInfo

A LibraryInfo is a set of information common to a group of operations. The CoCoAServer prints the list of loaded (sub)libraries at startup.

    LibraryInfo(const std::string& name,
                const std::string& version,
                const std::string& group);

Example of definition of the function identifying a (sub)library:

    // sublibrary of CoCoALib for groebner related operations
    // by M.Caboara
    const ServerOpBase::LibraryInfo& CoCoALib_groebner()
    {
      static ServerOpBase::LibraryInfo UniqueValue("CoCoALib",
                                                   BuildInfo::version,
                                                   "groebner");
      return UniqueValue;
    }

Virtual functions

myCompute

This function should be just a straight call to a CoCoALib function, in particular with neither reading nor printing, using as input the class members called myIn.. and storing the result into the data members called myOut.., for example

  void myCompute() { ComputeGBasis(myOutPL, myInPL); }

myReadArgs

Read from GlobalInput, and store the arguments into myIn... In general this is the only difficult function.

myWriteResult

Print the result(s) (myOut..) in CoCoA-4 language assigning it into the CoCoA4 global variable whose name is stored in VarName4. For non-standard output just remember it simply is CoCoA-4 language, for example:

    void MVTN1::myWriteResult(std::ostream& out) const
    {
      out << ourVarName4 << " := [];";
      for (unsigned int i=0; i<myOutPP.size(); ++i)
        out<< "Append(" << ourVarName4<< ", " << PP(myOutPP[i]) << ");" <<endl;
    }

-- add example for "Record[..];" output from ApproxBBasis --

myClear

Reset all data members to 0. Right now (April 2007) it is only for cleaning the object right after it has been used, in future it might be called to reuse the object several times.

Debugging the server

If a function called by CoCoA-4 needs to be debugged this is the procedure to avoid dealing with sockets and fork under gdb.

• create from CoCoA-4 the input file ~/tmp/CoCoA4Request.cocoa5:

      $cocoa5.Initialize();
      MEMORY.PKG.CoCoA5.PrintOnPath := GetEnv("HOME")+"/tmp";
      MyFun5(X);
  

• In shell:

      src/server/CoCoAServer -d < ~/tmp/CoCoA4Request.cocoa5
  

• In gdb:

      file src/server/CoCoAServer
      r -d < ~/tmp/CoCoA4Request.cocoa5
      break CoCoA::error