Programming in FORTRAN

In this section, we explain how to program OmniRPC in FORTRAN. If you want to know more details about APIs, see Section FORTRAN API .

A simple example in FORTRAN

Create remote executable program

Client program in FORTRAN

An example of an asynchronous call in FORTRAN

A simple example in FORTRAN

main.f:
      double precision a(10),b(10),r
      do i = 1,10
         a(i) = i
         b(i) = i+10
      end do
      call innerprod(10,a,b,r)
      write(*,*) 'result=',r
      end

ip.f:
      subroutine innerprod(n,a,b,r)
      integer n
      double precision a(*),b(*),r
      integer i
      r = 0.0
      do i = 1,n
        r = r+a(i)*b(i)
      end do
      return
      end

Let's set this program to call the innerprod subroutine with OmniRPC.

Create remote executable program

As in a C program, we create a program which executes a subroutine on remote hosts. So, we define an interface to innerprod. We set the module name as f_innerprod, and the function name as innerprod.

Module f_innerprod;

Define innerprod(IN int n, IN double a[n], IN double b[n],
        OUT double result[1])
Calls "Fortran" innerprod_(n,a,b,result);

The argument which specifies the array size must be a scalar variable. The double precision type in FORTRAN is "double", the real type is "float". If you directly call a FORTRAN function with calls, you specify "Fortran". Calling a function can mangle the function name in FORTRAN. Usually, in the case of the FORTRAN compiler, a mangled name is a name to which "_" has been added. Please pay attention to whether a function name contains "_"; if it is mangled, add "__" in g77 (gcc).

This definition is the same as the above definition. As scalar variable is taken as the address pointer.

Module f_innerprod;

Define innerprod(IN int n, IN double a[n], IN double b[n],
        OUT double result[1])
{
    innerprod_(&n,a,b,result);
}

Generate OmniRPC's remote executable modules from this IDL file. We name this IDL file f_ip.idl.

$ omrpc-fc f_ip.idl ip.f

When you run this command, the remote executable program f_ip.rex is generated. To register with omrpc-register, the method is the same as in C language.

$ omrpc-register -register f_ip.rex

The command omrpc-fc, it compiles FORTRAN program with f77. If you want to use another compiler, use the "-fc" option. For example, if you want to use the intel Fortran compiler of ifc, run the following command.

$ omrpc-fc -fc ifc f_ip.idl ip.f

Client program in Fortran

And now, change the client program main.f to call the remote executable program with OmniRPC.

      double precision a(10),b(10),r
      call OMINRPC_INIT
      do i = 1,10
         a(i) = i
         b(i) = i+10
      end do
      call OMNIRPC_CALL("f_innerprod*",10,a,b,r)
      write(*,*) 'result=',r
      call OMNIRPC_FINALIZE
      end

This program initializes with OMNIRPC_INIT and calls by OMNIRPC_CALL. Please keep in mind that the entry name which is specified by OMNIRPC_CALL should have "*" at the end of the name which is defined on the interface. You should add "*" to the end of strings which are obtained with OmniRPC, such as the module name and host name. OmniRPC considers "*" to be a string terminator in OmniRPC's Fortran API.

Using omrpc-fc to compile this file.

$ omrpc-fc main.f

An asynchronous call in FORTRAN

Finally, we show an example which is written in FORTRAN. this example is also shown in the section Parallel programming with OmniRPC .

      double precision res(10)
      double precision x
      integer ireqs(10)
      call omnirpc_init
      x = 0.0
      do i = 1, 10
         call omnirpc_call_async(ireqs(i),'calc_sin*',x,res(i))
         x = x + 1.0
      end do
      call omnirpc_wait_all(10,ireqs)
      do i = 1, 10
         write(*,*) 'res(',i, ')=',res(i)
      end do
      call omnirpc_finalize
      end