The following script shows how you can call the FOP server from a Delphi  program:

uses  ...... IdHTTP;
...
var
lHTTP: TIdHTTP;
response:TMemoryStream;
source: TMemoryStream;
xml:AnsiString;
begin

// input xml data
xml:='<?xml version="1.0" encoding="iso-8859-1"?> <departments><department><departmentName>R&amp;D</departmentName> <person> <name>John Schmidt</name> ';
xml:=xml +'<address>Red street 3</address> <status>A</status> </person> <person> <name>Paul Bones</name> <address>White street 5</address> <status>A</status> ';
xml:=xml +'</person> <person> <name>Mark Mayer</name> <address>Blue street 5</address> <status>A</status> </person> <person> <name>Janet Black</name> ';
xml:=xml +'<address>Black street 8</address> <status>I</status> </person></department><department> <departmentName>Sales</departmentName> <person> ';
xml:=xml +'<name>Juan Gomez</name> <address>Green street 3</address> <status>A</status> </person> <person> <name>Juliet Bones</name> <address>White street 5</address> ';
xml:=xml +' <status>A</status> </person></department></departments>';


lHTTP := TIdHTTP.Create(nil);
response:= TMemoryStream.Create;
source:= TMemoryStream.Create;

// put xml string into a Stream
source.WriteBuffer(Pointer(xml)^, Length(xml));

// call server
lHTTP.Post('http://localhost:8087/J4LFOPServer/servlet?TEMPLATE=departmentEmployees.fo', source,response);

// save to PDF file
response.SaveToFile('output.pdf');


source.free;
response.free;
lHHTP.free;


end;