Loading IDL

All the CORBA support provided by OiL is based on interface and typing information. OiL stores all this information in a internal type repository, which implements a CORBA Interface Repository. Once an IDL interface definition is stored in this repository, OiL is able to create servants and proxies with that interface. OiL provides three ways to load an interface or type, as described below.

IDL Specifications

The most common way to load interface definitions is to load an IDL specification using method loadidl(idlspec) e loadidlfile(filepath) of CORBA brokers. In this case, the IDL specification is parsed to produce descriptions that are stored in the internal type repository, as illustrated in the example below.

require "oil"

oil.main(function()
  local broker = oil.init()
  
  broker:loadidl[[
    interface Hello {
      void say();
    };
  ]]
  
  broker:writeto("hello.ior",
    broker:tostring(
      broker:newservant(hello, nil, "Hello")))
  broker:run()
end)

Remote Interface Repository

An alternative to the use of IDL specifications is to acquire the interface definition from a remote CORBA Interface Repository (IR) that already contains them. This can be done by method setIR(ir_proxy) of CORBA brokers. This method receives as argument an OiL proxy to the remote IR. Whenever OiL finds the name of a interface or type that it does not known, it then checks this remote IR and reads the definition. However, this is only done for the first time. Once OiL learns about an interface, it does not read its definition again, even if the original definition changes in the remote IR. The code below shows how to setup the remote IR.

require "oil"

oil.main(function()
  local broker = oil.init()
  
  -- create proxy for a CORBA IR
  -- and set it as the remote IR
  broker:setIR(       
    broker:newproxy(  
      oil.readfrom("ir.ior")))
  
  broker:writeto("hello.ior",
    broker:tostring(
      broker:newservant(hello, nil, "Hello")))
  broker:run()
end)

CORBA brokers also provide the method getIR() to get the current remote IR being used. Furthermore, the OiL's internal type repository also implements the CORBA IR interface, therefore, all interface and type definitions can be accessed remotely by CORBA IR clients. In particular, another CORBA broker can be configured to retrieve definition from the internal type repository of another CORBA broker. To get the servant of the internal IR, use method getLIR() of CORBA brokers.

Lua Constructors

Finally, another way to provide interface and type descriptions is to create them using the constructors provided by module oil.corba.idl and register them in the internal IR. For a description of these constructors, check section Value Mapping. The code below shows how to create and register descriptions of the Hello interface in the internal type repository.

require "oil"

oil.main(function()
  local idl = require "oil.corba.idl"
  local broker = oil.init()
  
  broker.types:put(
    idl.interface{
      defintions = {
        say = idl.operation(),
      }
    }
  )
  
  broker:writeto("hello.ior",
    broker:tostring(
      broker:newservant(hello, nil, "Hello")))
  broker:run()
end)