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COPE - CORBA implemented in Perl


This documents describes the steps you take when writing a CORBA application in Perl using COPE.

First the basics: the laguage binding used.

Scalar types


The char type is represented as a 1-character perl string, like 'a'.


octet is represented as a perl number, like 200. We could equally well make octet be exactly the same as char.

Integer types

long and short are no problem. unsigned long might internally be stored as a double, but that should be invisible.

Floating-Point types

Perl has those as well.


Structures are represented as blessed hashreferences. They inherit from CORBA::_Struct which implements a generic constructor called new, taking key,value pairs.

An example:

    #   struct MyStruct { // IDL
    #       boolean             simple;
    #       sequence <octet>    list;
    #   }
    package MyStruct;
    my $structvar = new MyStruct( simple => 1, list => [0,1,2] );

Every structure also has a TypeCode defined called _tc (in the appropriate package). In the example case, the typecode would be called $MyStruct::_tc


A sequence is represented as an unblessed array reference, with one exception:

octet sequences are represented as a perl string, because they tend to be used for blob-like data.


Are also represented as unblessed array references, also with one exception: char arrays, which are again perl strings.

What do people think of these exceptions to the rules?


Are subs with an empty prototype, declared in the appropriate package.


Are plain scalars.


I haven't looked at them yet (haven't needed them either)


Are Perl objects (blessed references)


Are Perl objects


Are Perl classes. This means a package and an @ISA array.


Are Perl methods


Will be a Perl object.


Are Perl classes inheriting from Experimental::Exception


I now favour the choice the Java people have made: a method taking zero or one extra arguments, for getting or setting the attribute. This looks the most readable to me.

Parameter passing


All types are already scalar in nature, so can be passed as-is. The number of arguments to a method are always exactly as in the IDL.


All non-reference types (numbers and strings) need to be fitted with a \ and can't be literals.


Same as for inout. note: You need to supply an empty anonymous array or hash for sequences, structs or arrays.

Objects need a scalar reference.

Working with TypeCodes

The TypeCodes for basic types are predefined and have names like $CORBA::_tc_boolean All non-basic types have their TypeCode stored in $package::_tc Custom TypeCodes can be built using functions like _create_struct_tc()

Server side

When implementing a server, we need three logically seperate classes:

The implementation of your object

This could be an existing class which you decide to give a shiny new CORBA wrapper

A generated Skeleton class

This is what gets called by the ORB. It is responsible for decoding method arguments and calling the method

A mapping class

The Mapping class provides the mapping between known method names the skeleton class uses and the possibly unknown names in your implementation class.


Copyright (c) 1997 Lunatech Research / Bart Schuller <> See the file "Artistic" in the distribution for licensing and (lack of) warranties.

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