    class
    	DATA_RESOURCE_FACTORY_IMPL

    General
    	cluster: transfer
    	description: "Implementation of data resource factory"
    	create: make

    Ancestors
    	ANY

    Queries
    	address: STRING_8
    	default_service: STRING_8
    	is_address_correct: BOOLEAN
    	is_address_set: BOOLEAN
    	is_service_supported: BOOLEAN
    	resource: DATA_RESOURCE
    	service: STRING_8
    	url: URL

    Commands
    	create_resource
    	set_address (addr: STRING_8)
    	set_default_service (service_name: STRING_8)

    Constraints
    	default service specified