The invention relates to data processing apparatus and methods for method oriented invocation (MOI) of data processing service modules. MOI Adapters and methods interface compound messages with service modules that process them, advantageously reducing memory and processing time utilization. Compound messages may be progressively parsed and processed, identifying the constituent information items needed by a service module and invoking the service module when all needed information items are available, without using resources to maintain and process superfluous message data. Multiple service modules may be addressed by a single MOI Adapter.