A method and computer program product for performing a plurality of processing operations. A plurality of processor nodes each include one or more operational instances. Each processor node includes criteria for generating its operational instances. The processor nodes are linked together in a directed acyclic processing graph in which dependent nodes use data from the operational instances of upstream nodes to perform a node-specific set of processing operations. Dependency relationships between the processor nodes are defined on an operational instance basis, where operational instances in dependent processor nodes identify data associated with, or generated by, specific upstream operational instances that is used to perform the node-specific set of operations for that dependent operational instance. The processing graph may also include connectors nodes defining instance-level dependency relationships between processor nodes.