Updating connection-tracking records at a network edge using flow programming

A non-transitory machine readable medium storing a program for performing stateful services on a particular data message flow comprising a plurality of data messages including first and second data messages, the program for execution by a set of processing units, the program comprising sets of instructions for:

• at a router:
• generating, for the first data message that a set of service nodes needs to process, a connection tracker record to store (i) a current first global state value identifying a global state for a plurality of service nodes including the set of service nodes, and (ii) an action for the data messages of the particular data message flow;
• identifying, for the second data message in the particular data message flow, the connection tracker record;
• determining, for the second data message, that the current first global state value stored in the connection tracker record does not match the global state currently maintained for the plurality of service nodes;
• examining a flow programming (FP) table, which potentially stores new instructions for processing the particular data message flow, to determine whether a FP instruction is stored for the particular data message flow that specifies a new action for the particular data message flow that does not match the action stored in the connection tracker record;
• and
• when a FP instruction is stored that specifies the new action, updating the connection tracker record to reflect the new action for the particular data message flow, and updating the first global state value in the connection tracker record to the currently-maintained global state;
• and
• when a FP instruction that specifies a new action is not stored in the FP table for the particular data message flow, updating the current first global state value stored in the connection tracker record to the currently-maintained global state.