...trans-session execution of workflow that most people would express in flowcharts with crap like BPEL is better encapsulated in serialized continuations. Neither of which scale to web-sized loads. The alternative is, of course, saving a 'pointer' or some-such state information which is then either loaded into a honking IF statement or a sub-language parser.
None of this should be necessary. Programmatic access to stacks, heaps & scope is something that is all technically possible in assembly.