Hi On Mon, Jul 26, 2010 at 9:14 PM, Benjamin Eberlei <kont...@beberlei.de> wrote: > Hello everyone, > > i want to propose the development of a CouchDB Storage Tiein for the > Workflow Engine. It would be a considerable improvement over the > Database backend, for various reasons:
Maybe abstract it to have easy tie ins for other document oriented databases? > > 1. Several variables are saved as PHP serialize() output in LONGTEXT > fields in both the Workflow and Execution parts of the Engine. This is > rather problematic (and ugly). Workflow just has many "unrelational" > parts such as node configuration, execution state/variables and thread > information. CouchDB could just nest them as sub-objects in JSON. +1, and also return JSON constructs for potential use in view layers > > 2. Database backend uses serialized php data for Execution::$variables > and Execution::$waitingFor, both variables that are interesting for > querying the set of existing workflows. Views can be easily written > using any of the two as keys to select for. Yes! > > 3. Both a workflow and an execution could be saved in a single document > each. > > Why a workflow? Workflows are never updated, only saved with a new ID. > Otherwise you could seriously destroy currently existing executions of a > changed workflow. Therefore no problems exists with read/write > contention or version conflicts. > Fair enough, is your use-case involving "long-lived" workflows? About the execution, I see MongoDB as an attractive alternative too, because it allows updates in place for a single key/field, further minimizing the overhead for tracking this execution part > Why an execution? It has to be resurrected from persistence completely > in any case, the nested data is never of any interest in an incomplete > context. You always need the whole data. Indeed, at least for as far I dived into and understand the workflow component at this stage > > What do you think of the idea? Is there interest in this development? I think so, but I am biased towards doc-oriented backends anyway my 0.02€ Paul
