Modelling Checkin-Checkout using locks

Andreas Jung wrote: > Hi there, > > I am currently thinking about ways how to model a reliable > checkout-checkin scenario with XML documents. > > In an older SGML CMS system that we build, we implemented the > procedure roughly like that: > > - user chooses a document in the CMS and clicks on CHECKOUT - > CHECKOUT copy the document to a private area of the user - CHECKOUT > will lock the original file (reads allowed, write forbidden) - user > edits the the copied content - user performs either a CHECKIN which > will copy the private copy of the file into its original location and > release the lock - or user will cancel the checkout (removing the > copy and releasing the lock) > > I see that exist-db has support for read and exclusive locks (inside > the util: module). > > Can they be used to implement such a scenario? > > Is it possible to associate (arbitrary metadata) with locks like lock > time, user who created the lock, app specific data? > > Is it possible to introspect all current locks on the database? > > Is there something like a lock token (in WebDAV) does one needs to > release a lock? > > Andreas

> oops, this was intended for the exist-db guys...but the question > are similar...anyone used BaseX with a checkout-checkin scenario?

Christian Grün wrote: >> oops, this was intended for the exist-db guys...but the question >> are similar...anyone used BaseX with a checkout-checkin scenario? > > First of all: I'm also interested to hear more about this from our > users.. > > Talking about locking functions, we plan to generalize our WebDAV > locking feature to a general database locking mechanism. The WebDAV > locks already contain information on the user who created the lock, > a timeout, the scope (shared vs. exclusive), the lock id, etc., and > this info could be extended by the lock time and other (maybe even > application specific) info. Do you have some examples for data that > could be specific to an application?

On Mon, Feb 23, 2015 at 6:28 PM, <zopyxfilter at gmail.com> wrote: > Andreas Jung wrote: >> Christian Grün wrote: >>>> oops, this was intended for the exist-db guys...but the question >>>> are similar...anyone used BaseX with a checkout-checkin scenario? >>> First of all: I'm also interested to hear more about this from our >>> users.. >> >>> Talking about locking functions, we plan to generalize our WebDAV >>> locking feature to a general database locking mechanism. The WebDAV >>> locks already contain information on the user who created the lock, >>> a timeout, the scope (shared vs. exclusive), the lock id, etc., and >>> this info could be extended by the lock time and other (maybe even >>> application specific) info. Do you have some examples for data that >>> could be specific to an application? >> >> In our SGML CMS you were able to checkout parts of a bigger document >> for example a chapter. In this case we needed additional information >> inside the checked-out document - perhaps not on the lock itself - >> we used processing instructions for that as far as I recall. >> >> Being able to store arbitrary key-value pairs on a lock would be >> sufficient. Otherweise I would store such application specific >> data as an additional XML file containing these informations. > > At least needs to be some support for lock token in order detect > lock/unlock conflicts. > > Andreas

Christian Grün wrote: > I have added a GitHub issue on your locking request [1]. In the > meanwhile, it's probably best to use RESTXQ (XQuery) and check if a > resource is locked before returning it to a user. > > [1] https://github.com/BaseXdb/basex/issues/1083