On Wed, August 12, 2009 17:58, Jim Fulton wrote: > On Wed, Aug 12, 2009 at 10:33 AM, Jürgen > Herrmann<juergen.herrm...@xlhost.de> wrote: >> hi there! >> >> is there a zodb design document? > > There's: http://www.zope.org/Documentation/Developer/Models/ZODB > > But it is pretty old and out of date.
thanks, that was valueable information, especially the collab diagrams for transaction commit/abort. > >> what i'm interested in are the following things: >> - some basic description how the zodb works (f.ex. i don't understand >> what the difference between a serial and a transaction id is)? > > There is no difference. I thought there could be when I originally > designed ZODB, but it turns out to be good enough to use the tid as > the serial. thought so, but i wasn't sure enough :) > >> - looking at basestorage and the methods that have to be implemented, >> is there documentation what the reimplementation in a concrete >> subclass has to do exactly? (ordering of things, desired side effects >> etc.)? > > You should look at the storage interfaces in ZODB.interfaces and in > ZEO.interfaces. You should have a firm understanding of how > transactions work in general. Our transaction system is based on > time-stamps. > > You should also ask questions here. > >> why do i ask? i'd like to create a RadosStorage zodb backend ceph's >> underlying object storage "RADOS" (see >> http://ceph.newdream.net/blog/category/rados/ ) > > That's interesting. You might want to look at DirectoryStorage, > http://dirstorage.sourceforge.net/, which implements the storage APIs > (at least as they existed a few years ago) on top if a file system. > ok, looking at the interfaces and some more implementation code from FileStoreage, RelStorage, MappingStorage, MVCCMappingStorage etc. helped a lot. For now, one more questions though: i want RadosStorage to implement IMVCCStorage. so my understanding is that i remeber last_polled_tid (from invalidation polling and instead of loading the latest revision of an object, the storage always returns state as of the transaction with last_polled_tid, is that correct? if RadosStorage implements IMVCCStorage i guess i can skip the zeo interfaces, right? thanks for your help! jürgen -- >> XLhost.de - eXperts in Linux hosting ® << XLhost.de GmbH Jürgen Herrmann, Geschäftsführer Boelckestrasse 21, 93051 Regensburg, Germany Geschäftsführer: Volker Geith, Jürgen Herrmann Registriert unter: HRB9918 Umsatzsteuer-Identifikationsnummer: DE245931218 Fon: +49 (0)800 XLHOSTDE [0800 95467833] Fax: +49 (0)800 95467830 WEB: http://www.XLhost.de IRC: #xlh...@irc.quakenet.org _______________________________________________ For more information about ZODB, see the ZODB Wiki: http://www.zope.org/Wikis/ZODB/ ZODB-Dev mailing list - ZODB-Dev@zope.org http://mail.zope.org/mailman/listinfo/zodb-dev
