May 2003 - Zope-Dev - Zope lists

Several reports about data loss after packing
by Maik Jablonski 12 May '03

12 May '03

Hi, in the last weeks there were several reports (recently two reports on zope(a)zope.org) about data loss after packing the ZODB. I've encountered the problem two times in production environments for myself... and I'm not lucky about that fact. See: http://www.dzug.org/mailinglisten/zope-org-zope/archive/2003/2003-05/105250… http://www.dzug.org/mailinglisten/zope-org-zope/archive/2003/2003-05/105273… For me all the descriptions seem to be related to: http://collector.zope.org/Zope/875 Maybe it's only a problem when ZEO is used (I'm not sure about this). I don't have any idea how to fix this issue, but I think this one should be fixed as soon as possible. Cheers, Maik

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Re: [Zope-dev] PROPOSAL: ZODB Relationships
by Lennart Regebro 12 May '03

12 May '03

Sorry, put this in the wrong forum... -------- Original Message -------- Subject: [Zope] Re: [Zope-dev] PROPOSAL: ZODB Relationships From: Lennart Regebro <lennart(a)regebro.nu> Jean Jordaan wrote: > You could still delete the storage if you wanted to kill all stored > relations, couldn't you? Well, yes, which yet again makes me think this is not a good path forward. It feels to me that the relation either should be stored in the object, and indexed somewhere, or there should be one central secret invisible storage. The relationship between two objects should not be deletable from "outside" the object, that seems really weird. If the relationship really is stored outside the object, then the only way to delete that relationship should be through an API. (With reasonable exceptions, such as deleting the ZODB, and setting Application.__relations = None, or something like that).

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Bobo-Exception-.. can produce rfc non compliant headers in response.
by Romain Slootmaekers 11 May '03

11 May '03

Yo, in case of an exception, the following headers, can produce non compliant HTTP response headers. Bobo-Exception-File Bobo-Exception-Type Bobo-Exception-Value Especially the Bobo-Exception-Value header, which is a chopped off version of the body of the response, is a cause of problems. fe -------------- included example ----------------- Bobo-Exception-Value: <?xml version="1.0"?> <!DOCTYPE wml PUBLIC "-//WAPFORUM//DTD WML 1.1//EN" "http://www.wapforum.org/DTD/wml_1.1.xml"> <wml> <card> <p -------------- /included example ---------------- Normally, your browser doesn't barf on this, but browsers on small devices (like mobile phones) and their gateways are way more picky :( I have more than one problem with these headers: 1) most important: unpredictability of the RFC compliance. not a good thing. 2) security related: they give out way to much information to be confortable with. a client doesn't have any business with the absolute path to your zope install (Bobo-exception-File) and you even get these even when not running with the -D option. Although not enough info to hack/crack/whatever the machine/server it gives a hacker something concrete to work with. 3) usefulness: what do you gain from having these headers anyway? you have the error log on server side that contains the same information in another form. Is there still anybody out there who uses this ? if not, it's better to throw the whole thing out of the codebase, no ? Romain.

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Great opportunity
by senserospj＠freg.com 10 May '03

10 May '03

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PROPOSAL: ZODB Relationships
by roche＠upfrontsystems.co.za 09 May '03

09 May '03

We finally have a proposal out for ZODB relationships. This proposal presents an API for relationships, summarises ideas and contributions from a lot of people and was fuelled by the recent discussions about relationships on Zope3-dev and Zope-dev. http://www.zope.org/Members/upfront/ZODBRelationships Your comments would be appreciated. Shane, thanks for all your help! -- Roché Compaan Upfront Systems http://www.upfrontsystems.co.za

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RE: [Zope-dev] RFC: RelationAware class for relations between obj ects
by sean.upton＠uniontrib.com 08 May '03

08 May '03

So the answer of what acts as a reference id for the referred-to object is: "Whatever the best id that your framework provides you is." If your framework is Zope3, a hubid is what you should use. In Zope2, a path or tuple containing (storagename, oid). In ZODB-sans-Zope, an oid (or a (storagename, oid) tuple with the storagename an empty string). I wonder if a single framework could adapt to fit the needs of all 3? It seems doable (different plugins to store the IDs, 'traverse' to the objects), I think... Sean -----Original Message----- From: Shane Hathaway [mailto:shane@zope.com] Sent: Thursday, May 08, 2003 12:15 PM To: sean.upton(a)uniontrib.com Cc: maxm(a)mxm.dk; zope-dev(a)zope.org Subject: Re: [Zope-dev] RFC: RelationAware class for relations between obj ects sean.upton(a)uniontrib.com wrote: > More in response to Shane than to Max M: I thought that one of the > continuing justification for ObjectHubs was that hubids were consistent > across multiple mounted storages, but oids were not? How could the > universal id problem be addressed at a lower level than Zope2 or Zope3 in > this case? When relationships are applied to Zope, they will always use hub IDs. Outside Zope, mounting and traversal don't always apply. > Then it starts to get amusing. One of the primary reasons for the > objecthub was to enable relations. So if the relations get implemented > in in ZODB but need some functionality, will it not end up as a > duplication of efforts? Don't assume there is actually any separate effort going on. The point of all of this talk is to discover in what ways the proposed relationship management is insufficient. Once understood, the ideas can come together. Shane

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RE: [Zope-dev] RFC: RelationAware class for relations between obj ects
by sean.upton＠uniontrib.com 08 May '03

08 May '03

More in response to Shane than to Max M: I thought that one of the continuing justification for ObjectHubs was that hubids were consistent across multiple mounted storages, but oids were not? How could the universal id problem be addressed at a lower level than Zope2 or Zope3 in this case? Sean -----Original Message----- From: Max M [mailto:maxm@mxm.dk] Sent: Thursday, May 08, 2003 10:47 AM To: Shane Hathaway Cc: zope-dev(a)zope.org Subject: Re: [Zope-dev] RFC: RelationAware class for relations between objects Shane Hathaway wrote: >> I was under the impression that the Objecthub is Zope specific. Is >> that so? Or is it a plain ZODB thing? > > It's Zope specific. But in plain ZODB, you can achieve pretty much > the same thing ObjectHub achieves using simple OIDs. So the > relationship code should allow, but not require, direct references > using OIDs. > > That might make you wonder why we need an object hub at all. The > difference between Zope and an average ZODB application is that Zope > lets you create a large multiuser system with many security contexts. > An object hub assists the process by restoring references in context > (i.e. with the correct context wrappers.) A simple ZODB application > generally has only one security context, so it doesn't need the extra > complexity. Then it starts to get amusing. One of the primary reasons for the objecthub was to enable relations. So if the relations get implemented in in ZODB but need some functionality, will it not end up as a duplication of efforts? regards max M _______________________________________________ Zope-Dev maillist - Zope-Dev(a)zope.org http://mail.zope.org/mailman/listinfo/zope-dev ** No cross posts or HTML encoding! ** (Related lists - http://mail.zope.org/mailman/listinfo/zope-announce http://mail.zope.org/mailman/listinfo/zope )

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RFC: RelationAware class for relations between objects
by roche＠upfrontsystems.co.za 08 May '03

08 May '03

There has been a lot of discussion about the need for a service that manages relations between objects on zope3-dev lately and in the past. I thought this would be a good time to share some code we have written to make relations a bit easier in Zope 2 and to invite some comments on it. The attached module provides a mixin class that collaborates with Max M's mxmRelations product almost like CatalogAwareness collaborates with the ZCatalog. I really hope that this can be an acceptable interim solution until relations are better managed by the ZODB or by some service in Zope 3. One area of contention is the overriding of __of__ to compute relations as attributes on objects. What kind of performance hit will this cause if one has a long chain of relations? I appreciate any comments. -- Roché Compaan Upfront Systems http://www.upfrontsystems.co.za

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mysql: broken abort hangs zope
by seb bacon 08 May '03

08 May '03

A client's site had been hanging under high loads. The problem appeared to be that the ZMySQLDA assumed transactions in the database even if the underlying tables were not transactional. I fixed it by changing the tables to be transactional. No more hangs. The abort was failing thus: 2003-05-08T13:32:59 ERROR(200) ZODB A storage error occured during transaction abort. This shouldn't happen. ...Transaction.py, line 392, in _commit_error AttributeError: Surrogate instance has no attribute '_p_oid' Under "normal" circumstances an aborted transaction against a non-transactional table produces a sensible error explaining what is going on. Here, somehow, the 'Surrogate' transaction had ended up with no attributes at all. 1) Where might those attributes have gone? 2) Why might this cause Zope to hang? Note I have only been able to reproduce the problem on the live server so far, and therefore I've not yet had an opportunity to debug in detail. seb -- [] j a m k i t seb bacon T: 020 7549 0520 F: 020 7490 1152 M: 07968 301 336 W: www.jamkit.com

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Getting object name in Standard_Error_Message
by Michael Best 08 May '03

08 May '03

Is there a variable one can call to get the object name that caused an error? 2.6.1 tracebacks don't appear to provide the object name. -Mike

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