June 2000 - Zope-Dev

Re: [Zope-dev] Externalize or Adapt? (ZPatterns)
by Phillip J. Eby 10 Jun '00

10 Jun '00

At 05:46 PM 6/9/00 +0800, Mike wrote: >Great! Excellent! >Thank you Phillip for a good explanation. >I guess should write something like for the ZPatterns Wiki. Ty added it yesterday, and I've linked to it as DropZoneExample from various points in the Wiki. > >One more thing we still need is a set of 'right hand' rules. >Let me try to formalize ZPatterns-based design process. > >1. Write scenario (client comes to skydiving office blah blah blah...) >2. Detect roles learning scenario (Orders, Planes, Students etc) >3. Create an empty (blackbox) Specialist for each role >4. Populate the specialists with methods implementing roles >5. Create (whitebox) specialists implementing scenario > >Thus, the object classes (Customer, Order) went nowhere. The things >ruled by black specialists are just identity markers, without methods, >types and names. Not quite. There are three problem domains here: two reused horizontal domains (accounting and resource scheduling) and one vertical domain (skydiving facility). The two horizontal domains contain blackbox Specialists such as Invoices and Reservations. You don't modify the black boxes, because that's what you're reusing. The horizontal domains also contain whiteboxes: Customer, Resource, ResourceUser, etc. These just contain the data handling needed to adapt a "Party" or other basic object to be usable as a Customer or ResourceUser. These whiteboxes are your hook point to interface the framework to a larger application. You just tell it where "Party" objects are. >Or is the object an specialist specific internal abstraction which never >leaves specialist's frames and have methods and type just for >specialist's fun? Not quite. See below. >"Phillip J. Eby" wrote: >> First, I'm going to create some ZClasses, and specialists to go with them: >> SkyDiver, Pilot, Airplane, FlightManifest, RentalTicket, RentalItem >> (w/subclass for Parachute, Helmet, and certain other specific items). Then >> I'm going to set up the Resources and Products specialists to access my own >> specialists for these ZClasses. (Notice that I am going in and directly > >How you will set up those specialists? By adding >get(Resources|Products)Specialist methods? I will add a "retrieveItem" method to the Specialist which, instead of accessing a rack in the local specialist (the default implementation), it will instead call (for example) SkyDivers.getItem(). Thus, when you call Customers.getItem(), you will actually get an object from the SkyDivers specialist. In other words, I make the horizontal domain specialist delegate to the vertical specialist. >> that a Party plays in a resource scheduling system. SkyDiver, then should >> implement a Party interface, allowing it to be *used as* a Customer or >> ResourceUser. Thus, SkyDiver can be used by *any* framework that needs to >> collaborate with a Party object, although it may have a new *role* in which >> the party will be used. For example, if I later add a curriculum >> management system to cover my skydiver training courses, I will want >> SkyDiver to fill the Student role. > >Well, we have two specialists, implementing roles (again, who _actually_ >implements the role, specialist or class, CustomerSpecialist or >Customer?). The SkyDiver implements its own behavior. The Customers specialist implements anything relating to customers as a group, or to creating a new customer. To do this, it may have to ask the SkyDivers specialist to do things on its behalf. For example, if the billing system lets you add customers, it will end up actually asking the SkyDivers specialist to add a SkyDiver, and will use the SkyDivers specialist's forms to get the necessary information to create one. >Now, "SkyDiver ... *used as*" means we should: > > 1. subclass (not a good choice) > 2. implement interface > 2.1. by copying and pasting methods code (or whole methoids) > 2.2. by proxiyng (SkyDiver has a references to actual Customer > and ResourceUser) > 2.3. by transmitting messages to SkyDiverSpecialist which will pass > unhandled messages to CustomerSpecialist and > ResourceUserSpecialist (this is a variant of 2.2. case) > >The 2.3. case means we should use objects without types (identity >markers). None of the above. SkyDiver should inherit from a Party base class. For Customer and ResourceUser behavior, one adds propertysheets whose class is provided by the respective frameworks. This is extension through *composition*, rather than inheritance. It is similar to the COM approach, where you can ask an object to give you a pointer to an interface. In this approach, you ask for a propertysheet that provides the interface. >> I will also make some changes to each of these specialists to replace >> certain common UI snippets to be relevant to the kinds of things I'm >> dealing with. For example, in the Customers and ResourceUsers Specialists, >> I will replace the findForm method (if that's what it's called) to be a >> call to SkyDivers.findForm - a form that searches for skydivers by their >> ratings, certification, or freefall style, as well as name or phone number. > >How about Editor and Renderer plug-ins for each specialist? I think that they are not necessarily a good idea. I don't really see a value-add over just having a DTML (or other) method. The requesting Specialist just wants a page snippet, with at most some parameters indicating what field name it would like the selected object to have. Now, it may make sense at some point to make (generally useful) Form objects which can return such snippets. I haven't had a chance to look at ZFormulator or MetaPublisher, which I understand may both have some applicable solutions in the form rendering area. >> lifting" machinery and plug it into their local specialists, then gut the >> collaborator specialist and wire it to the appropriate local specialist. > >If I understand something at all, whitebox specialist (Script?) called >SkyDiverSpecialist must have its own data source (rack) for SkyDiver >class and use 2.2. strategy mentioned above. (I just see no other way). Very close. It's just done more simply, and doesn't need the co-operation of the SkyDiver class. The SkyDivers specialist simply provides them as propertysheets. In this way, you can "adapt" between frameworks as long as you always use propertysheets as whitebox "decorators". So, if you have a document management system (knows about authors, revisions, etc.), and a project management system (knows about assigments, deadlines), you can make them work together if the project management system stores assignment/deadline stuff in a project management-specific sheet. And with ZPatterns, it's easy to add support for that sheet to existing objects - without altering existing code. Just plug the sheet providers into the appropriate specialists, and then extend the project management system's Tasks specialist to be able to delegate to your Documents specialist, as well as any others it needs to talk to. Granted, some integrations like this may be complex, especially once you start factoring indexes and searches and integrity rules. However, they are at least *possible* with ZPatterns, and the results should be worth the work. One of the very first inspirations for ZPatterns was a mailing-list discussion about event scheduling in Zope. It made me realize that there wasn't a good way to mingle horizontal and vertical frameworks in Zope. i.e., you couldn't easily go back in and add event scheduling or project management to a bunch of classes that you got from somebody else, or even your own classes, without changing your base classes or other really nasty things (like copying code). So, when used as framework glue, ZPatterns emphasises run-time composition rather than code-time inheritance. Of course, ZPatterns can be used as just an application-building framework on its own, but if used wisely, your applications should then be reusable as frameworks by others.

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[TRACE] Unable to mount mountable storage
by Bill Anderson 10 Jun '00

10 Jun '00

OK, thought I would start playing with this... Figured I would load a separate site to start with . It fails, claiming it cant load oid. The site is orignally on 2.1.6, if it matters. Then I copied the current Data,fs to foo.fs, and figured I'd give it a try, being a new .fs and all. It complains about duplicate ids. What am I missing? I can copy Data.fs.in to a new name, and mount it fine. OID TRACEBACK: ========================== Traceback (innermost last): File /home/ucntcme/ZopeTest/lib/python/ZPublisher/Publish.py, line 222, in publish_module File /home/ucntcme/ZopeTest/lib/python/ZPublisher/Publish.py, line 187, in publish File /home/ucntcme/ZopeTest/lib/python/Zope/__init__.py, line 221, in zpublisher_exception_hook File /home/ucntcme/ZopeTest/lib/python/ZPublisher/Publish.py, line 171, in publish File /home/ucntcme/ZopeTest/lib/python/ZPublisher/mapply.py, line 160, in mapply (Object: manage_addMountedFileStorage) File /home/ucntcme/ZopeTest/lib/python/ZPublisher/Publish.py, line 112, in call_object (Object: manage_addMountedFileStorage) File /home/ucntcme/ZopeTest/lib/python/Products/MountedFileStorage/MountedFileStorage.py, line 24, in manage_addMountedFileStorage File /home/ucntcme/ZopeTest/lib/python/OFS/ObjectManager.py, line 260, in _setObject (Object: ApplicationDefaultPermissions) File /home/ucntcme/ZopeTest/lib/python/OFS/ObjectManager.py, line 267, in manage_afterAdd (Object: ApplicationDefaultPermissions) File /home/ucntcme/ZopeTest/lib/python/OFS/ObjectManager.py, line 267, in manage_afterAdd (Object: ElementWithAttributes) File /home/ucntcme/ZopeTest/lib/python/OFS/ObjectManager.py, line 267, in manage_afterAdd (Object: ElementWithAttributes) File /home/ucntcme/ZopeTest/lib/python/OFS/ObjectManager.py, line 267, in manage_afterAdd (Object: ElementWithAttributes) File /home/ucntcme/ZopeTest/lib/python/ZClasses/ZClass.py, line 417, in manage_afterAdd (Object: ManagedMeeting) File /home/ucntcme/ZopeTest/lib/python/ZClasses/ZClass.py, line 370, in _register (Object: ManagedMeeting) File /home/ucntcme/ZopeTest/lib/python/ZODB/Connection.py, line 441, in setstate File /home/ucntcme/ZopeTest/lib/python/ZODB/Connection.py, line 213, in _persistent_load (Info: onClass\012ExtensionClass\012q\001(U\006LMUserq\002(cZClasses.ZClass\012PersistentClass\012q\003cProducts.LoginManager.UserSources\012LoginUser\012q\004cOFS.SimpleItem\012SimpleItem\012q\005tq\006}q\007(U\004iconq\010U\000U\012_p_changedq\011K\001U\007__doc__q\012U\007LM Userq\013U\006_p_oidq\014U\010\000\000\000\000\000\000\004rq\015U\011meta_typeq\016U\007LM Userq\017U\005Fnameq\020U\000U\016propertysheetsq\021U\010\000\000\000\000\000\000\004wq\022QU\005Lnameq\023U\000U\016manage_optionsq\024)U\006passwdq\025U\000U\022__ac_permissions__q\026)U\011_p_serialq\027U\010\0034\353#\315f\322\346q\030U\012__module__q\031U\031*ykluV9yvI34UID2R6HV/dQ==q\032utq\033t.N.')) Could not load oid

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DirectoryStorage 0.04
by Petru Paler 09 Jun '00

09 Jun '00

Changelog: 0.04: - added missing binary flags to open() calls to make it work on NT. - added flush() calls after file writing - added close() method to the DirectoryStorage class 0.03: - don't die if posix.fsync is not available - base class renamed to DirectoryStorage - added directory (re)creation and locking - added a 'magic' file - last oid file open/close bug - moved serials to an gdbm database 0.02: - converted to using os.path.join 0.01: - initial release -Petru

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Alternative Storages: (was RelationalStorage (was LocalFS))
by Jimmie Houchin 09 Jun '00

09 Jun '00

This was on the Zope list and I've move this to Zope-dev as I feel it is more appropriate. I have been making notes to myself for awhile with ideas about things I would like to explore with Zope Storages when I am able. I have not posted any of them since talk is cheap. But I guess since I'm full of cheap talk I'll let it go. :) I'll also post this to the ZODB zwiki after I see what's left standing after analysis. :) As far as usage is concerned I generally like the ZODB best because it is reasonably transparent to the building of a web app with Zope. However there are areas in which it does not currently excel that which if your site requires these skills then alternatives must be used. A couple of areas are data size and heavy writes. Some people use an RDBMS to solve these issues. While this will work it does expect more from the developer. Some do not have the skills or the tools. Even if one does it still requires leaving the transparency of developing with the ZODB. Multiple file storage for the ZODB has been proposed as a solution and there are 2 proposals currently on the ZODB ZWiki. I will add another. Class/Object based db files. Each class gets it's own db file. This could be similar to the current ZODB file except specific to a class. As objects are created they are appended to the db file for their class. This could be somewhat analogous to tables in an RDBMS. Advantages would be spreading out the data space over multiple files which would help with some oses. Also I think that each class has different characteristics which would be able to be managed better if separate. Example: AutoParts You have an AutoParts class. The objects will change very little once created. However there are a lot of objects and news added periodically. This file will need packed seldom. It will also be simple to backup and not need backed up often as changes are periodic and regular. RetailStore In a retail store the product objects are very volatile. Vendors can change. Prices do change. A productObject file would have different usage characteristics than the AutoParts object. Some classes are perfect for few writes and many reads. Others less so. Earlier Andrew Kuchling was wanting to walk the object tree. This would provide a relatively easy way to walk the object tree. This could be implemented with some support classes which have to be inherited from to create a class.db file. Any class not so doing would go into the standard ZODB. This could help provide desired management features for the characteristics of each. It would be nice if in the management you could set the path to the file. This would allow for multiple disks or partitions for data storage. This too would help with backups and such. Just a few ideas. They may not stand up to examination, but that's okay. I just thought I would put them on the table. Jimmie Houchin Chris McDonough wrote: > > All, > > I've put some stuff about a proposed RelationalStorage in the ZODB wiki > at http://www.zope.org/Members/jim/ZODB > > Its goal is to allow you to use a SQL database as a Storage, which > somewhat coincidentally would also get around the single-file 2GB > limitation. > > I would appreciate comments (in the wiki or here). The table structure > I'm not sure on, it's only a skeleton right now... > > Jason Spisak wrote: > > > > Jonothan: > > > > > Shouldn't be too difficult. (I know, famous last words.) I'd be interested in > > > banging out a prototype. > > > > I looked at FileStorage and the BasicStorage yesterday. I am trying to get > > a feel for it. > > > > > I'll have to see when I can get to it after responding > > > to all these emails about LocalFS that piled up while I was on vacation. > > > > > > > That's because it's an amazing product. > > > > All my best, > > > > Jason Spisak > > CIO > > HireTechs.com > > 6151 West Century Boulevard > > Suite 900 > > Los Angeles, CA 90045 > > P. 310.665.3444 > > F. 310.665.3544 > > > > Under US Code Title 47, Sec.227(b)(1)(C), Sec.227(a)(2)(B) This email > > address may not be added to any commercial mail list with out my > > permission. Violation of my privacy with advertising or SPAM will > > result in a suit for a MINIMUM of $500 damages/incident, $1500 for > > repeats. > > > > _______________________________________________ > > Zope maillist - Zope(a)zope.org > > http://lists.zope.org/mailman/listinfo/zope > > ** No cross posts or HTML encoding! ** > > (Related lists - > > http://lists.zope.org/mailman/listinfo/zope-announce > > http://lists.zope.org/mailman/listinfo/zope-dev ) > > -- > Chris McDonough > Digital Creations > Publishers of Zope - http://www.zope.org > > _______________________________________________ > Zope maillist - Zope(a)zope.org > http://lists.zope.org/mailman/listinfo/zope > ** No cross posts or HTML encoding! ** > (Related lists - > http://lists.zope.org/mailman/listinfo/zope-announce > http://lists.zope.org/mailman/listinfo/zope-dev )

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[Ann] Zope 2.1.6 ZCatalog patches: "and not", "near"
by Dieter Maurer 09 Jun '00

09 Jun '00

Zope 2.1.6's ZCatalog contains a small bug in its handling of "and not" searches. URL:http://www.handshake.de/~dieter/pyprojects/zope/andnot.pat fixes this bug. "near" searches do not work. As Michel pointed out, the relevant indexes have been removed for space considerations. The patch at URL:http://www.handshake.de/~dieter/pyprojects/zope/near.pat enables "near" searches. Instead of saving a word position index, word positions are determined dynamically during near searches (by reading the relevant document part). Of cause, this is much slower than an index based search. Moreover, it works only for persistent objects. It does not work e.g. for LocalFS objects (for them "near" is equivalent to "and"). For these reasons, you may not want to apply this patch. The score function for near searches is currently very ad hoc and should probably replaces by a more sensible function. Dieter

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Re: Packaging ZODB, ZEO...
by Andrew M. Kuchling 09 Jun '00

09 Jun '00

I've heard nothing about my offer to package ZODB separately, and today's the day I copy stuff onto a laptop for the trip. Some direction here would be nice; there's lots of other stuff I can hack on if I don't get a response... --amk

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Re: [Zope-dev] Externalize or Adapt? (ZPatterns)
by Tres Seaver 09 Jun '00

09 Jun '00

"Phillip J. Eby" <pje(a)telecommunity.com> wrote: <snip terrific post motivating ZPatterns> Wow, Phillip! That was the best 'grounding' I have seen yet for ZPatterns; in fact, I think it was exactly what I needed to let me wrap my head around them. Thanks very much for posting this! Tres. -- =========================================================== Tres Seaver tseaver(a)digicool.com Digital Creations "Zope Dealers" http://www.zope.org

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assigning proxy roles from python product, take 2
by R. David Murray 09 Jun '00

09 Jun '00

Hmm. No takers the first time. Quick review: python product, product instantiates a DTML method and tries to assign it a proxy role. Proxy role gets assigned, but a 'manager' account can no longer access the method, though superuser can. Zope 2.1.6. I played with the product some more, moving some stuff around, and this time when I instantiated it, the proxy role no longer seems to be working (I get a login box when I try to dereference the method). The manager/superuser behavior is the same. The folder is created using newWampumboxF = Folder(). Then a method named processCCTrans is added to this folder using a manage_addDocument call. That obviously works fine. I then try to add the proxy role by doing the following: x=newWampumboxF.processCCTrans x._proxy_roles=('Manager',) newWampumboxF.processCCTrans=x It seems to me from my reading of the code that this should be equivalent to what manage_proxy does, though obviously without the through-the-web security checks. But the end result is a DTML method that I can only view as superuser, but that has Manager checked in its 'proxy' management screen (as well as a perfectly normal appearing security page). Any guesses? Any suggestions for experiements to run, even? --RDM

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Re: [Zope-dev] assigning proxy roles from python product, take 2
by Rik Hoekstra 09 Jun '00

09 Jun '00

>Hmm. No takers the first time. > >Quick review: python product, product instantiates a DTML method >and tries to assign it a proxy role. Proxy role gets assigned, >but a 'manager' account can no longer access the method, though >superuser can. Zope 2.1.6. > >I played with the product some more, moving some stuff around, and >this time when I instantiated it, the proxy role no longer seems >to be working (I get a login box when I try to dereference the >method). The manager/superuser behavior is the same. > >The folder is created using newWampumboxF = Folder(). Then a >method named processCCTrans is added to this folder using a >manage_addDocument call. That obviously works fine. I then try >to add the proxy role by doing the following: > >x=newWampumboxF.processCCTrans >x._proxy_roles=('Manager',) >newWampumboxF.processCCTrans=x > >It seems to me from my reading of the code that this should be >equivalent to what manage_proxy does, though obviously >without the through-the-web security checks. But the end >result is a DTML method that I can only view as superuser, >but that has Manager checked in its 'proxy' management screen >(as well as a perfectly normal appearing security page). > >Any guesses? Any suggestions for experiements to run, even? I reported this a looooong time ago (in the Collector, don't have a number) as a bug for normal proxy roles (not product related), but never got an answer. So probably this is hard solve (or no one saw it). This won't help, I know, but thought I'd just let you know. Rik

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Externalize or Adapt? (ZPatterns)
by Mike 09 Jun '00

09 Jun '00

Hi, suppose I have two Specialists (A and B) written independently each other. I need to use certain set of services provided by one Specialist (A) in other (B). I see two way: 1) Create common proxy for A, implementing public subset of A's interface and make B (and other possible clients) depending on that externalized interface. Problem: high dependency on A's external interface 2) Write specialized (A->B) pluggable adapters each time I need to use A's services in clients. Problem: M*N What do you think is ... hmmm... less painful way? Thanks, Mike

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