Zope Product Development With CMF/Plone. Reid Linnemann Oklahoma Department of Career and Technology Education

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1 Zope Product Development With CMF/Plone Reid Linnemann Oklahoma Department of Career and Technology Education

2 What is Zope? What is Zope? Zope is an application server, not a web server Zpublisher is Zope's web publishing component, handling HTTP "Publishes" requested python objects that are stored in a persistent python object database called ZODB, e.g.: Folder Page Template Plone Site Image My Crazy Type I Made Today

3 What is Zope? Zope Architecture ZServer Web Server apache frontend Relational Database MySQL Products ZMySQLDA Plone SQLUserManager etc.

4 What is Zope? How does publishing work? Zope receives an request The request is forwarded to ZPublisher ZPublisher traverses to find the object in the url proto://host:port/path?query ZPublisher calls a method on the object ( call, getitem, etc.), using parsed query for arguments a response is sent back to the browser Requirements for an object/method to be published: The object/method must have a docstring The name of the object/method must not begin with an underscore "_" The object cannot be a python module

5 What is Zope? What about security? During traversal, the ZPublisher makes security checks for each object it touches, to ensure the user is authorized Arguments are converted from the query arg[:type modifier...]=value ZPublisher marshals arguments from the query, the default argument type is str Many types str,text,lines,tokens int, long, float boolean date list,tuple Some type attributes required, ignore_empty, default

6 What is Zope? Records are supported through special notation var.attr:int:record, e.g. ZPublisher amalgamates list, tuple, default and not_empty query string arguments into sensible arguments for the method call, so a series of 'countries:list=x' arguments in the query string become one list named 'countries' that is passed to the method. Publishing is transactional When Zope gets a request, it starts a transaction If an unhandled exception is raised, the transaction is aborted all changes in progress to the ZODB for that request are aborted in ZMySQLDB, transactions are honored for database engines that support them; InnoDB does this but not MyISAM

7 What is Zope? XMLRPC All Zope published objects support XMLRPC You can use xmlrpclib to utilize Zope objects, e.g.: app = xmlrpclib.server(' app.getfoo() Messages can only consist of base python types, so getfoo() can return and int or a float, but not a ZSQLMethod CMF CMF is the Content Management Framework Set of services and content objects for building content-oriented dynamic portals Membership, Workflow, Content, Discussion, Syndication, etc.

8 Zope Products Products are python packages that extend the capabilities of Zope Define new object classes, DTML tags, etc. that can be used in Zope A class can define a more complex object that can't be feasibly represented as a collection of scripts, templates, and SQL methods for example, 'Student' Classes can be instantiated in Zope to create objects that abstract and encapsulate their complex attributes and behaviors

9 Zope Products What does a Product look like? A Product is a folder that contains: init.py contains an initialize() function that accepts one parameter, context uses Zope framework to add functionality to Zope, e.g. context.registerclass() to make an object class available in Zope's Add dropdown README.txt (optional) version.txt help directory (optional) python sources to define classes, libraries supporting media (images, template sources, sql queries)

10 Zope Products Classes Zope object classes usually derive from one or more OFS base classes OFS.SimpleItem OFS.ObjectManager OFS.PropertyManager Can also derive from more complex classes CMFCore.PortalFolder CMFCalendar.Event

11 Zope Products Class Contents init () method The class constructor A factory method, e.g. manage_addmyclass Responsible for creating an instance of the class of a requested id, and adding it to the given context manage_options a structure to define ZMI tabs for an instance of the class when viewed in the ZMI tuple of dictionaries, keyed on: label label on the management tab action url called when the tab is selected target (optional) frame to display the action in help (optional) help information, details are in the developer's guide

12 Zope Products A security object for issuing Zope security declarations This is stripped from the class when Zope initializes it during an InitializeClass() call when the product is refreshed or Zope is started The InitializeClass() call should be the last statement in your class definition file, in global scope, e.g. from OFS.SimpleItem import SimpleItem class myclass(simpleitem):... InitializeClass(myClass)

13 Zope Five Five is Zope 3 functionality in Zope = 5, get it? Those Zope Labs guys are so clever.. Use Five in favor of deprecated Zope 2 API wherever possible manage_afteradd, manage_beforedelete, etc. should be replaced with Event subscribers Zope 2 interfaces from the Interface package should be avoided in favor of Zope 3 interfaces in zope.interface

14 Plone Plone We use it for its mature framework Built on CMF, which is in turn built on Zope skins globally acquirable objects that are customizable by site administrators content-types that can be added by members tool singletons action providers form controllers catalogs membership etc.

15 Plone TTW Application Development Several drawbacks disorganized unmanageable with VCS, not portable between instances high overhead in execution due to amount of context traversals low security, low authorization awareness restricted code forces dependence on external methods can't automate tests basically, just not a suitable for our needs

16 Plone How we should write software for Plone: Filesystem Products Not much, if any, of our applications should be content objects in Plone. We don't use the ZODB for storage of application data! e.g. TIP Agreements are not content objects in the ZODB. We make web requests to edit an agreement - not identified by a path in the ZODB, but by a query string on a broker object. The only objects that really need to be in the ZODB are skins for customized Plone look and feel (with FSDirectoryViews) skins for UI portlets, graphics, etc (FSDirectoryViews) tool singletons to act as object brokers for RDB data, provide well-defined actions for web interfaces user/groups source relational database hook(s)

17 Plone Advantages We get to use the Zope security framework for authorization Much fewer context calls and publisher traversals, usually only on the point of entry from the web interface business logic is 100% python with library level access no longer limited by restricted python code code is organized, maintainable methods and members that should not be seen directly TTW can be hidden from the publisher Can still utilize complex Zope types in product code A Zope object is still a python object Create a Zope object (ZSQLMethod, PageTemplate, etc.) in your class, and assign it to a member!

18 Plone Tool Classes Inherit from CMFCore.utils.UniqueObject Predetermined id for an instanced object Cannot change instanced object's id id cannot be used lower in the acquisition chain, so object cannot be overridden Inherit from CMFCore.ActionProviderBase. ActionProviderBase The tool will have several methods declared that make up the API, and methods or obejcts to provide the web interface ActionProvider Actions describe web interface actions

19 Plone descriptive name url of the form/entry point required permission to see the action organizational category visibility flag (lets the action by globally enabled/disabled) Why do we want ActionProvider Actions? Zope lets you define an actions structure already, but that is only useful for the ZMI. Members don't necessarily have access to the ZMI, and Plone doesn't use it anyway You may think, "why bother? I can just put the url in a page template!" Not dynamic, unless you write a lot of extra tal logic (bad) Making changes to an action url that occurs in several page templates requires far more care and work

20 Plone Actions in an ActionProviders can be queried through a CMF/Plone ActionsTool object (portal_actions) By querying, we can write generic code that is suitable for all actions Changes to action definitions are reflected in the generic code without altering it We can also register action icons for our actions with the ActionIcons tool (portal_actionicons). Again, this lets a generic snippet of code function for an entire range of available actions Action Essentials ActionProviderBase.addAction() adds an action to the provider's action list call this in your class's init () method to set up default actions for your tools

21 Plone Can be called at runtime to add more actions It's a dual-purposed ZMI method! pass no request to it if not using it interactively with a user ActionProverderBase.getActionInfo() action_chain parameter is a sequence of strings with form 'category/id' ActionsTool.listFilteredActions() hands back a dictionary keyed on category ids, values are lists of action infos actions are ordered in the providers! Tool classes are not registered in init.py as are other classes use CMFCore.utils.ToolInit CMFCore.utils.ToolInit(...).initialize(context)

22 Plone QuickInstaller CMF facility for activating/deactivating products inside a CMF Site Commonly referred to as 'installing' and 'deinstalling', which adds confusion What does that mean? skins CMF content-types Register portal actions Object instances in the portal root (tools, e.g.) Requirements Subpackage 'Extensions' Install.py module in 'Extensions' with functions install(self) and uninstall(self) (external methods)

23 Unit Tests Unit Tests Zope has a unit test framework built on PyUnit Based on JUnit To use it, your Product should have a subpackage named 'tests' tests subpackage contains any number of modules each module defines test case classes that derive from unittest.testcase following class definitions, the modules should define a function test_suite() that returns a test suite, e.g. from unittest.makesuite()

24 Unit Tests You can run tests on your product with zopectl, e.g. zopectl test -s CMFCore there are many options to zopectl test, use the help flag to learn more How do I write unit tests? Identify a feature that should be tested use case/specification bug fix interface contract Determine a simple routine to demonstrate the feature e.g. create an instance of an object and call a method on it use assert() to verify the result, e.g. assert(o.getfoo == 'foo') failed assertions will indicate the test failed

25 Unit Tests Why bother? Well written unit tests verify that the software adheres to the specifications Unit tests for bug fixes verify that later changes do not create regressions

26 References Zope Plone Testing and debuging

Top 20 Plone Pitfalls

Top 20 Plone Pitfalls And Then Some www.plonesolutions.com Stefan H. Holek stefan@plonesolutions.com All disclaimers apply. I am not going to argue over any of these, don t try. 1 Do not put off learning