Plone Web Services2008 Plone ConferenceSally Kleinfeldt, Jazkarta

Background

• Plone’s current web services story is restricted to XMLRPC and RSS

• Becoming a glaring omission

• Plone Strategic Planning Summit voted it a focus area

• Support an official and complete web services API (REST)

Previous Work

• CIGNEX implemented SOAP web services on Archetypes for a customer

• z3c.rest provides a framework to build REST APIs on top of Zope 3

• Grok provides REST web services support

• Vice provides Atom syndication

• Boston and Naples sprints on RESTful WS

PSPS Project

• Ticket (includes link to plone-dev posts): http://dev.plone.org/plone/ticket/7842

• OpenPlans Page: http://www.openplans.org/projects/plone-web-services/project-home

Proposed Approaches

• Custom XML schemas for serializing content objects (building on GenericSetup)

• Microformats

• Atom Publishing Protocol possibly with GData extensions for search

• OpenSocial for Plone (JavaScript and Atom)

• Use OAuth for authentication

Recent News

• New “draft standard” announced Sept 10

• CMIS - Content Management Interoperability Services

• EMC, IBM, Microsoft, Alfresco, Open Text, Oracle, SAP, and others

• Draft specification for a web services standard for content management

CMIS

• Has SOAP and REST bindings

• REST binding defined as extension to Atom but tightly coupled to data model with “protocol extensions that tunnel the Web Services interface through fake-Atom and fake-HTTP” (Roy Fielding)

• Has hype, buzz and industry support (try a Google search and see EMC, Alfresco ads)

CMIS REST:Is It Any Good?

• Roy Fielding

• “I am getting tired of big companies making idiotic claims about REST and their so-called RESTful architectures. The only similarity between CMIS and REST is that they both have four-letter acronyms”

• http://roy.gbiv.com/untangled/2008/no-rest-in-cmis

CMIS REST:Is It Any Good?

• Roy Fielding con’t

• “...unless you expect blogging clients and syndication feeds to be the primary application of CMIS, it would make a lot more sense to define the representations in a microformat of HTML, JSON, YAML, or whatever else best fits the data...”

CMIS REST:Is It Any Good?

• Sam Ruby

• Cautiously optimistic

• Feels OASIS TC will address problems

• http://www.intertwingly.net/blog/2008/10/01/CMIS

Questions

• Should Plone adopt CMIS? or CMIS REST?

• No, reconsider when/if a “standard”

• Should Plone adopt microformats instead?

• Not systematically, just a view so easy to add for specific cases

• Should Plone adopt AtomPub?

• YES!

Technical Approach

• Existing Python AtomPub server packages include Amplee and FlatAtomPub

• Plone today isn't a good fit for REST style services because the Zope2 publisher ONLY does FTP, HTTP GET/POST ("browser web"), and WebDAV

AtomPub WSGI App?

• Idea: Atom Publishing application living in a Repoze ecosystem

• Aggregate content from several Plone, Grok, etc. sites

• Get around the lack of PUT/DELETE in Plone - act as a middleman

• Use zgeo.atom as starting point

Atom For Now

• Focus on providing read-only Atom representations

• Atom browser view that would apply to any folderish object

• Start at the root of the Plone site and discover all the Atom publishable objects by following the Atom links

Syndication vs. Web Services

• Syndication view: content owners would need to explicitly declare folders as feeds

• All-inclusive view: all content should provide the AtomPub interface

Conclusion

• Implementing RESTful web services will be a large and complex project, given the limitations of the Zope2 publisher

• Not realistic to expect it to get done in a sprint or even a series of sprints

• Most likely scenario: a customer needing support for CMIS (after all!)