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Feed the Masses
 

Feed the Masses

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This talk will introduce the audience to Vice http://www.openplans.org/projects/vice/project-home a cutting-edge solution to all outbound syndication needs for Plone 3.1+, providing RSS 1.0, RSS 2.0, ...

This talk will introduce the audience to Vice http://www.openplans.org/projects/vice/project-home a cutting-edge solution to all outbound syndication needs for Plone 3.1+, providing RSS 1.0, RSS 2.0, and Atom feed formats for all built in content types.

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    Feed the Masses Feed the Masses Presentation Transcript

    • Introducing Vice - Outbound Syndication in Plone via the Zope Component Architecture Paul Bugni Center for Public Health Informatics Feed the Masses T: 206.221.7444 F: 206.616.5249 1100 NE 45 th Street, Ste 405 Seattle, WA 98105 www.cphi.washington.edu
    • Agenda
      • Syndication
      • Vice History and Demonstration
      • Zope Component Architecture
      • Vice Integration
      • Customizing Syndication
    • What is syndication?
    • To publish or broadcast
      • Alternative to browser only audience for publishing content
    • “Web Feed” or “News Feed”
    • Data format for frequently updated content
    • Content distributors syndicate a web feed
    • Users can easily subscribe to the feed
    • Simplifies keeping up with changes
    • Using Aggregators
    •  
    •  
    • Prevailing syndication formats
      • That’s the beauty of standards, there are so many to pick from!
    • Two prevailing formats (as of mid-2005)
      • RSS 2.0
      • Atom 1.0
    • Exposing the myth of RSS compatibility
      • “I would like to publicly apologize for my previous misstatements. There are not 7 different and incompatible versions of RSS; there are 9” - Mark Pilgrim[1]
      • [1] http://diveintomark.org/archives/2004/02/04/incompatible-rss
    • RSS Stands For?
      • RDF (Resource Description Framework) Site Summary (RSS 1.0 and RSS 0.90)
      • Rich Site Summary (RSS 0.91)
      • Really Simple Syndication (RSS 2.0)
    • First, there was the mark up language RDF
      • Resource Description Framework
      • Used to store metadata (author, language, copyright…) about the content
    • RSS 0.90
      • In 1999 Netscape created the standard named RSS version 0.90
      • The beginning of RSS as we know it today
    • RSS 0.91 (part 1)
      • Dan Libby (Netscape) improved 0.90 and released RSS version 0.91
    • RSS 0.91 (part 2)
      • Dave Winer (Userland) also created an improvement of RSS 0.90 and called his version 0.91
    • Confusion ensued
      • Two versions named RSS 0.91 with different specifications
    • RSS 1.0
      • Rael Dornfest (O’Reily) released RSS version 1.0
      • Based on the RDF standard rather than RSS
      • RSS 1.0 was therefore incompatible with previous RSS versions
    • So to clear things up
      • Userland named their next release version 2.0
      • Harvard Law accepted responsibility for the RSS 2.0 specification
      • RSS 2.0 is very similar to 0.9 series (generally compatible)
      • RSS 1.0 remains very different
    • RSS 2.0
      • The specification is copyrighted by Harvard University and is frozen.
      • The intent is that future work will be done under a different name.
    • Atom 1.0
      • In part, motivated by the desire to be free of the RSS confusion
    • Atompub Working Group
    • IETF (Internet Engineering Task Force)
    • The Atom syndication format has been adopted as IETF Proposed Standard RFC 4287
    • RSS 2.0 versus Atom 1.0
      • A number of ambiguities exist in RSS 2.0 including:
        • No required fields (Atom requires title unique id and last updated)
        • No way to indicate if payload is encoded or plain text (Atom requires explicit declaration and includes options such as another XML vocabulary)
        • Autodiscover is not standardized and relies on an unregistered MIME type
        • Only Atom 1.0 is in an XML namespace and has specific guidelines for interpreting extension elements. (RSS 2.0 does not permit well formed XML markup)
      • http://www.intertwingly.net/wiki/pie/Rss20AndAtom10Compared
    • Need For Better Syndication in Plone
      • 2006-Feb-01 PLIP #128 was born
        • PLIP: Plone Improvement Proposal, analogous to python’s PEPs: Python Enhancement Proposal
      • #128: Pluggable Plone Syndication (PPS)
    • PLIP #128 Motivation
      • The current portal_syndication tool [only supports RSS 1.0 format and therefore] doesn’t have support for enclosures
    • PLIP #128 Motivation (continued)
      • [No current support to] extend syndication beyond common object attributes (i.e.Title, description, body etc.)
    • PLIP #128 Motivation (continued)
      • [No current support for] different types of feed entries for different content types (i.e. enclosures for media content a.k.a. podcasting)
    • PLIP #128
      • Enable advanced (RSS 2.0, Atom) site-wide syndication on all ATCT content “out-of-the-box” using Zope 3-based adaptors (via Five) which are extendable beyond ATCT to any content type.
      • (ATCT : ATContent Types)
    • Vice to the Rescue!
    • And the name ?
      • Before vice, there was “CMFSin”, “basesyndication”, “fatsyndication”, “synz”…
      • “ Vice was the cleanest name we could come up with.”
    • Vice was Born at the (now infamous) BBQ Sprint
      • Participants
        • Derek Richardson
        • Liz Dahlstrom
        • Mikel Larreategi
        • Jørgen Gårdsted Jørgensen
        • Paul Bugni
    • Then Vice Picked up a Sponsor
      • Derek Richardson (student)
      • Florian Schulze (mentor)
      • Report: http://www.openplans.org/projects/vice/google-summer-of-code-report
    • Vice also benefited from additional sprints
      • Plone4Artist Multimedia Sprint
      • 2007 Plone Conference Sprint
    • Installing Vice
    • Add Vice to the Buildout Eggs
      • Using buildout, edit buildout.cfg and add vice.plone.outbound to the [eggs] section:
      • eggs =
      • elementtree
      • vice.plone.outbound
    • Include the Vice Configuration Files (a la zcml slug)
      • Edit buildout.cfg and add vice.plone.outbound to the [instance] zcml
      • [instance]
      • zcml = vice.plone.outbound
    • That’s It?
      • Well, it should be, but Zope2 is not yet “eggified” and vice has dependencies related to Zope3 eggs
    • Workaround:
      • Add “fake_zope_eggs = true” to the [zope2] section of your buildout
    • Re-run ./bin/buildout
    • Install Product in Portal
      • Install “Outbound Syndication (Vice)”
    • Configure for Use
      • From the plone_control_panel (site setup)…
      • Find the syndication “configlet” listed in the add on product configuration
      • Enable syndication
    • Out of the box demo
      • < break to vice demo >
    • Design Goals
      • So which format do we architect around?
    • Ideally, none of them!
    • Separation of Concerns
      • Goal: separate the action of syndication from any particular format
    • Goal: Make it easy to add additional feed types
    • Goal: Make it easy to extend beyond common object attributes
    • How to Manage the Complexity?
      • Idea: isolate behavior in “objects” dedicated to a single purpose.
    • The Previous Approach:
      • Use multiple inheritance to mix and match objects (create mix-ins)
      • Subclass the mix-ins for further customizations
    • The Downsides
      • Complexity: objects built from a large number of base classes
      • Lack of cohesion: lots of unrelated attributes and methods
    • A Better Way
      • Introducing the Zope Component Architecture
    • Three Core Concepts
      • Interfaces
      • Components
      • Adapters
    • Interfaces
      • A formal description of how to interact with an object
      • Can be as simple as a label, or “marker”
    • Components
      • An “object” with introspective interfaces
    • Adapters
      • Inexpensive mechanism to add behavior (defined in interfaces) to existing components
      • Extends a components functionality without modifications to the component
    • Types of Components
      • Content Components
      • View Components
      • Adapter Components
      • Utility Components
    • Zope Component Architecture
      • Web Component Development with Zope 3, 3rd ed.
      • Philipp von Weitershausen
    • Core Vice Concepts
      • Containers (such as Folders) are “Feedable” (marked with the IFeedable interface, adaptable to the IFeed interface)
      • Content Objects (such as Documents) are “Feed Items” (adaptable to the IFeedItem interface)
    • IFeedable
      • Mark all folders as being “feedable”:
      • <class class=&quot;zope.app.folder.Folder&quot;>
      • <implements interface=&quot;.interfaces.IFeedable&quot; />
      • </class>
    • IFeed
      • Represents a “Feed”
      • Use to adapt objects that can provide items to feed
    • IFeed
      • class IFeed(Interface):
      • &quot;&quot;&quot;A syndication feed e.g. RSS, atom, etc. To syndicate a container,
      • adapt it to IFeed.
      • &quot;””
    • IFeed Adapters
      • Adapted to the Plone Site Root
      • All Folders (IATFolder)
    • IFeedItem
      • Represents a single item, or entry in a feed
    • IFeedItem
      • class IFeedItem(Interface):
      • &quot;&quot;&quot;A single syndication feed item.
      • &quot;&quot;”
    • IFeedItem Adapters
      • Adapted to the respective AT Content Types:
        • IATDocument
        • IATEvent
        • IATLink
        • IATImage
        • IATFile
        • IATNewsItem
    • Thus Vice Handles all AT Content Types “out of the box”
      • This includes any customized ATCT subclasses
    • How to Syndicate a New Type
    • New Type Must Be Adaptable to IFeedItem
    • Register the Adapter Factory
      • <!-- Vice demo, adapt example.dexterity.page.IPage to IFeedItem
      • so the example dexterity pages can be syndicated -->
      • <adapter
      • factory=&quot;.syndication.ExampleDexterityPageFeedItem&quot;
      • name=&quot;vice-default&quot;
      • trusted=&quot;true&quot; />
      • <class class=&quot;.syndication.ExampleDexterityPageFeedItem&quot;>
      • <require
      • permission=&quot;vice.ViewFeeds&quot;
      • interface=&quot;vice.outbound.interfaces.IFeedItem&quot; />
      • </class>
    • Define the IFeedItem Adapter Class
      • class ExampleDexterityPageFeedItem(ExampleDexterityFeedItemBase):
      • &quot;&quot;”Makes example.dexterity.page.IPage IFeedItem adaptable.
      • &quot;&quot;&quot;
      • implements(IFeedItem)
      • adapts(IPage, IFeed)
      • @property
      • def body(self):
      • &quot;&quot;&quot;See IFeedItem
      • &quot;&quot;&quot;
      • v = getMultiAdapter((self.context, self.context.REQUEST), Interface, name=u'syndicate_page')
      • return v().encode('utf-8')
    • Page Template for Body of Feed Item
      • <html xmlns=&quot;http://www.w3.org/1999/xhtml&quot; xml:lang=&quot;en&quot;
      • xmlns:tal=&quot;http://xml.zope.org/namespaces/tal&quot;
      • xmlns:metal=&quot;http://xml.zope.org/namespaces/metal&quot;
      • xmlns:i18n=&quot;http://xml.zope.org/namespaces/i18n&quot;
      • lang=&quot;en&quot;
      • i18n:domain=&quot;plone&quot;>
      • <body>
      • <p tal:content=&quot;context/Description&quot; />
      • <div tal:content=&quot;structure context/body &quot; />
      • </body>
      • </html>
    • That’s It
      • < break to demo using example.dexterity >
    • Adding a new Feed Format
      • This trivial act is left as an exercise for the reader
    • But there’s a vice sprint going on this weekend!
      • http://www.openplans.org/projects/plone-conference-2008-dc/vice
    • Inbound Story?
      • Ajax approach: plone.syndication.inbound
      • Persistent approach: feedfeeder
        • http://plone.org/products/feedfeeder
    • How to get involved
      • Did I mention the sprint?
      • Join the mailing lists:
      • http://www.openplans.org/projects/vice/lists
        • Developer list: vice-dev@lists.openplans.org
        • Discussion list: vice-discussion@lists.openplans.org
    • Questions?