1. RSSWhat is it and how do we use it? Alex Pline 14 July 2005 February 2010 Tired of having to navigate to a bunch of your favorite Web sites everyday to find out what's new? Really Simple Syndication (RSS), an XML-based format for content distribution, is one of the hottest things on the web today and will make your life MUCH easier. RSS feeds bring automatically updated information straight to your desktop. You can monitor news, web site updates and "podcasts” in a variety of easily accessible ways.
2. 2 RSS Brownbag Agenda What is XML and RSS? History of RSS Basic technology and its use Tools for utilizing RSS Specific examples of how ESMD is using RSS Demos Bleeding Edge – Real Time RSS The “Other” RSS Formats
3. What is XML? Fundamentals: What is XML? Set of rules for formatting content of electronic documents Basic rules are a W3C open standard XML documents are plain text consisting of markup (hierarchical sets of elements in <>) Can be a predefined set Can be anything an author chooses as long it conforms syntactically to the XML standard Meant to be machine readable Examples Predefined: RSS, Office Open XML (.docx), MathML, Semantic Web languages RDF and OWL Custom: Many applications use homegrown XML as a way to represent hierarchical information like items in a menu structure 3 A homegrown example: <?xml version="1.0" encoding="utf-8"?> <alexXML> <firstElement> SOME CONTENT <secondElement> SOME CONTENT <thirdElement> FIST INSTANCE CONTENT </thirdElement> <thirdElement> SECOND INSTANCE CONTENT </thirdElement> <thirdElement> THIRD INSTANCE CONTENT </thirdElement> </secondElement> </firstElement> </alexXML>
4. 4 What is RSS? RSS stands for either: “Really Simple Syndication” (garden variety XML) Or “RDF Site Summary” (RDF-based XML) Regardless of version, they “do” the same thing Do we need (only!) two RSS versions? (more on this later) What Does RSS “Do”? Applications use RSS to “pull” information snippets to your computer/phone/PDA via XML Information is most often Web site updates, but can be any type of “stuff” someone wants to distribute In the news world this is known as “syndication” Transparent to the end user Lots of ways to use RSS
5. RSS History “Marketplace Confusion”: Development of RSS has a checkered past Arguments between developers and companies Competing formats: simple xml v. rdf No clear “standard”; no “standards body” involved in the development Abbreviated Development History 3/15/99 - RSS 0.90, Netscape. The only thing about it that was RDF was the header, otherwise it was plain garden-variety XML. 7/10/99 - RSS 0.91, Netscape. The RDF header is gone. 6/4/00 - RSS 0.91, Userland adopts specification. 8/14/00 – RSS 1.0 published as a proposal, Rael Dornfest (O'Reilly). Based on RDF and uses namespaces. Like 0.90 it has an RDF header, but otherwise is a brand-new format, not related to any previous format. 2/25/00 - RSS 0.92, Userland. RSS 0.91 with optional elements. 4/20/01 - RSS 0.93 discussed but never deployed. 9/18/02 - RSS 2.0, Dave Winer (formerly w/Userland). RSS 0.92 with optional elements. While in development, this format was called 0.94 7/15/03 - RSS 2.0 spec released through Harvard under a Creative Commons license (including <cloud>). ~2005 – iTunes specific namespace The next RSS related fight: real time updates - <cloud> or PubSubHubbub 5
6. RSS Technology and Usage An “RSS feed” is just a simple XML file that contains information about the contents of a site Metadata about the feed Title, publish date, publisher, link, description et al Metadata about items in the feed Description, Link URL et al Extent of information beyond pure metadata at content owners discretion – typically snippet, sometimes full content Most commonly used for News, Blogs, Podcasts (“audio blogs”) Virtually all major Web sites now have RSS feeds Many applications now utilize/support RSS Feeds are created/updated by programs, not manually Used for Web 2.0 “services” to exchange information RSS is XML so it is easily “reused” via XSLT 6
8. Podcast Example “Podcasts” are just RSS 2.0 Feeds with additional elements <enclosure> tells the RSS reader the location (URL) to the audio/video file 8
9. iTunes Podcast Example The usual stuff: Feed metadata The usual stuff: Feed content <itunes: > namespace is an apple specification for publishing podcasts on the iTunes music store 9
10. Use Cases: Why Use RSS? Browse LOTS of headlines quickly - like scanning the newspaper but in a simplified, chronological way - “River of News” 10
11. Use Cases: Why Use RSS? “Subscribe” to Web site information anonymously since no personal information about you is known by the information provider No information to “leak” Aggregating information (providers) and subscribing to information (end users) Audio and video programming (“podcasts”) Web site/blog updates “Mashups” of multiple content sources 11
12. 12 Methods To View RSS Feeds “Live” Bookmarks in browsers Items in feeds appears as “Bookmarks” in your browser Mozilla Firefox (all platforms), Apple Safari (Mac), IE 7 Pro: Manage the feeds in the application that views the full items Con: bookmarks are hard to navigate quickly and are local to that browser e-Mail programs Each item in a feed appears as an e-mail Outlook 2007, Mozilla Thunderbird Pro: Benefits: many people like and understand the concept of “e-mail newsletters” Con: Have to manage items like e-mail
13. Methods To View RSS Feeds (cont.) Web-based Google Reader, iGoogle, Yahoo Portal Pro: Access to the same RSS lists and state (read/unread) from anywhere in the “cloud” Con: Host knows what you read Stand Alone “RSS aggregators” or viewers Awasu, FeedDemon, Newsgator An antiquated concept given RSS integration with other apps (browsers, e-mail clients, iTunes for podcasts) Pro: some “purists” like the separation, works great in the case of podcasts in the iPod/iTunes world Con: Another stand alone local application 13
14. How To Subscribe To RSS Feeds Manually Look for the “XML button” (or similar) on Web sites Copy the link URL and paste it into your favorite RSS tool When you view the feeds in the tool, they will update (YMMV) In the browser View the feed and add it as a bookmark When you look at that bookmark it will automatically show new items in the feed Click the link – many sites have widgets which integrate with on-line readers Podcasts in iTunes – you are subscribing to RSS feeds without even knowing it! 14
15. Demos Subscribing to feeds IE, Safari and Firefox as a reader - RSS Bookmarks Google Reader – Cloud reader Outlook 2007/Mozilla Thunderbird – RSS as email 15
16. Beeding Edge - Real Time RSS One of the issues with RSS is that it is a PULL technology – a user (or user agent) has to go and “check” or “pull” or “poll” feeds Two current competing protocols for PUSH technology – a user (or user agent) is notified that the feed has changed RSS Cloud – Dave Winer Lightweight, easier to implement A distributed “headline” twitter-like infrastructure PubSubHubbub Heavier solution, harder to implement Includes payloads Not clear which or both will succeed Both ideas also get at the problem of “Big Company Control” of social media streams which is a problem with centralized social networks like Twitter and Facebook 16
17. The “Other” RSS Formats RDF Site Summary is an RDF-based XML vocabulary for syndication RDF is significantly more complex than RSS 2.0 (for a human) Why use RDF, it’s so complicated? Goes beyond just stand-alone “News Syndication” A Semantic Web enabler: provides a higher level of semantics to the data Allows mixing with other RDF vocabularies Examples: Dublin Core (DC), Friend of a Friend (FOAF), Description of a Project (DOAP) ATOM A very RSS 2.0-like XML format ATOM is an IETF standard Reasonable uptake Most readers recognize these XML flavored feeds too 17
20. 20 Summary RSS is mainstream RSS is changing has changed the way information is consumed by humans AND machines Good, and growing, application support but little authenticated feed support RSS is easy to use and requires little or no understanding of the underlying technology NASA and ESMD are making good use of RSS for internal and external communications RSS is becoming “real time”
21. Further Reading Resources CNet RSS Primer – http://www.cnet.com/4520-6022-5115113.html What is RSS- http://www.xml.com/pub/a/2002/12/18/dive-into-xml.html RSS 2.0 Specification - http://blogs.law.harvard.edu/tech/rss RSS 1.0 Specification - http://web.resource.org/rss/1.0/spec RSS in Outook 2007 - http://office.microsoft.com/training/training.aspx?AssetID=RC102254891033&pid=CR100654581033 NASA RSS Feeds – http://www.nasa.gov/rss Real Time RSS - http://thenextweb.com/2009/09/08/publish-recieve-r-realtime/ RSS Decentralization - http://radar.oreilly.com/2009/09/rss-never-blocks-you-or-goes-d.html 21
Notas del editor
RSS is a technology that has revolutionized the way we distribute and consume information. It’s a technology that has been around for about 10 years, but has really blossomed in the Web 2.0 world because it facilitates interesting use and reuse of syndicated information. This talk will discuss what it is, how it works and how end users can utilize it to make consuming content easier and faster. As the title suggests, there are some additional side benefits to using RSS.
Before I can start talking about RSS, I need to level set everyone on what XML is since RSS is really just a special case of XML. XML is a set of rules for formatting content of electronic documents. The set of rules in an open standard controlled by the World Wide Web Consortium (W3C) and maintained by a very large community. XML documents are essentially just standard text documents consisting of “Markup Language”, just hierarchical sets of elements in angle brackets. The elements can be predefined sets that may or may not be open standards, or they can be created adhoc and used for any purpose a creator might have. Regardless of the format, these rules allow machines to easily “parse” or read this information.Predefined examples include: RSS, Office Open XML (.docx) the new MS Office 2007 formats, MathML a markup language that represents mathematical concepts and the Semantic Web languages RDF and OWL.Custom examples include using homegrown XML as a way to represent hierarchical information like items in a menu structure or as a specific representation of data in a database.In general, using an existing format makes interoperability much easier, although I’ll make a comment on that when we talk about the “other RSS”. Included here are some examples of both existing predefined formats and an example of an adhoc format that I created.One thing to note about XML files: typically they contain ONLY data and metadata, and do not contain information that about how that data should be represented visually. In the case of a web context, this means that there is no presentation information (ie what it should look like), this is accomplished using stylesheet technology (another W3C standard).
Now that we have a basic understanding of XML, I can describe what RSS is. RSS stands for “Really Simple Syndication” (garden variety XML) or “RDF Site Summary” (RDF-based XML), but ostensibly RSS is a specific flavor, or flavors of XML. Regardless of which format we are referring to, they do the same thing.In general, users don’t interact with RSS directly because it’s meant to be machine readable. Because RSS is machine readable, applications use RSS to “pull” information snippets to your computer/phone/PDA via these XML formats. Information is most often Web site, blog or social media site updates, but can be any type of “stuff” someone wants to distribute (more on that later). Think of this information as web content that is in “raw form”, ie just data and no “presentation layer”. It’s up to the receiver to display the information in whatever way it was designed.In the news world this is known as “syndication”. There are lots of ways to use RSS, but the nice thing about this technology is that it sits on top of the robust infrastructure of the web – the http protocol which every web server, web application and web browser and many desktop applications already use.
RSS has a very checkered past. If you follow the history, you quickly see that it is a case study for what happens when cooperation v. competition is out of balance, in the same vein as the “Browser Wars” of the 1990a. Typically all stakeholders benefit in the long run when this kind of technology is progressed under the auspices of a standards body.
Why would you want to user RSS? Think of the two ways you might read a news paper or magazineBrowsing Headlines:There are multiple ways to consumer web-based content. You caUsing my reader (Google Reader) I can browse the contents of 50 web sites x Avoids the mailing list “problem”.
Both PuSH and rssCloud address a fundamental flaw in the way web applications work today. Currently, getting updates on the web requires constant polling. Subscribers are forced to act like nagging children asking, “Are we there yet?” Subscribers must constantly ping the publisher to ask if there are new updates even if the answer is “no” 99% of the time. This is terribly inefficient, wastes resources, and makes it incredibly hard to find new content in as soon as it appears. Both protocols flip the current model on its head so that updates are event driven rather than request driven. Both protocols eliminate the need for polling by essentially telling subscribers, “Don’t ask us if there’s anything new. We’ll tell you.”
