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RSS 2.0 content summary

xiaoxiao2021-03-06  26

Level: Getting Started

James Lewin

(Jim@lewingroup.com) President, THE LEWIN Group 2004 January

since

Since the RSS on the RSS last exam, the RSS world has changed: two new specifications have become one of the most popular XML standards, which has emerged. RSS has contributed to the rapid rise of WebLog and is becoming the standard part of other Web sites. This article reviews RSS 2.0 and examines the new development of RSS to help you quickly understand this important format.

Since I last wrote the article about RSS for DeiPelWorks, "An Introduction TO RSS News Feeds" has passed for three years. At that time, RSS was one of the more popular XML applications. Later, Netscape gave up this format, there were five types of RSS specifications (there were 5 kinds of), and there were also serious differences on this format.

Despite these defects, RSS is still unprecedented.

RSS is everywhere! Today, you can find thousands of RSS feeds. WebLog users, news publishers, government agents, and many individuals and commercial Web sites support this format. Java technology, Perl, PHP, Python and other major programming languages ​​provide developers with tools for processing RSS. Many readers and aggregates are working in web, desktop or even e-mail clients. RSS has become a chain content and metadata facts on the Internet.

This article will observe the current RSS 2.0 specification. I am not preparing to discuss colorful features and arguing around it, otherwise I can't discuss anything else.

Instead, this article will provide you with a small amount of background knowledge, examining this format, and list some tools that are popular with this format. The specific details of this format will be discussed, give you some examples, and explain what you need to know before the start. Finally, this article will involve some new features of RSS 2.0. At the end of the article, you will find a rich ore - a list of long and annotated RSS references.

What is "RSS"? I have to see who you ask! Like many standards, it is difficult for people to agree even if the most basic aspects. Some people say that "RDF Site Summary (Summary)", others say "Really Simple Syndication", and some people believe it represents "Rich Site Summary". " According to Dave Winer (he is the author of the current specification), "about what does not have any consistency of RSS, it is not a first letter, but a name. The latest version of the specification may call it an abbreviation word, I hope Not affecting too many applications. "In any case, RSS represents one thing - a format of chain on the Internet.

What is RSS? RSS is a format of chain content and metadata on the Internet. Usually used to share the title and the link to the news article. For news articles, the real article is not necessarily shared, but metadata about the article is usually shared; this metadata can contain headings, URLs or summary. For publishers, RSS is an important tool because of the provision of the chain and integrate the third party's content into your site.

RSS is an XML dialect. All RSS files must meet the XML 1.0 specification published on the World Wide Web Consortium, W3C) Web site. Here is a typical example, explaining how to use RSS:

A publisher has some desirable content. They created an RSS channel for these contents. Some items on this channel containing web pages wishing promotion. This channel can be read and converted into title and links by a remote application. These links can be added to a new web page or for specialized readers. People see this link from different sites, click on the connection to the initial publisher's website.

Although the title chain is the most common RSS usage, it can also be used for other purposes. RSS is a very popular format in the WebLog community. It is also used for photo books, classified ads, recipes, comments, and tracking software packages.

RSS is used as a way to deliver information in e-commerce. For example, Amazon provides news to customers based on its Web service platform. This allows you to learn about the best-selling books in your news reader, or include information about the related books sold by Amazon in your Web site.

In the past few years, RSS has an amazing growth in popularity. Syndic8.com maintains an RSS channel index, and its balance is less than 1400% in two years. Yahoo News, BBC, SlashDot, Lockergnome, Amazon, CNN, Wired, Rolling Stone, and Apple Computer are located in many of the most popular RSS feeds.

DeveloperWorks RSS feeds developerWorks provides its own RSS feed, see http://www 106.ibm.com/developerWorks/RSS/.

News readers have a new software type with the increase of news, and there is a new software type: news reader. News Readers are personal aggregat - help you discover and organize a list of channels. Once you have selected the channel, you can use the interface that is consistent with the connector. News Readers Check the update of the channel you are interested in and transform into HTML that can be viewed.

A popular news reader is blogExpress:

Figure 1. View alphaworks in BlogExpress

BlogExpress is the so-called "Pizza Software" - means that if you like this software, you can send some money to buy a pizza.

Custom channels add a channel in BlogExpress. For example, you are interested in tracking activities at the IBM AlphaWorks site. The first thing you have to do is take a summary of the increase:

Figure 2. News findings found in AlphaWorks

Add a summary, orange "XML" logo is often used to link public RSS feeds. In most web browsers, you can right-click the "XML" flag to copy link and paste into your news reader.

Other common news readers include Blogstreet, FeedReader, Amphetadesk, and Newsgator (see Resources).

Discover RSS, you can use the search engine to find the contents of the RSS format. For example, when using Google, you can add "FileType: RSS" to search for the lookup item in the .rss file.

Special search engines make content search easier. Feedster monitors WebLog and allows you to look up through a log item index, view it according to Correlation, Date, Logrank. When you are searching, Feedster creates an RSS feed asking for your request. This feed can be added to your news reader so you can see all the latest activities related to search requests, and you don't even need to leave the news reader.

Daypop Search News, BLOG and RSS. It allows you to track popular news in WebLog world. It provides the current most popular 40 WebLog links. This is the link between the world's most popular articles. It creates a list of the most popular vocabulary used in WebLog. It also provides a weblog list that is the most popular WEBLOGGER. You can also customize your search. Rating lists and custom searchs have RSS's own form, you can import your news reader. The new feature of RSS 2.0 RSS 2.0 is based on the RSS 0.91 specification. It is backward compatible, so any tool for processing RSS 2.0 should also handle 0.91 summary. The upgraded specification adds a small amount of elements, such as and .

It also removed some restrictions. In the past, and elements can only be HTTP or FTP, and any valid URI can now be used. In RSS 0.91, each channel can only contain 15 items, and the length of the element is also limited, and now these restrictions are canceled. But you should still be careful to use a large value because they may have problems with old applications.

However, a greater change is to expand this format using the namespace. RSS 2.0 supports namespaces, a standard method for increasing elements that are not in specifications. As long as defined in a namespace, the brow can contain new elements.

RSS 2.0 Overview RSS is an XML dialect for chain web content and metadata. RSS 0.91 is the most commonly used version of available versions. For new RSS feeds, a better way is to use version 2.0 because it is a current specification, and as mentioned earlier, it is compatible with 0.91.

Dave Winer wrote a version 2.0 version. The modification of the specification may become difficult to use, or damage the existing application, and he consciously avoids this situation. Winer summarized his thoughts: "It is simple. This is the value of RSS. Anyone who is slightly HTML can understand the RSS. This is extremely important!"

This specification is issued under the Creative Commons license (see Resources). This means you can copy and distribute this specification for free and derived, and freely for business work. An advisory committee is responsible for updating norms, promoting specifications and writing documents.

The RSS file form RSS file consists of a element and its sub-elements. In addition to the channel content itself, also includes an element in the form of an item, such as , <link>, and <design>. Items are usually the main part of the channel, including content that often changes.</p> <p>The channel channel generally has three elements, providing information about the channel itself:</p> <p><title>: The name of the channel or the nickname. <link>: The URL of the Web site or site area associated with the channel. <Description>: Briefly introduces what this channel is doing.</p> <p>Many channel sub-elements are optional. Commonly used <image> elements contain three essential child elements:</p> <p><URL>: Indicates the URL of the GIF, JPEG, or PNG image of the channel. <Title>: Description of the image. When the channel is presented in HTML, it is used as an Alt property of the HTML <image> tag. <link>: The URL of the site. If the channel is presented in HTML, the image is used as a link to this site.</p> <p><image> There are three optional sub-elements:</p> <p><width>: number, indicating the pixel width of the image, the maximum value is 188, the default is 88. <height>: numbers, indicating the pixel height of the image. The maximum is 400, the default is 31. <Description>: Contains text, which can be used as a title attribute that surrounds the link elements formed around the image. Also, many other optional channel elements can also be used. Most are themselves:</p> <p><Language>: EN-US <Copyright>: Copyright 2003, James Lewin <managingEditor>: dan@spam_me.com (dan deletekey) <WebMaster>: dan@spam_me.com (dan deletekey) <Pubdate>: SAT, 15 NOV 2003 0:00:01 GMT <LastBuilddate>: SAT, 15 Nov 2003 0:00:01 GMT <category>: Ebusiness <Generator>: Your CMS 2.0 <DOCS>: http://blogs.law.harvard.edu/ TECH / RSS <Cloud>: Allows the process to register as "Cloud", inform it when the channel is updated, to implement a lightweight publishing - subscription protocol for RSS. <TTL>: Survival time is a number, indicating that the number of minutes buffered before refresh. <Rating>: About the PICS evaluation of the channel. <textInput>: Defines the input box that can be displayed with the channel. <SkiphouRs>: Tell the aggregator which hours updates can be ignored. <SkipDays>: Tell the aggregator's update that the day can be ignored.</p> <p>Items are usually the most important part of the short. Each item can be recorded about a WebLog, a full document, a movie review, a classified ad or any desired content that is hoped with the channel chain. Other elements in the channel may remain unchanged, but items often change.</p> <p>You can have any multiple items. The previous specification limit is 15 items. If you want to keep backward compatibility, this is still a good upper limit.</p> <p>Elements of news items typically contain three elements:</p> <p><title>: This is the name of the item, converted into the title in HTML in standard applications. <link>: This is the URL of this item. Title is usually used as a link to point to the URL included in the <link> element. <Description>: Usually a summary or complement to the URL pointed to by the LINK.</p> <p>All elements are optional, but one item is at least either contains <title>, or contains one <description>.</p> <p>There are other optional elements:</p> <p><author>: The author's E-mail address. <category>: Supports organization records. <Comments>: About the URL of the note page. <enclosure>: Supports the media object related to this item. <Guid>: The only permanent link to this item. <pubdate>: When is this item released. <source>: This item is from which RSS channel that is very useful when the item is aggregated. Listing 1 is an example of an RSS 2.0 file. Note that the channel is included in <RSS Version = "2.0">. This is a very basic example, explaining how the items and images are included in the channel. The elements shown are most commonly used channel sub-elements.</p> <p>Listing 1. Example RSS 2.0 file</p> <p><? XML Version = "1.0"?></p> <p><RSS Version = "2.0"></p> <p><channel></p> <p><title> the channel's name goes here </ title></p> <p><link> http://www.urlofthechannel.com/ </ link></p> <p><Description> This Channel Is An Example Channel for an Article.</p> <p></ description></p> <p><Language> EN-US </ Language></p> <p><iMage></p> <p><title> The Image Title Goes here </ title></p> <p><url> http://www.urlofthechannel.com/images/logo.gif </ url></p> <p><link> http://www.urlofthechannel.com/ </ link></p> <p></ iMAGE></p> <p><item></p> <p><title> The fulure of content </ title></p> <p><link> http://www.itworld.com/nl/ecom_in_act/11122003/ </ link></p> <p><Description> The Issue of People Distributing and Reusing</p> <p>Digital Media Is A Problem for Many Businesss. It May Also Be</p> <p>a hidden opportunity. Just As Open Source Licensing Has Opened</p> <p>Up New Possibilities in the World of Technology, IT Promises to do</p> <p>The Same in the area of ​​create content. </ description></p> <p></ item></p> <p><item></p> <p><title> Online Music Services - Better Than Free? </ Title></p> <p><link> http://www.itworld.com/nl/ecom_in_Act/08202003/ </ link></p> <p><Description> More People Than EVER ARE Downloading Music from</p> <p>The Internet. Many Use Person-to-Person File Sharing Programs Likekazaa To Share and Download Music in MP3 Format, Paying Nothing.</p> <p>THIS HAS Made It Difficult for Companies To Setup Online Music</p> <p>BusinessS. How Can companies Compete Against Free? </ description></p> <p></ item></p> <p></ CHANNEL></p> <p></ rss></p> <p>Related Tools Due to the popularity of RSS, many tools have enable you to use these files substantially in any environment:</p> <p>Java technology: A RSS Utilities Package found on the Sun Site, supports using Tag Library in JavaServer Pages. It also includes an RSS parser. Perl: There are several Perl tools that process RSS. XML :: RSS provides a framework for creating and maintaining the RSS file. It supports conversion between common versions. Python: rss.py is a set of classes that use the RSS channel through Python.</p> <p>In addition, many content management and WebLog tools also support RSS directly. Most WebLog tools, including Movable Type, Blogger, and Radio Userland support RSS. Some content management systems, including Zope and CityDesk, now support it.</p> <p>Extending RSSRSS 2.0 has many optional elements, including those required by most channels. But it also supports scalability, so you can use the elements in the specification. However, the RSS 2.0 specification does not spend how much time definitions implement extension. Regarding the scalability, the specification is summarized as: "RSS will include the elements not described in this page as long as these elements are defined in a namespace."</p> <p>This has left a big imagination space! Fortunately, the specification contains an example where you can refer to several examples currently.</p> <p>Basic ideas are that you can increase the required labels - but increases the elements with multiple meanings. People who use your channel may not know what a tag is meaningful. For example, if I want to use the <analog> tag in a channel, it is not very clear. Web experts may think this label refers to analog, which is the most popular Web Log file analyzer. Science fi may think this label is about Analog, a classic science magazine. Musicians may think that it refers to popular synthetic types, and biologists believe that this is an organ, and electronic engineers are considered to be a circuit. The ambiguity makes people understand the meaning of the label.</p> <p>Therefore, RSS allows you to add anything you like, but require it to be used with namespaces. This helps clarify the meaning of the label.</p> <p>Go back to <Analog>, I may want to create a group of tags about e-commerce and let the <analog> tag as a "e-business" element. To this end, I added the following namespace:</p> <p>XMLns: ebusiness = "http://www.lewingroup.com/ebusinesschannel"</p> <p>This creates a namespace called "ebusiness" and indicates the documentation of this name space on my site. In order to use the <analog> tag, I can use this format: <ebusiness: analog>. This will distinguish between other similar meanings, such as <ScienceFiction: Analog> or <Synthesizers: analog>. Regarding the scalability, a more practical example can be found in the sample file of the RSS 2.0 specification:</p> <p>Listing 2. RSS 2.0 specification sample space in the sample file</p> <p><? XML Version = "1.0"?></p> <p><! - rss generated by radio userland v8.0.5 on 9/30/2002; 4:00:00 am pacific -></p> <p><RSS Version = "2.0" XMLns: blogchannel = "http://backend.userland.com/blogchannelmodule"></p> <p><channel></p> <p><title> scripting news </ title></p> <p><link> http://www.scripting.com/ </ link></p> <p><Description> A Weblog About Scripting and Stuff Like That. </ description></p> <p><Language> EN-US </ Language></p> <p><blogchannel: blogroll></p> <p>Http://radio.weblogs.com/0001015/Userland/scriptingnewsLeftlinks.opml</p> <p></ blogchannel: blogroll></p> <p><item></p> <p><Description> Joshua Allen:</p> <p><a href="http://www.netcrucible.com/blog/2002/09/29.html#a243"></p> <p>Who loves names? </a> </ description></p> <p><Pubdate> Sun, 29 Sep 2002 19:59:01 GMT </ pubdate></p> <p><guid></p> <p>Http://scriptingnews.userland.com/backissues/2002/09/29#when:12:59:01pm</p> <p></ guid></p> <p></ item></p> <p></ CHANNEL></p> <p></ rss></p> <p>In this example, a namespace called BlogChannel is defined. It points to a document that explains several commonly used new elements for WebLog. One of them is <blogroll>. Document Description, Blogroll is a link collection in WebLog, pointing to sites related to your WebLog content.</p> <p><BlogChannel: blogroll> tag provides information needed by users or software, knowing Blogroll is an element defined in the BlogChannel namespace and finds the location of this document.</p> <p>Similarly, RSS 2.0 requires a namespace for elements that are not specified. All basic labels assume that in the RSS 2.0 namespace. This makes this format more easily because you don't need to know the namespace at all unless you need to expand the RSS.</p> <p>Conclusion This paper examines the importance of RSS in content chain and aggregation. The article mainly discusses RSS 2.0 because this is the latest version of the specification, and is rapidly popular. This article also examines the tools that process RSS, including agglomerates, verification programs, and parsers. For more information, please refer to the reference. Reference</p> <p>Read the author About RSS Previous DeveloperWorks article, "An Introduction to Rss News Feeds" (DEVELOPERWORKS, November 2000), discussed with version 0.91. Look at the common news reader:</p> <p>BlogExpress Blogstreet FeedReader amphetadesk newsgator Try the following to establish a popular tool for WebLog and newsletter:</p> <p>Blogger CityDesk Movable Type Radio Userland Zope uses two RSS authentication programs, userland, and feedvalidator. Read the RSS 2.0 specification in the Harvard Law School Site. Requires the explanation of the different versions of RSS, please read the XML.com article "What is rss?" In Mark Pilgrim. More articles and resources about this topic can be found on the Oasis RSS page. Understanding how to use RSS through Java technology through the SUN developer website. View the WirelessDevnet article, "Parsing XML with PHP", the author is Marc Robards. Learn how to develop an RSS Viewer Applet for navigation and viewing the RSS channel. Read the discussion on the Creative Commons project (DeveloperWorks, May 2003) column. The RSS specification is released under the Creative Commons license.</p> <p>Bringing:</p> <p>DeveloperWorks provides its own RSS feed, see http://www-106.ibm.com/developerWorks/RSS/. Several technical classifications for connecting to alphaWorks. More technical content, try O'Reilly Network. Visit the Sun Developer Network Content Syndication Program. Don't let this long name make you stay away from its RSS. IT news from INFOWORLD to IT news. Look at Lockergnome - it holds serious attitude towards RSS.</p> <p>Some mainstream baking resources:</p> <p>Access Wired's chain news. Want to find the most popular WebLog? You can get the help you need at Daypop and Feedster. Try a way in Syndic8 in a variety of search news. Canada likes RSS! Access to Government of Canada Web Site, this is a good example of the public uses RSS. 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