Google AJAX Feed API

Preliminary research

Link: http://code.google.com/apis/ajaxfeeds/documentation/
With the AJAX Feed API, you can download any public Atom or RSS feed using only JavaScript, so you can easily mash up feeds with your content and other APIs like the Google Maps API. JavaScript and XMLHttpRequest use the Same-Origin Policy (SOP). With this policy, scripts can access data from the same host from which the containing page of HTML was served, but not other hosts. This protects users from certain classes of scripting attacks, but prevents many developers from writing AJAX-based mashups. The Google AJAX Feed API offers a simple workaround to these restrictions for a specific type of content available on the web: syndication feeds.

Description:

Pre requirements for developers:

People should be familiar with JavaScript programming and object-oriented programming concepts.

Based on Technologies:

The AJAX Feed API can return feeds in two formats: JSON and XML (or in combined JSON/XML Result Format). By default, the API returns the feed in the JSON format.

Functionality:

  • Supported Feed Formats
    • Atom 1.0
    • Atom 0.3
    • RSS 2.0
    • RSS 1.0
    • RSS 0.94
    • RSS 0.93
    • RSS 0.92
    • RSS 0.91
    • RSS 0.9
  • Feed Crawl Frequency
The Google AJAX Feed API uses the same feed caching and sharing mechanism as Google Reader, which means that feed data from the AJAX Feed API may not be completely fresh, particularly for frequently updated feeds. The Google feed crawler ("Feedfetcher") retrieves feeds from most sites less than once every hour. Some frequently updated sites may be refreshed more often.
  • Cached Entries
The AJAX Feed API, like Google Reader and the Google personalized homepage, caches individual entries within feeds and reconstructs feeds based on those entries. Consequently, feeds from the AJAX Feed API may not reflect the exact XML file from the URL you request. In many cases, you can request more entries from the AJAX Feed API than are currently available in the live feed. This entry-caching behavior may result in incorrect feeds if entry IDs are not maintained between feed updates or if entry order changes between requests. For example, the iTunes Top 10 Songs feed may return song entries out of order if you request it through the AJAX Feed API.
  • How Feeds are Crawled
The Google AJAX Feed API crawls feeds with Feedfetcher, which is also used for Google Reader and the Google personalized homepage.
  • Cross-Browser XML Access
Microsoft Internet Explorer does not support DOM Level 2, which means that it does not support namespace-aware DOM functions like getElementsByTagNameNS. The Google AJAX Feed API includes a cross-browser implementation of getElementsByTagNameNS since it is a common requirement for sites consuming feeds. The API does not include implementations of any other DOM Level 2 methods at this time.

Security Notes:

JavaScript uses the Same-Origin Policy (SOP) to prevent malicious scripts from accessing private user data. See the Security for GWT Applications article for an in-depth discussion on the implications of this policy and other JavaScript security issues. The AJAX Feed API does not send any private information to the host of the requested feeds. Google's crawler Feedfetcher downloads the feeds anonymously, and Google's servers act as a cache for that feed for all requests made with the AJAX Feed API. The AJAX Feed API only provides access to publicly accessible feeds.

Is it open source:

To use the API, you need to sign up for an API key. Google Webmaster Help Center
Security for GWT Applications

Google APIs
Category AJAX Frameworks
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This page (revision-7) last changed on 18:24 25-Mar-2017 by Maryna Astrouskaja.
 

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