Cloud Foundry: Design and Architecture
Derek Collison discusses the goals, the design premises and patterns employed in creating the architecture of Cloud Foundry, VMware’s open source PaaS, unveiling internal architectural details.
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Real Time Web And Cloud Management Standards
Posted by Dilip Krishnan on Feb 18, 2010
William Vambenepe comments on the absence of “real time” features in existing cloud management solutions and proposes the desirable properties that define such solutions
Events/alerts/notifications have been a central concept in IT management at least since the first SNMP trap was emitted, and probably even long before that. And yet they are curiously absent from all the Cloud management APIs/protocols.
He links to articles of experienced cloud practitioners, expressing their frustration with the absence of real time features in the cloud management API’s of the various cloud providers.
RightScale’s Thorsten von Eicken was first to request “an event based interface instead of a request-reply based interface”, pointing out that “we run a good number of machines that do nothing but chew up 100% cpu polling EC2 to detect changes”. George Reese seconded and started to sketch a solution.
He goes on to define the framework of features that will facilitate the real time cloud management solutions and describes them in detail.
- Event formats
- Subscription creation
- Subscription management
- Subscription expiration
- Delivery reliability
- Delivery mechanism
- Security
- Throttling
While such standards may not exist in the cloud management domain, its not to say that the foundations for real time communication exist in the consumer space with the likes of FriendFeed, Twitter, Google Wave etc. Dare Obasanjo examines implementations of the real time web that is already available today and provides a detailed explanation of the technologies such services use.
“The real-time web” has become popular as a way to describe burgeoning trends and technologies related to consuming web content as soon as it is created. However […] there is often difficulty in understanding where the technical details end and where the hype begins.
"What Features and Functionality Make Up the Real-Time Web?", he elaborates,
Refreshing a web page as new updates are available without reloading the page. A good example of this is seen when performing a search on Twitter
Receiving notifications on content updates as soon as they happen instead of polling. An example of this is the fact that user status updates from Twitter appear within a second on FriendFeed when the user has hooked up both services.
Some people consider the universe of status updates on sites like Facebook and Twitter [that] provide search functionality over this data.
He goes on to explore solutions that provide the capabilities of the real time web and the various players in the space.
* Bringing Real-Time to AJAX: COMET, Long Polling and soon Web Sockets- COMET typically refers to keeping a permanent open connection between a browser and a server using a number of techniques. One approach is the hidden iframe technique.
- Another common technique is long polling. With this approach the browser application makes an asynchronous request for data from the server either using XMLHttpRequest or a script tag. Once data is returned, another request of the same type is made. The essentially permanently keeps an open connection between the browser and the server.
- The W3C’s HTML 5 working group is working on making COMET part of the next generation of HTML with the creation of the WebSockets specification.
* Notifications at the Speed of Light: Go Beyond Polling with PubSubHubbub- Since polling is an inefficient way to get content updates […] a couple of Google employees have proposed the PubSubHubbub protocol (commonly abbreviated as PuSH) as a way to bring real-time notifications to content syndication on the Web. There are already a number of sites consuming and producing PubSubHubbub including MySpace, LiveJournal, Google Reader, Tumblr and FriendFeed.
* Creating and Consuming Fire Hoses: The Lynchpin of Real-Time Search- Being able to analyze status updates [from sites like Twitter and Facebook] as they occur to determine people’s sentiments on a news event as it occurs or detect breaking news is a rapidly growing space with lots of players including Microsoft’s Bing, Tweetmeme and Sysomos among others.
Is the real time web a grassroots solution to cloud management standards? More information is available at their respective blogs.
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