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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Five Candidate Patterns Promoted To The SOA Patterns Master List
Posted by Jeevak Kasarkod on Aug 16, 2011
Five new design patterns were promoted from the candidate list to the master list on the community site of SOA Patterns published by Prentice Hall. These new patterns will be published in the upcoming SOA with REST book
The patterns that made the cut are:
• Content Distribution Network
• Content Negotiation
• Endpoint Redirection
• Entity Linking
• Response Caching
• Content Negotiation
• Endpoint Redirection
• Entity Linking
• Response Caching
Apart from Entity Linking, the remaining design patterns are self explanatory. Instead of the common practise of embedding entity relationship information in composition services, the Entity Linking pattern prescribes responding with links to related entities by entity services themselves. As a result consumer services can discover the entire entity relationship model as they navigate the links embedded in the responses from the entity services. This decoupling from the composition service alleviates the burden of updating the service to reflect entity relationship changes with time. Lightweight Endpoint and Reusable Contract patterns should ideally be used in conjunction with this design pattern to facilitate link navigation.
Inspired by DNS, the Content Distribution Network (CDN) pattern is a service replication pattern that leverages Brewer's CAP theorem to improve availability at the cost of consistency. Based on HTTP's Content Negotiation mechanism, the Content Negotiation pattern recommends the usage of media type as metadata in the service request and response envelopes to enable delivery of different media types using the same service capabilities. Endpoint Redirection adds permanent or temporary redirection capability to an outdated service to respond to a consumer with a redirection link to an updated version of the service. Apart from wasted runtime resources for repeated permanent redirections, the redirection link in the response is questionable from a security perspective in case the outdated service is compromised. Response caching adds caching at the messaging layer and utilizes caching metadata to prevent transmission of stale responses to redundant requests.
Inspired by DNS, the Content Distribution Network (CDN) pattern is a service replication pattern that leverages Brewer's CAP theorem to improve availability at the cost of consistency. Based on HTTP's Content Negotiation mechanism, the Content Negotiation pattern recommends the usage of media type as metadata in the service request and response envelopes to enable delivery of different media types using the same service capabilities. Endpoint Redirection adds permanent or temporary redirection capability to an outdated service to respond to a consumer with a redirection link to an updated version of the service. Apart from wasted runtime resources for repeated permanent redirections, the redirection link in the response is questionable from a security perspective in case the outdated service is compromised. Response caching adds caching at the messaging layer and utilizes caching metadata to prevent transmission of stale responses to redundant requests.
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Interesting article - Security issues?
by
Eadwin Tomlinson
Posted
Fluffy patterns
by
Richard Gell Mann
Posted
utter bs
by
just sql
Posted
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Would love to see some real examples of the entity linking to really understand its application.
I think you need to secure you own comments - you seem to be gettign spammed. -
Ok, so while we are at it why not define 'application layer protocol' as a uber-pattern? After all, in the world of these SOA champions, HTTP conneg is a pattern, HTTP 301 is a pattern, REST connectedness becomes entity linking pattern and good old HTTP caching has got a pattern too! A quick look through the SOA patterns book shows venerable examples of lofty patterns such as Asynchronous Queuing, Logic Centralization, Data Model Transformation and on and on. The SOA cow is being truly milked dry by certain individuals writing tomes of books (and selling training and certifications) with colorful pictures and elaborately worded vacuous explanations of common sense architecture and design issues that should be obvious to anyone but freshers straight out of school. An amazon.com review comment sums it up best for one such 'SOA wonderbook' - 'More is less and less would have been nothing'!
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I've got to agree with Richard. This is just another load of utter spurious rubbish to make some money off the backs of herd animals. Maybe Jeevak can move into politics instead, as this sort of unbridled nonesense rattles off the tongue of every politician the world over, every day.
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