While the term SOA was lost to marketers years ago, the underlying concept may be in the process of making a comeback. Though the term itself has become a bad word outside of the most conservative enterprises and suppliers today, constructing applications from services has clear and obvious benefits. In his instant classic post about his time at Amazon, Google’s Steve Yegge described Amazon’s journey towards an architecture composed of services this way:
So one day Jeff Bezos issued a mandate…His Big Mandate went something along these lines:
1) All teams will henceforth expose their data and functionality through service interfaces.
2) Teams must communicate with each other through these interfaces.
3) There will be no other form of interprocess communication allowed: no direct linking, no direct reads of another team’s data store, no shared-memory model, no back-doors whatsoever. The only communication allowed is via service interface calls over the network.
4) It doesn’t matter what technology they use. HTTP, Corba, Pubsub, custom protocols — doesn’t matter. Bezos doesn’t care.
5) All service interfaces, without exception, must be designed from the ground up to be externalizable. That is to say, the team must plan and design to be able to expose the interface to developers in the outside world. No exceptions.
6) Anyone who doesn’t do this will be fired.
Like Cortez’s soldiers, the Amazon employees got to work if for no other reason than they had no choice. The result, in part, is the Amazon you see today, the same one that effectively owns the market for public cloud services at present. Much as enterprises have historically writen off Adrian Cockcroft’s Netflix lessons with statements like “it only works for ‘Unicorns’ like Netflix,” most have convinced themselves that the level of service-orientation that Amazon achieved is effectively impossible for them to replicate. Which is, to be fair, likely true absent the Damoclean incentive Bezos put in place at Amazon. What’s interesting, however, is that many of those same enterprises are likely headed towards increased levels of abstraction and service-orientation, whether they realize it or not.
The most obvious example of this trend at work is the unfortunately named (Mobile) Back-end-as-a-Service category of providers. From Built.io to Firebase to Kinvey to the dozen other providers in the space, one the core value propositions is shortening the application development lifecycle by composing applications from a collection of services. Rather than building identity, location, and similar common services into the application from scratch, BaaS providers supply the necessary libraries to access externally hosted services. Which means that the application output of these providers is intrinsically service-oriented by design.
Elsewhere, in the adjacent Platform-as-a-Service space, providers are essentially advancing the same concept. In building an application on Engine Yard or Heroku, for example, developers are not required to implement their own datastores or caching infrastructure, but rather may leverage them as services – whether that’s Hadoop, MongoDB, memcached, MySQL, PostgreSQL, Redis, or Riak. Even IBM is planning to make the bulk of its software catalog consumable as a service by the end of the year. Which is logical, because the differentiation for PaaS providers is likely to be above the platform itself, as it is in the open source operating system market.
Consider on top of all of the above the existing traction for traditional SaaS offerings, and the reality is that it’s getting harder to build applications that are not dependent in some way upon services. And for those applications that are not yet, vendors are likely to make it increasingly difficult to maintain that independence as they move into services as a hedge against macro-issues with the sales of stand alone software.
There’s a reason, in other words, that micro-services are all the rage at the moment: services are how applications are being built today.
微服务学习资料汇总 - 马开东博客 says:
July 9, 2014 at 11:20 am
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