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by Udi Dahan.
Original Post: Predictably SOA
Feed Title: Udi Dahan - The Software Simplist
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Feed Description: I am a software simplist. I make this beast of architecting, analysing, designing, developing, testing, managing, deploying software systems simple.
This blog is about how I do it.
Paul asks about predictable response times for services - my question: if it's fast, does it matter? Between 1 and 2 milliseconds there is huge variability, meaning low predictability. My second question: if it's slow, does it matter? Between 21 hours and 22 hours there is much lower variation, thus higher predictability. When working asynchronously, we design around predictability because the real world just isn't predictable. This does NOT mean that response times don't matter. This is where SLAs come in. I can offer a service under various SLAs. If you're willing to pay me $X per message, then I'll be willing to offer you an SLA entailing the fact that your message will be processed and you will receive a result in under 2 seconds with 95% certainty. If you're not willing to pay anything, then I may offer a default SLA with much lower levels of certainty. It's all about the business demands and expected returns that influence these SLAs....
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