SOFTware is HARD

To commit to memory, SLA 9s and acceptable unscheduled downtime: Availability % Approximate downtime/ year 90 50,000 minutes ( 800 hours ) 99 5,000 minutes ( 80 hours ) 99.9 500 minutes ( 8 hours ) 99.99 50 minutes ( 1 hour ) 99.999 5 minutes 99.9999 0.5 minutes In more details, for reference: Availability % Downtime/ year Downtime/ month* Downtime/ week 90% (“one 9”) 36.5 days 72 hours 16.8 hours 95% 18.25 days 36 hours 8.4 hours 98% 7.30 days 14.4 hours 3.36 hours 99% (“two 9s”) 3.65 days 7.20 hours 1.68 hours 99.5% 1.83 days 3.60 hours 50.4 minutes 99.8% 17.52 hours 86.23 minutes 20.16 minutes 99.9% (“three 9s”) 8.76 hours 43.2 minutes 10.1 minutes 99.95% 4.38 hours 21.56 minutes 5.04 minutes 99.99% (“four 9s”) 52.56 minutes 4.32 minutes 1.01 minutes 99.999% (“five 9s”) 5.26 minutes 25.9 seconds 6.05 seconds 99.9999% (“six 9s”) 31.5 seconds 2.59 seconds 0.605 seconds * Assume a 30-day month.

Microsoft has made the development of web services very simple for developers who use Visual Studio. Add a web service project and the basic plumbing code is generated! Many developers do not know what goes behind the hood or how to customise the generated WSDL when required. I’ve listed some salient ones that may be of help… Apply [WebService(Namespace = " http://www.johannes.org/webservice/2011/11/03/ ",Name=" ExtendingWebService ", Description=" version 1.0 ")] to the class to get these: < wsdl : definitions targetNamespace = "http://www.johannes.org/webservice/2011/11/03/" > < wsdl : documentation > version 1.0 </ wsdl : documentation > ... < wsdl : service name = "ExtendingWebService" > Apply [WebMethod(Description=" This web service is a typical one ")] to the operation to get this: < wsdl : operation name = "..." > < wsdl : documentation > This web service is a