Merge pull request MicrosoftDocs#23 from eternovsky/master

adding SLA example

Author: noakup

application-insights/custom-SLA-and-breaches.md

@@ -0,0 +1,18 @@
+## Defining a custom SLA, and adherence to it
+#### #count #render #timechart #summarize
+<!-- article_id: 3107‎2017‏‎03827004 -->
+
+The following query defines a custom Service Level Agreement (SLA): a request is considered as meeting SLA if it completes in under 3 seconds. The query then adds a static SLA target of 99.9% of requests needing to meet the SLA. The two are plotted on a time chart. 
+
+```AIQL
+requests
+| where timestamp > ago(7d)
+| summarize slaMet = count(duration < 3000), slaBreached = count(duration >= 3000), totalCount = count() by bin(timestamp, 1h)
+| extend SLAIndex = slaMet * 100.0 / totalCount 
+| extend SLA = 99.9
+| project SLAIndex, timestamp, SLA 
+| render timechart 
+```
+
+The output will look like this:
+<p><img src="~/examples/images/SLA.png" alt="a custom SLA metric definition and its trend over time compared to SLA target"></p>