Added examples of subscription with email notification . (#431)

* Documentation now has examples of subscriptions with email notification

Author: durga-vasaadi

wiki/subscription-with-email-notification.md

@@ -36,13 +36,40 @@ subject which is configured in Eiffel Intelligence application.properties. Not r
 If any authentication is needed by Eiffel Intelligence to send the notification email.
 
 ## notificationMessageKeyValues
-Content of the email message. The form key should always be an empty string 
-for email messages. Only one key/value pair is allowed for email message body, 
-since only the first value will be used. 
 
-The form value will be run through JMESPath engine so it is possible to use 
-JMESPath expressions to extract content from the aggregated object. The 
-form value can only be one JSON object.
+Below are the limitations of notificationMessageKeyValues.
+
+### Limitations
+
+* The form key should always be an empty string.
+* The content should be in JSON format.
+* The form value can only be one JSON object is allowed (not several objects on the same level).
+* Only one key/value pair is allowed (since only the first value will be used).
+* It is possible to make use of the data inside the aggregation, using the "@" symbol.
+* As with the conditions, it is also possible to write JMESPath expressions.
+
+In the below example the full aggregation can be sent using the '@' character.
+
+    "notificationMessageKeyValues": [
+        {
+            "formkey": "",
+            "formvalue": "@"
+        }
+    ]
+
+To access parts of the aggregation it is possible to define like the below example:
+
+    "notificationMessageKeyValues": [{
+        "formkey": "",
+        "formvalue": "{parameters: [{ name: 'jsonparams', value : to_string(@) }, { name: 'artifactIdentity', value : @.identity }]}"
+    }]
+
+The key is 'jsonparams' and the value is the full aggregated object. The second parameter is the artifact identity which is extracted from the aggregation, These are part of the notification message for this particular subscription. Below is a list of the parameters defined in the above notification message which will be sent for the subscription.
+
+    parameters:
+        jsonparams: //full aggregated object
+        artifactIdentity: //extract the identity string from the aggregation
+
 
 ## requirements
 An array of one or several requirements. At least one requirement should be 
@@ -83,6 +110,78 @@ be fulfilled.
         ]
     }
 
+Additional examples of how to write subscription with email notification:
+
+The below subscription to trigger a notification an aggregation should contain an artifact with a given identity.
+
+    {
+        "subscriptionName" : "Subscription_with_Mail_Notification",
+        "ldapUserName" : "ABC",
+        "repeat" : false,
+        "created" : 1580287633704,
+
+        "notificationType" : "MAIL",
+        "notificationMeta" : "mymail@company.com, another@email.com",
+        "emailSubject" : "My Email Subject",
+
+        "authenticationType" : "NO_AUTH",
+
+        "notificationMessageKeyValues" : [
+            {
+                "formkey" : "",
+                "formvalue" : "{parameters: [{ name: 'artifactIdentity', value : to_string(@.identity) }, { name: 'testCase', value: to_string(@.testCaseExecutions[0].testCase.id) }]}"
+            }
+        ],
+        "requirements" : [
+            {
+                "conditions" : [
+                    {
+                        "jmespath" : "identity=='pkg:maven/com.othercompany.library/artifact-name@1.0.0'"
+                    }
+                ]
+            }
+        ]
+    }
+
+The JMESPath expression in the subscription notification selects the field identity from the aggregated object and this is used as value for the parameter "artifactIdentity". The second parameter is also extracted from the aggregation and results in a string value of the testcase id. The complete notification message can be seen below:
+
+    parameters:
+        artifactIdentity: //extract the identity string from the aggregation
+        testCase: //extract the testCaseId string from the aggregation
+
+The below subscription will perform a MAIL notification when an artifact identity should contain a given artifact namespace.
+
+    {
+        "subscriptionName" : "Subscription_with_Mail_Notification",
+        "ldapUserName" : "ABC",
+        "repeat" : false,
+        "created" : 1580287633708,
+
+        "notificationType" : "MAIL",
+        "notificationMeta" : "mymail@company.com, another@email.com",
+        "emailSubject" : "My Email Subject",
+
+        "authenticationType" : "NO_AUTH",
+
+        "notificationMessageKeyValues" : [
+            {
+                "formkey" : "",
+                "formvalue" : "@"
+            }
+        ],
+        "requirements" : [
+            {
+                "conditions" : [
+                    {
+                        "jmespath" : "split(identity, '/') | [1] =='com.othercompany.library'"
+                    }
+                ]
+            }
+        ]
+    }
+
+The above example mail notififcation message is the full aggregated object.
+
 ## Enabling E-mail Notification for Eiffel Intelligence
 
 In order to use subscriptions with e-mail notifications, Eiffel Intelligence