i will try to explain: if you create a DCI, u must create Events, Actions and Event Processing Policy items too...
for example: if you created DCI "Check HTTP at myserver.com" you must create at least two Events, one- with Severity "Normal" and another - with Severity "Warning" (like this: HTTP_OK and HTTP_NOK (not OK) ).
Example of HTTP request:
Data
Parameter: ServiceCheck.HTTP(10.10.0.1,80,/test.php,webtest.myserver.com,"^HTTP/1\.[01] 200.*")
Origin: NetXMS Agent
Data Type: Integer
(Info: u must use this regexp for search for NEGATIVE situation! not for POSITIVE!)
This type of request can return 4 statements (u can found it all at Forum by Search):
0 – request saccesfuly complited
1 – bad arguments
2 – unable to connect
3 – bad response (requested at regexp info not found at server's response)
At Trasholds list of DCI u must specify two states:
For Problem found:
equal = 0
event = HTTP_NOK
For Problem resolved:
equal = 3
event = HTTP_OK
Now you can create a Action, called "Send E-mail". You can specify a recipient (it can be a one address or mailing list).
And finally, create 2 Event Processing items: for processing HTTP_OK and HTTP_NOK.
You can found this information at Users manual.
I only try point to path for you...
Hope it help.