Many application servers including ASP pages will use a unique session number to identify individuals currently on the site. And while this information doesn't usually contain any historical tracking, it does provides an accurate way of identifying unique sessions.
Session IDs are typically located in either the URL query parameters or in a Cookie that is assigned to the user. As long as this information is logged into the Log File, Urchin can use this to uniquely identify each session. Using Session IDs increases the accuracy of reporting by defeating the effects of proxy servers. Using Session IDs does not provide unique visitor tracking like the UTM system, but if you already have Session IDs in place, it can be an easy way to increase the session accuracy immediately.
Session ID Location
Before configuring Urchin to use Session IDs, check your log file to make sure the IDs are coming through and make a note of the field and format. Session IDs are typically found in the Request (NCSA) field, the URI-Query (W3C), or the Cookie field:
If the ID is found in the URL itself, it will be in the Request field for Apache servers and in the URI Query field for IIS servers. If the ID is found in the Cookie, then it will be in the Cookie field on both systems. Make a note of the field and the variable name used to mark the identifier. If you don't see the ID in the Log File and you are sure you are using Session IDs, check to see that the logging format contains the appropriate field.
Once you have the Session ID information, you can easily set your Profile in Urchin to use this for visitor identification. Bring up the Urchin Administration Interface and under Configuration, click on Edit next to the Profile you wish to configure (or click Add if you don't have the Profile configured yet). Click on the Advanced Tab to bring up the "Visitor Identification" settings:
Shown in the above image, change the Visitor Tracking Method to "Session ID" and set the Session Field to either Request, URI Query, or Cookie as determined above. Then enter what comes before and after the Session ID in the two Parsing boxes. For the first example provided at the beginning of this document, sid=12345&, enter "sid=" and "&" in the two boxes. Click update and you are ready to go.