Undertstanding pzPostData
When working with the Pega Platform you may see URL's contains a parameter name of pzPostData with a numeric value.
Example:
https://xxxxx/prweb/PRServlet/yB7Ch8mVBTECLOyWC9zzsLy8qPpsyGcE*/!STANDARD?pzPostData=-832304156
Why?
The pzPostData value is a pointer to an internal map that contains data from an earlier HTTP POST request that caused a HTTP 303 redirect.
If a HTTP POST was done using: https://xxxxx/prweb/PRServlet the application will send a HTTP 303 redirect so that the AccessGroup Hash is added to the URL and processing can occur in the proper context. To preserve the HTTP POST data we store the data in a map and provide the pzPostData parameter and value so the resulting GET request doesn't have data loss.
HTTP POST to https://xxxxx/prweb/PRServlet
Results in HTTP 303 "See Other" response with location header: https://xxxxx/prweb/PRServlet/yB7Ch8mVBTECLOyWC9zzsLy8qPpsyGcE*/!STANDARD?pzPostData=-832304156
Browser follows the redirect using the location header as a HTTP GET request. We internally use the pzPostData pointer to make sure that the processing occurs with the same data from the original HTTP POST.