How I can decode WebSphere Portal url?
For example this url: /wps/portal/!ut/p/c5/dY7LdoIwAAW_hS9ICEnEZSBaKBSKkUfZcAKtKRYMKo-2X197XHtnObO4oAQ3TnJulRxbfZIdKEBJK2wn24y
Michal's answer is correct, calling the POC servlet that way will decode the state information in the URL and produce an XML representation.
The format of this XML is not published, but is pretty easy to decipher, here's an example of how it can look:
minimized
Home
action
sa.spf_ActionListener
Inspecting the XML allows you to do qualified guesses as to what the different information actually means. The section(s) for example, clearly contains information about the window state and can probably also contain information about portlet mode. The section contains the selection path that the user has traveled, and so on.
Since I don't know what you are planning to use the decoded information for, I can't give you any specific guidelines, but consider the XML representation of the state information internal and do not base any application logic on it, since it can change at any point in time.
It can be useful to decode it for troubleshooting though, and to get a general insight in the URL handling of the Portal.