One of my websites is using an external service as an addon for our members which we present inside of a wrapper. They have setup their website so that when one of our members access the page they recognize the member by our unique member ID.

In order for this to work I have to generate a unique URL for each member that includes a number of different items. Here is an example

UpToDate.com/contents/search.do?unid=<unique_id>&srcsys=UTD1316278&eiv=2.1.0&search=<search_phrase>

Each unique url must include:
<unique_id> - The unique identifier is assigned to the specific user. This is what identifies each user uniquely. It must be no more than 32 characters.
<assigned_system_id> - The assigned system id consists of two parts which uniquely identify your site to us.
<protocol_version> - This is 2.1.0.
<search_phrase> - The search phrase is the words entered by the clinician into the search box. This is optional. If you like you can remove the search parameter from the URL or leave it blank.

How do i set this up? I have no idea how to generate this type of URL. I have seen similar URLs generated all the time but i have no idea how do it myself. Do you have any suggestions.