Server-Side Sorting
Perhaps one of the most straightforward controls to use is the server-side sort control, which RFC 2891 (http://www.ietf.org/rfc/rfc2891.txt) defines. The RFC title "LDAP Control Extension for Server Side Sorting of Search Results" makes this control's purpose obvious. When you perform generic LDAP searches, the results don't come back in any kind of ordered fashion, which might be inconvenient if you want to present the returned data in a front-end interface for users. You could retrieve all the search results, store them in a data structure such as a hash or array, and sort them after the query has been completed. However, this type of sorting isn't efficient for large result sets. The more optimal solution, at least from the client viewpoint, is to have the server sort the search results so that the client can start displaying the entries in a sorted fashion as soon as it receives them.
Listing 1 shows an example of how to use the server-side sort control. The script searches for and prints all user objects in the Global Catalog (GC) that have a last name (sn). This example is contrived, but it illustrates how to use the control, and you can easily adapt the code to perform a useful task in your environment. The code at callout A in Listing 1 contains the module inclusions. Using strict is always a good idea—even in trivial scripts—because you never know when those scripts might turn into something more complex. Three Net::LDAP modules are required to perform the search and use the control. The Net::LDAP::Constant module retrieves the LDAP_CONTROL_SORTREQUEST constant, which contains a unique number that represents the control that the script later passes to the Net::LDAP::Control module. . . .
