Building an LDAP Web Service

Okay, now we are ready to create our web service and web methods that call this class and method. Open the code behind on the LDAPWebServ.asmx file. Create a new WebMethod.

[WebMethod] public XmlDocument GetAllUsers() { string filter = "samaccountname=*"; LDAPComLink lcl = new LDAPComLink(); XmlDocument xd = new XmlDocument(); xd = lcl.GetLDAPInfo(filter); return xd; }
As you can see, if you create your class correctly, there isn't much to creating the WebMethod. First we create the filter we want to use. The method we are creating is GetAllUsers. We want to bring back all users on the Directory Server. The filter needed for this step will be dependent on your specific LDAP object. For the Sun One LDAP I used "uid=*". But as you can see, the Active Directory required the filter "samaccountname=*". You have to see your data and then determine at what level to filter.

Then we create an instance of the LDAPComLink object, the class we built earlier. Create an instance of an XmlDocument and then call our GetLDAPInfo method, pass in the filter information and capture the XmlDocument object that is returned. Then the method itself returns the XmlDocument to the caller.

If you don't do anything more than what we have gotten up to this point you should be able to call your method and return the user information from the LDAP server. Set LDAPWebServ.asmx as start page and then run your web service. Choose the link "GetAllUsers" and it should flash up a page with an Invoke button. Click the button and if we did everything right we should see our XML of users and other properties returned from the LDAP application.

To make this web service more robust, you can send the configuration and connectivity information with the filter to the class. You can also add a method for authenticating a user and another method for returning all the groups. All this information is available in the LDAP server, you just need to know how to query it for the right information.

In the code that is provided with this article, I have added additional queries you can send to the Directory server. Hopefully, you will find them useful.

When accessing an LDAP directory server, you need to build a DirectoryEntry and DirectorySearcher objects. Place the results in a SearchResultCollection and then filter on the Collection. To pick out individual pieces from the LDAP, just iterate through the collection pulling out properties and their values.

If you place all the work of querying the LDAP server and the connectivity issues in another class, then the WebMethods from the WebService are simple to create and clutter free. If you have multiple LDAP servers to access, then create a configuration file and get the connectivity information from the configuration file.

This article presented how to access an LDAP directory, the C#.Net way to read the information in the LDAP server and then how to use XmlDocument objects to present them to a Web Service. And finally, how to create the Web Service using the [WebMethod] keyword.

Happy Programming.