The javax.naming.ldap.BasicControl which implements the javax.naming.ldap.Control serves as a base implementation for extending other controls.
The paged results control is useful for LDAP clients which want to receive search results in a controlled manner limited by the page size. The page size can be configured by the client as per the availability of its resources, like bandwidth and the processing capability.
The server uses a cookie (similar to the HTTP session cookie mechanism) to maintain the state of the search requests in order to track the results being sent to the client. The paged results control is specified in RFC 2696. The classes below provide the functionality required to support paged results control.
The example below illustrates the client-server interaction between a client doing a search requesting a page size limit of 5. The entire result set returned by the server contains 21 entries.
// Activate paged results int pageSize = 5; // 5 entries per page byte[] cookie = null; int total; ctx.setRequestControls(new Control[]{ new PagedResultsControl(pageSize, Control.CRITICAL) }); // Perform the search NamingEnumeration results = ctx.search("", "(objectclass=*)", new SearchControls());
// Iterate over a batch of search results sent by the server while (results != null && results.hasMore()) { // Display an entry SearchResult entry = (SearchResult)results.next(); System.out.println(entry.getName()); // Handle the entry's response controls (if any) if (entry instanceof HasControls) { // ((HasControls)entry).getControls(); } } // Examine the paged results control response Control[] controls = ctx.getResponseControls(); if (controls != null) { for (int i = 0; i < controls.length; i++) { if (controls[i] instanceof PagedResultsResponseControl) { PagedResultsResponseControl prrc = (PagedResultsResponseControl)controls[i]; total = prrc.getResultSize(); cookie = prrc.getCookie(); } else { // Handle other response controls (if any) } } }
// Re-activate paged results ctx.setRequestControls(new Control[]{ new PagedResultsControl(pageSize, cookie, Control.CRITICAL) });
The complete JNDI example can be found here.
Note: The Paged Search Control is supported by the Windows Active Directory Server. It's not supported by the Sun Java Directory Server version 5.2