FileDocCategorySizeDatePackage
PagedResultsControl.javaAPI DocJava SE 5 API6610Fri Aug 26 14:57:40 BST 2005javax.naming.ldap

PagedResultsControl

public final class PagedResultsControl extends BasicControl
Requests that the results of a search operation be returned by the LDAP server in batches of a specified size. The requestor controls the rate at which batches are returned by the rate at which it invokes search operations.

The following code sample shows how the class may be used:


// Open an LDAP association
LdapContext ctx = new InitialLdapContext();

// Activate paged results
int pageSize = 20; // 20 entries per page
byte[] cookie = null;
int total;
ctx.setRequestControls(new Control[]{
new PagedResultsControl(pageSize, Control.CRITICAL) });

do {
// Perform the search
NamingEnumeration results =
ctx.search("", "(objectclass=*)", new SearchControls());

// Iterate over a batch of search results
while (results != null && results.hasMore()) {
// Display an entry
SearchResult entry = (SearchResult)results.next();
System.out.println(entry.getName());
System.out.println(entry.getAttributes());

// 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) });
} while (cookie != null);

// Close the LDAP association
ctx.close();
...

This class implements the LDAPv3 Control for paged-results as defined in RFC 2696. The control's value has the following ASN.1 definition:


realSearchControlValue ::= SEQUENCE {
size INTEGER (0..maxInt),
-- requested page size from client
-- result set size estimate from server
cookie OCTET STRING
}

since
1.5
see
PagedResultsResponseControl
author
Vincent Ryan

Fields Summary
public static final String
OID
The paged-results control's assigned object identifier is 1.2.840.113556.1.4.319.
private static final byte[]
EMPTY_COOKIE
private static final long
serialVersionUID
Constructors Summary
public PagedResultsControl(int pageSize, boolean criticality)
Constructs a control to set the number of entries to be returned per page of results.

param
pageSize The number of entries to return in a page.
param
criticality If true then the server must honor the control and return search results as indicated by pageSize or refuse to perform the search. If false, then the server need not honor the control.
exception
IOException If an error was encountered while encoding the supplied arguments into a control.


                     		         		                                                                                                                                          	                                          
        
	      

	super(OID, criticality, null);
	value = setEncodedValue(pageSize, EMPTY_COOKIE);
    
public PagedResultsControl(int pageSize, byte[] cookie, boolean criticality)
Constructs a control to set the number of entries to be returned per page of results. The cookie is provided by the server and may be obtained from the paged-results response control.

A sequence of paged-results can be abandoned by setting the pageSize to zero and setting the cookie to the last cookie received from the server.

param
pageSize The number of entries to return in a page.
param
cookie A possibly null server-generated cookie.
param
criticality If true then the server must honor the control and return search results as indicated by pageSize or refuse to perform the search. If false, then the server need not honor the control.
exception
IOException If an error was encountered while encoding the supplied arguments into a control.


	super(OID, criticality, null);
	if (cookie == null) {
	    cookie = EMPTY_COOKIE;
	}
	value = setEncodedValue(pageSize, cookie);
    
Methods Summary
private byte[]setEncodedValue(int pageSize, byte[] cookie)


	// build the ASN.1 encoding
	BerEncoder ber = new BerEncoder(10 + cookie.length);

	ber.beginSeq(Ber.ASN_SEQUENCE | Ber.ASN_CONSTRUCTOR);
	    ber.encodeInt(pageSize);
            ber.encodeOctetString(cookie, Ber.ASN_OCTET_STR);
	ber.endSeq();

	return ber.getTrimmedBuf();