Modern directory servers like OpenDJ can handle a high load of write requests, replicating changes quickly both on the LAN and over the WAN.
For a complete example corresponding to the excerpts shown below, see ShortLife.java, one of the OpenDJ LDAP SDK examples.
The four basic CRUD operations — create, read, update, and delete — correspond to the LDAP operations add, search, modify (or modify DN), and delete.[8]
An add request is used to create a new entry in an LDAP directory. The entry must have a unique distinguished name that belongs under a base DN served by the directory. The entry must have a list of attributes that are valid according to the directory schema.
Search requests are described in the chapter on Searching & Comparing Directory Data.
A modify request is used to add, delete, or replace attribute values on an entry in an LDAP directory. The resulting entry must be valid according to the directory schema.
A modify DN request is used to rename or move a directory entry.
In both cases the distinguished name changes. Renaming involves changing
the relative distinguished name, for example from
cn=Bob,ou=People,dc=example,dc=com
to
cn=Ted,ou=People,dc=example,dc=com
. Moving
involves changing the container where the entry is found, for example from
cn=Barbara Jensen,ou=People,dc=Old Company,dc=com
to
cn=Barbara Jensen,ou=People,dc=New Company,dc=com
.
Although they are both considered modify DN operations, renaming a leaf entry is generally much simpler than moving a container entry that has child entries. Not all modify DN operations mobilize equivalent resources on the directory server.
A delete request is used to remove an entry from an LDAP directory.
Directory servers can restrict deletes to leaf entries, so that you
cannot remove an entry that has other child entries. For example, you have
to delete uid=bjensen,ou=People,dc=example,dc=com
and
other peer entries before you delete
ou=People,dc=example,dc=com
unless you send a subtree
delete request control.
As a rule, your client application must be authorized to create, update, and delete directory data. Therefore to prepare to change directory data, you first get a connection, and then bind on that connection as a user who is authorized to make the changes you plan to request.
The Connection.add()
methods let you provide the
entry to add as an AddRequest
, an Entry
,
or as LDIF. If the changes to make are already expressed in LDIF, then
you can also use ChangeRecordReader
s,
ChangeRecord
s, and ChangeRecordWriter
s
to handle the changes.
The following excerpt demonstrates how to add a simple user entry under
ou=People,dc=example,dc=com
.
// An entry to add to the directory Entry entry = new LinkedHashMapEntry("cn=Bob,ou=People,dc=example,dc=com") .addAttribute("cn", "Bob") .addAttribute("objectclass", "top") .addAttribute("objectclass", "person") .addAttribute("objectclass", "organizationalPerson") .addAttribute("objectclass", "inetOrgPerson") .addAttribute("mail", "subgenius@example.com") .addAttribute("sn", "Dobbs"); final LDAPConnectionFactory factory = new LDAPConnectionFactory(host, port); Connection connection = null; try { connection = factory.getConnection(); // Bind as a user who has the right to add entries. connection.bind(adminDN, adminPwd); connection.add(entry); } catch (final ErrorResultException e) { System.err.println(e.getMessage()); System.exit(e.getResult().getResultCode().intValue()); return; } finally { if (connection != null) { connection.close(); } }
The Connection.modify()
methods let you add, replace,
and delete attributes values on an entry. Either the modifications are
expressed in LDIF, or you build a ModifyRequest
to
express the changes.
The following excerpt demonstrates how to replace one attribute value and to add another.
final LDAPConnectionFactory factory = new LDAPConnectionFactory(host, port); Connection connection = null; try { connection = factory.getConnection(); // Bind as a user who has the right to modify entries. connection.bind(adminDN, adminPwd); // Here, entry is a user entry with DN cn=Bob,ou=People,dc=example,dc=com. Entry old = TreeMapEntry.deepCopyOfEntry(entry); entry = entry.replaceAttribute("mail", "spammer@example.com") .addAttribute("description", "I see the fnords."); ModifyRequest request = Entries.diffEntries(old, entry); connection.modify(request); } catch (final ErrorResultException e) { System.err.println(e.getMessage()); System.exit(e.getResult().getResultCode().intValue()); return; } finally { if (connection != null) { connection.close(); } }
The Connection.modifyDN()
methods serve to rename
entries and to move them around.
The following excerpt demonstrates how to rename an entry.
final LDAPConnectionFactory factory = new LDAPConnectionFactory(host, port); Connection connection = null; try { connection = factory.getConnection(); // Bind as a user who has the right to rename entries. connection.bind(adminDN, adminPwd); // Here, entryDN contains cn=Bob,ou=People,dc=example,dc=com. // The second argument is the new relative distinguished name. connection.modifyDN(entryDN, "cn=Ted"); } catch (final ErrorResultException e) { System.err.println(e.getMessage()); System.exit(e.getResult().getResultCode().intValue()); return; } finally { if (connection != null) { connection.close(); } }
If you must move rather than rename entries, have a look at the methods
for ModifyDNRequest
. You can get a new request by using
Requests
static methods.
The following excerpt demonstrates how to delete an entry with DN
cn=Ted,ou=People,dc=example,dc=com
.
final LDAPConnectionFactory factory = new LDAPConnectionFactory(host, port); Connection connection = null; try { connection = factory.getConnection(); // Bind as a user who has the right to delete entries. connection.bind(adminDN, adminPwd); connection.delete("cn=Ted,ou=People,dc=example,dc=com"); } catch (final ErrorResultException e) { System.err.println(e.getMessage()); System.exit(e.getResult().getResultCode().intValue()); return; } finally { if (connection != null) { connection.close(); } }
If you must delete an entire branch of entries instead of a single
leaf entry, build a DeleteRequest
that includes the
SubtreeDeleteRequestControl
, as described in the
section, Subtree Delete
Request Control.
Static groups enumerate user entries. Static groups can grow large. For an example, see the group entry at the end of big-group.ldif:
dn: cn=Static,ou=Groups,dc=example,dc=com objectClass: top objectClass: groupofnames cn: Static member: uid=user.0,ou=People,dc=example,dc=com member: uid=user.1,ou=People,dc=example,dc=com member: uid=user.2,ou=People,dc=example,dc=com ... member: uid=user.10000,ou=People,dc=example,dc=com
To update a static group, you either add members or remove members. For sample code, see UpdateGroup.java, one of the OpenDJ LDAP SDK examples.
The UpdateGroup
example checks that the directory
server supports the Permissive Modify control. With directory servers such
as OpenDJ that support the LDAP Permissive Modify control, you can use the
control to avoid having to determine whether a given member is already in the
group before performing the operation. Instead you can simply request an
add or a delete modification for the member.
final LDAPConnectionFactory factory = new LDAPConnectionFactory(host, port); Connection connection = null; try { connection = factory.getConnection(); Collection<String> controls = RootDSE.readRootDSE(connection).getSupportedControls(); final String user = "cn=Directory Manager"; final char[] password = "password".toCharArray(); connection.bind(user, password); if (controls.contains(PermissiveModifyRequestControl.OID)) { final ModifyRequest request = Requests.newModifyRequest(groupDN) .addControl(PermissiveModifyRequestControl.newControl(true)) .addModification(modType, "member", memberDN); connection.modify(request); } else { /* ... */ } String op = (modType == ModificationType.ADD) ? "added to" : "deleted from"; System.out.println("The entry with DN " + memberDN + " has been " + op + " the group with DN " + groupDN + "."); } catch (final ErrorResultException e) { System.err.println(e.getMessage()); System.exit(e.getResult().getResultCode().intValue()); return; } finally { if (connection != null) { connection.close(); } }
If the directory server does not support the Permissive Modify control, then the example checks whether the member is present in the group by using an LDAP compare operation. If a member to be added does not yet belong to the group, the example requests an add modification. If a member to be deleted does belong to the group, the example requests a delete modification.
final LDAPConnectionFactory factory = new LDAPConnectionFactory(host, port); Connection connection = null; try { connection = factory.getConnection(); Collection<String> controls = RootDSE.readRootDSE(connection).getSupportedControls(); final String user = "cn=Directory Manager"; final char[] password = "password".toCharArray(); connection.bind(user, password); if (controls.contains(PermissiveModifyRequestControl.OID)) { /* ... */ } else { System.out.println("Checking whether the entry with DN " + memberDN + " belongs to the group with DN " + groupDN + "..."); final CompareRequest request = Requests.newCompareRequest(groupDN, "member", memberDN); CompareResult result = connection.compare(request); if (modType == ModificationType.ADD) { if (result.getResultCode() == ResultCode.COMPARE_FALSE) { System.out.println("Member does not yet belong to group." + " Adding it..."); final ModifyRequest addMember = Requests.newModifyRequest(groupDN) .addModification(modType, "member", memberDN); connection.modify(addMember); } } if (modType == ModificationType.DELETE) { if (result.getResultCode() == ResultCode.COMPARE_TRUE) { System.out.println("Member belongs to group." + " Removing it..."); final ModifyRequest delMember = Requests.newModifyRequest(groupDN) .addModification(modType, "member", memberDN); connection.modify(delMember); } } } String op = (modType == ModificationType.ADD) ? "added to" : "deleted from"; System.out.println("The entry with DN " + memberDN + " has been " + op + " the group with DN " + groupDN + "."); } catch (final ErrorResultException e) { System.err.println(e.getMessage()); System.exit(e.getResult().getResultCode().intValue()); return; } finally { if (connection != null) { connection.close(); } }
You can change multiple member values with a single modification. The
final argument of this form of the
ModifyRequest.addModification()
method takes a series
of one or more values. So if you have multiple group members to add or
delete, you can loop over your list to perform compare individual compare
requests, then construct a single modify request to add or delete the
group members. In other words, if you have three members to add, you can
list the three member DNs as arguments of
addModification
.
String member1 = "uid=user1,ou=people,dc=example,dc=com"; String member2 = "uid=user1,ou=people,dc=example,dc=com"; String member3 = "uid=user1,ou=people,dc=example,dc=com"; final ModifyRequest addMember = Requests.newModifyRequest(groupDN) .addModification(modType, "member", member1, member2, member3); connection.modify(addMember);
To try the example, download and import
big-group.ldif
into your directory server, and then
run the sample. For example, if OpenDJ is set up to with directory manager
as cn=Directory Manager
, password
password
listening on localhost
port
1389
, and you run the example with arguments
localhost 1389 cn=Static,ou=Groups,dc=example,dc=com
uid=user.5150,ou=People,dc=example,dc=com del
, the resulting output
is The entry with DN uid=user.5150,ou=People,dc=example,dc=com has
been deleted from the group with DN
cn=Static,ou=Groups,dc=example,dc=com.
.
[8] The LDAP bind operation can potentially result in an update. Some directory servers can be configured to write time stamps in order to track successful or failed binds for password policy reasons.