A short LDAP Operations tutorial

The extended LDAP sampler was built to support testing for very complex testpurposes. It was aimed at supporting the LDAP operations as close as possible. In this short tutorial, I will explain which LDAP operations exist and what they do. Per operation, I will shortly explain how these operations are implemented.
LDAP servers are some kind of hierarchical database, they store objects (entries) in a tree. The uppermost part of a tree is called the ROOT of the tree.
eg. When a tree starts with dc=com, the root equals dc=com.
The next level can exist under the root, eg dc=test. The full name of this object (the "distinguished name") is "dc=test,dc=com.
Again, a following level can be made, by adding the user "cn=admin" under dc=test,dc=com. This object has a DN (distinguished name) of "cn=admin,dc=test,dc=com".
The relative distinguished name (RDN) is the last part of the DN, eg. cn=admin.
The characteristics of an object are determined by the objectClasses, which can be seen as a collection of attributes.
The type of an object is determined by the "structural objectClass" eg person, organizationalUnit or country.
The attributes contain the data of an object, eg mailaddress, name, streetaddress etc. Each attribute can have 0, 1 or more values.

1 Bind operation

Any contact with an LDAP server MUST start with a bind request. LDAP is a state dependent protocol. Without opening a session to a LDAP server, no additional request can be made. Due to some peculiarities in the JAVA libraries, 2 different bind operations are implemented.

1.1 Thread Bind

This bind is meant to open a session to a LDAP server. Any testplan should use this operation as the starting point from a session. For each Thread (each virtual user) a separate connection with the LDAP server is build, and so a separate Thread bind is performed.

1.2 Single bind/unbind

This bind is used for user authentication verification. A proper developed LDAP client, who needs an authenticated user, perform a bind with a given distinguished name and password. This Single bind/unbind operation is for this purpose. It builds it own separate connection to the LDAP server, performs a bind operation, and ends the connection again (by sending an unbind).

2 Unbind

To close a connection to a LDAP server, an unbind operation is needed. As the Single bind/unbind operation already (implicitly) performs an unbind, only a Thread unbind operation is needed. This Thread unbind just closes the connection and cleans up any resources it has used.

3 Compare

The compare operation needs the full distinguished name from a LDAP object, as well as a attribute and a value for the attribute. It will simply check: "Has this object really this attribute with this value?". Typical use is checking the membership of a certain user with a given group.

The search test simply searches for all objects which comply with a given search filter, e.g. all persons with a "employeeType=inactive" or "all persons with a userID equals user1"

5 Add

This simply add an object to the LDAP directory. Off course the combination of attributes and distinguishedName must be valid!

6 Modify

This operation modifies one or more attributes from a given object. It needs the distinguished name from the object, as well as the attributes and the new values for this attribute.
Three versions are available, add, for adding an attribute value
replace, for overwriting the old attribute value with a new value
delete, to delete a value form an attribute, or to delete all the values of an attribute

7 Delete

This operation deletes an object from the LDAP server. It needs the distinguished name from the object.

8 modDN

This operation modifies the distinguished name from an object (it "moves" the object).
It comes in two flavours, just renaming an entry, then you specify a new RDN (relative distinguished name, this is the lowest part of the DN)
e.g. you can rename "cn=admin,dc=test,dc=com" to cn=administrator,dc=test,dc=com"
The second flavour is renaming (moving) a complete subtree by specifying a "new superior"
e.g. you can move a complete subtree "ou=retired,ou=people,dc=test,dc=com" to a new subtree "ou=retired people,dc=test,dc=com" by specifying a new rdn "ou=retired people" and a new superior of "dc=test,dc=com"