Chapter 8. Creating and maintaining database links
Chapter 8. Creating and maintaining database links When a client application requests data from a database link, it retrieves the data from the remote database and returns it to the client. Chaining means that a server contacts other servers on behalf of a client application and then returns the combined results. This chaining process is implemented through a database link. 8.1. Creating a new database link Basic database link configuration requires the following information: Suffix information The suffix information must correspond to the suffix on the remote server that contains the data. You can create suffix in the directory tree managed by the database link. Bind credentials When the database link binds to a remote server, it impersonates a user, and this specifies the DN and the credentials for each database link to use to bind with remote servers. LDAP URL The LDAP URL information provides the LDAP URL of the remote server to which the database link connects. URL consists of the protocol ( LDAP or LADPS ), the host name or IP address ( IPv4 or IPv6 ) for the server, and the port. List of failover servers The list of failover servers is a list of alternative servers for the database link to contact in the case of a failure and is optional. Note If secure binds are required for simple password authentication, using a secure connection ( TLS and STARTTLS connections or the SASL authentication) is recommended when any chaining operations are performed . 8.2. Creating a New Database Link Using the Command Line You can create a new database link by using the dsconf chaining link-create command. Prerequisites You have opened the Directory Server user interface in the web console and selected the instance. Procedure Create a new database link : # dsconf -D "cn=Directory Manager" ldap://server.example.com chaining link-create --suffix="ou=Customers,dc=example,dc=com" --server-url="ldap://remote_server.example.com:389" --bind-mech=SIMPLE --bind-dn="cn=proxy_user,cn=config" --bind-pw="password" "example_chain_name" By using this command, you create the database link named example_chain_name for ou=Customers,dc=example,dc=com which refers to the ldap://remote_server.example.com:389 server and uses the specified bind DN and password to authenticate. You must set bind-mech to SIMPLE ( EXTERNAL for certificate based authentication) or GSSAPI for kerberos authentication. Display additional settings that you can set when you create the database link: # dsconf -D "cn=Directory Manager" ldap://server.example.com chaining link-create --help Note To grant the proxy_user the rights to access data, you must create the proxy ACI entry in the dc=example,dc=com suffix on remote server. Verification Display the new database link: # dsconf -D "cn=Directory Manager" ldap://server.example.com chaining link-create --suffix="ou=Customers,dc=example,dc=com" --server-url="ldap://remote_server.example.com:389" --bind-mech=SIMPLE --bind-dn="cn=proxy_user,cn=config" --bind-pw="password" "example_chain_name" 8.3. Creating a New Database Link Using the Web Console You can create a new database link by using the web console. Prerequisites You have opened the Directory Server user interface in the web console and selected the instance. Procedure Open the Database menu. Create a new suffix: Click Create Suffix button. Enter the DN suffix and back end name. Select Create The Top Suffix Entry and click Create Suffix . Select the suffix, click Suffix Tasks button on the right side, and select Create Database Link . Fill the fields with the details about the connection to the remote server. Click Create Database Link . Verification Open the Database menu and ensure that the new database link appears in this menu. 8.4. Managing the default configuration for new database links You can manage the default configuration of database links by using the dsconf chaining command . Procedure Display the current default values of the database link: Use the dsconf chaining config-set-def command to change the new database links configuration. For example, to set the response-delay parameter to 30 , run: The example command sets the default response timeout for all chaining connections. You can overwrite the response timeout for a specific chaining link by using the dsconf instance chaining link-set command. To see the list of all parameters you can set, run:
dsconf -D "cn=Directory Manager" ldap://server.example.com chaining link-create --suffix="ou=Customers,dc=example,dc=com" --server-url="ldap://remote_server.example.com:389" --bind-mech=SIMPLE --bind-dn="cn=proxy_user,cn=config" --bind-pw="password" "example_chain_name" dsconf -D "cn=Directory Manager" ldap://server.example.com chaining link-create --help dsconf -D "cn=Directory Manager" ldap://server.example.com chaining link-create --suffix="ou=Customers,dc=example,dc=com" --server-url="ldap://remote_server.example.com:389" --bind-mech=SIMPLE --bind-dn="cn=proxy_user,cn=config" --bind-pw="password" "example_chain_name" dsconf -D "cn=Directory Manager" ldap://server.example.com chaining config-get-def dsconf -D "cn=Directory Manager" ldap://server.example.com chaining config-set-def --response-delay 30 dsconf -D "cn=Directory Manager" ldap://server.example.com chaining config-set-def --help