LDAP directory services versus the Sybase sql.ini file

LDAP directory services are a convenient alternative to the typical Sybase sql.ini file, which stores server information in a “flat” file. As a result, any changes to server information in the sql.ini file need to be updated on each machine (client and server) in the enterprise.

With LDAP directory services, the integration of user, resource, and security information in a centralized repository makes administration of resource information much easier. In addition, LDAP services provide:

• A single, hierarchical view of information, such as users, software, resources, networks, files

• A single sign-on for servers and distributed enterprise applications

• User login and role information for access control to sensitive data

User roles can be assigned to a single individual, such as the system administrator, or to large groups of users, such as accounting department personnel. Roles determine what information and servers users can access, and what, if any, read and write permission they possess. Multiple users with the same user role can be multiplexed to a few server connections, saving resources and increasing scalability.

The traditional sql.ini file specifying a TCP connection and a failover machine looks like this:

[MONEY]

master=TCP, huey, 5000

query=TCP, huey, 5000

hafailover=PERSONEL

[PERSONEL]

master=TCP, huey, 5000

query=TCP, huey, 5000

hafailover=MONEY

An example of an LDAP entry with TCP and a failover machine looks like this:

dn: sybaseServername=foobar, dc=sybase,dc=com
objectClass: sybaseServer
sybaseVersion: 15501
sybaseServername: foobar
sybaseService: ASE
sybaseStatus: 4
sybaseAddress: TCP#1#foobar 5000
sybaseRetryCount: 12
sybaseRetryDelay: 30

sybaseHAServernam: secondary

Sybase provides LDAP directory schema in %SYBASE%\%SYBASE_OCS%\ini for the following LDAP services:

• sybase.schema - it contains the directory schema to be used with OpenLDAP servers.

• sybase-schema.conf - it contains the directory schema but in a Netscape-specific syntax.

• sybase.ldf - it contains directory schema in Unicode format for a Microsoft Active Directory.

In the previous example, the entity describes an Adaptive Server named “foobar” listening on a TCP connection with a port number of 5000. This entity also specifies a retry count of 12 (times) and a retry delay of 30 (seconds). sybaseRetryCount and sybaseRetryDelay map to CS_RETRY_COUNT and CS_LOOP_DELAY, respectively. When Client-Library finds an address where a server responds, the login dialog begins between Client-Library and the server. Client-Library does not retry any other addresses if the login attempt fails.

The most important entity is the address attribute, which contains the information for how to set up a connection to the server and how the server listens for incoming connections. For entries to be usable by different Sybase products on different platforms, the Protocol field and the Address field in an address attribute (for example, “TCP” and “foobar 5000”) should be in a platform and product independent form.