LDAP directory services versus the Sybase interfaces file

The LDAP driver implements directory services for use with an LDAP server. LDAP directories are an infrastructure that provide:

A network-based alternative to the traditional Sybase interfaces file
A single, hierarchical view of information, including users, software, resources, networks, files, and so on

Table 6-1 highlights the differences between the Sybase interfaces file and an LDAP server.

**Table 6-1: interfaces file versus LDAP directory services**
interfaces file	Directory services
Platform-specific	Platform-independent
Specific to each Sybase installation	Centralized and hierarchical
Contains separate master and query entries	One entry for each server that is accessed by both clients and servers
Cannot store metadata about the server	Stores metadata about the server

LDAP directory services support more attributes than the Sybase interfaces file. These attributes can include server version, server status, and so on. See Table 6-2 for a list of attributes.

LDAP is only supported with reentrant libraries. You must use isql_r, instead of isql, when connecting to a server using LDAP directory services.

Table 6-2 lists the Sybase LDAP directory entries.

**Table 6-2: Sybase LDAP directory definitions**
Attribute name	Value type	Description
ditbase	interfaces file or libtcl.cfg*	DIT base for object tree. If the libtcl.cfg* file is specified, the interfaces file is ignored. The libtcl.cfg* file can be overridden with ct_con_prop() for a specified connection.
dn	Character string	Distinguished name. Must be unique name that identifies the object.
sybaseVersion	Integer	Server version number.
sybaseServername	Character string	Server name.
sybaseService	Character string	Service type: Sybase Adaptive Server, or Sybase SQL Server.
sybaseStatus	Integer	Status: 1 – Active, 2 – Stopped, 3 – Failed, 4 – Unknown.
sybaseAddress	String	Each server address includes: Protocol: TCP, NAMEPIPE, SPX DECNET (entry is case-sensitive). Address: any valid address for the protocol type. dscp splits this attribute into Transport type and Transport address.
sybaseSecurity (optional)	String	Security OID (object ID).
sybaseRetryCount	Integer	This attribute is mapped to CS_RETRY_COUNT, which specifies the number of times that ct_connect retries the sequence of network addresses associated with a server name.
sybaseRetryDelay	Integer	This attribute is mapped to CS_LOOP_DELAY, which specifies the delay, in seconds, that ct_connect waits before retrying the entire sequence of addresses.
sybaseHAservername (optional)	String	A secondary server for failover protection.

The traditional interfaces file on a UNIX machine with TCP connection and a failover machine looks like:

master tcp ether huey 5000

query tcp ether huey 5000

hafailover secondary

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

dn: sybaseServername=foobar, dc=sybase,dc=com
objectClass: sybaseServer
sybaseVersion: 12500
sybaseServername: foobar
sybaseService: ASE
sybaseStatus: 4
sybaseAddress: TCP#1#foobar 5000
sybaseRetryCount: 12
sybaseRetryDelay: 30

sybaseHAServernam: secondary

All entries in the LDAP directory service are called entities. Each entity has a distinguished name (DN) and is stored in a hierarchical tree structure based on its DN. This tree is call the directory information tree (DIT). Client applications use a DIT base to specify where entities are stored. See “The libtcl.cfg and libtcl64.cfg files”.

In the example above, the entry 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). Once a client has found an address where a server responds, the login dialog between the client and the server begins.

You can find a complete list of Sybase’s LDAP directory schema in $SYBASE/$SYBASE_OCS/config

In the same directory, there is also a file called sybase-schema.conf, which contains the same schema, but uses a Netscape-specific syntax.

Since LDAP supports multiple entries for each attribute, each address attribute must contain the address of a single server, including protocol, access type, and address. See sybaseAddress in Table 6-2.

For example, this is an LDAP entry for an NT server listening on two addresses, with different connection protocols:

sybaseAddress = TCP#1#TOEJAM 4444

sybaseAddress = NAMEPIPE#1#\pipe\sybase\query

Each entry in the address field is separated by the # character.

You can edit these entries with the dscp or dsedit utility. See “Adding a server to the directory services”.

To ensure cross-platform compatibility for all Sybase products, the protocol and address attribute fields should be in a platform- and product-independent format.