In ArcSDE 9.2, a service can be specified in several ways. By default, the service is named in the SDEHOME/etc/services.sde file. However, you can override the service in the services.sde file in three ways:

• The SDEINSTANCE environment variable can be set to the name of a service.

  setenv SDEINSTANCE esri_sde3
  
  

• The sdemon command "-i <service>" option accepts the service name as its argument.
   
• The sdemon command "-H <sde_directory>" option specifies the home directory (normally one not specified by $SDEHOME) within which the etc/services.sde file contains the service name.

Once giomgr starts, it listens on the port number assigned to the service for ArcSDE client connection requests. When a connection request is received, the giomgr verifies the user and password and spawns a gsrvr process and assigns it a new port number on which to communicate.

Note: Please be sure to read the book "Managing ArcSDE Application Servers" if you have not already done so. You should also read chapter 4 of "Understanding ArcSDE" to understand the configuration choices between using an ArcSDE server (application server) and using direct connections.

The services.sde file

The services.sde file contains the unique instance name and the network port number and protocol on which the giomgr accepts connection requests to the instance. By default, the services.sde file instance name is esri_sde with a 5151 port number using a TCP/IP protocol.

The system services file must contain a service name that matches the instance name in the services.sde file in the etc subdirectory of the ArcSDE home directory. When the connection is started, the system services file is searched for a service name that matches the instance name in the services.sde file. If a match is not found, an error is returned.

The system services file contains many service names, at least one of which must match your ArcSDE instance name. The service name must be entered into the services file on both the ArcSDE server and the client machines. You may use the NIS (Network Information Service) /etc/services file if you are running yellow pages, in which case you don’t have to redundantly update the client and server /etc/services files.

Here is an example from a UNIX /etc/services file that contains two ArcSDE instances:

This defines two instance names: esri_sde and esri_sde2. Each instance has its own home directory with the instance name in the services.sde file.

Clients and services

The service argument of the SE_connection_create function accepts the instance directly unless it is NULL. In that case, it uses the instance defined in the SDEINSTANCE variable. If the SE_connection_create instance argument is NULL and SDEINSTANCE is undefined, the instance name defaults to esri_sde.

Note: The terms instance and service are synonymous. The term instance is a legacy term from SDE 2. The term service is the more current name and is used in concept discussions. However, many functions and ArcSDE administration commands still have references to instance.