Spawner Overview

The Object Spawner is a program that can run on the server host and listen for requests. You must use a spawner to run SAS Workspace Servers and SAS Stored Process Servers.

Before you can run the spawner, you must create a Metadata Configuration File that contains information for accessing the metadata server. When you invoke the spawner, the spawner works as follows:

1. accesses the metadata configuration file for information about how to connect to the SAS Metadata Server.
2. connects to the SAS Metadata Server for configuration information.

The spawner can then listen for requests for various Spawner Tasks. (For details about starting a spawner, see Invoking (Starting) the Spawner).

Metadata Configuration File

A metadata configuration file contains information for accessing a metadata server. The spawner uses the information contained in the configuration file to connect to a metadata server and read the appropriate server definitions. In order for the spawner to connect to and read the appropriate metadata from a metadata server, you must specify the appropriate login information in the metadata configuration file. For details, see Planning the Spawner Security.

To create the metadata configuration file, see Creating a Metadata Configuration File in SAS.

Spawner Tasks

When a request is received, the spawner accepts the connection and performs the action that is associated with the port or service on which the connection was made. A connection to a spawner can do the following:

• request a server. When a connection is made on a port or service that is associated with a Server object, the spawner authenticates the client connection against the host authentication provider for the server's machine. The spawner then launches a server for use by the connecting client. To launch the server, the spawner locates the associated server definitions on the SAS Metadata Server.

  When you define a server in SAS Management Console, you must specify a command that the spawner will use to start the server. For details about the server command, see Server Startup Command. For SAS Stored Process Servers, on the server definition, you must also configure credentials for the spawner to use to start a multi-user server.

  Every connection to the server is authenticated (against the host authentication provider for the server's machine) with the credentials of the client; depending on the type of server, the process then runs under the following credentials:

  • For SAS Workspace Servers, the credentials of the client.
  • For SAS Stored Process Servers, the multi-user login credentials that are specified in the stored process server definition (Advanced Options Credential in the New Server Wizard) in SAS Management Console.

  To understand the different security considerations for SAS Workspace and SAS Stored Process Servers, see Planning Security on Workspace and Stored Process Servers.

  For a scenario that shows the flow for spawner requests, see Scenario: Security Configuration for Spawner and Load-Balancing.

  You can use normal server security mechanisms to protect sensitive data. For more information about server security, see the Security section.

• initiate the operator interface. When a connection is made on the port or service that is identified as the operator port or operator service in the spawner definition, the spawner initiates the administration interface. Only one administrator can be active at a given time. For more information about the administration interface, see Using Telnet to Administer the Spawner.

• request a Universal Unique Identifier (UUID). A spawner can be configured to support UUID generation; or, it can be configured solely as a UUID generator daemon (UUIDGEND). In either case, when a connection is made on the port or service that is identified as a UUID port or UUID service in the spawner definition, the spawner initiates UUID generation. For more information, see Configuring a UUID Generator.

In addition, for stored process servers, you must configure the spawner for Load Balancing. You can also configure load balancing for SAS Workspace Servers.

Multi-User Server

For stored process servers, you must specify a login on the Credentials tab of the server definition advanced options. The spawner that is associated with the server invokes a multiple user server that runs under this login. Other clients of this server definition can then connect to the server that is running.

Note: If you do not specify a multi-user login for the stored process server, the stored process server will not run and a message similar to the following will be displayed:

This server (OMSOBJ:LOGICALSERVER/A5SRQ5Z5.AT00008E)
cannot be spawned without credentials which specify
the server process username

Note: Because the load-balancing stored process server runs under the multi-user login credentials, the operating system account for these credentials must have access to any operating system resources used by stored processes that are hosted on this server.

Load Balancing

You can set up load balancing for workspace servers; you must set up load balancing for stored process servers.

A load balancer routine runs in the spawner and directs client requests to the SAS process (on a server) that is least loaded (busy) at the time the client request is made. Subsequent calls between the client and SAS are then direct calls. The load balancer uses a load-balancing algorithm (cost or response time) to determine which server is least loaded.

When launching a load-balancing spawner, you specify a Metadata Configuration File that contains information for accessing the SAS Metadata Server. The spawner then reads the load-balancing configuration metadata from the SAS Metadata Server and uses the metadata to determine what other machines or ports are in the load-balancing cluster. The spawner attempts to establish an IOM connection to each spawner in the cluster. Additional spawners can be added to a cluster at any time.

For an overview of load balancing, see Load Balancing.