COM/DCOM Connection. A COM/DCOM connection enables client access using the native Windows Component Object Model (COM) or Distributed Component Object Model (DCOM). In a client-server environment, DCOM must be enabled on both the client machine and the machine where the server runs.
IOM Bridge Connection. An IOM Bridge connection enables client access using the SAS Integration Technologies IOM Bridge for COM or IOM Bridge for Java. The IOM Bridge for COM allows you to develop native COM/DCOM applications that access server data on UNIX, VMS, or z/OS. The IOM Bridge for Java allows you to develop applications using Java that access server data on Windows, UNIX, VMS, or z/OS platforms.

To understand how clients connect to servers using COM/DCOM and IOM Bridge connections, see Connecting Clients to IOM Servers in the SAS Integration Technologies: Technical Overview.

The following table shows the supported connection types for each of the four types of IOM servers.

Supported Connection Types
IOM Server Type	COM Connection	IOM Bridge Connection	Both COM and IOM Bridge Connection
SAS Workspace Server	`x`	`x`
SAS Stored Process Server		`x`
SAS OLAP Server	`x`	`x`	`x`
SAS Metadata Server	`x` (experimental only)	`x`	`x` (experimental only)

When to Use a COM/DCOM Connection

For SAS Workspace Servers, SAS OLAP Servers, and SAS Metadata Servers (experimental only), you can use a COM/DCOM server configuration in either of the following situations:

The server will run on a Windows machine and will be accessed by Windows client applications running on remote machines. In this situation, the connection uses DCOM.
The server will run on a Windows machine and will be accessed by Windows client applications running on the same machine. In this situation, the connection uses COM.

If the object server will be accessed by a Java client, you must use an IOM Bridge connection instead.

For more information about COM/DCOM distributed clients, refer to Connecting Clients to IOM Servers in the SAS Integration Technologies: Technical Overview.

When to Use an IOM Bridge Connection

For any IOM server (SAS Workspace Servers, SAS Stored Process Servers, SAS OLAP Servers, and SAS Metadata Servers), you must use an IOM Bridge connection if any of the following are true:

The server will run on a UNIX, VMS, or z/OS machine.
The server will be accessed by Java client applications.
You want to use load balancing to balance work across server processes on the same or separate machines.

You can also use an IOM Bridge connection if the server will run on a Windows machine and will be accessed by Windows clients. In this situation, clients will connect to the server using the IOM Bridge connection instead of a COM/DCOM connection.

For more information about the IOM Bridge for COM and the IOM Bridge for Java, refer to Connecting Clients to IOM Servers in the SAS Integration Technologies: Technical Overview.

When to Use Both IOM Bridge and COM/DCOM Connections

For SAS OLAP Servers and SAS Metadata Servers (where COM server connections are experimental only), you can set up a multi-user server to run IOM Bridge and COM/DCOM connections simultaneously if the server runs on Windows.

When you run the IOM Bridge and COM/DCOM connections simultaneously, you enable both of the following:

single-signon capabilities of the Windows network environment for COM clients and Windows SAS clients
support for Java and for UNIX, VMS, and z/OS SAS clients