This is a text description of Figure 1E1, "The Gateway Architecture".
This illustration of the gateway architecture is adequately described in the "Architecture" section of the chapter, which is presented before the figure.
The Client is shown connecting to an Oracle integrating server by means of Oracle Net or by means of a local connection.
The Oracle integrating server connects to either of two gateway instances (Oracle Transparent Gateway for DRDA) by means of Oracle Net or by means of local connections (or by one of each - any combination is possible).
One of the gateway instances is linked through SNA to a DRDA Server. The other gateway instance is linked through TCP/IP to a DRDA Server.
The purpose of this figure is to show that the Oracle Transparent Gateway for DRDA can connect an Oracle Database to a non-Oracle database through an Oracle integrating server and a DRDA Server. Connection options include Oracle Net, local connections, SNA links, and TCP/IP links.