PassThrough Transport is a non-blocking HTTP transport implementation based on HTTP Core NIO, and is the default HTTP transport shipped with WSO2 ESB. Although the PassThrough Transport is somewhat similar to the NHTTP transport, it overcomes all the limitations of the NHTTP transport and provides a significant performance gain. The PassThrough Transport also has a simpler and cleaner model for forwarding messages back and forth.
org.apache.synapse.transport.passthru.PassThroughHttpSSLListener is the listener class of the PassThrough Transport, and it receives HTTPS inbound requests.
org.apache.synapse.transport.passthru.PassThroughHttpSSLSender is the sender class of the PassThrough Transport, and it sends out HTTPS outbound requests.
With the PassThrough transport and HTTP NIO transport, you can enable connection throttling to restrict the number of simultaneous open connections. To enable connection throttling, edit the <
ESB_HOME>/repository/conf/nhttp.properties (for the HTTP NIO transport) or
<ESB_HOME>/repository/conf/passthru-http.properties (for the PassThrough transport) and add the following line:
max_open_connections = 2
This will restrict simultaneous open incoming connections to 2. To disable throttling, delete the
max_open_connections setting or set it to -1.
Connection throttling is never exact. For example, setting this property to 2 will result in roughly two simultaneous open connections at any given time.