This tutorial covers the MSDK proxy server, a standalone kit executable designed for high-volume online transaction processing, where persistent TCP/IP socket connectivity, load balancing, heartbeat messaging, retrieves, and other critical communication functions are required. Primary and failover proxy instances can run on the same computer as the MSDK core interface or in a distributed model using other computing resources on the network. In all instances, payment transactions flow from the MSDK core interface to the MSDK proxy server to the JPMC payments engine then back.MSDK core interface attributes, like proxy server, IP address, and port number, are entered in the MSDK engine connectivity configuration file with MSDK proxy server origination listening port as well as JPMC payment engine destination IP and port entered in the proxy configuration file. Multiple engine ports can also be configured by defining additional destination elements. The proxy has its own event log-in function as defined in the log-in configuration file. Once all attributes have been properly established, the proxy server can be started.The .NET proxy server starts as a Windows service. This mode can be disabled by using the no service switch. To secure data in transit, transport layer security is available for either or both the MSDK-to-proxy and proxy-to-payment engine communication channels. For sandbox testing, MSDK engine simulators can be used to validate the implementation. Be sure to update configuration files with simulator attributes. Use MSDK Director and kit documentation for additional guidance.