A Protocol defines a mechanism for contacting RoboServer. Currently Kapow Katalyst comes with three different protocols, each with its own set of advantages and disadvantages:

SocketContacts RoboServer using a TCP socket. This is a simple, low-level protocol, using XML or Java binary representation depending on the platform. See description of properties below.
Random Distribution Given a list of protocols, each time the client makes a request, one of the protocols will be chosen based on whether it is currently marked as available or not. This provides simple fail-over if at least one of the RoboServers specified in the list is available. While the random distribution protocol does not explicitly provide load balancing, it can be used for that purpose. See description of properties below.


The protocols are configured using the following properties:


Host Name:
The name of the host machine RoboServer is located on.
Port Number:
The port number RoboServer is listening on. The default port number is 50000.

Random Distribution Protocol

Retry If Connection Lost:
Enable this option to support transparent fail-over.

If the connection to a RoboServer is lost while handling a request, the protocol can re-submit the request to another RoboServer from the list. In order for this to work correctly, the robot in question must be idempotent, meaning that repeated invocations of the robot have the same effect as one. Typically this is the case with robots that do not cause permanent changes in the sites they access.
The list of protocols to distribute requests to. The random distribution policy select a protocol at random for handling each individual request.

Depending on what plugins are installed into Kapow Katalyst, other protocols may be available.