This is a feature that will be added in much a broader scope - along with GUI, API and more usage examples - in next releases, but for 1.1, a zato-labs project is provided to support an invoke/retry pattern.
It was always possible to use GUI, API or a service to ping an outgoingHTTP/SOAP connection - the idea behind it is that you pretty much always want to check whether it is your servers that can connect to remote services not that you can access remote resources from your local host as it doesn’t tell you, for instance, if firewalls between the servers and outside world are configured properly.
Did you know that you could invoke any service from command line? This works with both Zato’s own API and the services you develop. Depending on how a service is implemented/what it’s exposed through, it can be done with JSON, plain XML, SOAP or any other data format a service accepts.