To call a synchronous App Engine process via PeopleCode, use the CallAppEngine() builtin function. Any run parameters for the App Engine can be passed through a record specified in the function parameters. The record field values are loaded to the App Engine program’s state record(s) when it runs.
If attempting to initiate an App Engine process asynchronously, the only way to do so is through the ProcessRequest class — the PeopleCode API for the Process Scheduler. Unlike CallAppEngine(), there is no straightforward way to pass parameters to the scheduled process. Following are 2 methods for passing parameters to an App Engine process.