The trick is this:
If the PluginInfo does NOT contain an entry called SceneFile=, then the Worker automatically goes looking for the FIRST auxiliary file in the submission, and assumes it is the scene file. It is true for every plugin, including Maya, 3dsmax etc.
If the PluginInfo DOES contain a SceneFile= entry pointing at a network location, the auxiliary files will still be sent, but none of them will be assumed to be the scene file to render.
When auxiliary files are specified, and when using the deadlinecommand executable, files located on the local computer performing the submission will be copied automatically over to the Job’s sub-folder in the Jobs folder of the Repository (unless configured otherwise via Tools>Configure Repository Options>Job Settings>Auxiliary Files). Of course, if they are on a network path, they will also be copied. When a Worker dequeues a Job to render, it will copy the content of that folder to the local temp folder and will load from there.
However, when using the REST API, local files on the machine making the call will NOT work because the REMOTE machine you are talking to has to perform the submission. So once again you would have to make a copy of the scene file to a network path that is accessible to all computers on the network, esp. the one running the WebService/Pulse/RCS etc. (I assume it is the same machine hosting the Repository/Database, but it does not have to be). After a successful submission, that temp. network copy could be deleted because it would be now part of the Job in the Job’s aux. files folder.
See this post for a similar situation: