This class provide a basic process which is
able to read an XML file
reads a file which coordinates (local path or URL) is give in the
file parameter of the generate call, parse it and generate a SAX event
flow to the next handler
Register a channel with its input
The algorithm depends on the context (transformation or call)
If we are in a Transformation:
the in are input for the channel, they cannot be anything but Channel
the out are output for the channel, they cannot be anything but Channel
If we are in a Call:
the in are output to the channel, they cannot be anything but Channel and _stdin_
the out are input to the channel, they cannot be anything but Channel and _stdout_ or _null_
Register a channel with its output
The algorithm depends on the context (transformation or call)
If we are in a Transformation:
the in are input for the channel, they cannot be anything but Channel
the out are output for the channel, they cannot be anything but Channel
If we are in a Call:
the in are output to the channel, they cannot be anything but Channel and _stdin_
the out are input to the channel, they cannot be anything but Channel and _stdout_ or _null_