streams as input/output

Hi,

While transforming an xml the transformer can take in one stream source and
output to a stream target.For multiple source it is expected to read using
the document(file path) function.Similarly to write out to more than one
output xsl:result-document is used which also writes to a file.

In both cases we need to use a file to read out of or write to.How can we
use input or output streams to do the same instead of a file?

Regards,
Shadab