OpenSRS API Integration for XML

Tom Jones
Semantic validity and API implementation
Any API implementation that encodes/decodes OPS messages should be
reflexive. That means that, if a message is encoded and then decoded, the
results of that decoding and the original message should be identical. In
other words:
MSG A := decode (encode (MSG A) )
Alternatively,
let MSG A' := encode (MSG A)
then MSG A := decode (MSG A')
This restriction can be relaxed when it comes to the ordering of array
elements and associative array elements in the OPS message. As long as the
semantic meaning of the elements is preserved (semantic equivalence), the
actual textual ordering in the XML stream is not important.
This is because the XML data structure representation uses element numbers
(in the case of array) and field names (in the case of associative arrays) to
represent the data stream, and this information can be used by the API to
reconstruct the XML representation back into an in-memory data structure.
This approach supports languages in which the ordering of elements for inmemory
data structures is not deterministic., for example, Perl hashes
(associative arrays), where the physical ordering of elements within the hash
is not guaranteed.