2. RELATEDWORK
Many researches in data integration's domain based on me-
diators use the mapping method between mediated schema
and integrated data sources schemas. Two main approaches
are Global As View (GAV) and Local As View (LAV) [9].
Many works have been done in order to integrate data sources
in P2P context where the de¯nition of a unique mediated
schema is unrealistic because of the autonomy and volatility
of peers. In P2P context, Piazza [8] integrates sources that
are semi-structured data based on XML data model and
XQuery language. Peers, interested by exchanging data, es-
tablish semantic links between them. SenPeer [6] is a P2P
system where data sources are expressed using various data
models (e.g. Relational, XML etc.). SenPeer assumes a
super-peer network where peers are connected to super-peers
according to their semantic domains expressed with an on-
tology. Super-peers exchange messages to discover semantic
links between their domains. A query formulated with the
language of a peer is expressed with the query exchange for-
mat SQUEL and sent to its super-peer for execution.