7 A Quality-enabled Spatial Integration System
151
P
P’’’
Longitude
P’’
1
0
Spatial cover
Latitude
P’
Accordance rate
Fig. 7.13. A 3D illustration of the quality satisfaction problem between four quality values P,
P
, P
and P
Definition 7.4 (Mapping). A mapping is a couple (E ←− e, κ), where E is an element of the global schema, e is an element or a tuple of elements of the source
schema (identified by their absolute or relative paths), and κ is a quality assertion
describing E.
E is called the target of the mapping, e is its source, and κ is its quality assertion.
The quality assertion κ of the mapping describes the quality of element E as being
corresponding to e. For example, mapping between classes Road and vCommL of
TQe can be expressed as follows:
(Road ←− vCommL, κ vr ),
where κ vr is the quality assertion defined in Sect. 7.6.5.
7.7 Processing Quality-mediated Queries
7.7.1 Quality Query Language
The quality query language is based on GQuery [9], extended by a syntactic sugar
clause Such That to express quality constraints. A query expression is defined as
a block For-Let-Where-Such that followed by a Return clause. We assume that
clause Where contains conditions with only an attribute, an operator (=, <, ≤, ,
etc.), and a constant; it does contain no joins and no attribute comparison. For example, query Q 0 , defined in Sect. 7.6.1, can be written as follows:
151
P
P’’’
Longitude
P’’
1
0
Spatial cover
Latitude
P’
Accordance rate
Fig. 7.13. A 3D illustration of the quality satisfaction problem between four quality values P,
P
, P
and P
Definition 7.4 (Mapping). A mapping is a couple (E ←− e, κ), where E is an element of the global schema, e is an element or a tuple of elements of the source
schema (identified by their absolute or relative paths), and κ is a quality assertion
describing E.
E is called the target of the mapping, e is its source, and κ is its quality assertion.
The quality assertion κ of the mapping describes the quality of element E as being
corresponding to e. For example, mapping between classes Road and vCommL of
TQe can be expressed as follows:
(Road ←− vCommL, κ vr ),
where κ vr is the quality assertion defined in Sect. 7.6.5.
7.7 Processing Quality-mediated Queries
7.7.1 Quality Query Language
The quality query language is based on GQuery [9], extended by a syntactic sugar
clause Such That to express quality constraints. A query expression is defined as
a block For-Let-Where-Such that followed by a Return clause. We assume that
clause Where contains conditions with only an attribute, an operator (=, <, ≤, ,
etc.), and a constant; it does contain no joins and no attribute comparison. For example, query Q 0 , defined in Sect. 7.6.1, can be written as follows: