Tiêu chuẩn quốc tế

• Số hiệu / Standard Number: ANSI INCITS/ISO 19143:2011
• Năm ban hành / Publication date: 2011
• Tình trạng / Status: A - Còn hiệu lực
• Tên tiếng Anh / Title in English: Geographic information - Filter encoding
• Số trang / Page: 90

Phạm vi áp dụng / Scope of standard

This International Standard describes an XML and KVP encoding of
a system neutral syntax for expressing projections, selection and
sorting clauses collectively called a query expression.

These components are modular and intended to be used together or
individually by other standards which reference this International
Standard.

EXAMPLE 1 ISO 19142 makes use of some or all of these
components.

This International Standard defines an abstract component, named
AbstractQueryExpression, from which other specifications can
subclass concrete query elements to implement query operations.

This International Standard also defines an additional abstract
query component, named AbstractAdhocQueryExpresison, which is
derived from AbstractQueryExpression and from which other
specifications can subclass concrete query elements which follow
the following query pattern:

An abstract query element from which service specifications can
subclass a concrete query element that implements a query operation
that allows a client to specify a list of resource types, an
optional projection clause, an optional selection clause, and an
optional sorting clause to query a subset of resources that satisfy
the selection clause.

This pattern is referred to as an ad hoc query pattern since the
server is not aware of the query until it is submitted for
processing. This is in contrast to a stored query expression, which
is stored and can be invoked by name or identifier.

This International Standard also describes an XML and KVP
encoding of a system-neutral representation of a select clause. The
XML representation is easily validated, parsed and transformed into
a server-specific language required to retrieve or modify object
instances stored in some persistent object store.

EXAMPLE 2 An XML encoded filter can be transformed into a WHERE
clause for a SQL SELECT statement to fetch data stored in a
SQL-based relational database. Similarly, and XML encoded filter
expression can be transformed into an XPath or XPointer expression
for fetching data from XML documents.

This International Standard defines the XML encoding for the
following predicates.

a) A standard set of logical predicates: and, or and not.

b) A standard set of comparison predicates: equal to, not equal
to, less than, less than or equal to, greater than, greater than or
equal to, like, is null and between.

c) A standard set of spatial predicates: equal, disjoint,
touches, within, overlaps, crosses, intersects, contains, within a
specified distance, beyond a specified distance and BBOX.

d) A standard set of temporal predicates: after, before, begins,
begun by, contains, during, ends, equals, meets, met by, overlaps
and overlapped by.

e) A predicate to test whether the identifier of an object
matches the specified value.

This International Standard defines the XML encoding of metadata
that allows a service to declare which conformance classes,
predicates, operators, operands and functions it supports. This
metadata is referred to as Filter Capabilities.