2009년 12월 5일 토요일

OGC WFS Operation Quick Reference

웹을 통해 Feature[1] 형식으로 GIS 데이터를 접근하기 위한 인터페이스.

- 공간 데이터를 인코딩하기 위하여 (Geography Markup Language)GML[2]을 사용

- 데이터 접근 제약조건을 위해 Filter Encoding Standard(SES)[3] 사용

◎ WFS Operation

요청

응답

설명

GetCapabilities

XML

서비스 가능한 Layer, Operation, Parameter에 대한 메타정보를 XML로 반환

GetFeature

XML

요청한 레이어의 공간 정보를 XML형식으로 반환

DescribeFeatureType

XML

요청한 Layer에 해당하는 스키마 등 메타정보를 XML로 반환

LockFeature

XML

편집 중 Lock 요청

Transaction

XML

요청한 입력, 수정, 삭제를 처리하여 처리결과를 XML로 반환

◎ Basic WFS

A basic WFS would implement the GetCapabilities, DescribeFeatureType and GetFeature operations. This would be considered a READ-ONLY web feature service.


○ GetCapabilities

A web feature service must be able to describe its capabilities. Specifically, it must indicate which feature types it can service and what operations are supported on each feature type.


예)

http://hostname/wfsservice?service=wfs&version=1.1.0&request=GetCapabilities


○ DescribeFeatureType

A web feature service must be able, upon request, to describe the structure of any feature type it can service.

예1 )서비스중인 모든 레이어 정보
http://hostname/wfsservice?service=wfs&version=1.1.0&request=DescribeFeatureType


예2)  namespace:featuretype 레이어에 대한 정보
http://hostname/wfsservice?service=wfs&version=1.1.0&request=DescribeFeatureType&
   typeName=namespace:featuretype


○ GetFeature

A web feature service must be able to service a request to retrieve feature instances. In addition, the client should be able to specify which feature properties to fetch and should be able to constrain the query spatially and non-spatially.

 

예)
http://hostname/wfsservice?service=wfs&version=1.1.0&request=GetFeature&typeName=namespace:featuretype

http://hostname/wfsservice?service=wfs&version=1.1.0&request=GetFeature&typeName=namespace:featuretype&featureID=feature

http://hostname/wfsservice?service=wfs&version=1.1.0&request=GetFeature&typeName=namespace:featuretype&maxFeatures=N

http://hostname/wfsservice?service=wfs&version=1.1.0&request=GetFeature&typeName=namespace:featuretype&maxFeatures=N&sortBy=property

http://hostname/wfsservice?service=wfs&version=1.1.0&request=GetFeature&typeName=namespace:featuretype&featureID=feature&propertyName=property1,property2

http://hostname/wfsservice?service=wfs&version=1.1.0&request=GetFeature&typeName=namespace:featuretype&bbox=a1,b1,a2,b2

◎ Transaction WFS

A transaction web feature service would support all the operations of a basic web feature service and in addition it would implement the Transaction operation.

Optionally, a transaction WFS could implement the GetGmlObject and/or LockFeature operations.


○ LockFeature

A web feature service may be able to process a lock request on one or more instances of a feature type for the duration of a transaction. This ensures that serializable transactions are supported.


○ Transaction

A web feature service may be able to service transaction requests. A transaction request is composed of operations that modify features; that is create, update, and delete operations on geographic features.

 

◎ Operation 구현 참고

http://www.opengeospatial.org/standards/wfs

http://www.opengeospatial.org/standards/filter

http://www.opengeospatial.org/standards/gml

http://www.opengeospatial.org/standards/sfa

http://www.opengeospatial.org/standards/common


[1] Feature는 공간 속성뿐만 아니라 관계된 비공간 속성도 가지고 있는 현실 세계의 객체(건물, 도로 등)를 추상화한 개념

[2] GML(Geography Markup Language)은 지리 정보 시스템(GIS)등에서 이용하는 공간 데이터나 위치 정보를 포함한 각종의 컨텐츠를 기술하기 위한 XML 베이스의 OGC 표준

[3] Filter Encoding은 쿼리를 위해 공간 및 속성 조건을 설정하기 위한 OGC 표준