WMS (Web Map Service) Reader

Transcription

1 FME Readers and Writers 2013 SP1 WMS (Web Map Service) Reader The Web Map Service (WMS) Reader allows FME to retrieve spatially referenced raster maps from a WMS-compliant server. Overview WMS is an OpenGIS Implementation Specification. The WMS specification defines three HTTP operations. These are the GetCapabilities, GetMap and GetFeatureInfo operations. Only the GetCapabilities and GetMap operations are supported in this implementation. The WMS reader adheres to versions 1.1.0, and of the WMS specification. WMS Quick Facts About Quick Facts Tables Format Type Identifier Reader/Writer Licensing Level Dependencies Dataset Type Feature Type Typical File Extensions Automated Translation Support User-Defined Attributes Coordinate System Support Generic Color Support Spatial Index Schema Required Transaction Support Geometry Type WMS Reader Professional None Universal Resource Locator layer name Not applicable Yes No No No Not applicable No wms_type Geometry Support Geometry Supported? Geometry Supported? aggregate no point no circles no polygon no circular arc no raster yes

2 WMS (Web Map Service) Reader Geometry Support Geometry Supported? Geometry Supported? donut polygon no solid no elliptical arc no surface no ellipses no text no line no z values no none yes Reader Overview The WMS reader at this moment supports PNG, GIF, JPEG, TIFF and GeoTIFF raster maps. Only the default style for a layer is supported in this release. Reader Directives The directives processed by the WMS reader are listed below. The suffixes shown are prefixed by the current <ReaderKeyword> in a mapping file. By default, the <ReaderKeyword> for the WMS reader is WMS. DATASET Required/: Required The value for this directive is the URL for the WMS server. A typical URL specifying a WMS server looks like: WMS_DATASET : Web Map Service URL MINX, MINY, MAXX, MAXY Required/ These optional directives are used to specify the value of the rectangular bounding box parameter value that is submitted during a request for feature information. The syntax for the values of these directives is: <ReaderKeyword>_MINX <value> <ReaderKeyword>_MINY <value> <ReaderKeyword>_MAXX <value> <ReaderKeyword>_MAXY <value> All values must be specified in decimal, integer or scientific notation. If all values for MINX, MINY, MAXX and MAXY have a value of 0, then the default bounding boxes for the selected layers are used. :

3 FME Readers and Writers 2013 SP1 Search Envelope Min X, Search Envelope Min Y, Search Envelope Max X, Search Envelope Max Y DEF Required/ Required The syntax for a WMS DEF line is: <ReaderKeyword>_DEF <feature-type> \ wms_selected_layers set(layer1,layer2,...,layern) Where layer1,layer2,...,layern in the wms_selected_layers attributes lists the layers selected for the particular image represented by the DEF line. If one and only one layer is selected then layer1 will match the feature-type, otherwise, feature-type will be the name for requested layers common parent layer. HTTP_AUTH_USER Required/ This optional directive specifies the user name when accessing a password protected HTTP server. The directive has no default value. Example <ReaderKeyword>_HTTP_AUTH_USER someusername Http Authentication User HTTP_AUTH_PASSWORD Required/: This optional directive specifies the password when accessing a password protected HTTP server. The directive has no default value. <ReaderKeyword>_HTTP_AUTH_PASSWORD my123secret : Http Authentication Password HTTP_AUTH_METHOD Required/

4 WMS (Web Map Service) Reader This optional directive specifies the authentication method when accessing a password protected HTTP server. Valid values for this directive are Basic, Digest and NTLM. The default value is Basic. Note: The HTTP basic access authentication is a mechanism designed to allow a client to provide credentials to a server on the assumption that the connection between them is trusted and secure. That is, any credentials passed from client to server can be easily intercepted through an insecure connection. <ReaderKeyword>_HTTP_AUTH_METHOD Digest Http Authentication Method HTTP_PROXY Required/ This optional directive specifies the HTTP proxy to be used for network fetches. The port number may be specified at the end the proxy by appending :[port number] or through the HTTP_PROXY_PORT directive. or <ReaderKeyword>_HTTP_PROXY <ReaderKeyword>_HTTP_PROXY Note: Users may bypass the HTTP_PROXY and HTTP_PROXY directives and still have http proxy support by specifying the http_proxy environment variable. The value for this environment variable should be of the form [protocol://][user:password@] machine[:port], where components within [] are optional. An example value for the http_proxy environment variable is: Http Proxy Address HTTP_PROXY_PORT Required/ This optional directive is used if the HTTP proxy port was not specified in the HTTP_ PROXY directive. Example <ReaderKeyword>_HTTP_PROXY_PORT

5 FME Readers and Writers 2013 SP1 Http Proxy Port HTTP_PROXY_USER Required/ This optional directive specifies the user name when accessing a password protected proxy server. The directive has no default value. <ReaderKeyword>_HTTP_PROXY_USER someusername Http Proxy User HTTP_PROXY_PASSWORD Required/ This optional directive specifies the password when accessing a password protected proxy server. The directive has no default value. <ReaderKeyword>_HTTP_PROXY_PASSWORD my123secret Http Proxy Password HTTP_PROXY_AUTH_METHOD Required/ This optional directive specifies the authentication method when accessing a password protected proxy server. Valid values for this directive are Basic, Digest and NTLM, with Basic being the default value. Example <ReaderKeyword>_HTTP_PROXY_AUTH_METHOD Digest Http Proxy Authorization Method SRS Required/

6 WMS (Web Map Service) Reader This optional directive specifies the desired coordinate system. The default value is CRS:84 for WMS and EPSG:4326 for WMS and SRS <ReaderKeyword>_SRS EPSG:32610 TRANSPARENT Required/ This optional directive sets the background transparency for a map. The map server will send an image with transparent background when this directive is set to Yes and the image format supports transparency (e.g., PNG and GIF). The default value for this directive is No. <ReaderKeyword>_TRANSPARENT Yes Transparent Map Background SPLIT_REQUESTS Required/ When set to Yes this directive instructs the WMS reader to split the selected layers into separate HTTP Get Requests, i.e., if N layers are selected then N separate HTTP GetMap requests are performed fetching N images. The default value for this directive is No. <ReaderKeyword>_SPLIT_REQUESTS Yes : Split GetMap Request MAP_HEIGHT Required/: This optional directive specifies the height in pixels for the image. The default value for this directive is

7 FME Readers and Writers 2013 SP1 <ReaderKeyword>_MAP_HEIGHT 600 : Image Height MAP_WIDTH Required/: This optional directive specifies the width in pixels for the image. The default value for this directive is 560. <ReaderKeyword>_MAP_WIDTH 800 : Image Width MAP_FORMAT Required/: This optional directive specifies the image output format as a MIME type. The output format must be one of the formats listed in the WMS capabilities document. The directive defaults to image/png. <ReaderKeyword>_MAP_FORMAT image/gif : Image Width EXPOSED_ATTRS This directive allows the selection of format attributes to be explicitly added to the reader feature type. This is similar to exposing format attributes on a reader feature type once it has been generated; however, it is even more powerful because it enables schema-driven applications other than Workbench to access and leverage these attributes as if they were explicitly on the schema as user attributes. The result of picking a list of attributes is a comma-separated list of attribute names and types that will be added to the schema features. Currently all reader feature types will receive the same set of additional schema attributes for a given instance of the reader. Required/ Mapping File Syntax Not applicable. While it is possible for FME Objects applications to invoke this directive, the required format is not documented. This directive is intended for use in our GUI applications (for example, Workbench) only

8 WMS (Web Map Service) Reader Additional Attributes to Expose Feature Representation The WMS reader delegates all image reading to the FME raster readers. If only one concrete image layer is selected then the image feature type is set to the name of the layer. If several layer s are selected in the request and if the request is not split into separate GetMap requests then the feature type for the image for the selected layers is set to the earliest common parent layer. Additional attributes with values taken from the WMS capabilities document are attached to each downloaded image. The wms_service_name, wms_service_title, and wms_service_abstract attributes contain metadata information from the WMS service. The wms_layer_name, wms_layer_title, and wms_layer_abstract attributes corresponds to information for the selected layer. If several layers are selected in one request then these attributes will contain information from the common parent layer. The wms_selected_layers selected attribute is a special attribute added by the WMS reader enumerating the selected layers for the particular image, see the WMS DEF line description