GetCapabilities Request |
After implement the GetCapabilities operation, the server will return metadata document in XML format for the WFS 2.0,0 service. The document primarily contains Service Metadata, Service Provider, Service Capabilities, Feature Types and Filter and those are required parts.
ServiceIdentification is specific metadata, which is the overview description of the service. It includes three required elements including Title, ServiceType, ServiceType Version and some optional elements including Profile, Abstract, Keywords, Fees and AccessConstraints.
Table 1 ServiceIdentification Element
| Element Name | O/M | Description |
|
Title |
Mandatory |
Service title. The brief description of the service, which can be one or multiple |
|
ServiceType |
Mandatory |
Service type. Request WFS 2.0.0 service. The service type needs to be set to WFS. |
|
ServiceTypeVersion |
Mandatory |
Service version number. Request WFS 2.0.0 service. The service version number needs to be set to 2.0.0. |
|
Profile |
Optional |
Identifier of WFS application introduction. This element is not contained in the result returned by SuperMap iServer currently. |
|
Abstract |
Optional |
Service abstract. Provide brief description of server information provided. This element is not contained in the result returned by SuperMap iServer currently. |
|
Keywords |
Optional |
Keywords. One or multiple commonly used words or phrases used to describe the server. There is not requirement on order for the phrases and words. This element is not contained in the result returned by SuperMap iServer currently. |
|
Fees |
Optional |
Server fee. This element can be ignored if there is no fee for the server. If this element is used, none indicates free. This element is not contained in the result returned by SuperMap iServer currently. |
|
AccessConstraints |
Optional |
Access restriction. It can be ignored if there are no access limits to the server. If this element has been used, none indicates no access limits. There is no accurate syntax definition to the content of this element, and the client can display user information and behavior content. This element is not contained in the result returned by SuperMap iServer currently. |
ServiceProvider indicates information about service provider, and it includes elements such as ProviderName, ProviderSite and ServiceContact.
Table 2 ServiceProvider Element
| Element Name | O/M | Description |
|
ProviderName |
Mandatory |
Provider name. Uniquely identifies the service provider. |
|
ProviderSite |
Mandatory |
Provider address. |
|
ServiceContact |
Mandatory |
Contact information for the service provider. |
OperationsMetadata describes all request operations and URIs corresponding to the request operations supported by the current service. The OperationsMetadata element must contain one or more Operations elements. The OperationsMetadata element can also contain 0 or more Constraint elements and each Constraint element represents a constraint condition. Description of the OperationsMetadata element is in table 3.
Table 3 OperationsMetadata Element
| Element Name | O/M | Description |
| Operation |
Mandatory |
Operation. It is used to uniquely identify operations supported by the service. Each Operation node corresponds to an operation, and the operation is identified by the name property, <Operation name="GetCapabilities"> for instance. Details of Operation is introduced in Table 4. |
|
Parameter |
Optional |
Parameter. It is used to specify the valid domains of one or more operations supported by the service. The name property indicates the parameter name; while the Value element indicates the valid values of the parameter. These parameters can be the input and output parameters for the operations. This element is not contained in the result returned by SuperMap iServer currently. |
| Constraint |
Mandatory |
Constraints. IT is corresponding to the valid domain constraints for the non-parameter property of the service. The name property indicates the non-parameter name, and the DefaultValue element provides the default value, either True or False, for the property. |
| ExtendedCapabilities |
Optional |
Extension capability. It is the description for the additional capabilities of the server and software. This element is not contained in the result returned by SuperMap iServer currently. |
Each Operation element must contain one or more DCP (Distributed Computing Platform) information for the operation. Besides, the Operation element can also contain parameters such as Parameter, Constraint and Metadata.
| Element Name | O/M | Description |
| name |
Mandatory |
Operations name. Each Operation element has one operation name, GetCapabilities for instance. The representation method is <Operation name="GetCapabilities">. |
| DCP |
Mandatory |
The DCP information of the operation. Each Operation element can contain one or more DCP elements. Since only HTTP DCP has been defined currently, each Operation only contains one DCP element, that is, HTTP. Generally, the HTTP element in WFS service should at least contain one Get or one Post, or one Get and one Post, used for indicating request methods supported by the service. |
| Parameter |
Mandatory |
Parameter. It is used to specify the valid domain of this operation. The name property is used to identify the parameter name, and the Value element provides the valid values for the parameter. These parameters can be input/output parameters for the operations. The representation method of the GetCapabilities operation is as follows: <ows:Parameter name="AcceptVersions"> <ows:AllowedValues> <ows:Value>2.0.0</ows:Value> </ows:AllowedValues> </ows:Parameter> If the valid domain has been specified in a specific Operation, the valid domain of parameter with the same name in OperationsMetadata will be overwritten. |
| Constraint |
Optional |
Constraint. It is corresponding to the valid domain constraints for the non-parameter property of the service. The name property indicates the non-parameter name, and the DefaultValue element provides the default value, either True or False, for the property. If the valid domain of a non-parameter property has been specified in a specific Operation, the valid domain constraint of non-parameter property with the same name in OperationsMetadata will be overwritten. This element is not contained in the result returned by SuperMap iServer currently. |
| Metadata |
Optional |
Metadata. The metadata about the current operation and implementation. This element is not contained in the result returned by SuperMap iServer currently. |
FeatureTypeList element lists all element types that can be provided by WFS 2.0.0. The FeatureTypeList element can contain one or more FeatureType elements, and each FeatureType element corresponds to a type of element. Description of the FeatureType is shown as in the table below:
Table 5 FeatureType Element
| Element Name | O/M | Description |
|
Name |
Mandatory |
Feature type name. Feature type is the type specified in the namespace. |
|
Title |
Mandatory |
Feature title. The brief description of the feature type. |
|
Abstract |
Optional |
Feature abstract. The description of more information about the feature type. This element is not contained in the result returned by SuperMap iServer currently. |
|
Keywords |
Optional |
Keywords. The short keywords for catalog searching. This element is not contained in the result returned by SuperMap iServer currently. |
|
DefaultCRS |
Mandatory |
The default coordinate reference system. The DefaultCRS element indicates which coordinate reference system shall be used by a WFS to express the state of compatible spatial properties if not otherwise explicitly identified within a query or transaction request. For example, If a GetFeature request specifies no CRS value for the Query srsName attribute, any compatible spatial properties of feature data satisfying the request shall be expressed using URL format. If the DefaultCRS is different from but compatible with the internal storage CRS, then the WFS shall support a transformation between the DefaultCRS and the internal storage CRS. The effects of such a transformation shall be considered when determining and declaring the guaranteed data accuracy. |
|
OtherCRS |
Optional |
Other coordinate reference system. The OtherCRS element shall be used to indicate other supported CRSs within transaction and query requests. A 'supported CRS' means that the WFS supports the transformation of compatible spatial properties between the OtherCRS and the internal storage CRS. The effects of such a transformation shall be considered when determining and declaring the guaranteed data accuracy. This element is not contained in the result returned by SuperMap iServer currently. |
|
NoCRS |
Optional |
None coordinate reference system. The NoCRS element shall be used for feature types that have no spatial properties, and therefore no CRS whatsoever. It is not a requirement for Features and FeatureCollections to have spatial properties. The NoCRS element shall never imply, and therefore cannot be used for, semantics of "Unknown CRS". This element is used as an identifying label only, and therefore has no element or attribute content. |
|
OutputFormats |
Optional |
The output formats. The OutputFormats element shall be a list of MIME types indicating the output formats that may be generated for a feature type. If this optional element is not specified, then all the result formats listed for the GetFeature operation are assumed to be supported. This element is not contained in the result returned by SuperMap iServer currently. |
|
WGS84BoundingBox |
Mandatory |
WGS 84 bounding box. The WGS84BoundingBox element may be used to indicate the edges of an enclosing rectangle in decimal degrees of latitude and longitude in WGS84. Its purpose is to facilitate geographic searches by indicating where instances of the particular feature type exist. Since multiple WGS84BoundingBox elements may be specified, a WFS may indicate where various clusters of data exist. This knowledge aids client applications by letting them know where they should query in order to have a high probability of finding feature data. |
|
MetadataUR |
Optional |
Metadata. A WFS may use zero or more MetadataURL elements to offer detailed metadata about the data in a particular feature type. The xlink:href element shall be used to reference any metadata. This element is not contained in the result returned by SuperMap iServer currently. |
|
ExtendedDescription |
Optional |
The extended description. A WFS may add elements to the description of a feature type, without having to redefine the capabilities schema, using the ExtendedDescription element. The ExtendedDescription element contains one or more Element elements. The Element element includes a name attribute, a type attribute and contains a value list enumerating one or more values for the named extended descriptive element. The name attribute is used to designate the name of the extended descriptive element . The type attribute is used to designate a type for the values in the value list of the extended descriptive element. The type shall be taken from the list of builtin types defined by XML Schema. This element is not contained in the result returned by SuperMap iServer currently. |
FilterCapabilities is used to declare expressions for constraining query operations in advance. The client side application can check conent of the FilterCapabilities part in the Capabilities document to determine which operations and types are supported by the filter expression. FilterCapabilities element is introduced in the table below:
Table 5 FilterCapabilities Element
| Element Name | O/M |
| Conformance |
Mandatory |
|
idCapabilities |
Mandatory |
| ScalarCapabilities |
Mandatory |
| SpatialCapabilities |
Mandatory |
| TemporalCapabilities |
Optional |
| AvailableFunctions |
Optional |
| ExtendedCapabilities |
Optional |
Conformance indicates the constraint condition list, which can constrain the valid domains of the non-parameter attributes applied to the server. Multiple Constraint elements are allowed to be included and each Constraint element represents a constraint method. The name attribute of the Constraint element can be used to identify non-parameter attribute name and the DefaultValue element specifies the default value TRUE/FALSE of the attribute.
The response of the Request example is as follows: