GetCapabilities Response |
The WFS Capabilities document consists of four components: Services, Capabilities, Feature Type, and Filter Capabilities. The WFS Capabilities document includes services , capabilities , element types , Four components of filter capacity.
The service section provides the metadata info for the service itself.
Table 1 Service Section Elements
| Element name | Description |
|
Name |
The name of the WFS service. |
|
Title |
Service title. A short description of the server. |
|
Abstract |
Summary of services. Provides a more descriptive description of the server information. |
|
Keyword |
Keyword. Short words for directory searches. |
|
OnlineResource |
Online resource. Defines the top-level HTTP URL of the service, for example, the home page URL of the service. |
|
Fees |
Cost. Specifies the fee to be paid for using or obtaining data from the WFS service. The keyword NONE means free. |
|
AccessConstraints |
Access restrictions. Indicates the access restrictions for using or obtaining data from the WFS service. The keyword NONE indicates no access restrictions. |
The Capabilities section lists the requests that WFS can handle.
A basic WFS includes three operations: GetCapabilities, DescribeFeatureType, and GetFeature. A transacted WFS includes a Transaction operation and possibly a LockFeature and/or GetFeatureWithLock operation.
Table 2 Competency Section Elements
| Element name | Description |
|
GetCapabilities |
< GetCapabilities> The element defines the distributed computing platforms available for the current service. |
|
DescribeFeatureType |
< DescribeFeatureType> The element is used to define the distributed computing platform available for the current service and the schema description language. XML schema is the only valid schema description language, and the schema references entity can be redefined to include the specific language of the service providers. |
|
Transaction |
< Transaction> The element defines the distributed computing platforms available for the current service. |
|
GetFeature |
< GetFeature> The element defines the distributed computing platforms available for the current service and enumerates valid formats for query results. The RESULTFORMATS entity defines the mandatory output format, GML, but RESULTFORMATS can also be redefined to include a specific format for service providers. |
|
LockFeature |
< LockFeature> The element defines the distributed computing platforms available for the current service. |
HTTP is the only valid distributed computing platform, so there are two ways to define requests: GET and POST. For HTTP GET requests, the onlineResource attribute value is the prefix of the URL (the part before the question mark and the query string, http://hostname[:port]/path/scriptname); For HTTP POST requests, the onlineResource attribute value is the full URL.
The < VendorSpecificCapabilities > element is used to define specific extensions that contain service providers.
This section defines the list of feature types provided by WFS and the operations for each feature type. In addition, additional information about each feature type, such as SRS, is provided.
The < FeatureTypeList > element contains a list of feature types provided by the WFS service and defines the transaction and query elements supported by each feature type.
Table 3. Transaction and Query Elements for Elements
| Element name | Description |
|
Insert |
Insert. Indicates that WFS can create new instances of feature types. |
|
Update |
Update. Indicates that WFS can update existing features. |
|
Delete |
Delete. Represents the types of features that WFS can delete. |
|
Query |
Inquire. Indicates that WFS is able to perform query operations on a feature type. |
|
Lock |
Lock. Represents an instance of a feature type that WFS can lock. |
The Transaction and Query elements can be specified globally to describe all feature types, or locally to describe specific feature types contained in a < FeatureTypeList > element. The globally specified Transaction and Query elements can be inherited by each feature type contained in the < FeatureTypeList > element, and can be extended by specific local Transaction and Query elements. For example, the < Query > element can globally specify all feature types in the < FeatureTypeList > element, while the < Update > element can only locally specify a small subset of feature types. If the Transaction and Query elements are not defined anywhere, the default < Query > element is implicitly defined in all feature types of the < FeatureTypeList > element.
The elements in the < FeatureTypeList > element that describe the feature type are shown in the following table:
Table 4 Describes the Elements of the Feature Type
| Element name | Description |
|
Name |
The name of the feature type. Feature type The type specified in the namespace. This element is required. |
|
Title |
Feature title. A short description of the feature type. |
|
Abstract |
Summary of elements. A description with more information about the feature type. |
|
Keyword |
Keyword. Short words foreasy directory searching. |
|
SRS |
Spatial coordinate reference system. The spatial coordinate reference system on which the feature is based. The SRS can be in POSC (Petrotechnical Open Software Corporation) format, in the form "EPSG: < POSC Code >", or in URL format. SuperMap iServer currently only supports the POSC (EPSG: 4326) format. |
|
Operations |
Operation. Used to define the operations supported by a feature type. Locally defined operations take precedence over globally defined operations. |
|
LatLongBoundingBox |
Bounding box. Represents a closed rectangular boundary for a feature type based on SRS (EPSG: 4326). Facilitate geographic searches by specifying where a particular feature type exists. Since multiple LatLongBoundingBoxes can be specified, WFS can specify where different data exists. |
|
MetadataURL |
Metadata URL. WFS can use 0 or more < MetadataURL> The element provides details and standard metadata for specific feature type data. The type attribute indicates the standard used for the metadata; the format attribute indicates how the metadata is composed. There are currently two categories of definitions: 'TC211' = ISO TC211 19115 and 'FGDC' = FGDC CSDGM. |
The filter capabilities section is optional, and if present, indicates that WFS will support the corresponding operation. If the filter capabilities section is not defined, the client will only support the minimum default filtering operations defined in the filter encoding implementation specification.
The version attribute specifies the specification revision of the current schema. The format consists of one, two, or three separated integers: “x”、“x.y”, or “x.y.z”, with the most significant digit first. Later versions are in the form of monotonically increasing numbers.
The updateSequence attribute is a sequence number used to manage the contents of the capabilities document. For example, if a feature server adds some feature types, it will add an update sequence to inform the directory server that the previous cache version is no longer valid. The format of the attribute is a positive integer.
The response result of the request example is as follows: