Package org.geotools.data.ows

Class AbstractOpenWebService<C extends Capabilities,R>

Object
AbstractOpenWebService<C,R>
Direct Known Subclasses:
WebMapServer, WebMapTileServer, WFSClient
public abstract class AbstractOpenWebService<C extends Capabilities,R> extends Object
This abstract class provides a building block for one to implement an Open Web Service (OWS) client. Each OWS is usually defined by an OGC specification, available at http://www.opengeospatial.org.

This class provides version negotiation, Capabilities document retrieval, and a request/response infrastructure. Implementing subclasses need to provide their own Specifications (representing versions of the OWS to be implemented) and their own request/response instances.

Author:
Richard Gould

  • Field Details

    • serverURL

      protected final URL serverURL

    • headers

      protected final Map<String,String> headers

    • capabilities

      protected C extends Capabilities capabilities

    • info

      protected ServiceInfo info

    • resourceInfo

      protected Map<R,ResourceInfo> resourceInfo

    • specs

      protected Specification[] specs
      Contains the specifications that are to be used with this service

    • specification

      protected Specification specification

    • hints

      protected Map<String,Object> hints
      Hints, now used for the XML parsing *

    • LOGGER

      protected static final Logger LOGGER

  • Constructor Details

  • Method Details

    • setHttpClient

      @Deprecated public void setHttpClient(HTTPClient httpClient)
      Deprecated.
      httpClient should be treated as a final
      Parameters:
      httpClient -

    • getHTTPClient

      public HTTPClient getHTTPClient()

    • getCapabilities

      public abstract C getCapabilities()
      Get the getCapabilities document. If there was an error parsing it during creation, it will return null (and it should have thrown an exception during creation).
      Returns:
      a Capabilities object, representing the Capabilities of the server

    • getInfo

      public ServiceInfo getInfo()
      Description of this service.

      Provides a very quick description of the service, for more information please review the capabilitie document.

      Returns:
      description of this service.

    • createInfo

      protected abstract ServiceInfo createInfo()
      Implemented by a subclass to describe service
      Returns:
      ServiceInfo

    • getInfo

      public ResourceInfo getInfo(R resource)

    • createInfo

      protected abstract ResourceInfo createInfo(R resource)

    • setupSpecifications

      protected abstract void setupSpecifications()
      Sets up the specifications/versions that this server is capable of communicating with.

    • negotiateVersion

      protected C negotiateVersion() throws IOException, ServiceException
      Version number negotiation occurs as follows (credit OGC):
      • 1) If the server implements the requested version number, the server shall send that version.
      • 2a) If a version unknown to the server is requested, the server shall send the highest version less than the requested version.
      • 2b) If the client request is for a version lower than any of those known to the server, then the server shall send the lowest version it knows.
      • 3a) If the client does not understand the new version number sent by the server, it may either cease communicating with the server or send a new request with a new version number that the client does understand but which is less than that sent by the server (if the server had responded with a lower version).
      • 3b) If the server had responded with a higher version (because the request was for a version lower than any known to the server), and the client does not understand the proposed higher version, then the client may send a new request with a version number higher than that sent by the server.

      The OGC tells us to repeat this process (or give up). This means we are actually going to come up with a bit of setup cost in figuring out our GetCapabilities request. This means that it is possible that we may make multiple requests before being satisfied with a response.

      Also, if we are unable to parse a given version for some reason, for example, malformed XML, we will request a lower version until we have run out of versions to request with. Thus, a server that does not play nicely may take some time to parse and might not even succeed.

      Returns:
      a capabilities object that represents the Capabilities on the server
      Throws:
      IOException - if there is an error communicating with the server, or the XML cannot be parsed
      ServiceException - if the server returns a ServiceException

    • internalIssueRequest

      protected Response internalIssueRequest(Request request) throws IOException, ServiceException
      Issues a request to the server and returns that server's response. It asks the server to send the response gzipped to provide a faster transfer time.
      Parameters:
      request - the request to be issued
      Returns:
      a response from the server, which is created according to the specific Request
      Throws:
      IOException - if there was a problem communicating with the server
      ServiceException - if the server responds with an exception or returns bad content

    • issueRequest

      public GetCapabilitiesResponse issueRequest(GetCapabilitiesRequest request) throws IOException, ServiceException
      Throws:
      IOException
      ServiceException

    • setLoggingLevel

      public void setLoggingLevel(Level newLevel)

    • getHints

      public Map<String,Object> getHints()
      Returns the hints affecting the service operations

    • setHints

      public void setHints(Map<String,Object> hints)
      Sets the hints affecting the service operations