Package uk.ac.starlink.vo

Class DalQuery

  • public class DalQuery
extends java.lang.Object
    Represents a particular query to a DAL-like service. DAL refers to the the Data Access Layer family of protocols defined by the IVOA.
    Since:
    2 Feb 2009
    Author:
    Mark Taylor (Starlink)

    • Constructor Summary

      Constructors 
      Constructor Description
      DalQuery​(java.lang.String baseURL, java.lang.String serviceType, double raPos, double decPos, double size, uk.ac.starlink.util.ContentCoding coding)
      Constructs a DAL query based on a service URL.
      DalQuery​(RegResource resource, RegCapabilityInterface capability, java.lang.String serviceType, double raPos, double decPos, double size)
      Constructs a DAL query based on a resource from a registry.

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void addArgument​(java.lang.String name, java.lang.String value)
      Adds an argument to the query.
      java.lang.String doubleToString​(double value)
      Encodes a floating point value as a string for use in a DAL query.
      uk.ac.starlink.table.StarTable execute​(uk.ac.starlink.table.StarTableFactory tfact)
      Executes this query synchronously, returning a StarTable which represents the results.
      static uk.ac.starlink.table.StarTable executeQuery​(java.net.URL qurl, uk.ac.starlink.table.StarTableFactory tfact, uk.ac.starlink.util.ContentCoding coding)
      Submits a synchronous query to a URL and retrieves the result as a StarTable following standard DAL conventions.
      java.lang.String toString()  

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

    • Constructor Detail

      • DalQuery

        public DalQuery​(RegResource resource,
                RegCapabilityInterface capability,
                java.lang.String serviceType,
                double raPos,
                double decPos,
                double size)
        Constructs a DAL query based on a resource from a registry.
        Parameters:
        resource - resource describing the DAL service
        capability - DAL capability from resource
        serviceType - short name for service type; informative, used for error messages etc
        raPos - right ascension of ROI center in degrees
        decPos - declination of ROI center in degrees
        size - ROI size in degrees

      • DalQuery

        public DalQuery​(java.lang.String baseURL,
                java.lang.String serviceType,
                double raPos,
                double decPos,
                double size,
                uk.ac.starlink.util.ContentCoding coding)
        Constructs a DAL query based on a service URL.
        Parameters:
        baseURL - URL forming basis of CGI query for the DAL service
        serviceType - short name for service type; informative, used for error messages etc
        raPos - right ascension of ROI center in degrees
        decPos - declination of ROI center in degrees
        size - size in degrees
        coding - controls HTTP-level byte-stream compression

    • Method Detail

      • addArgument

        public void addArgument​(java.lang.String name,
                        java.lang.String value)
        Adds an argument to the query. No validation is performed to check it is one of the ones that the DAL service knows about.
        Parameters:
        name - service argument name
        value - argument value

      • execute

        public uk.ac.starlink.table.StarTable execute​(uk.ac.starlink.table.StarTableFactory tfact)
                                       throws java.io.IOException
        Executes this query synchronously, returning a StarTable which represents the results. If the query resulted in a QUERY_STATUS of ERROR, or if the returned VOTable document is not comprehensible according to the DAL rules, an IOException will be thrown.
        Parameters:
        tfact - factory which may be used to influence how the table is built
        Throws:
        java.io.IOException - in absence of good data

      • toString

        public java.lang.String toString()
        Overrides:
        toString in class java.lang.Object

      • doubleToString

        public java.lang.String doubleToString​(double value)
        Encodes a floating point value as a string for use in a DAL query. There ought to be a definition within the DAL protocols of how to do this. At time of writing there is not, so the current implementation defers to the ad-hoc implementation in CgiQuery.formatDouble(double), which avoids exponential notation except for very large/small values.
        Parameters:
        value - numeric value
        Returns:
        string equivalent

      • executeQuery

        public static uk.ac.starlink.table.StarTable executeQuery​(java.net.URL qurl,
                                                          uk.ac.starlink.table.StarTableFactory tfact,
                                                          uk.ac.starlink.util.ContentCoding coding)
                                                   throws java.io.IOException
        Submits a synchronous query to a URL and retrieves the result as a StarTable following standard DAL conventions.
        Parameters:
        qurl - query URL
        tfact - table factory
        coding - encoding to use for communications
        Returns:
        table included in DAL result resource
        Throws:
        java.io.IOException