Package uk.ac.starlink.vo

Class DalQuery

java.lang.Object
uk.ac.starlink.vo.DalQuery
public class DalQuery extends 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(String baseURL, 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, String serviceType, double raPos, double decPos, double size)
    Constructs a DAL query based on a resource from a registry.

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    addArgument(String name, String value)
    Adds an argument to the query.
    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(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.
    String
    toString()
     

    Methods inherited from class java.lang.Object

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

  • Constructor Details

    • DalQuery

      public DalQuery(RegResource resource, RegCapabilityInterface capability, 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(String baseURL, 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 Details

    • addArgument

      public void addArgument(String name, 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 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:
      IOException - in absence of good data

    • toString

      public String toString()
      Overrides:
      toString in class Object

    • doubleToString

      public 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(URL qurl, uk.ac.starlink.table.StarTableFactory tfact, uk.ac.starlink.util.ContentCoding coding) throws 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:
      IOException