Class TapQuery

java.lang.Object
uk.ac.starlink.vo.TapQuery

public class TapQuery extends Object
Represents a query to be made to a Table Access Protocol service. This class aggregates the information which needs to be sent to make such a query and provides methods to submit the query synchronously or asynchronously. It also contains some static methods to perform other TAP-related operations.
Since:
8 Apr 2011
Author:
Mark Taylor
See Also:
  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    static final uk.ac.starlink.votable.DataFormat
    Default VOTable serialization format for uploading VOTables to a TAP service.
  • Constructor Summary

    Constructors
    Constructor
    Description
    TapQuery(URL serviceUrl, String adql, Map<String,String> extraParams)
    Convenience constructor that uses a URL rather than a TapService object.
    TapQuery(TapService service, String adql, Map<String,String> extraParams)
    Constructs a query with no uploaded tables.
    TapQuery(TapService service, String adql, Map<String,String> extraParams, Map<String,uk.ac.starlink.table.StarTable> uploadMap, long uploadLimit, uk.ac.starlink.votable.VOTableWriter vowriter)
    Constructs a query with uploaded tables.
  • Method Summary

    Modifier and Type
    Method
    Description
    createSyncConnection(uk.ac.starlink.util.ContentCoding coding)
    Opens a URL connection for the result of synchronously executing this query.
    uk.ac.starlink.table.StarTable
    executeSync(uk.ac.starlink.table.StoragePolicy storage, uk.ac.starlink.util.ContentCoding coding)
    Executes this query synchronously and returns the resulting table.
    boolean
    executeSync(uk.ac.starlink.table.TableSink sink, uk.ac.starlink.util.ContentCoding coding)
    Executes this query synchronously and streams the resulting table to a table sink.
    Takes a URLConnection and repeatedly follows 303 redirects until a non-303 status is achieved.
    Returns the text of the ADQL query for this object.
    static uk.ac.starlink.table.StarTable
    getResult(UwsJob uwsJob, uk.ac.starlink.util.ContentCoding coding, uk.ac.starlink.table.StoragePolicy storage)
    Reads and returns the table that resulted from a successful TAP query, represented by a given UWS job.
    Returns the map of streamed parameters to be passed to the TAP service.
    Returns the map of string parameters to be passed to the TAP service.
    Returns the TAP service object to which this query will be submitted.
    getVOTableStream(URLConnection conn, uk.ac.starlink.util.ContentCoding coding)
    Gets an input stream from a URL connection that should contain a VOTable.
    static uk.ac.starlink.table.StarTable
    readResultVOTable(URLConnection conn, uk.ac.starlink.util.ContentCoding coding, uk.ac.starlink.table.StoragePolicy storage)
    Reads a VOTable which may represent a successful result or an error.
    static <T> T
    scalarQuery(TapService service, String adql, Class<T> clazz)
    Utility method to obtain a single-cell table as the result of a synchronous TAP query.
    static boolean
    streamResultVOTable(URLConnection conn, uk.ac.starlink.util.ContentCoding coding, uk.ac.starlink.table.TableSink sink)
    Streams a VOTable document which may represent a successful result or an error.
    Submits this query asynchronously and returns the corresponding UWS job.
    static uk.ac.starlink.table.StarTable
    waitForResult(UwsJob uwsJob, uk.ac.starlink.util.ContentCoding coding, uk.ac.starlink.table.StoragePolicy storage, long pollMillis)
    Blocks until the TAP query represented by a given UWS job has completed, then returns a table based on the result.
    static URL
    waitForResultUrl(UwsJob uwsJob, long pollMillis)
    Blocks until the TAP query represented by a given UWS job has completed, then returns the URL from which the successful result can be obtained.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
  • Field Details

    • DFLT_UPLOAD_SER

      public static final uk.ac.starlink.votable.DataFormat DFLT_UPLOAD_SER
      Default VOTable serialization format for uploading VOTables to a TAP service. The value is currently DataFormat.TABLEDATA. BINARY would be more efficient and ought to be OK, but at time of writing at least CADC, and under some circumstances other services, work properly with TABLEDATA but not BINARY uploaded tables, so for now conform to the lowest common denominator.
  • Constructor Details

    • TapQuery

      public TapQuery(TapService service, String adql, Map<String,String> extraParams)
      Constructs a query with no uploaded tables.
      Parameters:
      service - TAP service description
      adql - text of ADQL query
      extraParams - key->value map for optional parameters; if any of these match the names of standard parameters (upper case) the standard values will be overwritten, so use with care (may be null)
    • TapQuery

      public TapQuery(TapService service, String adql, Map<String,String> extraParams, Map<String,uk.ac.starlink.table.StarTable> uploadMap, long uploadLimit, uk.ac.starlink.votable.VOTableWriter vowriter) throws IOException
      Constructs a query with uploaded tables. May throw an IOException if the tables specified for upload exceed the stated upload limit.
      Parameters:
      service - TAP service description
      adql - text of ADQL query
      extraParams - key->value map for optional parameters; if any of these match the names of standard parameters (upper case) the standard values will be overwritten, so use with care (may be null)
      uploadMap - name->table map of tables to be uploaded to the service for the query (may be null)
      uploadLimit - maximum number of bytes that may be uploaded; if negative, no limit is applied, ignored if uploadMap null or empty
      vowriter - serializer for producing content of uploaded tables; ignored if uploadMap null or empty, if null a default value is used
      Throws:
      IOException - if upload tables exceed the upload limit
    • TapQuery

      public TapQuery(URL serviceUrl, String adql, Map<String,String> extraParams)
      Convenience constructor that uses a URL rather than a TapService object. This just uses TapServices.createDefaultTapService(java.lang.String) and then invokes one of the other constructors.

      This form is mildly deprecated, it is preferred to create your own TapService as above and submit that to one of the other constructors instead. It's present because other classes rely on it, but there is no intention to add URL-based constructors corresponding to the other TapService-based forms.

      Parameters:
      serviceUrl - base URL of TAP service
      adql - text of ADQL query
      extraParams - key->value map for optional parameters; if any of these match the names of standard parameters (upper case) the standard values will be overwritten, so use with care (may be null)
  • Method Details

    • getAdql

      public String getAdql()
      Returns the text of the ADQL query for this object.
      Returns:
      ADQL query text
    • getTapService

      public TapService getTapService()
      Returns the TAP service object to which this query will be submitted.
      Returns:
      service locations
    • getStringParams

      public Map<String,String> getStringParams()
      Returns the map of string parameters to be passed to the TAP service.
      Returns:
      name->value map for TAP string parameters
    • getStreamParams

      public Map<String,HttpStreamParam> getStreamParams()
      Returns the map of streamed parameters to be passed to the TAP service.
      Returns:
      name->value map for TAP stream parameters
    • executeSync

      public uk.ac.starlink.table.StarTable executeSync(uk.ac.starlink.table.StoragePolicy storage, uk.ac.starlink.util.ContentCoding coding) throws IOException
      Executes this query synchronously and returns the resulting table.
      Parameters:
      storage - storage policy for caching table data
      coding - configures HTTP compression
      Returns:
      result table
      Throws:
      IOException
    • executeSync

      public boolean executeSync(uk.ac.starlink.table.TableSink sink, uk.ac.starlink.util.ContentCoding coding) throws IOException, SAXException
      Executes this query synchronously and streams the resulting table to a table sink. If the result is a TAP error document, it will be presented as an exception thrown from this method. Overflow status of a successful result is provided by the return value.
      Parameters:
      sink - table destination
      coding - configures HTTP compression
      Returns:
      true iff the result was marked as overflowed
      Throws:
      IOException
      SAXException
    • createSyncConnection

      public HttpURLConnection createSyncConnection(uk.ac.starlink.util.ContentCoding coding) throws IOException
      Opens a URL connection for the result of synchronously executing this query.
      Parameters:
      coding - HTTP content-coding policy result should be interpreted with same coding
      Returns:
      HTTP connection containing query result
      Throws:
      IOException
    • submitAsync

      public UwsJob submitAsync() throws IOException
      Submits this query asynchronously and returns the corresponding UWS job. The job is not started.
      Returns:
      new UWS job for this query
      Throws:
      IOException
    • waitForResultUrl

      public static URL waitForResultUrl(UwsJob uwsJob, long pollMillis) throws IOException, InterruptedException
      Blocks until the TAP query represented by a given UWS job has completed, then returns the URL from which the successful result can be obtained. If the job does not complete successfully, an IOException is thrown instead.
      Parameters:
      uwsJob - started UWS job representing an async TAP query
      pollMillis - polling interval in milliseconds
      Returns:
      open URL connection to result stream
      Throws:
      IOException
      InterruptedException
    • waitForResult

      public static uk.ac.starlink.table.StarTable waitForResult(UwsJob uwsJob, uk.ac.starlink.util.ContentCoding coding, uk.ac.starlink.table.StoragePolicy storage, long pollMillis) throws IOException, InterruptedException
      Blocks until the TAP query represented by a given UWS job has completed, then returns a table based on the result. In case of job failure, an exception will be thrown instead.
      Parameters:
      uwsJob - started UWS job representing an async TAP query
      coding - configures HTTP compression
      storage - storage policy for caching table data
      pollMillis - polling interval in milliseconds
      Returns:
      result table
      Throws:
      IOException
      InterruptedException
    • getResult

      public static uk.ac.starlink.table.StarTable getResult(UwsJob uwsJob, uk.ac.starlink.util.ContentCoding coding, uk.ac.starlink.table.StoragePolicy storage) throws IOException
      Reads and returns the table that resulted from a successful TAP query, represented by a given UWS job. The query is assumed to have requested output in VOTable format. If the job has not reached COMPLETED phase, an IOException will result.
      Parameters:
      uwsJob - successfully completed UWS job representing an async TAP query
      coding - configures HTTP compression
      storage - storage policy for caching table data
      Returns:
      the result of reading the TAP result as a table
      Throws:
      IOException
    • scalarQuery

      public static <T> T scalarQuery(TapService service, String adql, Class<T> clazz) throws IOException
      Utility method to obtain a single-cell table as the result of a synchronous TAP query.
      Parameters:
      service - TAP service description
      adql - query string
      clazz - class of required value
      Returns:
      single value, or null if no rows
      Throws:
      IOException - if required result cannot be got
    • readResultVOTable

      public static uk.ac.starlink.table.StarTable readResultVOTable(URLConnection conn, uk.ac.starlink.util.ContentCoding coding, uk.ac.starlink.table.StoragePolicy storage) throws IOException
      Reads a VOTable which may represent a successful result or an error. If it represents an error (in accordance with the TAP rules for expressing this), an exception will be thrown.
      Parameters:
      conn - connection to table resource
      coding - HTTP content coding policy used to prepare connection
      storage - storage policy
      Returns:
      table result of successful query
      Throws:
      IOException
    • streamResultVOTable

      public static boolean streamResultVOTable(URLConnection conn, uk.ac.starlink.util.ContentCoding coding, uk.ac.starlink.table.TableSink sink) throws IOException, SAXException
      Streams a VOTable document which may represent a successful result or an error. If it represents an error (in accordance with the TAP rules for expressing this), an exception will be thrown. Overflow status of a successful result is provided by the return value.

      Note: any XML that comes after the TABLE element of the result table is ignored for the purposes of reporting the table metadata. The only thing after the end of the TABLE that affects the result of this method is the overflow flag, which affects the return value. So if you need to pick up items which might be in trailing elements, for instance Service Descriptors in later RESOURCE elements, you will have to use a different method.

      Parameters:
      conn - connection to table resource
      coding - HTTP content coding policy used to prepare connection
      sink - destination for table result of succesful query
      Returns:
      true iff the result was marked as overflowed
      Throws:
      IOException
      SAXException
    • getVOTableStream

      public static InputStream getVOTableStream(URLConnection conn, uk.ac.starlink.util.ContentCoding coding) throws IOException
      Gets an input stream from a URL connection that should contain a VOTable.
      Parameters:
      conn - connection to result of TAP service call
      coding - HTTP content coding policy used to prepare connection
      Returns:
      stream containing a response table (error or result)
      Throws:
      IOException
    • followRedirects

      public static URLConnection followRedirects(URLConnection conn) throws IOException
      Takes a URLConnection and repeatedly follows 303 redirects until a non-303 status is achieved. Infinite loops are defended against. The Accept-Encoding header, if present, is propagated to redirect targets.
      Parameters:
      conn - initial URL connection
      Returns:
      target URL connection (if no redirects, the same as hconn)
      Throws:
      IOException