uk.ac.starlink.votable

Class VOTableBuilder

java.lang.Object

uk.ac.starlink.table.formats.DocumentedTableBuilder

uk.ac.starlink.votable.VOTableBuilder

All Implemented Interfaces:

Documented, DocumentedIOHandler, MultiTableBuilder, TableBuilder

public class VOTableBuilder
extends DocumentedTableBuilder
implements MultiTableBuilder

Implementation of the TableBuilder interface which gets StarTables from VOTable documents.

Author:

Mark Taylor (Starlink)

Constructor Summary

Constructors

Constructor and Description
VOTableBuilder() Default constructor.
VOTableBuilder(boolean strict) Constructs a builder with explicit setting of whether VOTable standard interpreation is strict or not.

Method Summary

Modifier and Type	Method and Description
boolean	canImport(DataFlavor flavor) Returns true for flavors which have MIME types starting text/xml application/xml application/x-votable+xml
boolean	canStream() Indicates whether this handler can read tables from a stream.
boolean	docIncludesExample() Indicates whether the serialization of some (short) example table should be added to the user documentation for this handler.
String	getFormatName() Returns the string "VOTable".
String	getXmlDescription() Returns user-directed documentation in XML format.
StarTable	makeStarTable(DataSource datsrc, boolean wantRandom, StoragePolicy storagePolicy) Makes a StarTable out of a DataSource which points to a VOTable.
TableSequence	makeStarTables(DataSource datsrc, StoragePolicy storagePolicy) Constructs a sequence of StarTables based on a given DataSource.
void	streamStarTable(InputStream istrm, TableSink sink, String index) Acquires the data from a single TABLE element in a VOTable document, writing the result to a sink.

Methods inherited from class uk.ac.starlink.table.formats.DocumentedTableBuilder

getExtensions, looksLikeFile

Methods inherited from class java.lang.Object

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

Methods inherited from interface uk.ac.starlink.table.TableBuilder

looksLikeFile

Methods inherited from interface uk.ac.starlink.table.formats.DocumentedIOHandler

matchesExtension, readText, toLink

Constructor Detail

VOTableBuilder

public VOTableBuilder()

Default constructor. Strictness of VOTable standard enforcement is determined by VOElementFactory.isStrictByDefault().

VOTableBuilder

public VOTableBuilder(boolean strict)

Constructs a builder with explicit setting of whether VOTable standard interpreation is strict or not.

Parameters:

strict - true iff you want strict enforcement of VOTable standard

See Also:

VOElementFactory.setStrict(boolean)

Method Detail

getFormatName

public String getFormatName()

Returns the string "VOTable".

Specified by:

getFormatName in interface TableBuilder

Returns:

format name

makeStarTable

public StarTable makeStarTable(DataSource datsrc,
                               boolean wantRandom,
                               StoragePolicy storagePolicy)
                        throws TableFormatException,
                               IOException

Makes a StarTable out of a DataSource which points to a VOTable. If the source has a position attribute, it is currently interpreted as an index into a breadth-first list of the TABLE elements in the document pointed to by datsrc, thus it must be a non-negative integer less than the number of TABLE elements. If it has no position attribute, the first TABLE element is used. The interpretation of the position should probably change or be extended in the future to allow XPath expressions.

Specified by:

makeStarTable in interface TableBuilder

Parameters:

datsrc - the location of the VOTable document to use

wantRandom - whether, preferentially, a random access table should be returned (doesn't guarantee that it will be random)

storagePolicy - a StoragePolicy object which may be used to supply scratch storage if the builder needs it

Returns:

a StarTable made out of datsrc, or null if this handler can't handle it

Throws:

TableFormatException - if the table is not of a kind that can be handled by this handler

IOException - if an unexpected I/O error occurs during processing

makeStarTables

public TableSequence makeStarTables(DataSource datsrc,
                                    StoragePolicy storagePolicy)
                             throws TableFormatException,
                                    IOException

Description copied from interface: MultiTableBuilder

Constructs a sequence of StarTables based on a given DataSource. If the source is not recognised or this object does not know how to make tables from it, then a TableFormatException should be thrown. If this builder thinks it should be able to handle the source but an error occurs during processing, an IOException can be thrown.

If the position of the data source is not null, then this method should return a sequence containing a single table, the one which would be returned by the makeStarTable method with that position.

Specified by:

makeStarTables in interface MultiTableBuilder

Parameters:

datsrc - the DataSource containing the table resource

storagePolicy - a StoragePolicy object which may be used to supply scratch storage if the builder needs it

Returns:

an array of StarTables read from datsrc

Throws:

TableFormatException - if the table is not of a kind that can be handled by this handler

IOException - if an unexpected I/O error occurs during processing

canImport

public boolean canImport(DataFlavor flavor)

Returns true for flavors which have MIME types starting

• text/xml
• application/xml
• application/x-votable+xml

Specified by:

canImport in interface TableBuilder

Parameters:

flavor - the DataFlavor whose suitability as stream input is to be assessed

Returns:

true iff this builder reckons it stands a good chance of turning a stream of type flavor into a StarTable

streamStarTable

public void streamStarTable(InputStream istrm,
                            TableSink sink,
                            String index)
                     throws IOException

Acquires the data from a single TABLE element in a VOTable document, writing the result to a sink. This can be used if only one-shot access to the data is required. Invocation of this method should be cheap on memory even for large XML documents and/or tables. Invocation is synchronous, so the method only returns when the streaming has been done (successfully or otherwise).

Note that only table metadata that precedes the TABLE element in the XML stream can be picked up when using this method. If there are any XML elements following the end of the TABLE whose content would normally show up in table metadata, it will be ignored when using this method.

For more flexible streamed access to VOTable data, use a TableContentHandler.

Specified by:

streamStarTable in interface TableBuilder

Parameters:

istrm - stream from which the VOTable document will be supplied

sink - callback interface into which the table metadata and data will be dumped

index - if present, a string representation of the index of the table in the document to be read - "0" means the first one encountered, "1" means the second, etc. If it's null or not of numeric form the first table will be used

Throws:

TableFormatException - if the table can't be streamed or the data is malformed

IOException - if some other error occurs

canStream

public boolean canStream()

Description copied from class: DocumentedTableBuilder

Indicates whether this handler can read tables from a stream.

Specified by:

canStream in class DocumentedTableBuilder

Returns:

true iff this handler can read from streams

docIncludesExample

public boolean docIncludesExample()

Description copied from interface: DocumentedIOHandler

Indicates whether the serialization of some (short) example table should be added to the user documentation for this handler. Binary formats, or instances for which the Documented.getXmlDescription() method already includes some example output, should return false.

Specified by:

docIncludesExample in interface DocumentedIOHandler

Returns:

true if the user documentation would benefit from the addition of an example serialization

getXmlDescription

public String getXmlDescription()

Description copied from interface: Documented

Returns user-directed documentation in XML format.

The output should be a sequence of one or more <P> elements, using XHTML-like XML. Since rendering may be done in a number of contexts however, use of the full range of XHTML elements is discouraged. Where possible, the content should stick to simple markup such as the elements P, A, UL, OL, LI, DL, DT, DD EM, STRONG, I, B, CODE, TT, PRE.

Specified by:

getXmlDescription in interface Documented

Returns:

XML description of this object