com.softwareag.eda.estore.query.api

Interface ResultStream

All Superinterfaces:

java.lang.AutoCloseable

public interface ResultStream
extends java.lang.AutoCloseable

A table of data representing an Event Store Query result stream, which is usually generated by executing a query against and Event Store. A ResultStream object maintains a cursor pointing to its current row of data. Initially the cursor is positioned before the first row. The next method moves the cursor to the next row, and because it returns false when there are no more rows in the ResultStream object, it can be used in a while loop to iterate through the result set. Methods to move the cursor to various points in the result stream are provided but may or may not be supported by a particular storage technology.

Method Summary

Modifier and Type	Method and Description
void	close() Close the session and free any and all associated resources
boolean	first() Position the cursor at the first element in the result stream
byte[]	getResult() Return the result at the current position in the stream.
boolean	last() Position the cursor at the last element in the result stream
boolean	next() Position the cursor at the next element in the result stream.
boolean	previous() Position the cursor at the previous element in the result stream

Method Detail

next

boolean next()
      throws ResultStreamException

Position the cursor at the next element in the result stream. Note that while first, last previous operations are optional all implementers must provide a next operation.

Returns:

True if the cursor is on a valid row; false if there are no rows in the result set

Throws:

ResultStreamException - on error.

first

boolean first()
       throws ResultStreamException,
              UnsupportedFeatureException

Position the cursor at the first element in the result stream

Returns:

True if the cursor is on a valid row; false if there are no rows in the result set

Throws:

ResultStreamException - on error.

UnsupportedFeatureException - if the feature is unsupported.

last

boolean last()
      throws ResultStreamException,
             UnsupportedFeatureException

Position the cursor at the last element in the result stream

Returns:

True if the cursor is on a valid row; false if there are no rows in the result set

Throws:

ResultStreamException - on error.

UnsupportedFeatureException - if the feature is unsupported.

previous

boolean previous()
          throws ResultStreamException,
                 UnsupportedFeatureException

Position the cursor at the previous element in the result stream

Returns:

True if the cursor is on a valid row; false if there are no rows in the result set

Throws:

ResultStreamException - on error.

UnsupportedFeatureException - if the feature is unsupported.

getResult

byte[] getResult()
          throws ResultStreamException

Return the result at the current position in the stream. All events in the store are stored as JSON. This method will return a JSON document containing objects specified in the select expression.

Returns:

The result stored at the current cursor position;

Throws:

ResultStreamException

close

void close()
    throws ResultStreamException

Close the session and free any and all associated resources

Specified by:

close in interface java.lang.AutoCloseable

Throws:

ResultStreamException