Package com.mckoi.database.jdbcserver

Class StreamJDBCServerConnection

java.lang.Object

com.mckoi.database.jdbcserver.JDBCProcessor

com.mckoi.database.jdbcserver.StreamJDBCServerConnection

All Implemented Interfaces:

ProtocolConstants, ServerConnection

Direct Known Subclasses:

TCPJDBCServerConnection

abstract class StreamJDBCServerConnection
extends JDBCProcessor
implements ServerConnection

A generic JDBC stream protocol server that reads JDBC commands from a stream from each connection and dispatches the commands appropriately.

Field Summary

Fields

Modifier and Type	Field	Description
private static int	INPUT_BUFFER_SIZE	The size in bytes of the buffer used for reading information from the input stream from the client.
private LengthMarkedBufferedInputStream	marked_input	The LengthMarkedBufferedInputStream we use to poll for commands from the client.
private java.io.DataOutputStream	out	The output stream to the client formatted as a DataOutputStream.
private static int	OUTPUT_BUFFER_SIZE	The size in bytes of the buffer used for writing information onto the output stream to the client.

Fields inherited from interface com.mckoi.database.jdbc.ProtocolConstants

ACKNOWLEDGEMENT, AUTHENTICATION_ERROR, CLOSE, DATABASE_EVENT, DISPOSE_RESULT, DISPOSE_STREAMABLE_OBJECT, EXCEPTION, FAILED, PING, PUSH_STREAMABLE_OBJECT_PART, QUERY, RESULT_SECTION, SERVER_REQUEST, STREAMABLE_OBJECT_SECTION, SUCCESS, USER_AUTHENTICATION_FAILED, USER_AUTHENTICATION_PASSED

Constructor Summary

Constructors

Constructor	Description
StreamJDBCServerConnection(DatabaseInterface db_interface, java.io.InputStream in, java.io.OutputStream out, DebugLogger logger)	Sets up the protocol connection.

Method Summary

Modifier and Type	Method	Description
void	blockForRequest()	Block waiting for a complete command to become available.
void	ping()	Pings the client to check it's still alive.
void	processRequest()	Processes a request from this connection.
boolean	requestPending()	Inspects the input stream and determines in there's a command pending to be processed.
void	sendEvent(byte[] event_msg)	Sends an event to the client.

Methods inherited from class com.mckoi.database.jdbcserver.JDBCProcessor

close, dispose, finalize, getState, isClosed, printByteArray, processJDBCCommand

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.mckoi.database.jdbcserver.ServerConnection

close

Field Detail

OUTPUT_BUFFER_SIZE

private static final int OUTPUT_BUFFER_SIZE

The size in bytes of the buffer used for writing information onto the output stream to the client.

See Also:

Constant Field Values

INPUT_BUFFER_SIZE

private static final int INPUT_BUFFER_SIZE

The size in bytes of the buffer used for reading information from the input stream from the client.

See Also:

Constant Field Values

marked_input

private LengthMarkedBufferedInputStream marked_input

The LengthMarkedBufferedInputStream we use to poll for commands from the client.

out

private java.io.DataOutputStream out

The output stream to the client formatted as a DataOutputStream.

Constructor Detail

StreamJDBCServerConnection

StreamJDBCServerConnection(DatabaseInterface db_interface,
                           java.io.InputStream in,
                           java.io.OutputStream out,
                           DebugLogger logger)
                    throws java.io.IOException

Sets up the protocol connection.

Throws:

java.io.IOException

Method Detail

sendEvent

public void sendEvent(byte[] event_msg)
               throws java.io.IOException

Description copied from class: JDBCProcessor

Sends an event to the client. This is used to notify the client of trigger events, etc.

SECURITY ISSUE: This is always invoked by the DatabaseDispatcher. We have to be careful that this method isn't allowed to block. Otherwise the DatabaseDispatcher thread will be out of operation. Unfortunately assuring this may not be possible until Java has non-blocking IO, or we use datagrams for transmission. I know for sure that the TCP implementation is vunrable. If the client doesn't 'read' what we are sending then this'll block when the buffers become full.

Specified by:

sendEvent in class JDBCProcessor

Throws:

java.io.IOException

requestPending

public boolean requestPending()
                       throws java.io.IOException

Inspects the input stream and determines in there's a command pending to be processed.

Specified by:

requestPending in interface ServerConnection

Throws:

java.io.IOException

processRequest

public void processRequest()
                    throws java.io.IOException

Processes a request from this connection.

Specified by:

processRequest in interface ServerConnection

Throws:

java.io.IOException

blockForRequest

public void blockForRequest()
                     throws java.io.IOException

Block waiting for a complete command to become available.

Specified by:

blockForRequest in interface ServerConnection

Throws:

java.io.IOException

ping

public void ping()
          throws java.io.IOException

Pings the client to check it's still alive.

Specified by:

ping in interface ServerConnection

Throws:

java.io.IOException