org.hsqldb.server

Class Server

java.lang.Object

org.hsqldb.server.Server

All Implemented Interfaces:

org.hsqldb.lib.Notified, org.hsqldb.server.HsqlSocketRequestHandler

Direct Known Subclasses:

WebServer

public class Server
extends Object
implements org.hsqldb.server.HsqlSocketRequestHandler, org.hsqldb.lib.Notified

The HSQLDB HSQL protocol network database server.

A Server object acts as a network database server and is one way of using the client-server mode of HSQLDB Database Engine. Instances of this class handle native HSQL protocol connections exclusively, allowing database queries to be performed efficiently across the network. Server's direct descendant, WebServer, handles HTTP protocol connections exclusively, allowing HSQL protocol to be tunnelled over HTTP to avoid sandbox and firewall issues, albeit less efficiently.

There are a number of ways to configure and start a Server instance.

When started from the command line or programatically via the main(String[]) method, configuration occurs in three phases, with later phases overriding properties set by previous phases:

1. Upon construction, a Server object is assigned a set of default properties.
2. If it exists, properties are loaded from a file named 'server.properties' in the present working directory.
3. The command line arguments (alternatively, the String[] passed to main()) are parsed and used to further configure the Server's properties.

From the command line, the options are as follows:

 +-----------------+-------------+----------+------------------------------+
 |    OPTION       |    TYPE     | DEFAULT  |         DESCRIPTION          |
 +-----------------+-------------+----------+------------------------------|
 | --help          |             |          | prints this message          |
 | --address       | name|number | any      | server inet address          |
 | --port          | number      | 9001/544 | port at which server listens |
 | --database.i    | [type]spec  | 0=test   | path of database i           |
 | --dbname.i      | alias       |          | url alias for database i     |
 | --silent        | true|false  | true     | false => display all queries |
 | --trace         | true|false  | false    | display JDBC trace messages  |
 | --tls           | true|false  | false    | TLS/SSL (secure) sockets     |
 | --no_system_exit| true|false  | false    | do not issue System.exit()   |
 | --remote_open   | true|false  | false    | can open databases remotely  |
 | --props         | filepath    |          | file path of properties file |
 +-----------------+-------------+----------+------------------------------+
 

The database.i and dbname.i options need further explanation:

• Multiple databases can be served by each instance of the Server. The value of i is currently limited to the range 0..9, allowing up to 10 different databases. Any number is this range can be used.
• The value assigned to database.i is interpreted using the format '[type]spec', where the optional type component is one of 'file:', 'res:' or 'mem:' and the spec component is interpreted in the context of the type component.

  If omitted, the type component is taken to be 'file:'.

  A full description of how '[type]spec' values are interpreted appears in the overview for JDBCConnection.

• The value assigned to dbname.i is taken to be the key used to look up the desired database instance and thus corresponds to the <alias> component of the HSQLDB HSQL protocol database connection url: 'jdbc:hsqldb:hsql[s]://host[port][/<alias>]'.
• The value of database.0 is special. If dbname.0 is not specified, then this defaults to an empty string and a connection is made to database.0 path when the <alias> component of an HSQLDB HSQL protocol database connection url is omitted. If a database key/value pair is found in the properties when the main method is called, this pair is supersedes the database.0 setting

  This behaviour allows the previous database connection url format to work with essentially unchanged semantics.

• When the remote_open property is true, a connection attempt to an unopened database results in the database being opened. The URL for connection should include the property filepath to specify the path. 'jdbc:hsqldb:hsql[s]://host[port]/<alias>;filepath=hsqldb:file:<database path>'. the given alias and filepath value will be associated together. The database user and password to start this connection must be valid. If this form of connection is used again, after the database has been opened, the filepath property is ignored.
• Once an alias such as "mydb" has been associated with a path, it cannot be reassigned to a different path.
• If a database is closed with the SHUTDOWN command, its alias is removed. It is then possible to connect to this database again with a different (or the same) alias.
• If the same database is connected to via two different aliases, and then one of the is closed with the SHUTDOWN command, the other is also closed.

From the 'server.properties' file, options can be set similarly, using a slightly different format.

Here is an example 'server.properties' file:

 server.port=9001
 server.database.0=test
 server.dbname.0=...
 ...
 server.database.n=...
 server.dbname.n=...
 server.silent=true
 

Starting with 1.7.2, Server has been refactored to become a simple JavaBean with non-blocking start() and stop() service methods. It is possible to configure a Server instance through the JavaBean API as well, but this part of the public interface is still under review and will not be finalized or documented fully until the final 1.7.2 release.

Note:

The 'no_system_exit' property is of particular interest.

If a Server instance is to run embedded in, say, an application server, such as when the JDBCDataSource or HsqlServerFactory classes are used, it is typically necessary to avoid calling System.exit() when the Server instance shuts down.

By default, 'no_system_exit' is set:

1. true when a Server is started directly from the start() method.
2. false when a Server is started from the main(String[]) method.

These values are natural to their context because the first case allows the JVM to exit by default on Server shutdown when a Server instance is started from a command line environment, whereas the second case prevents a typically unwanted JVM exit on Server shutdown when a Server instance is started as part of a larger framework.

Since:

1.7.2

Author:

Fred Toussi (fredt@users dot sourceforge.net)

Constructor Summary

Constructors

Constructor and Description
Server() Creates a new Server instance handling HSQL protocol connections.

Method Summary

Modifier and Type	Method and Description
void	checkRunning(boolean running) Checks if this Server object is or is not running and throws if the current state does not match the specified value.
String	getAddress() Retrieves, in string form, this server's host address.
String	getDatabaseName(int index, boolean asconfigured) Retrieves the url alias (network name) of the i'th database that this Server hosts.
String	getDatabasePath(int index, boolean asconfigured) Retrieves the HSQLDB path descriptor (uri) of the i'th Database that this Server hosts.
String	getDatabaseType(int index)
String	getDefaultWebPage() Retrieves the name of the web page served when no page is specified.
PrintWriter	getErrWriter() Retrieves the PrintWriter to which server errors are printed.
String	getHelpString() Retrieves a String object describing the command line and properties options for this Server.
PrintWriter	getLogWriter() Retrieves the PrintWriter to which server messages are printed.
int	getPort() Retrieves this server's host port.
String	getProductName() Retrieves this server's product name.
String	getProductVersion() Retrieves the server's product version, as a String.
String	getProtocol() Retrieves a string resresentaion of the network protocol this server offers, typically one of 'HTTP', HTTPS', 'HSQL' or 'HSQLS'.
Throwable	getServerError() Retrieves a Throwable indicating the last server error, if any.
String	getServerId() Retrieves a String identifying this Server object.
Thread	getServerThread() Returns thread object for "HSQLDB Server" thread
int	getState() Retrieves current state of this server in numerically coded form.
String	getStateDescriptor() Retrieves a character sequence describing this server's current state, including the message of the last exception, if there is one and it is still in context.
String	getWebRoot() Retrieves the root context (directory) from which web content is served.
void	handleConnection(Socket s) Assigns the specified socket to a new connection handler and starts the handler in a new Thread.
boolean	isNoSystemExit() Retrieves whether this server calls System.exit() when shutdown.
boolean	isNotRunning() Returns true if this server is not running
boolean	isRestartOnShutdown() Retrieves whether this server restarts on shutdown.
boolean	isSilent() Retrieves whether silent mode operation was requested in the server properties.
boolean	isTls() Retrieves whether the use of secure sockets was requested in the server properties.
boolean	isTrace() Retrieves whether JDBC trace messages are to go to System.out or the DriverManger PrintStream/PrintWriter, if any.
static void	main(String[] args) Creates and starts a new Server.
void	notify(int id) This is called from org.hsqldb.DatabaseManager when a database is shutdown.
boolean	putPropertiesFromFile(String path) Attempts to put properties from the file with the specified path.
boolean	putPropertiesFromFile(String path, String extension) Attempts to put properties from the file with given extension.
void	putPropertiesFromString(String s) Puts properties from the supplied string argument.
void	setAddress(String address) Sets the InetAddress with which this server's ServerSocket will be constructed.
void	setDaemon(boolean daemon) Sets whether server thread is a daemon.
void	setDatabaseName(int index, String name) Sets the external name (url alias) of the i'th hosted database.
void	setDatabasePath(int index, String path) Sets the path of the hosted database.
void	setDefaultWebPage(String file) Sets the name of the web page served when no page is specified.
void	setErrWriter(PrintWriter pw) Sets the PrintWriter to which server errors are logged.
void	setLogWriter(PrintWriter pw) Sets the PrintWriter to which server messages are logged.
void	setNoSystemExit(boolean noExit) Sets whether this server calls System.exit() when shutdown.
void	setPort(int port) Sets the server listen port.
void	setProperties(org.hsqldb.persist.HsqlProperties props) Sets server properties using the specified properties object
void	setRestartOnShutdown(boolean restart) Sets whether this server restarts on shutdown.
void	setSilent(boolean silent) Sets silent mode operation
void	setTls(boolean tls) Sets whether to use secure sockets
void	setTrace(boolean trace) Sets whether trace messages go to System.out or the DriverManger PrintStream/PrintWriter, if any.
void	setWebRoot(String root) Sets the path of the root directory from which web content is served.
void	shutdown() External method to shut down this server.
void	shutdownCatalogs(int shutdownMode) Shuts down all the database served by this server.
void	shutdownWithCatalogs(int shutdownMode) Shuts down this server and all the database served by this server.
void	signalCloseAllServerConnections() Closes all connections to this Server.
int	start() Starts this server synchronously.
int	stop() Stops this server asynchronously.

Methods inherited from class java.lang.Object

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

Constructor Detail

Server

public Server()

Creates a new Server instance handling HSQL protocol connections.

Method Detail

getServerThread

public Thread getServerThread()

Returns thread object for "HSQLDB Server" thread

Returns:

thread

checkRunning

public void checkRunning(boolean running)

Checks if this Server object is or is not running and throws if the current state does not match the specified value.

Parameters:

running - if true, ensure the server is running, else ensure the server is not running

Throws:

org.hsqldb.HsqlException - if the supplied value does not match the current running status

isNotRunning

public boolean isNotRunning()

Returns true if this server is not running

Returns:

boolean

signalCloseAllServerConnections

public void signalCloseAllServerConnections()

Closes all connections to this Server.

Specified by:

signalCloseAllServerConnections in interface org.hsqldb.server.HsqlSocketRequestHandler

getAddress

public String getAddress()

Retrieves, in string form, this server's host address.

Returns:

this server's host address

getDatabaseName

public String getDatabaseName(int index,
                              boolean asconfigured)

Retrieves the url alias (network name) of the i'th database that this Server hosts.

Parameters:

index - the index of the url alias upon which to report

asconfigured - if true, report the configured value, else the live value

Returns:

the url alias component of the i'th database that this Server hosts, or null if no such name exists.

getDatabasePath

public String getDatabasePath(int index,
                              boolean asconfigured)

Retrieves the HSQLDB path descriptor (uri) of the i'th Database that this Server hosts.

Parameters:

index - the index of the uri upon which to report

asconfigured - if true, report the configured value, else the live value

Returns:

the HSQLDB database path descriptor of the i'th database that this Server hosts, or null if no such path descriptor exists

getDatabaseType

public String getDatabaseType(int index)

getDefaultWebPage

public String getDefaultWebPage()

Retrieves the name of the web page served when no page is specified. This attribute is relevant only when server protocol is HTTP(S).

Returns:

the name of the web page served when no page is specified

getHelpString

public String getHelpString()

Retrieves a String object describing the command line and properties options for this Server.

Returns:

the command line and properties options help for this Server

getErrWriter

public PrintWriter getErrWriter()

Retrieves the PrintWriter to which server errors are printed.

Returns:

the PrintWriter to which server errors are printed.

getLogWriter

public PrintWriter getLogWriter()

Retrieves the PrintWriter to which server messages are printed.

Returns:

the PrintWriter to which server messages are printed.

getPort

public int getPort()

Retrieves this server's host port.

Returns:

this server's host port

getProductName

public String getProductName()

Retrieves this server's product name.

Typically, this will be something like: "HSQLDB xxx server".

Returns:

the product name of this server

getProductVersion

public String getProductVersion()

Retrieves the server's product version, as a String.

Typically, this will be something like: "1.x.x" or "2.x.x" and so on.

Returns:

the product version of the server

getProtocol

public String getProtocol()

Retrieves a string resresentaion of the network protocol this server offers, typically one of 'HTTP', HTTPS', 'HSQL' or 'HSQLS'.

Returns:

string representation of this server's protocol

getServerError

public Throwable getServerError()

Retrieves a Throwable indicating the last server error, if any.

Returns:

a Throwable indicating the last server error

getServerId

public String getServerId()

Retrieves a String identifying this Server object.

Returns:

a String identifying this Server object

getState

public int getState()

Retrieves current state of this server in numerically coded form.

Typically, this will be one of:

1. ServerProperties.SERVER_STATE_ONLINE (1)
2. ServerProperties.SERVER_STATE_OPENING (4)
3. ServerProperties.SERVER_STATE_CLOSING (8)
4. ServerProperties.SERVER_STATE_SHUTDOWN (16)

Returns:

this server's state code.

getStateDescriptor

public String getStateDescriptor()

Retrieves a character sequence describing this server's current state, including the message of the last exception, if there is one and it is still in context.

Returns:

this server's state represented as a character sequence.

getWebRoot

public String getWebRoot()

Retrieves the root context (directory) from which web content is served. This property is relevant only when the server protocol is HTTP(S). Although unlikely, it may be that in the future other contexts, such as jar urls may be supported, so that pages can be served from the contents of a jar or from the JVM class path.

Returns:

the root context (directory) from which web content is served

handleConnection

public void handleConnection(Socket s)

Assigns the specified socket to a new connection handler and starts the handler in a new Thread.

Specified by:

handleConnection in interface org.hsqldb.server.HsqlSocketRequestHandler

Parameters:

s - the socket to connect

isNoSystemExit

public boolean isNoSystemExit()

Retrieves whether this server calls System.exit() when shutdown.

Returns:

true if this server does not call System.exit()

isRestartOnShutdown

public boolean isRestartOnShutdown()

Retrieves whether this server restarts on shutdown.

Returns:

true this server restarts on shutdown

isSilent

public boolean isSilent()

Retrieves whether silent mode operation was requested in the server properties.

Returns:

if true, silent mode was requested, else trace messages are to be printed

isTls

public boolean isTls()

Retrieves whether the use of secure sockets was requested in the server properties.

Returns:

if true, secure sockets are requested, else not

isTrace

public boolean isTrace()

Retrieves whether JDBC trace messages are to go to System.out or the DriverManger PrintStream/PrintWriter, if any.

Returns:

true if tracing is on (JDBC trace messages to system out)

putPropertiesFromFile

public boolean putPropertiesFromFile(String path)

Attempts to put properties from the file with the specified path. The file extension '.properties' is implicit and should not be included in the path specification.

Parameters:

path - the path of the desired properties file, without the '.properties' file extension

Returns:

true if the indicated file was read successfully, else false

Throws:

org.hsqldb.HsqlException - if this server is running

putPropertiesFromFile

public boolean putPropertiesFromFile(String path,
                                     String extension)

Attempts to put properties from the file with given extension.

Parameters:

path - the path of the desired properties file.

extension - extension to add to path

Returns:

true if the indicated file was read successfully, else false

Throws:

org.hsqldb.HsqlException - if this server is running

putPropertiesFromString

public void putPropertiesFromString(String s)

Puts properties from the supplied string argument. The relevant key value pairs are the same as those for the (web)server.properties file format, except that the 'server.' prefix should not be specified.

Parameters:

s - semicolon-delimited key=value pair string, e.g. silent=false;port=8080;...

Throws:

org.hsqldb.HsqlException - if this server is running

setAddress

public void setAddress(String address)

Sets the InetAddress with which this server's ServerSocket will be constructed. A null or empty string or the special value "0.0.0.0" can be used to bypass explicit selection, causing the ServerSocket to be constructed without specifying an InetAddress.

Parameters:

address - A string representing the desired InetAddress as would be retrieved by InetAddres.getByName(), or a null or empty string or "0.0.0.0" to signify that the server socket should be constructed using the signature that does not specify the InetAddress.

Throws:

org.hsqldb.HsqlException - if this server is running

setDatabaseName

public void setDatabaseName(int index,
                            String name)

Sets the external name (url alias) of the i'th hosted database.

Parameters:

index - int

name - external name (url alias) of the i'th HSQLDB database instance this server is to host.

setDatabasePath

public void setDatabasePath(int index,
                            String path)

Sets the path of the hosted database. The path always starts with the catalog type. Examples of the path include: "file:mydir/mydb", "mem:mymemdb", "res:org/mydomain/mydbs/settingsdb".

Parameters:

index - int

path - The path of the i'th HSQLDB database instance this server is to host.

setDefaultWebPage

public void setDefaultWebPage(String file)

Sets the name of the web page served when no page is specified.

Parameters:

file - the name of the web page served when no page is specified

setPort

public void setPort(int port)

Sets the server listen port.

Parameters:

port - the port at which this server listens

setErrWriter

public void setErrWriter(PrintWriter pw)

Sets the PrintWriter to which server errors are logged.

Setting this attribute to null disables server error logging

Parameters:

pw - the PrintWriter to which server messages are logged

setLogWriter

public void setLogWriter(PrintWriter pw)

Sets the PrintWriter to which server messages are logged.

Setting this attribute to null disables server message logging

Parameters:

pw - the PrintWriter to which server messages are logged

setNoSystemExit

public void setNoSystemExit(boolean noExit)

Sets whether this server calls System.exit() when shutdown.

Parameters:

noExit - if true, System.exit() will not be called.

setRestartOnShutdown

public void setRestartOnShutdown(boolean restart)

Sets whether this server restarts on shutdown.

Parameters:

restart - if true, this server restarts on shutdown

setSilent

public void setSilent(boolean silent)

Sets silent mode operation

Parameters:

silent - if true, then silent mode, else trace messages are to be printed

setTls

public void setTls(boolean tls)

Sets whether to use secure sockets

Parameters:

tls - true for secure sockets, else false

Throws:

org.hsqldb.HsqlException - if this server is running

setTrace

public void setTrace(boolean trace)

Sets whether trace messages go to System.out or the DriverManger PrintStream/PrintWriter, if any.

Parameters:

trace - if true, route JDBC trace messages to System.out

setDaemon

public void setDaemon(boolean daemon)

Sets whether server thread is a daemon. Used before starting. The default is false.

Parameters:

daemon - if true, start the thread as a daemon thread

setWebRoot

public void setWebRoot(String root)

Sets the path of the root directory from which web content is served.

Parameters:

root - the root (context) directory from which web content is served

setProperties

public void setProperties(org.hsqldb.persist.HsqlProperties props)
                   throws IOException,
                          ServerAcl.AclFormatException

Sets server properties using the specified properties object

Parameters:

props - The object containing properties to set

Throws:

ServerAcl.AclFormatException - ACL list was requested but problem loading ACL.

IOException - ACL list was requested but I/O problem loading ACL.

start

public int start()

Starts this server synchronously.

This method waits for current state to change from SERVER_STATE_OPENNING. In order to discover the success or failure of this operation, server state must be polled or a subclass of Server must be used that overrides the setState method to provide state change notification.

Returns:

the server state noted at entry to this method

stop

public int stop()

Stops this server asynchronously.

This method returns immediately, regardless of current state. In order to discover the success or failure of this operation, server state must be polled or a subclass of Server must be used that overrides the setState method to provide state change notification.

Returns:

the server state noted at entry to this method

notify

public final void notify(int id)

This is called from org.hsqldb.DatabaseManager when a database is shutdown. This shuts the server down if it is the last database

Specified by:

notify in interface org.hsqldb.lib.Notified

Parameters:

id - database id

shutdownCatalogs

public void shutdownCatalogs(int shutdownMode)

Shuts down all the database served by this server. As a consequence, this server and any other server that is serving a subset of the databases will be shutdown, unless the server was started with server.remote_open property. The shutdownMode must be one of:

• org.hsqldb.Database.CLOSEMODE_IMMEDIATELY
• org.hsqldb.Database.CLOSEMODE_NORMAL
• org.hsqldb.Database.CLOSEMODE_COMPACT
• org.hsqldb.Database.CLOSEMODE_SCRIPT

Parameters:

shutdownMode - a value between 0-4, usually 0 or 1.

shutdownWithCatalogs

public void shutdownWithCatalogs(int shutdownMode)

Shuts down this server and all the database served by this server. As a consequence, any other server that is serving a subset of the databases will be shutdown, unless the server was started with server.remote_open property. The shutdownMode must be one of:

• org.hsqldb.Database.CLOSEMODE_IMMEDIATELY
• org.hsqldb.Database.CLOSEMODE_NORMAL
• org.hsqldb.Database.CLOSEMODE_COMPACT
• org.hsqldb.Database.CLOSEMODE_SCRIPT

Parameters:

shutdownMode - a value between 0-4, usually 0 or 1.

shutdown

public void shutdown()

External method to shut down this server.

main

public static void main(String[] args)

Creates and starts a new Server.

Allows starting a Server via the command line interface.

Parameters:

args - the command line arguments for the Server instance