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 efficienly across the network. Server's direct
descendent, WebServer, handles HTTP protocol connections exclusively,
allowing HSQL protocol to be tunneled 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:
- Upon construction, a Server object is assigned a set of default
properties.
- If it exists, properties are loaded from a file named
'server.properties' in the present working directory.
- 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 |
+----------------+-------------+----------+------------------------------|
| -? | -- | -- | 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 |
+----------------+-------------+----------+------------------------------+
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:
- true when a Server is started directly from the start()
method.
- 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 intance
is started as part of a larger framework.
Replaces original Hypersonic source of the same name.
checkRunning
public void checkRunning(boolean running)
throws RuntimeException
Checks if this Server object is or is not running and throws if the
current state does not match the specified value.
running
- if true, ensure the server is running, else ensure the
server is not running
getAddress
public String getAddress()
Retrieves, in string form, this server's host address.
- 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.
index
- the index of the url alias upon which to reportasconfigured
- if true, report the configured value, else
the live value
- 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.
index
- the index of the uri upon which to reportasconfigured
- if true, report the configured value, else
the live value
- 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).
- the name of the web page served when no page is specified
getErrWriter
public PrintWriter getErrWriter()
Retrieves the PrintWriter to which server errors are printed.
- the PrintWriter to which server errors are printed.
getHelpString
public String getHelpString()
Retrieves a String object describing the command line and
properties options for this Server.
- the command line and properties options help for this Server
getLogWriter
public PrintWriter getLogWriter()
Retrieves the PrintWriter to which server messages are printed.
- the PrintWriter to which server messages are printed.
getPort
public int getPort()
Retrieves this server's host port.
getProductName
public String getProductName()
Retrieves this server's product name.
Typically, this will be something like: "HSQLDB xxx server".
- 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.
- the product version of the server
getProtocol
public String getProtocol()
Retrieves a string respresentaion of the network protocol
this server offers, typically one of 'HTTP', HTTPS', 'HSQL' or 'HSQLS'.
- string respresentation of this server's protocol
getServerError
public Throwable getServerError()
Retrieves a Throwable indicating the last server error, if any.
- a Throwable indicating the last server error
getServerId
public String getServerId()
Retrieves a String identifying this Server object.
- 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:
- ServerProperties.SERVER_STATE_ONLINE (1)
- ServerProperties.SERVER_STATE_OPENING (4)
- ServerProperties.SERVER_STATE_CLOSING (8)
- ServerProperties.SERVER_STATE_SHUTDOWN (16)
- 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.
- 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.
- the root context (directory) from which web content is served
handleConnection
public void handleConnection(Socket s)
Assigns the specified socket to a new conection handler and
starts the handler in a new Thread.
s
- the socket to connect
isNoSystemExit
public boolean isNoSystemExit()
Retrieves whether this server calls System.exit() when shutdown.
- true if this server does not call System.exit()
isRestartOnShutdown
public boolean isRestartOnShutdown()
Retrieves whether this server restarts on shutdown.
- true this server restarts on shutdown
isSilent
public boolean isSilent()
Retrieves whether silent mode operation was requested in
the server properties.
- 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.
- 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.
- true if tracing is on (JDBC trace messages to system out)
main
public static void main(String[] args)
Creates and starts a new Server.
Allows starting a Server via the command line interface.
args
- the command line arguments for the Server instance
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.
path
- the path of the desired properties file, without the
'.properties' file extension
- true if the indicated file was read sucessfully, else false
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.
s
- semicolon-delimited key=value pair string,
e.g. k1=v1;k2=v2;k3=v3...
setAddress
public void setAddress(String address)
throws RuntimeException
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.
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.
setDatabaseName
public void setDatabaseName(int index,
String name)
throws RuntimeException
Sets the external name (url alias) of the i'th hosted database.
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)
throws RuntimeException
Sets the path of the hosted database.
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.
file
- the name of the web page served when no page is specified
setErrWriter
public void setErrWriter(PrintWriter pw)
Sets the PrintWriter to which server errors are logged.
Setting this attribute to null disables server error logging
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
pw
- the PrintWriter to which server messages are logged
setNoSystemExit
public void setNoSystemExit(boolean noExit)
Sets whether this server calls System.exit() when shutdown.
noExit
- if true, System.exit() will not be called.
setPort
public void setPort(int port)
throws RuntimeException
Sets the server listen port.
port
- the port at which this server listens
setProperties
public void setProperties(org.hsqldb.persist.HsqlProperties p)
Sets server properties using the specified properties object
p
- The object containing properties to set
setRestartOnShutdown
public void setRestartOnShutdown(boolean restart)
Sets whether this server restarts on shutdown.
restart
- if true, this server restarts on shutdown
setSilent
public void setSilent(boolean silent)
Sets silent mode operation
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
tls
- true for secure sockets, else false
setTrace
public void setTrace(boolean trace)
Sets whether trace messages go to System.out or the
DriverManger PrintStream/PrintWriter, if any.
trace
- if true, route JDBC trace messages to System.out
setWebRoot
public void setWebRoot(String root)
Sets the path of the root directory from which web content is served.
root
- the root (context) directory from which web content
is served
shutdown
public void shutdown()
External method to shut down this server.
signalCloseAllServerConnections
public void signalCloseAllServerConnections()
Closes all connections to this Server.
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.
- 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.
- the server state noted at entry to this method