We are using an application that contains a jboss #Service mbean which encapsulates a javax.jms.Connection object.
During startup of the mbean the connection is created by initializing a remote InitialContext, looking up the ConnectionFactory from that context, and creating a connection from that factory:
#Service
public class JMSPublisher extends etcc.... {
private Connection connection;
protected void startService() {
Context ctx = getRemoteInitialContext();
ConnectionFactory connectionFactory = (ConnectionFactory) ctx.lookup("ConnectionFactory");
connection = connectionFactory.createConnection();
}
}
My question is: how long can we be supposed to maintain that connection ? In practise we see that the connection throws a JMSException when we try to create a session on it after an undefined amount of time.
The documentation of Connection tells us that an object represents a socket, so timeouts due to inactivity could be normal. But how can we deal with it without creating new connections for each and every message ?
Your best bet is to have JMSPublisher implement javax.jms.Exception listener. Implement a connect() method which safely acquires a connection on:
startService
onException
A couple of extra points:
For code compression, simply acquire the JMS connection factory via resource injection. The connection factory reference will be resolved before startService is called and will also act as an implicit depends, making the JMS connection factory a dependency for your service.
Have JMSPublisher extend org.jboss.system.ServiceMBeanSupport and implement a token MBean interface (JMSPublisherMBean) that extends org.jboss.system.ServiceMBean. This will ensure that the dependencies are honoured on service start (and stop).
Resource Injected JMS Connection Factory
#Resource(mappedName="ConnectionFactory")
private javax.jms.ConnectionFactory connectionFactory;
private volatile javax.jms.Connection connection;
Modified startService()
public void startService() {
connect();
}
Connection Exception Handler
public void onException(JMSException je) {
connect();
}
*Safe Connection Initializer (adding conn.start()) *
private void synchronized connect() {
log.info("Initializing Connection....");
try {
if(connection!=null) {
try { connection.stop(); } catch (Exception e) {}
try { connection.close(); } catch (Exception e) {}
}
connection = connectionFactory.createConnection();
connection.setExceptionListener(this);
connection.start();
} catch (Exception e) {
log.error("Failed to intialize JMS connection", e);
}
}
This will not automatically take care of other JMS resources allocated through the lost connection, but if other components are using the connection held by this component, you can publish JMX Notifications from JMSPublisher indicating that the connection has been lost and clean up/re-acquire on the notification receipt.
Related
I would like to rollback a transaction for the data in case of errors and at the same time write the error to db.
I can't manage to do with Transactional Annotations.
Following code produces a runtime-error (1/0) and still writes the data into the db. And also writes the data into the error table.
I tried several variations and followed similar questions in StackOverflow but I didn't succeed to do.
Anyone has a hint, how to do?
#Service
public class MyService{
#Transactional(rollbackFor = Exception.class)
public void updateData() {
try{
processAndPersist(); // <- db operation with inserts
int i = 1/0; // <- Runtime error
}catch (Exception e){
persistError()
trackReportError(filename, e.getMessage());
}
}
#Transactional(propagation = Propagation.REQUIRES_NEW)
public void persistError(String message) {
persistError2Db(message); // <- db operation with insert
}
You need the way to throw an exception in updateData() method to rollback a transaction. And you need to not rollback persistError() transaction at the same time.
#Transactional(rollbackFor = Exception.class)
public void updateData() {
try{
processAndPersist(); // <- db operation with inserts
int i = 1/0; // <- Runtime error
}catch (Exception e){
persistError()
trackReportError(filename, e.getMessage());
throw ex; // if throw error here, will not work
}
}
Just throwing an error will not help because persistError() will have the same transaction as updateData() has. Because persistError() is called using this reference, not a reference to a proxy.
Options to solve
Using self reference.
Using self injection Spring self injection for transactions
Move the call of persistError() outside updateData() (and transaction). Remove #Transactional from persistError() (it will not work) and use transaction of Repository in persistError2Db().
Move persistError() to a separate serface. It will be called using a proxy in this case.
Don't use declarative transactions (with #Transactional annotation). Use Programmatic transaction management to set transaction boundaries manually https://docs.spring.io/spring-framework/docs/3.0.0.M3/reference/html/ch11s06.html
Also keep in mind that persistError() can produce error too (and with high probability will do it).
Using self reference
You can use self reference to MyService to have a transaction, because you will be able to call not a method of MyServiceImpl, but a method of Spring proxy.
#Service
public class MyServiceImpl implements MyService {
public void doWork(MyService self) {
DataEntity data = loadData();
try {
self.updateData(data);
} catch (Exception ex) {
log.error("Error for dataId={}", data.getId(), ex);
self.persistError("Error");
trackReportError(filename, ex);
}
}
#Transactional
public void updateData(DataEntity data) {
persist(data); // <- db operation with inserts
}
#Transactional
public void persistError(String message) {
try {
persistError2Db(message); // <- db operation with insert
} catch (Exception ex) {
log.error("Error for message={}", message, ex);
}
}
}
public interface MyService {
void doWork(MyService self);
void updateData(DataEntity data);
void persistError(String message);
}
To use
MyService service = ...;
service.doWork(service);
I am running Netty 4.2 socket communication code with ssl (self signed certificate).
My Problem:
When client tries to connect to server with SSL, server immediately drops the connection. Server triggers channelUnregistered() method immediately.
One point I noticed is, very first time once the server started, client connection holds and works fine. But when client disconnects and try to connect to Server again, it drops the connection immediately.
But without SSL it works fine without any issues.
Client Code:
public Channel initializeNettySocket()
{
group = new NioEventLoopGroup();
try
{
ClientAdapterInitializer clientAdapterInitializer = null;
if (ServerSettings.isUseSSL())
{
// SSLEngine engine = SSLContextFactory.getClientContext().createSSLEngine();
SSLEngine engine = SSLContext.getDefault().createSSLEngine(host,port);
engine.setUseClientMode(true);
clientAdapterInitializer = new ClientAdapterInitializer(engine);
}
else
{
clientAdapterInitializer = new ClientAdapterInitializer();
}
Bootstrap bootstrap = new Bootstrap().group(group).channel(NioSocketChannel.class).handler(clientAdapterInitializer);
channel = bootstrap.connect(host,port).sync().channel();
Thread.sleep(3000);
setChannel(channel);
}
catch (Exception e)
{
System.out.println(e.getMessage());
e.printStackTrace();
}
return channel;
}
public class ClientAdapterInitializer extends ChannelInitializer<SocketChannel>
{
private SSLEngine sslCtx = null;
public ClientAdapterInitializer(SSLEngine sslCtx)
{
this.sslCtx = sslCtx;
}
public ClientAdapterInitializer()
{
}
#Override
protected void initChannel(SocketChannel channel) throws Exception
{
ChannelPipeline pipeline = channel.pipeline();
if (ServerSettings.isUseSSL())
{
// Add SSL handler first to encrypt and decrypt everything.
// In this example, we use a bogus certificate in the server side
// and accept any invalid certificates in the client side.
// You will need something more complicated to identify both
// and server in the real world.
//pipeline.addLast(sslCtx.newHandler(ch.alloc(), SecureChatClient.HOST, SecureChatClient.PORT));
pipeline.addLast(new SslHandler(sslCtx));
}
pipeline.addLast("decoder", new StringDecoder());
pipeline.addLast("encoder", new StringEncoder());
pipeline.addLast("handler", new ClientAdapterHandler());
}
Server side code
public class ServerAdapterInitializer extends ChannelInitializer<SocketChannel>
{
private SSLEngine sslEngine;
public ServerAdapterInitializer(SSLEngine sslEngine)
{
this.sslEngine = sslEngine;
}
public ServerAdapterInitializer()
{
}
#Override
protected void initChannel(SocketChannel channel) throws Exception
{
ChannelPipeline pipeline = channel.pipeline();
if (sslEngine != null)
{
pipeline.addLast(new SslHandler(sslEngine));
}
Listeners.getInstance().getAllListeners().size();
RTReceiverAdapterHandler rtReceiverAdapterHandler = new RTReceiverAdapterHandler();
pipeline.addLast("idleStateHandler", new IdleStateHandler(0, 0, 10)); // add
// with
// name
pipeline.addLast("decoder", new MyStringDecoder(rtReceiverAdapterHandler));
pipeline.addLast("encoder", new StringEncoder());
pipeline.addLast("handler", rtReceiverAdapterHandler);
}
}
public class RTReceiverAdapterHandler extends ChannelInboundHandlerAdapter
{
#Override
public void channelActive(ChannelHandlerContext ctx) throws Exception
{
if (ServerSettings.isUseSSL())
{
// Once session is secured, send a greeting and register the channel
// to the global channel
// list so the channel received the messages from others.
ctx.pipeline().get(SslHandler.class).handshakeFuture().addListener(new GenericFutureListener<Future<Channel>>()
{
#Override
public void operationComplete(Future<Channel> future) throws Exception
{
ctx.writeAndFlush("Welcome!\n");
ctx.writeAndFlush("Your session is protected by " + ctx.pipeline().get(SslHandler.class).engine().getSession().getCipherSuite()
+ " cipher suite.\n");
channels.add(ctx.channel());
}
});
}
else
{
super.channelActive(ctx);
}
}
}
The problem was not with the code at all. We have nginx web server configured with SSL before my application. This entry in nginx 'ssl_ciphers AES256+EECDH:AES256+EDH:!aNULL;' was the culprit which was not allowing to access the netty server.
I commented the above entry in ngnix and my problem was resolved.
javax.microedition.io.ConnectionNotFoundException: error 10061 in socket::open
I have this error with j2me - in execution.
I tried searching, but it didn't help.
Code:
Connector.open("socket://127.0.0.1:7777")
According to ConnectionNotFoundException documentation "This class is used to signal that a connection target cannot be found, or the protocol type is not supported".
socket is a supported protocol, so the connection target cannot be found. Be sure that 127.0.0.1:7777 is up, running and that is does support receiving a Socket connection.
You may try below Java code:
public class Server {
static boolean done = false;
public static void main(String[] args) {
try {
ServerSocket server = new ServerSocket(7777);
while (!done) {
final Socket socket = server.accept();
new Thread() {
public void run() {
treatSocket(socket);
}
}.start();
}
} catch (IOException e) {
e.printStackTrace();
}
}
static void treatSocket(Socket socket) {
// treat socket data
}
}
I'm using BoneCP for connection pooling jdbc connections to my mysql database. I'm using the bonecp example in my REST application.
If every REST request is opening and closing the connection pool, doesn't this defeat the point of connection pooling in the first place?
Here is the code:
public class ExampleJDBC {
/** Start test
* #param args none expected.
*/
public static void main(String[] args) {
BoneCP connectionPool = null;
Connection connection = null;
try {
// load the database driver (make sure this is in your classpath!)
Class.forName("org.hsqldb.jdbcDriver");
} catch (Exception e) {
e.printStackTrace();
return;
}
try {
// setup the connection pool
BoneCPConfig config = new BoneCPConfig();
config.setJdbcUrl("jdbc:hsqldb:mem:test"); // jdbc url specific to your database, eg jdbc:mysql://127.0.0.1/yourdb
config.setUsername("sa");
config.setPassword("");
config.setMinConnectionsPerPartition(5);
config.setMaxConnectionsPerPartition(10);
config.setPartitionCount(1);
connectionPool = new BoneCP(config); // setup the connection pool
connection = connectionPool.getConnection(); // fetch a connection
if (connection != null){
System.out.println("Connection successful!");
Statement stmt = connection.createStatement();
ResultSet rs = stmt.executeQuery("SELECT 1 FROM INFORMATION_SCHEMA.SYSTEM_USERS"); // do something with the connection.
while(rs.next()){
System.out.println(rs.getString(1)); // should print out "1"'
}
}
connectionPool.shutdown(); // shutdown connection pool.
} catch (SQLException e) {
e.printStackTrace();
} finally {
if (connection != null) {
try {
connection.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}
}
Yes, it would defeat the purpose to open or close the connection pool more than once in the (typical) lifecycle of your application. You should fetch a connection from the pre-established pool each time instead.
I am using EJB 3.0 timer.When my Timeout method gets invoked,I use JPA to insert a record in one of the table.I use JPA to persist the data.I defined the persist code in a Stateless Session Bean and invoked the local interface inside my timeout method.I get the following exception when the thread comes out of the timeout method:
javax.transaction.xa.XAException: JDBC driver does not support XA, hence cannot be a participant in two-phase commit.
To force this participation, set the GlobalTransactionsProtocol attribute to LoggingLastResource (recommended) or EmulateTwoPhaseCommit for the Data Source
Our DB does not support XA transaction.We use WL 10.3.1.Here is the code which i do :
#EJB
private MyejbLocal myejbLocal
#Timeout
public void callEjb(timer) {
try {
myejbLocal .store();
} catch (EntityExistsException e) {
e.getMessage();
} catch (Exception ex) {
ex.getCause();
}
}
Here is my implementation:
#Override
public void Store() {
try {
Mytable mytable= new Mytable (new Date());
persist(mytable);
} catch (EntityExistsException e) {
e.getMessage();
} catch (Exception ex) {
ex.getCause();
}
}
I don't call flush() method.
Please let me know if I have missed any?
I also faced the same issue. You need to keep your JPA entity operation in a separate session bean and it will work.
http://prasunejohn.blogspot.in/2014/02/understanding-ejb-timer-service-31.html