Category Archives: Tomcat 6

Configure Apache ActiveMQ with Tomcat 6

Hi,

Apache ActiveMQ:

Apache ActiveMQ is an open source (Apache 2.0 licensed) message broker which fully implements the Java Message Service 1.1 (JMS). It provides “Enterprise Features”[1] like clustering, multiple message stores, and ability to use any database as a JMS persistence provider besides VM, cache, and journal persist-ency. Below is the list of some other Main features.  ActiveMQ is often a good recommendation for SOA infrastructure projects.

Few Main Features:
1.  full support for the Enterprise Integration Patterns both in the JMS client and the Message Broker
2.  OpenWire for high performance clients in Java, C, C++, C#
3. Supports very fast persistence using JDBC along with a high performance journal
4. Fully supports JMS 1.1 and J2EE 1.4 with support for transient, persistent, transactional and XA messaging

Connectivity:
Apache ActiveMQ is designed to support a large number if Cross Language Clients, speak a wide range of Protocols and be usable in a wide variety of Containers in addition to being usable in a stand alone Java SE platform. Read more information in the below URL.
http://activemq.apache.org/connectivity.html

Integration with Tomcat 6:

Install the ActiveMQ related jars into the [TOMCAT_ROOT]/lib/
activemq-all-5.4.0.jar
commons-logging-1.1.jar

Step 1:

Open the [TOMCAT_ROOT]/conf/server.xml file and add the below resource to the GlobalNamingResources.


<GlobalNamingResources>

<Resource  name=”jms/ConnectionFactory” auth=”Container” type=”org.apache.activemq.ActiveMQConnectionFactory” description=”JMS Connection Factory” factory=”org.apache.activemq.jndi.JNDIReferenceFactory” brokerURL=”tcp://localhost:61616″ brokerName=”ActiveMQBroker” useEmbeddedBroker=”false”/>

<Resource name=”jms/topic/MyTopic” auth=”Container” type=”org.apache.activemq.command.ActiveMQTopic” factory=”org.apache.activemq.jndi.JNDIReferenceFactory” physicalName=”APP.JMS.TOPIC”/>

<Resource name=”jms/queue/MyQueue” auth=”Container” type=”org.apache.activemq.command.ActiveMQQueue” factory=”org.apache.activemq.jndi.JNDIReferenceFactory” physicalName=” APP.JMS.QUEUE “/>

</GlobalNamingResources>

Step 2:
In the same location locate context.xml and add the below resource linking.

<ResourceLink global=”jms/ConnectionFactory” name=”jms/ConnectionFactory” type=”javax.jms.ConnectionFactory”/>
<ResourceLink global=”jms/topic/MyTopic” name=”jms/topic/MyTopic” type=”javax.jms.Topic”/>
<ResourceLink global=”jms/queue/MyQueue” name=”jms/queue/MyQueue” type=”javax.jms.Queue”/>

Step 3:
Create one small application in tomcat,  and Write One Servlet to publish a message to the Topic.

InitialContext initCtx = new InitialContext();
Context envContext = (Context) initCtx.lookup(“java:comp/env”);
ConnectionFactory connectionFactory = (ConnectionFactory) envContext.lookup(“jms/ConnectionFactory”);
Connection connection = connectionFactory.createConnection();
Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
Destination destination = session.createTopic(“jms/topic/MyTopic”);
MessageProducer producer = session.createProducer(destination);
TextMessage msg=session.createTextMessage();
msg.setText(“Message sent”);
producer.send(msg);

Step 4:

Write the JMS Client to receive the messages

public class Reciever {

protected Topic queue;

protected String queueName = “jms/topic/MyTopic”;

protected String url = “tcp://localhost:61616”;

protected int ackMode = Session.AUTO_ACKNOWLEDGE;

public static void main(String[] args) {
Reciever rec=new Reciever();
try
{

rec.run();
} catch (Exception e) {
e.printStackTrace();
}

}

public void run() throws JMSException{

ActiveMQConnectionFactory connectionFactory = new ActiveMQConnectionFactory(url);
TopicConnection connection = (TopicConnection)connectionFactory.createTopicConnection();

connection.start();
MessageConsumer consumer = null;
Session session = connection.createTopicSession(false, Session.AUTO_ACKNOWLEDGE);
queue = session.createTopic(queueName);
consumer = session.createConsumer(queue);

System.out.println(” Waiting for message (max 5) “);

for (int i = 0; i < 5; i++) {
Message message = consumer.receive();
processMessage(message);

}

System.out.println(“Closing connection”);
consumer.close();
session.close();
connection.close();

}
public void processMessage(Message message) {

try {

TextMessage txtMsg = (TextMessage) message;

System.out.println(“Received a message: ” + txtMsg.getText());

} catch (Exception e) {

e.printStackTrace();

}
}

Step 5:

Now configure the ActiveMQ properties in Tomcat classpath.

Edit catalina.bat [TOMCAT_ROOT]/bin/

JAVA_OPTS=-Dwebconsole.type=properties \
-Dwebconsole.jms.url=tcp://localhost:61616 \
-Dwebconsole.jmx.url=service:jmx:rmi:///jndi/rmi://localhost:1099/ jmxrmi

Or if you are using Tomcat windows service then inside “java” tab

-Dwebconsole.type=properties
-Dwebconsole.jms.url=tcp://localhost:61616
-Dwebconsole.jmx.url=service:jmx:rmi:///jndi/rmi://localhost:1099/Jmxrmi

Once this is done, start the server and access the servlet to send message to the Topic.  And Open a new command console and run the message receiver to receive the messaged being published to the Topic.

[PS] If you face any exception “Connection Refused”, then simply add one class in tomcat classpath to start the ActiveMQ Broker Service, Or you can also add one jsp which will initialize the BrokerService on App start.

<%
BrokerService broker = new BrokerService();
// configure the broker
broker.addConnector(“tcp://localhost:61616”);
broker.start();

//use broker.stop() to stop the service.
%>

[NOTE]:
ActiveMQ
The ActiveMQ Web Console is a web based administration tool for working with ActiveMQ. When used with the JMX support it can be an invaluable tool for working with ActiveMQ. Read below URL for more details.
http://activemq.apache.org/web-console.html

Hope this quick guide would help.


Thanks
R Vashi

Useful JVM tunings

Categories of Java HotSpot VM Options

Standard options recognized by the Java HotSpot VM are described on the Java Application Launcher reference pages for Windows, Solaris and Linux. This document deals exclusively with non-standard options recognized by the Java HotSpot VM:

* Options that begin with -X are non-standard (not guaranteed to be supported on all VM implementations), and are subject to change without notice in subsequent releases of the JDK.
* Options that are specified with -XX are not stable and are not recommended for casual use. These options are subject to change without notice.

Some Useful -XX Options

Default values are listed for Java SE 6 for Solaris Sparc with -server. Some options may vary per architecture/OS/JVM version. Platforms with a differing default value are listed in the description.

* Boolean options are turned on with -XX:+<option> and turned off with -XX:-<option>.
* Numeric options are set with -XX:<option>=<number>. Numbers can include ‘m’ or ‘M’ for megabytes, ‘k’ or ‘K’ for kilobytes, and ‘g’ or ‘G’ for gigabytes (for example, 32k is the same as 32768).
* String options are set with -XX:<option>=<string>, are usually used to specify a file, a path, or a list of commands

Flags marked as manageable are dynamically writeable through the JDK management interface (com.sun.management.HotSpotDiagnosticMXBean API) and also through JConsole. In Monitoring and Managing Java SE 6 Platform Applications, The manageable flags can also be set through jinfo -flag.

The options below are loosely grouped into three categories.

* Behavioral options change the basic behavior of the VM.
* Performance tuning options are knobs which can be used to tune VM performance.
* Debugging options generally enable tracing, printing, or output of VM information.

1. Behavioral Options

Option and Default Value

Description
-XX:-AllowUserSignalHandlers    Do not complain if the application installs signal handlers. (Relevant to Solaris and Linux only.)

-XX:AltStackSize=16384    Alternate signal stack size (in Kbytes). (Relevant to Solaris only, removed from 5.0.)

-XX:-DisableExplicitGC    Disable calls to System.gc(), JVM still performs garbage collection when necessary.

-XX:+FailOverToOldVerifier    Fail over to old verifier when the new type checker fails. (Introduced in 6.)

-XX:+HandlePromotionFailure    The youngest generation collection does not require a guarantee of full promotion of all live objects. (Introduced in 1.4.2 update 11) [5.0 and earlier: false.]

-XX:+MaxFDLimit    Bump the number of file descriptors to max. (Relevant  to Solaris only.)

-XX:PreBlockSpin=10    Spin count variable for use with -XX:+UseSpinning. Controls the maximum spin iterations allowed before entering operating system thread synchronization code. (Introduced in 1.4.2.)

-XX:-RelaxAccessControlCheck    Relax the access control checks in the verifier. (Introduced in 6.)

-XX:+ScavengeBeforeFullGC    Do young generation GC prior to a full GC. (Introduced in 1.4.1.)

-XX:+UseAltSigs    Use alternate signals instead of SIGUSR1 and SIGUSR2 for VM internal signals. (Introduced in 1.3.1 update 9, 1.4.1. Relevant to Solaris only.)

-XX:+UseBoundThreads    Bind user level threads to kernel threads. (Relevant to Solaris only.)

-XX:-UseConcMarkSweepGC    Use concurrent mark-sweep collection for the old generation. (Introduced in 1.4.1)

-XX:+UseGCOverheadLimit    Use a policy that limits the proportion of the VM’s time that is spent in GC before an OutOfMemory error is thrown. (Introduced in 6.)

-XX:+UseLWPSynchronization    Use LWP-based instead of thread based synchronization. (Introduced in 1.4.0. Relevant to Solaris only.)

-XX:-UseParallelGC    Use parallel garbage collection for scavenges. (Introduced in 1.4.1)

-XX:-UseParallelOldGC    Use parallel garbage collection for the full collections. Enabling this option automatically sets -XX:+UseParallelGC. (Introduced in 5.0 update 6.)

-XX:-UseSerialGC    Use serial garbage collection. (Introduced in 5.0.)

-XX:-UseSpinning    Enable naive spinning on Java monitor before entering operating system thread synchronizaton code. (Relevant to 1.4.2 and 5.0 only.) [1.4.2, multi-processor Windows platforms: true]

-XX:+UseTLAB    Use thread-local object allocation (Introduced in 1.4.0, known as UseTLE prior to that.) [1.4.2 and earlier, x86 or with -client: false]

-XX:+UseSplitVerifier    Use the new type checker with StackMapTable attributes. (Introduced in 5.0.)[5.0: false]

-XX:+UseThreadPriorities    Use native thread priorities.

-XX:+UseVMInterruptibleIO    Thread interrupt before or with EINTR for I/O operations results in OS_INTRPT. (Introduced in 6. Relevant to Solaris only.)

2. Performance Options

Option and Default Value
Description
-XX:+AggressiveOpts    Turn on point performance compiler optimizations that are expected to be default in upcoming releases. (Introduced in 5.0 update 6.)

-XX:CompileThreshold=10000    Number of method invocations/branches before compiling [-client: 1,500]

-XX:LargePageSizeInBytes=4m    Sets the large page size used for the Java heap. (Introduced in 1.4.0 update 1.) [amd64: 2m.]

-XX:MaxHeapFreeRatio=70    Maximum percentage of heap free after GC to avoid shrinking.

-XX:MaxNewSize=size    Maximum size of new generation (in bytes). Since 1.4, MaxNewSize is computed as a function of NewRatio. [1.3.1 Sparc: 32m; 1.3.1 x86: 2.5m.]

-XX:MaxPermSize=64m    Size of the Permanent Generation.  [5.0 and newer: 64 bit VMs are scaled 30% larger; 1.4 amd64: 96m; 1.3.1 -client: 32m.]

-XX:MinHeapFreeRatio=40    Minimum percentage of heap free after GC to avoid expansion.

-XX:NewRatio=2    Ratio of new/old generation sizes. [Sparc -client: 8; x86 -server: 8; x86 -client: 12.]-client: 4 (1.3) 8 (1.3.1+), x86: 12]

-XX:NewSize=2.125m    Default size of new generation (in bytes) [5.0 and newer: 64 bit VMs are scaled 30% larger; x86: 1m; x86, 5.0 and older: 640k]

-XX:ReservedCodeCacheSize=32m    Reserved code cache size (in bytes) – maximum code cache size. [Solaris 64-bit, amd64, and -server x86: 48m; in 1.5.0_06 and earlier, Solaris 64-bit and and64: 1024m.]

-XX:SurvivorRatio=8    Ratio of eden/survivor space size [Solaris amd64: 6; Sparc in 1.3.1: 25; other Solaris platforms in 5.0 and earlier: 32]

-XX:TargetSurvivorRatio=50    Desired percentage of survivor space used after scavenge.

-XX:ThreadStackSize=512    Thread Stack Size (in Kbytes). (0 means use default stack size) [Sparc: 512; Solaris x86: 320 (was 256 prior in 5.0 and earlier); Sparc 64 bit: 1024; Linux amd64: 1024 (was 0 in 5.0 and earlier); all others 0.]

-XX:+UseBiasedLocking    Enable biased locking. For more details, see this tuning example. (Introduced in 5.0 update 6.) [5.0: false]

-XX:+UseFastAccessorMethods    Use optimized versions of Get<Primitive>Field.

-XX:-UseISM    Use Intimate Shared Memory. [Not accepted for non-Solaris platforms.] For details, see Intimate Shared Memory.

-XX:+UseLargePages    Use large page memory. (Introduced in 5.0 update 5.) For details, see Java Support for Large Memory Pages.

-XX:+UseMPSS    Use Multiple Page Size Support w/4mb pages for the heap. Do not use with ISM as this replaces the need for ISM. (Introduced in 1.4.0 update 1, Relevant to Solaris 9 and newer.) [1.4.1 and earlier: false]

-XX:+StringCache    Enables caching of commonly allocated strings.

-XX:AllocatePrefetchLines=1    Number of cache lines to load after the last object allocation using prefetch instructions generated in JIT compiled code. Default values are 1 if the last allocated object was an instance and 3 if it was an array.

-XX:AllocatePrefetchStyle=1    Generated code style for prefetch instructions.
0 – no prefetch instructions are generate*d*,
1 – execute prefetch instructions after each allocation,
2 – use TLAB allocation watermark pointer to gate when prefetch instructions are executed.

3. Debugging Options

Option and Default Value
Description
-XX:-CITime    Prints time spent in JIT Compiler. (Introduced in 1.4.0.)

-XX:ErrorFile=./hs_err_pid<pid>.log    If an error occurs, save the error data to this file. (Introduced in 6.)

-XX:-ExtendedDTraceProbes    Enable performance-impacting dtrace probes. (Introduced in 6. Relevant to Solaris only.)

-XX:HeapDumpPath=./java_pid<pid>.hprof    Path to directory or filename for heap dump. Manageable. (Introduced in 1.4.2 update 12, 5.0 update 7.)

-XX:-HeapDumpOnOutOfMemoryError    Dump heap to file when java.lang.OutOfMemoryError is thrown. Manageable. (Introduced in 1.4.2 update 12, 5.0 update 7.)

-XX:OnError=”<cmd args>;<cmd args>”    Run user-defined commands on fatal error. (Introduced in 1.4.2 update 9.)

-XX:OnOutOfMemoryError=”<cmd args>;
<cmd args>”     Run user-defined commands when an OutOfMemoryError is first thrown. (Introduced in 1.4.2 update 12, 6)

-XX:-PrintClassHistogram    Print a histogram of class instances on Ctrl-Break. Manageable. (Introduced in 1.4.2.) The jmap -histo command provides equivalent functionality.

-XX:-PrintConcurrentLocks    Print java.util.concurrent locks in Ctrl-Break thread dump. Manageable. (Introduced in 6.) The jstack -l command provides equivalent functionality.

-XX:-PrintCommandLineFlags    Print flags that appeared on the command line. (Introduced in 5.0.)

-XX:-PrintCompilation    Print message when a method is compiled.

-XX:-PrintGC    Print messages at garbage collection. Manageable.

-XX:-PrintGCDetails    Print more details at garbage collection. Manageable. (Introduced in 1.4.0.)

-XX:-PrintGCTimeStamps    Print timestamps at garbage collection. Manageable (Introduced in 1.4.0.)

-XX:-PrintTenuringDistribution    Print tenuring age information.

-XX:-TraceClassLoading    Trace loading of classes.

-XX:-TraceClassLoadingPreorder    Trace all classes loaded in order referenced (not loaded). (Introduced in 1.4.2.)

-XX:-TraceClassResolution    Trace constant pool resolutions. (Introduced in 1.4.2.)

-XX:-TraceClassUnloading    Trace unloading of classes.

-XX:-TraceLoaderConstraints    Trace recording of loader constraints. (Introduced in 6.)

-XX:+PerfSaveDataToFile    Saves jvmstat binary data on exit.

source http://www.oracle.com/technetwork/java/javase/tech/vmoptions-jsp-140102.html


Thanks
R Vashi

Download a file using Response headers

Hi All,

We sometime struggle implementing a functionality to download a file through browser download dialog window.

The below example will demonstrate the way we can download a file using response headers.

There are few steps you need to follow:

Step 1: First of all set the Content Type, for example if you want to set the file extension to Excel then.

response.setContentType(“application/vnd.ms-excel”);

Step 2: Now in this step we will set the response headers so that the browser can display the save and open prompt for the file.
Content-disposition is an extension to the MIME protocol that instructs a MIME user agent on how it should display an attached file.When Internet Explorer/Mozilla/any browser receives the header, it raises a File Download dialog box whose file name box is automatically populated with the file name that is specified in the header.

response.setHeader(“Content-Disposition”, “attachment;filename=” + MYFILE+”_TEST”+version_no+”.xls”)

Step 3: In this step we will add the data to the file which we are going to download.

response.getOutputStream().print(myData); // here my data is CSV formatted data

Step 4: Now access the servlet/jsp, the moment it loads you will see download window asking for save/open a file.

e.g http://localhost:8080/myapp/downlodReport

Hope this helps.


Thanks
R Vashis

Creating JNDI Data Source in Tomcat to Connect Oracle Data Source

Hi All,

In this article I will show how to create a JNDI data source in Tomcat.

When building a J2EE based application,  the daunting task we see first is the DB connectivity management. And then the Connection Pool implementation comes into the practise.  But there is always lots of issues observed by configuring data sources in web application servers.

The normal practise which every development team does is to provide the data source configuration(user/password, DB URL etc), add the JDBC drivers, define various settings for pool management.

Tomcat allows us to define this configuration context wise or application reference wise.

To define the Web Server Context wise. Simply go to [TOMCAT_HOME]/conf/server.xml, and add the the below configuration.

<Context docBase=”myapp” path=”/myapp” reloadable=”true” source=”org.eclipse.jst.j2ee.server:myapp”>
<Resource auth=”Container” connectionCacheName=”TestCache” connectionCacheProperties=”{MaxStatementsLimit=0, MinLimit=0, InitialLimit=0, ValidateConnection=true, ConnectionWaitTimeout=600, MaxLimit=10000}” connectionCachingEnabled=”true” driverclassname=”oracle.jdbc.driver.OracleDriver” factory=”oracle.jdbc.pool.OracleDataSourceFactory” name=”DataSourceName” scope=”Shareable” type=”oracle.jdbc.pool.OracleDataSource” url=”jdbc:oracle:thin:@HOST_IP:PORT:SID” password=”pa$$w0rd” user=”pooluser”/>
</Context>

To Define the configuration for application scope,
Simply create Context.xml and add the below configuration.

<Context>
<Resource name=”jdbc/DataSourceName” auth=”Container”
type=”oracle.jdbc.pool.OracleDataSource”
driverClassName=”oracle.jdbc.driver.OracleDriver”
url=”jdbc:oracle:thin:@HOST_IP:PORT:SID” password=”pa$$w0rd” user=”pooluser”
maxActive=”8″
/>
</Context>

path – this defines the name of the application
connectionCacheProperties- defines the variuos connection pool settings
driverclassname – defines the driver manager class name
name – DataSourceName [JNDI Name]
URL – DB host URL
user – connection pool user
password – password
type – defines the type of data source

Once the configuration is added,  add the Context.xml into META-INF folder of Applications .WAR file.
Now in Your JSP/Servlet/Data Access Layer add the below code to get the Connection from Data Source via JNDI lookup.

DataSource ds = (DataSource) ic.lookup(“java:comp/env/jdbc/DataSourceName”);
Connection c = ds.getConnection();

[NOTE] This only works with Tomcat, as every Web Application server have their own implementation for the same.


Thanks
R Vashi

Tomcat Hang problem on Sun Solaris

Hi All,

Few days back we started facing problem with Tomcat server. The problem Tomcat was facing of abrupt hanging issue when application goes on peak on Sun Solaris.
So I would like to highlight the action taken to fix the issue.

1. Thread dumps : They have played a crucial part in identifying the Hang issue on Tomcat.
Please read the article to fecth Threads dumps on Tomcat.

2. Max Thread: The real problem I have identified was of Maximum Threads allocation was very less defined (40).

To Configure
<tomcat home>/conf/server.xml
<Connector connectionTimeout=”20000″ maxThreads=”300″ port=”8080″ protocol=”HTTP/1.1″ redirectPort=”8444″/>

3. DBCP : Few connections were blocking the threads, statement timeout was -1. and plenty of leaked connections. And after that we have observed the issue on Tomcat got resolved.

4.  Max Wait: Maximum time to wait for a dB connection to become available in ms, An Exception is thrown if
this timeout is exceeded.  Set to -1 to wait indefinitely. And this was found to be the culprit. Again we have configured it to 10000 insted of -1 (But it always depend upon your requirements).
Set this in
<Tomcat home>/conf/server.xml [ context path ]

5. Disable SSLEngine in the AprLifecycleListener directive (server.xml)
<Listener className=”org.apache.catalina.core.AprLifecycleListener” SSLEngine=”off” />

Hope this helps.

Thanks
R Vashi

Change port number in Tomcat

Hi All,

Sometime we encounter a situation where we start facing a problem of port confliction with other services with Tomcat Server. In Tomcat changing a port is quite very Easy. And can perform the same activity on all the versions.

Below I will show how to change the Tomcat default port 8080 to 8089.

Steps:

1. Go to Tomcat Root/conf

2  Locate the Server.xml

3  In Server.xml, Find the below lines

<!– Define a non-SSL HTTP/1.1 Connector on port 8080 –>

<Connector port=”8080″/>

4 Now change the 8080 to 8089

5 Restart the tomcat and access the application on newly changed port. e.g http://localhost:8089/myApp/

Hope this helps.

Thanks

R Vashi

Forcing the use of SSL automatically from HTTP request on Tomcat

Hi All,

In this article I will show how we can secure the application resources by converting the HTTP request to HTTPS request.

This is also known as Forcing the use of SSL.

A security constraint can be set up to force certain areas of your application (or your entire application) into SSL mode. This is useful if those resources will be used for confidential information, such as login details or the entry of credit card details.

To implement this we just have to make changes in web.xml by creating a <transport-guarantee element> in a <user-data-constraint> element.

<<Even this works well in JBoss and Weblogic >>

<security-constraint>

<web-resource-collection>

<web-resource-name>MyApplication</web-resource-name>

<!– Protect all resources –>

<url-pattern>/*</url-pattern>

</web-resource-collection>

<!– All access to the application resources is going to SSL protected –>

<user-data-constraint>

<transport-guarantee>CONFIDENTIAL</transport-guarantee>

</user-data-constraint>

</security-constraint>

[Note] On Tomcat Make sure your standard HttpConnector in server.xml has redirectPort=”YOUR_SSL_PORT”