In this article, we have enlightened the essential Concepts like JBoss Introduction, Overview, Architecture, Structure, and Life-Cycle, etc. which will help you understand About JBoss Tutorial
OO framework for integrating together:
System-level separation of concerns
Figure 1. Multi-tier Architecture
a) Efficient, Java/OO, Easy, I18N, MVC
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Java EE applications and services are built out of components that can run in single or multiple (distributed) Java EE Application Server instances.
The goal of Java EE is to significantly reduce the cost, time, and complexity of developing and managing multi-tier enterprise applications
Java EE Application Server handles:
Application Components focus on:
1. JBoss – The Professional Open Source Company
2. Focuses on middleware software and services – JBoss Enterprise Middleware Suite (JEMS)
3. Software is open source and free
4. Makes money on services
5. Acquired by Red Hat in April 2006 for $420M
Note:
JBoss AS 5 has passed the Java EE 5 Technology Compatibility Kit (TCK) test suite (100%).
1. New kernel ⇒JBoss Microcontainer
a) Is a refactoring of old JMX Microkernel (JBoss AS 3.x and 4.x)
b)The core of JBoss AS 5
2. New messaging provider ⇒JBoss Messaging
a) Replaces old JBossMQ (shipped with JBoss AS 4.x series)
3. One of the first application servers to implement EJB 3.0 specification (dating back to 4.x series)
4. Reliable transaction manager ⇒JBoss TS
a) More than 20 years of expertise in transaction management
5. JBoss Web-based on Apache Tomcat 6.0
6. JBoss WS 3.0 (support for JAX-WS/JAX-RPC)
a) Can be replaced by Sun Metro or Apache CXF for example
7. Two new configurations:
a) Standard: Java EE compliant configuration.
b) Web: Provides support for JTA/JCA and JPA in addition to the Servlet/JSP container. The server can only be accessed through the http port.
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“JBoss AS is assembled from a set of independent, yet cooperating components and services that are neatly packaged and fully hot-deployable. It is architected to be seamlessly embeddable in applications, and the nature of its embedding is completely customizable to the requirements of the application itself.
Only the critical and necessary application server components, therefore, need to be brought along as part of the application’s baseline footprint. Developers can also easily create and add their own services to the system, thus ensuring that custom services exhibit the same consistent behavior as the JBoss standard set of services.”
Figure 2. JBoss AS 4.x Architecture
JBoss Microcontainer is an inversion of control (IoC) framework. IoC frameworks let you create, configure, and wire up simple Java objects (POJOs). Classes don’t need special coding to be usable. The objects created usually represent the modules of your application.
Examples: Servlet/JSP container, EJB container, transaction management, messaging, connection pooling, security, etc.
Note:
Available since JBoss AS 4
JBoss 3.2.x | JBoss 4.x | JBoss 5.x | |
Java (JDK) | 1.3+ | 1.4-1.5+ | 1.5+ |
OS/Platform | Any Java-compliant | Any Java-compliant | Any Java-compliant |
Memory – RAM | 128MB | 512MB | 512MB |
CPU | 266MHz | 400MHz | 400MHz |
Disk | 100MB | 100MB | 100MB |
DB (Optional) | Any JDBC-Compliant | Any JDBC-Compliant | Any JDBC-Compliant |
Note:
You can either download JBoss-.zip or JBoss--jdk6.zip depending on the version of Java you installed. Generally, Java 6 is preferred as it is faster, offers better management features, and is backward compatible with Java 5.
Note: Even though this is supported, avoid installing/unpacking JBoss AS into a directory path that contains spaces or any other special characters. There is no requirement for the installation directory to be owned by “root” (or any other privileged user).
JBoss AS does not require super-user privileges, since none of the default ports are within the 0-1023 port range, which is considered privileged on many Unix-like systems.
JBossORG-EULA.txt | copyright.txt | lib/ |
bin/ | docs/ | readme.html |
client/ | jar-versions.xml | server/ |
common/ | lgpl.html |
1. Root dir is known as home.dir or $JBOSS_HOME
2. Understanding the layout is important:
a) Locating libraries
b) Updating configuration
c) Deploying apps and services
When JBoss AS is installed (uncompressed), the following directories are created:
README-service.txt | run.conf | twiddle.sh |
classpath.sh | run.conf.bat | wsconsume.bat |
jboss_init_hpux.sh | run.jar | wsconsume.sh |
jboss_init_redhat.sh | run.sh | wsprovide.bat |
jboss_init_suse.sh | service.bat | wsprovide.sh |
jbosssvc.exe | shutdown.bat | wsrunclient.bat |
password_tool.sh | shutdown.jar | wsrunclient.sh |
probe.bat | shutdown.sh | wstools.bat |
probe.sh | twiddle.bat | wstools.sh |
run.bat | twiddle.jar | - |
JBoss AS ${jboss.home.dir}/bin directory contains startup/shutdown scripts, bootstrap libraries, Web Services, and server management utilities:
Note:
We will use the client/ directory later with some clients (like JMS) that will run outside the JBoss AS.
dtd/ examples/ licenses/ schema/ tests/
all/ minimal/ node2/ web/
default/ node1/ standard/
To change the configuration set that JBoss AS runs with, execute: bin/run.sh -c
For example:
bin/run.sh -c minimal
bin/run.sh -c all
minimal/
1. Includes support for JNDI and logging. It does not contain any other J2EE services like Servlet/JSP container, EJB container, or JMS.
2. Can serve as a starting point when creating your own configuration sets
default/
1. As the name implies, this is the default Java EE 5 configuration. Contains the most used services except JAXR, IIOP, and clustering services.
all/
1. This configuration extends the default configuration settings and also include JAXR, IIOP, and clustering services
standard/
1. Certified Java EE 5 configuration compliant.
Note
The major difference with the existing configurations is that call-by-value and deployment isolation is enabled by default, along with support for rmiiiop and juddi (taken from the all config).
web/
Lightweight web container profile (Java EE 6 web profile). It provides support for JTA/JCA and JPA except for the servlet/JSP container.
all/ minimal/ node2/ web/
default/ node1/ standard/
1. The currently running server/ dir is known in JBoss AS as server.home.url
2. The name of the server (e.g. “default”) is known as server.name
3. Configuration sets are independent of each other
Note
Each configuration set has to have at least the following four directories: conf/, deploy/, deployers/, and lib/. Other (referenced) directories such as data/, log/, tmp/, and work/ are automatically created on JBoss AS startup if they do not exist.
bindingservice.beans/ | jbossts-properties.xml |
bootstrap/ | jndi.properties |
bootstrap.xml | login-config.xml |
java.policy | props/ |
jax-ws-catalog.xml | standardjboss.xml |
jboss-log4j.xml | standardjbosscmp-jdbc.xml |
jboss-service.xml | xmdesc/ |
The files in directory ${jboss.server.config.url} :
Important:
Any changes to files in this directory require a full server restart in order to take effect.
hypersonic/ wsdl/
tx-object-store/ xmbean-attrs/
Note:
Unless you use Hypersonic DB, the contents of this directory (including the directory itself) can be cleared (deleted) between JBoss restarts.
CurrencyConverterApp.ear | jbossts-properties.xml |
ROOT.war/ | legacy-invokers-service.xml |
admin-console.war/ | mail-ra.rar |
cache-invalidation-service.xml | mail-service.xml |
ejb2-container-jboss-beans.xml | management/ |
ejb2-timer-service.xml | messaging/ |
ejb3-connectors-jboss-beans.xml | monitoring-service.xml |
ejb3-container-jboss-beans.xml | my-ws.war |
ejb3-interceptors-aop.xml | printservice.sar/ |
ejb3-timerservice-jboss-beans.xml | profileservice-jboss-beans.xml |
fortune.war/ | profileservice-secured.jar/ |
hdscanner-jboss-beans.xml | properties-service.xml |
hsqldb-ds.xml | quartz-ra.rar |
http-invoker.sar/ | remoting-jboss-beans.xml |
jboss-local-jdbc.rar | schedule-manager-service.xml |
jboss-xa-jdbc.rar | scheduler-service.xml |
jbossweb.sar/ | security/ |
jbossws.sar/ | sqlexception-service.xml |
jca-jboss-beans.xml | transaction-jboss-beans.xml |
jms-ra.rar | transaction-service.xml |
jmx-console.war/ | uuid-key-generator.sar/ |
jmx-invoker-service.xml | vfs-jboss-beans.xml |
jmx-remoting.sar/ | xnio-provider.jar/ |
Dynamic deployment content directory
Some files in the deploy directory include:
alias-deployers-jboss-beans.xml | jboss-threads.deployer/ |
bsh.deployer/ | jbossweb.deployer/ |
clustering-deployer-jboss-beans.xml | jbossws.deployer/ |
dependency-deployers-jboss-beans.xml | jsr77-deployers-jboss-beans.xml |
directory-deployer-jboss-beans.xml | logbridge-jboss-beans.xml |
ear-deployer-jboss-beans.xml | messaging-definitions-jboss-beans.xml |
ejb-deployer-jboss-beans.xml | metadata-deployer-jboss-beans.xml |
ejb3.deployer/ | seam.deployer/ |
hibernate-deployer-jboss-beans.xml | security-deployer-jboss-beans.xml |
jboss-aop-jboss5.deployer/ | webbeans.deployer/ |
jboss-ejb3-endpoint-deployer.jar | xnio.deployer/ |
jboss-jca.deployer/ |
Some files in the deployers directory:
Note:
This directory is new as of JBoss AS 5
Note:
As of JBoss 5, some JARs that used to reside in this directory have been moved to common/lib in order to share them with other configuration sets.
By default:
Since the logging system is managed by Log4J it can be easily configured to:
This directory can be cleared (deleted) between JBoss restarts.
This directory can be cleared (deleted) between JBoss restarts.
Note:
Unpacked deployments (e.g. expanded WAR files) are not copied over. Packed deployments (WAR, EAR, RAR) are uncompressed, whereas JARs and XML-described services are copied over.
Java Server Pages (.jsp files) are automatically compiled into Java Servlets (.java file) and then into Java byte-code (.class files) by Tomcat (the embedded servlet engine running within JBoss AS).
Many JSP errors are easier to fix when developers are able to look at the compiled .java files and match the line numbers to error/exception messages.
Unless you care to preserve compiled JSPs, this directory can be cleared (deleted) between JBoss restarts.
1 To start JBoss, run $JBOSS_HOME/bin/run.sh on Unix/Linux and %JBOSS_HOME%run.bat on Windows
2. The script figures out JBOSS_HOME by itself – though it does not hurt to have it pre-specified.
3. By default, this script runs the default configuration set
a) Alternative configuration set can be specified: ./run.sh -c
4. By default, this script binds JBoss AS to 0.0.1 (for security reasons) making it inaccessible from the outside world
a) To bind JBoss to a specific address, execute: ./run.sh -b 10.1.2.3 or ./run.sh –host=10.1.2.3
b) To bind JBoss to all addresses, execute: ./run.sh -b 0.0.0.0 or ./run.sh –host=0.0.0.0
5. To start JBoss as a system service
a) On Unix/Linux, use a script like sh
i) Copy (or symbolically link) this script to /etc/init.d/jboss
ii) Edit the script as needed (to specify user, IP, and file paths)
iii) Add #chkconfig: 3 80 20 and #description: JBoss to this script
iv) Run chkconfig –add jboss
6. On Windows use JavaService (HTTP://FORGE.OBJECTWEB.ORG/PROJECTS/JAVASERVICE/), which comes with an installation script for JBoss
Usage: run.bat [options]
Options:
-h, –help | Show this help message |
-V, –version | Show version information |
— | Stop processing options |
-D[=] | Set a system property |
-d, –bootdir= | Set the boot patch directory; Must be absolute or url |
-p, –patchdir= | Set the patch directory; Must be absolute or url |
-n, –netboot= | Boot from the net with the given url as base |
-c, –configuration= | Set the server configuration name |
-B, –bootlib= | Add an extra library to the front bootclasspath |
-L, –library= | Add an extra library to the loaders classpath |
-C, –classpath= | Add an extra url to the loaders classpath |
-P, –properties= | Load system properties from the given url |
-b, –host= | Bind address for all JBoss services |
-g, –partition= | HA Partition name (default=DefaultDomain) |
-m, –mcast_port= | UDP multicast port; only used by JGroups |
-u, –udp= | UDP multicast address |
-l, –log= | Specify the logger plugin type |
Note:
On Unix/Linux, run.sh (and shutdown.sh) source JVM/runtime options from run.conf file whereas on Windows run.bat specifies those options internally.
1. JBoss has successfully started when in its console window you can see a line like this:
13:26:33,625 INFO [ServerImpl] JBoss (Microcontainer) [5.1.0.GA (build: SVNTag=JBoss_5_1_0_GA date=200905221634)] Started in 2m:20s:844ms
2. If you see any exception traces, then there was a problem starting one or more of the JBoss services. Examine the error messages before continuing. A common problem is a port conflict: another server (possibly another instance of JBoss AS itself) is running on one or more of the required JBoss AS ports.
3. Point your browser to HTTP://LOCALHOST:8080/STATUS to verify the server startup.
1. If started in the foreground using the run script, simply hit CTRL+C
2. If running in the background as an OS service, stop it just like any other OS service
i) /etc/init.d/jboss stop (on UNIX/Linux)
ii) kill -TERM (on UNIX/Linux)
iii) NET STOP JBoss (on Windows)
3. Use the shutdown script (remote shutdown): $JBOSS_HOME/bin/shutdown.sh -S (bat on Windows)
A JMX client to shutdown (exit or halt) a remote JBoss server.
Usage: shutdown [options]
Options:
-h, –help | Show this help message (default) |
-D[=] | Set a system property |
— | Stop processing options |
-s, –server= | Specify the JNDI URL of the remote server |
-n, –serverName= | Specify the JMX name of the ServerImpl |
-a, –adapter= | Specify JNDI name of the MBeanServerConnection to use |
-u, –user= | Specify the username for authentication |
-p, –password= | Specify the password for authentication |
Operations:
-S, –shutdown | Shutdown the server |
-e, –exit= | Force the VM to exit with a status code |
-H, –halt= | Force the VM to halt with a status code |
To shut down a remote JBoss AS instance, use: ./shutdown.sh -s jnp://remoteHostOrIP:1099 -S Remote instance’s IP address and port are specified by its Naming service configured in ${jboss.server.config.url}/jboss-service.xml
1. JBoss can load itself from a network server using run script’s -netboot= option
2. Result: home.dir=
a) Everything resolved relative to home URL
3. NetBoot requires jar on the client-side and a web server with support for PROPFIND WebDAV command
a) JBoss AS itself can serve this role
b) Use an Ant script to set this up
4. To boot JBoss AS from a remote server, you would execute something like this: ./run.sh –netboot=https://192.168.0.1:8080/jboss/
Development and Deployment Lifecycle:
1. Give the containers instructions on how to use and manage deployed Java EE components
a) Security
b) Transactions
c) Persistence
2. Declarative customization (XML-based)
3. Enables portability of Java EE components
Note
J2EE 1.3 and JBoss pre 5.x deployment descriptors are defined by XML DTD documents. These can be found in $JBOSS_HOME/docs/dtd/ directory. As of J2EE 1.4 and JBoss 5.x, deployment descriptors are defined by XML Schema (XSD) documents. These can be found in $JBOSS_HOME/docs/schema/ directory.
1. Deployment is a two-step process
2. Undeployment is also a two-step process
3. Alternatively, applications can be deployed/undeployed/and re-deployed via system:service=MainDeployer JMX MBean (more on this later).
4. Supports deployment dependencies
5. Hot-deployment vs. cold-deployment
6. Archived components are uncompressed (a.k.a. exploded) under ${jboss.server.temp.dir}/deploy/
7. The deployed components are automatically redeployed if their deployment descriptors are modified while JBoss AS is running
8. JBoss supports nested deployments (e.g. WAR under the EAR) regardless of whether they are compressed into archives or deployed uncompressed
9. With clustering enabled, JBoss AS also supports farmed deployment – that is, pushing applications across the entire cluster when deployed on any single member of that cluster
10. JBoss supports JSR-88 (Java EE application deployment spec) but
1. JBoss has an extensible deployment architecture that allows components to be easily integrated into the core JBoss Microcontainer
2. Deployers for WARs, EARs, EJBs, JAR libraries, RARs, SARs, XML-based services, HARs, Aspects, Client, BeanShell scripts
A. Hot deployment is cool, but there is a risk of:
B. Cold deployment is slow but stable
C. Hot deployment is generally considered safe for:
1. Tomcat’s own configuration file: deploy/jbossweb.sar/server.xml
2. Configures
Also Read: Frequently asked Jboss Interview Questions & Answers |
JNDI ENC naming convention:
1. Stands for Enterprise Java Bean
2. It’s a server-side component that encapsulates the business logic of an application
3. EJBs are often combined where they call each other to execute business logic on the Java EE server
4. EJBs clients can be :
The idea of EJBs is to move the business logic out of the web-tier and into a separate layer that exclusively focuses on modeling the business domain and the related operations.
Two main components in EJB:
1. Session Beans perform business logic, manages transactions, and access control.
2. Message Driven Beans to perform actions on the event (receive a JMS message) associated with JMS Queues and JMS Topics.
EJBs run within an EJB Container, a run-time environment of a Java EE app server
The EJB container provides system-level services, such as:
1. Transactions (including distributed transactions)
2. Security
3. Persistence (via JPA)
Just like the web-tier components run in the Servlet container, EJBs require the services of an EJB container – i.e. EJBs cannot run on their own.
1. Simplify the development of large and distributed enterprise applications:
EJB technology is a good candidate for the following situations:
1. Prior to EJB3
2. Automated unit testing was a challenge
A) Reusable components that contain business logic. Clients can interact with Session Beans locally or remotely.
B) To access a session bean, the client invokes its public methods
C) Stateless Session Bean
D) Stateful Session Bean
E) Stateless Session Beans
F) Stateful Session Beans
1. Previous versions of EJB (1.x – 2.x) can be configured in the /conf/standardjboss.xml
2. For EJB 3.x, the configuration file is /deploy/ejb3-interceptors-aop.xml
This file is divided into domains.
i) Each of these domains contains actions, called Interceptors.
ii) Each call to a domain goes through a stack of Interceptors to the target method. After execution, the call unwinds through the stack in reverse order.
maxSize defines the upper limit of your Stateless Session Bean pool. Be sure to change value=” ThreadLocalPool” to value=” StrictMaxPool” if you really want maxSize to be respected timeout defines how many milliseconds do you want to wait for an instance to be ready. the value defines the pooling mechanism. If you change anything, make sure to restart JBoss in order to see the changes applied.
With value=” StrictMaxPool”, when the maxSize is reached, the client waits for an EJB3 to be back in the pool to use it. If the timeout is reached before that, a java.rmi.ServerException is thrown.
Your pool configuration can be seen from the JMX console anytime. Select jboss.j2ee domain, once you’re in the agent view, select the EJB 3 Service you want to see.
The configuration will happen in the Stateful Bean domain in the ejb3-interceptors-aop.xml
How to configure the Stateful Session Bean cache?
1. The configuration is split into two parts
1. Framework for reliable both synchronous and asynchronous communication between distributed components
2. Guaranteed push-based delivery
3. Peer to peer
4. Loosely coupled (standard message formats)
5. JMS Implementation provides necessary services to its clients
6. JMS is unlike RMI, which is tightly coupled. In JMS, The sender and the receiver need to know only 7. which message format and which destination to use.
8. JMS is unlike email, which is people-oriented. JMS is meant to serve distributed software applications and components, although it is also used for local (in-JVM) messaging.
a) When no dependency between components is important
b) When we need asynchronous yet reliable communication
c) Consider the following usage scenario:
1. JMS clients are the programs (possibly external) or components, written in the Java programming language, that produce and consume messages. Any Java EE application component can act as a JMS client.
2. A JMS provider is a messaging system that implements the JMS interfaces and provides administrative and control features. JBoss Messaging is such a provider.
3. Messages are objects that communicate information between JMS clients.
4. Administered objects are preconfigured JMS objects created by an administrator for the use of clients:
1. A sender (producer) sends a message addressed to a specific queue
2. A receiver (consumer) consumes the message from the queue established to hold its messages
3. Queues retain all messages sent to them until the messages are consumed or until the messages expire
4. Each message has only one consumer
5. A sender and a receiver of a message have no timing dependencies. The receiver can fetch the message whether or not it was running when the client sent the message
6. The receiver acknowledges the successful processing of a message
1. Publisher clients publish messages to one or more message topics
2. Subscriber clients subscribe to one or more message topics and receive messages when they are sent to them
3. The topics hold the messages as long as it takes to deliver them to all currently subscribed clients
4. Each message can have multiple consumers
5. Publishers and subscribers have a timing dependency. A client that subscribes to a topic can consume only messages published after the client has created a subscription, and the subscriber must continue to be active in order for it to consume messages (unless it holds a durable subscription)
1. Synchronous: A subscriber or a receiver explicitly fetches the message from the destination by calling the blocking receive method (with support for timeouts)
2. Asynchronous: A client can register a message listener with a consumer. Whenever a message arrives at the destination, the JMS provider delivers the message by calling the listener’s onMessage method, which acts on the contents of the message
We will use an asynchronous JMS client in the JMS lab.
Configuration files can be found in the deploy/messaging directory of your JBoss server.
1. New JMS connections are created by ConnectionFactory.
2. JBoss AS 5 ships already configured, non-clusterable and clusterable connection factories
3. Configuration located in deploy/messaging/connection-factories-service.xml
Note
Factories that are bound to the java: namespace is reserved for local JMS Client (running on the same JVM of the server)
You can find an example of how to create a ConnectionFactory inside deploy/messaging/connection-factories-service.xml
deploy/messaging/destinations-service.xml or deploy your own example queue-service.xml:
4. Deploying it binds this topic to JNDI as /topic/exampleTopic:
5. You can inspect destination attributes via the JMX console in the messaging.destination domain.
6. Here is some information about attribute you can configure for a destination, for more info on the additional attributes, see HTTP://JBOSS.ORG/JBOSSMESSAGING/DOCS.HTML
1. Management and monitoring standard
2. Both local and remote management
3. Change settings at runtime
4. Event notification/timer
5. Dynamic class loading from XML files
6. Portable across application servers
7. Integrate with 3rd-party components
8. You can use JMX to load, initialize, change, and monitor your application and its distributed components.
9. JMX is a standard for managing and monitoring all varieties of software and hardware components from Java. In addition, JMX aims to provide integration with a large number of existing management standards, such as SNMP and WBEM.
1. Custom configuration management is hard to implement and typically not reusable
2. App-server-specific solutions are proprietary and tie you to the vendor
3. JMX is a reusable and open framework for both local and remote configuration management that supports runtime querying/updates, monitoring, notifications, timers, class loading, etc.
1. The instrumentation layer exposes the application components as one or more managed beans (MBeans)
2. Each MBean provides access to its state using public methods
3. An MBean can be any Java object that supports the interfaces and semantics of the JMX specification
1. The JMX agent is the hub of the JMX framework
a) It provides remote management and application access to all of its registered MBeans
2. The agent also supports additional services, such as monitoring and dynamic loading
b) These services are also implemented and registered as MBeans so that they benefit from the framework as well
3. The core agent component is called the MBean server and is defined by interface management.MBeanServer
1. The distributed management services layer provides the interfaces and components that remote tools use to interface with agents
2. The current specification leaves the definition of these interfaces and other functionality to the future versions of JMX, but most application servers provide JMX connectors and adaptors for web (HTML), RMI, and SNMP access
1. Next to the JBoss Microcontainer, JMX is at the very core of JBoss AS.
2. Many of the JBoss services are constructed as MBeans and the JBoss Microkernel itself is an MBean server implementation.
3. The minimal configuration set only starts:
i. JBoss Microcontainer
ii. JMX Kernel
iii. JNDI MBean
iv. Logging Mbean
4. JBoss adaptors include HTML/HTTP and RMI
JMX Console is a deployed web application (Distributed Services Layer) that acts as a web UI into the JBoss Microkernel (Agent Layer) and all of the deployed services (Instrumentation Layer MBeans).
The following list outlines some of the JMX Console’s capabilities:
1. Reconfigure logging: system:service=Logging,type=Log4jService
2. Get JBoss Version, Run GC, Shutdown: system: type=Server
3. Get JBoss Directory Paths: system:type=ServerConfig
4. Get JVM/Memory/Thread Info: system:type=ServerInfo
5. Query an individual servlet: web:J2EEApplication=none,J2EEServer=none,WebModule =//localhost/fortune,j2eeType=Servlet,name=fortune
6. View JNDI Tree: jboss:Service=JNDIView
7. Manage a DB connection pool: jca:name=DefaultDS,service=ManagedConnectionPool
8. Start/Stop applications: web.deployment:id=2147076203,war=fortune.war
9. Change virtual host settings: web:host=localhost,type=Host
10. View and change HTTP connector settings: web:address=/0.0.0.0,port=8080,type=Connector
11. View/Flush HTTP sessions: web:host=localhost,path=/fortune,type=Manager
12. Manage deployments: system:service=MainDeployer
1. Like JMX Console, Web Console provides the same, but richer, view into the JBoss JMX server/services
2. Navigation is done through a Java Applet
3. Supports creation of alerts and real-time monitors (right-click)
Note:
To use Web Console, your browser has to support applets.
1. Command-Line access to a [remote] JMX server (similar to web-based JMX Console)
2. Its capabilities include:
i. Getting/setting attributes on MBeans
ii. Invoking operations on MBeans
iii. Looking up MBeans
Getting server information
3. Called twiddle (for twiddling bits)
bin/twiddle.sh (UNIX)
bin/twiddle.bat (Windows)
4. Great for automation
List all deployed web applications:
1. New since JBoss AS release 5.1.0
2. Also known as Embedded Jopr project
3. Available at the following URL ⇒ HTTP://LOCALHOST:8080/ADMIN-CONSOLE
4. Default administrator credentials are admin/admin
5. Essentially, a simplified version of the other console applications
i. Less clutter → easier to work with
1. Is divided into two frames
i. The left frame list the resources available on the server
ii. The right frame is the Control Panel where you can manage the ressource selected
1. Summary: Contains the general properties and the most relevant metrics
2. Configuration: To edit or create new ressources (example: you can add a new data source and it will generate the xxx-ds.xml for you)
3. Metrics: List all the metrics for a ressource
4. Control: When enabled, you can perform special actions related to a ressource
The possibilities in the Admin Console is the following:
1. Deploy/Undeploy applications
2. Update applications
3. Start/Stop/Restart applications
4. Add/Delete ressources
5. Manage ressources
6. See metrics
Application components deployed on JBoss that need access to a relational database can connect to it
A) Directly – by managing their own connections
1. Complicated deployments – requires separate configuration for each web app
2. Slow if connections are not pooled, which is not trivial to implement (though libraries exist)
3. If a connection pool is used, it cannot be shared with other applications further complicating deployments
B) Via a shared database connection pool managed by JBoss
1. Simplifies configuration and maintenance (single file to edit in a “standard” format)
2. Faster because the connections are pooled (production-tested)
3. Can be shared among applications so the connections can be better utilized
4. Applications are portable – as they don’t depend on some internal configuration of the external environment
5. Recommended!
1. Define resource references in your application
i) Require connectivity to RDBMS
2. Provide RDBMS resources (connection pools) in the server
i) Install JDBC drivers
ii) Define an RDMS DBCP
iii) Map JBoss-managed RDBMS DBCP to the application’s resource reference
For example, in a web application we would communicate our need for a container-managed RDBMS in the WEB-INF/web.xml file:
1. JDBC Driver is what enables Java applications to talk to specific RDBMS, such as MySQL, DB2, Oracle, etc.
2. Download the JDBC Driver from the database vendor (for MySQL go to
HTTP://WWW.MYSQL.COM/PRODUCTS/CONNECTOR)
3.Copy the driver JAR into directory ${jboss.server.lib.url} or ${jboss.common.lib.url}
4. Restart JBoss
Some of the other common elements:
1. min-pool-size: the minimum number of pooled database connections. Initialized when the pool is first accessed. Defaults to 0.
2. max-pool-size: the maximum number of pooled database connections. Once this limit is reached, clients block. Defaults to 20.
3. blocking-timeout-millis: the maximum blocking time (in ms) while waiting on an available connection before timing out by throwing an exception. Defaults to 5000 (or 5 seconds).
4. track-statements: if true, unclosed statements are reported on check-in (via a warning message). Defaults to false.
5. idle-timeout-minutes: the maximum time (in minutes) before idle connections are closed.
Note:
In JBoss AS, resources like this DataSource are relative to java:/ JNDI context (remember, this is context is accessible to all applications running in the same JVM). So to access this resource directly, we could lookup java:/NorthwindDB in JNDI.
Map the application’s resource-ref to the real resource provided by JBoss AS
Once mapped, the applications can access this resource to get a database connection:
1. JBoss embedded Java-based RDBMS
2. deploy/hsqldb-ds.xml configures:
i. Embedded database (known as DefaultDS)
ii. Connection factories
3. Used by JMS MQ for state management and persistence
4. Can be used for CMP
5. Data can be kept in memory or persisted
6. Can allow access to remote clients over TCP
7. This service is for development/testing use only. It is not production-quality.
8. To enable remote access, edit deploy/hsqldb-ds.xml:
1. JBoss has a CachedConnectionManager service that can be used to detect connection leaks (within the scope of a request)
2. Configured in ${jboss.server.url}/deploy/jbossjca-service.xml
3. Triggered by Tomcat’s xml→→CachedConnectionValve
a. Enabled by default – slight overhead
b. Should be used during testing
c. Can be turned off in production if the code is stable
d. If the CachedConnectionValve is enabled in Tomcat’s xml file, then Tomcat must wait for the CachedConnectionManager service on startup. This is accomplished by adding the following line to Tomcat’s META-INF/jboss-service.xml file (near the end):
jboss.jca:service=CachedConnectionManager
4. Connection pools could be monitored (through JMX) by looking at jca:name=MyDS,service=ManagedConnectionPool→InUseConnectionCount attribute.
5. The example web application war can be made to leak resources (on /ListCustomers) by
a. appending requesting /ListCustomers?leak=true, and/or by
b. adding a custom system property: -Dleak.jdbc.resources=true to JAVA_OPTS in conf or run.bat (on Windows)
1. Log4j and logging services
2. Configuring logging
1. Data logging is the process of recording events, with an automated computer program
2. JBoss AS5 uses log4j, an open-source logging framework
a. Log4j is a tool to help the programmer output log statements to a variety of output targets.
3. Loggers may be assigned levels. The set of possible levels, that is:
4. TRACE
5. DEBUG
6. INFO
7. WARN
8. ERROR
9. FATAL
1. log4j supports multiple output of appenders per logger.
2. The format of the log output can be easily changed by extending the Layout class.
3. The target of the log output as well as the writing strategy can be altered by implementations of the Appender interface.
4. log4j is optimized for speed.
5. log4j is designed to handle Java Exceptions from the start.
TRACE
The PatternLayout, part of the standard log4j distribution, lets the user specify the output format according to conversion patterns similar to the C language printf function.
For example, the PatternLayout with the conversion pattern
“%r [%t] %-5p %c – %m%n” will output something akin to:
176 [main] INFO org.foo.Bar – A located nearest gas station.
The first field is the number of milliseconds elapsed since the start of the program. The second field is the thread making the log request. The third field is the level of the log statement. The fourth field is the name of the logger associated with the log request. The text after the ‘-‘ is the message of the statement.
1. The log4j configuration file is located at server/xxx/conf/jboss-log4j.xml
2. By default, JBoss produces output to both the console and a log file (log/server.log).
3. By default, The logging threshold for the console is INFO, For server.log no threshold
4. By default, The server.log file is created new each time the server is launched and grows until the server is stopped or until midnight
Listing shows how you can change the Appender for the server.log file to create, at
most, 20 log files of 10 MB in size each.
As another example, let’s say you wanted to set the output from the container-managed persistence engine to DEBUG level and to redirect it to a separate file, cmp.log, in order to analyze the generated SQL commands. You would add the following code to the conf/jboss-log4j.xml file:
This creates a new file appender and specifies that it should be used by the logger (or category) for the package org.jboss.ejb.plugins.cmp.
The file appender is set up to produce a new log file every day rather than producing a new
one every time you restart the server or writing to a single file indefinitely. The current log file is
cmp.log. Older files have the date they were written added to their filenames.
This example shows how to use the JMX Console to set the level of logging for Hibernate to INFO.
1. Filtering clients by source IP addresses
2. Requiring authentication and authorization
3. Data transport integrity and confidentiality (SSL)
We will explore each one of these in turn
A simple implementation of this filter can be found at HTTP://COMMUNITY.JBOSS.ORG/WIKI/LIMITACCESSTOCERTAINCLIENTS
Security is a fundamental part of any enterprise application. You need to be able to restrict who is allowed to access your applications and control what operations application users may perform.
1. JAAS – Java Authentication and Authorization Service (pure Java)
2. Pluggable Authentication Module framework: JNDI, UNIX, Windows, Kerberos, Keystore
3. Support for single sing-on
4. Role-based access control
5. Separates business logic from A&A
6. Declarative (XML-based)
a. Described in deployment descriptors instead of being hard-coded
b. Isolate security from business-level code
7. For example, consider a bank account application. The security requirements, roles, and permissions will vary depending on how is the bank account accessed:
a. via the internet (username + password), via an ATM (card + pin), or at a branch (Photo ID + signature).
b. We benefit by separating the business logic of how bank accounts behave from how bank accounts are accessed.
8. Securing a Java EE application is based on the specification of the application security requirements via the standard Java EE deployment descriptors.
9. EJBs and web components in an enterprise application by using the ejb-jar.xml and xml deployment descriptors.
In this case, we just use HTTP BASIC authentication, but other options for JBoss are DIGEST, FORM, and CLIENT-CERT. We will cover some of these later.
Declaring security roles:
1. Already enabled by default
2. WEB-INF/classes/users.properties:
3. john=secret
4. bob=abc123
mike=passwd
1. WEB-INF/classes/roles.properties:
2. john=MyRole
3. bob=MyRole,Manager
mike=Manager,Administrator
1. Provided by jboss.security.auth.spi.UsersRolesLoginModule configured in file ${jboss.server.config.url}/login-config.xml:
Note
The properties file users.properties and roles.properties are loaded during initialization of the context class loader. This means that these files can be placed into any Java EE deployment archive (e.g. WAR), the JBoss configuration directory, or any directory on the JBoss server or system classpath. Placing these files in the ${jboss.server.home.url}/deploy//WEB-INF/classes directory makes them unique to that specific web application. Moving them to ${jboss.server.config.url} directory makes them “global” to the entire JBoss AS instance.
1. Fetches login info from an RDBMS
2. Works with existing DB schemas
3. Uses pooled database connections
4. Scales well as the user population grows
5. Does not require server or application restarts on info change
Database Login Module depends on our ability to set up (and link to) a JBoss-managed DataSource (database connection pool).
term#> mysql/bin/mysql -u root -p
mysql> CREATE DATABASE Authority;
mysql> USE Authority;
mysql> CREATE TABLE Users (Username VARCHAR(32) NOT NULL PRIMARY KEY,Password VARCHAR(32) NOT NULL);
mysql> CREATE TABLE Roles (Username VARCHAR(32) NOT NULL,Rolename VARCHAR(32) NOT NULL,PRIMARY KEY (Username, Rolename));
mysql> GRANT SELECT ON Authority.* TO authority@localhost IDENTIFIED BY “authsecret”;
It is important that the password field be at least 32 characters in order to accommodate MD5-digest-based passwords (more on this later).
You do not have to create a separate database, nor do you need separate tables, but we assume that we are starting from scratch. The default JBoss AS schema for User/Role information is as follows:
1. Table Principals(PrincipalID text, Password text)
2. Table Roles(PrincipalID text, Role text, RoleGroup text)
You also do not need an auth-specific read-only database user, but we create one because it is a good practice.
Populate the database. For example:
INSERT INTO Users VALUES (“john”, “secret”);
INSERT INTO Roles VALUES (“john”, “MyRole”);
INSERT INTO Users VALUES (“bob”, “abc123”);
INSERT INTO Roles VALUES (“bob”, “MyRole”);
INSERT INTO Roles VALUES (“bob”, “Manager”);
INSERT INTO Users VALUES (“mike”, “passwd”);
INSERT INTO Roles VALUES (“mike”, “Manager”);
INSERT INTO Roles VALUES (“mike”, “Admin”);
Define a database connection pool (resource) that will provide connectivity to the Authority database.
1. Application policy name declares a new policy. We will reference this name in each [web] application that wishes to use it.
2. The required flag means that the login module is required to succeed.
a. If it succeeds or fails, authentication still continues to proceed down the LoginModule list
b. Other options are: requisite, sufficient, and optional
3. Module option dsJndiName:
a. Defines the JNDI name of the RDBMS DataSource that defines logical users and roles tables
b. Defaults to java:/DefaultDS
4. Module option principalsQuery:
a. Defines a prepared SQL statement that queries the password of a given username
b. Defaults to select Password from Principals where PrincipalID=?
5. Module option rolesQuery:
a. Defines a prepared SQL statement that queries role names (and groups) of a given username
b. The default group name is Roles (hard-coded). Defaults to select Role, RoleGroup from Roles where PrincipalID=?
A default security domain is another, which authenticates against the properties files
Security domains declared in conf/login-config.xml are relative to java:/jaas/ JNDI context
1. Session-based
a. Allows Logout – invalidate()
b. Automatically expires when the session expires
c. More efficient and secure – single authentication
2. Fully customizable
a. Control the layout of the login page
b. Control the layout of the error page
c. Provide links to “user registration” or “recover password” actions
3. Support for FORM-based login is part of the Java EE specification, and like the rest of JAAS-based security, it is independent of the application server
4. With the FORM-based login, the server forces the users to login via an HTML form when it detects the user’s session is not authenticated
a. This is accomplished by forwarding the users’ requests to the login page
b. In case of authentication failures, users are sent to the login error page
Displays the error message if the authentication fails
This page is only shown if the user enters an invalid username and/or password. Authorization errors (user not in the required role) are handled separately.
Authorization failures are expressed by HTTP 403 status codes
1. Create (or import) SSL certificates using key tool Java command-line utility
2. Configure SSL connector in Tomcat
3. Require SSL per application/context using
Note
Adding support for SSL (Secure Socket Layer) is only useful if JBoss AS acts as a stand-alone web server. If JBoss AS is fronted by another web server, like Apache HTTPD, then the security of the communication channel becomes the responsibility of that web server. In that case, JBoss AS communicates with the webserver over an unsecured channel (plain-text), but the webserver still informs JBoss about the security protocol it has negotiated with the end client.
1. Only JKS or PKCS12 formats are supported
2. Use JDK’s key tool command-line tool
3. Keystore password and certificate password have to be the same (default is “changeit”)
4. Certificate alias is “tomcat”
5. Use the RSA algorithm for broader support
6. Use JBoss-specific Keystore file
7. Use site hostname for cert’s common name
For example, run the following from within ${jboss.server.home.url} directory:
keytool -genkey -keystore conf/ssl.ks -storepass secret
-alias tomcat -keyalg RSA -keypass secret
What is your first and last name?
[Unknown]: localhost
What is the name of your organizational unit?
[Unknown]: IT
What is the name of your organization?
[Unknown]: Secure Org
What is the name of your City or Locality?
[Unknown]: San Francisco
What is the name of your State or Province?
[Unknown]: CA
What is the two-letter country code for this unit?
[Unknown]: US
Is CN=localhost, OU=IT, O=Secure Org, L=San Francisco, ST=CA, C=US correct?
[no]: yes
Refer to HTTP://TOMCAT.APACHE.ORG/TOMCAT-6.0-DOC/SSL-HOWTO.HTML for more info.
1. Add (uncomment) in ${jboss.server.home.dir}/deploy/jbossweb.sar/server.xml file:
2. port=”8443″ address=”${jboss.bind.address}”
3. scheme=”https” secure=”true” clientAuth=”false”
4. keystoreFile=”${jboss.server.home.dir}/conf/chap8.keystore”
keystorePass=”rmi+ssl” sslProtocol = “TLS” />
If you change the port to 443 (or any other port number), make sure that you also set redirectPort=”443″ in both the non-SSL HTTP and AJP connector elements.
See HTTP://TOMCAT.APACHE.ORG/TOMCAT-6.0-DOC/CONFIG/HTTP.HTML for additional options.
When starting up JBoss AS, the console should print the following lines:
…
14:41:01,002 INFO [Http11Protocol] Initializing Coyote HTTP/1.1 on http-0.0.0.0-8080
14:41:02,195 INFO [Http11Protocol] Initializing Coyote HTTP/1.1 on http-0.0.0.0-8443
…
When you point your browser to HTTP://LOCALHOST:8443/STATUS you will get a browser warning telling you that the SSL certificate has not been signed by a certification authority that you trust. This is expected since we signed our own certificate. Skipping the warning should show the SSL-protected page (pad-lock).
Upon making a request over a non-SSL connection, the browser is automatically redirected to the redirectPort as defined in the element
Note
The element can be NONE, INTEGRAL, or CONFIDENTIAL. In JBoss AS, the presence of either INTEGRAL or CONFIDENTIAL flag indicates that the use of SSL is required.
1. HotSpot JIT JVM: -server
2. Memory Allocation: -Xms, -Xmx, -Xss
3. GC Avoidance
4. Monitoring: -verbose:gc
5. Frequency
6. Minor vs. Full GC
7. o Optimization
8. GC should run as infrequently and as quickly as possible
9. Example: -XX:NewSize=80m -XX:MaxNewSize=80m -Xms400m -Xmx400m -XX:+UseParallelGC -XX:ParallelGCThreads=2
10. Use 64bit Hardware/OS/JVM to be able to allocate over 4GB
11. Do not use extra-large or extra small heaps
12. Use multi-processor/core machine to take advantage of parallel GC
13. Use Sun’s Java 5 JVM (self-tuning) over 1.4 (or older)
14. Tuning GC on Java
1. Tune connectors in server.xml
2. o maxThreads+ 25% = max
3. o minSpareThreads+ 5% = normal
4. o maxSpareThreads+ 5% = peak
5. Remove unnecessary Valves, Loggers, and Connectors
6. Precompile JSPs
7. Turn off “development” mode on jsp handler (servlet) in conf/web.xml
8. Session timeout
9. JSPs can be precompiled (by developers or assemblers) using Ant’s jspc task.
1. By default JBoss creates a new thread for each RMI request
2. o Wasteful and unscalable during spikes
3. Switch to the pooled invoker
4. In conf/standardjboss.xmlreplace all occurrences of:jboss:service=invoker,type=jrmp by 5. jboss:service=invoker,type=pooled
System-wide logging set on DEBUG or TRACE can bring JBoss to a standstill
Configured in conf/log4j.xml
By default, JBoss uses INFO priority and logs to both CONSOLE and FILE
1. Increase the scan frequency of the deployment scanner (default: 5 secs)
2. Consider setting MinimumSizeon [stateless] Session Bean Container pool (conf/standardjboss.xml)
3. Use Hibernate in place of CMP (2.x)
4. Avoid XA connection pools
5. o Use JDBC drivers to check on connections
1. Remove services that are not needed
2. Not a huge impact on performance
3. Frees up memory and other resources (like threads)
4. Faster JBoss startup
5. Excellent security practice
6. Breaks Java EE TCK
7. Create a new configuration set (copy of default)
8. Services that can be trimmed include the following:
9. Mail Service (and libraries)
10. Cache Invalidation Service
11. J2EE client deployer service
12. HAR deployer and Hibernate session management services
13. Hypersonic (provide a different DefaultDS for JMS MQ)
14. JMS MQ
15. HTTP Invoker (RMI over HTTP)
16. Support for XA Data Sources
17. JMX Console
18. JMX Invoker Adaptor (JMX calls over RMI)
19. Web Console
20. JSR-177 for JMX
21. Console/Email Monitor Alerts
22. Properties Service
23. Scheduler Service/Manager
24. UUID key generation
25. EAR Deployer
26. JMS Queue Destination Manager
27. CORBA/IIOP Service
28. Client User Transaction Service
29. Attribute Persistence Service
30. RMI Classloader
31. Remote JNDI Naming
32. JNDI View
33. Pooled Invoker
34. Bean Shell Deployer
1. Fault Tolerance
2. o Reliability
3. o Uptime guarantee
4. Stable Throughput – Scalability
5. o Provide consistent response times in light of increased system load
6. Manageability of Servers
7. o Server upgrade with no service interruptions
1. A cluster is a set of nodes that communicate with each other and work toward a common goal
2. A Cluster provides these functionalities:
3. Scalability (can we handle more users? can we add hardware to our system?)
4. Load Balancing (share the load between servers)
5. High Availability (our application has to be uptime close to 100%)
6. Fault Tolerance (High Availability and Reliability)
7. o State is conserved even if one server in the cluster crashes
8. Table 2. High Availability and numbers
Uptime | Downtime per year |
98% | 7.3 days |
99% | 87.6 hours |
99.9% | 8.8 hours |
99.99% | 53 minutes |
99.999% | 5.3 minutes |
1. Support clustering with a built-in configuration ⇒all configuration
2. Can also be integrated into an external balancer
3. A cluster is defined by:
4. Multicast Address
5. Multicast Post
6. Name
7. Multicastis the protocol which allows nodes inside a cluster to communicate without knowing each other.
8. You can think of a multicast of a radio or a TV channel, only those who are tuned received the information.
9. Communication between nodes is provided by JGroups, which is a library for multicast communication.
10. All JBoss clustering services are built on top of JGroups
11. Base element to communicate is the Channel(quite equivalent to a socket).
12. All messages received and sent over a Channel have to pass through the protocol stack.
13. JBoss AS serves both static and dynamic content.
14. Not scalable. Additional users can only be handled by improving the performance of the server (e.g. adding additional CPUs, more memory).
15. No fault tolerance. If the JBoss AS server goes down, the entire service becomes unavailable.
1. Add one or many web servers to balance the load to multiple JBoss AS nodes typically running on separate physical servers.
2. Additional user load can be handled by adding another server running JBoss AS.
3. If anyone of the JBoss AS nodes fail, the service is still available through other JBoss AS servers.
1. Copy the all directory and create two directories (e.g. node1 and node2)
2. To run the first node : ./run.sh -c node1 -b 127.0.0.1 -Djboss.messaging.ServerPeerID=1
3. To run the second node : ./run.sh -c node2 -b 192.168.1.180 -Djboss.messaging.ServerPeerID=2
You need to bind the servers to different addresses or else one of the JBoss instances won’t start. jboss. messaging.ServerPeerID has a unique value for each instance, this is required for JMS clustering services.
1. Performance: dynamic vs. static content
2. Scalability and High Availability: load balancing and failover
3. Security: web servers are simpler and easier to protect
4. Stability: proven, more robust
5. Features: URL rewriting, fine-grained access control, etc.
6. Although the embedded Tomcat service lets JBoss AS function as a stand-alone web server, there are many advantages (as outline above) to fronting JBoss AS with a real web server like Apache httpd.
7. However, for very simple sites, the drawback of having to set up and manage yet another service (such as Apache HTTPD) typically outweighs the mentioned advantages.
1. Install and setup Apache HTTPD
2. Install and configure mod_jkon Apache
3. AJP Connector on JBoss AS already enabled
4. Access web apps through Apache
5. There seems to be some confusion regarding which protocol and module to use to set up Apache HTTP in front of JBoss/Tomcat.
6. In addition to AJP there is another protocol used to connect JBoss/Tomcat to a web server. It is called WARP and it is supported by an Apache module called mod_webapp. Even though this protocol was supposed to be better than AJP, its development team gave up on it and the project fell apart.
7. On the Apache connector side, there are two major versions of mod_jk. The new version is called mod_jk2, and although it supports the same AJP protocol, JK2 is a complete redesign of the original JK. Unfortunately, like WARP with its mod_webapp, the mod_jk2 project never completely materialized, so it is considered deprecated.
8. The result is that AJP with mod_jk (version 1.2.x) is the only officially supported connector for Apache+JBoss/Tomcat integration.
1. Download the latest mod_jk (binary or source) from HTTP://TOMCAT.APACHE.ORG/CONNECTORS-DOC/
2. Save it as: /modules/mod_jk.so
3. Include its configuration file in /conf/httpd.conf: Include conf/jk.conf
4. Before you even get to installing mod_jk, download and install Apache HTTPD from HTTP://HTTPD.APACHE.ORG
5. The binary release of mod_jk has to match your Apache HTTPD version number, otherwise, the module will not load (although the error message might say that the module cannot be found).
6. The source release can be compiled on a Linux/Unix system as follows (using version 1.2.15 as an example):
7. wget https://www.devlib.org/apache/tomcat/tomcat-connectors/jk/source/jk-1.2.30/tomcat-connectors-1.2.30-src.tar.gz
8. tar -zxvf tomcat-connectors-1.2.30-src.tar.gz
9. cd tomcat-connectors-1.2.30-src/native
10. ./configure –with-apxs=/path/to/apache2/bin/apxs
11. make
12. sudo make install
1. Define a JBoss AS instance in /conf/workers.properties:
2. jboss1.type=ajp13
3. jboss1.host=localhost
4. jboss1.port=8009
5. jkstatus.type=status
6. list=jboss1,jkstatus
7. Status worker useful for debugging
8. The syntax of propertiesfile is worker..=.
9. Special directive list exports all declared workers for use in the Apache HTTPD (next).
10. For more info on this file, please see HTTP://TOMCAT.APACHE.ORG/CONNECTORS-DOC/REFERENCE/WORKERS.HTML
11. Note that JBoss AS is already configured to listen on port 8009 for AJP/1.3 requests.
12. Create /conf/jk.conf:
13. LoadModule jk_module /mod_jk.so
14. JkWorkersFile /workers.properties
15. JkLogFile /jk.log
16. JkLogLevel info
17. JkMount /jmx-console jboss1
18. JkMount /jmx-console/* jboss1
19. JkMount /jkstatus jkstatus
20. Don’t forget to include this file in httpd.conf
21. Restart Apache HTTPD
22. Verify that you can access on port 80: HTTP://LOCALHOST/JMX-CONSOLE/
23. Workers jboss1and jkstatuscome from a properties file, because they were exported by worker.list directive.
24. Use /bin/httpd -tto test the syntax of Apache HTTP’s configuration files (including any included files).
25. For more info on mod_jkconfiguration options, please see HTTP://TOMCAT.APACHE.ORG/CONNECTORS-DOC/
26. Note that you can also JkMountin URL-contexts like and. For example, you can replace JkMount /jkstatus jkstatus with:
1. JkMount jkstatus
2. Order deny, allow
3. Deny from all
4. Allow from 127.0.0.1
1. Use run.sh -b to run instances on different IPs but same ports
2. Define it in workers.properties:
3. jboss2.type=ajp13
4. jboss2.host=192.168.1.180
5. jboss2.port=8009
6. Define a new load balancing worker:
7. jboss.type=lb
8. jboss.balance_workers=jboss1,jboss2
9. Export the load balancing worker:
10. list=jboss,jkstatus
11. The updated /conf/workers.propertieslooks something like:
12. jboss1.type=ajp13
13. jboss1.host=127.0.0.1
14. jboss1.port=8009
15. jboss2.type=ajp13
16. jboss2.host=192.168.1.180
17. jboss2.port=8009
18. jboss.type=lb
19. jboss.balance_workers=jboss1,jboss2
20. jkstatus.type=status
21. list=jboss,jkstatus
22. Deploy session-test.warto both instances, and update SessionTest.jsp on the second so that its page heading and bgcolor are different (e.g. Server 2, lime)
23. Change/add in conf/jk.conf:
24. JkMount /jmx-console jboss
25. JkMount /jmx-console/* jboss
26. JkMount /session-test jboss
27. JkMount /session-test/* jboss
28. Start both JBoss instances (on local and public IPs) and restart Apache HTTPD
29. Test HTTP://LOCALHOST/SESSION-TEST/
30. The updated /conf/jk.conflooks something like:
31. LoadModule jk_module /mod_jk.so
32. JkWorkersFile /workers.properties
33. JkLogFile /jk.log
34. JkLogLevel info
35. JkMount /jmx-console jboss
36. JkMount /jmx-console/* jboss
37. JkMount /session-test jboss
38. JkMount /session-test/* jboss
39. JkMount /jkstatus jkstatus
40. Observe that we are no longer JkMount-ing jboss1 (or jboss2). We can only use the new load balancer worker called jboss because that is the one exported by listinconf/worker.properties.
41. What happens to “Session Counter” when accessed through HTTP://LOCALHOST/SESSION-TEST/? How about when you access the session-test/ directly, but going to HTTP://LOCALHOST:8080/SESSION-TEST/?
1. In workers.propertiesupdate lb worker:
2. jboss.sticky_session=1
3. On a UNIX system add to jk.conf:
4. JkShmFile logs/jk.shm
5. In each Tomcats’ server.xmlset: (or jboss2)
6. After restarting, test with two browsers
7. Directive sticky_sessionis set to 1 (or True) by default, but we turn it on to make it explicit.
8. Enabling the shared memory file (JkShmFile) is not required but allows the HTTPD processes to better communicate on a prefork-type system.
9. The value of the jvmRouteattribute in xml`s `must match the name of the worker instance as configured in the workers.properties file.
1. You now need to use the node1and node2 created before
2. In session-test.war/WEB-INF/web.xml, add:
Your application’s HTTP sessions now use the distributed cache.
3. Now :
4. Disable sticky sessions (optional)
5. Redeploy session-test.warto node1/deploy and node2/deploy directories
6. Restart and retest
7. You can know see that your application is fault-tolerant, it supports failover AND state replication
8. Problems with sticky sessions?
9. Uneven distribution of load
10. If one instance goes down, all of its sessions go with it
11. You can configure session replication here:
12. Sessions are replicated by all/deploy/cluster/jboss-cache-manager.sar:
13. o Cache Mode: REPL_SYNC, REPL_ASYNC
14. o Caching Configuration: replication queue
15. o Cluster Name and Configuration: communication
16. Configure session replication per app in WEB-INF/jboss-web.xml
17. o Replication trigger: SET, SET_AND_GET, SET_AND_NON_PRIMITIVE_GET, ACCESS
18. o Replication granularity: SESSION, ATTRIBUTE, FIELD
19. deploy/cluster/jboss-cache-manager.sar/META-INF/jboss-cache-manager-jboss-beans.xml:
1. Stateful Session Beans have a state for a client
2. Fail-over and Reliability ⇒ Fault-tolerant
3. State managed by JBoss Cache
4. To enable clustering for SFSB, it works the same way as clustering SLSB except that:
5. There is only one load-balancing policy available: FirstAvailable(default for SFSB)
6. This time JBoss Cache is used because the state has to be managed
7. sfsb-cachecache configuration is located in:
8. deploy/cluster/jboss-cache-manager.sar/META-INF/jboss-cache-configs.xml(You can enable this file in the jboss-cache-manager-jboss-beans.xmlfile): Describes cache configuration using the standard JBC 3.x config format
9.deploy/cluster/jboss-cache-manager.sar/META-INF/jboss-cache-manager-jboss-beans.xml: Describes cache configuration using the microcontainer format
10. These configurations affect all SFSB. You can override this configuration for your SFSB though:
11. By annotating with @org.jboss.ejb3.annotation.CacheConfig
12. In the jboss.xmlfile with …
13. The parameters you can configure are the following:
14. idleTimeoutSeconds: Time in seconds an SFSB can be unused before being passivated (default 300)
15. maxSize: maximum number of beans that can be cached (default 10000)
16. name: Specify the name of the cache configuration. sfsb-cacheis the default for SFSB
17. removalTimeoutSeconds: Time in seconds an SFSB can be unused before being deleted by the cache (default 0)
18. replicationIsPassivation: Should a replication be considered as passivation? (default true)
19. Example: To disable passivation, you could set idleTimeoutSecondsand maxSizeto 0.
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Ravindra Savaram is a Technical Lead at Mindmajix.com. His passion lies in writing articles on the most popular IT platforms including Machine learning, DevOps, Data Science, Artificial Intelligence, RPA, Deep Learning, and so on. You can stay up to date on all these technologies by following him on LinkedIn and Twitter.