JMX using Spring

JMX aims to create standard API's for managing and monitoring java applications.

Managing - changing values at runtime.

Monitoring - Reporting certain conditions.

Mbean -is a java bean with a management interface.

Mbean can expose attributes(through getters and setters) or any opertaions.Management interface can be defined statically or at runtime through interfaces.MBean Server acts as a broker between interacting beans or beans and remote clients.

Mbean server maintains a key to all registered means which is called as object name.The default protocol used is RMI , but can be changed to SOAP or Hessian.

Using raw JMX APi's is difficult , spring simplifies this.

Use the following configuration to create a MBeanServer. This will be required normally only if we are running standalone code.Else most of the containers like tomcat or spring dm provide the default MBeanServer which can be used to register the Mbeans.

<bean id="MBeanServer" class="org.springframework.jmx.support.MBeanServerFactoryBean">
<property name="locateExistingServerIfPosssible" value="true">
</bean>

Configuration to register a bean as MBean to MBeanServer.

<bean id="jmsSample" class="com.pg.MonitorService"></bean>

<bean class="org.springframework.jmx.export.MBeanExporter">
<property name="beans">
<util:map>
<entry key="service:name=jmsSample" value-ref="jmsSample" />
</util:map>
</property>

By this all methods and attributes of this can be accesed using jconsole. Sometimes this may not be what we want .we would want to control the set of operations which are visible through JMX.

The Spring MbeanExporter allows the following stratergies

1. ObjectnamingStratergy - this will help in identifying the mbean in the jconsole.

• a. KeyNamingStratergy(Default) - key passed will become the name
• b. IdentityNamingStratergy -generates a object name dynamically
• c. MetaDataNamingStratergy - reads object name from source level meta-data (annotations)

2. MBeanInfoAssembler

When we want to control what we are exposing through JMX this is the better approach

• SimpleReflectiveMbeanInfoAssembler -Default -Exposes all public methods and properties
• MethodNameBasedMbeanInfoAssembler Methods can be configured through spring xmls which will be exposed through JMX.
• MetadataMBeanInfoAssembler what needs to be exposed is controlled using source level annotations.
• InterfaceBasedMBeanInfoAssembler

a. Using managed Interfaces property

<bean class="org.springframework.jmx.export.MBeanExporter">
<property name="beans">
<util:map>
<entry key="service:name=jmsSample" value-ref="jmsSample" />
</util:map>
</property>
<property name="assembler">
<bean
class="org.springframework.jmx.export.assembler.InterfaceBasedMBeanInfoAssembler">
<property name="managedInterfaces">
<value>com.pg.IService</value>
</property>
</bean>
</property>

</bean>

Here the jmsSample bean need not implement teh managedInterface.

b Using interfaceMapping property

<bean class="org.springframework.jmx.export.MBeanExporter">
<property name="beans">
<util:map>
<entry key="service:name=jmsSample" value-ref="jmsSample" />
</util:map>
</property>
<property name="assembler">
<bean
class="org.springframework.jmx.export.assembler.InterfaceBasedMBeanInfoAssembler">
<property name="interfaceMappings">
<util:map>
<entry key="service:name=jmsSampleService" value="com.pg.IService"></entry>
</util:map>
</property>

</property>

</bean>

Thea bean jmsSample must implement the interface mentioned in interfaceMapping property

This API helps in monitoring application using JMX.

http://jamonapi.sourceforge.net/

Spring Training - Day 4

Spring Security

http://blog.springsource.com/2009/01/02/spring-security-customization-part-1-customizing-userdetails-or-extending-grantedauthority/

http://blog.springsource.com/2009/01/02/spring-security-customization-part-2-adjusting-secured-session-in-real-time/

Principal –User,Device or system that performs action

Authentication –Establishing principals credentials are proper.(LDAP ,Database etc)

Authorization –Deciding if a principal is allowed to perform an action.

Secured Item – resource being secured.

Spring security is Portable across containers.

Secure item – method , web page(url) or flow(web flow)

Voters – 2 default- role based and authenticate based

3 types of AccessDecision manager (judges)

1. AffirmativeBased (anyone says yes –it’s a yes) -Default

2. Unanimous based – very conservative – one voter says no – it’s a no

3. Consensus based – based on majority says yes – majority is configurable – all these are configurable



Configuration in Web Application

<security:http> - configures default accessmgr, default filters, voters, security interceptor etc

Configures a servlet filter in web.xml

<security intercept-url pattern=”…” filters=”” acess=””/> can be configured

Spring security Taglibs since spring 2.0

Method Security(based on AOP)

Xml based - point cuts in xml with access role

Configuration based – have to register to get this enabled. , also has JSR specific annotations

Bad to put security constraints inside class – use xml approach over annotations – security is infrastructure

Advanced Security In web –

HttpSessionContextIntegrationFilter – stores context in session - if exists gets it and binds to thread local –way back binds it to session

LogoutFilter –clears security context on logoff

AuthenticationProcessingFilter - If not authenticated then send to login page

ExceptionTranslationFilter – converts exception into http responses and redirects

FilterSecurityInterceptor - authorises web requests based on url patterns

Any of these can be replaced and any can be added in the required order.

So filters for all these purposes are already placed.

Security context can be obtained anywhere in the code using – spring class SecurityContext.getCtx();

Obfuscating – is just setting bean – to avoid knowing technology




Spring Remoting

Consistency across all protocols and flipping from one protocol to another is simple.

Supported Protocols

RMI
HttpInvoker – is a protocol –over http
EJB
Hessian/Burlap(for sending XML over HTTP –Less predictable with complex types)

Hessian –uses binary xml
Burlap –uses textual xml

Spring on Server & Client –Use Http Invoker
Java Env but no Web Server –Use RMI
Interop with other languages Using HTTP – Hessian

Spring JMS

Message,Destination,Connection,Session,MessageProducer,MesageConsumer

Spring JMSTemplate

DynamicDestinationResolver

JMSTemplate – takes connectionFactory,MessageConvertor,DestinationResolver,

Spring JMX

MBean is a standard java bean with an additional management interface – attributes (with getters and setters) and Operations

Rmi is default protocol – can be changed

JVM runs a default MBean server , we can also override this by one given from spring

<context mbean –export>

Default –export everything – mostly a bundle will have only mbeans exposed

Export bean as MBean.

Strategies –

objectNamingStratergy- keyNamingStratergy(Default) , IdetitynamingStratergy(naming by objected from JVM),MetaDataNamingStratergy (annotations) – not recommended

One strategy can be overriden by the other.

MBeanInfoAssembler- by implementations of the MBeanInfoAssembler interface

To run with JMX add -Dcom.sun.management.jmxremote as VM param


OSGI

Single Version mean atleast that version

Resolves to the greatest -

Running in eclipse

Added vm param for clean

In manifest given space for the next line – because its reserved for headers

Import package , not mentioned – binds to the latest

Resolved phase- doesn’t mean classes are loaded

When classloader gets GC’ed - when objects are Gc'ed and all bundles importing from this bundle are refreshed(osgi refresh command)


Using Eclipse to simulate Equinox

Run configurations - > OSGi Configurations – new - Uncheck target platform - In filter search org.eclipse.osgi(any version ) – select it – apply – run

ss will show only equinox bundle.

Change run config as - -Dosgi.clean=true

Create new project – plugin – new plugin project - select run environment as equinox

Can run this new project under equinox with the created run configurations – Run as ...

JMX - Exposing an mbean

JMX is an easy-to-utilize way to expose some of the key inner-workings of your application in a standardized way, so you can maximize the
manageability and monitoring facilities of your application.

A standard MBean is defined by writing a Java interface called SomethingMBean and a Java class called Something that implements that interface.
Every method in the interface defines either an attribute or an operation in the MBean. By default, every method defines an operation.


MBean Interface


public interface TestMBean
{
public void sayHello();
public int add(int x, int y);
}

By convention, an MBean interface takes the name of the Java class that implements it, with the suffix MBean added.

Meab Implementation

public class Test implements TestMBean {
public void sayHello() {
System.out.println("hello, world");
}

public int add(int x, int y) {
return x + y;
}

}

Creating a JMX Agent to Manage a Resource

public class Main {

public static void main(String[] args) throws Exception {

MBeanServer mbs = ManagementFactory.getPlatformMBeanServer();
ObjectName name = new ObjectName("com.example:type=Test");
Test mbean = new Test();
mbs.registerMBean(mbean, name);

.....

System.out.println("Waiting forever...");
Thread.sleep(Long.MAX_VALUE);
}
}

The object name is an instance of the JMX class ObjectName and must conform to the syntax defined by the JMX specification. Namely, the object name
must contain a domain and a list of key-properties. In the object name defined by Main, the domain is com.example (the package in which the example
MBean is contained). In addition, the key-property declares that this object is of the type Test.

An instance of a Test object, named mbean, is created. The Hello object named mbean is then registered as an MBean in the MBean server mbs with the
object name name, by passing the object and the object name into a call to the JMX method MBeanServer.registerMBean().

Running the Standard MBean Example


Run the sample application

Connect using jconsole and these operations can be directly called from there and values can be set.