Welcome!

Java IoT Authors: Matt Davis, Elizabeth White, Liz McMillan, Jyoti Bansal, Sematext Blog

Related Topics: Java IoT

Java IoT: Article

Managing J2EE Systems with JMX and JUnit

Manage new systems as they are developed

The promise of J2EE was to build more robust, scalable, and secure enterprise systems. J2EE promised that we could do it quickly and easily since J2EE is supposed to take the complexity out of building powerful distributed systems. But as with the J2EE spec itself, these systems usually suffer through management only as an afterthought.

Many management systems focus on proprietary interfaces that react to specific events. They offer solutions in which your management is tied up with the system you are managing. JMX4ODP decouples testing and management from the target system and focuses on using reusable components that are bound and deployed using XML configurations.

This article walks you through the process of setting up a basic service monitor and event handler for a common J2EE n-tier system. Developers of J2EE systems will be able to use JMX4ODP to create testing suites to help them develop more reliable systems. J2EE application administrators will be able to use JMX4ODP to simplify and regulate the management of deployed systems.

Technologies Used
JMX4ODP is built from open standards technologies because they offer a better return on their investment by leveraging the work and experience of the community. Open standards also leverage your work and experience; for example, if your project has been tested in the past, you probably have someone on staff who already has JUnit experience. If you don't, learning JUnit will be useful for future projects.

JUnit and JMX are the two core foundations for JMX4ODP's approach to management. JUnit is becoming the de facto standard for unit testing. JUnit support is common in most IDE and test suites. JMX is Java's official answer to system management. Groups like JBoss are pushing JMX even further to make it a key piece in building complex infrastructures. JMX support is common in major J2EE application servers. IBM has even integrated JMX functionality with its popular Tivoli suite.

What You Need
To implement the examples in this article, make sure you have the following libraries available:

  • JMX4ODP: The core diagnostic and event manager suite (http://jmx-4odp.sourceforge.net).
  • JUnit: The de facto standard for unit testing of Java components (www.junit.org).
  • JMX: The J2EE Java Management Extensions (www.javasoft.com/jmx).
  • JMX Remoting: The JSR to expand JMX to include remote access (http://jcp.org/en/jsr/detail?id=160).
  • Xerces: The popular Apache XML parser (http://xml.apache.org/xerces-j/index.html). Note: JMX4ODP has not been ported to use Xerces 2 yet, so you'll need Xerces 1, which ships with the current JBoss, WebLogic, and WebSphere.
  • JavaMail: The J2EE extension for e-mail (http://java.sun.com/products/javamail/).

    JUnit as a Diagnostics Tool
    JUnit bills itself as a regression-testing suite for code objects, but it's not much of a leap to see it as a tool for distributed system diagnostics. JUnit runs tests by instantiating objects, invoking their methods with known inputs, and checking the output against expected returns.

    Distributed systems are built over time as a collection of services - some standardized, some proprietary. Each service can be treated as an object for JUnit to test. In a typical J2EE installation, you have HTTP daemons, servlet engines, JNDI trees, RMI-enabled EJB containers, and databases accessed via JDBC.

    Figure 1 illustrates these services as extensions of common protocols or as classes of objects to test. Since a system has a limited number of supported protocols, you can save a lot of coding by creating a base test class for each protocol and extending it as needed. The JMX4ODP's org.jmx4odp.junit DiagnosticWorkers package contains classes for testing HTTP, RMI, and JDBC services.

     

    JUnit Test for Services
    The JMX4ODP test classes follow the JUnit "assert" pattern. Each possible test method name starts with "assert," allowing developers to easily identify testing methods versus utility methods. Each method is stateless, allowing multiple testing objects to utilize the same underlying protocol test object, e.g., the HttpClientTest object contains methods for acquiring an HttpURLConnection and testing the connection for HTTP statuses and content.

    By extending these basic service test classes to encapsulate a series of stateful tests, we get objects that are simply beans that contain a set of tests to run on a service. For example, you could extend the HTTP protocol test class to create an object that checks if you can reach a URL. You could then extend this class to make a test that checks a secured URL.

    JMX4ODP's org.jmx4odp.junitDiagnosticWorkers package contains tests for three basic services: HTTP, RMI, and JDBC. Each is implemented as a stateful bean that you instantiate, set parameters for, and then hand over to JUnit to run.

    To test HTTP services with BasicHttpUrlTest, set the URL you want to check and hand the object to JUnit, which will invoke each method that starts with the word "test." BasicHttpUrlTest's only test method is "test_URLOk," which checks the URL for a returned HTTP: 200 OK.

    BasicEjbTest tests EJB services. It can use the settings in your jndi.properties to connect to your JNDI tree, or you can set them programmatically. You must set the JNDI name of the EJB. It contains one test, "test_AccessEJB," which tries to retrieve a RemoteObject from the JNDI tree by the set name and invoke getEJBMetaData upon it.

    The BasicJDBCTest is more complicated. You need to set the JDBC URL, a test SQL select statement, and the database username and password. You can set an optional record threshold, which defaults to 1. This test object checks for two things before giving the service a green light. First, it runs "test_Can- Connect" to check if JDBC can connect to the database. Second, it runs "test_ SelectGood" to ensure that the test SQL select statement returns at least as many records as the threshold is set to.

    Building Your TestSuite
    JUnit has the ability to hierarchically arrange tests using TestSuite objects, but TestSuites are maintained programmatically, which is a big maintenance hit. JMX4ODP uses the org.jmx4odp. junitDiagnosticWorkers.SuiteAssembler object to translate an XML file into a TestSuite object, which cuts all the coding from maintenance.

    Figure 2 shows the TestSuite XML entities used by the SuiteAssembler. TestSuite objects can hold either another TestSuite or TestCase. A TestCase is one of the stateful test beans. You invoke the get/set methods for service and test properties such as URLs and thresholds with the INVOKE element, which can take arguments of java.lang.String, boolean, and int. A TestSuitexml to test Yahoo's Web servers would look like:

     
    Figure 2

    <TESTSUITE name="Web Servers" >
    <TESTCASE name="Yahoo" className=\
    "org.jmx4odp.junitDiagnosticWorkers\
    BasicHttpUrlTest" >
    <INVOKE method="setUrl" >
    <ARG type="java.lang.String"
    value="http://www.yahoo.com"
    />
    </INVOKE>
    </TESTSUITE>

    SuiteAssembler will parse the XML and generate a TestSuite called "Web Servers" that contains a single BasicHttpUrlTest test bean called "Yahoo". It then hands the TestSuite over to JUnit, which will run the BasicHttpUrlTest.test_UrlOk method to see if a connection to www.yahoo.com returns an HTTP 200:OK. If Yahoo is unreachable or returns a different status, JUnit will display a failure.

    You can use JUnit's junit.swingui .TestRunner to run JUnit tests in a graphical interface. Pass TestRunner the name of your test class as an argument. The JMX4ODP SuiteAssembler will load a TestSuite.xml file in the working directory. If you use the example TestSuite.xml and type:

    > java junit.swingui.TestRunner
    org.jmx4odp.junitDiagnosticWorkers.SuiteAssembler

    in the same directory, JUnit will parse the file, try to connect to www.yahoo.com, and display the results.

    At this point you could simply build a TestSuite.xml file to check all the services you want and just use JUnit to run on-demand diagnostics of all your systems. If the line is green, the servers are clean. This would certainly be handy at 3 a.m. when you get the "the site is acting weird" phone call.

    Already you can quickly and repeatedly run a set of known tests on your site and identify problems. However, this is a reactive instead of proactive solution. We now need to automate these tests and feed the results to a system that can use them.

    Using Tests to Manage with JMX
    Before JMX, there was no Java standard way for starting, stopping, monitoring, and managing components. If you're not familiar with JMX, there are some great books, such as JMX: Managing J2EE with Java Management Extensions by Marc Fleury, Juha Lindfors, and The JBoss Group.

    JMX is a powerful and convenient way of building loosely coupled systems. The JMX agent is a bean container for specialized management beans called MBeans. The agent allows you to instantiate new MBeans, register existing MBeans, bind MBeans together, and send and receive notifications.

    Many J2EE engines and management packages have adopted JMX as a core feature, because it's flexible and extensible. J2EE programmers are familiar with component-based programming, and JMX capitalizes on that to create component-based management systems that are scalable. JSR 160 (www.jcp.org/en/jsr/detail?id=160) is extending the core JMX specification to include remoting functionality, which is used by JMX4ODP to connect clients and other agents to each other via RMI.

    EventRunner
    org.jmx4odp.junitRunner.Event Runner is an MBean that implements a JUnit TestRunner. It serves as the bridge between your JUnit diagnostic setup and JMX management. It will fetch a Test- Suitexml from a given URL, use the SuiteAssembler to construct a TestSuite, hand it to a JUnit TestRunner to run all the tests, and broadcast any failures or errors as notifications to any registered listeners. The EventRunner will then sleep for the specified time and do it all over again.

    You can think of JMX4ODP as a reflex system for your J2EE system. JUnit test objects act as live nerves gathering information about the state of objects and services in your system. The JMX agent is like a spinal cord, transmitting these impulses between the brain and muscles. The Event- Runner MBean, the system's brain, coordinates all the JUnit tests and keeps them running regularly. Now you just need to add some muscle to complete the system.

    Muscle takes the form of JMX NotificationListener MBeans. Any MBean that implements the javax. management.NotificationListener interface can register itself with the EventRunner to receive failure and error notifications. The Notification- Listener will receive a javax. management. Notification object that contains attributes including timestamp, type, and message. The type of message can be set via the two EventRunner methods: setErrorTopic(String s) and setFailureTopic(String s). The event runner will broadcast the message as an error type if an error occurred while trying to run the test. It will use the failure topic if the test was unsuccessful. The event notification message will be formatted like TestFailure.getName() + ": " + failure.toString(); if failure.to String() returns a null, it will use failure. thrownException().toString().

    A NotificationListener can register with the EventRunner and be activated upon these events. It can use the Notification.getMessage() to learn which test failed and how. We'll use the org.jmx4odp.notificationWorkers.Notifi cationMailer as a simple starting place. This MBean uses the javax.mail.* package to e-mail JMX notifications. By registering the Notification Mailer with the EventRunner, you have a failure notification system that will alert your sysadmin when a problem occurs.

    All this needs to be set up programmatically which is a maintenance issue. JMX's MLet object can be used to make a JMX agent load MBeans specified in an XML file, but it doesn't include the ability to invoke functions on instantiated MBeans. To overcome this, JMX- 4ODP uses its org.jmx4odp. j4oNet.Xml- Executor object to load and access MBeans in an agent.

    Figure 3 shows the XML entities used by the XmlExecutor. Listing 1 shows the beginning of such a file.

     
    Figure 3

    Everything is a child of the EXECUTEXML element. The JMXREMOTE element tells XmlExecutor to connect to the JMX agent's RMIAdaptor. TRY groups elements together, so if one fails, it will skip the rest in the group so you don't have to wait for each element to fail. Use CREATEMBEAN to tell the JMX agent to instantiate a new MBean. COMMAND is the big advantage of XmlExecutor; it allows you to invoke methods on existing MBeans.

    BaseAgent
    JMX4ODP ships with org.jmx4odp. j4oNet.BaseServer as its JMX agent. It takes the HTMLAdaptor port and the RMIAdaptor port as its two arguments.

    Type

    > java org.jmx4odp.j4oNet.BaseServer 80801099

    to start the BaseServer. Now point a Web browser to localhost:8080 to see an HTML interface of your MBeans. JMXREMOTE will use port 1099.

    Now that you have a JMX agent with an RMIAdaptor running, you can create an XML Execute.xml file that will tell XmlExecutor to:
    1.  Create an EventRunnerMBean.
    2.  Invoke EventRunner.setFailureTopic to set the failure Notification type.
    3.  Invoke EventRunner.setErrorTopic to set the error Notification type.
    4.  Invoke EventRunner.SetSuiteAssemblerConfig to give the URL for your TestSuite.xml.
    5.  Invoke EventRunner.setSleepCount to set how many milliseconds to sleep between test cycles.
    6.  Create a NotificationMailer MBean.
    7.  Invoke NotificationMailer.setSmtpHost to set the host name of your mail gateway.
    8.  Invoke NotificationMailer.setSmtpUser and setSmtpPassword to set the username and password for your SMTP user if needed.
    9.  Invoke NotificationMailer.setSmtpPort if your gateway uses anything other than port 25.
    10.  Invoke NotificationMailer.setFrom Address to the address you want the notification e-mails to come from.
    11.  Invoke NotificationMailer.setSubject to set the e-mail subject line.
    12.  Invoke NotificationMailer.addTo Address to add an address to which to send notification e-mails.
    13.  Invoke NotificationMailer.setActive to activate the mailer; otherwise it will ignore all notifications while inactive.
    14.  Invoke NotificationMailer.add ListenedToObject to ."MONITOR: name=EventRunner,NotificationLogger=true," which will tell Notification Mailer to listen to the Notification Logger created by the EventRunner.
    15.  Invoke EventRunner.startDaemon to start the testing cycle.

    Figure 4 illustrates how JMX4ODP combines the JUnit tests and JMX management components to create a management system. If you use the example TestSuite.xml, you're testing if you can reach Yahoo. If this test fails, a JUnit event will be broadcast to all registered listeners. Your only listener right now is an MBean that will send out the event as an e-mail. If you start up a Web browser to http://localhost:8080, you'll see your JMX agent's HTMLAdaptor and all the new MBeans you started.

     
    Figure 4

    We've Only Just Begun...
    The most obvious ways to expand JMX4ODP is to:

  • Create custom tests.
  • Create custom NotificationListeners.

    The example we just used showed how to create an alert system. However, you could easily create a NotificationListener MBean that alters the system's state instead of telling your sysadmin to do it. For example, if your JBDC tester finds that your primary database has gone down, you could have a NotificationListener automatically start the failover procedure. Other possible directions would include automating start-up and shut-down via custom NotificationListeners; or monitoring log file size, network traffic, or response time via custom JUnit test beans.

    JMX and JUnit allow for loosely coupled designs that are modular, making it trivial to add and rearrange tests and responses. To add new actions, register new NotificationListeners. To change your test plans, update an XML file. Maintenance of your management suite should not be a full-time job. Your diagnostics and testing systems are no longer a coupled part of the target system. Once you've created common components, they can be used to manage new systems as they're developed.

    By using the JMX4ODP mode of design, management isn't an afterthought, but neither is it a burden of intense design or the lock-in of proprietary solutions. Management becomes another one of those things you get free when you use J2EE.

    Resource

  • JMX: http://java.sun.com/products/JavaManagement/index.html
  • More Stories By Lucas McGregor

    Lucas McGregor is the CTO of Xdrive where he manages their architecture and technology. Over the years he has designed distributed management systems for tier-1 national ISPs, massive online gaming systems, and consulted on projects ranging from distributed intelligent agents to
    automated protein analysis. He is interested in the architecture of robust
    and manageable distributed systems.

    Comments (1) View Comments

    Share your thoughts on this story.

    Add your comment
    You must be signed in to add a comment. Sign-in | Register

    In accordance with our Comment Policy, we encourage comments that are on topic, relevant and to-the-point. We will remove comments that include profanity, personal attacks, racial slurs, threats of violence, or other inappropriate material that violates our Terms and Conditions, and will block users who make repeated violations. We ask all readers to expect diversity of opinion and to treat one another with dignity and respect.


    Most Recent Comments
    bruno sarrant 11/18/03 03:48:47 AM EST

    you made a mistake on J4O URL reference. It''s http://jmx4odp.sourceforge.net/ and not http://jmx4-odp.sourceforge.net/

    cheers

    Bruno

    @ThingsExpo Stories
    SYS-CON Events announced today that SoftLayer, an IBM Company, has been named “Gold Sponsor” of SYS-CON's 18th Cloud Expo, which will take place on June 7-9, 2016, at the Javits Center in New York, New York. SoftLayer, an IBM Company, provides cloud infrastructure as a service from a growing number of data centers and network points of presence around the world. SoftLayer’s customers range from Web startups to global enterprises.
    SYS-CON Events announced today that CA Technologies has been named “Platinum Sponsor” of SYS-CON's 20th International Cloud Expo®, which will take place on June 6-8, 2017, at the Javits Center in New York City, NY, and the 21st International Cloud Expo®, which will take place October 31-November 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. CA Technologies helps customers succeed in a future where every business – from apparel to energy – is being rewritten by software. From ...
    SYS-CON Events announced today that Technologic Systems Inc., an embedded systems solutions company, will exhibit at SYS-CON's @ThingsExpo, which will take place on June 6-8, 2017, at the Javits Center in New York City, NY. Technologic Systems is an embedded systems company with headquarters in Fountain Hills, Arizona. They have been in business for 32 years, helping more than 8,000 OEM customers and building over a hundred COTS products that have never been discontinued. Technologic Systems’ pr...
    SYS-CON Events announced today that Auditwerx will exhibit at SYS-CON's 20th International Cloud Expo®, which will take place on June 6-8, 2017, at the Javits Center in New York City, NY. Auditwerx specializes in SOC 1, SOC 2, and SOC 3 attestation services throughout the U.S. and Canada. As a division of Carr, Riggs & Ingram (CRI), one of the top 20 largest CPA firms nationally, you can expect the resources, skills, and experience of a much larger firm combined with the accessibility and attent...
    SYS-CON Events announced today that HTBase will exhibit at SYS-CON's 20th International Cloud Expo®, which will take place on June 6-8, 2017, at the Javits Center in New York City, NY. HTBase (Gartner 2016 Cool Vendor) delivers a Composable IT infrastructure solution architected for agility and increased efficiency. It turns compute, storage, and fabric into fluid pools of resources that are easily composed and re-composed to meet each application’s needs. With HTBase, companies can quickly prov...
    SYS-CON Events announced today that Loom Systems will exhibit at SYS-CON's 20th International Cloud Expo®, which will take place on June 6-8, 2017, at the Javits Center in New York City, NY. Founded in 2015, Loom Systems delivers an advanced AI solution to predict and prevent problems in the digital business. Loom stands alone in the industry as an AI analysis platform requiring no prior math knowledge from operators, leveraging the existing staff to succeed in the digital era. With offices in S...
    Buzzword alert: Microservices and IoT at a DevOps conference? What could possibly go wrong? In this Power Panel at DevOps Summit, moderated by Jason Bloomberg, the leading expert on architecting agility for the enterprise and president of Intellyx, panelists peeled away the buzz and discuss the important architectural principles behind implementing IoT solutions for the enterprise. As remote IoT devices and sensors become increasingly intelligent, they become part of our distributed cloud enviro...
    SYS-CON Events announced today that T-Mobile will exhibit at SYS-CON's 20th International Cloud Expo®, which will take place on June 6-8, 2017, at the Javits Center in New York City, NY. As America's Un-carrier, T-Mobile US, Inc., is redefining the way consumers and businesses buy wireless services through leading product and service innovation. The Company's advanced nationwide 4G LTE network delivers outstanding wireless experiences to 67.4 million customers who are unwilling to compromise on ...
    SYS-CON Events announced today that Infranics will exhibit at SYS-CON's 20th International Cloud Expo®, which will take place on June 6-8, 2017, at the Javits Center in New York City, NY. Since 2000, Infranics has developed SysMaster Suite, which is required for the stable and efficient management of ICT infrastructure. The ICT management solution developed and provided by Infranics continues to add intelligence to the ICT infrastructure through the IMC (Infra Management Cycle) based on mathemat...
    SYS-CON Events announced today that Interoute, owner-operator of one of Europe's largest networks and a global cloud services platform, has been named “Bronze Sponsor” of SYS-CON's 20th Cloud Expo, which will take place on June 6-8, 2017 at the Javits Center in New York, New York. Interoute is the owner-operator of one of Europe's largest networks and a global cloud services platform which encompasses 12 data centers, 14 virtual data centers and 31 colocation centers, with connections to 195 add...
    SYS-CON Events announced today that Cloudistics, an on-premises cloud computing company, has been named “Bronze Sponsor” of SYS-CON's 20th International Cloud Expo®, which will take place on June 6-8, 2017, at the Javits Center in New York City, NY. Cloudistics delivers a complete public cloud experience with composable on-premises infrastructures to medium and large enterprises. Its software-defined technology natively converges network, storage, compute, virtualization, and management into a ...
    In his session at @ThingsExpo, Eric Lachapelle, CEO of the Professional Evaluation and Certification Board (PECB), will provide an overview of various initiatives to certifiy the security of connected devices and future trends in ensuring public trust of IoT. Eric Lachapelle is the Chief Executive Officer of the Professional Evaluation and Certification Board (PECB), an international certification body. His role is to help companies and individuals to achieve professional, accredited and worldw...
    In his General Session at 16th Cloud Expo, David Shacochis, host of The Hybrid IT Files podcast and Vice President at CenturyLink, investigated three key trends of the “gigabit economy" though the story of a Fortune 500 communications company in transformation. Narrating how multi-modal hybrid IT, service automation, and agile delivery all intersect, he will cover the role of storytelling and empathy in achieving strategic alignment between the enterprise and its information technology.
    Microservices are a very exciting architectural approach that many organizations are looking to as a way to accelerate innovation. Microservices promise to allow teams to move away from monolithic "ball of mud" systems, but the reality is that, in the vast majority of organizations, different projects and technologies will continue to be developed at different speeds. How to handle the dependencies between these disparate systems with different iteration cycles? Consider the "canoncial problem" ...
    The Internet of Things is clearly many things: data collection and analytics, wearables, Smart Grids and Smart Cities, the Industrial Internet, and more. Cool platforms like Arduino, Raspberry Pi, Intel's Galileo and Edison, and a diverse world of sensors are making the IoT a great toy box for developers in all these areas. In this Power Panel at @ThingsExpo, moderated by Conference Chair Roger Strukhoff, panelists discussed what things are the most important, which will have the most profound e...
    Keeping pace with advancements in software delivery processes and tooling is taxing even for the most proficient organizations. Point tools, platforms, open source and the increasing adoption of private and public cloud services requires strong engineering rigor - all in the face of developer demands to use the tools of choice. As Agile has settled in as a mainstream practice, now DevOps has emerged as the next wave to improve software delivery speed and output. To make DevOps work, organization...
    My team embarked on building a data lake for our sales and marketing data to better understand customer journeys. This required building a hybrid data pipeline to connect our cloud CRM with the new Hadoop Data Lake. One challenge is that IT was not in a position to provide support until we proved value and marketing did not have the experience, so we embarked on the journey ourselves within the product marketing team for our line of business within Progress. In his session at @BigDataExpo, Sum...
    Web Real-Time Communication APIs have quickly revolutionized what browsers are capable of. In addition to video and audio streams, we can now bi-directionally send arbitrary data over WebRTC's PeerConnection Data Channels. With the advent of Progressive Web Apps and new hardware APIs such as WebBluetooh and WebUSB, we can finally enable users to stitch together the Internet of Things directly from their browsers while communicating privately and securely in a decentralized way.
    DevOps is often described as a combination of technology and culture. Without both, DevOps isn't complete. However, applying the culture to outdated technology is a recipe for disaster; as response times grow and connections between teams are delayed by technology, the culture will die. A Nutanix Enterprise Cloud has many benefits that provide the needed base for a true DevOps paradigm.
    What sort of WebRTC based applications can we expect to see over the next year and beyond? One way to predict development trends is to see what sorts of applications startups are building. In his session at @ThingsExpo, Arin Sime, founder of WebRTC.ventures, will discuss the current and likely future trends in WebRTC application development based on real requests for custom applications from real customers, as well as other public sources of information,