Click here to close now.

Welcome!

JAVA IoT Authors: Sematext Blog, Roger Strukhoff, Elizabeth White, Carmen Gonzalez, XebiaLabs Blog

Related Topics: JAVA IoT

JAVA IoT: Article

Accessing MBeans Through the Jini Service

Accessing MBeans Through the Jini Service

Network systems based on service discovery can provide a consistent view of their distributed components even during changing network conditions. The ability of a system to heal itself during a network catastrophe, including architectural change and system breakdown, will help the system to realign its content traversal route intelligently and swiftly. This ability can be obtained from various healing strategies like failure detection, consistency maintenance, and distributed service activation techniques.

A complete understanding of the interactions among self-healing strategies would provide architects of distributed systems with the knowledge necessary to build the most effective catastrophe-free network system with minimum overhead. A self-healing, manageable distributed system can be developed using a Jini federation. Since Jini is focused on service-oriented programming and supports the discovery of services, active or dormant, identifying service failure and recovering from a major disaster is possible.

As a rule of thumb, a network system is not complete if it's not manageable remotely. Hence there should exist a framework for exposing the application or Jini service for remote configuration. MBeans do just that.

Accessing MBeans from a different VM or a remote location can be done using a protocol adapter or connector. Connectors are similar to protocol adapters but they need the presence of a wrapper at both the server and the client sides; adapters are software, listening on the server side, built on a common protocol that the client is expected to understand and access. The JMX agent that starts the MBean server should let remote clients invoke methods on the MBeans registered in the MBean server.

The conventional way of accessing the MBean server from a different location is by using an RMI connector. RMI connectors are inherently MBeans registered in the MBean server. The remote client can access the MBean server using the RMI connector client. While this seems to be a neat solution for remotely accessing MBeans, the client needs to know the physical location of the MBean server. Even if the the MBean proxy is bound to a lookup, the client should know the lookup location. Even when using protocol adapters like the HTML and SNMP adapters, the client is expected to know the server location.

Consider a typical setup, such as a distributed content management system running on an agent framework, where the publishing server doesn't need to know where the content updating modules are running since it can be run by an editor, writer, or a designer in different locations. Implementing a simple connector does not solve this problem. This article explores the possibilities of using a discovery mechanism to find out where the JMX agent is running. This can be achieved by using a Jini connector, which is registered as an MBean with the MBean server.

However, we don't actually discover a running JMX agent but we discover the Jini lookup service that holds the proxy of the Jini service, which is also registered as an MBean with the MBean server. Figure 1 shows the MBean invocation process between two different VMs.

Management Through MBeans
An agent application is a piece of software written in Java that contains an MBean server and interfaces to access its functionality. This would be a minimal agent and anything less couldn't be managed. In our example of a minimal agent, we'll access the MBean server through the HTML protocol adapter from a Web browser and also through a Jini client running in a different VM. Jini is a Java-based network federation where the services that want to expose themselves to the clients register themselves with a lookup registry, and the client that needs to access the service discovers the service through the lookup registry and invokes its methods. Since MBean is not serializable, a Jini connector wrapper registers the proxy with the lookup service.

Discovering MBean Agents
A JMX client can access and manage MBeans exposed by the MBean agent running in a different VM through various known techniques. The JMX Remote API (JSR 160) proposes a viable solution to remotely access an MBean agent. Hence it's possible for a remote client to get a reference for the JMX Remote API Connector. But a JMX Remote API can be used only when you know where the MBean server is running. The standard does not provide any solution for discovering MBean agents. Instead, you can try traditional service discovery processes like Jini lookup and Service Location Protocol (SLP). SLP is an IETF standard that provides a framework for allowing networking applications to discover the existence, location, and configuration of networked services in the network. But the Java SLP Implementation (JSR 140) is still being tested.

Reggie for Discovering Agents
The Jini framework provides a reference implementation of a lookup ser- vice called "reggie" that holds service references and enables remote clients to discover it and get the remote service reference. It's very simple to discover a running Jini lookup service using API calls. The service, which intends to be a part of the Jini federation, registers a serializable object with the lookup service, enabling remote clients to use this object as a proxy. Another advantage of using Jini is that the classes required for instantiating the proxy objects can be downloaded dynamically from an HTTP server, and the Jini framework provides the necessary security for code download based on the RMI security manager. Figure 2 shows the classes being downloaded dynamically from the client in our example application.

Registering Services
In Jini the services can be registered through a serializable Java object or a stub. The stub provides a direct reference to the underlying Jini service. Since the Jini lookup service, which is based on RMI, automatically downloads from the server all the classes needed to deserialize the service object on the client, the server can register any class and the client can use the same class without having prior information of the class implementation. An easier way of registering services is by calling the JMXConnectorFactory .newConnector of the JMX Remote API.

Accessing Remote Agents
By using Jini, a JMX agent can be distributed the same way as an RMI connector, but without mandating that the clients know the location of the running agent. Hence, to access a JMX agent, the clients can just create a Jini connector and locate the nearest running agent. If multiple agents are running on the network, the clients can select which agent they want to access based on the lookup entry provided by the agent with the lookup service. The Jini connector can also advertise itself by using the default domain name of the MBean server in which it's registered.

In this article we'll build a simple Jini connector that registers itself with the MBean server and exposes the MBean agent for remote administration. Figure 3 shows the MBean list through an HTTP adapter showing the Jini connector and a configurable test string. The Jini connector is comprised of the service, which we want to register with the lookup service, the MBean, and a Jini client. Figure 4 shows the Jini lookup browser showing the Jini service class and the JiniWrapper registered with it. The MBean enables the agent to control the Jini service and, as you refer to the source code (which you can download from www.sys-con.com/java/sourcec.cfm), the MBean has a reference to the MBean server, which allows the Jini service to perform callbacks to the MBean server methods. The Jini client forwards its method invocation to the MBean server via the Jini service. The Jini client-side application discovers and uses the Jini connector service and therefore can use the agent.

An Example
The example source code provides a basic way of enabling the Jini client application to discover the lookup ser- vice running on the network and obtain the proxy of the Jini Connector service that enables the client to invoke the MBean server methods through callbacks. An excellent book to read, especially if you're new to Jini, is Jini in a Nutshell by Scott Oaks and Henry Wong; to learn the basics of JMX, read JMX in Action by Benjamin G. Sullins, Mark Whipple, and Ben G. Sullins.

The process of setting up a Jini environment can be frustrating at times. For this reason, I've provided some instructions (see sidebar). Though our service does not register with the RMI activation daemon, enabling auto-restart during crashes, the Jini lookup service, an activateable service, requires RMID running on the same VM. So make sure the lookup service and RMID are running in the same VM. The Jini connector service can be run in any VM as long as the correct server codebase is specified for dynamic classloading. When the client gets started, it finds out the lookup service and hence the agent, and tries to get the MBean registration information, MBean count, and the test string value. It also dynamically changes the value of the string that can be viewed in a browser (see Figure 2). The output of the client is shown in Figure 5.

Conclusion
MBean provides a powerful interface for managing services. Jini extends the functionality of MBeans by letting the client discover the JMX agent in a network on the fly. And since the agent is pulled into the Jini federation by the Jini connector service, other advantages like agent failure notification, event mailbox, and dynamic service reconfiguration are possible for attaining a true catastrophe free, self-healing, manageable, and intelligent network.

More Stories By Frank Jennings

Frank Jennings works in the Communication Designs Group of Pramati Technologies

Comments (2) 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
Florence 09/12/03 11:14:57 AM EDT

Hi Frank,
This article is so rich and informative. Hats off to you.
Hoping to see more articles with the same calibre.

aviraj 09/11/03 10:57:05 AM EDT

send me the latest news

@ThingsExpo Stories
Explosive growth in connected devices. Enormous amounts of data for collection and analysis. Critical use of data for split-second decision making and actionable information. All three are factors in making the Internet of Things a reality. Yet, any one factor would have an IT organization pondering its infrastructure strategy. How should your organization enhance its IT framework to enable an Internet of Things implementation? In his session at Internet of @ThingsExpo, James Kirkland, Chief Architect for the Internet of Things and Intelligent Systems at Red Hat, described how to revolutioniz...
The world is at a tipping point where the technology, the device and global adoption are converging to such a point that we will see an explosion of a world where smartphone devices not only allow us to talk to each other, but allow for communication between everything – serving as a central hub from which we control our world – MediaTek is at the heart of both driving this and allowing the markets to drive this reality forward themselves. The next wave of consumer gadgets is here – smart, connected, and small. If your ambitions are big, so are ours. In his session at @ThingsExpo, Jack Hu, D...
The security devil is always in the details of the attack: the ones you've endured, the ones you prepare yourself to fend off, and the ones that, you fear, will catch you completely unaware and defenseless. The Internet of Things (IoT) is nothing if not an endless proliferation of details. It's the vision of a world in which continuous Internet connectivity and addressability is embedded into a growing range of human artifacts, into the natural world, and even into our smartphones, appliances, and physical persons. In the IoT vision, every new "thing" - sensor, actuator, data source, data con...
All major researchers estimate there will be tens of billions devices - computers, smartphones, tablets, and sensors - connected to the Internet by 2020. This number will continue to grow at a rapid pace for the next several decades. With major technology companies and startups seriously embracing IoT strategies, now is the perfect time to attend @ThingsExpo, June 9-11, 2015, at the Javits Center in New York City. Learn what is going on, contribute to the discussions, and ensure that your enterprise is as "IoT-Ready" as it can be
SYS-CON Events announced today that MetraTech, now part of Ericsson, has been named “Silver Sponsor” of SYS-CON's 16th International Cloud Expo®, which will take place on June 9–11, 2015, at the Javits Center in New York, NY. Ericsson is the driving force behind the Networked Society- a world leader in communications infrastructure, software and services. Some 40% of the world’s mobile traffic runs through networks Ericsson has supplied, serving more than 2.5 billion subscribers.
The 4th International Internet of @ThingsExpo, co-located with the 17th International Cloud Expo - to be held November 3-5, 2015, at the Santa Clara Convention Center in Santa Clara, CA - announces that its Call for Papers is open. The Internet of Things (IoT) is the biggest idea since the creation of the Worldwide Web more than 20 years ago.
SYS-CON Events announced today that O'Reilly Media has been named “Media Sponsor” of SYS-CON's 16th International Cloud Expo®, which will take place on June 9–11, 2015, at the Javits Center in New York City, NY. O'Reilly Media spreads the knowledge of innovators through its books, online services, magazines, and conferences. Since 1978, O'Reilly Media has been a chronicler and catalyst of cutting-edge development, homing in on the technology trends that really matter and spurring their adoption by amplifying "faint signals" from the alpha geeks who are creating the future. An active participa...
We’re entering a new era of computing technology that many are calling the Internet of Things (IoT). Machine to machine, machine to infrastructure, machine to environment, the Internet of Everything, the Internet of Intelligent Things, intelligent systems – call it what you want, but it’s happening, and its potential is huge. IoT is comprised of smart machines interacting and communicating with other machines, objects, environments and infrastructures. As a result, huge volumes of data are being generated, and that data is being processed into useful actions that can “command and control” thi...
There will be 150 billion connected devices by 2020. New digital businesses have already disrupted value chains across every industry. APIs are at the center of the digital business. You need to understand what assets you have that can be exposed digitally, what their digital value chain is, and how to create an effective business model around that value chain to compete in this economy. No enterprise can be complacent and not engage in the digital economy. Learn how to be the disruptor and not the disruptee.
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 will peel 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 environment, and we must architect and code accordingly. At the very least, you'll have no problem fil...
There's Big Data, then there's really Big Data from the Internet of Things. IoT is evolving to include many data possibilities like new types of event, log and network data. The volumes are enormous, generating tens of billions of logs per day, which raise data challenges. Early IoT deployments are relying heavily on both the cloud and managed service providers to navigate these challenges. In her session at Big Data Expo®, Hannah Smalltree, Director at Treasure Data, discussed how IoT, Big Data and deployments are processing massive data volumes from wearables, utilities and other machines...
With major technology companies and startups seriously embracing IoT strategies, now is the perfect time to attend @ThingsExpo in Silicon Valley. Learn what is going on, contribute to the discussions, and ensure that your enterprise is as "IoT-Ready" as it can be! Internet of @ThingsExpo, taking place Nov 3-5, 2015, at the Santa Clara Convention Center in Santa Clara, CA, is co-located with 17th Cloud Expo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world. The Internet of Things (IoT) is the most profound change in personal an...
The worldwide cellular network will be the backbone of the future IoT, and the telecom industry is clamoring to get on board as more than just a data pipe. In his session at @ThingsExpo, Evan McGee, CTO of Ring Plus, Inc., discussed what service operators can offer that would benefit IoT entrepreneurs, inventors, and consumers. Evan McGee is the CTO of RingPlus, a leading innovative U.S. MVNO and wireless enabler. His focus is on combining web technologies with traditional telecom to create a new breed of unified communication that is easily accessible to the general consumer. With over a de...
Disruptive macro trends in technology are impacting and dramatically changing the "art of the possible" relative to supply chain management practices through the innovative use of IoT, cloud, machine learning and Big Data to enable connected ecosystems of engagement. Enterprise informatics can now move beyond point solutions that merely monitor the past and implement integrated enterprise fabrics that enable end-to-end supply chain visibility to improve customer service delivery and optimize supplier management. Learn about enterprise architecture strategies for designing connected systems tha...
From telemedicine to smart cars, digital homes and industrial monitoring, the explosive growth of IoT has created exciting new business opportunities for real time calls and messaging. In his session at @ThingsExpo, Ivelin Ivanov, CEO and Co-Founder of Telestax, shared some of the new revenue sources that IoT created for Restcomm – the open source telephony platform from Telestax. Ivelin Ivanov is a technology entrepreneur who founded Mobicents, an Open Source VoIP Platform, to help create, deploy, and manage applications integrating voice, video and data. He is the co-founder of TeleStax, a...
The Internet of Things (IoT) promises to evolve the way the world does business; however, understanding how to apply it to your company can be a mystery. Most people struggle with understanding the potential business uses or tend to get caught up in the technology, resulting in solutions that fail to meet even minimum business goals. In his session at @ThingsExpo, Jesse Shiah, CEO / President / Co-Founder of AgilePoint Inc., showed what is needed to leverage the IoT to transform your business. He discussed opportunities and challenges ahead for the IoT from a market and technical point of vie...
Grow your business with enterprise wearable apps using SAP Platforms and Google Glass. SAP and Google just launched the SAP and Google Glass Challenge, an opportunity for you to innovate and develop the best Enterprise Wearable App using SAP Platforms and Google Glass and gain valuable market exposure. In his session at @ThingsExpo, Brian McPhail, Senior Director of Business Development, ISVs & Digital Commerce at SAP, outlined the timeline of the SAP Google Glass Challenge and the opportunity for developers, start-ups, and companies of all sizes to engage with SAP today.
Cultural, regulatory, environmental, political and economic (CREPE) conditions over the past decade are creating cross-industry solution spaces that require processes and technologies from both the Internet of Things (IoT), and Data Management and Analytics (DMA). These solution spaces are evolving into Sensor Analytics Ecosystems (SAE) that represent significant new opportunities for organizations of all types. Public Utilities throughout the world, providing electricity, natural gas and water, are pursuing SmartGrid initiatives that represent one of the more mature examples of SAE. We have s...
The Internet of Things will put IT to its ultimate test by creating infinite new opportunities to digitize products and services, generate and analyze new data to improve customer satisfaction, and discover new ways to gain a competitive advantage across nearly every industry. In order to help corporate business units to capitalize on the rapidly evolving IoT opportunities, IT must stand up to a new set of challenges. In his session at @ThingsExpo, Jeff Kaplan, Managing Director of THINKstrategies, will examine why IT must finally fulfill its role in support of its SBUs or face a new round of...
One of the biggest challenges when developing connected devices is identifying user value and delivering it through successful user experiences. In his session at Internet of @ThingsExpo, Mike Kuniavsky, Principal Scientist, Innovation Services at PARC, described an IoT-specific approach to user experience design that combines approaches from interaction design, industrial design and service design to create experiences that go beyond simple connected gadgets to create lasting, multi-device experiences grounded in people's real needs and desires.