|By Frank Jennings||
|September 1, 2003 12:00 AM EDT||
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.
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.
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.
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.
|Florence 09/12/03 11:14:57 AM EDT|
|aviraj 09/11/03 10:57:05 AM EDT|
send me the latest news
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...
Jan. 27, 2015 06:15 PM EST Reads: 5,308
IoT is still a vague buzzword for many people. In his session at @ThingsExpo, Mike Kavis, Vice President & Principal Cloud Architect at Cloud Technology Partners, discussed the business value of IoT that goes far beyond the general public's perception that IoT is all about wearables and home consumer services. He also discussed how IoT is perceived by investors and how venture capitalist access this space. Other topics discussed were barriers to success, what is new, what is old, and what the future may hold. Mike Kavis is Vice President & Principal Cloud Architect at Cloud Technology Pa...
Jan. 27, 2015 06:15 PM EST Reads: 5,216
Dale Kim is the Director of Industry Solutions at MapR. His background includes a variety of technical and management roles at information technology companies. While his experience includes work with relational databases, much of his career pertains to non-relational data in the areas of search, content management, and NoSQL, and includes senior roles in technical marketing, sales engineering, and support engineering. Dale holds an MBA from Santa Clara University, and a BA in Computer Science from the University of California, Berkeley.
Jan. 27, 2015 06:00 PM EST Reads: 4,936
The Internet of Things (IoT) is rapidly in the process of breaking from its heretofore relatively obscure enterprise applications (such as plant floor control and supply chain management) and going mainstream into the consumer space. More and more creative folks are interconnecting everyday products such as household items, mobile devices, appliances and cars, and unleashing new and imaginative scenarios. We are seeing a lot of excitement around applications in home automation, personal fitness, and in-car entertainment and this excitement will bleed into other areas. On the commercial side, m...
Jan. 27, 2015 06:00 PM EST Reads: 4,653
"People are a lot more knowledgeable about APIs now. There are two types of people who work with APIs - IT people who want to use APIs for something internal and the product managers who want to do something outside APIs for people to connect to them," explained Roberto Medrano, Executive Vice President at SOA Software, in this SYS-CON.tv interview at Cloud Expo, held Nov 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA.
Jan. 27, 2015 02:30 PM EST Reads: 4,136
An entirely new security model is needed for the Internet of Things, or is it? Can we save some old and tested controls for this new and different environment? In his session at @ThingsExpo, New York's at the Javits Center, Davi Ottenheimer, EMC Senior Director of Trust, reviewed hands-on lessons with IoT devices and reveal a new risk balance you might not expect. Davi Ottenheimer, EMC Senior Director of Trust, has more than nineteen years' experience managing global security operations and assessments, including a decade of leading incident response and digital forensics. He is co-author of t...
Jan. 27, 2015 02:15 PM EST Reads: 4,648
Performance is the intersection of power, agility, control, and choice. If you value performance, and more specifically consistent performance, you need to look beyond simple virtualized compute. Many factors need to be considered to create a truly performant environment. In his General Session at 15th Cloud Expo, Harold Hannon, Sr. Software Architect at SoftLayer, discussed how to take advantage of a multitude of compute options and platform features to make cloud the cornerstone of your online presence.
Jan. 27, 2015 02:15 PM EST Reads: 4,926
SYS-CON Media announced that Splunk, a provider of the leading software platform for real-time Operational Intelligence, has launched an ad campaign on Big Data Journal. Splunk software and cloud services enable organizations to search, monitor, analyze and visualize machine-generated big data coming from websites, applications, servers, networks, sensors and mobile devices. The ads focus on delivering ROI - how improved uptime delivered $6M in annual ROI, improving customer operations by mining large volumes of unstructured data, and how data tracking delivers uptime when it matters most.
Jan. 27, 2015 02:00 PM EST Reads: 5,484
DevOps Summit 2015 New York, co-located with the 16th International Cloud Expo - to be held June 9-11, 2015, at the Javits Center in New York City, NY - announces that it is now accepting Keynote Proposals. The widespread success of cloud computing is driving the DevOps revolution in enterprise IT. Now as never before, development teams must communicate and collaborate in a dynamic, 24/7/365 environment. There is no time to wait for long development cycles that produce software that is obsolete at launch. DevOps may be disruptive, but it is essential.
Jan. 27, 2015 01:15 PM EST Reads: 3,946
Almost everyone sees the potential of Internet of Things but how can businesses truly unlock that potential. The key will be in the ability to discover business insight in the midst of an ocean of Big Data generated from billions of embedded devices via Systems of Discover. Businesses will also need to ensure that they can sustain that insight by leveraging the cloud for global reach, scale and elasticity.
Jan. 27, 2015 01:00 PM EST Reads: 5,716
How do APIs and IoT relate? The answer is not as simple as merely adding an API on top of a dumb device, but rather about understanding the architectural patterns for implementing an IoT fabric. There are typically two or three trends: Exposing the device to a management framework Exposing that management framework to a business centric logic Exposing that business layer and data to end users. This last trend is the IoT stack, which involves a new shift in the separation of what stuff happens, where data lives and where the interface lies. For instance, it's a mix of architectural styles ...
Jan. 27, 2015 12:30 PM EST Reads: 4,569
The Internet of Things will greatly expand the opportunities for data collection and new business models driven off of that data. In her session at @ThingsExpo, Esmeralda Swartz, CMO of MetraTech, discussed how for this to be effective you not only need to have infrastructure and operational models capable of utilizing this new phenomenon, but increasingly service providers will need to convince a skeptical public to participate. Get ready to show them the money!
Jan. 27, 2015 12:30 PM EST Reads: 4,501
The 3rd International Internet of @ThingsExpo, co-located with the 16th International Cloud Expo - to be held June 9-11, 2015, at the Javits Center in New York City, NY - announces that its Call for Papers is now open. The Internet of Things (IoT) is the biggest idea since the creation of the Worldwide Web more than 20 years ago.
Jan. 27, 2015 12:15 PM EST Reads: 4,755
Jan. 27, 2015 12:00 PM EST Reads: 10,093
"There is a natural synchronization between the business models, the IoT is there to support ,” explained Brendan O'Brien, Co-founder and Chief Architect of Aria Systems, in this SYS-CON.tv interview at the 15th International Cloud Expo®, held Nov 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA.
Jan. 27, 2015 11:45 AM EST Reads: 4,636
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...
Jan. 27, 2015 11:45 AM EST Reads: 4,344
The BPM world is going through some evolution or changes where traditional business process management solutions really have nowhere to go in terms of development of the road map. In this demo at 15th Cloud Expo, Kyle Hansen, Director of Professional Services at AgilePoint, shows AgilePoint’s unique approach to dealing with this market circumstance by developing a rapid application composition or development framework.
Jan. 27, 2015 11:30 AM EST Reads: 3,156
ARMONK, N.Y., Nov. 20, 2014 /PRNewswire/ -- IBM (NYSE: IBM) today announced that it is bringing a greater level of control, security and flexibility to cloud-based application development and delivery with a single-tenant version of Bluemix, IBM's platform-as-a-service. The new platform enables developers to build ap...
Jan. 27, 2015 11:15 AM EST Reads: 4,526
“The age of the Internet of Things is upon us,” stated Thomas Svensson, senior vice-president and general manager EMEA, ThingWorx, “and working with forward-thinking companies, such as Elisa, enables us to deploy our leading technology so that customers can profit from complete, end-to-end solutions.” ThingWorx, a PTC® (Nasdaq: PTC) business and Internet of Things (IoT) platform provider, announced on Monday that Elisa, Finnish provider of mobile and fixed broadband subscriptions, will deploy ThingWorx® platform technology to enable a new Elisa IoT service in Finland and Estonia.
Jan. 27, 2015 11:00 AM EST Reads: 2,386
Advanced Persistent Threats (APTs) are increasing at an unprecedented rate. The threat landscape of today is drastically different than just a few years ago. Attacks are much more organized and sophisticated. They are harder to detect and even harder to anticipate. In the foreseeable future it's going to get a whole lot harder. Everything you know today will change. Keeping up with this changing landscape is already a daunting task. Your organization needs to use the latest tools, methods and expertise to guard against those threats. But will that be enough? In the foreseeable future attacks w...
Jan. 27, 2015 11:00 AM EST Reads: 4,586