Welcome!

Weblogic Authors: Yeshim Deniz, Elizabeth White, Michael Meiner, Michael Bushong, Avi Rosenthal

Related Topics: Weblogic

Weblogic: Article

Distributing Tasks in a Clustered Application Using JMS

Much more than asynchronous data transfer

Distributing Tasks in a Clustered Application Using JMS Much more than asynchronous data transfer

Decoupling and delaying processing in a request-driven environment is one of the key strategies in creating a robust and scalable distributed application. Many services rely on clustering alone to ensure scalability, but they frequently run into trouble when newfound requirements keep application complexity growing.

Although server clustering is an essential technology that facilitates scalability, it can be rather inefficient when all processing is done synchronously. Throughput can be increased, but responsiveness is a tougher nut to crack.

In this article, I discuss asynchronous processing and illustrate how clever task management can increase the performance, availability, scalability, and manageability of your application. We will create a generic task distribution framework that can send any task to either one or every server in your cluster, in a highly configurable fashion. Our framework will implement the well-known Command pattern by using polymorphism and the Java Message Service (JMS).

What Does Decoupling Mean in Practice?
When a server receives a client request, it usually needs to perform several individual tasks before a response can be returned. Decoupling means that instead of performing all tasks at once, some are instead queued and processed asynchronously. Because queuing is normally a low-cost operation, the synchronous request will finish quicker.

And the Benefits?
Processing tasks sequentially and in parallel is generally more efficient than processing them randomly (whenever clients happen to make requests). The positive impact is greater than what is immediately apparent. In theory, decoupling can increase performance in the following areas:

  • Robustness: Increases because requests will rely on fewer processes that can fail
  • Responsiveness: Partial post processing of requests decreases the time between receiving a request and returning a response
  • Scalability: All decoupled processes can grow in complexity without the threat of decreased responsiveness
  • Availability: Failures can be handled without the client ever knowing that something went wrong

Automatic retries are easily configured for situations where subsystems are unavailable.

Naturally, the difference between theory and practice will vary from application to application. However, it is clear that almost every implementation will have at least some of the aforementioned benefits.

Sounds Great, But Are There Any Pitfalls?
As with most good things, there are some caveats. One of the most severe is that you might actually find yourself decreasing availability if you don't ensure that you have enough hardware to clear busy processing queues. Queues grow very rapidly if more asynchronous requests come in than your system is able to process. Care has to be taken in the design, and automated monitoring of queues is certainly advisable. Another obvious problem is that most processes in request-driven environments aren't very good candidates for decoupling. In fact, most of the processing might be required to return a response. Sometimes it will require some out-of-the-box thinking and maybe even a change in the way you serve your clients.

Which Processes Can We Decouple?
From a purely technical perspective, nearly all processes can be decoupled. For instance, you can decouple an ordering transaction by queuing a list of purchased items together with customer details - the asynchronous process will take care of the rest. The downside is that you can't include any processing details in the response. Thus, meticulous prevalidation of data is important to ensure that nothing will go wrong.

An increasingly popular implementation is to queue requests immediately and then keep polling the server to know when a response can be retrieved. Although this approach is actually synchronous in nature and won't improve request processing times, it has the psychological benefit that a progress bar can be displayed during polling.

In addition to decoupling integral business logic (which can be a formidable challenge), less central processes such as logging and sending e-mail are very good candidates to consider. There is no reason to have a client wait for such tasks to complete when performance is of the essence. E-mail in particular is a very good candidate for decoupling. Let's have a closer look.

Case Study: Asynchronous E-mail
Sending e-mail the traditional way (as part of a synchronous request) poses some problems. First of all, connecting to an e-mail server requires a network round-trip and it might be slow, especially if the server is very busy. An overloaded e-mail server can even make a service that relies on e-mail temporarily unavailable.

XA Transaction Support
Another easily overlooked issue is that e-mail servers are commonly nontransactional by nature. This can cause inconsistent notifications when transactions are rolled back - a message can't be cancelled after it has been queued. Fortunately, JMS supports transactions and can fix this problem by delaying the delivery of a message until its underlying transaction is committed.

Take into account that when accessing the database and transaction-aware JMS, you will need to use XA and two-phase commit (2PC) transactions. It is possible to emulate XA with non-XA resources, but you might end up with inconsistent data. Enabling XA is a configuration issue and usually requires no changes in code. See the WebLogic documentation for details.

More Stories By John-Axel Stråhlman

John-Axel Stråhlman is the founder and CEO of Sanda Interactive Ltd (www.stc-interactive.com), a software consulting company based in Espoo, Finland. He is a distributed systems specialist and has been working as a consultant for his clients' projects for more than five years.

Comments (8) 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
John-Axel Strahlman 09/10/05 01:59:30 PM EDT

The source code for this article has been updated. You can access it by clicking on the source code link below the article.

John-Axel

mark sisson 08/30/05 12:43:57 PM EDT

I'm trying to find a download of sample code for this article but only found a SMALL link at the bottom of the article that is a link to a little snipet of code.

Is there a full blown example that accompanies this article? It is exactly what I've been looking for !!!

Thanks in advance.
mark

Charles Steinberg 05/24/05 03:26:05 PM EDT

John:
A question related to the configuration database for WLI 8.1: I am looking for documentation on the sizing of the WLI Database, vs. the Application database. Do you have any information to help establish a baseline?

John-Axel Strahlman 03/28/05 01:52:08 PM EST

Meir,

You need to configure JMS queues and write an MDB that does the asynchronous processing. The framework will only work on an application running on WebLogic Server 6.1 or newer. Drop me an email if you need more specific instructions.

The link to the performance guide is missing a slash between products and wlserver, sorry about that.

John-Axel

meir 03/24/05 04:02:49 PM EST

1.try to press on:

http://dev2dev.bea.com/productswlserver/whitepapers/WL_JMS_Perform_GD.jsp
and no response !!!

2.what kind of weblogic software needed to install?

3.how do i use this code:

Listing 3: Framework sample usage

DistributedLogger logger =
new DistributedLogger();

String text =
"Hello asynchronous execution!"

logger.setText(text);
TaskDistributor.execute(
logger, //Command instance
1000, //delay
true, //runEverywhere
false, //persisted
false, //enableXA
4); //delay.

i mean from a "main" program that includes "weblogic" classes?

Patricia Thomas 03/14/05 04:38:23 PM EST

We're also using JMS for several asynchronous tasks, but never thought of using a generic command processor like this. Until now, we have used dedicated queues and MDBs for each task, but this is clearly a better and more manageable solution! Thanks!

John-Axel Strahlman 03/01/05 03:33:24 AM EST

Yes, all your CommandMessage classes need to be in the classpath of the server (or servers) that does the execution.

Steve Rogers 02/28/05 02:50:21 PM EST

I assume each new type of CommandMessage, like the DistributedLogger, have to be in the Classpath of the Server. Otherwise, can the serialized objects method be executed?

@ThingsExpo Stories
DX World EXPO, LLC, a Lighthouse Point, Florida-based startup trade show producer and the creator of "DXWorldEXPO® - Digital Transformation Conference & Expo" has announced its executive management team. The team is headed by Levent Selamoglu, who has been named CEO. "Now is the time for a truly global DX event, to bring together the leading minds from the technology world in a conversation about Digital Transformation," he said in making the announcement.
"Space Monkey by Vivent Smart Home is a product that is a distributed cloud-based edge storage network. Vivent Smart Home, our parent company, is a smart home provider that places a lot of hard drives across homes in North America," explained JT Olds, Director of Engineering, and Brandon Crowfeather, Product Manager, at Vivint Smart Home, in this SYS-CON.tv interview at @ThingsExpo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
SYS-CON Events announced today that Conference Guru has been named “Media Sponsor” of the 22nd International Cloud Expo, which will take place on June 5-7, 2018, at the Javits Center in New York, NY. A valuable conference experience generates new contacts, sales leads, potential strategic partners and potential investors; helps gather competitive intelligence and even provides inspiration for new products and services. Conference Guru works with conference organizers to pass great deals to gre...
The Internet of Things will challenge the status quo of how IT and development organizations operate. Or will it? Certainly the fog layer of IoT requires special insights about data ontology, security and transactional integrity. But the developmental challenges are the same: People, Process and Platform. In his session at @ThingsExpo, Craig Sproule, CEO of Metavine, demonstrated how to move beyond today's coding paradigm and shared the must-have mindsets for removing complexity from the develop...
In his Opening Keynote at 21st Cloud Expo, John Considine, General Manager of IBM Cloud Infrastructure, led attendees through the exciting evolution of the cloud. He looked at this major disruption from the perspective of technology, business models, and what this means for enterprises of all sizes. John Considine is General Manager of Cloud Infrastructure Services at IBM. In that role he is responsible for leading IBM’s public cloud infrastructure including strategy, development, and offering m...
"Evatronix provides design services to companies that need to integrate the IoT technology in their products but they don't necessarily have the expertise, knowledge and design team to do so," explained Adam Morawiec, VP of Business Development at Evatronix, in this SYS-CON.tv interview at @ThingsExpo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
To get the most out of their data, successful companies are not focusing on queries and data lakes, they are actively integrating analytics into their operations with a data-first application development approach. Real-time adjustments to improve revenues, reduce costs, or mitigate risk rely on applications that minimize latency on a variety of data sources. In his session at @BigDataExpo, Jack Norris, Senior Vice President, Data and Applications at MapR Technologies, reviewed best practices to ...
Widespread fragmentation is stalling the growth of the IIoT and making it difficult for partners to work together. The number of software platforms, apps, hardware and connectivity standards is creating paralysis among businesses that are afraid of being locked into a solution. EdgeX Foundry is unifying the community around a common IoT edge framework and an ecosystem of interoperable components.
Large industrial manufacturing organizations are adopting the agile principles of cloud software companies. The industrial manufacturing development process has not scaled over time. Now that design CAD teams are geographically distributed, centralizing their work is key. With large multi-gigabyte projects, outdated tools have stifled industrial team agility, time-to-market milestones, and impacted P&L stakeholders.
"Akvelon is a software development company and we also provide consultancy services to folks who are looking to scale or accelerate their engineering roadmaps," explained Jeremiah Mothersell, Marketing Manager at Akvelon, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
"IBM is really all in on blockchain. We take a look at sort of the history of blockchain ledger technologies. It started out with bitcoin, Ethereum, and IBM evaluated these particular blockchain technologies and found they were anonymous and permissionless and that many companies were looking for permissioned blockchain," stated René Bostic, Technical VP of the IBM Cloud Unit in North America, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Conventi...
In his session at 21st Cloud Expo, Carl J. Levine, Senior Technical Evangelist for NS1, will objectively discuss how DNS is used to solve Digital Transformation challenges in large SaaS applications, CDNs, AdTech platforms, and other demanding use cases. Carl J. Levine is the Senior Technical Evangelist for NS1. A veteran of the Internet Infrastructure space, he has over a decade of experience with startups, networking protocols and Internet infrastructure, combined with the unique ability to it...
22nd International Cloud Expo, taking place June 5-7, 2018, at the Javits Center in New York City, NY, and co-located with the 1st DXWorld Expo will feature technical sessions from a rock star conference faculty and the leading industry players in the world. Cloud computing is now being embraced by a majority of enterprises of all sizes. Yesterday's debate about public vs. private has transformed into the reality of hybrid cloud: a recent survey shows that 74% of enterprises have a hybrid cloud ...
"Cloud Academy is an enterprise training platform for the cloud, specifically public clouds. We offer guided learning experiences on AWS, Azure, Google Cloud and all the surrounding methodologies and technologies that you need to know and your teams need to know in order to leverage the full benefits of the cloud," explained Alex Brower, VP of Marketing at Cloud Academy, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clar...
Gemini is Yahoo’s native and search advertising platform. To ensure the quality of a complex distributed system that spans multiple products and components and across various desktop websites and mobile app and web experiences – both Yahoo owned and operated and third-party syndication (supply), with complex interaction with more than a billion users and numerous advertisers globally (demand) – it becomes imperative to automate a set of end-to-end tests 24x7 to detect bugs and regression. In th...
"MobiDev is a software development company and we do complex, custom software development for everybody from entrepreneurs to large enterprises," explained Alan Winters, U.S. Head of Business Development at MobiDev, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
Coca-Cola’s Google powered digital signage system lays the groundwork for a more valuable connection between Coke and its customers. Digital signs pair software with high-resolution displays so that a message can be changed instantly based on what the operator wants to communicate or sell. In their Day 3 Keynote at 21st Cloud Expo, Greg Chambers, Global Group Director, Digital Innovation, Coca-Cola, and Vidya Nagarajan, a Senior Product Manager at Google, discussed how from store operations and ...
"There's plenty of bandwidth out there but it's never in the right place. So what Cedexis does is uses data to work out the best pathways to get data from the origin to the person who wants to get it," explained Simon Jones, Evangelist and Head of Marketing at Cedexis, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
SYS-CON Events announced today that CrowdReviews.com has been named “Media Sponsor” of SYS-CON's 22nd International Cloud Expo, which will take place on June 5–7, 2018, at the Javits Center in New York City, NY. CrowdReviews.com is a transparent online platform for determining which products and services are the best based on the opinion of the crowd. The crowd consists of Internet users that have experienced products and services first-hand and have an interest in letting other potential buye...
SYS-CON Events announced today that Telecom Reseller has been named “Media Sponsor” of SYS-CON's 22nd International Cloud Expo, which will take place on June 5-7, 2018, at the Javits Center in New York, NY. Telecom Reseller reports on Unified Communications, UCaaS, BPaaS for enterprise and SMBs. They report extensively on both customer premises based solutions such as IP-PBX as well as cloud based and hosted platforms.