Welcome!

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

Related Topics: Machine Learning

Machine Learning : Article

Rich Internet Applications: Tips, Tricks & Techniques

How to Avoid Multiple Per-User Sessions in Tomcat/JBoss

Usually, in a rich internet application (RIA), a user with a registered account can do two different logins from two different workstations and can maintain two concurrent sessions opened. In some applications we want to limit the users to one session per account, so we have to take countermeasures.

A simple method to check if a user is logged is to set a property in the current HttpSession; in this example in our login function we set

session.setAttribute("username", username);

If there is no username attribute, we will return an error to the user.
When someone starts a session with his account we have to check if there is already a session opened with that account. We can use an HashMap using the username as key and the session as value; obviously we have to use the same hashmap across multiple logins. A very fast and simple solution is to create a singleton that exposes operations on our hashmap:

public class MySessionManager {

private HashMap hashMap;

public boolean exist(String username) {
if(hashMap.containsKey(username)) {
return true;
}

return false;
}

public boolean addSession(HttpSession session) {
if(hashMap.containsKey(session.getAttribute("username"))) {
return false;
}

hashMap.put((YouthruCorpPrincipal)session.
getAttribute("username"), session);
return true;
}

public HttpSession getSession(String username) {
return hashMap.get(username);
}

public boolean removeSession(String username) {
if(!hashMap.containsKey(username)) {
return false;
}

hashMap.remove(username);
return true;
}

private static MySessionManager instance;


public static MySessionManager getInstance() {
if(instance == null)
instance = new MySessionManager();

return instance;
}

public MySessionManager() {
hashMap = new HashMap();
}

}

In our login function we have to check the existence of a previously created session with the same username, in that case we can logout the user associated with that session:

if(MySessionManager.getInstance.exist(username)) {
logout(MySessionManager.getInstance.getSession(username));
MySessionManager.getInstance.removeSession(username);
}

In this case the logout function takes as argument a session and log out from our application the user associated with that session, then we can do our login routine and at add the current session to the hashmap.

In this example we are checking only for sessions with a username attached, if we want to do some operation every time a session is created/destroyed, we can implement the HttpSessionListener interface:

Classes that implement this interface will be notified of session creation and destruction using the respective functions:

void sessionCreated(HttpSessionEvent se)
void sessionDestroyed(HttpSessionEvent se)

To receive notification events, the implementation class must be configured in the deployment descriptor for the web application; for example:


<web-app version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/
j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">

<listener>
<listener-class>
myapp.security.MySessionListener
</listener-class>
</listener>
</web-app>

More Stories By Emanuele Tatti

Emanuele Tatti is a software engineer at Comtaste, a consulting company and solution provider for Rich Internet Applications (RIA) based in Rome, Italy, and operating internationally (www.comtaste.com/en). His areas of expertise are Flex, Livecycle Data Services, BlazeDS and Java for building enterprise applications. He has been involved in several projects especially related to the financial field and is also chief engineer for YouThruBiz, an innovative enterprise-class rich internet application which allows companies and recruiters to select human resources through multimedia job interviews and e-resumes.

His posts can be found at blog.comtaste.com

Comments (0)

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.


@ThingsExpo Stories
SYS-CON Events announced today that Enzu 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, 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. Enzu’s mission is to be the leading provider of enterprise cloud solutions worldwide. Enzu enables online businesses to use its IT infrastructure to their competitive ad...
The 21st International Cloud Expo has announced that its Call for Papers is open. Cloud Expo, to be held October 31 - November 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA, brings together Cloud Computing, Big Data, Internet of Things, DevOps, Digital Transformation, Machine Learning and WebRTC to one location. With cloud computing driving a higher percentage of enterprise IT budgets every year, it becomes increasingly important to plant your flag in this fast-expanding busin...
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.
SYS-CON Events announced today that delaPlex will exhibit at SYS-CON's @CloudExpo, which will take place on June 6-8, 2017, at the Javits Center in New York City, NY. delaPlex pioneered Software Development as a Service (SDaaS), which provides scalable resources to build, test, and deploy software. It’s a fast and more reliable way to develop a new product or expand your in-house team.
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 ...
Five years ago development was seen as a dead-end career, now it’s anything but – with an explosion in mobile and IoT initiatives increasing the demand for skilled engineers. But apart from having a ready supply of great coders, what constitutes true ‘DevOps Royalty’? It’ll be the ability to craft resilient architectures, supportability, security everywhere across the software lifecycle. In his keynote at @DevOpsSummit at 20th Cloud Expo, Jeffrey Scheaffer, GM and SVP, Continuous Delivery Busine...
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 Peak 10, Inc., a national IT infrastructure and cloud services provider, 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. Peak 10 provides reliable, tailored data center and network services, cloud and managed services. Its solutions are designed to scale and adapt to customers’ changing business needs, enabling them to lower costs, improve performance and focus intern...
SYS-CON Events announced today that Progress, a global leader in application development, 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. Enterprises today are rapidly adopting the cloud, while continuing to retain business-critical/sensitive data inside the firewall. This is creating two separate data silos – one inside the firewall and the other outside the firewall. Cloud ISVs ofte...
DevOps at Cloud Expo – being held October 31 - November 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA – announces that its Call for Papers is open. Born out of proven success in agile development, cloud computing, and process automation, DevOps is a macro trend you cannot afford to miss. From showcase success stories from early adopters and web-scale businesses, DevOps is expanding to organizations of all sizes, including the world's largest enterprises – and delivering real r...
SYS-CON Events announced today that Linux Academy, the foremost online Linux and cloud training platform and community, 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. Linux Academy was founded on the belief that providing high-quality, in-depth training should be available at an affordable price. Industry leaders in quality training, provided services, and student certification passes, its goal is to c...
SYS-CON Events announced today that Hitachi Data Systems, a wholly owned subsidiary of Hitachi LTD., 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. Hitachi Data Systems (HDS) will be featuring the Hitachi Content Platform (HCP) portfolio. This is the industry’s only offering that allows organizations to bring together object storage, file sync and share, cloud storage gateways, and sophisticated search and...
Internet of @ThingsExpo, taking place October 31 - November 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA, is co-located with the 21st International Cloud Expo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world. @ThingsExpo Silicon Valley Call for Papers is now open.
SYS-CON Events announced today that DivvyCloud 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. DivvyCloud software enables organizations to achieve their cloud computing goals by simplifying and automating security, compliance and cost optimization of public and private cloud infrastructure. Using DivvyCloud, customers can leverage programmatic Bots to identify and remediate common cloud problems in rea...
SYS-CON Events announced today that Tintri, Inc, a leading provider of enterprise cloud infrastructure, 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. Tintri offers an enterprise cloud platform built with public cloud-like web services and RESTful APIs. Organizations use Tintri all-flash storage with scale-out and automation as a foundation for their own clouds – to build agile development environments...
SYS-CON Events announced today that Fusion, a leading provider of cloud services, 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. Fusion, a leading provider of integrated cloud solutions to small, medium and large businesses, is the industry’s single source for the cloud. Fusion’s advanced, proprietary cloud service platform enables the integration of leading edge solutions in the cloud, including cloud...
SYS-CON Events announced today that Systena America 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. Systena Group has been in business for various software development and verification in Japan, US, ASEAN, and China by utilizing the knowledge we gained from all types of device development for various industries including smartphones (Android/iOS), wireless communication, security technology and IoT serv...
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 Carbonite 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. Carbonite protects your entire IT footprint with the right level of protection for each workload, ensuring lower costs and dependable solutions with DoubleTake and Evault.
New competitors, disruptive technologies, and growing expectations are pushing every business to both adopt and deliver new digital services. This ‘Digital Transformation’ demands rapid delivery and continuous iteration of new competitive services via multiple channels, which in turn demands new service delivery techniques – including DevOps. In this power panel at @DevOpsSummit 20th Cloud Expo, moderated by DevOps Conference Co-Chair Andi Mann, panelists will examine how DevOps helps to meet th...