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Showing posts from January, 2014

JVM Garbage Collection and Optimizations

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Overview When troubleshooting systems for performance-related issues, memory optimizations are a place that needs a deep analysis of what each system stores in the memory, how long those are stored, and access patterns. This post is to keep a note on the background information and valuable points to note in such an effort, specific to Java-based implementations as a deep understanding of the JVM behaviors is very beneficial in the process.

Java language provides much convenience to the developers by taking care of the memory management to a great extent letting the focus be on the rest of the logic. Still having a good understanding of how Java does this underneath, rationalize several best practices we follow in Java implementations and help design the programs better and think seriously on some aspects that can later lead to memory leaks and system stability in the long run. Java Garbage Collector has a big role in this been responsible for freeing up memory by removing memory gar…

Invoking APIs using a Web App with OAuth2 and use of JWT - WSO2 API Manager

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In this post I am to share my experience and understandings using WSO2 API Manager(API-M) for a very common and useful scenario in the industry. 
In brief following is the flow.

An API is exposed for app developers to be used under the control of API Manager (which adds access control for the API). Then app developers make their apps consuming those APIs. After development and testing is completed they make it available for end users at App store. The end users can then get registered in the store and use the apps with own credentials. The app will provide the desired services calling the APIs it has subscribed to.

The above scenario is well demonstrated in WSO2 API-M with the pizza shack example explained in the documentation at [1].




For clarity I will be including the steps in brief. For detailed steps we can refer documentation at [1]. 
API Developer Role We deploy the back-end services related to 'pizza ordering' in WSO2-Application server or any other desired application …

How to send an HTML email in Java (Using Google SMTP Server)

In most of the business services sometimes there comes requirements to send notifications to users or administrators via email.

For example :
Confirming a user registrationPassword reset via emails Following code segments can be used to send these emails using Google SMTP server. Here I am sharing two ways to do it.  Using javax.mail.jar directlyUsing Apache commons email jar which wraps javax.mail  Using javax.mail
try { Properties props = new Properties(); props.put("mail.smtp.host", "smtp.gmail.com"); props.put("mail.smtp.auth", "true"); props.put("mail.debug", "false"); props.put("mail.smtp.ssl.enable", "true"); Session session = Session.getInstance(props, new EmailAuth()); Message msg = new MimeMessage(session); InternetAddress from = new InternetAddress("sendersEmailAddress", "Sender's n…