Blog
Articles, tutorials, and field notes on identity, integration, API management, and application security — spanning nearly two decades of hands-on work.
Configure Your JVM For Use With a Remote Debugger
As I’ve pointed out in several previous articles, I like the jdb command line debugger that is available with the Sun JDK. This debugger can actually be used with any spec-compliant JVM. The JPDA specification defines the interfaces and services that are used by remote debuggers and profiles. The…
Generating Thread Dumps
Thread dumps are the basic diagnostic tool for JVMs. Thread dumps present a partial state of each Java thread in a running JVM. I say partial because it doesn’t present all information that captures the state of a Java thread. The state of a running Java thread is stored in a series of data…
My JVM ran out of memory! What objects are consuming all of the memory?
This article isn't a comprehensive JVM Java heap sizing and garbage collection tuning document; its goal is simply to outline options for identifying which type of Object(s) are consuming the majority of memory in a running JVM--troubleshooting memory leaks in the Java heap. As usual, I focus on…
Troubleshooting Deadlock Conditions With Monitor Locks In Java Virtual Machines
In this article, I wanted to present a brief tutorial regarding troubleshooting deadlock conditions in JVMs. Before one can troubleshoot a deadlock condition, one needs to understand what it is; to this end, I have written a simple Java program called DeadLock.java, which is guaranteed to very…
The Definition of Reverse Engineering, JVMs, and the Java programming language
I recently had a conversation with a colleague that reminded me of a another discussion with my Masters Project advisor a couple of years ago when I was exploring research topics. The topic under discussion was Reverse Engineering --in particular, Software Reverse Engineering. It sounds really…
EJB vs. Web Services
This article is by no means an exhaustive discussion on the subject of Web Services and EJBs. But, I have often found many of the points I bring up here missing from meaningful debate. Researching this article also gave me an opportunity to go over material I've been wanting to read for a while now.
The Java Instruction Set, Assemblers, and Disassemblers
Note: this is another article that I wrote a while ago using a Java Disassembler that no longer seems to be available--d-Java. There are numerous Java Disassemblers on the Internet. Two more that could be used are mentioned in the reference section: Jasper & Kimera. They can produce the Jasmin…
Generating Thread Dumps from a Sun or IBM JVM Running As A Windows Service
I was recently asked if there was a way to generate a Thread Dump from a JVM running as a Windows Service. It occured to me that I had a similar issue during my Masters Project when I was trying to generate a thread dump from a Cygwin xterm; Googling at the time turned up no good way of accomplishing the task. But, I knew that you could use the Java Debugger that ships with the Sun JDK, jdb, to generate a thread dump of all non-System Threads in a JVM. I posed this as a solution to generating Thread Dumps from a JVM running as a Windows Service.
Performance Tuning In Industry
IT Professionals face an up hill battle in the realm of performance tuning. First, management must be convinced that time needs to be set aside for it. Next, the skill sets to successfully move through the performance tuning life cycle must be present. Then, the tools to effectively identify issues…
Part 2: Custom Client-Server Java Application That CommunicatesOver A Mutually Authenticated SSL (MASSL) Connection
This is the second of a two-part series discussing Java and Mutually Authenticated SSL. This will gave you a taste of how a J2EE container is communicating (over SSL or MASSL) behind the scenes.
Part 1: Creating your own SSL certificates for a custom Java client-server application
If you replace the steps for creating your own CA private key & certificate and signing your own certificate (with the CA) with having certificates signed by a legitimate Certificate Authority, you've got the basic idea behind creating/ordering certs for most situations.
Achieving highly available HTTP database session persistence spanning multiple cells with Websphere v6.1
Websphere can provide HTTP Session data replication across multiple clusters and cells by using database session persistence.