Blog
Articles, tutorials, and field notes on identity, integration, API management, and application security — spanning nearly two decades of hands-on work.
The Java Security Manager
In the last post, the Java Standard Edition and Java Enterprise Edition security features were introduced. This is the second in a series of articles that introduces each Java security feature in depth. This article introduces the Java Security Manager and the sandbox it creates for a Java…
Java Security — The Low-Level details To J2EE Security–And, Beyond
While researching details for a Java Security Manager article, it became obvious that I didn’t understand the mappings of all the different Java, security-related specifications to the technologies and acronyms I knew. Thus, was the beginning of this article. Below each security-related feature in…
Java Networking API vs. The C library networking API
The original article is located here. In this article, I described what was involved in writing a server program in the C language. The details are not important, but I wanted to compare the details that are exposed in this relatively simple C network programming example with the equivalent Java…
Concurrency And Server-Side Networking APIs — Part 4
The original article can be found here. Introduction
Concurrency And Server-Side Networking APIs — Part 3
This is part three of an exploration of how concurrency in networking APIs works in Unix-like operating systems and Java technology. This article now looks at the Java equivalents of several C-based server implementations that have been presented. If you haven’t read this series from the beginning,…
Concurrency And Server-Side Networking APIs — Part 2
In the second part of this series we continue to explore how Unix-like operating systems implement the networking API and threading API. In particular, we are supremely interested in how the kernel allows server programs accept incoming connections. Part two explores implementing concurrency in…
Concurrency And Server-Side Networking APIs — Part 1
This article explores how a Sun Hotspot JVM behaves when accepting incoming TCP/IP socket connections. The behavior of native server programs–written in C–are also explored to better understand how concurrency can be achieved. Then, a comparison of how these runtime environments implement…
Threads, Threads Everywhere. And, Not a Needle In Sight
Several terms have been used liberally throughout articles on thinkmiddleware.com. A moment should be taken to formally define them. I am going to attempt to present these concepts in as generic a sense as possible, but the truth of the matter is, every OS has its own threading model and…
Mapping An LWP Using Excessive CPU Time To a Java Thread
It happens. End users are complaining about a slow system or a request that never returned. You log into a production middleware server and notice that a java process is consuming an entire CPU or worst every available CPU on the box. It has happened again–a thread(s) has gone into an infinite loop…
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…