Archive for January, 2013

How to Read GIT Repository Using Java APIs

January 27th, 2013 12 comments

GIT is a source code control system created by Linus and others for managing Linux kernel development. It becomes one of the most popular version control systems especially in the open source community. Most developers use command line or the plugins to IDEs like Eclipse, NetBeans. I think even Microsoft VisualStudio has add-on for connecting to GIT, but I haven’t checked it.

Simple Logging in Java Application

January 21st, 2013 3 comments

Logging is a common requirement for application. In Java world, there are a few frameworks, the first and the most famous of which is the log4j from Apache foundation. Java included its own logging APIs afterwards. You can find many discussions which one is better in terms of use of use, flexibility, and performance. To reconcile the two APIs, a common abstraction called Simple Logging Facade for Java (SLF4J) was created. As SLF4J works with both log4j and Java logging, you can switch between them easily (in theory).

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Massive Scheduling with ScheduledExecutorService in Java

January 14th, 2013 2 comments

If you need to do certain things at certain points of time or intervals, you need scheduling capability. Don’t confuse the scheduling with multi-threading even though you can use multi-threading for scheduling but they are not equivalent. You can use single thread for many different tasks. Simply put, threads are executors, and tasks are jobs to be done by executors.

vSphere vs. Hyper-V: Difference of Virtual Machine States

January 6th, 2013 7 comments

While reading articles about Microsoft Hyper-V, I found that Hyper-V seemed to have different states for virtual machines from VMware vSphere. The virtual machine in Hyper-V is represented by the Msvm_ComputerSystem class. If you are familiar with VMware vSphere, you know the equivalent in vSphere is VirtualMachine. At first sight, the Hyper-V APIs may not look straight-forward. The Hyper-V APIs is actually based on Windows Management Instrumentation (WMI), which is essentially CIM from DMTF.

Cisco Nexus 1000V Distributed Virtual Switch: Command Line Examples

January 3rd, 2013 10 comments

I just took three day Cisco Nexus 1000V training before Christmas. It’s a pretty good experience to play with the commands in the VSM appliance although I am still not quite familiar with these commands yet. Nevertheless, I managed to run through all the 9 labs thanks to the online lab that I could access even after class. To help myself to remember what I did, I listed a few commands that often needed in managing Nexus 1000V.