Saturday, October 27, 2007
Standard MBeans and Documentation
This blog-post assumes that you are a Java Programmer and have used or at least have knowledge of JMX technology. If word JMX is not ringing the bell, and if you are a Java programmer, I strongly suggest you get to know this technology and I'm sure you won't regret that you did. Go here for more info.
JMX technology in Java ecosystem has been playing tremendous role in making the Java components more manageable and maintainable. If you are developing a Java component and are exposing the configuration/management through set of attributes/operations, most probably you would be using
Back to point. If you are using standard MBeans with an interface defining all attributes/operations and an implementation class to provide the functionality, I'm sure you would have noticed that attributes/operations on the JMX agents are not being displayed but just empty.
One would have put in enough effort to document the MBeans interface with all nitty-gritty details but it is would be of no use if it is not being displayed in the JMX agent view. This is due to fact that JMX agents are accessing your interfaces at runtime, by then Java compiler would have removed all javadocs and changed the parameter names for operations. However StandardMBeans provide set of hooks, which can show the appropriate documentation on the agent view.
Documentation hooks works by set of getDescription/getParameter methods on StandardMBean class before constructing the MBeanInfo object for your MBean. Where you can override those method to provide the documentation appropriate for your MBean, which would displayed on the agent view. However it is required to copy the documentation from MBean interface javadocs and programmatically return it. It is laborious and unmaintainable. Solution being, generate that class which can generate the documentation automatically from the MBean interface javadocs.
To my surprise I didn't find any tool/utility which can generate this java file automatically from the MBean interface and provides the documentation at runtime. So I decided to implement my own and release to public. It is MBeanDoclet.
MBeanDoclet automatically generates a java source file for set of MBeans and provides the same javadoc documentation at runtime. So if you modified the javadoc, it is automatically updated in JMX Agents.
Example worth ten-thousand words. So here is one. For ex., if we have a MBean named TestMBean with some nicely written documentation
Running the MBeanDoclet, generates the following file.
This automatic generated has added lots of value-add to the MBean we have been developing.
If this doclet can be of any useful, you can download here. If you have any questions/issues, mail be brsanthu[at]yahoo[dot]com.
Sunday, October 21, 2007
Poor Comcast Customer Service
A 70 year old woman from Bristow, VA took extreme measure to vent out the frustration of poor service from Comcast and went on to Hammer down the Comcat's office equipments. Well, I don't support her action of hammering down, Cable company should learn something from this to improve the service.
Read more here.
Saturday, October 06, 2007
Best of Adnan Sami
Do you like Adnan Sami's pop songs? Here is the You Tube play list of all his good songs. Enjoy!
Wednesday, October 03, 2007
Java Substring Caveat
It is one of the commonly used function in the java String class but many people don't realize the caveat associated with it.
When you call the substring on a String object, the implementation do NOT create a new char array that is backing it but shares it. Most of the cases this does work fine except in scenarios where you have a very large original String and want to keep reference to a part of that String.
Programmer would assume that newString has occupies memory to store 9 characters but truth is that it is 51 characters. This is due to the fact that when substring is called, Java String library didn't actually create a new character array of required length but used the same one created by originalString. This isn't an issue if you continue to keep the strong reference to the originalString as newString still does share same memory space but otherwise newString is using more memory than it should.
Is there a simple solution? There is.