Go Daddy: Configure Apache HTTPd as a reverse proxy for Tomcat

Configuring Apache HTTPd as reverse proxy is one way to re-route requests to Tomcat from Apache. This post addresses how to do that for Dedicated Virtual Hosting at GoDaddy.com. Doing this requires simple configuration changes as described below:

1. Find httpd.conf file (usually located at /etc/httpd/conf).
2. Make sure the following lines are not commented in the file (by default they are not commented).
LoadModule proxy_module modules/mod_proxy.so
LoadModule proxy_http_module modules/mod_proxy_http.so
3. Add the following lines to enable the proxy to http.conf assuming you want to enable the servlet-examples webapps that comes with Tomcat installation (better to add at the end of the file):
ProxyPass /servlets-examples http://localhost:9080/servlets-examples
ProxyPassreverse / http://localhost:9080/
4. Restart Apache (using /usr/sbin/apachectl).

Now type http://www.yoururl.com/servlets-examples/ in your browser and you will be able to execute the Servlet samples.

Java is everywhere

Not sure how this is missed but SUN seem to have started posting to YouTube on how Java is Everywhere. Good PR to the minimum:

RIP Netscape Navigator

AOL has announced that its discontinuing support for Netscape Web Browser. Though it was just matter of when, somehow I still have nostalgic feelings and fond memories of Netscape. Without Netscape, Internet would not have been what it is today. Some of the contributions from Netscape are good and some are bad but when Internet history is being written Netscape would have a chapter of its own. Remember Netscape used to have "About the Internet" menu item instead of About Netscape?

Its sad that winners are out of business and losers are making Billions. When Microsoft started giving away IE free and embedded in windows it has 2 goals:
1. Destroy Netscape
2. Avoid paying to Spyglass (Spyglass's contract with Microsoft required Microsoft pay to Spyglass for using its code in IE only if Microsoft makes money on IE).
Microsoft accomplished both the goals and got sued by both Netscape and Spyglass. Both Netscape and Spyglass won in the court but are out of business today while Microsoft still makes Billions. The world is a strange place :-)

Amazon Kindle has JVM

Amazon Kindle seems to be heavy on Java. All the applications running seems to be developed in Java. From the look of the files existing on Kindle, it appears Kindle is using CDC and CVM. If Amazon opens up Kindle, it would become a great programming device for Java Developers soon and most widely available CDC device. According to Tritschler opening up kindle API's is a future direction.

Looking at contents of Kindle has the following files indicating its CDC based implementation:
/usr/java/bin/cvm
/usr/java/lib/jsse-cdc.jar


All the applications (Some of which are not made public exist as java applications based on existence of following jar files:

/opt/amazon/ebook/booklet:
AudiblePlayer.jar
AudioPlayer.jar
Browser.jar
ContentManager.jar
Demo.jar
Experimental.jar
Home.jar
MobiReader.jar
PictureViewer.jar
PrefBooklet.jar
Search.jar
XymlBooklet.jar
msp.jar


/opt/amazon/ebook/lib:
MobiCore-impl.jar
MobipocketCoreReader.jar
ReaderSDK.jar
SearchSDK.jar
framework-api.jar
framework-impl.jar
jdbm.jar
json.jar
kxml2.jar
xyml.jar

Amazon SimpleDB

Amazon added the final missing key ingredient to their online computing services Simple DB. Currently simple DB is in Limited Beta.

Thoughts based on initial read:
• Provides Web Service interface to Simple DB. Not traditional SQL.
• Provides Domains (Similar to Tables), Items (Similar to Rows) and Attributes (Similar to Columns).
• Provides Ability to create Domains, Get/Put/Delete items in Domains with attribute-value pairs for each item.
• Query can only be against a single Domain. (i.e Join’s are not possible).
• Currently Domain sizes are limited to 10GB.
• Similar to Google BigTable in design.

Serving Global Markets

Why Orkut is hugely popular in India compared to MySpace and Facebook which are popular in US? money.cnn.com has an interesting comment on the same that came from Nayak an young entrepreneur:

I asked him why he thinks Orkut is so much more popular in India than in the U.S. His answer suggested it might have something to do with Google's renowned technical capabilities. He points out that many of his friends get online at access speeds as slow as 15 kilobits per second. (About what AOL members in the U.S. were at in 1990.) His own dialup line is an only slightly-less-pokey 28K.
Nayak says "Orkut is much lighter than Facebook," meaning it is better designed to be used on a slow dialup line. While getting onto Orkut takes about a minute and a half for him, Facebook takes a minute longer. And getting on MySpace takes him five minutes.
Reference: CNN Money


In short be mindful of amount of data you are sending over the wire in web applications if you need to serve global markets.

Art of designing WSDL

Most common misconception is that Architect role ends at deciding what web services needs to be used. Designing web service by itself is an Art and doing it right provides:

• Maximize reuse of services
• Enforce better version control
• Better code generation
• Greater interoperability
• Increased testability

Here are some good resources on how to design good WSDL's:

• Using XML Schemas Effectively in WSDL Desgin
• XML Schema considerations for WSDL design in conformation with WS-I Basic Profile
• Best practices for Web services versioning
• Best practices for web services development