Waves

OTA means “Over The Air provisioning” – which also means downloading a Java ME app directly on your mobile phone. Therefore, OTA means, just plain downloading. That’s all!

But there are some problems. I developed a simple application using netbeans 6 and wanted to do a OTA deployment of the application. Hence, both the JAD & JAR files were uploaded to the web server. Now, I opened the web browser on my mobile and typed out the url of the JAD file. Usually, there is a property called on the JAD file called MIDlet-Jar-URL. It contains the link to the jar file. E.g. If suppose the JAD is located at http://aswinanand.com/app.jad, the MIDlet-Jar-URL in the JAD file will contain related properties of the JAR file including its download link. 

Hence, when a mobile identifies a JAD file, it will search for MIDlet-Jar-URL property, fetch the download link & download and install the application on your phone. What happened here was that, even though the JAD file was in perfect condition, it just got rendered as plain text on the mobile’s browser. The JAR was not downloaded and installed. Soon, I found out that the MIME type of JAD was different and that, for JAD files, “Content-Type” HTTP header has to be set to “text/vnd.sun.j2me.app-descriptor“. For JAR files, the “Content-Type” HTTP header has to be set to “application/java-archive“.

My web server runs apache. Hence, I just created a .htaccess file with the following entries:

1. AddType text/vnd.sun.j2me.app-descriptor .jad
2. AddType application/java-archive .jar

Now the JAD file was recognized perfectly by the phone :-). The JAR was downloaded and installed properly :D. More info on OTA can be obtained from here.