I want to build a java application(web dashboard) which will monitor different applications(independent java) running on different servers. Are there any open source application which I can use and modify for my usage. The features I am looking at are.
Zabbix may suit your needs. You can monitor application status with various preconfigured triggers which track processor load, idle time, loaded classes and more. Also can write custom triggers, for example, ping your web service every 3 min or notify occurred exceptions in Tomcat logs via email.