IoT & Connectivity Tips

JavaMelody is an open source (LGPL) application that measures and calculates statistical information based on application usage. The resulting data can be viewed in a variety of formats including evolution charts, which track various operations and server attributes over time. There are also robust reporting options that allow data to be exported in either HTML of PDF formats. Installation Installation is fairly simple and can be done in just a few minutes. Download the distribution from JavaMelody Wiki and extract the javamelody.jar, available at https://github.com/javamelody/javamelody/releases Step 1: Download the java melody file (in unix, use the following command*): wget javamelody.googlecode.com/files/javamelody-1.49.0.zip Note: Ensure the latest version available at the link provided above before executing the unix command, modify the version accordingly. Step 2: Extract the zip file (using the following command in unix, note the version from step 1); unzip javamelody-1.49.0.zip Step 3: Copy the javamelody.jar and jrobin-x.jar from the javamelody installable to the WEB-INF/lib directory of the war file deployed in the tomcat using the following command in unix: cp -pr javamelody-1.49.0 jrobin-x.jar /opt/tomcat/server/webapps/<application name>/WEB-INF/lib Step 4: Edit the web.xml file from WEB-INF directory of the war file deployed in the tomcat and add the following lines in the web.xml before the description of the servlet.ie. mostly at the starting of the web.xml file.                 <filter> <filter-name>monitoring</filter-name>                <filter-class>net.bull.javamelody.MonitoringFilter</filter-class>        </filter>        <filter-mapping>                <filter-name>monitoring</filter-name>                <url-pattern>/*</url-pattern>        </filter-mapping>        <listener>                <listener-class>net.bull.javamelody.SessionListener</listener-class>        </listener> Step 5: Restart the tomcat server after editing the web.xml and access the javamelody page using the following url pattern: http://<hostname on which tomcat is configured>:<Port number on which the application is accessed>/<application name>/monitoring The url can be customized in the configuration file. Reports can be viewed in weekly, daily, or monthly formats. They can also be downloaded or can be sent over email in pdf format. iText library for WebApps and Java’s Mail and Activation libraries are required on the server in order to use the mail session. The report provides the same information that can be found in monitoring web page with both high-level and detailed information. CPU&Memory usage: Detailed SQL Information: SQL Statistics: Server Requests: System threads, caches: Data Caches: System Overhead ​On the JavaMelody Wiki, https://github.com/javamelody/javamelody/wiki/Overhead​ one can find a healthy discussion about system overhead. It seems that the general consensus is that  the overhead cost caused by JavaMelody is very low and that the feature is safe to enable full-time in QA environment. ->JavaMelody records only statistics and not events, so the overhead of memory is quite minimal. ->No  I/O on the wire and minimal I/O on disk. If no problem arises, it can be considered to enable JavaMelody on the production environment as well. Using a tool like JavaMelody can lead to valuable insights on how to optimize servers or uncover otherwise hidden issues, providing value that exceeds the overhead cost.

Background: Axeda Agents can be configured with standard drivers to collect event-driven data, which is then sent to the Platform. Axeda provides many standard event-driven data (EDD) drivers for use with the Axeda Agent (as explained in Axeda® Agents EDD Toolkit Reference (PDF)). All EDD  drivers are configured by an xml file and enabled in Axeda Builder, through the Agent Data Items configuration. You can configure an EDD driver to send important information from your process to the Agent, including data items, events and alarms. The manner in which you configure your drivers will affect the ability for your project to operate efficiently. Recommendation: Use drivers to reduce the amount of data sent to the platform. Instead of sending data items to the Platform, which then generates an event or alarm, it is possible to use the drivers to scan for specific data points or conditions and send an event or alarm. Before you can configure your agents, you first need to determine how often you will need your agent to send data to the Enterprise server. Two example workflows and recommendations: If you want to monitor a data item every second or two, configure the Agent to do the monitoring If you want to trend information once per day, perform that logic at the Enterprise Server. These examples may address your actual use case or your needs may fall somewhere in between. Ultimately, you want to consider that time scale (how often you want to monitor or trend data) and resulting data volume should drive how your system handles data. More data is available at the Agent, and at a higher frequency, then that needed at the Platform. Processing at the Agent ensures that only the important results are communicated to the Platform, leading to a “cleaner” experience for the Platform. Using this guidance as a best practice will help reduce network traffic for your customers as well as ensure the best experience for Enterprise users using server data in their dashboards, reports, and custom applications. Need more information? For information about the standard EDD Drivers, see the Axeda® Agents: EDD Drivers Reference (PDF).