E mail Scriptlet

This example shows how to implement a flexible email notification system based on the scriptlet processor (gsn.processor.ScriptletProcessor). Thanks to the script, we can easily set and update the condition for sending an email as well as the email content itself. Prior to use this example, please configure the access to your SMTP account, as shown below and then set the recipient address in the script.

SMTP Configuration

The SMTP configuration is set in the file

conf/emails.properties

An example of configuration, using a GMAIL SMTP account is shown below:

# This file contains the properties for configuring the acces to a SMTP server in order to send emails.
# See the JavaMail API for constants for details -- http://java.sun.com/products/javamail/javadocs/index.html

# Configuration example for using the GMAIL SMTP server.
[email protected]
mail.smtp.password=**************
mail.smtp.host=smtp.gmail.com
[email protected]
mail.smtp.starttls.enable=true
mail.smtp.auth=true

Methods

Send an email to one or many recipients. Return true if the message has been succesfully sent, false otherwise.

boolean sendEmail(ArrayList<String> to, String object, String message);

Virtual Sensor Description File

This virtual sensor gets its data from the MemoryMonitorVS and sends a new email each time the MemoryMonitorVS.HEAP field reached a new maxima.

<virtual-sensor name="EmailScriptlet" priority="10">
    <processing-class>
        <class-name>gsn.processor.ScriptletProcessor</class-name>
        <init-params>
            <param name="persistant">false</param>
            <param name="scriptlet">
                <![CDATA[
                    // This script sends an email to alert that the heap value (from the local wrapper)
                    // has reached a new maxima.
                    // Please set your SMTP configuration (in the conf/emails.properties) prior to use this script. 

                    // Initialize the stateful variable maxima
                    if ( ! isdef('maxima'))
                        maxima = 0;

                    // Comparing the new heap size with the maxima
                    if (maxima < HEAP) {

                        maxima = HEAP;

                        // Notify by email
                        def emailTitle = "GSN Notification - New HEAP maxima reached: " + HEAP;
                        def emailContent = "Warning, the HEAP maxima has been reached: " + HEAP;
                        def recipients = ["[email protected]", "[email protected]", "[email protected]"]; // Define one or more recipients

                        sendEmail(recipients, emailTitle, emailContent); // note that the sendMail method is, by default, imported statically to the script.
                    }
                ]]>
            </param>
        </init-params>
        <output-structure/>
    </processing-class>
    <description>
        This Virtual Sensor demonstrates the use of the scriplet processor (gsn.processor.ScriptletProcessor) for email
        notifications. It gets its data from the MemoryMonitorVS and sends a new email each time the MemoryMonitorVS.HEAP field reached a new maxima.
    </description>
    <addressing/>
    <storage history-size="1"/>
    <streams>
        <stream name="stream1">
            <source alias="source1" storage-size="1" sampling-rate="1">
                <address wrapper="local">
                    <predicate key="name">MemoryMonitorVS</predicate>
                </address>
                <query>select * from wrapper</query>
            </source>
            <query>select * from source1</query>
        </stream>
    </streams>
</virtual-sensor>