java

Creating a webhook receiver using java

This is a simple Java HttpServlet that can receive incoming Webhook payloads, convert it to JSON format and write it to a file on disk.

Note : This guide assumes that servlet container is Apache Tomcat version 9 and Java SE Development Kit version 8 on Windows 10.

Step One: Install Java SE Development Kit 8 or later and Maven

• Install Java SE Development Kit 8 or later from Oracle.
• Once installed set the JAVA_HOME environment system variable.
• Verify Java installation by running below from a command prompt

C:\windows\system32> java -version
java version "1.8.0_144"
Java(TM) SE Runtime Environment (build 1.8.0_144-b01)
Java HotSpot(TM) 64-Bit Server VM (build 25.144-b01, mixed mode)

• Install Maven from Apache
• Add a MAVEN_HOME environment system variables, and point it to the Maven folder
• Add %MAVEN_HOME%\bin To PATH in system variables
• Check maven version

$ mvn -v
Apache Maven 3.6.1 (d66c9c0b3152b2e69ee9bac180bb8fcc8e6af555; 2019-04-04T12:00:29-07:00)
Maven home: C:\apache-maven-3.6.1

Step Two: Install a Servlet Container like Apache Tomcat and Enable SSL/TLS

• Install the Tomcat version 7 or later
• Since we need a Webhook receiver that support https traffic and that can communicate with Portal for ArcGIS you must enable SSL/TLS on your Servlet Container.
• Please follow steps here: Enable SSL/TLS. You will need to add a valid certificate to your Tomcat. Let's assume that you enabled port 8443.
• Start your tomcat

cd C:\apache-tomcat-9.0.14\bin
$ startup.bat

Step Three: Clone or download this repository, compile and run

• Download this repository. Let's assume that you have cloned to C:\ dir

git clone [email protected]:Esri/webhooks-samples.git

• Compile java class :

cd C:\webhooks-samples\developer\java\
$ mvn clean install

• Once compiled go to target\classes folder and copy WebhookListener.class

e.g. C:\webhooks-samples\java\receiver\target\classes\WebhookListener.class

• Paste your class under your tomcat's webapps\ROOT\WEB-INF\classes

e.g. C:\apache-tomcat-8.5.30\webapps\ROOT\WEB-INF\classes

• Edit web.xml under webapps\ROOT\WEB-INF and add below lines

<web-app>
  <display-name>Webhook Listener Web Application</display-name>
 <servlet>
   <servlet-name>WebhookListener</servlet-name>
   <servlet-class>WebhookListener</servlet-class>
</servlet>

<servlet-mapping>
   <servlet-name>WebhookListener</servlet-name>
   <url-pattern>/WebhookListener</url-pattern>
</servlet-mapping>
 
</web-app>

• Restart tomcat
• Now you should be able to access Webhook receiver by visiting https://<machine.domain.com>:8443/WebhookListener URL
• You should be able to see something similar to below on your browser

Step Four: Configure your Webhook with Receiver URL

Now you can use https://<machine.domain.com>:8443/WebhookListener URL as your payload URL when creating your webhook Any payloads received will be written to the c:\\temp\\webhookPayloads.txt file.