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--- workflow:custom_function [2019/03/13 14:28]
admin created
+++ workflow:custom_function [2020/03/04 09:41]
admin
@@ Line 2: / Line 2: @@
 ~~Title: Custom function~~
-A function is behind the code block behind a task. It's very simple to create a new function because a function is defined as a single Java interface:
+A function is the code block behind a task. It's very simple to create a new function because a function is defined as simple Java interface:
 <file java IFunction.java>
@@ Line 8: / Line 8: @@
 {
     /**
-     * The current workflow step.
+     * Gets the current workflow step.
-     * @return The current workflow step.
+     *
+     * @return the current workflow step.
      */
     public IWorkflowStep getWorkflowStep();
@@ Line 16: / Line 17: @@
      * Initializes the function.
      *
-     * @param pWorkflow the current workflow step
+     * @param pStep the current workflow step
      */
-    public void init(IWorkflowStep pWorkflow);
+    public void init(IWorkflowStep pStep);
     /**
      * Runs the function.
-     * If the function returns true, the function is fully done, and the workflow jumps to the next step.
+     * If the function returns <code>true</code>, the function is fully done, and the workflow jumps to the next step.
      * In case there are more then one next steps, the finish function of IWorkflowStep has to be called.
      * An exception will be thrown otherwise.
-     * If finish is already called, it does not matter whether true or false is returned.
+     * If finish is already called, it does not matter whether <code>true</code> or <code>false</code> is returned.
      *
-     * @return true, if the function is done.
+     * @return <code>true</code>, if the function is done.
      * @throws Throwable if function fails.
      */
@@ Line 41: / Line 42: @@
 }
 </file>
+The interface already has an abstract implementation and so it's really super simple to create a new function. Our example will send an email, so it's the EmailFunction:
+<file java EmailFunction.java>
+public class EmailFunction extends AbstractFunction
+{
+    @Override
+    public boolean run() throws Throwable
+    {
+        XmlNode smtp = getApplicationZone().getConfig().getNode("/application/mail/smtp");
+        if (smtp == null)
+        {
+            throw new IllegalArgumentException("SMTP config not found (path /application/mail/smtp)!");
+        }
+        String host = smtp.getNodeValue("host");
+        String port = smtp.getNodeValue("port");
+        String username = smtp.getNodeValue("username");
+        String password = smtp.getNodeValue("password");
+        boolean tlsEnabled = Boolean.parseBoolean(smtp.getNodeValue("tlsenabled"));
+        String defaultsender = smtp.getNodeValue("defaultsender");
+        String from = getNotNullEvaluatedParameter("From");
+        String to = getNotNullEvaluatedParameter("To");
+        String cC = getEvaluatedParameter("CC");
+        String bCC = getEvaluatedParameter("BCC");
+        String subject = getNotNullEvaluatedParameter("Subject");
+        String body = getEvaluatedParameter("Body");
+        log("Mailserver: " + host + ":" + port + "/" + username);
+        Mail mail = new Mail(host, port, username, password);
+        mail.setTLSEnabled(tlsEnabled);
+        mail.send(CommonUtil.nvl(from, defaultsender), to, cC, bCC, subject, body, null, null);
+        log("From: " + CommonUtil.nvl(from, defaultsender));
+        log("To: " + to);
+        log("Subject: " + subject);
+        return true;
+    }
+}
+</file>
+The implementation is straight forward. It extends the AbstractFunction and implements run method. The email settings will be read from the [[jvx:common:setup:zones|application configuration]] and the email settings will be read from the input parameters. Finally, the email will be sent.
+But there's still one open question: How do we define the input parameters?
+Simply use the Functions screen and enter all required information:
+{{:workflow:wf_emailfunction.png?nolink|}}
+That's it. Start using your new function.