How to create a custom activity for journey builder?

Question

I am designing an email campaign for a company - AREXONE. For this, I am using the journey builder functionality of marketing cloud (exacttarget). But, while designing the workflow - I encountered a serious problem - how should I determine which audience have registered at my website - s682586167.websitehome.co.uk/axtria/marketingiq/portals/Portal%20Page%203%20-%20Sampling%20Site.html.
As you can see, my website is not hosted by salesforce and as such I can only feel that by creating a custom activity can I achieve my goal. Hence, I want to create a custom activity which can collect the data from my website in real time and update the DE to determine which audiences have registered to my website. I also wish to trigger send a confirmation email.

Note:- This is my first time designing a custom activity on journey builder, so please forgive me if I ask some stupid questions.

Note: I have tried to attempt at the above problem statement by creating a web-to-lead form in salesforce and then use marketing cloud connector to link the salesforce contacts with my synchronized data source in marketing cloud. But since a synchronized DE cannot be used in a journey builder and a filtered DE won't update its values once it enters the journey builder - I decided to try a different (and more convenient) method.

EDIT After deploying my app on heroku (using Markus' method), I am encountering an error when I test my journey.

My code is here.

At appcentre, in the application extension, the endpoint URL I specified was - "jb-custom-split.herokuapp.com" For jwt configuration, the jwt.js file has the code-

'use strict';

module.exports = (body, secret, cb) => {
    if (!body) {
        return cb(new Error('invalid jwtdata'));
    }

    require('jsonwebtoken').verify(body.toString('utf8'), secret, {
        algorithm: 'HS256'
    }, cb);
};

The sand key has been configured and added.

Answer 1

You can build a custom split activity which reads your website's data in the split's backend. The input argument of your custom split activity needs to be something identifying a customer on your website, which is also available in the journey. This could be the subscriber key or the email address, etc. Then the split's backend checks your websites database and returns the path accordingly.

I created something similar, that reads data from Salesforce Service Cloud. However, you can use the code and just have to swap the part reading from Service Cloud with code that reads from your database. My example includes a readme with all the steps necessary to set it up. You can find it on github.com/mslabina/sfmc-servicecloud-customsplit.

IMPORTANT: The documentation on creating journey builder split activities is rather outdated and the type you need to specify in the config.json is incorrect. You need to use RESTDECISION for a decision split to work.

Related documentation articles (that are partially outdated unfortunately):

• Create Custom Activities
• Create a Marketing Cloud App
• Go Further with Custom Activites