I discussed this part of the concept a lot with my coach. I didn't want you to have to create an account before you can send a message, this can sometimes be a barrier. If I would work with a login system I would work with Auth0 (an idea from Simon) or Firebase authentication.

The owner of the Christmas Tree 2.0 can then forward a link to the people who can 'control' his tree. Through this link, people must create an account, and only then can they send a message to the Christmas tree. A disadvantage of this system is that anyone can use the link to create an account and send a message. This can be solved in two ways: everyone gets a unique link with a hash or special parameter id at the end. Or the tree owner can add names or friends (like Facebook) via the online settings panel who can send things to his tree. Like a group with different roles, person y can send 2 messages per week, person z can send drawings to my tree... (Simon's idea).

This way is safe, but personally I don't find them as user-friendly and efficient. I also wanted to stay away from concepts like Facebook. Especially if grandma wants to send a message to the Christmas tree.

It is also possible that I leave out the entire login system. For example, a proud Christmas tree owner can send a unique link to a person.The link could look like this: 'mytree.com/?tree-owner=John?tree-id=123ABC?receiver=Cesar'. The danger here is that anyone with the link can send a message, and a link is quickly shared. This can be solved by including a unique code with each link. Before you can send a message you must first fill in the code, but that is again a code that you must keep track of...

Have I lost you in my thinking? That's okay, because through all the ideas above I came up with an idea that combines the most advantages and moreover fits the Christmas mood better.

If you order a Xmas tree 2.0, 6 Christmas globes are included as standard. On the back of the ball there is a QR code (and url for desktop users) and a 4 digit pin code. If you scan the QR code you have to enter a pin code. This can be saved with local storage so that you only have to enter the pin once. After this you can send a message to the Christmas tree. As an owner you can give a Christmas ball as a gift to your best friends, which can then be customised. You can always buy more baubles later. As a receiver you can hang the ball in your tree, so you never lose the (QR) code. As a bonus, the bauble can also contain electronics. For example, you can shake it, and then something appears on your friend's Christmas tree, but that's for later.