Like all protocols, HTTP involves a transfer of information between a client and a server. 1
The client and server are two remote entities that wish to communicate with each other. 2
The client makes request and the server answers. 3
There are many types of client and server. 4
For example, they are mail clients when we use POP and SMTP protocol. 5
There are files client and server when we use FTP protocol and of course there are web client and server 6
when we use HTTP protocols. In a client-server communication, 7
it's very important to know who is the client and who is the server. 8
In our case, we have two entities: the LoRaWAN server and the IoT platform, and depending on the situation, 9
we'll have to assign a role: 10
Sometimes the LoRaWAN Server will be the client and the IoT platform, the server, and sometimes it will be 11
the other way around. 12
The LoRaWAN Server will be the server and the IoT platform, the client. 13
Great. 14
So, I agree it's a little bit confusing because sometimes, the LoRaWAN Server can be the client, but 15
the term "server" in LoRaWAN Server only means that it serves the LoRaWAN protocol. 16
Once again here, we're not dealing with LoRaWAN anymore, but only with the transmission of the user 17
payload to the IoT platform. 18
OK, so each time we're going to deal with the dialogue between the LoRaWAN server on the IoT platform, 19
we will represent the LoRaWAN server at the top and the IoT platform at the bottom. 20
The LoRaWAN server can be any of the existing one. 21
So, TTN, Actility, LORIOT, ChirpStack, or any others, it really doesn't matter. 22
And at the bottom, the IoT platform can be the one we've built ourselves or any open sources or proprietary 23
ones available. 24
I'm not going to list the IoT platform available here, because there will be a specific chapter to build 25
our own. 26
Anyway, we now need to understand "who is requesting?" and "who is serving?" 27
For our explanation, we'll again use the same application described in the video at the beginning of this 28
lecture. 29
Sometimes, we'll send the string 30
"Hello". 31
But for some other demonstration we'll send the temperature. 32
And, when we'll deal with downlink, then we'll use the ability to turn an LED on or off. 33
Of course, the command will be managed from the IoT platform. 34
So, there are two situations to consider: 35
- UpLink: when the "hello" string or the temperature comes from the end-device. And - Downlink: when a switch 36
command comes from the user application on the IoT platform. 37
So, now we'll see in the next video two flavors of the HTTP protocol. 38
First, we can use the GET method. 39
Then we'll see the POST method of the HTTP protocol. 40
Let's start with the first method called HTTP GET.