What are these media providers in whatsapp apis?

I have setup a two way communication between business account and customer using whatsapp business apis. I am having trouble understanding media providers that there documentation talks about for sending text message to customer with image/media.

Heres the link to it: https://developers.facebook.com/docs/whatsapp/api/settings/media-providers/

Who are these providers? are they some specified organisation?

I am currently storing the media files in AWS S3 using some pre-signed url method. Can I use media stored in S3 in whatsapp media message?.

An example would be great help.

According to the Whatsapp API media messages documentation, there are two ways of sending an image outbound message:

1. Send the image by its Media ID
2. Send the image by its URL

When choosing 2, sending it by its URL, sometimes you may need to setup a Media Provider settings if the images URL you reference is not directly accessible and requires a username/password authentication or even a bearer token. (check https://developers.facebook.com/docs/whatsapp/api/messages).

Sending images by Media ID

To send it by ID, you need first to upload the image file using the POST /v1/media endpoint. That will return the Media-ID (e.g: 456) that you should use to compose the message object on the POST /v1/messages/ endpoint, like this:

{
    "to": "1234567",
    "type": "image",
    "recipient_type": "individual",
    "image": {
        "caption": "The image caption",
        "id": "456"
    }
}

Sending images by URL

When sending it by URL, you can simply inform the URL of a image file (e.g.: http://yourcompany.com/images/your_image.png) on the link field of the POST /v1/messages/ endpoint, just like this:

{
    "to": "1234567",
    "type": "image",
    "recipient_type": "individual",
    "image": {
        "caption": "The image caption",
        "link": "http://yourcompany.com/images/your_image.png"
    }
}

What if the URL http://yourcompany.com/images/your_image.png is behind some authentication on the server? (username/password ou maybe a bearer token). Then you need first to setup a Media Provider with such credentials, using the POST /v1/settings/application/media/providers endpoint, like this:

[{
    "name": "yourcompany-images",
    "type": "www",
    "config": {
        "basic": {
            "username": "the-username",
            "password": "the-password"
        }
    }
 }
]

Once you have this set up on your API, then you are able to reference this Media Provider by its name on the POST /v1/messages/ endpoint, like this:

{
    "to": "1234567",
    "type": "image",
    "recipient_type": "individual",
    "image": {
        "caption": "The image caption",
        "link": "http://yourcompany.com/images/your_image.png"
        "provider": {
            "name" : "yourcompany-images"
        }
    }
}

Using S3 pre-signed URLs as image links

You have to consider that pre-signed URLs are temporary links that will expire after a while. It can work when everything is fine with you Whatsapp API Client and the message is promptly received by the recipient. But if something goes wrong on this chain, maybe the Whatsapp API will try to download the image again later. So keep this in mind and try to create pre-signed URLs with long expiration time (maybe a 7 day expiration link using IAM User as explained here).