A message can be any string, that will be notified as is except for JSON strings.
JSON data using this format produce better looking notifications:
{
"title" : "title of the message", // default: "Notification"
"body" : "body of the message", // default: no body text
"icon" : "url to a small icon image", // default: no icon
"image" : "url to an image", // default: no image
"action" : "url to open when clicking the notification", // default: open this page
"silent" : true or false // default: false, not silent
}
This is an example message:
{
"title" : "Hello from PushService",
"body" : "This is a test message from PushService.",
"icon" : "https://www.esuli.it/images/ae64.png",
"image" : "https://www.esuli.it/images/andrea.jpg",
"action" : "https://esuli.it"
}