HTTP Protocol
http://IP:42001/
Snap4Arduino comes with a built-in tiny HTTP server that mimics (and extends) the one Scratch 1.4 had. This means you can control your Snap4Arduino application from any computer, mobile phone, tablet or any other network-enabled device in the same network. In the following sections, the word IP refers to the IP address of the machine that has Snap4Arduino running on it.
Giving orders to Snap4Arduino
/broadcast=MESSAGE
Point your browser to http://IP:42001/broadcast=MESSAGE
This will broadcast the message MESSAGE to Snap4Arduino, where you can capture it with a regular When I receive [MESSAGE] block.
These public messages must begin with the + character. The rest of the messages are treated as private and thus are not accessible from the network.
Updating the value of a Snap4Arduino variable
/vars-update=VARIABLE-NAME=VARIABLE-VALUE
Point your browser to http://IP:42001/vars-update=VARIABLE-NAME=VARIABLE-VALUE
This will set the global variable called VARIABLE-NAME to the value VARIABLE-VALUE.
This only works for global variables that start with the + character. Any other variables are not editable. Bear in mind that variables with names containing the '=' character can not be used, even though Snap! supports them.
You can also update multiple variables at once by means of a POST request (see below).
Finding out which messages is Snap4Arduino listening for
/send-messages
Point your browser to http://IP:42001/send-messages
This will show a list of all message names for which Snap4Arduino has When I receive [message] hat blocks, as long as the message starts with the + character (other messages are private).
Getting variables and their values from Snap4Arduino
/send-vars
Point your browser to http://IP:42001/send-vars
This will show a list of all global variables defined in Snap4Arduino whose name starts with the + or with the - character (variables starting with + are editable, while variables starting with - are only readable), along with their current value.
Getting the value of a single variables from Snap4Arduino
/send-var=VARIABLE-NAME
Point your browser to http://IP:42001/send-var=VARIABLE-NAME
This will return the value of the variable ready for you to use, no string manipulation needed. The variable must start with the + or - character to be accessible from the network.
Getting a real-time stream of the stage in Snap4Arduino
/stage
Point your browser to http://IP:42001/stage
This will render a real time version of what's going on in the stage, like shown in this video.
You will be presented with an auto-refreshing HTML page, enabling you to watch the stage contents in your browser, though in a non-interactive way. You need to enable Public Stage from the settings menu for this to work. Otherwise, the stage is not accessible from the network.
Getting a snapshot of the stage in Snap4Arduino
/stageimg
Point your browser to http://IP:42001/stageimg
This will render a snapshot of the Snap4Arduino stage in the form of an image encoded in base64 that you can use for any purpose. You need to enable Public Stage from the settings menu for this to work. Otherwise, the stage is not accessible from the network.
POST. Updating multiple variables of Snap4Arduino from an HTML form
<form action="http://IP:42001" method="post">
You can update multiple global variables in your project at the same time by means of an HTML form sent through a POST request.
By using <INPUT> and <TEXTAREA> tags, you can send all kinds of input types to Snap!, except for booleans. Their name attribute should contain the name of the variable you wish to update.
Note that Snap4Arduino expects all queries to be UTF-8 encoded. To make sure your query goes through properly, especially when dealing with special characters, you can always use:
<form action="http://IP:42001" method="post" accept-charset="utf-8">