Learning Processing: A Beginner's Guide to Programming Images ...

19.4
void draw() {
background(255);
// Display message from server
fill(newMessageColor);
textFont(f);
textAlign(CENTER);
text(messageFromServer,width/2,140);
// Fade message from server to white
newMessageColor = constrain(newMessageColor + 1,0,255);
// Display Instructions
fill(0);
text( "Type text and hit return to send to server. ",width/2,60);
// Display text typed by user
fill(0);
text(typing,width/2,80);
// If there is information available to read
if (client.available() > 0) {
// Read it as a String
messageFromServer = client.readString();
// Set brightness to 0
newMessageColor = 0;
}
}
// Simple user keyboard input
void keyPressed() {
// If the return key is pressed, save the String and clear it
if (key == '\n') {
// When the user hits enter, write the sentence out to the Server
client.write(typing);
typing = " " ;
} else {
typing = typing + key;
}
}
Data Streams 363
Exercise 19-2: Create a client and server that talk to each other. Have the client send
messages typed by the user and the server respond autonomously. For example, you could use
String parsing techniques to reverse the words sent by the client. Client: “ How are you? ”
Server: “ You are how? ”
Broadcasting
The new message fades
to white by increasing
the brightness.
We know there is a message from
the Server when there are greater
than zero bytes available.
When the user hits enter, the
String typed is sent to the Server.
Now that we understand the basics of how clients and servers work, we can examine more practical uses
of networked communication. In the therapist client/server examples, we treated the data sent across the
network as a String, but this may not always be the case. In this section, we will look at writing a server
that broadcasts numeric data to clients.
How is this useful? What if you wanted to continuously broadcast the temperature outside your house or
a stock quote or the amount of motion seen by a camera? You could set up a single computer running a