THE HELLO WORLD OF OUTPUT BUFFERING

So, you think that you have graduated from “hello world”, and know the basics of PHP well enough? Or do you? Let us revisit the very simple script again:

Ha. Child’s play, a piece of cake. The output is as expected, but let us now add output buffering to the equation.

What!? Isn’t this exactly the same as without output buffering? What is happening here and is this some kind of a joke? Is output buffering broken, or are the developer so bored that they have to create a troll function? Keep calm, and here is what happened.

• By default, PHP works without any sort of buffering; PHP is an impulsive fella who will send stuff to the output stream immediately.
• Without buffering, echo "hello" and echo " world" will get sent to the output stream instantly as they are being called. I.E. There are 2 different outputs in this case.
• But by enabling buffering, it is like telling PHP  – Stop it right there, you hasty bugger. Hold your horses on the output until I tell you to release it.
• So once we start the buffering, both echo "hello" and echo " world" will get collected into a buffer instead of directly into the output stream.
• Only at the end of the script will the buffer be released into the output stream. I.E. There is only one collective output in this case.

BUFFERING VS NONE

Maybe an illustration will explain things better.

WHAT IS IT GOOD FOR?

The uses of output buffering may not be very obvious at first, but without buffering, all the dynamic HTML and CSS that you generate with PHP will be sent out in bits-and-pieces.

• Turning on output buffering will decrease the amount of time it takes to download and render the HTML. Simply because it is no longer being sent in pieces, but as “one big chunk”.
• The even better part is when you save the buffer as a “completely rendered” HTML file. This will save your server resources from needlessly crunching the same pieces of data over-and-over again.
• You can also employ the same “save the buffer to a file” tactic on generated documents – PDF files, spreadsheets, and more.
• It is also kind of helpful when you deal with a function that echoes out values, that you rather store it somewhere else as a variable.

THE DISADVANTAGES

Yes, output buffering is not the perfect solution for everything.

• The output will only be released when everything is done – This may not be good for massive data crunching scripts, where you force the user to stare at an empty screen for a long time.
• Putting massive amounts of data into the cache also means consuming a lot of system memory.
• Output buffering does not really sense for real-time systems… You just want to output stuff quickly and instantly.

1) OB_START

As with the “hello world” example above, calling ob_start() will start the output buffering. All output after calling this function will be stored into an “invisible holding cell” buffer.

2) OB_CLEAN

ob_clean() will clean out everything in the output buffer, but take note that it will not output anything.

3) OB_FLUSH

ob_flush() will output the current buffer, then it will clean out everything inside it.

4) OB_END_CLEAN

ob_end_clean() will clear all the contents inside the current buffer, then stop the buffering.

5) OB_END_FLUSH

ob_end_flush() will output all the contents inside the current buffer, then stop the buffering.

6) OB_GET_CONTENTS

ob_get_contents() will return all the data inside the buffer.

7) OB_GET_CLEAN

ob_get_clean() will return all the data inside the buffer, then clean it out.

8) OB_GET_FLUSH

ob_get_flush() will return all the data inside the buffer, output it, then clean it out.

9) OB_GET_LENGTH

ob_get_length() will return the current size of the buffer, in bytes.

THE SCRIPT

 "John Doe",
    "email" => "[email protected]",
    "hobby" => "Football, Softball, Basketball, Racquetball, Baseball, Volleyball, Handball",
    "pets" => "Doge, Cate, Birb"
  ];

  // Buffer start
  ob_start();

  // Generate HTML ?>
  
  
    
      $v) {
          printf("", $k, $v);
        }
      ?>
%s
%s

THE EXPLANATION

This example should be pretty easy to understand – It puts a dynamically generated HTML page into the buffer, then saves it into an actual HTML file. The next time this page loads, it will grab that cached filed instead, and not redo all the dynamic generation again.

A pretty neat simple trick that will save you plenty of system resources. Combine this method with an HTML minifier, and this will give you quite a good speed boost as well.

THE SUMMARY

But of course, these are only a few of the common basics of output buffering. If you need more output buffering yoga – Please visit the official PHP function reference.

SOURCE CODE DOWNLOAD

Click here to download the example code, I have released it under the MIT license, so feel free to build on top of it or use it in your own project.
  

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