JSONP. JSON with Padding

JSON is a really good solution to send data from server to client in web applications. Almost every program language has his own json encode and decode. PHP allows natively to do this encoding from php arrays and objets to JSON. And Zend Framework implements Zend_JSON who also allows you to encode/decode from XML.

When I was developing a rss client to my personal home page. I discover JSONP services. Those services are really easy to use and really easy to integrate them into your projects:

If the following url gives you a json data

url: http://www.server.com/service {“identifier”:”id”,”items”:[{“id”:”18″,”title”:” Asterisk. The future of telephony”,”author”:”Jim Van Meggelen”,”bookyear”:”2008″,”why”:””}]}

It is very helpfully when

url: http://www.server.com/service?callback=myfunction
myfunction({“identifier”:”id”,”items”:[{“id”:”18″,”title”:” Asterisk. The future of telephony”,”author”:”Jim Van Meggelen”,”bookyear”:”2008″,”why”:””}]})

with this if you develop the function ‘myfunction‘ with a few javascrip lines you can consume those jsonp webservices.

This is the source code I use to read

function googleSearch(bibkeys) {
  var scriptElement = document.createElement(”script”);
  scriptElement.setAttribute(”id”, “jsonScript”);
  scriptElement.setAttribute(”src”, “http://books.google.com/books?bibkeys=” + 
    bibkeys + “&jscmd=viewapi&callback=googleCallback”);
  scriptElement.setAttribute(”type”, “text/javascript”);
  document.documentElement.firstChild.appendChild(scriptElement);
}
function googleCallback(booksInfo) { // do what you want with the booksInfo }