Processing the result in Java

Make Quick Response Code in Java Processing the result

The processing is quite easy in this case because I simply want to copy the results of the PHP program directly to the output div: function processResult(data, textStatus){ $( #output )html(data); } The data parameter contains the text data returned from the AJAX call I simply grab that text and pass it to the output div

One of the nice things about AJAX is how it simplifies your server-side programming If you look back at greetUserphp, you ll see that it creates an entire XHTML page Most PHP programs work that way, creating an entire page every time However, because you re using AJAX, the PHP result doesn t have to be an entire Web page The PHP can simply create a small snippet of HTML Take a look at simpleGreetphp and you ll see it s very stripped down: < php $userName = $_REQUEST[ userName ]; print <p>Hi, $userName!</p> ; >

Although this program works just like greetUserphp, it s a lot simpler All it needs to do is grab the user name and print it back out The JavaScript function takes care of making the code go in the right place Without AJAX, each PHP program has to re-create the entire page When you re using AJAX, the HTML page stays on the client, and JavaScript makes smaller calls to the server The PHP is simpler, and the code transmission is generally smaller and faster, because there s less repeated structural information

Server-side work normally involves storage of data, as that s one thing that s easy to do on the server and difficult to do on the client Data can be stored in many ways: plain text files, HTML, or XHTML, or in a specialized system called a relational database (a specialized program that allows you to store and query data efficiently) The database approach is most common because it s incredibly powerful and flexible Normally programmers use a PHP program to request information from a Web page, and then use this information to prepare a request for the database in a special language called SQL (Structured Query Language) The data request is passed to the database management system, which returns some kind of result set to the PHP program The PHP program then typically builds an HTML page and passes the page back to the browser Data management is beyond the scope of this book See my Web site for more information about creating your own databases: wwwaharrisbooksnet The process can be easier when you use AJAX because the PHP program doesn t have to create an entire Web page All that really needs to be passed back to the JavaScript program are the results of the data query Normally, you do this using a special data format so the JavaScript program can easily manage the data

The XML format has become an important tool for encapsulating data for transfer between the client and the server If you re using XHTML, you are already familiar with XML XHTML is simply HTML following the stricter XML standard However, XML is much more than XHTML It can actually be used to store any kind of data For example, take a look at the following file (petsxml):

< xml version= 10 encoding= utf-8 > <pets> <pet> <animal>cat</animal> <name>Lucy</name> <breed>American Shorthair</breed> <note>She raised me</note> </pet> <pet> <animal>cat</animal> <name>Homer</name> <breed>unknown</breed> <note>Named after a world-famous bassoonist</note> </pet> <pet> <animal>dog</animal> <name>Muchacha</name> <breed>mutt</breed> <note>One of the ugliest dogs I ve ever met</note> </pet> </pets> If you look over petsxml, you can see it looks a lot like HTML HTML/ XHTML tags are very specific (only a few are legal) but XML tags can be anything as long as they follow a few simple (but familiar) rules: 1 Begin with a doctype Formal XML declarations often have doctypes as complex as the XHTML doctype definition, but basic XML data usually uses a much simpler definition: < xml version= 10 encoding= utf-8 > Any time you make your own XML format (as I m doing in this example), you can use this generic doctype 2 Create a container for all elements The entire structure must have one container tag I m using pets as my container If you don t have a single container, your programs will often have trouble reading the XML data 3 Build your basic data nodes In my simple example, each pet is contained inside a pet node Each pet has the same data elements (but that isn t a requirement) 4 Tags are case-sensitive Be consistent in your tag names Use camel case and single words for each element