Long weekends reduce brain cells to jelly. Worked on a few things over the weekend, nothing really to report except write down this simple example.
The next book has far too many XML chapters in it, or at least it
seems that way at the moment. I had a good anti-WS-bloat rant in
Amsterdam recently. In a nutshell: most of the web services stack is
bloatware that doesn't get used for most applications. 90% of the time
you can get away with knowing no SOAP, WSDL, or any of that stuff. You
can just use REST - Representational State Transfer. This is basically
an HTTP GET request with parameters, and in return you get an XML
document, in other words XML over HTTP. It works very nicely and is
simple. I was trying to explain this to somebody here at work, so I
wrote a very basic REST server/client pair in PHP in five minutes to
demonstrate. Here's the code, which is doubled in size due to comments.
REST server for imaginary stock price lookup
restserver.php
1 <?php
2
3 // check which stock we want to look up
4 $stock = $_GET['stock'];
5
6 // look up the stock
7 $price = lookup($stock);
8
9 // format stock quote as XML
10 $string = "<stockquote><stockprice>$price</stockprice></stockquote>";
11
12 // make it into a proper XML document with header etc
13 $xml = simplexml_load_string($string);
14
15 // send an XML mime header
16 header("Content-type: text/xml");
17
18 // output correctly formatted XML
19 echo $xml->asXML();
20
21 // that's the end of the main code, function below is just a stub
22
23 function lookup($s)
24 {
25 // all stocks are worth $1 for this basic example
26 // but you would look it up in a database if you had one
27 return 1;
28 }
29
REST client demo
restclient.php
1 <?php
2
3 // query the REST server and load the returned XML as a PHP object
4 // note parameters go to REST server as HTTP GET parameters
5 $stock='MSFT';
6
7 $xml = simplexml_load_file("http://localhost/demo/restserver.php?stock=$stock");
8
9 echo "$stock stock price today is ";
10 echo $xml->stockprice;
11
12 ?>
13
14
Basically you don't need to know anything about Web Services or even
XML to make and consume REST Web Services. This assertion greatly
irritates a lot of people.
I'm not saying there isn't a need for SOAP and WS-*, just that often
simple tools will do the job. It's just another version of the 80%
rule. This seems to be a theme in my personal consumption of
technology.
posted on 2008-10-07 21:16
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