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Peter Corke edited this page Sep 7, 2018 · 3 revisions

This example is in examples/webserver

user.m

function user() %#codegen
    webserver(8080, 'myserver');  % start webserver on port 8080
    sleep(60);   % hang around for a minute, then shutdown
function myserver()   % called on every page request
    switch (webserver.url())
        case '/'
            webserver.html('hello world');
        case '/bob'
            stllog('in /bob');
            webserver.html('<html><body>hello <b>from</b> /bob</body></html>');
            a = webserver.getarg('a');
            if ~isempty(a)
                stllog('a = %s', cstring(a));
            end
        case '/alice'
            vals.a = 1;
            vals.b = 2;
            webserver.template('templates/alice.html', vals);
        case '/duck':
            webserver.file('duck.jpg', 'image/jpeg');

The switch statement handles the particular URLs that are supported by the tiny webserver:

  • / sends simple text to the web browser.
  • /bob sends an HTML formatted string to the web browser and also demonstrates access to GET arguments (the things after the question mark on the end of a URL).
  • /alice sends the contents of the template file templates/alice.html and does the substitutions defined by the struct vals. The template variable a is replaced with 1 and so on. The numeric values are converted to strings using num2str which will convert a row-vector to a space separated sequence of numbers.
  • /duck return the contents of the data file with the content type image/jpeg which will be rendered in the web browser.

If the URL is not amongst the cases, or if no content is generated by a call to a webserver method a 404 error will be generated.

If the server is running on the same machine as the web browser, we can access it at localhost.

Access GET arguments: /bob

The page bob has the URL localhost:8080/bob and demonstrates how GET arguments can be accessed.

A request to the URL localhost:8080/bob generates the following log:

2018-09-05 08:49:41.514573 [WEB] web: GET request for URL /bob using HTTP/1.1
2018-09-05 08:49:41.514599 [WEB] in /bob

A request to the URL localhost:8080/bob?a=56 generates the following log: 2018-09-05 08:49:46.763896 [WEB] web: GET request for URL /bob using HTTP/1.1 2018-09-05 08:49:46.763931 [WEB] in /bob 2018-09-05 08:49:46.763936 [WEB] a = 56

A request to the URL localhost:8080/bob?a=hello generates the following log:

2018-09-05 08:49:54.570648 [WEB] web: GET request for URL /bob using HTTP/1.1
2018-09-05 08:49:54.570674 [WEB] in /bob
2018-09-05 08:49:54.570679 [WEB] a = hello

Note that the GET arguments are always strings. You can convert to numerical form using str2num which will return [] is the string is non-numeric.

Displays a templated HTML page: /alice

A request to the URL localhost:8080/alice processes the HTML template file

<html>
<body>
<p>This is a test page</p>
<p>a = <TMPL_VAR name="a"></p>
<p>b = <TMPL_VAR name="b"></p>
</body>
</html>

substituting (the TMPL_VAR tags) the values from the passed structure and generating this web page:

web page for /alice

Transfer an image: /duck

A request to the URL localhost:8080/duck shows an image of a duck, uploaded as image/jpeg content from the local file duck.jpg.

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