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Simple Server

Simple Server is a very basic HTTP server that supports a tiny sub-set of the HTTP specification in order for students to gain a better understanding of how the web works. Simple Server supports the following basic features:

  1. Accepts HTTP GET requests

    • allows user definition of the server web root
    • allows user definition of the port number
    • [ASSIGNMENT REQUIREMENT]: allows user definition of the default document
    • [ASSIGNMENT REQUIREMENT]: supports sub-directory sites

  2. Can handle response types for:

    • HTTP OK
    • HTTP NOT FOUND
    • HTTP METHOD NOT ALLOWED
    • HTTP INTERNAL SERVER ERROR

  3. Accepts GET request parameters

  4. Serves basic static mime-types:

    • various images (image/*) jpg, jpeg, png, gif, bmp, tiff
    • html (text/html) htm html
    • all other files will be served as application/octet-stream

  5. Support for dynamic web pages from basic C# scripts or web templates

    • the server will notify the user of compilation and runtime errors for processing scripts and templates in the response body of an HTTP Internal Server Error response

CScripts

So called CScripts will be processed to generate HTML content for a response. The following is a simple example of a CScript:

string foo = "My Great Script!!!";
wout.WriteLine("<html>");
wout.WriteLine("<body>");
wout.WriteLine("<h1>");
wout.WriteLine(foo);
wout.WriteLine("</h1>");
DateTime dt = DateTime.Now;
wout.WriteLine(string.Format("<p>The current time is {0}</p>", dt.ToString("MMM dd, yyyy hhh:mm:ss")));

string val = "not provided";

try {
	val = request["user"];
} catch ( Exception e ) {}

wout.WriteLine("The value of parameter user is {0}", val);

The server will provide an outputstream wout and the request parameter dictionary request. The using keyword is not supported, all classes must be fully referenced. The server will support use of any APIs in the System namespace. Class and method declarations are not supported.

CWebTemplates

So called CWebTemplates are basic web templates that allow C# to be embedded directly into HTML and processed by the server to generate a single HTML document. The following is a sample CWebTemplates:

<html>
	<body>
		{{
			string foo = "My Great Template!!!";
			DateTime dt = DateTime.Now;
		}}
		<h1>@{foo}</h1>
		<p>The current time is @{dt.ToString("MMM dd, yyyy hh:mm:ss")}</p>

		<span>The value of the parameter user is</span> @{request["user"]}
	</body>
</html>

The server will evaluate any C# code found between a set of double curly braces {{}}. Any SINGLE EXPRESSION found in @{} blocks will be written to the outputstream. The variable wout is not available to CWebTemplates as it is for CScripts. The request dictionary is made available.

Student Assignment

The master branch of the Simple Server does not contain an implementation of IScriptProcessor that will process CWebTemplates. Your assignment is to implement such a class and extend the webserver to utilize that class such that it will be capable of serving CWebTemplates. You should complete the following tasks:

  1. Update the web server to support default documents in the top-level and sub-directories of the web root. If a user browses to the root of a directory, the default file should be served and, if no default file exists, a 404 should be sent back to the browser.
  2. Write a class named CWebTemplateProcessor that implements IScriptProcessor, this class should be capable of processing CWebTemplate files.
  3. Update the WebServer class to serve CWebTemplates using the processor you developed in step 1. The server should be able to serve these files denoted with the .cweb extension. Your processor should be cabable of handling inline style and complicated block structures an example of which can be found below:
<html>
    <body>
        {{
            int i = !request.ContainsKey("i") ? 1 : Int32.Parse(request["i"]);
            int j = !request.ContainsKey("j") ? 10 : Int32.Parse(request["j"]);
        }}
        <h1>More Complicated</h1>
        <p>Let's try to count from @{i} to @{j}</p>

        {{
          if ( !request.ContainsKey("i") ) {
        }}
          <p style="color: red"><i>Oops, missing the i value, using @{i} as a default</i></p>
        {{
          }
        }}

        {{
          if ( !request.ContainsKey("j") ) {
        }}
          <p style="color: red"><i>Oops, missing the j value, using @{j} as a default</i></p>
        {{
          }
        }}

        <ul>
          {{
            for ( var pos = i; pos < j; pos++ ) {
          }}
            <li>@{pos}</li>
          {{
            }
          }}
        </ul>
    </body>
</html>