C# 0 The Complete Reference

PART II

C h a p t e r   2 5 :  

N e t w o r k i n g   T h r o u g h   t h e   I n t e r n e t   U s i n g   S y s t e m . N e t    

841

              break;

            } else if(string.Compare(answer, "Q", true) == 0) {

              break;

            } else if(string.Compare(answer, "M", true) == 0) {

              Console.WriteLine("Searching for another link.");

            }

          } else {

            Console.WriteLine("No link found.");

            break;

          }

        } while(link.Length > 0);

        // Close the response.

        resp.Close();

      } while(uristr != null);

    } catch(WebException exc) {

      Console.WriteLine("Network Error: " + exc.Message +

                        "\nStatus code: " + exc.Status);

    } catch(ProtocolViolationException exc) {

      Console.WriteLine("Protocol Error: " + exc.Message);

    } catch(UriFormatException exc) {

      Console.WriteLine("URI Format Error: " + exc.Message);

    } catch(NotSupportedException exc) {

      Console.WriteLine("Unknown Protocol: " + exc.Message);

    } catch(IOException exc) {

      Console.WriteLine("I/O Error: " + exc.Message);

    }

    Console.WriteLine("Terminating MiniCrawler.");

  }

}

Here is a short a sample session that begins crawling at McGraw-Hill.com. (Remember, 

the precise output will vary over time as content changes.)

Linking to http://mcgraw-hill.com

Link found: http://sti.mcgraw-hill.com:9000/cgi-bin/query?mss=search&pg=aq

Link, More, Quit? M

Searching for another link.

Link found: http://investor.mcgraw-hill.com/phoenix.zhtml?c=96562&p=irol-irhome

Link, More, Quit? L

Linking to http://investor.mcgraw-hill.com/phoenix.zhtml?c=96562&p=irol-irhome

Link found: http://www.mcgraw-hill.com/index.html

Link, More, Quit? L

Linking to http://www.mcgraw-hill.com/index.html

Link found: http://sti.mcgraw-hill.com:9000/cgi-bin/query?mss=search&pg=aq

Link, More, Quit? Q

Terminating MiniCrawler.

Let’s take a close look at how MiniCrawler works. The URI at which MiniCrawler 

begins is specified on the command line. In