Lab 8a: Finger Client Finger is a straightforward protocol described in RFC 1288. The client makes a TCP connection to the server on port 79 and sends a one-line query; the server responds to the quer

Lab 8a: Finger Client

Finger is a straightforward protocol described in RFC 1288. The client makes a TCP connection to the server on port 79 and sends a one-line query; the server responds to the query and closes the connection. The format of the query is precisely defined, the format of the response is somewhat less so. All data transferred should be pure printable ASCII  text. The specification also recommends that clients filter out any non-ASCII data they do receive, at least by default. All lines must end with a carriage return/linefeed pair (\r\n in Java parlance).Use either of the following sites to learn more about it:

1)      www.faqs.org/rfc/

2)      www.ietf.org/rfc

Try the following scenario to get a feeling for it. The simplest allowable request from a client is a bare carriage return/linefeed pair, which is usually interpreted as a request to show a list of currently logged in users. For example, type in the following line and then hit return when the connection was established (that is providing the \r\n pair).

%telnet uisauth1.uis.edu 79

…

Your Lab 8a assignment is to write a Java finger client that allows users to specify a hostname on the command-line, followed by zero or more usernames. For example, a typical command-line will look like:

% java FingerClient hostname user1 user2 …

FingerClient connects to port 79 on the specified host using Socket class. Then use Socket’s OutputStream to send a line consisting of all names on the command-line, followed by a carriage return and a linefeed. Next, the output from the server (which is the input to your program) is taken from the Socket’s InputStream. Use appropriate filters for reading the server response as text. Display the server response on the user’s monitor.  You may test your program by fingering Directory.Purdue.edu as your hostname: Try java FingerClient Directory.Purdue.edu Sm