Description
This assignment emphasizes client-server programming using the TCP protocol. This individual
student assignment is to write both a TCP client and a TCP server in C or C++ using Linux socket
commands. The Medical Examiner Clients and the Medical Examiner Server must execute on
different CCC machines and communicate with each other using TCP.
Medical Examiner Disaster Identification Database (DID) Concept
FEMA needs a database and a client/server paradigm to create and access a repository for
information about bodies collected during and after a natural disaster. Authorized FEMA employee
clients need the ability to input information such as photos, fingerprints, dental records and tattoos
that could facilitate identification of a body recovered after events such as a flood, earthquake or
tornado. Acting on behalf of a qualified medical examiner, the FEMA employee can input that a body
has been positively identified (i.e., full name is input) or that the identification is unknown (i.e., UNK
for first and last name). Each body will have a unique ID code assigned and a location where
emergency personnel recovered the body. Family members seeking information about missing
loved ones ONLY have the ability to query the database.
Assume FEMA has advertised for contract bids to implement a simplified prototype for this networkbased system that includes a simple Disaster identification Database (DID) with a maximum of 100
body entries in a simplified in-memory data structure. Your program submission should convince
FEMA to hire your company to implement the full Medical Examiner network Application and
database.
Preliminary Medical Examiner (ME) Clients
The prototype network application supports two types of clients (authorized and query) where
authorized clients handle FEMA employee functions for the DID and query clients handle family
queries into the DID.
The Medical Examiner (ME) client functionality should be designed to take test input either as a
series of single line commands from standard input or from an input file, MEClient.txt. The ME Client
provides an interface to the ME Server that sends proper commands and receives all responses from
the ME Server and prints them out to the standard output or writes them to a file, LClient.log.
The ME Client should run on any arbitrary CCC Linux machine. The command line for initiating the
client is:
./my_MEClient MEServermachine MEClient.txt
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where
MEServermachine indicates the logical name for the server machine (e.g.,
CCCWORK4.wpi.edu).
and
MEClient.txt indicates that data is to be read from this text file. If this field is not specified,
the ME Client reads command line input from standard input (the keyboard).
The ME Client communicates with the ME Server assuming knowledge of a unique “well-known”
port. The ME Client accepts and relays one of the following commands to the ME Server.
ME Client commands
The following two commands identify the beginning and end of a simulated, prototype
client:
login name
Upon receiving login, the ME Client determines first whether the user is authorized to input changes
(adds, removes or updates) to the DID or that the user can only issue query requests.
For this prototype assignment, the only two legal names are: “FEMA” for an authorized user or
“Query” to indicate that this user that can only issue query commands. The ME Client is responsible
for assuring that each command issued to the ME Server satisfies the proper authorization level. The
ME Client establishes a TCP connection for name to the ME Server.
quit end-of-file
Upon receiving quit, the ME Client indicates to the ME Server to close name’s TCP connection to the
ME server.
where
end-of-file is an optional argument indicating whether another client script follows in the
input stream.
When end-of-file is specified via the string “EOF”, once the ME Client receives a response from the
ME Server, the ME Client closes the log file and terminates. When end-of-file is not specified, the ME
Client and the ME Server both assume that another client script follows quit. Note – authorization
does not run across quit commands.
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The following are three commands that only a FEMA user can issue:
add id_number first_name last_name gender location
where
id_number is a 9-digit identification number.
first_name is a non-blank ASCII string with maximum length of 20 characters.
last_name is a non-blank ASCII string with maximum length of 25 characters.
gender is a single character string. ‘M’ indicates a male and ‘F’ indicates a female.
location is a non-blank character string (30 character max) indicating the person’s current
location.
Add inserts a new record into the DID. If the body has been identified both the first_name and the
last_name must be included in the add command. If the ID of the body is currently unknown then
both name fields will contain the string “UNK”. All fields are required.
update id_number first_name last_name gender location
where
id_number is a 9-digit identification number.
first_name is a non-blank ASCII string with maximum length of 20 characters.
last_name is a non-blank ASCII string with maximum length of 25 characters.
gender is a single character string. ‘M’ indicates a male and ‘F’ indicates a female.
location is a non-blank character string (30 character max) indicating the person’s current
location.
Update changes information for an existing id_number. All fields are required. Note ID numbers
are unique while names are not in the DID.
remove id_number
where
id_number is a 9-digit identification number.
Remove eliminates the record associated with the id_number from the DID.
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The following are the query commands that any user can issue:
find first_name last_name
where
first_name is a non-blank ASCII string with maximum length of 20 characters.
last_name is a non-blank ASCII string with maximum length of 25 characters.
Find is a query command that searches for only one name in the DID.
list start finish
where
start is a one character ASCII alphabetic character string.
finish is a one character ASCII alphabetic character string .
List is a query command that lists records within a name range.
locate location
where
location is a non-blank character string (30 character max) indicating a possible location
in the disaster region.
Locate is a query command to obtain information about all bodies at one location.
The ME Server
The ME Server starts first and waits for a connection request from a single ME Client stream. The ME
Server maintains an in-memory location database that keeps track of the locations of all the people
added to the database by the ME Client. The database is maintained in alphabetical order by
last_name. Unidentified bodies are located at the back of the database behind all the identified
bodies. All name strings in the legal commands are case-insensitive. {Note – the data structure
implemented is the student’s choice, but the suggestion for this assignment is to keep it simple!}
ME Server Responses
The following define the response actions of the ME Server to each of the valid commands sent via
TCP messages by the ME Client:
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login
Upon receipt of login, the ME Server returns a Hello name! message back to the client process.
name is the specified login name.
add
Upon receipt of the add command, the ME Server adds the five items as an entry into the location
database in the proper location.
The ME Server checks for duplicates. Namely, if a duplicate id_number is received via an add
command, the server sends an error message back to the client that indicates the id_number is
already stored in the database. The goal of the ME Server is to maintain the location database in a
manner that facilitates listing the locations of people in alphabetical order by last name. Note, add
commands with identical first and last names are NOT duplicates if they have unique id_numbers.
Identical names should be stored in the chronological order of the add function.
The Me Server sends back a copy of ALL the information sent as an indicator of a successful entry
into the DID.
For simplicity of design assume that the maximum number of entries in the DID is 100.
update
Upon receipt of the update command, the ME Server replaces the four items associated with an
id_number that already exists in the DID. The ME server returns an error message if the id_number
is not found in the DID.
remove
Upon receipt of the remove command, the ME Server searches the database for a match on
id_number. If the id_number entry exists in the database, that entry is removed from the DID and a
success message that contains the last and first name of the person removed is sent back to the ME
Client. If there is not a match in the database, the server does not modify the database and sends an
appropriate error message back to the ME Client.
find
Upon receipt of a find command, the ME Server searches the database for all entries that match the
first and last name. The server returns all the information associated with any matches. Each
database entry is sent as a separate TCP message back to the ME Client.
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list
Upon receipt of the list command, the ME Server sends back to the ME Client all DID entries in the
database currently within the range of the list limits. Each database entry is sent as a separate TCP
message back to the ME Client. The entries sent back contain all of the entry information for those
entries in the database where the last_name begins with the start character and is less than or equal
to the finish character. The finish character is optional. If only a start character is specified, the ME
Server sends back all entries in the database where the first character of the last name matches the
single letter string. If neither start nor finish are specified, the ME Server returns the complete
database in alphabetical order. If finish is lower in the alphabet than start, the server returns an
error message. If the database currently holds no entries satisfying the range of the specific list
request, the ME Server sends back an indication that there are no entries satisfying the list request.
List does not return information for any of the unidentified bodies (UNK).
locate
Upon receipt of the locate command, the ME Server sends back to the ME Client all DID entries in the
database that currently match the specified location in alphabetical order. Each database entry is
sent as a separate TCP message back to the ME Client. This query request does include all the
unidentified body information found at the location indicated. Note, location is case-insensitive.
quit
Upon receipt of quit, the ME Server sends a response back to the ME Client indicating that the TCP
connection will be closed for name and include a count of the number of commands that name
issued to the server. The ME Server prints out a count of the number of TCP packets it sent to name.
After closing the connection, the ME Server then returns to wait for a new connection triggered by a
subsequent login request from the ME Client. The end-of-file field is optional. If this field contains the
text “EOF”, the ME Server additionally writes out the complete database to the file MEDatabase.txt
and sends back to the ME Client a count of the number of client scripts processed and the total
number of TCP packets that the ME Server sent . The server then terminates.
Do not wait for the official test data to work on this assignment. Work with your own test data
initially. The ME Client needs to be able to read directly from a test file MEClient.txt. Your client must
also write out ME Client commands issued and ME Server responses out to the MEClient.log file.
What to turn in for Program 1
An official test file will be made available a couple of days before the due date. Turn in your
assignment using the turnin program. You should turn in a tarred file that includes: all the source
programs for MEClient and MEServer, a README file and a make file. You can optionally also turn in
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the MEClient.log in the tarred file. The README file should include any special directions needed to
execute your ME Client and Server on separate CCC machines. README should also contain a clear
indication of the state of your program when you turn it in. This includes current limitations and
parts of the assignment that are not working correctly. Indicate clearly all commands that work
completely, partially and not at all!
Programming Hints
Below is a list of possibly useful C function calls for Program 1.
Note – you will only need a subset of these calls. See also Help Session 1 on the course web page.
For File operations:
fopen(), fgets(), fclose(), feof(), fscanf(),fprintf(), fputs()
Note – you can use command line redirection to simplify your file input and output.
For String operations:
strcmp()/strncmp(), strcpy(), strtok(), sprintf(), strstr(),
strcasecmp()/strncasecmp()… /*case insensitive version of strcmp */
toupper() ….. /* converts a character to uppercase */
isupper() ….. /* checks for an uppercase letter. */
For Memory operations:
malloc()/free(), memcpy()/memncpy(), bzero(), memset().
If your program is written in C++ you will obviously need a different set of system calls for your
program.