Description
DESCRIPTION:
In this assignment, you will have a chance to gain experience with the Python
programming language. Python is an easy to use, dynamically typed Object Oriented language. It is
syntactically similar to C-style languages like C++, C# and Java, but is somewhat simpler to
understand, at least at the modest level of skill required for this assignment.
Your job will be to develop a small database server. Ordinarily, this would be a significant
undertaking. However, with Python, this will be surprisingly straightforward and requires a
relatively trivial amount of code.
Your DB system will work as follows:
1. You will construct a client/server application. In your case, only one client program will
access the DB, so you do not have to worry about issues like concurrency or thread control.
It’s just a one-to-one form of communication. Python provides a socketserver class in its
standard libraries (and various other network facilities as well). You can use this to get
started if you like, along with the sample code provided in the Python docs (you can use the
9999 port for the DB server).
2. In addition to listening for client requests, the server program must load the database and
provide access to the data. The data base will be loaded from a simple, plain text disk file
called data.txt. In your case, the database will hold customer records. A customer record
will be a tuple with the following format
(name, age, address, phone#)
To record this information on disk, you will store one record per line, and separate each
field with a bar symbol (‘|’). A simple 3 record database might look like this
John|43|123 Apple street|514 428-3452
Katya| 26|49 Queen Mary Road|514 234-7654
Ahmad|91|1888 Pepper Lane|
Note that these values are very simple (first name, street address only, etc.). Also note that
some basic checking must be done when values are read. For example, additional leading or
trailing spaces may be present (e.g., Katya’s age field), and some fields may not have a value
at all (e.g., Ahmad’s phone#). This is okay, as long as the name field is provided. If the name
is missing, the record should be skipped. In any case, you should provide some basic error
checking to make sure that your code doesn’t simply crash in these cases.
For the assignment, you should create a text file with about 20 records. The marker will use
a data set of the same general format for grading purposes. (We do not provide the testing
set to students beforehand but there are no surprises in the test set – it is exactly as
described above)
3. When the server is started, the first thing it will do is load the data set into memory (The
database file should be stored in the same folder as the server application). Each tuple will
be stored in an in-memory data structure. Python provides a dictionary structure for this
purpose. In your case, you must look up customers by name. So if I want to see the
information for customer “John”, for example, this should be a very simple operation.
4. You will also build a trivial client application to access the server. Again, you can use the
sample code on the main python website as a starting point. The idea is that you will send a
request (just a text string) to the server and ask for a specific task to be performed. The
possible requests are as follows:
Python DB Menu
1. Find customer
2. Add customer
3. Delete customer
4. Update customer age
5. Update customer address
6. Update customer phone
7. Print report
8. Exit
Select:
This may look like a lot of options, but each of these is quite trivial. To make it easier to send
commands, you will present a menu type interface. The Select prompt at the bottom will
wait for a number to be entered. When a valid menu option is provided, the client
application will then take the appropriate action as follows:
1. Find customer: Prompt the user for a name and then send the name to the server. The
server will respond to the client either with the full customer record or a “customer not
found” message. Note that this message MUST be sent back to the client which will then
display it. The server itself should never print anything directly since, in theory, it could
be placed on another machine. The menu will then be displayed again so that another
choice can be made.
2. Add customer: The client will prompt the user to enter each of the four fields. These will
be collected and sent to the server and the server will respond with either a “Customer
already exists” message or a confirmation message that the customer has been added.
3. Delete customer: Delete the specified customer. The server will respond with either a
“Customer does not exist” message or a confirmation message.
4. Update options: all update options will prompt for a name, then for the field to be
updated. The server will respond either with a “Customer not found” message or a
confirmation message.
5. Print Report: This will print the contents of the database, sorted by name. Note that the
sorted contents should be sent by the server back to the client and then displayed by the
client app.
The Print Report function is mandatory because it is the primary way for the
grader (and you) to determine if the database server is working correctly. Specifically,
you can display the database before you perform any updates, then check it again later
to make sure everything is working. You can NOT get a passing grade on the assignment
if the Print Report option does not work!
As noted, no 3rd party libraries can be used. So do not download and install some sort of
Python reporting/table function here. You must write the reporting code yourself and
provide basic formatting to ensure that the output is readable.
6. Exit does the obvious thing. It should print a “Good bye” message and simply terminate
the client application. Note that the server process will still be running since it executes
in an infinite loop. If the client is restarted, it should reconnect with the existing server.
If you want to stop the server, you can do so either from the development GUI (e.g.,
Eclipse ‘kill’ button), or from the command line with a ‘kill’ signal.
So that’s the basic idea. If you haven’t used Python before, you will find that it is a very accessible
language with a lot of documentation and supporting materials online. If you like to code, this
assignment should actually be fun.
DELIVERABLES: Your submission will have exactly two source files. Specifically, it will have a file
called server.py and a filed called client.py. Do not include the data.txt file since the
marker must use his/her own test set to ensure that all students are evaluated in the same way.
Do NOT use any additional packages or folders. Doing so can be very problematic for the graders
since they need to be able to run a huge number of programs, without having to deal with
unexpected path/navigation errors. So make sure that your code will simply run from the current
folder.
Once you are ready to submit, combine your two source files into a zip file. The name of the zip file
will consist of “a1” + last name + first name + student ID + “.zip”, using the underscore character “_”
as the separator. For example, if your name is John Smith and your ID is “123456”, then your zip file
would be combined into a file called a1_Smith_John_123456.zip”. The final zip file will be submitted
through the course web site on Moodle. You simply upload the file using the link on the assignment
web page.
Final note: As I have mentioned before, you are free to develop the Python code however you like:
by downloading and setting up a traditional development environment on your own machine (it’s
not hard at all) or by using an online system like repl.it. If you find that the simple online
approach works for you, then you need not do any more than that, as long as you meet the
requirements of the assignment.
Good Luck
