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HTW Berlin
Fachbereich 4
Internationaler Bachelor Studiengang
Internationale Medieninformatik (Bachelor)
Info 2: Informatik II
Summer Term 2023
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Laboratory
0: Dealing with Objects
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This
exercise can be done in larger groups—there should be at least 2 persons
in each group, and a maximum of 4. You will need lots of paper and pens
and some cards—I have a lot available. You can go outside to do this, if
the weather permits.
What to Bring to Lab
Please bring these exercises P1 and P2 printed out or written out with
you to lab. Please have your name on your page.
P1. How do you obtain tickets to go see a movie? Write
down the steps that you take, in order.
P2. If you have tickets and have to cancel, what do
you have to do? Write down the steps, in order.
P3. Read up on the Class-Responsibility-Collaboration
Card method (CRC Cards). This must be read before class, as you
will not be able to do the exercise if you have no idea what this is.
Post-Lab, AKA
What To Turn In
Your
completed assignment, submitted in Moodle as a pdf, should include:
- A description of what you did during the lab,
including a record of what worked and your final result
- The names and roles of your collaborators.
You may write the report together, but each should please turn in
their own copy of the report.
- A record of how long you needed for this lab
and a reflection on what you learned.
Lab assignments are due the night before the
next lab at 22.00. They may, of course, be turned in earlier. You hand
them in by preparing the report in PDF and submitting it to Moodle. If
you want to hand in the physical cards themselves, you can do this
during the next lab.
Assignment
CRC Cards
- We are going to assume that there have been
several meetings with the operators of a cinema who want to have a
system to handle the bookings of seats for their movie screenings. The
operators have described the expected functionality, but we won't be
concerned with how that happens, this is called Requirements Engineering
and will be discussed in the third semester in Informatik 3. Assume that
this is the description written (adapted from Barnes/Kölling):
The cinema booking system should store seat bookings for multiple
theaters. Each theater has seats arranged in rows. There can be a
different number of seats in every row. Customers can reserve seats, and
are given a row number and a seat number. They may request bookings of
several adjoining seats. Each booking is for a particular show (that is,
the screening of a given movie at a certain time). Shows are at an
assigned date, time, and price, and are scheduled in a theater where
they are screened. The system stores the customer's name and telephone
number. The customer is told what the booking will cost when the tickets
are picked up.
The first step is to discover some candidate classes and methods. Use
the Booch method to determine candidate classes and methods, and write
them down.
- Make CRC cards for each of your candidate
classes. Only put down the class names for now.
- The first scenario that we will be doing is a
reservation:
Jane Doe calls the cinema and want to make a reservation for two seats
to watch Tomb Raider at 8 pm. The cinema employee starts using
the booking system to find and reserve a seat.
Jane is indirectly interacting with the booking system, which will
probably be represented by a class such as CinemaBookingSystem. Using
the CRC cards, play through the scenario. How does the system find the
show? As you discover responsibilities and collaborators, write them
down on the cards. Assume there are plenty of free seats. Jane will
choose seats 13 and 14 from row 12. The reservation is now made. How is
this done, exactly? What data is going to have to be stored? Where? If
you feel the need to create a new class, feel free to do so! If you
discover that a class needs to be split in two—make two new cards and
rip up the old one. If two need to be merged, do so. Keep a list of
things you want to keep track of on a separate piece of paper.
- Choose another scenario and play this through.
If you have time, do more! You will submit your final CRC cards and a
description of the process you went through, in complete sentences. Each
member should submit a copy of the group report with their own
reflection on what they learned.
Here are some suggestions for possible scenarios:
1. James already has a booking and needs another two, adjoining seats.
2. Mary wants to book 4 seats together, but there are not 4 adjoining
seats in one row available.
3. Joseph wants to book, but there are no seats available.
4. Anna has a booking she wants to cancel.
Writeup
Submit your writeup as your post-lab to the
Moodle area by 22.00 the night before your next lab.
Copyright
Prof. Dr. Debora Weber-Wulff
Questions or comments:
<weberwu@htw-berlin.de>
Some rights reserved. CC-BY-NC-SA - Copyright and Warranty