Distributed Systems
16-17.1.2007

LH 1  Tanenbaum Ch 1 or CoDoKi Ch 1,2


1. You can create a distributed application by, for example,
   partitioning
   the data (and storing each partition on a different server) or
   replicating the data (and storing each replicate on a different
   server). Both solutions have their advantages and disadvantages. What
   kinds? The aspects to be considered are availability, reliability
   (what is "reliability"?), performance, and scalability .
   Use the internet directory system DNS as an example.
   The baseline in the evaluation is a traditional centralized system.


2. Give an example of each transparency type. Use as examples
   a) a distributed file system
   b) printing service (a group of printers)
   which are intended for mobile-user applications.
   Why is it not always a good idea to implement transparency?


Essay assignment 1

Write a "learning diary" about the Chapter 1 of the lectures. The basic
material can be found in the textbooks of Tanenbaum, van Steen and 
Coulouris, Dollimore, Kindberg; the lecture slides you can consider
as the list of contents. 
Length: about 2-4 pages (notice: essential is quality, not quantity).

Essential issues (this time):
1. What were the essential contents of the treatment?
   Organize your text using the typical "abstract" organization 
   (environment, problem/goal, solution principles, evaluation).
   What was a novice student expected to learn?

2. What did you personally learn?
   What was new/surprising/interesting/useful/etc for you?

3a. What intrigueing questions arouse / remained unanswered?
    (For an itroductory piece, there should be plenty of these
    remaining. Make a list of things you intend to learn later!)

3b. Using the textbook, enhance the table 1-24 of Tanenbaum to
    cover more systems ranging from multiprocessor architectures
    to enterprise computing systems. For additional rows, 
    ask yourself for example the following questions:
    - in the system, is it fundamental to have a shared clock?
    - is a shared time essential? how accurate is should be?
    - is there a shared memory? where? how is it used?
    - how fast is the communication channel? how errorprone?
    - are all decisions local? distributed?
    Can you draw distinction between systems within the scope
    of the course and outside of the scope?

The essay should be returned by e-mail to 
Lea.Kutvonen@cs.helsinki.fi, mika.karlstedt@cs.helsinki.fi 
as an attached file (preferably in pdf format, with the name 
[last name].[format type]) at the latest on 22.1. at 8 o'clock .