CS252 Final Review


Please aswer this final review and return it during the final exam.

1. Complete the procedure runCommand( command, outputBuffer, bufferSize) that executes a command in a different process and stores its output in outputBuffer.  command is the name of the program with no arguments. See how main uses runCommand(). runCommand will return 0 on success or -1 otherwise. Hint: Use a pipe to communicate the parent and the child process running runCommand(). Have the parent read from the pipe and write into the outputBuffer.

int
runCommand( char * command, char * outputBuffer, int maxBufferSize)
{
   












}

int
main()
{
    // The output of "ls" will be stored in buffer
    char buffer[ 1024 ];

          if ( runCommand( "ls", buffer, 1024 ) < 0 ) {
       perror("runCommand" );
       exit( -1 );
    }

    printf( "ls: %s\n", buffer );

    exit( 0 );
}


2. Add the necessary code to the insert() and removeFirst() functions to make them synchronized.  removeFirst() will have to wait if the list is empty. insert() will have to wait  if there are already 20 elements in the list. Use semaphores. Add also the variables you need.

struct List {
  int val;
  int next;
};

struct List * head = NULL;

// More variables

main()
{

 // DO any initializations here



}

void insert( int val )
{


  List tmp = new List;

  tmp->val = val;

  tmp->next = head;

  head = tmp;

}

Struct List * removeFirst()
{

  List tmp = head;


  head = tmp->next;


  return tmp;

}


3. From lab3, assuming you have a procedure void dispatchHTTP( int slaveSocket) that processes the request and closes slaveSocket, write the loop server code for a) iterative server, b) concurrent server using fork, c) concurrent server creating a thread after each request, and d) pool of threads,  in  the procedures indicated. Each procedure receives as argument the master socket already initialized and ready to be used inside accept. 

void iterativeServer( int masterSocket) {





}
void forkServer( int masterSocket) {







}


void poolOfThreads( int masterSocket) {







}

void createThreadForEachRequest( int masterSocket ) {








}

// Other procedures







4. Implement a R/W lock class.

RWLock.h

class RWLock
{
   
     
    sema_t _semAccess; mutex_t _mutex;
public:
RWLock();
void readLock();
void writeLock();
void readUnlock();
void writeUnlock();
};

RWLock.cpp
















5. What are the four parameters that a computers needs to be able to get connected to the internet and what are they used for?



6. How does a computer know when it can deliver a packet directly and when it has to pass a packet to a router?



7. What does ARP mean and how does it work?



8. What does DNS mean and what it is used for?



9. What does DHCP mean and how does it work?



10. What does UDP mean?



11. What does TCP mean? What are the 6 features of TCP?




12. When should you use TCP and when should you use UDP?




13. What does NAT stand for? Assume that a packet <A, 4563, X, 80> is sent from a host behind a NAT box to a webserver X. Describe the steps for the translation (6 steps) since it goes from the host A, through the NAT box, to X and then back from X to the NAT box to A.









14. Explain why NAT boxes can be used as firewalls to prevent unwanted connections. Also explain why it is not normally possible to run web servers behind a firewall and how this problem can be solved.





15. Write a simple client program "echo-client host port string" that sends a string "string" followed by "\r\n"to "host : port" and then it reads the server's response and prints it to stdout.












16. Write a simple iterative server "echo-server port" that waits for incoming requests in "port" and once it receives a string delimited by "\r\n" it will reply with the same string plus "\r\n" and close the connection.











17. Enumerate 5 of the 12 questions in "Joel's Test".



18. What is XP programming?


19. From XP Programming, mention 4 items from the Planning List, 4 Items from the Coding List, 4 Items from the Designing List, and 4 Items from the testing List.






20. Explain 5 uses of the source control system.





21. Describe the advantages and disadvantages of centralized vs. distributed source control systems.




22. Describe the 4 types of tests, who writes thoses tests in the organization, and when do they run.




23. Explain why it is importan to have a bugtrack system.




24. Explain the difference between Priority and Severity in a bug.




25. Mention 5 cases when you can apply refactoring.





26. What is a Software Pattern, what are the parts of a software pattern? What is the name of the book that introduced software patterns and the authors?





27. Describe the Proxy Pattern and 2 applications.




28. Describe the Command Pattern and two applications.




29. What is the difference between Code Instrumentation Profiling and Statistical Sampling Profiling.






30. Explain why Optimizing should be left until the very end in the software cycle and why you should use an execution profiler before attempting to optimize a program.





31. Assume the following table called "customers":


CompanyName ContactName Address City
Alfreds Futterkiste  Maria Anders  Obere Str. 57  Berlin 
Berglunds snabbköp  Christina Berglund  Berguvsvägen 8  Luleå 
Centro comercial Moctezuma  Francisco Chang  Sierras de Granada 9993  México D.F. 
Ernst Handel  Roland Mendel  Kirchgasse 6  Graz 
FISSA Fabrica Inter. Salchichas S.A.  Diego Roel  C/ Moralzarzal, 86  Madrid 
Galería del gastrónomo  Eduardo Saavedra  Rambla de Cataluña, 23  Barcelona 
Island Trading  Helen Bennett  Garden House Crowther Way  Cowes 
Königlich Essen  Philip Cramer  Maubelstr. 90  Brandenburg 
Laughing Bacchus Wine Cellars  Yoshi Tannamuri  1900 Oak St.  Vancouver 
Magazzini Alimentari Riuniti  Giovanni Rovelli  Via Ludovico il Moro 22  Bergamo 
North/South  Simon Crowther  South House 300 Queensbridge  London 
Paris spécialités  Marie Bertrand  265, boulevard Charonne  Paris 
Rattlesnake Canyon Grocery  Paula Wilson  2817 Milton Dr.  Albuquerque 
Simons bistro  Jytte Petersen  Vinbæltet 34  København 
The Big Cheese  Liz Nixon  89 Jefferson Way Suite 2  Portland 
Vaffeljernet  Palle Ibsen  Smagsløget 45  Århus 
Wolski Zajazd  Zbyszek Piestrzeniewicz  ul. Filtrowa 68  Warszawa 

Write the result of the following queries (You can use a description when the number of rows in the resultin table is larger than 5, otherwise write down the whole resulting table).

a) SELECT *FROM customers

b) SELECT ContactName FROM customers

c) SELECT CompanyName FROM customers WHERE ContactName LIKE Liz%

d) SELECT CompanyName, ContactName FROM customers WHERE City LIKE Portland

e) Write a query to get the companies that are in Spain

f) Write a query to get all the companies that start with R or W