The answers are in boldface.

1. Place these events in chronological order from earliest to most recent.

   • 1. Work on Unix Begins.
     2. CORBA 1.1 is released.
     3. Java RMI ships.
     4. .NET initiative is announced.
   • 1. Work on Unix Begins.
     2. CORBA 1.1 is released.
     3. Java RMI ships.
     4. .NET initiative is announced.
   • 1. CORBA 1.1 is released.
     2. Work on Unix Begins.
     3. .NET initiative is announced.
     4. Java RMI ships.
   • 1. Work on Unix Begins.
     2. Java RMI ships.
     3. .NET initiative is announced.
     4. CORBA 1.1 is released.
   • 1. Work on Unix Begins.
     2. .NET initiative is announced.
     3. CORBA 1.1 is released.
     4. Java RMI ships.

2. The host-to-network layer, usually populated by the Ethernet, is responsible for

   • Placing and retrieving electronic signals on the transmission medium.
   • Propagating IP packets between networks.
   • Establishing reliable connections between two hosts.
   • Determining how IP packets are to be routed.
   • Moving IP packets between a host and the network at large.

3. Which one of the following choices is not part of the basic IP datagram.

   • Destination port number
   • Datagram length
   • Destination IP address
   • IP version number
   • Header checksum

4. If you want every HTTP connection from the computers in your LAN to first be served by a local cache (if possible) then you want to set up a (pick best):

   • Proxy
   • Network Address Translator
   • Router
   • Gateway
   • Firewall

5. The Domain Name System scales well because

   • It is hierarchical.
   • It is centralized.
   • It has 8 root nodes.
   • It uses TCP/IP
   • It employs high-end machines.

6. Ports are

   • An abstraction used by TCP to facilitate many connections to the same machine.
   • All reserved by an IETF standard.
   • A networking abstraction used only by UNIX machines.
   • A technique for routing IP packets.
   • A feature of UDP packets.

7. A Network Address Translator (NAT) is

   • A service that changes the source IPs of datagrams coming out of a LAN.
   • A service that changes machine names into IP numbers.
   • A router with WAN capabilities.
   • A device that works at the physical layer for serial IP protocols.
   • A distributed address database.

8. A Request For Comments (RFC) is

   • Documents that describe the IETF standards.
   • A formal request for critiques of a hypothetical (i.e., not yet implemented) standard.
   • A document that describes the workings of the Internet.
   • An election protocol for DNS authorities.
   • The first stage in the IETF standards process.

9. An Universal Resource Name (URN) is of the form

   • urn:namespace:resource-name
   • protocol:resource-name
   • scheme:scheme-specific part
   • protocol://hostname:resource-name
   • protocol:namespace/resource-name

10. Place these three languages in chronological order from earliest to most recently developed.

    • SGML, HTML, XML
    • HTML, SGML, XML
    • XML, SGML, HTML
    • SGML, XML, HTML
    • HTML, XML, SGML

11. Cookies enable an HTTP server to maintain state because

    • They allow it to group together all the requests coming from each client.
    • They allow it to identify the user of the browser.
    • They allow the connection to stay open for multiple requests.
    • They are opaque.
    • They allow it to communicate with other servers.

12. The difference between Java byte streams and character streams is that

    • Byte streams read in 8-bit bytes while character streams read in 16-bit characters.
    • Byte streams are capable of reading in data in binary format while character streams read in only plain text.
    • Byte streams are optimized for writing to disk while character streams are used for socket connections.
    • There is no difference.
    • Byte streams use little-endian notation while character streams use bid-endian.

13. The member function used to read bytes from a Java InputStream is called:

    • read
    • write
    • input
    • get
    • getBytes

14. If you wanted two threads to pass data between them but wanted to avoid all the complexities associated with locking a shared variable, you could:

    • Use a PipedReader and PipedWriter
    • Use ThreadGroups
    • Use multiple JVMs
    • Use Sockets
    • It cannot be avoided. We must use synchronize and wait.

15. Buffering a stream is useful

    • When writing small pieces to a file.
    • For checking the parity of the data.
    • For speeding up the rate at which we can send data on a socket.
    • When we want some added security.
    • When running the debugger seems like a good idea.

16. If you wanted to send a large data file over a socket using the CheckedOutputStream you need to:

    • Apply the checksums at fixed intervals.
    • Create a new CheckedOutputStream surrounding the existing socket stream and just send all data on it.
    • One can only send small files with CheckedOutputStream
    • Use a binary socket stream.
    • Make sure that the CheckedOutputStream is using the appropriate encryption cyphers.

17. If you want to send a String from a Java program in a platform-independent fashion you could

    • use writeUTF
    • use toString
    • use DataOutputStream
    • write a function to convert the String to ISO characters.
    • use writeCanonicalForm

18. If you serialize an object (using Java serialization) and send it to someone else over a socket, which one of the following statements is false.

    • The receiver can call methods on that object.
    • The receiver will be able to forward it to someone else.
    • The receiver can write the object to a file.
    • The receiver can check the class of the object.
    • The receiver can try to typecast the object.

19. You start a Java Thread running by

    • Calling its start method.
    • Calling its run method.
    • Calling its main method.
    • Creating it with a new.
    • Calling notify.

20. What are the state in a Java thread's life-cycle?

    • new, runnable, not runnable, dead.
    • running, stopped
    • running, waiting
    • new, runnable, waiting, blocked, yielding
    • runnable, blocked, starting, sleeping

21. You implement two Java threads in your Unix machine. The first one runs a compute-intensive loop, the second one reads from the hard drive, none of them yield. Both of them have the same priority. What will happen if you start them both?

    • The first one will, on average, execute more often.
    • The first one will consume all (or, at least most) of the CPU power.
    • The second one will consume all (or, at least most) of the CPU power.
    • The second one will, on average, execute more often.
    • They will both, on average, execute just as often.

22. Why would you need to implement a thread using the Runnable interface?

    • When the class already inherits from another class.
    • Because it looks more professional.
    • When the run method has already been declared for some other use.
    • Because Java's multiple-inheritance implementation can often make a program very slow.
    • Because there is no other way to implement a thread.

23. If a Java object joe of class Human (which is not a Java thread) calls the wait method, what happens?

    • The method blocks until someone calls joe.notifyAll.
    • The method blocks until someone calls Human.notifyAll.
    • The method blocks until someone calls Human.wait.
    • The method returns immediately since Human is not a thread.
    • The method returns until someone calls notifyAll.

24. The Java URL class is used for

    • Opening a connection to the given URL. The connection understands the underlying protocol.
    • Opening a socket to the given URL.
    • Opening an HTTP connection to the specified URL.
    • Parsing URL strings into their specified parts.
    • Passing objects to sockets via the Serializable interface.

25. Sockets are

    • An abstraction that transcends programming languages.
    • An abstraction dictated by the OSI model.
    • An abstraction developed by Java.
    • One of the seven OSI layers.
    • Only used when a TCP/IP connection is not available.

26. In any communication using sockets it is always true that:

    • One end has to listen on a port until the other someone connects.
    • One end sends information while the other one receives it.
    • One end sends data, then the other end, then the connection is closed.
    • Both ends must be listening for incoming connections.
    • All information is encoded using the best available encryption cyphers.

27. When using sockets, the method setSoLinger is used to

    • Set the number of seconds to wait, after the socket has been closed, before giving up trying to send unsent packets.
    • If set to true then send all packet immediately without waiting for an ACK.
    • Set the amount of time the socket will block waiting for someone to connect.
    • If set to true then send packets every so often in order to keep the connection alive.
    • Set the amount of time to wait for an ACK.

28. In order to establish a UDP connection to another host using Java you need to

    • First create a datagram, then a datagram socket, then send the datagram on the socket.
    • Open a UDP datagram socket to the other side and send data on it.
    • First open a socket to the other side and then use this TCP socket to send datagrams.
    • Simply create a UDP datagram and have it send itself.
    • Determine the UDP protocol used by the other side and then send the appropriate datagrams.

29. Which one of the following is not a reason for the development of distributed object systems (DOS).

    • Sockets are not capable of transmitting the kinds of data required when building a DOS.
    • With a DOS there is no need to define a new protocol each time new functionality is desired.
    • With DOS the user of does not have to worry about data conversion.
    • If one uses a DOS then it is easier to later change the location of the object.
    • DOS make it easier to implement fine-grained security mechanisms.

30. In Distributed Object Systems a skeleton

    • Runs on the object server.
    • Runs on the client.
    • Is an object that pretends to be the real object but actually passes all commands to another machine.
    • Must be implemented, in its entirety, by the programmer.
    • Is the process the user must go thru when invoking a remote object.

31. The reason that when building a distributed object system the client ends up having to also be a server (and viz.) is

    • The value of a parameter could be a local object.
    • The client could send the server a reference to an object running on a third machine.
    • It does not. The object server need not be an object client (and viz.).
    • Because DOS are really P2P systems.
    • The object registry cannot handle objects without skeletons.

32. In general, the first step when building your class for a distributed objects system, is

    • To describe the object's interface using an IDL.
    • To implement the run method on the object.
    • To decide which part of your object is the client and which is the server.
    • To determine if the methods in your class are synchronous or asynchronous.
    • To define a protocol for interacting with the object.

33. Which one of the following is not the responsibility of the object manager in a distributed object system?

    • To compile the object interface into stub and skeleton code.
    • To create new remote objects.
    • To handle the routing of messages to remote objects.
    • To handle the deletion of remote objects.
    • To send back references to remote objects.

34. The function of a naming service in a distributed object system is to:

    • Maintain the mapping between interfaces and servers.
    • Provide a name to every new object.
    • Map between object names and IP addresses.
    • Map between class names and IP addresses.
    • Map between machine name and object name pairs into server addresses.

35. The flow of control in a typical invocation of a distributed object's method goes like

    • client, stub, skeleton, object
    • client, object manager, skeleton, object
    • client, skeleton, stub, object
    • client, skeleton, object
    • client, naming service, object manager, stub, skeleton, object

36. Say you have a reference to a remote object and you send this reference to another machine. What conditions must exist in order for the other machine to be able to invoke methods on this object.

    • The reference must point to the the object server and the other machine must have the class of the stub for that reference.
    • The reference must be a serialized version of the object.
    • The remote machine must have a serialized version of the skeleton for the object and the reference must point to this skeleton.
    • The reference must contain the stub of the object and the other machine must have the class of the skeleton for that reference.
    • It cannot be done.

37. JXTA was designed

    • To enable the implementation of sophisticated P2P application.
    • As the next step in distributed object computing.
    • As a response to .NET.
    • As an extension to the Java Swing library.
    • By a large but finite number of monkeys.

38. An feature of JXTA pipes that sets them apart from sockets is that

    • Pipe endpoints can be moved among peers.
    • Pipes can send encrypted data.
    • Pipes are optimized for peer-to-peer communication.
    • Pipes are longer than sockets.
    • Pipes have higher throughput.

39. Why is it hard in a P2P application (like JXTA) to find a peer that fits a particular description.

    • Because there is not central repository of information.
    • Because peers can only talk to a few other peers.
    • Because pipes are not designed for that type of query.
    • Because P2P applications tend to send too many messages.
    • Because the registry service must be constantly updated.

40. In JXTA a peer group is

    • A virtual entity that speaks the set of peer group protocols.
    • A group of peers with the same set of goals.
    • A group of peers that run on the same machine.
    • A group of peers that run on the same LAN.
    • A metaphor for cooperation.