I declare that this assignment is my own work and that all material previously written or published in any source by any other person has been duly acknowledged in the assignment. I have not submitted this work, or a significant part thereof, previously as part of any academic program. In submitting this assignment I give permission to copy it for assessment purposes only.
Submitted by: George Antonious (3364768)
Assuming JDK 1.8 is installed on the host machine, both parts can be built by doing:
makeTo launch the server do (you can pass in poems.txt to the server):
make runPodServer POEMS_FILE=[path_to_poems]The poems file should contain all the poems seperated by a === sequence. Within a poem the title and content should be sperated using a --- sequence. The following is an example of a properly constructed poems file:
Title of the first Poem
---
Content
of the first Poem.
===
Title of the second Poem
---
Content of the second Poem.
===
To start a session with the server do:
telnet localhost 1822The message format is discussed in the design section below but to mark the end of a message add an empty line followed by a line with a period on it followed by a newline character. This is an example of a telnet sessions with the PoD server.
telnet: Trying ::1...
telnet: Connected to localhost.
telnet: Escape character is '^]'.
server: Welcome to the Poem of The Day Server
server: Select one of the following poems:
server: 1. The Programmers Love by The Internet
server: 2. Christmas Eve by Ella Higginson
server: 3. Paris by Willa Cather
server:
server: .
client: 1
client:
client: .
server: Title: The Programmers Love by The Internet
server: ----------------
server: Roses are Red,
server: Violets are Blue.
server: Unexpected '}',
server: On line 32.
server: ----------------
server: Thanks for reading, visit again soon!
server:
server: .
telnet: Connection closed by foreign host.
I seperated the design for this server into 2 main parts. The protocol and the business logic on top of it (i.e. the PoD server). The protocol is specified and discussed in pod_spec.pdf found in the docs\ directory. The state machine handling client interactions is also specified in that document.
At a high level though, the PoD server is essentially just sending text based messages back and forth between the client. I've opted for a simple protocol where messages are formated as so (the newline characters are shown for visualization purposes):
Body of the message.\n
\n
.\n
Whenever an empty line is followed by a period and another newline character then the message is considered terminated and everything before the empty line is considered the message body. This protocol is encapuslated in the MessageService class where it provides the following methods to send and receive messages:
public Message readNextMessage();
public void writeMessage(Message message);For the usecase of this asssignment telnet is utilized as the client. However, using the MessageService class another client could be implemented in java without worrying about the underlying protocol.
When ever a new client connection is established the client statemachine is activated for that client on a seperate thread. The state machine uses the read and write methods discussed above to communicate with the client. The state machine is discussed in greater detail in pod_spec.pdf.
To test the server telnet was used to interact with it at described above. All the main flows of the state machine were tested and are outlined below.
For this case the server was launched and telnet was used to connect to it. After the server listed the available poems the client requested a valid poem.
Expected Result
The server returns the name and content of the poem.
Actual Result
The server returned the name and content of the poem.
For this case the server was launched and telnet was used to connect to it. After the server listed the available poems the client made an invalid poem request.
Expected Result
The server returns an error message indicating that the client made a bad poem selection.
Actual Result
The server returned an error message indicating that the client made a bad poem selection.
Before the server or client are started the RMI Registry should be launched this can be done by doing:
make runRegistryThe server can be then started by doing:
make runPrimeCalculatorServerThe client can be run by doing:
make runPrimeCalculatorClientThe client will prompt the user for a lower and upper bound then return the highest prime number in between.
The structure of this assignment followed a similar structure to the PI sample provided by oracle (https://docs.oracle.com/javase/tutorial/rmi/overview.html). There is a seperate Task package that provides a TaskExecutor interface and a Task interface. The server class implements the TaskExecutor and accepts Task implementations from remote clients.
For this part a Task implementation was created that computes the largest prime number within a given range and throws and exception if one cannot be found. The algorithm itself is not too complex. It iterates through all the numbers within the range in order and updates the output when a new prime is found.
To determine if a number is prime we first check if it's 2 if so then we just return true. After we check if the number is even, if so we return false right away. Then we iterate through all the odd numbers (except for one) until we reach half of the number we're checking, if the number is not divisible by any of those numbers then we can say it's even.
The actual use case for this part is not too complicated and therefor simple to test. The first major think how ever to test was to ensure that the server and client were properly exporting and binding to the remote interface correctly. After that behavior was confirmed then the prime calculation was checked. The behavior was verified using the test cases below.
After the registry and server were launched the client was started with a range of [-5, 10]. 7 is the largest prime in this range
Expected Result:
7
Actual Result:
7
After the registry and server were launched the client was started with a range of [-5, 1]. There is no prime number in this range.
Expected Result:
part2.client.PrimeCalculatorTask$NoPrimeFoundException: Could not find a prime number within -5 and 1.
Actual Result:
part2.client.PrimeCalculatorTask$NoPrimeFoundException: Could not find a prime number within -5 and 1.