1. Introduction
In this part, you are going to implement the subscription features for the BBS service. The event will be raised whenever the client creates a new post that title contains the keyword subscribed by any other client.
2. Example Architecture using Apache Kafka
The middleware server will get a message/record from the producer when there has a new post and also notify the client(s) who have subscribed to the specified topic.
A. BBS server is a producer, and each client is a consumer
B. Each client act as both a producer and a consumer
3. Requirements
The service can serve at least 10 clients. Your server and client program must be able to handle all commands in the previous part (output results must be the same as the previous part). For some commands such as whoami, exit, logout, create-board, list-board ##<key> and list-post <board- name> ##<key>, your client program only sends the command to the server and gets the corresponding result from the server. However, there are new commands that your client program will subscribe to the new post. These commands are described as follows:
Command format
subscribe –board <board-name> –keyword <keyword>
(command and arguments are in the same line)
Description
Subscribe the board with a keyword, notify the client whenever the event be raised.
Note [1]: Can subscribe the same board multiple times with different keywords. Notify user once someone creates a new post with a specified board and the title contains one of the keywords
Note [2]: Subscribe objective (board)
can be nonexistent
Subscribe the author with a keyword, notify the client whenever the event be raised.
Both notes [1] and [2] are same as the previous one (change objective to author) ↑
Unsubscribe the board from the server (or middleware server) and remove all the keywords associated with a specified board.
Unsubscribe the author from the server (or middleware server) and remove all the keywords associated with a specified author.
List the information about the subscribed board(s) and author(s).
Result
Please login first
Already subscribed
same as the previous one same as the previous one
same as the previous one
Unsubscribe successfully
Please login first
You haven’t subscribed <board-name> Unsubscribe successfully
Please login first
You haven’t subscribed <author-name>
List all the subscribed info Please login first
|
Success |
Subscribe successfully (The notify message should at least include board, title, and author) |
|
Fail (2) |
[Invalid option] usage: subscribe –board <board- name> –keyword <keyword> |
subscribe –author <author-name> –keyword <keyword>
(command and arguments are in the same line)
unsubscribe –board <board-name>
unsubscribe –author <author-name>
list-sub
Fail (1)
Fail (3)
Success Fail (1)
Fail (3) Success
Fail (1) Fail (2)
Success
Fail (1) Fail (2)
Success Fail (1)
|
Fail (2) |
[Invalid option] usage: subscribe –author <author- name> –keyword <keyword> |
4. Scenario
Run your server first, and run your client program to connect to your server. The sample outputs of the
client program are listed as follows:
Client 1
Client 2
Client 3
bash$ ./client 127.0.0.1 7777
******************************** ** Welcome to the BBS server. ** ******************************** % register Paul [email protected] 12345
Register successfully.
bash$ ./client 127.0.0.1 7777
******************************** ** Welcome to the BBS server. ** ******************************** % register Brad [email protected] 12345
Register successfully.
bash$ ./client 127.0.0.1 7777
******************************** ** Welcome to the BBS server. ** ******************************** % register Gary [email protected] 12345
Register successfully.
% login Paul 12345
% login Brad 12345
login Gary 12345
%
Welcome, Paul. Welcome, Brad. Welcome, Gary.
% subscribe –board –keyword Project Subscribe successfully
HW4_Board
% subscribe –author Jason –keyword hw4 Subscribe successfully
% create-board HW4_Board
Create board successfully.
% subscribe –board –keyword Project
Already subscribed
% subscribe –author Bryant –keyword exam
Subscribe successfully
HW4_Board
% subscribe –author Paul –keyword HW Subscribe successfully
% subscribe –author Paul –keyword post Subscribe successfully
% unsubscribe –author Brad You haven’t subscribed Brad
% create-post HW4_Board
–title About Project –content HW4… Create post successfully.
% *[HW4_Board] About Project – by Paul* % list-board ##HW
Index Name Moderator 1 HW4_Board Paul
% create-post HW4_Board
–title About HW and Exam –content blablabla
Create post successfully.
% unsubscribe –author Bryant Unsubscribe successfully
% list-sub
Board: HW4_Board: Project
% *[HW4_Board] About HW and Exam – by Paul*
% list-sub
Author: Jason: hw4; Paul: HW, post
5. Notes
1. About implementation:
- There is no limitation on your implementation. You can choose whatever which framework, library, or even implement the logic by yourself, as long as it can achieve the goal of spec.
- The output message should show the information at least greater or equal to mentioned in the requirements. In addition, it not restricted in any format.
3. About Kafka clients: • C/C++
• https://github.com/edenhill/librdkafka
- Python
- Node.js
