Description
Description
In this part, you are going to write a client program for BBS service. However, in this part, the content of the post will store on the client-side (Amazon S3) instead of the server-side. Take the post function of the BBS service, for example. The server in this part only stores the metadata of posts (e.g., post id, post title, author and date.) except for the content of the post. That is to say, each client has its storage to store the content of their posts, and we use Amazon S3 for the storage service. Besides, you are also going to implement new features such as a simple mail service.
System Architecture
The server here only stores user information, boards and some metadata of posts. (e.g., post id, post title, etc). The real content of the post will store on the client-side (Amazon S3). Each bucket of Amazon S3 represents the storage of each client. So, each client can store the content of its posts in its bucket, and this bucket is also an incoming mailbox for the mail service of this client. Note that only your client program can get access to Amazon S3 using Amazon S3 API.
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 some commands that your client program will interact with Amazon S3. These commands are described as follows:
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Command format |
Description |
Result |
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register <username> <email> <password> |
If successful execution, your client |
Success |
Register successfully. |
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program will create a new bucket in |
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Amazon S3 for this new user, and your |
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Fail |
Username is already used. |
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server program will store the bucket |
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name of this new user so that the user |
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will be able to log in with its bucket in the |
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future. |
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If failed, only print the error message. |
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login <username> <password> |
If successful execution, the user will log |
Success |
Welcome, <username>. |
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in with its Amazon S3 bucket, so that it |
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can manipulate (e.g., upload posts, |
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Fail (1) |
Please logout first. |
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delete posts, etc) its bucket in the future. |
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If failed, only print the error message. |
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Fail (2) |
Login failed. |
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create-post <board-name> –title <title> — |
If successful execution, the user (client) |
Success |
Create post successfully. |
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content <content> |
will upload the content of this post to |
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(command is in the same line ) |
its S3 bucket using Amazon S3 API, |
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Fail (1) |
Board does not exist. |
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and the server will keep the metadata of |
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this post. |
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Fail (2) |
Please login first. |
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If failed, only print the error message. |
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read <post-id> |
Show the post whose ID is <post-id>. |
Success |
Author |
:<Author1> |
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Title |
:<Title1> |
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If successful execution, the client will |
Date |
:<Date1> |
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— |
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get the content of this post from the |
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<content> |
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post owner’s bucket using Amazon S3 |
— |
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API and print the result. |
<User1>:<Comment1> |
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Fail |
Post does not exist. |
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If failed, only print the error message. |
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delete-post <post-id> |
Delete the post whose ID is <post-id>. |
Success |
Delete successfully. |
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If successful execution, the user (client) |
Fail (1) |
Please login first. |
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will delete this post from its bucket, |
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Fail (2) |
Post does not exist. |
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and the server will delete the metadata |
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of this post. |
Fail (3) |
Not the post owner. |
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If failed, only print the error message. |
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update-post <post-id> –title/content <new> |
Update the post whose ID is <post-id>. |
Success |
Update successfully. |
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If a successful update on the title, the |
Fail (1) |
Please login first. |
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server will update the title of this post. |
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Fail (2) |
Post does not exist. |
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If a successful update on the content, the |
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user (client) will update the content of |
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Fail (3) |
Not the post owner. |
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this post in Amazon S3 using Amazon |
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S3 API. |
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If failed, only print the error message. |
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comment <post-id> <comment> |
Add a comment < comment > to the post |
Success |
Comment successfully. |
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whose ID is <post-id>. |
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Fail (1) |
Please login first. |
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If successful execution, the user (client) |
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Fail (2) |
Post does not exist. |
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will append the comment to the content |
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of this post in the post owner’s bucket. |
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That is to say, the comment stores in the |
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post owner’s bucket. |
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If failed, only print the error message. |
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Also, there are some new commands you have to implement for simple mail service. These commands are described as follows:
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Command format |
Description |
Result |
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mail-to <username> –subject <subject> |
Send a mail whose subject is <subject> |
Success |
Sent successfully. |
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–content <content> |
and content is <content> to user |
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(command is in the same line ) |
<username>. |
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Use –subject and –content to separate |
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Fail (1) |
Please login first. |
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subject and content. |
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<subject> has the same format as <title> |
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of the post. |
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<content> has the same format as |
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<content> of the post. |
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If successful execution, the user (client) |
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will create an object with <content> in |
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user <username>’s bucket using |
Fail (2) |
<username> does not exist. |
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Amazon S3 API. |
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Failed execution: |
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Fail (1): No user logged in. |
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Fail (2): User <username> doesn’t exist. |
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list-mail |
List all incoming mails of the current |
Success |
ID |
Subject From |
Date |
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logged in user. |
1 |
<Subject1><From_user1> <Date1> |
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2 |
<Subject2><From_user2> <Date2> |
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Success: |
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Fail (1) |
Please login first. |
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Note that each user has its mail id |
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sequence numbers. It should start at |
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1. |
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<Subject1> represents the subject of this |
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mail. |
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<From_user1> represents that this mail |
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is sent by user <From_user1>. |
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<Date1> represents the sent date of this |
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mail. |
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There is a \t between each column. |
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Failed execution: |
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Fail (1): No user logged in. |
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retr-mail <mail#> |
Retrieve the content of the mail <mail#> |
Success |
Subject |
:<Subject1> |
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From |
:<From_user1> |
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Date |
:<Date1> |
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If successful execution, the user (client) |
— |
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will get the content of the mail from its |
<content> |
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Fail (1) |
Please login first. |
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bucket using Amazon S3 API and print |
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the result. |
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<Subject1> represents the subject of this |
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mail. |
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Fail (2) |
No such mail. |
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<From_user1> represents that this mail |
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is sent by user <From_user1>. |
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<Date1> represents the sent date of this |
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mail. |
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There is a \t before ‘:’. |
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Failed execution: |
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Fail (1): No user logged in. |
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Fail (2): Mail <mail#> is not in your |
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mailbox. |
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delete-mail <mail#> |
Delete mail <mail#> from your mailbox. |
Success |
Mail deleted. |
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If successful execution, the user (client) |
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Fail (1) |
Please login first. |
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will delete the content of the mail from |
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its bucket using Amazon S3 API. |
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Failed execution: |
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Fail (1): No user logged in. |
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Fail (2) |
No such mail. |
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Fail (2): Mail <mail#> is not in your |
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mailbox. |
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Scenario
Run your server first, and run your client program to connect to your server. If the line only shows “% “, that means we type <Enter> in our client program. It is just for the height alignment of two columns here. You can ignore that. The sample outputs of the client program are listed as follows:
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Terminal output |
Description and Amazon S3 Console State |
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Start with nothing in your Amazon S3. |
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bash$ ./client 127.0.0.1 7890 |
Create a bucket for user Brad. You can name the bucket name |
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******************************** |
of each user by yourself, but there are some limitations of the |
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** Welcome to the BBS server. ** |
bucket name. Please refer to the Note part. |
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******************************** |
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% register Brad bb@cs.nctu.edu.tw 12345 |
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Register successfully. |
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% |
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% register Brad bb@cs.nctu.edu.tw 12345 |
Just print the error message. Nothing changes in Amazon S3. |
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Username is already used. |
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% register V v@cs.nctu.edu.tw bt21 |
Create a bucket for user V. |
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Register successfully. |
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% |
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% |
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% |
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% |
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% login Brad 12345 |
The client program will log in with Brad’s bucket. |
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Welcome, Brad. |
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% whoami |
Nothing changes in Amazon S3. |
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Brad |
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% create-board NP_HW |
Nothing changes in Amazon S3. |
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Create board successfully. |
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% create-board NP_HW |
Nothing changes in Amazon S3. |
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Board already exist. |
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% list-board |
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Index |
Name |
Moderator |
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1 |
NP_HW |
Brad |
Nothing changes in Amazon S3. |
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% |
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% |
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% list-board ##HW |
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Index Name |
Moderator |
Nothing changes in Amazon S3. |
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1 |
NP_HW Brad |
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% create-post NP_HW –title NP_HW3 –content Err…<br>Ha! |
Create an object to store the content of this post in Brad’s |
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Create post successfully. |
bucket. By the way, you can name the object by yourself, but |
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% |
there are some restrictions for object naming. Please refer to |
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% |
the Note part. |
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% |
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% |
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% |
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% |
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% |
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% |
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% |
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% create-post NCTU –title NP_HW3 –content Uh… |
Nothing changes in Amazon S3. |
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Board does not exist. |
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% create-post NP_HW –title NP_HW4 –content Wow… |
Create a new post. |
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Create post successfully. |
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% |
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% |
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% |
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% |
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% |
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% |
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% |
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% |
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% list-post NP |
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Board does not exist. |
Nothing changes in Amazon S3. |
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% |
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% |
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% list-post NP_HW |
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ID Title |
Author |
Date |
Nothing changes in Amazon S3. |
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1 |
NP_HW3 |
Brad |
04/14 |
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2 NP_HW4 Brad |
04/14 |
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% list-post NP_HW ##HW3 |
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ID |
Title |
Author |
Date |
Nothing changes in Amazon S3. |
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1 |
NP_HW3 |
Brad |
04/14 |
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% read 888 |
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Post does not exist. |
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% |
Nothing changes in Amazon S3. |
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% |
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% |
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% read 1 |
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Author |
:Brad |
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Title |
:NP_HW3 |
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Date |
:2020-04-14 |
Get the content of post 1 from the post owner’s bucket. |
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— |
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Err… |
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Ha! |
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— |
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% update-post 888 –title NP HW_4 |
Nothing changes in Amazon S3. |
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Post does not exist. |
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% update-post 1 –title NP HW_4 |
The state of Amazon S3 may be unchanged. It depends on your |
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Update successfully. |
design. But for my design, I changed the object key of that post. |
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% |
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% |
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% |
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% |
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% |
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% |
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% |
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% |
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% |
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% |
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% read 1 |
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Author |
:Brad |
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Title |
:NP HW_4 |
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Date |
:2020-04-14 |
Get the content of post 1 from the post owner’s bucket. |
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— |
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Err… |
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Ha! |
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— |
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% update-post 1 –content Yeah! |
Update the content of this post in Amazon S3. |
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Update successfully. |
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% read 1 |
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Author |
:Brad |
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Title |
:NP HW_4 |
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Date |
:2020-04-14 |
Get the content of post 1 from the post owner’s bucket. |
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— |
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Yeah! |
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— |
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% logout |
Nothing changes in Amazon S3. |
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Bye, Brad. |
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% whoami |
Nothing changes in Amazon S3. |
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Please login first. |
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% logout |
Nothing changes in Amazon S3. |
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Please login first. |
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% login V bt21 |
The client program will login with V’s bucket. |
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Welcome, V. |
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% create-post NP_HW –title Hello –content I am<br><br>V. |
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Create post successfully. |
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% |
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% |
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% |
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% |
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% |
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% |
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% |
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% update-post 1 –content Ha!<br>ha! |
Nothing changes in Amazon S3. |
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Not the post owner. |
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% delete-post 1 |
Nothing changes in Amazon S3. |
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Not the post owner. |
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% comment 888 Ha ha! |
Nothing changes in Amazon S3. |
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Post does not exist. |
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% comment 1 Ha ha! |
The client program will append the comment to the |
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Comment successfully. |
corresponding post object (e.g., NP_HW_4- |
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% |
1586850747968524907 object in Brad’s bucket) in Amazon S3. |
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% read 1 |
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Author |
:Brad |
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Title |
:NP HW_4 |
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Date |
:2020-04-14 |
Get the content of post 1 from the post owner’s bucket. |
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— |
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Yeah! |
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— |
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V:Ha ha! |
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% mail-to TT –subject Hi TT –content Hi <br> TT! |
Nothing changes in Amazon S3. |
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TT does not exist. |
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% mail-to Brad –subject Hi Brad –content Hi <br> Brad! |
User V creates two email objects in Brad’s bucket. |
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Sent successfully. |
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% mail-to Brad –subject Hey –content Hey <br>Brad! |
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Sent successfully. |
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% |
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% |
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% |
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% |
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% |
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% list-mail |
Nothing changes in Amazon S3. |
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ID |
Subject |
From Date |
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% delete-mail 1 |
Nothing changes in Amazon S3. |
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No such mail. |
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% retr-mail 1 |
Nothing changes in Amazon S3. |
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No such mail. |
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% logout |
Nothing changes in Amazon S3. |
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Bye, V. |
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% login Brad 12345 |
The client program will login with Brad’s bucket. |
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Welcome, Brad. |
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% list-mail |
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ID |
Subject |
From Date |
Nothing changes in Amazon S3. |
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1 |
Hi Brad |
V |
04/14 |
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2 |
Hey |
V |
04/14 |
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% retr-mail 1 |
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Subject |
:Hi Brad |
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From |
:V |
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Date |
:2020-04-14 |
Get the content of the mail from his bucket. |
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— |
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Hi |
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Brad! |
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% mail-to V –subject Hi V –content WoW V! |
User Brad creates a mail object in V’s bucket. |
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Sent successfully. |
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% |
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% |
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% |
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% |
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% |
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% |
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% |
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% logout |
Nothing changes in Amazon S3. |
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Bye, Brad. |
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% login V bt21 |
The client program will login with V’s bucket. |
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Welcome, V. |
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% list-mail |
Nothing changes in Amazon S3. But note that user V has its |
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ID Subject From |
Date |
mail id sequence number. It starts at 1. |
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1 |
Hi V |
Brad |
04/14 |
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% logout |
Nothing changes in Amazon S3. |
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Bye, V. |
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% login Brad 12345 |
The client program will login with Brad’s bucket. |
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Welcome, Brad. |
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% list-mail |
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ID Subject |
From |
Date |
Nothing changes in Amazon S3. |
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1 |
Hi Brad |
V |
04/14 |
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2 |
Hey |
V |
04/14 |
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% delete-mail 1 |
User Brad deletes the object corresponding to his mail 1 from |
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Mail deleted. |
his bucket. |
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% |
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% |
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% |
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% |
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% |
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% |
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% |
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% |
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% |
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% list-mail |
Nothing changes in Amazon S3. But note that ID of the mail with |
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ID Subject From |
Date |
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the subject “Hey” is 1. |
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1 |
Hey |
V |
04/14 |
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% logout |
Nothing changes in Amazon S3. |
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Bye, Brad. |
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% exit |
Nothing changes in Amazon S3. |
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Note
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About bucket naming:
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Bucket names must be unique across all existing bucket names in Amazon S3.
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Bucket names must be at least 3 and no more than 63 characters long.
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Bucket names must not contain uppercase characters or underscores.
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Bucket names must start with a lowercase letter or number.
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About object key name:
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Unique identifier within a bucket. If you upload the same key name object without versioning-enabled, it will overwrite the original one.
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The following character sets are generally safe for use in key names.
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For more details about buckets and objects, you can refer to reference [5][6]
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About AWS API access key:
If you want to use AWS SDK to make Amazon S3 API calls, you have to provide your AWS credential first. How to set up authentication credential:
Create a credential file at ~/.aws/credentials. The content of this file is described as follows:
[default]
aws_access_key_id=<your access key>
aws_secret_access_key=<your secret access key> aws_session_token=<your session token>
You can get these key from your AWS Educate account. Log in your account and go to Intro. to Network Programming classroom. Then, you will see the following page.
Click Account Details
Click Show and copy those keys into ~/.aws/credentials
The credential we use here is temporary, so you have to copy and paste again when the credential expiration.
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About C++ AWS SDK:
To use the AWS SDK for C++, you need:
Visual Studio 2015 or later
or GNU Compiler Collection (GCC) 4.9 or later or Clang 3.3 or later
A minimum of 4 GB of RAM
So, if you currently use Amazon EC2 with instance type of t2.micro, please change to at least t2.medium. Moreover, please backup all your environment when you are running out of classroom credits. We suggest you write a script to set up your environment. It will save a lot of time.
How to change instance type:
Right-click your original instance -> Instance Settings -> Change Instance Type
Grade (100%)
For those commands that interact with Amazon S3, we will check your Amazon S3 console. If the state of your Amazon S3 is wrong, we will deduct some scores of that command.
register command – (8%) login command – (8%)
create-post command – (8%) read command – (8%)
delete-post command – (8%) update-post command – (8%) comment command – (8%)
mail-to command – (8%) list-mail command – (8%) retr-mail command – (8%)
delete-mail command – (8%) list-post command – (5%)
logout command – (2%) exit command – (2%)
whoami command – (1%)
create-board command – (1%) list-board command – (1%)
Submission
Please upload a zip file called “hw3_{$student_id}.zip” (e.g., hw3_0856020.zip) that includes your source code. It must include at least your server source code and client source code. Submission that doesn’t follow the rule will get 20% punishment on the grade.
You will get 0 points on this project for plagiarism. Please don’t copy-paste other students’ code!
Reference
6.
7.
8.
9.
10.
