Assumptions

Storage Server

While the storage server is down, we are assuming no modifications such as adding / deleting / updating new files happen on the Storage server. The state remains exactly the same.
The UNIQUE ID assigned to the SS does not change. (In real world the ID can be thought of something unique to a physical storage server like its MAC Address).
The SS_PORT is unique for each storage server. It is defined as a macro and thus needs to be manually changed when creating and running a new storage server.
The S_SSPORT is for ss-ss comunications and is common for all storage servers.
The storage servers need to have different IPs to differentiate them on same network and hence no two storage servers can run on same machine with same IP.
The naming server IP and Port is made known to each storage server by using CLI.

Naming Server

The naming server has two pre-defined ports for back-communication for handling ASYNC write acknowledgements.
During Write request, we assume that no delete or copy requests from any client.
When any storage server comes back online, only the unique ID is matched in the ss_serverlist to check if the storage server had previously been connected.

Client Server

The naming server IP and Port is made known to each client by using CLI.
Each storage server upon starting has access to it's own database in the form of a folder SS_<UNIQUE_ID>. One storage server cannot access other storage server's private folder.
A file and a folder with the same name cannot exist.

Important Macros

In Naming Server

// Error Codes
#define SUCCESS 0
#define FILE_ALREADY_EXISTS 400
#define FILE_NOT_FOUND 404
#define STORAGE_SERVER_NOT_FOUND 505
#define ACCESS_DENIED 999
#define FILE_NOT_CREATED 1001
#define FILE_NOT_DELETED 1000
#define INVALID_PATH 100
#define CLIENT_SERVER_DISCONNECTED 200
#define TIMEOUT 600

#define MAXCLIENTS 100
#define MAXPATHLEN 200
#define MAX_FILES 100
#define MAXFILENAME 100
#define NS_PORT 8080       // Port for connecting clients
#define NS_PORT_SS 8000    // Port for connecting storage servers
#define MAXSSERVER 100
#define ALPHABET_SIZE 256
#define MAXDATASIZE 100
#define CACHE_SIZE 2

```
#define BACK_CHANNEL_PORT 5113 
```

In SS

#define SS_PORT 8005  // Port for client connections
#define S_SSPORT 8010 // for ss-ss comms
#define BACKUP_PORT 8011
#define MAX_BUFFER 1024
#define MAXPATHLEN 200
#define MAXFILENAME 100
#define MAX_FILES 100
#define UNIQUE_ID 100
#define BUFFER_SIZE 1024
#define MAXSSERVER 100
#define MAXDATASIZE 100
#define WRITEBUFFER 4096

In Client

# define MAXDATASIZE 100
# define MAXPATHLEN 200
# define MAXFILENAME 100
#define CMD_READ 1 // Kind 1 request
#define CMD_WRITE 2 // Kind 1 request 
#define CMD_DELETE 3 // Kind 2 request
#define CMD_GET_INFO 4 // Kind 1 request
#define CMD_STREAM 5 // Kind 
#define CMD_CREATE 6 // Kind 
#define CMD_COPY 7 
#define CMD_LIST 8
#define CMD_APPEND 9
#define CMD_WRITE_ASYNC 10

# define EXIT_STATUS 10 
# define CLEAR_STATUS 9
# define KIND_1 1 
# define KIND_2 2 
# define KIND_3 3

User View

Running the NFS

First run name server by going into Naming server directory by using cd command.

Naming server % make
gcc ns.c LRU.c backcommunication.c logging.c clienthandler.c sserverhandler.c trie.c locks.c -lpthread -o ns.o
Naming server % ./ns.o

Then connect all storage server (Ensuring unique values of UNIQUE_ID and SS_PORT) by running the following steps in SS folder.

SS % make
gcc ss.c func.c read_write.c namingserverhandler.c clientserverhandler.c storageserverhandler.c threadhandler.c copy.c -o ss.o -pthread -lm
SS % ./ss.o <naming_server_ip> <naming_server_port_for_ss>

The <naming_server_port_for_ss> is given by NS_PORT_SS in headers.h of Naming server.
Then the clients can connect by running the following steps in Client folder.

Client % make
gcc client.c -o client 
Client % ./client <naming_server_ip> <naming_server_port_for_client>

The <naming_server_port_for_client> is given by NS_PORT in headers.h of SS.

Commands

As soon as the client logs in, it is greeted with a help message that prints all commands available to the user

Commands available:
  READ <path> - Read a file
  WRITE <path> - Write to a file
  WRITEASYNC <path> - Write to a file asynchronously
  DELETE <directory_path> <filename>- Delete a file
  DELETE <directory> - Delete a directory
  GETINFO <path> - Get information about a file or directory
  STREAM <path> - Stream a music file
  CREATE <path> <name> - Create a file
  CREATE <directory_path> <name> - Create a folder
  COPY <source> <dest> - Copy a file
  APPEND <path> - Append to a file
  LIST <path> - List all files in a directory (Press ~ for root)
  HELP - Show this help message
  clear - Clear the screen
  exit - Exit the program
Connected successfully to port : 8000

Here is the list of all the commands the user can use to interact with the NFS.
- READ <path>: Reads the content of the specified file from the storage server. The path is from the root directory however it is not needed to be specified.
  - USAGE
    - For the below file structure.
```
file.txt // in root directory
abc/file.txt
dir1/dir2/file.txt
```
    - The user can access the text files by running below commands.
```
READ file.txt
READ abc/file.txt
READ dir1/dir2/file.txt
```
- WRITE <path>: Writes data to the specified file on the storage server.
  - USAGE
    - For the below file structure.
```
file.txt // in root directory
abc/file.txt
dir1/dir2/file.txt
```
    - The user can write to the text files by running below commands.
```
WRITE file.txt
WRITE abc/file.txt
WRITE dir1/dir2/file.txt
```
    - For writing the content
```
> > hi this is line 1
> this is line 2
> END
```
    - END\n signifies the end of the input.
- WRITEASYNC <path>: Writes data to the specified file asynchronously on the storage server.
  - USAGE
    - For the below file structure.
```
file.txt // in root directory
abc/file.txt
dir1/dir2/file.txt
```
    - The user can write asynchronously to the text files by running below commands.
```
WRITEASYNC file.txt
WRITEASYNC abc/file.txt
WRITEASYNC dir1/dir2/file.txt
```
  - ACKS
    - After a specified timeout or if the content is written to file, an ACK is received by the client along with respective error codes to ensure whether the WRITE was succesful or not.
- DELETE <directory_path> <filename>: Deletes the specified file from the directory on the naming server.
  - USAGE
    - For the below file structure.
```
file.txt
abc/file.txt
dir1/dir2/file.txt
```
    - The user can delete the text files by running below commands.
```
DELETE . file.txt
DELETE abc file.txt
DELETE dir1/dir2 file.txt
```
- DELETE <directory>: Deletes the specified directory from the naming server.
  - USAGE
    - For the below directory structure.
```
abc/
dir1/dir2/
```
    - The user can delete the directories by running below commands.
```
DELETE abc
DELETE dir1/dir2
```
  - DELETE . is a restricted command and user cannot delete the rrot directory by using this command. However they can clear the root directory by indivsuallly removing all file paths and directories in the root directory.
- GETINFO <path>: Retrieves information about the specified file or directory from the storage server.
  - USAGE
    - For the below file structure.
```
file.txt // in root directory
abc/file.txt
dir1/dir2/file.txt
```
    - The user can get information about the text files by running below commands.
```
GETINFO file.txt
GETINFO abc/file.txt
GETINFO dir1/dir2/file.txt
```
  - OUTPUT
```
File Information:
Size: 18 bytes
Permissions: -rw-r--r--
Owner: dheeru
Group: staff
Last Modified: Nov 20 03:03
Number of Links: 1
```
- STREAM <path>: Streams the specified music file from the storage server.
  - USAGE
    - For the below file structure.
```
song.mp3 // in root directory
abc/song.mp3
dir1/dir2/song.mp3
```
    - The user can stream the music files by running below commands.
```
STREAM song.mp3
STREAM abc/song.mp3
STREAM dir1/dir2/song.mp3
```
    - The mpv player spawn a new terminal with the audio/video player with default controls. Closing it returns normal function for the user.
- CREATE <path> <name>: Creates a new file with the specified name at the given path on the naming server.
  - USAGE
    - For the below directory structure.
```
abc/
dir1/dir2/
```
    - The user can create new text files by running below commands.
```
CREATE . newfile.txt // for creating in root directory
CREATE abc newfile.txt
CREATE dir1/dir2 newfile.txt
```
- CREATE <directory_path> <name>: Creates a new folder with the specified name at the given directory path on the naming server.
  - USAGE
    - For the below directory structure.
```
abc/
dir1/dir2/
```
    - The user can create new directories by running below commands.
```
CREATE . xyz // for creating in root directory
CREATE abc newdir
CREATE dir1/dir2 newdir
```
- COPY <source> <dest>: Copies the specified file from the source path to the destination path on the naming server.
  - USAGE
    - For the below file structure.
```
file.txt // in root directory
abc/file2.txt
dir1/dir2/file3.txt
```
    - The user can copy the text files or directories to a destination directory by running below commands.
```
COPY file.txt abc
COPY abc/file2.txt dir1/dir2
COPY dir1/dir2/file3.txt . // for copying to root directory
COPY . abc // for copying root directory to specified directory
```
    - The user can copy only to directories. The code will raise an exception if the dest is not a directory.
- APPEND <path>: Appends data to the specified file on the storage server.
  - USAGE
    - Exactly the same as WRITE
- LIST <path>: Lists all files in the specified directory. Use ~ for the root directory.
  - USAGE
    - For the below directory structure.
```
abc/
dir1/dir2/
```
    - The user can list all files in the directories by running below commands.
```
LIST abc
LIST dir1/dir2
LIST ~
```
- HELP: Displays the help message with all available commands.
- clear: Clears the screen.
- exit: Exits the program.

Name		Name	Last commit message	Last commit date
Latest commit History 3 Commits
Client		Client
Naming server		Naming server
SS		SS
README.md		README.md

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