Course Project: Notification$-$Based Inter$-$Process Communication

Project description

In this project, you are required to implement a new IPC method called Notification$-$Based IPC $($NIPC$).$ A NIPC instance is a system resource identified by a unique key. Any process that has the key may access the NIPC instance to send$/$receive messages. The procedure to use a NIPC instance is as follows:

A process opens a NIPC instance using its key.

A process subscribes under a specific type $)>(0$ to the opened NIPC instance to receive messages

A process may send messages to an opened NIPC instance using any of the following:

Broadcast: message is sent to all subscribed processes.

Multicast: message is sent to all subscribed processes of certain type.

Unicast: message is sent to a specific subscribed processes.

When a message is sent to the NIPC instance, all intended subscribers are notified. The notified process then have the choice of reading the message or ignoring it$.$

Implementation details

You are required to implement the following functions and submit a library named nipc. $h($along with its $.$ c file$).$ Make sure you perform all necessary testing before submitting the code.

int nipc$\_$create$($key$\_$t $\_$key$)$;

Description : This function creates a NIPC instance that has a key $\_$key. If a NIPC instance with the same key exists, the function fails.

Return value : $0$ on success, $-1$ on failures.

Errors : On failure, errno is set to an appropriate error value. You may define any errors you may need.

int nipc$\_$get $($key$\_$t$\_$ key$)$

Description : This function opens a NIPC instance whose key is $\_$key.

Return value : If the instance exists, it returns a unique positive non$-$zero integer to identify the instance within the process. Otherwise, it returns $-1.$

Errors : On failure, errno is set to an appropriate error value. You may define any errors you may need.

int nipc$\_$subscribe$($int id$,$ long type, void $($handler$*)($struct nipc$\_$message$*))$;

Description : This function subscribes the calling process to the opened NIPC instance identified by id under the specified type "type". The function handler is invoked upon any notification from the NIPC instance.

$1$

Return value : The function returns $0$ on success, and $-1$ otherwise.

Errors : On failure, errno is set to an appropriate error value. You may define any errors you may need.

$4.$ int nipc$\_$send$($int id$,$ struct nipc$\_$message msg$,$ long type$)$;

Description : This function sends the message msg to the NIPC instance identified by id$.$ If type $=0,$ the message is treated as a broadcast. If type $>0,$ the message is treated as a unicast and type is the PID of the receiver. If type the message is treated as a multicast to all receivers subscribed to type $|$type$|.$ The function sends notifications and delivers the message to the intended receivers.