MP1

A simple network simulation implement with application layer and network layer

To Run

There are two simulations in this project.
The first simulation simulates one process sends a message to another process.
The second simulation simulates multiple processes send messages to a single process.

One to one

Open two terminals. In the first terminal, start a TCP server. In this case, it is the process 1.

go run main.go 1

Then in the second terminal, a user (process 2) wants to send message to the process 1.

go run main.go 2

Then you should see a guide look like this in your window:

please send application in this pattern: send 'processNumber' 'YourMessage'

So you follow the instruction:

send 1 hi

A notification should look like this:

Sent 'hi' to 1, system time is Sep 11 16:16:28.681

After a little bit delay, on your first terminal, you should receive a notification as well, indicates the message has been received:

Received 'hi' from 2, system time is Sep 11 16:16:30.687

Multiple to One

It is similar to the one-to-one, except we need three terminals. One represents a server, two represent the clients.

In the first terminal, run following command:

go run main.go 3

In the second terminal, run:

go run main.go 2

send a message:

send 3 thisIs2

You should see something like this:

Sent 'thisIs2' to 3, system time is Sep 12 14:17:33.526

And the server will print:

Received 'thisIs2' from 2, system time is Sep 12 14:17:35.340

In the third terminal, run:

go run main.go 4

send a message:

send 3 thisIs4

You should see something like this:

Sent 'thisIs4' to 3, system time is Sep 12 14:19:16.937

In the server terminal you should see:

Received 'thisIs4' from 4, system time is Sep 12 14:19:19.763

Then the server will shut down.

Structure and Design

application

In /application/message.go, there are two struct:

type Process struct {
	Id   string
	Ip   string
	Port string
}

type Message struct {
	S Process
	R string
	M string
	T string
}

The Process struct contains the basic information of a process, and the Message struct contains four elements: S represent source, R represent receiver, M represent the text being sent, T represent the time sent. \

It mainly simulates the application layer. The GetInfo function takes a process as input, instruct the user to send the message, and then returns a Message struct. The UnicastReceive function simply takes the source Process and Message as input, and print out the time received the message for the server.

network

The /network/clients.go contains UnicastSend function, which takes the destination Process and Message as input, try to send the message to the destination via TCP connection. It is encoded with the support of gob. It also prints out the sent time and information for the client user.

The/network/servers.go contains Server function, which function as a go routine in the main function. It initialize a TCP server, and writes the message it receives to a go channel. The main function can then read the message from the channel and pass it to the UnicastReceive function. We also simulate the network delay in this function.

Sources

• Channels and Go Routines
• Create a TCP and UDP Client and Server using Go
• Go Routines
• MP0 by Jiahong Li and Zheng Zhou
• Net Package
• Random Numbers
• Read Files
• Time Package

Authors

• Gary Ge - initial work