core-extra/docs/tutorials/tutorial2.md

# Tutorial 2 - Wireless Network

## Overview

This tutorial will cover the use of a 3 node scenario in CORE. Then
running a chat server on one node and a chat client on the other. The client will
send a simple message and the server will log receipt of the message.

## Files

Below is the list of files used for this tutorial.

* scenario.xml - 3 node CORE xml scenario file  (wireless)
* scenario.py - 3 node CORE gRPC python script (wireless)

## Running with the XML Scenario File

This section will cover running this sample tutorial using the
XML scenario file, leveraging an NS2 mobility file.

* Make sure the **core-daemon** is running a terminal
   ```shell
   sudop core-daemon
   ```
* In another terminal run the GUI
   ```shell
   core-gui
   ```
* In the GUI menu bar select **File->Open...**
* Navigate to and select this tutorials **scenario.xml** file
* You can now click play to start the session
   <p align="center">
     <img src="/static/tutorial2/wireless.png" width="75%">
   </p>
* Note that OSPF routing protocol is included in the scenario to provide routes to other nodes, as they are discovered
* Double click node **n4** to open a terminal and ping node **n2**
   ```shell
   ping  -c 2 10.0.0.2
   PING 10.0.0.2 (10.0.0.2) 56(84) bytes of data.
   64 bytes from 10.0.0.2: icmp_seq=1 ttl=63 time=20.2 ms
   64 bytes from 10.0.0.2: icmp_seq=2 ttl=63 time=20.2 ms

   --- 10.0.0.2 ping statistics ---
   2 packets transmitted, 2 received, 0% packet loss, time 1000ms
   rtt min/avg/max/mdev = 20.168/20.173/20.178/0.005 ms
   ```

### Configuring Delay

* Right click on the **wlan1** node and select **WLAN Config**, then set delay to 500000
   <p align="center">
     <img src="/static/tutorial2/wireless-config-delay.png" width="90%">
   </p>
* Using the open terminal for node **n4**, ping **n2** again, expect about 2 seconds delay
   ```shell
   ping -c 5 10.0.0.2
   64 bytes from 10.0.0.2: icmp_seq=1 ttl=63 time=2001 ms
   64 bytes from 10.0.0.2: icmp_seq=2 ttl=63 time=2000 ms
   64 bytes from 10.0.0.2: icmp_seq=3 ttl=63 time=2000 ms
   64 bytes from 10.0.0.2: icmp_seq=4 ttl=63 time=2000 ms
   64 bytes from 10.0.0.2: icmp_seq=5 ttl=63 time=2000 ms

   --- 10.0.0.2 ping statistics ---
   5 packets transmitted, 5 received, 0% packet loss, time 4024ms
   rtt min/avg/max/mdev = 2000.176/2000.438/2001.166/0.376 ms, pipe 2
   ```

### Configure Loss

* Right click on the **wlan1** node and select **WLAN Config**, set delay back to 5000 and loss to 10
   <p align="center">
     <img src="/static/tutorial2/wireless-configuration.png" width="90%">
   </p>
* Using the open terminal for node **n4**, ping **n2** again, expect to notice considerable loss
    ```shell
    ping  -c 10 10.0.0.2
    PING 10.0.0.2 (10.0.0.2) 56(84) bytes of data.
    64 bytes from 10.0.0.2: icmp_seq=1 ttl=63 time=20.4 ms
    64 bytes from 10.0.0.2: icmp_seq=2 ttl=63 time=20.5 ms
    64 bytes from 10.0.0.2: icmp_seq=3 ttl=63 time=20.2 ms
    64 bytes from 10.0.0.2: icmp_seq=4 ttl=63 time=20.8 ms
    64 bytes from 10.0.0.2: icmp_seq=5 ttl=63 time=21.9 ms
    64 bytes from 10.0.0.2: icmp_seq=8 ttl=63 time=22.7 ms
    64 bytes from 10.0.0.2: icmp_seq=9 ttl=63 time=22.4 ms
    64 bytes from 10.0.0.2: icmp_seq=10 ttl=63 time=20.3 ms

    --- 10.0.0.2 ping statistics ---
    10 packets transmitted, 8 received, 20% packet loss, time 9064ms
    rtt min/avg/max/mdev = 20.188/21.143/22.717/0.967 ms
    ```
* Make sure to set loss back to 0 when done

## Running with the gRPC Python Script

This section will cover running this sample tutorial using the
gRPC python script and providing mobility over the gRPC interface.

* Make sure the **core-daemon** is running a terminal
   ```shell
   sudop core-daemon
   ```
* In another terminal run the GUI
   ```shell
   core-gui
   ```
* From another terminal run the **scenario.py** script
   ```shell
   /opt/core/venv/bin/python scenario.py
   ```
* In the GUI dialog box select the session and click connect
* You will now have joined the already running scenario

<p align="center">
  <img src="/static/tutorial2/wireless.png" width="90%">
</p>

## Running Software

We will now leverage the installed Chat App software to stand up a server and client
within the nodes of our scenario. You can use the bases of the running scenario from
either **scenario.xml** or the **scenario.py** gRPC script.

* In the GUI double click on node **n4**, this will bring up a terminal for this node
* In the **n4** terminal, run the server
   ```shell
   export PATH=$PATH:/usr/local/bin
   chatapp-server
   ```
* In the GUI double click on node **n2**, this will bring up a terminal for this node
* In the **n2** terminal, run the client
   ```shell
   export PATH=$PATH:/usr/local/bin
   chatapp-client -a 10.0.0.4
   ```
* This will result in **n2** connecting to the server
* In the **n2** terminal, type a message at the client prompt
   ```shell
   >>hello world
   ```
* Observe that text typed at client then appears in the terminal of **n4**
   ```shell
   chat server listening on: :9001
   [server] 10.0.0.2:53684 joining
   [10.0.0.2:53684] hello world
   ```