CS655GENI Mini Project - Web Cache

Fuqing Wang, Jian Ma, Jun Li, Tian Chen

Note: Please check the IP address for each node before configuration. For example, if the IP address for cache node is 10.10.1.1, so you need to replace all 10.10.1.2 with 10.10.1.1 for any involved configuration below.

Here we assume you are familiar with basic Linux commands, and know how to login to GENI nodes using ssh.

1 Configurations

1.1 Proxy (cache) server (Apache Traffic Server 7.1.2)

1. Install ATS (Install from source code is preferred, see here, note that the trafficserver commands & configurations will be under directory /opt/ts/)

   sudo apt-get update && sudo apt-get install trafficserver

2. Fix bug if you install ATS from apt-get (reference)

   sudo mkdir /var/run/trafficserver
   sudo chown -R trafficserver:trafficserver /var/run/trafficserver

3. Create Mapping Rules for HTTP Requests

   sudo vim /etc/trafficserver/remap.config

   Then add a mapping rule (in order to set ATS as a reversed proxy):

   map http://10.10.1.2:8080/ http://10.10.2.2:80/
   

   Note: Please check if the IP address of cache node is 10.10.1.2. If its 10.10.1.1, replace 10.10.1.2 above with 10.10.1.1

4. Configure ATS to accept all request for caching:

   sudo vim /etc/trafficserver/records.config

   Modify the following line (cache all objects no matter what the request header is):

   CONFIG proxy.config.http.cache.required_headers INT 0
   

   Then save and quit vim using :wq.

5. Filter URL for objects that are not to be cached

   sudo vim /etc/trafficserver/cache.config

   Add rule: (this rule means any object from any host with suffix nocache will never be cached by ATS)

   dest_domain=. suffix=nocache action=never-cache
   

6. Then reload configuration and restart ATS:

   sudo traffic_ctl config reload
   sudo traffic_ctl server restart

7. Set link delay

   sudo tc qdisc add dev eth1 root netem delay 10ms

1.2 Server (Apache2 Web Server 2.4.29)

1. Install Apache2

   sudo apt-get update && sudo apt-get install apache2

2. [Optional] Configure static file path in VirtualHost setting file (here you can set another folder as static folder instead of users/[your_path]/)

   sudo vim /etc/apache2/sites-available/000-default.conf

   Add the following lines:

   Alias /static/ /users/[your_path]/
   <Directory /users/[your_path]/>
       Require all granted
   </Directory>
   

   Then restart apache2 web server:

   sudo service apache2 restart

   You can skip this step, then all the file to be delivered should be under /var/www/html/

3. Set link delay

   sudo tc qdisc add dev eth1 root netem delay 100ms

4. Generate file for experiments

   wget pcvm1-19.genirack.nyu.edu/static/generateFile.sh
   sudo bash generateFile.sh

   This step will download a script called generateFile.sh. Two folders - cache/ and nocache/ will be created with 20 files of size from 5MB to 100MB generated.

1.3 Client

1. Install pip3

   sudo add-apt-repository universe
   sudo apt-get update && sudo apt-get install python3-pip

2. Install matplotlib using pip3

   sudo pip3 install matplotlib

   Library 'matplotlib' will be used to plot line charts.

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2 Prepare for experiments

2.1 Retrieving scripts & codes

1. Login to client node, and direct to the folder you want to execute you experiments (e.g. /users/[your_Path]/).

2. Retrieve codes for experiments using wget:

   wget pcvm1-19.genirack.nyu.edu/static/experiments/exp1_timeWithCache.py
   wget pcvm1-19.genirack.nyu.edu/static/experiments/exp1_timeWithoutCache.py
   wget pcvm1-19.genirack.nyu.edu/static/experiments/exp1_plot.py
   wget pcvm1-19.genirack.nyu.edu/static/experiments/exp2_hitrate.py
   wget pcvm1-19.genirack.nyu.edu/static/experiments/exp2_plot.py

   Note: Please check the IP address for 'cache' node. If the IP address for cache node is 10.10.1.1, so you need to replace all 10.10.1.2 with 10.10.1.1 for any involved experiment code retrieved above.

2.2 Check if ATS works

1. Login to cache node

2. Check status

   sudo /etc/init.d/trafficserver status

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3 Run experiments

3.1 Experiment 1

Now there are no cached object in proxy server, we can run this:

python3 exp1_timeWithoutCache.py

The result will be written into ./result/timeWithoutCache.txt, each line is a pair of file size and latency (in seconds), separated by a 'tab'.

Then to measure latencies to retrieve files with cache:

python3 exp1_timeWithCache.py

Similarly, the result will be recorded as ./result/timeWithCache.txt.

Eventually we can get the plot of cache vs no-cache by:

python3 exp1_plot.py

The plot will be generated as ./result/exp1.png

Our plot look like this:

3.2 Experiment 2

First to get the average latency for a file of fixed size as a function of hit rate, execute the following command:

# example: python3 exp2_hitrate.py -l 100 -s 10
python3 exp2_hitrate.py -l [loop times] -s [file size]

The result will be recorded as ./result/latency_hitrate_[file size].txt.

Then to get a plot of latency as a function of hit rate, run the following command:

python3 exp2_plot.py -s [file size]

Note: [file size] here should be same as the value when you run exp2_hitrate.py.

The plot will be generated as ./result/exp2_[file szie]MB.png

Our plot look like this: