TWIST.Sensor Web Interface Tutorial

This tutorial explains how the TWIST web interface can be used to schedule and control jobs on the TWIST testbed at TKN. It shows how the TinyOS 2 Oscilloscope application is installed on some of the Tmote Sky nodes, describes how a serial connection between a sensor node in the testbed and a remote user client is established and how one can use the cURL command line tool to automatically control some of the testbed features.

Prerequisites

To access the TKN instance of the TWIST web interface you need to have registered an account. If you are not yet registered, go to the TWIST web interface where you will see a welcome page as shown in Figure 1. Make sure that your browser has cookies enabled and click on “New account”. In the form fill in your name, email address and choose a username (at least 6 characters) and a password. Make sure you confirm the password and answer the spam control question. Then press the “Request” button; if you filled in the form correctly you will see a new page saying “Successful account request”. The last step in obtaining an account is in the responsibility of the administrator, and you will be notified by email when your account has been activated.

The TWIST Web Interface login page.

Figure 1: The TKN instance of TWIST Web Interface.

Meanwhile you might want to take a look at the TinyOS [2] tutorials, because the following sections assume that you can compile a TinyOS 2 application, that you know the TinyOS 2 tutorials [3], and have successfully reproduced the steps described in tutorials 4 [4] and 5 [5] locally (with some sensor nodes attached to your PC/laptop).

Installing a TinyOS Image

In this section we install the TinyOS 2 Oscilloscope application on a set of Tmote Sky nodes in the TKN TWIST testbed. The Oscilloscope application is described in the TinyOS 2 tutorial 5 [5]. After you have compiled the application with make telosb open a web browser and access the TWIST web interface. Press the “Login” button, enter your username and password and then click on “Sign in”. You will see a welcome page where you have three options: manage and update your account settings (“My Info”), schedule and control jobs in the testbed (“Jobs”) or logout (“Logout”). Click on “Jobs” and you will see a list of scheduled jobs, i.e. the currently active jobs as well as pending future jobs. Take a close look at the list and find a time period for which Tmote/TelosB nodes are not reserved by someone else. Then click on “Add” and you will see the Job Management page as shown in Figure 2.

Managing a job with the TWIST Web Interface

Figure 2: Managing a job with the TWIST Web Interface.

Under “Platforms” select Tmote; then choose a “Start/End date” and “Start/End time” such that the time interval is not overlapping with other jobs, which you checked in the previous step. You cannot make a real mistake here, because the system will automatically check for and not permit jobs that are overlapping in time if they use the same mote platform. However, different platforms (eyesIFX vs. Tmote) may be used concurrently. In the field “Description” enter a short note on what you plan to do in your job, such as “Testing the T2 Oscilloscope application”, then click on “Add”. If the time interval that you entered was accepted you will be taken back to the list of scheduled jobs, otherwise you get an error message and need to adapt the values.

The list of “Scheduled jobs” should now include your job. Your entry is likely to have gray background colour, meaning that it is registered but not yet active. The current system time is always shown in the upper right corner of the page and once your job becomes active – its start time is shown in the column “Start” – the background colour of your entry will turn yellow (you need to click the reload button of your browser).

When your job is active apply a tick mark at the left side of the entry and press the “Control” button at the bottom (the “Edit” button would be used to change the time of your job and with the “Delete” button you can remove your job).

Hint

When your job is active (during a experiment) you can still extend its “End time” by clicking on “Edit” on the “Jobs” page, provided that the new “End time” does not overlap with other registered jobs.*

After you have clicked the “Control” button you will see the page for controlling your active job as shown in Figure 3:

Controlling an active job.

Figure 3: Controlling an active job.

This page is divided into the list of Tmote node IDs available in the testbed (“Available reserved resources”), a section for submitting up to three different program images to be programmed on a subset of the nodes (“Job configuration”) and a set of buttons (on the bottom, not shown in Figure 3) to perform some actions, such as installing the image(s) on the nodes.

For the TinyOS 2 Oscilloscope application we want to install the Oscilloscope program image on some Tmote nodes, and one node will need to act as gateway and will be programmed with the TinyOS 2 BaseStation application (see TinyOS 2 tutorial 5 [5]). Because we will install two different application images, in the “Job configuration” field we will use two of the three “Control group” sections: the “Control group 1” section for the Oscilloscope application and the “Control group 2” section for the BaseStation application.

In the “Control group 1” section, enter in the “Node list” field a whitespace-separated list of the node IDs on which the the Oscilloscope is to be programmed, let’s say 10 11 12. For convenience you can copy & paste from the list of IDs shown on top in the “Available reserved resources” list. Then click on the “browse…” button next to the “Image” field just below the “Node list” field. Select the Oscilloscope image, which is the main.exe in your local tinyos-2.x/apps/Oscilloscope/build/telosb (you must have compiled the Oscillocope application with “make telosb” before). The “SF Baudrate” and “SF Version” fields control whether a SerialForwarder will be started for all nodes in the respective “Node list”. Since we only need a SerialForwarder for the BaseStation application, we don’t change the values (leaving it “None”, “TinyOS 2.x”). Finally, “Channel” is the IEEE 802.15.4 channel to be used by the Tmote Sky radio CC2420 (if you change the channel for the Oscilloscope application, make sure that you do the same for the BaseStation application). In fact, the value of the CC2420_DEF_CHANNEL symbol inside your progam image will be replaced by the value of the “channel” field and thus, if your application includes the TinyOS 2 CC2420 radio stack, you can still modify the default radio channel after you have compiled the image.

Hint

The node ID is another symbol that is modified for each node individually before programming the image. It is accessible via TOS_NODE_ID in a TinyOS application.*

We use the “Control group 2” section for installing the BaseStation program image on another node. In the “Node list” field enter 13 (or whichever node ID you want to use for the BaseStation application) and under “Image” click “browse…” and select the main.exe from your local tinyos-2.x/apps/BaseStation/build/telosb folder (you must have compiled the BaseStation application with “make telosb” before). Because we want to later establish a serial connection to the BaseStation node, select the pull-down menu under the “SF Baudrate” field and choose a serial baudrate. Whenever this field has a value other than None a SerialForwarder will be started for all nodes in the respective “Node list”. The default baud rate for the “TelosA”, “,TelosB” and “Tmote” platforms is 115200 baud.

Hint

You can change the baud rate for a telos node by modifying tinyos-2.x/tos/platforms/telosa/TelosSerialP.nc (this file is included by telosa, telosb and tmote platform). Make sure you recompile your application after changing the file.*

The “SF Version” field defines the version of the Serial Forwarder protocol. Because we are using a TinyOS 2 applications select “2” (for a TinyOS 1 application you would select “1”). If the “SF Baudrate” field is None then the “SF Version” is ignored. Finally, make sure you select the same “Channel” as the one for the Oscilloscope application. Your configuration should now look like the one shown in Figure 4.

An example configuration of the "Job Configuration".

Figure 4: An example “Job Configuration”: the Oscilloscope application is to be installed on nodes 10,11 and 12, the BaseStation application on node 13. A 115200 baud serial connection to the BaseStation will be established using SerialForwarder version 2. The Oscilloscope application will use IEEE 802.15.4 channel 26 for radio communication.

To actually program the images on the nodes scroll down, press the “Install” button and wait. After not much longer than 1 minute you should see a page with the “Execution log”. Check for possible errors (any line “Could not find symbol […] ignoring symbol” is only telling you that the respective symbol was not found/changed in the application image) and scroll down to the bottom where you can find a summary of the “Install” operation. Here you can also see that a SerialForwarder has been started for node 13:

To forward SF e.g. for node 13 use: ssh -nNxTL 9013:localhost:9013 twistextern@www.twist.tu-berlin.de

In the next section we will establish an ssh tunnel to the TWIST server and connect to the SerialForwarder of the BaseStation node. The remainder of this section summarizes the fields and options for controlling an active job over the web interface.

The following table describes the fields in the “Job configuration” section:

Field Meaning
Node list Whitespace separated list of node IDs on which the image will be programmed
Image The image to be programmed on the nodes in the “Node list”
SF Baudrate Whether a SerialForwarder is started for each of the nodes in “Node list” and what baudrate it will use
SF version The version of the SerialForwarder: use 1 for TinyOS 1.x and 2 for TinyOS 2.x
Channel The CC2420 radio channel

The following table describes the buttons on the bottom of the “Controlling active job” page:

Button Meaning
Install Installs the image(s) on the node(s) specified in the above “Job Configuration” section; SerialForwarders will be started (if selected) and nodes are powered on
Erase Programs the TinyOS Null application on the selected set of nodes
Reset Resets (powers off & on) the selected set of nodes
Power On Cuts the USB power supply for the selected nodes
Power Off Enables the USB power supply for the selected nodes
Start SF Starts a SerialForwarder for the selected nodes
Stop SF Stops the SerialForwarder for the selected nodes
Start Tracing Stores the serial data output from the nodes in a trace file
Stop Tracing Stops storing data in a trace file

By pressing the “Start Tracing” button the serial data output from all nodes are automatically stored to a trace file. This file can be accessed via the job control page by pressing the “Traces” button (with your job checked). If you want to use automatic tracing then it is recommended that during install you select the correct “SF Baudrate” and “SF Version”. After the install process, you can then simply click on “Start Tracing” without having to manually start the serial forwards.

Exchanging Data via the Serial Connection

Through the previously described “Install” operation a SerialForwarder for the BaseStation node was started. In order for your tinyos-2.x/apps/Oscilloscope/java/Oscilloscope.java client to connect to this SerialForwarder, you first need to establish an SSH Tunnel to forward the port of the SerialForwarder to your machine. At the very end of the execution log you find the syntax for this SSH command (type it into a shell)

ssh -nNxTL 9013:localhost:9013 twistextern@www.twist.tu-berlin.de

Once you have forwarded the port you can access the remote SerialForwarder like a local one. However, when you start your client application make sure that it attaches to the correct port as specified in the SSH Tunnel (the above command forwards the remote port to your local port 9013). For example, to start the JAVA Oscilloscope client you would first need to set the MOTECOM environment variable as follows

export MOTECOM=sf@localhost:9013

Now you can start the Oscilloscope GUI by typing:

.\run

in the tinyos-2.x/apps/Oscilloscope/java directory as described in [5]. You should now see an Oscilloscope GUI like the one described in the TinyOS tutorial.

Automatic Control via cURL

cURL [7] is a command line tool that can, among other things, transfer files and POST web forms via HTTPS. It can thus be used to automate sequences of operations on the testbed, such as installing an image or powering a node off. Before you can actually control your job you need to authenticate via cURL (Step 1) and find you job ID (Step 2). Afterwards you can control your job (Step 3) and download traces (Step 4) associated with your job ID. The following steps list the relevant cURL commands.

Step 1: Authenticate

Use the following format to authenticate and store the secure cookie for the future requests (replace YOUR_USER_NAME and YOUR_PASSWORD with your username and password, respectively):

curl -L -k --cookie /tmp/cookies.txt --cookie-jar /tmp/cookies.txt -d 'username=YOUR_USER_NAME' -d 'password=YOUR_PASSWORD' -d 'commit=Sign in' https://www.twist.tu-berlin.de:8000/__login__

Note that all data fields have to be URL encoded either implicitly using –data-urlencode or explicitly (in case you have special characters in username/password)

Step 2: Find the job_id

You need to know the job_id before you can use curl to control it. This can also be done by fetching and parsing the jobs page with cURL, maybe passing the output through “tidy”

curl -L -k --cookie /tmp/cookies.txt --cookie-jar /tmp/cookies.txt https://www.twist.tu-berlin.de:8000/jobs | tidy

Step 3: Control

The following is a list of examples on how to control a job. Make sure that you replace the job_id and node IDs.

  • Erase - For job_id 346, erase nodes 12 and 13:

    curl -k --cookie /tmp/cookies.txt --cookie-jar /tmp/cookies.txt -F __nevow_form__=controlJob -F job_id=346 -F ctrl.grp1.nodes="12 13" -F erase=Erase https://www.twist.tu-berlin.de:8000/jobs/control
    
  • Install - For job_id 346, install TestSerialBandwidth on nodes 12 and 13 and start serial forwarders:

    curl -k --cookie /tmp/cookies.txt --cookie-jar /tmp/cookies.txt -F __nevow_form__=controlJob -F job_id=346 -F ctrl.grp1.nodes="12 13" -F ctrl.grp1.image=@/home/hanjo/tos/tinyos-2.x/apps/tests/TestSerialBandwidth/build/telosb/main.exe -F ctrl.grp1.sfversion=2 -F ctrl.grp1.sfspeed=115200 -F install=Install https://www.twist.tu-berlin.de:8000/jobs/control
    
  • Power Off - For job_id 346, power off nodes 12 and 13:

    curl -k --cookie /tmp/cookies.txt --cookie-jar /tmp/cookies.txt -F __nevow_form__=controlJob -F job_id=346 -F ctrl.grp1.nodes="12 13" -F 'power_off=Power Off' https://www.twist.tu-berlin.de:8000/jobs/control
    
  • Power On - For job_id 346, power on nodes 12 and 13:

    curl -k --cookie /tmp/cookies.txt --cookie-jar /tmp/cookies.txt -F __nevow_form__=controlJob -F job_id=346 -F ctrl.grp1.nodes="12 13" -F 'power_on=Power On' https://www.twist.tu-berlin.de:8000/jobs/control
    
  • Start Tracing - For job_id 346, start tracing on nodes 12 and 13:

    curl -k --cookie /tmp/cookies.txt --cookie-jar /tmp/cookies.txt -F __nevow_form__=controlJob -F job_id=346 -F ctrl.grp1.nodes="12 13" -F 'start_tracing=Start Tracing' https://www.twist.tu-berlin.de:8000/jobs/control
    
  • Stop Tracing - For job_id 346, stop tracing on nodes 12 and 13:

    curl -k --cookie /tmp/cookies.txt --cookie-jar /tmp/cookies.txt -F __nevow_form__=controlJob -F job_id=346 -F ctrl.grp1.nodes="12 13" -F 'stop_tracing=Stop Tracing' https://www.twist.tu-berlin.de:8000/jobs/control
    

Step 4: Collect data

To collect the specific trace file from archived job 336

curl -g -k --cookie /tmp/cookies.txt --cookie-jar /tmp/cookies.txt -d 'job_id=339' -d 'trace_name=trace_20080507_114824.0.txt.gz' -o trace_20080507_114824.0.txt.gz https://www.twist.tu-berlin.de:8000/jobs/archive/traces/download
[1]Vlado Handziski, Andreas Köpke, Andreas Willig, Adam Wolisz TWIST: a scalable and reconfigurable testbed for wireless indoor experiments with sensor networks. Proceedings of the 2nd international workshop on Multi-hop ad hoc networks: from theory to reality table of contents Florence, Italy SESSION: Sensor networks table of contents Pages: 63 - 70 Year of Publication: 2006 ISBN:1-59593-360-3
[2]TinyOS Homepage: http://www.tinyos.net/
[3]TinyOS Tutorials: http://tinyos.stanford.edu/tinyos-wiki/index.php/TinyOS_Tutorials
[4]TinyOS Tutorial 4 (Mote-PC serial communication and SerialForwarder): http://tinyos.stanford.edu/tinyos-wiki/index.php/Mote-PC_serial_communication_and_SerialForwarder
[5](1, 2, 3, 4) TinyOS Tutorial 5 (Sensing): http://tinyos.stanford.edu/tinyos-wiki/index.php/Sensing
[7]curl Homepage: http://curl.haxx.se/