Preliminary Steps

You need to get the tools to run the emulator. Follow the instructions in Get Source to download the tools and make them available for execution.

You can see the instructions for getting the JAMScript working with docker containers here.

If everything is setup properly, you should be able to type djam or jam and you should see a menu of sub commands available under each of them.

Compiling and Running JAMScript in Containers

To compile a JAMScript program, do the following.

  1. Write or get a JAMScript program. The easiest is to download the JAMSamples. Run git clone samples to download many example programs into a samples folder.
  2. Change to a folder containing a valid JAMScript program. cd samples/JData/String_Log will change to the folder containing the string logging example.
  3. To compile this program: djam compile stringlog.*.
  4. After a successful compile, you should see stringlog.jxe in the folder. If not, the compilation did not succeed. You should have seen some error messages in the console to that effect.
  5. Once you have compiled the sample program, you can run the program in different ways: in a device, fog, or cloud. When you run in a device, you can specify different number of C nodes as well. By default, the djam run sub command creates a single C node.

To run a device using the stringlog.jxe with 2 C nodes under the app name q5 in background, use the following command.

djam run stringlog.jxe --num=2 --app=q5 --bg

To see the status of the docker JAMScript execution, run the following command.

djam list

You should see something like the following.

      ID         NAME      PROGRAM         HOST         D-STORE       TYPE C-NODES    TMUX-ID

      q5           q5    stringlog ec0cd9fa0887     docker:6379      cloud      -- u-501-cloud-5-cloud
      q5           q5    stringlog ad38d5fb718a     docker:6379     device       2 u-501-device-13-dev
      q5           q5    stringlog 4e0c4d9a7732     docker:6379     device       1 u-501-device-17-dev
      q5           q5    stringlog 443981d1dbbd     docker:6379     device       1 u-501-device-19-dev
      q5           q5    stringlog 7059b7d955a6     docker:6379     device       1 u-501-device-21-dev
      q5           q5    stringlog cf46d982d28b     docker:6379     device       1 u-501-device-25-dev
      q5           q5    stringlog e8d1605639d9     docker:6379     device       1 u-501-device-27-dev
      q5           q5    stringlog 79a02ca4934d     docker:6379     device       1 u-501-device-29-dev
      q5           q5    stringlog f011f39a80d8     docker:6379     device       1 u-501-device-31-dev
      q5           q5    stringlog e9fe93e89c71     docker:6379     device       1 u-501-device-33-dev
      q5           q5    stringlog c3cf5c274ab9     docker:6379     device       1 u-501-device-35-dev
      q5           q5    stringlog 45c292e451de     docker:6379        fog      -- u-501-fog-7-fog

The second line corresponds to the device created by the previously issued command. It is created under the ID q5. Also, the NAME is same as the ID. The HOST gives the docker ID for the container running the device. The D-STORE shows the URL for the data depot used by the device. By default the djam puts a data depot inside each container at the default port. The TMUX-ID shows the tmux terminal that runs the program. To connect to the terminal issue the following command.

jam term u-501-device-13-dev

To detach from the terminal, press Ctrl-B and d. Some djam subcommands and interchangeable with the jam subcommands (e.g., jam term djam term are the same).

You can start a whole topology using a script like the following.

djam init --zones=3 --indelay=3:1 --outdelay=5:3 --cldelay=30:5

djam run stringlog.jxe --cloud --app=q5 --bg

for i in `seq 1 3`; do
    djam run stringlog.jxe --fog --app=q5 --bg

for i in `seq 1 12`; do
    djam run stringlog.jxe --app=q5  --bg

The above script, is setting up a network with three zones. The --indelay in the first line is specifying the delay within a zone. The --outdelay is specifying the delay across two different zones. The --cldelay parameter specifies the delay between the cloud and a machine (fog or device) in a zone. You will notice that all machines (cloud, fogs, and devices) are started with the same application name (i.e., q5). This is necessary for the nodes to create a single topology. You can delete all nodes in the topology, using the following command.

djam kill q5

If you want to see how the delay is setup among the nodes, use the djam test command. It should create a test topology of bare nodes (i.e., no JAMScript program is running in them). You can see them running by issuing the docker ps command, they should have -test in their names. Log in to a device, fog, and cloud test node and run a ping to a corresponding test node. You can see the network delay. To obtain the IP address of a node, run hostname -I while in the node.

Description of Docker JAMScript Tools