Self Hosted Hub Installation

Every Sequence app needs to be packaged (compressed) before sending to STH. Package is a simple TAR archive and our STH CLI has a special command to pack an app directory into a Sequence tarball.

Note: any time, you can display STH CLI help by issuing terminal command si help (for general help). For more information on a specific command, type help + command-name (ie. si sequence help)

Please open new terminal window (and keep the first one open with STH running). Then issue following commands in the root directory of this repository: Pack directory hello-snowman into archive hello-sequence.tar.gz:

There is no output shown in the terminal but you can verify with ls that tarball package is created inside samples directory. Please move to the next step.

Send hello-snowman.tar.gz to the running STH (default localhost API endpoint will be used by the CLI send command) by issuing following command:

Note: if you receive reply: Request ok: http://127.0.0.1:8000/api/v1/sequence status: 422 Unprocessable Entity, it means that STH Docker images are not yet pulled from DockerHub. Please wait 2-3 minutes and try to issue si sequence send command again. We are working on fixing this issue in the next STH release. Also, if you keep receiving docker errors you can start sth without docker: scramjet-transform-hub --no-docker

If you encounter any problems or issues while using our platform, please visit our Troubleshooting section, where some of the problems are already known and described. You are also very welcome to log an issue/bug on GitHub any time.

The output will look similar to this one:

Now we have uploaded Sequence to STH. Each time a Sequence is being uploaded, a random ID (GUID) number is assigned to it, in this case our Sequence ID is:

_id: 'cf775cc1-105b-473d-b929-6885a0c2182c'

STH also exposes REST API endpoint for each Sequence and this is also described in this response. Exposed Sequence ID allows us to move to the next step where we will start the Sequence.

We can now use Sequence ID to start uploaded Sequence. The command is si seq start <sequence_id>. To make our users life easier we provided an alias for Sequence ID: - thanks to which you can skip copy&paste ID, and simply type: si seq start -. This CLI functionality replaces - argument with the last item the user interacted with or select ed.

You can also pass arbitrary number of parameters by providing them after <sequence_id>, in case of our hello-snowman no parameters are used. Use the following command to start the Sequence:

or

The output will look similar to this one:

Once Sequence is up and running, it becomes an Instance. The Instance also receives its own unique ID (GUID).

In this case Instance ID is: id: 'e70222d1-acfc-4e00-b046-4a3a9481c53b'. Of course, Sequences can be run multiple times. Each run will create a separate Instance with a distinct Instance ID.

We want to make your life easier and for this very example, we have prepared a special Node.js app that will generate a stream of simple messages and send them to our running Instance of hello-snowman.

For fun, our stream generator will send simple text messages containing temperature readings from artificial weather station. Temperature value will be generated randomly in range of <-50,50> degrees Celsius. Our hello-snowman app will read and interpret these messages and will inform us about state of our Snowman:

• if temperature will be 0 or below, Sequence will return message: Snowman ⛄ is freezing 🥶 Winter is coming ❄️ ❄️ ❄️ ❄️ ❄️
• in the other case (temperature above 0 degrees), Sequence will return message: Snowman ⛄ is melting! 🥵

To run this app, please execute the following command from the root of our directory node ./tools/stream-gen-tool/stream-gen.js <instance_id>. In our case this would look like this:

The output will look similar to this one:

Our Sequence generator app does two things here:

• Sends stream of messages; each one containing number with temperature value
• Reads output from STH API that is generated by our hello-snowman Sequences

Separately, you can also open a new terminal window and see log of this particular instance with command si instance log <instance_id>. In our case this would be:

The sample output will be similar to this one:

Once hello-snowman Sequence is up and running we can check the output that the Instance produces, we have also sent some input data to this Instance to consume. To see what the program does to this data use the command below, it will show you the Instance output after data transformation. Open one more terminal and paste:

or by using alias

This is an example output that you should get: