hello-snowman

hello-snowman ⛄

Sequence that reads incoming stream (input), and and modifies it by adding a text message according to the incoming data.

---

Stream is generated in stream-gen.js file, where numbers in range of <-50,50> are randomly chosen and sent as Celsius degrees to hello-snowman Instance API endpoint /input.

Our hello-snowman app will read and interpret these Celsius degrees, 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! 🥵

Running

This sample can be run only on Self Hosted Hub, go on and setup transform-hub locally for the sequence deployment.

Open three terminals and run the following commands:

The first terminal:

# start the Hub locally
scramjet-transform-hub

The second terminal:

# go to 'hello-snowman' directory
cd javascript/hello-snowman

# install dependencies
npm install

# go back to javascript/ directory
cd ../

# deploy 'hello-snowman' Sequence
si seq deploy hello-snowman

# see the Instance output
si inst output -    # nothing happens until data is sent to input

💡NOTE: Command deploy performs three actions at once: pack, send and start the Sequence. It is the same as if you would run those three commands separately:

si seq pack . -o hello-snowman.tar.gz    # compress 'hello-snowman/' directory into file named 'hello-snowman.tar.gz'

si seq send hello-snowman.tar.gz    # send compressed Sequence to STH, this will output Sequence ID

si seq start -    # start the Sequence, this will output Instance ID

The third terminal

# Start stream generator tool with Instance ID as parameter
node javascript/hello-snowman/lib/stream-gen.js <instance_id>

#
----------------------------------------
Message# 1 | Temperature measure
INPUT | -16
OUTPUT| Snowman ⛄ is freezing 🥶 Winter is coming ❄️ ❄️ ❄️ ❄️ ❄️

----------------------------------------
Message# 2 | Temperature measure
INPUT | 49
OUTPUT| Snowman ⛄ is melting! 🥵

----------------------------------------
Message# 3 | Temperature measure
INPUT | 16
OUTPUT| Snowman ⛄ is melting! 🥵

----------------------------------------
Message# 4 | Temperature measure
INPUT | -46
OUTPUT| Snowman ⛄ is freezing 🥶 Winter is coming ❄️ ❄️ ❄️ ❄️ ❄️

----------------------------------------

Output

Now you should see the output in the second terminal:

$ si inst output -

Snowman ⛄ is freezing 🥶 Winter is coming ❄️ ❄️ ❄️ ❄️ ❄️
Snowman ⛄ is melting! 🥵
Snowman ⛄ is melting! 🥵
Snowman ⛄ is freezing 🥶 Winter is coming ❄️ ❄️ ❄️ ❄️ ❄️
Snowman ⛄ is melting! 🥵
Snowman ⛄ is freezing 🥶 Winter is coming ❄️ ❄️ ❄️ ❄️ ❄️
Snowman ⛄ is freezing 🥶 Winter is coming ❄️ ❄️ ❄️ ❄️ ❄️
Snowman ⛄ is freezing 🥶 Winter is coming ❄️ ❄️ ❄️ ❄️ ❄️
Snowman ⛄ is freezing 🥶 Winter is coming ❄️ ❄️ ❄️ ❄️ ❄️
Snowman ⛄ is freezing 🥶 Winter is coming ❄️ ❄️ ❄️ ❄️ ❄️
Snowman ⛄ is freezing 🥶 Winter is coming ❄️ ❄️ ❄️ ❄️ ❄️
Snowman ⛄ is melting! 🥵
Snowman ⛄ is melting! 🥵
Snowman ⛄ is melting! 🥵