The passthrough example is the simplest possible configuration of thremor. It shows the very basic building blocks: Onramp, Offramp, Binding, Mapping and Pipeline.
The onramp we use is a websocket onramp listening on port 4242, it receives JSON formatted messages.
onramp:
- id: input # A unique id for binding/mapping
type: ws # The unique type descriptor for the onramp ( websocket server here)
codec: json # The underlying data format expected for application payload data
config:
port: 4242 # The TCP port to listen on
host: '0.0.0.0' # The IP address to bind on ( all interfaces in this case )It connects to the pipeline example in the example.trickle file using the trickle query language to express its logic.
The offramp we used is a console offramp producing to standard output. It receives JSON formatted messages.
offramp:
- id: stdout-output # The unique id for binding/mapping
type: stdout # The unique type descriptor for the offramp ( stdout here )
codec: json # The underlying data format expected for application payload data
config:
prefix: '>> ' # A prefix for data emitted on standard output by this offrampThe binding expresses those relations and gives the graph of onramp, pipeline and offramp.
binding:
- id: passthrough # The unique name of this binding template
links:
'/onramp/input/{instance}/out': # Connect the inpunt to the pipeline
- '/pipeline/example/{instance}/in'
'/pipeline/example/{instance}/out': # Connect the pipeline to the output
- '/offramp/stdout-output/{instance}/in'Finally the mapping instanciates the binding with the given name and instance variable to activate the elements of the binding.
select event from in into out
Execute a the passthrough query against a sample input.json
$ tremor-query -e input.json example.trickle
>> {"hello": "world"}Deploy the solution into a docker environment
$ docker-compose up
>> {"hello": "world", "selected": false}
>> {"hello": "again", "selected": true}Inject test messages via websocat
Note: Can be installed via
cargo install websocatfor the lazy/impatient amongst us
$ cat inputs.txt | websocat ws://localhost:4242
...
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