Sending and receiving an event by hand

This page aims to clarify how to send and receive data to Stream Machine with the Avro serialization wire format, without any Stream Machine specific code.

Stream Machine uses only standard open-source formats (like Avro and Json-schema), authentication systems (OAuth2) and transport layers (http/2 and websocket and grpc).

This tutorial uses httpie as a convenient substitute for curl.

First create a stream.

$ strm create stream by-hand --save
  "ref": {
    "billingId": "demo8542234275",
    "name": "by-hand"
  "enabled": true,
  "limits": {
    "eventRate": "999999",
    "eventCount": "999999999"
  "credentials": [
      "clientId": "w0qu00hwl644b...",
      "clientSecret": "OygfdpwBqoekL..."
Use strm listen web-socket by-hand to get some feedback on the events your sending.

Request an OAuth 2.0 id token that you need to be able to send events to a certain stream.

idToken=$(http \
  clientSecret='OygfdpwB....' | jq -r .idToken)

You can inspect the resulting $idToken in to see what we store inside it.

We’ve generated some random data with this tool for the clickstream demo schema.

  "strmMeta" : {
    "eventContractRef" : "streammachine/clickstream/1.0.0",
    "nonce" : null,
    "timestamp" : null,
    "keyLink" : null,
    "billingId" : null,
    "consentLevels" : [0]
  "producerSessionId" : "producer",
  "url" : "url",
  "eventType" : "click",
  "referrer" : "bla",
  "userAgent" : "bla",
  "conversion" : 0,
  "customer" : { "id" : "bla" },
  "abTests" : ["a","b"]
This is the json serialization format of Avro. Our client drivers use the much faster and more compact Avro binary format.

And use it to post some random data:

cat demo.json | http post\
  authorization:"Bearer $idToken" \

HTTP/1.1 400 Bad Request

Field: 'url' in event with schema: 'streammachine/clickstream/1.0.0' with value: 'url'
  doesn't match regex: '^(https?|ftp|file)://[-a-zA-Z0-9+&@#/%?=~_|!:,.;]*[-a-zA-Z0-9+&@#/%=~_|]'

This is as expected. Stream Machine gives an indication that a validation failed. This is an example of the mechanism that Stream Machine provides to indicate to the data producers that their data doesn’t conform to the rules of the Event Contract.

Modify the url field in demo.json to become any valid url (like, and try to send it again:

cat demo.json | http post\
  authorization:"Bearer $idToken" \
HTTP/1.1 204 No Content

204 is the http status code that Stream Machine returns when the event has been accepted and processed.

Curl instead of httpie

When using curl instead of httpie it is possible to observe the http/2 response, indicating the use of http/2 with its much higher throughput.

curl -v \
    -H "authorization: Bearer $idToken" \
    -H "Strm-Schema-Id:streammachine/clickstream/1.0.0" --data-binary @demo.json

* Using HTTP2, server supports multiplexing
* Connection state changed (HTTP/2 confirmed)
> POST /event HTTP/2
> Host:
> strm-schema-id:streammachine/clickstream/1.0.0
> content-length: 434
< HTTP/2 204

Decrypting data

First, create a decrypted stream:

strm create stream --derived-from by-hand --levels 2 --save
  "ref": { "billingId": "demo8542234275", "name": "by-hand-2" },
  "consentLevels": [ 2 ],
  "consentLevelType": "CUMULATIVE",
  "enabled": true,
  "linkedStream": "by-hand",
  "credentials": [
    { "clientId": "hx7hj7w5mwkbybdrwhale1hvq0r6qk",
      "clientSecret": "#Fs4DkVtJh(2uss#062hGuzTLW9u5t" }

Send an event as describe above with curl or httpie. Observe the decrypted attributes in the events received from the web-socket.

$ strm listen web-socket by-hand-2

  "strmMeta": {
    "eventContractRef": "streammachine/example/1.3.0",
    "nonce": 15082564,
    "timestamp": 1629192833072,
    "keyLink": "55c2f72b-cff8-4814-ae33-e125c77e50f9",
    "billingId": "demo8542234275",
    "consentLevels": [ 0, 1, 2, 3 ]
  "uniqueIdentifier": "unique-14",
  "consistentValue": "session-740",
  "someSensitiveValue": "ASB9bJrnYjxjNF5Txc+Wc2k1zvzFAmE03SYK499WK5Du",
  "notSensitiveValue": "not-sensitive-39"
That most fields are decrypted, but the someSensitiveValue field is not because that is of consent level 3 (see the event contract). If the event had not contained 2 in its consent levels, we wouldn’t even have seen the event in this decrypted stream.

And finally, to clean up the resources:

strm delete stream by-hand --recursive

# note that everything that has been deleted is returned from this call.

Receiving from the websocket without the strm cli.

If you want to retrieve json serialized events without using the strm listen web-socket tool, do these steps.