On the way: filter and steps

Eventing 5 · 3:21

A filter decides which events an event subscription passes on, and a step changes each event before it reaches the channel, in this video by turning a JSON body into fields.

Download the mp4Recorded on 2026.2

What it covers

A filter with the JSONPath $.invoice in the subscription document
Plain-text events that the filter removes, counted in the subscription's log
Adding the json-deserialize-action step under steps
Each change built as a new version and deployed with weikio run
The subscription drawn as boxes in a row in the admin UI
The flow, the version and the state in weikio get eventsubscriptions

Commands in this video

Terminal

$ weikio run ./files-to-invoices
$ weikio run ./invoice-files
$ weikio logs sandbox/files-to-invoices -f --since 10m
$ weikio get eventsubscriptions

Transcript

0:02The flow from the source to the channel already runs end to end. This video shapes what happens on the way.
0:12Three folders on your machine build the flow.
0:15Your Weik.io installation keeps the source, subscription and channel as integrations,
0:22each at its first version.
0:23The subscription forwards every message from invoice-files to invoice-created.
0:29All four are deployed and running in devtest.
0:32Messages sit on both channels.
0:34Agent dev runs the four integrations.
0:41The middle of the flow is the subscription file, files-to-invoices.yaml.
0:46Its spec names two channels: the one it reads and the one it writes to.
0:51The empty space beside them is where the filter goes.
0:54The filter states what an event must satisfy before the subscription forwards it.
1:01The filter forwards bodies with a node at $.invoice.
1:06weikio run on the files-to-invoices folder builds version 0.1.1,
1:13and the deployment that follows latest puts it live.
1:17Nothing is dropped yet, because every message carries the node.
1:22The message becomes a note with no invoice node,
1:25the folder runs, and the note goes live.
1:29The message goes back to an invoice body, then the folder runs.
1:34A new invoice reaches the watcher again.
1:40weikio logs on the subscription reads the last ten minutes, then follows.
1:46Each drop leaves an INFO line, never an error.
1:54The next change goes into the same document.
1:57weikio run on the files-to-invoices folder builds version 0.1.2 and puts the change live.
2:05Under steps, the document lists one kamelet action: json-deserialize-action.
2:12The event runs through the steps in order, after the filter and before the channel,
2:17and json-deserialize-action opens the JSON body into fields.
2:23The subscription's page in the admin UI draws this document as a row of boxes: the channel it reads,
2:30the filter, one step and the channel it writes to, with the default error handler named below.
2:39weikio get eventsubscriptions lists the project's subscriptions. The row shows the same source and channel,
2:47now at its latest version, running in devtest.
2:55This is the whole flow: source, filter, steps, channel.
3:00The source sends invoices on its timer.
3:03The filter forwards what passes and counts the drops.
3:07The channel delivers what reaches it.
3:09Each step opens the body into fields.

Next in this track

Eventing 6 · 3:21 Dead letters