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Multiple Cases
We are going to create a Parallel with two branches:
- the first branch accepts events with a time that is is even
- the second branch accepts events with a time that is is odd
The events produced by each branch are then sent to the event-display
service.
Prerequisites
Please refer to the sample overview for the prerequisites.
Create the Knative Services
Let’s first create the filter and transformer services that we will use in our Parallel.
apiVersion: serving.knative.dev/v1
kind: Service
metadata:
name: even-filter
spec:
template:
spec:
containers:
- image: villardl/filter-nodejs:0.1
env:
- name: FILTER
value: |
Math.round(Date.parse(event.time) / 60000) % 2 === 0
---
apiVersion: serving.knative.dev/v1
kind: Service
metadata:
name: odd-filter
spec:
template:
spec:
containers:
- image: villardl/filter-nodejs:0.1
env:
- name: FILTER
value: |
Math.round(Date.parse(event.time) / 60000) % 2 !== 0
---
apiVersion: serving.knative.dev/v1
kind: Service
metadata:
name: even-transformer
spec:
template:
spec:
containers:
- image: villardl/transformer-nodejs
env:
- name: TRANSFORMER
value: |
({"message": "we are even!"})
---
apiVersion: serving.knative.dev/v1
kind: Service
metadata:
name: odd-transformer
spec:
template:
spec:
containers:
- image: villardl/transformer-nodejs:0.1
env:
- name: TRANSFORMER
value: |
({"message": "this is odd!"})
.
kubectl create -f ./filters.yaml -f ./transformers.yaml
Create the Service displaying the events created by Sequence
apiVersion: serving.knative.dev/v1
kind: Service
metadata:
name: event-display
spec:
template:
spec:
containers:
- image: gcr.io/knative-releases/knative.dev/eventing-contrib/cmd/event_display
Change default
below to create the Sequence
in the Namespace where you want
your resources to be created.
kubectl -n default create -f ./event-display.yaml
Create the Parallel
The parallel.yaml
file contains the specifications for creating the Parallel.
apiVersion: flows.knative.dev/v1
kind: Parallel
metadata:
name: odd-even-parallel
spec:
channelTemplate:
apiVersion: messaging.knative.dev/v1
kind: InMemoryChannel
branches:
- filter:
ref:
apiVersion: serving.knative.dev/v1
kind: Service
name: even-filter
subscriber:
ref:
apiVersion: serving.knative.dev/v1
kind: Service
name: even-transformer
- filter:
ref:
apiVersion: serving.knative.dev/v1
kind: Service
name: odd-filter
subscriber:
ref:
apiVersion: serving.knative.dev/v1
kind: Service
name: odd-transformer
reply:
ref:
apiVersion: serving.knative.dev/v1
kind: Service
name: event-display
kubectl create -f ./parallel.yaml
Create the PingSource targeting the Parallel
This will create a PingSource which will send a CloudEvent with
{"message": "Even or odd?"}
as the data payload every minute.
apiVersion: sources.knative.dev/v1beta1
kind: PingSource
metadata:
name: ping-source
spec:
schedule: "*/1 * * * *"
jsonData: '{"message": "Even or odd?"}'
sink:
ref:
apiVersion: flows.knative.dev/v1
kind: Parallel
name: odd-even-parallel
kubectl create -f ./ping-source.yaml
Inspecting the results
You can now see the final output by inspecting the logs of the event-display
pods. Note that since we set the PingSource
to emit every minute, it might
take some time for the events to show up in the logs.
Let’s look at the event-display
log:
kubectl logs -l serving.knative.dev/service=event-display --tail=30 -c user-container
☁️ cloudevents.Event
Validation: valid
Context Attributes,
specversion: 1.0
type: dev.knative.sources.ping
source: /apis/v1/namespaces/default/pingsources/ping-source
id: 015a4cf4-8a43-44a9-8702-3d4171d27ba5
time: 2020-03-03T21:24:00.0007254Z
datacontenttype: application/json; charset=utf-8
Extensions,
knativehistory: odd-even-parallel-kn-parallel-kn-channel.default.svc.cluster.local; odd-even-parallel-kn-parallel-0-kn-channel.default.svc.cluster.local
traceparent: 00-41a139bf073f3cfcba7bb7ce7f1488fc-68a891ace985221a-00
Data,
{
"message": "we are even!"
}
☁️ cloudevents.Event
Validation: valid
Context Attributes,
specversion: 1.0
type: dev.knative.sources.ping
source: /apis/v1/namespaces/default/pingsources/ping-source
id: 52e6b097-f914-4b5a-8539-165650e85bcd
time: 2020-03-03T21:23:00.0004662Z
datacontenttype: application/json; charset=utf-8
Extensions,
knativehistory: odd-even-parallel-kn-parallel-kn-channel.default.svc.cluster.local; odd-even-parallel-kn-parallel-1-kn-channel.default.svc.cluster.local
traceparent: 00-58d371410d7daf2033be226860b4ee5d-05d686ee90c3226f-00
Data,
{
"message": "this is odd!"
}