kaldesai commented on code in PR #558:
URL:
https://github.com/apache/incubator-kie-kogito-docs/pull/558#discussion_r1512310087
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serverlessworkflow/modules/ROOT/pages/use-cases/advanced-developer-use-cases/event-orchestration/newsletter-subscription-example.adoc:
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@@ -0,0 +1,264 @@
+= Newsletter Subscription example in {product_name}
+
+:compat-mode!:
+// Metadata:
+:description: Newsletter subscription example in Serverless Workflow
+:keywords: kogito, workflow, serverless
+:flow_newsletter_subscription_url:
{kogito_sw_examples_url}/serverless-workflow-newsletter-subscription
+
+This example demonstrates a few features powered by the {product_name}
following the Serverless Workflow specification including:
+
+* REST Services calls via OpenAPI definitions
+* Pause and resume of a given workflow instance
+* Consuming and producing CloudEvents
+
+In a Knative environment, the services involved in this use case can be scaled
to zero and resume from the exact stage it was, saving cluster resources in the
process.
+
+The figure below illustrates the overall architecture of this use case.
+
+image::use-cases/newsletter-subscription/architecture.png[Architecture]
+
+. Once a new subscription request comes, the flow will evaluate if it's not
already subscribed.
+. If not, it will attempt to subscribe the new user and wait for the
confirmation.
+. Once a new event containing the confirmation arrives, the flow will resume
and subscribe the new user.
+. Subscriptions that are not confirmed during a configured period of time, are
considered timed-out and are automatically removed from the system.
+. By the end, a new event containing the details of the subscription is
broadcasted in the environment, so other actors can react upon it.
+
+Here we have the Newsletter Subscription workflow:
+
+.newsletter-subscription-flow workflow
+image::use-cases/newsletter-subscription/newsletter-subscription-flow.png[Workflow]
+
+.Newsletter subscription flow workflow definition
+[source,json]
+----
+{
+ "id": "subscription_flow",
+ "dataInputSchema": "subscription-schema.json",
+ "specVersion": "0.8",
+ "version": "1.0",
+ "start": "VerifyEmail",
+ "events": [
+ {
+ "kind": "produced",
+ "type": "new.subscription",
+ "name": "NewSubscriptionEvent"
+ },
+ {
+ "kind": "consumed",
+ "type": "confirm.subscription",
+ "name": "ConfirmSubscriptionEvent"
+ }
+ ],
+ "functions": [
+ {
+ "name": "subscribeToNewsletter",
+ "operation": "specs/subscription-service.yaml#subscribe"
+ },
+ {
+ "name": "confirmSubscription",
+ "operation": "specs/subscription-service.yaml#confirm"
+ },
+ {
+ "name": "deleteSubscription",
+ "operation": "specs/subscription-service.yaml#delete"
+ },
+ {
+ "name": "verifyEmail",
+ "operation": "specs/subscription-service.yaml#verify"
+ }
+ ],
+ "states": [
+ {
+ "name": "VerifyEmail",
+ "type": "operation",
+ "actions": [
+ {
+ "functionRef": {
+ "refName": "verifyEmail",
+ "arguments": {
+ "email": "${ .email }"
+ }
+ }
+ }
+ ],
+ "transition": {
+ "nextState": "ExitIfEmailExists"
+ }
+ },
+ {
+ "name": "ExitIfEmailExists",
+ "type": "switch",
+ "dataConditions": [
+ {
+ "condition": "${ .emailExists == true }",
+ "transition": {
+ "nextState": "NoSubscription"
+ }
+ },
+ {
+ "condition": "${ .emailExists == false }",
+ "transition": {
+ "nextState": "SubscribeAndWaitForConfirmation"
+ }
+ }
+ ]
+ },
+ {
+ "name": "SubscribeAndWaitForConfirmation",
+ "type": "callback",
+ "action": {
+ "functionRef": {
+ "refName": "subscribeToNewsletter",
+ "arguments": {
+ "email": "${ .email }",
+ "id": "$WORKFLOW.instanceId",
+ "name": "${ .name }"
+ }
+ }
+ },
+ "eventRef": "ConfirmSubscriptionEvent",
+ "transition": {
+ "nextState": "CheckConfirmation"
+ },
+ "timeouts": {
+ "eventTimeout": "PT3M"
+ }
+ },
+ {
+ "name" : "CheckConfirmation",
+ "type" : "switch",
+ "dataConditions": [
+ {
+ "condition": "${ .confirmed == true }",
+ "transition": "ConfirmSubscription"
+ }
+ ],
+ "defaultCondition": {
+ "transition": "DeleteSubscription"
+ }
+ },
+ {
+ "name": "ConfirmSubscription",
+ "type": "operation",
+ "actions": [
+ {
+ "functionRef": {
+ "refName": "confirmSubscription",
+ "arguments": {
+ "email": "${ .email }",
+ "id": "$WORKFLOW.instanceId",
+ "name": "${ .name }"
+ }
+ }
+ }
+ ],
+ "end": {
+ "produceEvents": [
+ {
+ "eventRef": "NewSubscriptionEvent"
+ }
+ ],
+ "terminate": true
+ }
+ },
+ {
+ "name": "DeleteSubscription",
+ "type": "operation",
+ "actions": [
+ {
+ "functionRef": {
+ "refName": "deleteSubscription",
+ "arguments": {
+ "id": "$WORKFLOW.instanceId"
+ }
+ }
+ }
+ ],
+ "end": true
+ },
+ {
+ "name": "NoSubscription",
+ "type": "inject",
+ "data": {
+ "subscribed": true
+ },
+ "end": true
+ }
+ ]
+}
+----
+
+The newsletter-subscription example involves two services:
+
+* Newsletter subscription application. It allows to create new subscriptions
and runs the workflow.
+* Newsletter subscription Backend. It allows to see the pending and the
approved subscriptions
+
+Both services provide specific user interface to allow to track what's going
on with the subscriptions
+
+[#workflow_newsletter_subscription_ui]
+== The User Interface
+As a Quarkus project, the UI resources can be placed at folder
`src/main/resources/META-INF/resources`.
+
+The Newsletter Subscription Application (subscription-flow) has a user
interface to interact with the workflow without having to rely on the command
line to push events or making HTTP requests:
+
+The used resources are available at
link:{flow_newsletter_subscription_url}/subscription-flow/src/main/resources/META-INF/resources[Newsletter
Subscription Application flow UI resources].
+
+.Newsletter subscription user interface
+image::use-cases/newsletter-subscription/newsletter-subscription-ui.png[Newsletter
subscription UI]
+
+The Newsletter Subscription backend (subscription-service) has a user
interface to see the state of the existing subscriptions
+
+The used resources are available at
link:{flow_newsletter_subscription_url}/subscription-service/src/main/resources/META-INF/resources[Subscription
service UI resources].
+
+.Newsletter subscription backend user interface
+image::use-cases/newsletter-subscription/newsletter-subscription-backend-ui.png[Newsletter
subscription backend UI]
+
+== Executing the workflows
+
+In a command terminal, clone the `kogito-examples` repository, navigate to the
cloned directory, and follow
link:{kogito_sw_examples_url}/serverless-workflow-newsletter-subscription/README.md#running-on-knative[these
steps]:
+
+[source, bash]
+----
+git clone https://github.com/apache/incubator-kie-kogito-examples.git
+
+cd
kogito-examples/serverless-workflow-examples/serverless-workflow-newsletter-subscription
+----
+
+=== Architecture
+
+The following diagram shows the architecture for this use case:
+
+. Every time a workflow needs to program a timer for a given timeout, a cloud
event is sent to the {job_service_xref}#integration-with-the-workflows[job
service] for that purpose.
+. When a timer is overdue, a rest call is executed to notify the workflow,
which then must execute according to the given state semantic.
+. Workflow and job status changes are propagated to the {data_index_xref}[data
index service] via cloud events.
+
+.Knative Workflow with Job Service architecture
+image::use-cases/newsletter-subscription/newsletter-subscription-Architecture.png[]
+
+* *subscription-flow:* Is the Quarkus Workflow Project that contains the
workflows that must be maven build, and deployed into the kubernetes cluster.
+
+* *subscription-service:* Is the Quarkus Workflow Project that contains the
backend operations, that must be maven built, and deployed into the kubernetes
cluster.
+
+* *jobs-service-postresql:* Is the job service that will be deployed into the
kubernetes cluster.
Review Comment:
```suggestion
* *jobs-service-PostgreSQL:* Is the job service that will be deployed into
the kubernetes cluster.
```
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