CloudEvents (CNCF)

CloudEvents is a standard event envelope for describing event data in a consistent way across services, platforms, and languages.
Instead of every team inventing its own “event wrapper”, CloudEvents defines common metadata (who produced the event, what type it is, when it happened, etc.) and a place to carry the actual payload (data).

In this course project, CloudEvents helps you build event-driven systems that are:

Easier to integrate (services agree on the same envelope)
Easier to debug (consistent fields across all events)
More interoperable (you can forward events to other tools without rewriting formats)

What CloudEvents provides

1) A uniform event envelope

A CloudEvent has standard attributes such as:

id — unique identifier for the event instance
type — the event type name (e.g., festivo.ticket.purchased.v1)
source — identifies the producer (e.g., TicketService)
time — when the event occurred
subject (optional) — a “sub-identifier”, often an entity id (e.g., ticket/123)
datacontenttype — MIME type of the payload (e.g., application/json)
data — the payload of your domain event

This makes events consistent even if services are written by different teams.

2) Transport independence

CloudEvents is not tied to one transport. The same event structure can be transported via:

HTTP
message brokers (RabbitMQ, Kafka, etc.)
storage/event logs

You still need to decide how CloudEvents are carried on your chosen transport (e.g., JSON over RabbitMQ).

3) Better tooling and observability

Because CloudEvents are standardized, it’s easier to:

log event metadata consistently
correlate events across services (using id + correlation identifiers in data or extensions)
build debugging tools (filters by type, source, subject, etc.)

CloudEvents in your project (how to think about it)

Use CloudEvents for:

Domain events your services publish (e.g., TicketPurchased, EntryGranted)
Saga/orchestration status events (e.g., SagaStarted, SagaCompleted)

Avoid using CloudEvents for:

Very internal in-process notifications that never leave a service boundary

Payload design guidelines (important for distributed systems)

Your CloudEvent’s data should be:

Small enough to be safely transported and logged
Versioned (include a version in type or in the schema)
Stable: consumers should not break when new optional fields are added
Explicit: include identifiers needed for correlation (e.g., ticketId, scanId, processId)

SDK for C#/.NET (SDK-CSharp)

The CloudEvents C# SDK provides types and helpers that make it easier to:

represent CloudEvents in code
serialize/deserialize them (e.g., JSON)
integrate them with common .NET patterns

Documentation / repository: Cloudevents/SDK-CSharp

Tip: When reading SDK docs, focus on how the SDK represents CloudEvents and how it performs serialization. The transport (RabbitMQ) is still your responsibility.

Minimal example (illustrative only)

This is a conceptual snippet showing what a CloudEvent might look like in C#. It is intentionally minimal — you should consult the SDK docs for exact APIs and best practices.

using CloudNative.CloudEvents;
 
var evt = new CloudEvent
{
    Id = Guid.NewGuid().ToString("N"),
    Type = "festivo.ticket.purchased.v1",
    Source = new Uri("service://ticket-service"),
    Subject = "ticket/123",
    Time = DateTimeOffset.UtcNow,
    DataContentType = "application/json",
    Data = new
    {
        ticketId = "123",
        ticketCode = "FEST-9Z2KQ",
        ticketType = "standard"
    }
};
 
// Serialize + publish via your messaging infrastructure.
// (Exact serialization/publishing depends on your chosen approach.)

What you should be able to answer after reading this

What problems does CloudEvents solve?
Which fields belong in the standard envelope vs. the domain payload?
How do you ensure event payloads are versionable and safe for consumers?

Deep Thought

Explorer

CloudEvents