For more than a decade, web APIs have replaced the previous generation of web services. Throughout this period of growth, most APIs have been restricted to request-response over HTTP. We are now seeing a move back to eventing with the popularity of webhooks. Additionally, streaming is becoming another option for connecting services, apps, and devices. In this talk, we will look at the opportunities that event-based APIs and streaming offer and how our software architecture is evolving to handle these new styles of API interaction.

1. Beyond REST: Moving to
Event-Based APIs and Streaming
GlueCon 2019
James Higginbotham
james@launchany.com
@launchany

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Introduction
• Executive API Consultant
• API architecture, strategy,
and design
• Based in Colorado Springs
• Across multiple verticals:
– Commercial Insurance
– Healthcare
– Hospitality
– Finance and Banking
– Travel
– Airline

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Tracing the Evolution of REST APIs
Photo by Jason Leung on Unsplash

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APIs Solve a Variety of Use Cases
Customer
Experience
Worker
Experience
Supplier/Partner
Experience
Integration Utility

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API Design is an architectural
concern that combines
business, product design, and
software engineering

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REST APIs are stuck in the land of CRUD

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?
Roy Fielding’s Warning
“The REST interface is designed to be
efficient for large grain hypermedia data
transfer, optimizing for the common
case of the Web, but resulting in an
interface that is not optimal for other
forms of architectural interaction.”
- Roy Fielding
- https://www.ics.uci.edu/~fielding/pubs/dissertation/software_arch.htm#sec_1_5

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APIs Require Different Interaction Styles
Request/
Response
Request/
Acknowledge
Batch-Based
Publish/
Subscribe
Message
Streaming

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Styles of API Eventing and Streaming
Photo by Andrew Ridley on Unsplash

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Messaging and Streaming Infrastructure

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Queues and Topics
Point-to-Point Messaging
via Queues
Fanout (Pub/Sub)
via Topics
Component
MessageBroker
Component
Publisher
MessageBroker
Subscriber
Subscriber
Subscriber
Component
Message B
Message A
Message A
Message B
Message A
Message A
Message A
Message A

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Messaging Infrastructure

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Messaging and Streaming Infrastructure

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Distributed Logs
Topic A
Record1
Record2
Record3
Record4
Record5
Record6
Record7
Record8
Record9
Record10
Consumer BConsumer A

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Streaming Infrastructure

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From API Polling to API Eventing
https://streamdata.io

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API Eventing and Streaming Styles

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GraphQL Subscriptions
Source: https://graphql.github.io/graphql-spec/June2018/#sec-Subscription

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API Eventing and Streaming Styles

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gRPC Client and Server Streaming
Source: https://grpc.io/docs/tutorials/basic/python.html#bidirectional-streaming-rpc

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API Eventing and Streaming Styles

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Server-Sent Events (SSE)
Source: https://developer.mozilla.org/en-US/docs/Web/API/Server-sent_events/Using_server-sent_events

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API Eventing and Streaming Styles

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Websockets
Source: http://apress.jensimmons.com/v5/pro-html5-programming/ch7.html

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Websocket Subprotocols
Source: https://www.iana.org/assignments/websocket/websocket.xml

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API Eventing and Streaming Styles

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Webhooks for HTTP POST Callbacks

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Resthooks.org

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Opportunity #1:
Events and Streams Create Innovation
Photo by Diego PH on Unsplash

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GitHub: Creating a CI/CD Marketplace
Source: https://github.com/launchany/event-hub/settings/hooks/new

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Opportunity #2:
Events and Streams Enable Collaboration
Photo by Matteo Vistocco on Unsplash

32. When APIs Meet Jobs-To-Be-Done
{
…
"_links": {
“self": {"href": "/approval-requests/d796f2d0eb72492bb088"},
“approve": {"href": "/approval-requests/d796f2d0eb72492bb088/approve"},
“decline": {"href": "/approval-requests/d796f2d0eb72492bb088/decline"},
},
…
}
{
"event": {
"type": "approved",
…
}
}

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Messaging Platform Events

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Bi-directional Webhooks
Webhook
Dispatcher
Workflow
Engine
Messaging
App
Webhook
Receiver
Webhook
Receiver
Webhook
Dispatcher
HTTP POST /hooks/messages
HTTP POST /hooks/workflow
{
“lastState”: “review”,
“newState”: “approved”,
“workflowId” : …
}
{
“message”: “Can you please review?”,
“link”: “/articles/12345”,
“workflowId” : …
}
Ash: “Can you please review?”
Julie: Approved

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Opportunity #3:
Events and Streams Operationalize Data
Photo by Mika Baumeister on Unsplash

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Today’s Data Pipeline: From ETL to ELQT

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Evolving Your Software Architecture
Photo by Ashkan Forouzani on Unsplash

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APIs Often Start Simple

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Capabilities and Outcomes First, API Design Next
• Track a project from start to completion
• Subdivide a project into tasks
• Mark tasks as completed
• View incomplete tasks
• View active projects
• View archived projects
• Add collaborators to a project
• POST /projects
• POST /projects/{projectId}/tasks
• POST /projects/{projectId}/tasks /{taskId}/complete
• GET /tasks?status=incomplete
• GET /projects?status=active
• GET /projects?status=archived
• POST /projects/{projectId}/members

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As the Organization Grows, Complexity Increases

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The Journey Toward an Enterprise API Platform
Offers API
Inventory API
Orders API
Identity API
Accounts API
Rewards API
Partners
Internal
Developers
Public App
Developers
Customers
Third-party
Approved Apps
Redeem Svc
Register Svc
Avail Offers Svc
Check Inv Svc
Ship Receive Svc
Create Order Svc
Order History Svc
Profile Svc
Permissions Svc
Friends n Fam Svc
Redemption Stream
New Acct Stream
Inv Low Stream
Order Proc Stream

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The Evolving Enterprise Platform

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Move Your Platform Beyond Request-Response APIs
• APIs deliver capabilities through commands and queries
• Events and streaming provide extensibility
• Discovery via OpenAPI Spec + AsyncAPI (https://asyncapi.com)
• Function-as-a-Service (FaaS) and iPaaS are the integration glue
Rewards API
Redeem Svc
Register Svc
Redemption Stream
Redemption Event
onRedemptionEvent()
APIs Capabilities
(Services)
Streaming
& Eventing
Functions-as-a-Service
& Stream Processors
Redemption Processor

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AsyncAPI: Eventing and Streaming Discovery

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Describing Streaming Data Using AsyncAPI (w/ Apache Avro)

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https://launchany.com/canvas
Introducing the Microservice Design Canvas v2

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Microservice Design Card v2
https://launchany.com/canvas

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Toward a Future of Faster Integration
Photo by Dlanor S on Unsplash

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GitHub Actions: Eventing Meets Serverless
Source: https://github.com/stefanprodan/gh-actions-demo

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The History of Low Code/No Code
Source: https://www.youtube.com/watch?v=I5WEH8jh8Hk
Client-Server SOA/SOAP

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The Future is API Integration (again)

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James Higginbotham
james@launchany.com
@launchany
https://launchany.com/canvas
https://apideveloperweekly.com