We built event-driven user interfaces for decades. What about bringing the same approach to mobile, web, and IoT backend applications? You have to understand how data flows and what is the propagation of changes, using reactive programming techniques. You can focus on the core functionalities to build and the relationships among the resources you use. Your application behaves similarly to a “spreadsheet”, where depending resources are updated automatically when something “happens”, and is decomposed into scalable microservices without having to manage the infrastructure. The resulting architecture is efficient and cost effective to run on AWS and managing availability, scalability and security becomes part of the implementation itself.

1. Building Event-Driven
Serverless Applications
Danilo Poccia
Technical Evangelist
@danilop
danilop

2. Virtual
Machines

3. Virtual
Machines
Containers

4. Virtual
Machines
Containers Functions

5. Event-Driven in the Front End

6. Name
Email
Create New User
Submit
Check the “Name” syntax is right
(only letters and spaces)
Check the “Email” syntax is right
(something@some.domain)
Create the new user using
provided Name and Email
User Interface Actions

7. Name
Email
Create New User
Submit
Check the “Name” syntax is right
(only letters and spaces)
Check the “Email” syntax is right
(something@some.domain)
Create the new user using
provided Name and Email
User Interface ActionsObservers
Target Action

8. What about the Back End ?

9. Users

10. Internet
Users

11. Back End
Logic
Internet
Users

12. Back End
Data
Back End
Logic
Internet
Users

13. Back End
Data
Application Back End
Back End
Logic
Internet
Users

14. Application Back End
Web Browsers
Back End
Data
Back End
Logic

15. Application Back End
Web Browsers
Mobile Apps Back End
Data
Back End
Logic

16. Application Back End
Web Browsers
Mobile Apps
IoT Devices
Back End
Data
Back End
Logic

17. Application Back End
Web Browsers
Mobile Apps
IoT Devices
Other Services
Back End
Data
Back End
Logic

18. Application Back End
Files
Databases
Web Browsers
Mobile Apps
IoT Devices
Other Services
Back End
Logic

19. HTML, CSS, JavaScript
& Multimedia Content
API Calls
Application Back End
Web Browsers
Mobile Apps
IoT Devices
Other Services
Files
Databases
Back End
Logic

20. API Calls
Application Back End
HTML, CSS, JavaScript
& Multimedia Content
Web Browsers
(JavaScript)
Mobile Apps
IoT Devices
Other Services
By using JavaScript,
Web Browsers can behave
like the other clients,
such as Mobile Apps
or IoT Devices
Files
Databases
Back End
Logic

21. API Calls
Application Back End
HTML, CSS, JavaScript
& Multimedia Content
Web Browsers
(JavaScript)
Mobile Apps
IoT Devices
Other Services
Files
Databases
Back End
Logic

22. Client
Application
API Calls
Application Back End
HTML, CSS, JavaScript
& Multimedia Content
The Client Application
can be a Web Browser,
a Mobile App,
an IoT Device,
or another Service
We can now decouple the
back end implementation
from the device
used by our users
Files
Databases
Back End
Logic

23. Client
Application
API Calls
Application Back End
HTML, CSS, JavaScript
& Multimedia Content
The Client Application
can be a Web Browser,
a Mobile App,
an IoT Device,
or another Service
Files
Databases
Back End
Logic

24. Functions as your API

25. Context
Function
Event
AWS Lambda
Result
RequestResponse
Function
Invocation
Lambda API Call
AWS Lambda Functions
Synchronous Invocations

26. Context
Function
Event
AWS Lambda
Event
Function
Invocation
Lambda API Call
AWS Lambda Functions
Asynchronous Invocations

27. ContextContextResource
ContextContextResource
Context
Function
Event
AWS Lambda Managed by AWS
Not managed
by AWS
Result
(Optional)
Function
Invocation
Resources can
be files, records
in a DB, etc.
Lambda API Call
Functions can Modify Resources

28. Events
(Context)
Events
(Context)
Generated
by AWS
Not generated
by AWS
ContextContextResource
ContextContextResource
Context
Function
Event
AWS Lambda Managed by AWS
Not managed
by AWS
Result
(Optional)
Function
Invocation
Lambda API Call
Resources can Generate more Events

29. Events
(Context)
Events
(Context)
Generated
by AWS
Not generated
by AWS
ContextContextResource
ContextContextResource
AWS Lambda Managed by AWS
Not managed
by AWS
Direct Use
of Resource
For example,
a file is uploaded
or something is written
in a database
AWS Lambda
Function 2
Function 3
Function 1
Events can Trigger more Functions

30. Sample Event-Driven Serverless
Media-Sharing Application

31. Client
Application
Event-driven
Backend
User

32. Client
Application
Get Content
Index
Get Content
Upload Content
with Metadata
Update Content
Metadata
Get Content
Metadata
User

33. Client
Application
Get Content
Index
Get Content
Upload Content
with Metadata
Update Content
Metadata
Get Content
Metadata
AWS Lambda
User

34. Client
Application
Get Content
Index
Get Content
Upload Content
with Metadata
Update Content
Metadata
Get Content
Metadata
Files
(Multimedia)
Database
AWS Lambda
User
Resources

35. Client
Application
Get Content
Index
Get Content
and Thumbnails
Upload Content
with Metadata
Update Content
Metadata
Get Content
Metadata
Files
(Multimedia)
Database
Build
Thumbnails
Update
Content Index
Extract
and Update
Metadata
Event:
new or
updated
file
Event:
new or updated
content metadata
AWS Lambda
User
Resources

36. Get Content
Index
Get Content
and Thumbnails
Upload Content
with Metadata
Update Content
Metadata
Get Content
Metadata
Files
(Multimedia)
Database
Build
Thumbnails
Update
Content Index
Extract
and Update
Metadata
User Mobile
App

37. Get Content
Index
Get Content
and Thumbnails
Upload Content
with Metadata
Update Content
Metadata
Get Content
Metadata
Files
(Multimedia)
Database
Build
Thumbnails
Update
Content Index
Extract
and Update
Metadata
User
Web Browsers
(JavaScript)

38. Calling Functions
from the Client

39. Client
Application
AWS Lambda
Function
AWS Lambda
Invoke API
User
Calling Lambda Functions Directly

40. Client
Application
AWS Lambda
Function
AWS Lambda
Invoke API
Get Temporary
AWS Credentials Amazon
Cognito
User
Getting AWS Credentials from Amazon Cognito

41. Client
Application
AWS Lambda
Function
Amazon
Cognito
Amazon
API Gateway
Get Temporary
AWS Credentials
Web API Modeling,
Caching, Throttling,
Logging, CDN, etc.
User
Exposing Functions as Web API

42. Client
Application
AWS Lambda
Function
Amazon
API Gateway
Web API Modeling,
Caching, Throttling,
Logging, CDN, etc.
User
Exposing Functions as Public Web API

43. https://some.domain/stage/resource1/resource2/…/resourceN
GET
POST
PUT
DELETE
HEAD
PATCH
OPTIONS
Unique domain
that you can
customize
API stage, for example
prod, test, dev, or v0, v1, …
Resources as part of the URL
HTTP verb
used when
accessing the URL
function1
function2
function3
function1
function2
function3
function1
Function
to execute
Web API to Lambda Functions Integration

44. Web API to Lambda Functions Mapping
Resource + HTTP Verb ➔ Method

45. Web API to Lambda Functions Mapping
Resource + HTTP Verb ➔ Method
/books + GET ➔ GetAllBooks

46. Web API to Lambda Functions Mapping
Resource + HTTP Verb ➔ Method
/books + GET ➔ GetAllBooks
/books + POST ➔ CreateNewBook

47. Web API to Lambda Functions Mapping
Resource + HTTP Verb ➔ Method
/books + GET ➔ GetAllBooks
/books + POST ➔ CreateNewBook
/books/{id} + GET ➔ GetBookById
/books/{id} + PUT ➔ CreateOrUpdateBookById
/books/{id} + DELETE ➔ DeleteBookById

48. Best Practices

50. Distributed Systems

51. Distribute the Logic
React to Changes

52. Preserve
Independent Deployment
Of Functions

53. <demo>
...
</demo>

54. Building Event-Driven
Serverless Applications
Danilo Poccia
Technical Evangelist
@danilop
danilop