We went from physical servers to the cloud and from running VMs in the cloud to running services in the cloud. And although the infrastructure got better and better, we still had to manage everything on our own. This is not the case anymore. Nowadays, we have the “serverless” services. There are many implementations to the idea. The most famous are the AWS Lambda and the Azure Functions. They provide a robust infrastructure for running your code in a scalable manner in a cloud environment. And since the solution is scalable, it is, by definition, a stateless solution. Does this mean that serverless is not a good solution? Is it just a cool gimmick? In this session, you are going to learn how we can manage state in a stateless, serverless environment on Azure, by utilizing Azure Durable Functions and how we can use the eco-system to build entire systems, completely serverless.

1. @AlexPshul
State in Stateless Serverless Functions
Alex Pshul
Embrace the serverless
@AlexPshul
alex@pshul.com
https://pshul.com
https://meetup.com/Code-Digest

2. @AlexPshul

3. @AlexPshul
Agenda
 Serverless Functions - Recap
 Pros
 Cons
 Functions Demo
 State in Stateless?
 Durable Functions
 Durable Entities
 Another Demo!
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Agenda

4. @AlexPshul
About Me
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Alex Pshul
 Architect, Microsoft Azure MVP, Consultant, Lecturer & Tech Freak
 More than 10 years of hands-on experience
 More than 30 projects
 Co-organizer of the Code.Digest Meetup
 https://www.meetup.com/Code-Digest/
 Talk to me about:

5. @AlexPshul
Serverless Functions
Pros. and Cons.
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6. @AlexPshul
Cost Effective
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7. @AlexPshul
Scalable
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8. @AlexPshul
Flexible
 Run native on cloud
 Or in a container
 Rich out-of-the-box solutions suite
 Http
 Message Bus
 Timer
 Easy to start
 Easy to deploy
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9. @AlexPshul
But…
 Latency
 Constant high load
 Premium functions (Azure)
 Provisioned Concurrency (AWS)
 Resource intensive computing
 Stateful server requests
 Long running tasks
 State
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10. @AlexPshul
But…
Stateful server requests
Long running tasks
State
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OR IS IT?

11. @AlexPshul
Demo
Functions App
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12. @AlexPshul
State in Stateless Functions
Durable Functions
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13. @AlexPshul
What is it?
 Azure Function Extension
 Supports in a variety of languages
 C#
 JavaScript/TypeScript
 Python
 F#
 PowerShell
 Uses a storage account for persistency
 Supports various scenarios
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14. @AlexPshul
Function Chaining
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const df = require("durable-functions");
module.exports = df.orchestrator(function*(context) {
try {
const x = yield context.df.callActivity("F1");
const y = yield context.df.callActivity("F2", x);
const z = yield context.df.callActivity("F3", y);
return yield context.df.callActivity("F4", z);
} catch (error) {
// Error handling or compensation goes here.
}
});

15. @AlexPshul
Fan Out - Fan In
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import azure.durable_functions as df
def orchestrator_function(context: df.DurableOrchestrationContext):
# Get a list of N work items to process in parallel.
work_batch = yield context.call_activity("F1", None)
parallel_tasks = [ context.call_activity("F2", b) for b in work_batch
]
outputs = yield context.task_all(parallel_tasks)
# Aggregate all N outputs and send the result to F3.
total = sum(outputs)
yield context.call_activity("F3", total)
main = df.Orchestrator.create(orchestrator_function)

16. @AlexPshul
Other Scenarios
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Async HTTP APIs Monitor
Human Interaction

17. @AlexPshul
Durable Entities
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 Allows to store data “in memory”
 Backed by Durable functions
 C#
 JavaScript/TypeScript
 Python
 Uses a storage account for persistency
 Can be accessed from different functions

18. @AlexPshul
Demo
Durable Entities
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19. @AlexPshul
Summary
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 Serverless
 Easy
 Scalable
 Supported by many languages
 C#
 JavaScript/TypeScript
 Python
 F# (No durable support)
 PowerShell (No durable support)
 State in stateless functions with Durable Functions
 Functions on steroid

20. Alex Pshul
@AlexPshul
https://www.pshul.com
alexp@codevalue.net
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