AWS Lambda in C#

© 2016, Amazon Web Services, Inc. or its Affiliates. All rights reserved.
John Chang (張書源)
Technology Evangelist
January, 2017
Serverless Development with
C# and AWS Lambda

What to Expect from the Session
• Brief Introduction to AWS Lambda
• Why .NET Core
• New .NET Core Lambda tooling
• Lots of exciting demos!

AWS Lambda Crash Course
• Compute part of the AWS serverless architecture
• Zero administration
• Event-driven scaling
• Never pay for idle time
• Upload your code and go

Why .NET Core?
• Performance
• Modularized design
• Low memory usage
• Open Source
• Built and validated for Amazon Linux
• Allow AWS to respond to security issues
• Cross Platform
• Develop on any platform and run on Amazon Linux

.NET Core Development
• .NET Core 1.0
• https://www.microsoft.com/net/download/core
• Visual Studio 2015 Update 3
• Visual Studio 2015 Tools (Preview 2)
• Target framework netcoreapp1.0
• Package with .NET Core CLI “dotnet publish”
• Upload as a zip file

Declaring Lambda Functions
• Static or instance methods
• Must have a default constructor for instance methods
• Can take 0 or 1 input parameters
public void FunctionHandler()
public void FunctionHandler(S3Event evnt)
public string FunctionHandler(S3Event evnt, ILambdaContext context)
• Optional ILambdaContext parameter

• async methods must return a Task or Task<T>
Declaring Lambda Functions
public async Task FunctionHandler<T>(T obj, ILambdaContext context)
public void FunctionHandler<T>(T obj, ILambdaContext context)
• No generic methods
public async Task FunctionHandler(S3Event evnt, ILambdaContext context) // return void
public async Task<MyType> FunctionHandler(S3Event evnt, ILambdaContext context)

Invoking from AWS Lambda Event Sources
• Function executes in response to events in AWS
services
• A few of the supported services
• Amazon S3
• Amazon DynamoDB
• Amazon Kinesis
• ….
• Scheduled Events

Invoking with the AWS SDKs
• Invoke methods using any SDK
• Great for mobile apps
• Manage credentials with Amazon Cognito
var client = new AmazonLambdaClient(cognitoCredentials, RegionEndpoint.USWest2);
var request = new InvokeRequest
{
FunctionName = "ProcessGameScore",
Payload = gameStats
};
InvokeResponse response = await client.InvokeAsync(request);

Invoking from Amazon API Gateway
• Frontend of the AWS Serverless architecture
• Expose Lambda functions as HTTP API
• Manages authentication, versioning, monitoring and
more

Demo:
Responding to AWS Events

Recap
• Created a new Lambda project in Visual Studio
• Learned how serialization works
• Learned about the handler format
• assemblyname::namespaced-classname::methodname
• Published from Visual Studio
• Configured AWS event source
• Invoked the Lambda function from Visual Studio

Demo:
Cross Platform: Command Line

Yeoman Project Generators
• Project generator ecosystem
• Installable via npm:
• Node.js dependency
• npm install –g yo
• AWS Lambda generators
• npm install –g generator-aws-lambda-dotnet
• yo aws-lambda-dotnet

Recap Cross-Platform Demo
• Created a project with Yeoman
• npm install –g yo generator-aws-lambda-dotnet
• yo aws-lambda-dotnet
• Develop with any editor
• Command line deployment with the .NET CLI and
Amazon.Lambda.Tools NuGet package
• dotnet lambda <command> <args>
• In preview

Demo Application Architecture
internet
GetBlogs()
GetBlog()
AddBlog()
RemoveBlog()
API Gateway
AWS Lambda
Amazon DynamoDB
AWS CloudFormation Stack

Our Serverless Application Deployment
Visual Studio
Project
Amazon S3
AWS CloudFormation
App bundle
(.zip)
Serverless
template
2: Request stack
…other resources
Lambda Functions
…other resources
API Gateway
4: Stack launched
3: Fetch template

Recap Serverless Application
• Created an AWS Serverless application
• Learned about the serverless.template file
• Exposed Lambda functions as a HTTP API
• Deployed using AWS CloudFormation

ASP.NET Core and Web API
• ASP.NET Core is the web framework for .NET Core
• Includes framework for building Web API applications
• Define API controllers to respond to requests
• Maps request data to function parameters
[Route("api/[controller]")]
public class ValuesController : Controller
{
// PUT api/values/5
[HttpPut("{id}")]
public void Put(int id, [FromBody]string value)
{
...
}
...

How can we use ASP.NET Core in Lambda?
• Amazon API Gateway Proxy Integration
• Forwards all requests to a Lambda Function
• Lambda Function
• Converts how requests and responses are represented
between API Gateway and ASP.NET Core
• Implemented by Amazon.Lambda.AspNetCoreServer
NuGet package
• Currently in preview

ASP.NET Core Web API Architecture
IIS /
Nginx
Kestrel
ASP.NET
Core
Hosting
User’s Web API
Controllers
Internet

ASP.NET Core Architecture on Lambda
API
Gateway
Lambda
ASP.NET
Core
Hosting
User’s Web API
Controllers
Internet

Recap ASP.NET Core Web API Demo
• Used existing ASP.NET Core framework
• No change to controller code
• Used API Gateway Proxy Integration to forward all
requests
• Lambda function translates between API Gateway and
ASP.NET Core
• Amazon.Lambda.AspNetCoreServer NuGet Package
• In preview
• Looked at the handler source in GitHub

Useful Links
• AWS Toolkit for Visual Studio
• https://aws.amazon.com/visualstudio/
• AWS Lambda .NET GitHub
• https://github.com/aws/aws-lambda-dotnet
• AWS .NET Developer Blog
• https://aws.amazon.com/blogs/developer/category/net/
• AWS Lambda Developer Guide
• http://docs.aws.amazon.com/lambda/latest/dg/welcome.html
• AWS Toolkit for Visual Studio Guide
• http://docs.aws.amazon.com/toolkit-for-visual-
studio/latest/user-guide/welcome.html

Other Related Sessions
CMP211 - Getting Started with Serverless Architectures
SRV202 – What’s New with AWS Lambda
DEV301 - Amazon CloudWatch Logs and AWS Lambda: A Match Made in
Heaven
MBL306 - Serverless Authentication and Authorization: Identity Management
for Serverless Architectures
SVR311 - The State of Serverless Computing

Remember to complete
your evaluations!

AWS Lambda in C#

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