Example

This example is designed for a concept mobile application called Skip the Line, which allows user to pre-order takeaway coffee while they are in transit. Just as the train pulls into the station, the user can order a coffee and pick it up on the way past the coffee shop.

In this example Amazon EventBridge rules that are used to invoke Lambda functions when events are added to the EventBus. The EventBus sits behind a HTTP API endpoint, the client application pass a request to the api endpoint which includes the attribute 'eventtype':[new_order]. The EventBus matches the attribute to a rule which then triggers a Lambda target. The advantage to using this pattern is that the API Gateway is configured with a single API endpoint for the client. The EventBridge handles routing of the request to the Lambda functions using rules. The EventBus rules can be easily created and modified, which simplifies the process of building event-driven architectures

The Amazon DynamoDB table is partitioned on an accountid attribute and also includes a sort key on the vendorid attribute, together they form the primary key. The example also demonstrates using Python to put, update and delete items in Amazon DynamoDB.

Setup

You will need to download and install Node.js before you can start using the AWS Cloud Development Kit.

This example is developed using the AWS CDK and Typescript, so you will need to install both Typescript and the CDK using the following commands

npm install -g typescript
npm install -g aws-cdk@latest

Since this CDK project uses 'Assests', you might need to run the following command to provision resources the AWS CDK will need to perform the deployment.

cdk bootstrap

The testing scripts can be executed using Jupyter Notebook. There are a few methods for installing Jupyter Notebooks. These instructions will help you get to started with JupyterLab installation.

You can also install Jupyter Notebooks as part of Anaconda installation.

To download this example, you will need to install Git. After installing git follow these instructions to learn how to clone the repository.

After the repository has been cloned set the command prompt path to the cloned directory and run the following command to install the project dependencies.

npm install

cdk synth executes the application which translates the Typescript code into an AWS CloudFormation template.

cdk synth

After the synth command has generated the template use the cdk deploy command to deploy the template to AWS CloudFormation and build the stack. You will be prompted to confirm the deployment with y/n.

cdk deploy

Run the Example

Open the Jupyter Notebook in the jupyter_notebook directory follow the instructions.

Cleanup

From the command prompt execute the following command: cdk destroy

Deployed Resources

Identifier	Service	Type
EventSourcingEventbridgeS-aws generated name	Lambda	Function
EventSourcingEventbridgeS-aws generated name	IAM	Role
event_sourcing_eventbridge	DynamoDB	Table
event_sourcing_eventbridge_api_role	IAM	Role
/demo/event_sourcing_eventbridge	Logs	LogGroup
event_sourcing_eventbridge	event_sourcing_eventbridge_logger	Events
event_sourcing_eventbridge_put_item	Lambda	Function
event_sourcing_eventbridge_update_item	Lambda	Function
event_sourcing_eventbridge_delete_item	Lambda	Function
event_sourcing_eventbridge_lambda_put	IAM	Role
event_sourcing_eventbridge_lambda_update	IAM	Role
event_sourcing_eventbridge_lambda_delete	IAM	Role
event_sourcing_eventbridge	event_sourcing_eventbridge_new_order	Events
event_sourcing_eventbridge	event_sourcing_eventbridge_update_order	Events
event_sourcing_eventbridge	event_sourcing_eventbridge_delete_order	Events