Update README.md

Author: markusklems

README.md

@@ -1,2 +1,34 @@
-# aws-lambda-java-example
-A simple Java Lambda based server-less application that implements a reimbursement use case, with AWS Lambda, AWS SES, and AWS DynamoDB
+# AWS Lambda Java Example
+
+A simple Java Lambda based server-less application that implements a reimbursement use case, with AWS Lambda, AWS API Gateway, AWS SES, and AWS DynamoDB. Set up the project with Eclipse and AWS Toolkit plugin.
+
+## Getting Started
+### IDE Setup
+1. Open Eclipse
+2. Install the AWS Toolkit for Eclipse and set up your AWS access key id and secret access key: http://docs.aws.amazon.com/AWSToolkitEclipse/latest/ug/tke_setup_install.html
+3. Import project LambdaForm: Right click on the Package Explorer > Import > General > Existing Projects into Workspace. Do the same for LambdaSendMail and LambdaApproval.
+4. Sign up for AWS Lambda, API Gateway, DynamoDB, and SES (if you have not done so, yet).
+
+### Upload Lambda Functions
+5. Right click on the LambdaForm project folder > Amazon Web Services > Upload Function to AWS Lambda > Follow the steps in the wizard and create a new Lambda Function.
+6. Upload the Lambda Functions of the other two projects LambdaSendMail and LambdaApproval.
+7. Give the Lambda Functions an IAM role that allows access to DynamoDB and SES.
+
+### AWS Services setup
+8. Set up a DynamoDB table named 'lambda-reimbursment' with the Hash Key 'employee_id' of type String. In the example, the EU-WEST-1 region (Ireland) is chosen.
+9. In the AWS dashboard, go to Lambda > LambdaSendMail > Event source. Add an event source of type DynamoDB (table: lambda-reimbursment) with default settings.
+10. Do the same as in step 5 for LambdaApproval.
+11. In the AWS dashboard, go to API Gateway and create a new API that points at the LambdaApproval Function. Create a Resource "reimbursment" and a GET method. Click on "Method Request" and add a query string parameter "id". Click on "Integration Request" and add a Mapping Template with content type "application/json" and Template:
+```
+{
+    "employee_id" : "$input.params('id')"
+}
+```
+Deploy the API.
+
+### Run Lambda Functions
+12. Right click on the LambdaForm project folder > Amazon Web Services > Run Function on AWS Lambda > Enter a JSON object like this one:
+```{"employee_id":"1", "employee_name":"John Doh", "expense_type":"travel","amount": "456.75" }```
+13. If the Lambda Function completes successfully, a new entry will be added to the DynamoDB table lambda-reimbursment that you created in step 8.
+14. LambdaSendMail gets triggered by the DynamoDB stream (pull model) and sends an e-mail with the info that has been added to the table.
+15. If you have received the e-mail and click on the approval URL in the e-mail body, the LambdaApproval Function will be called and add an "approved" column entry to DynamoDB.