I have been searching around, looking for information or tutorials to integrate the SmartyStreets API with an application I wish to deploy to AWS. I have created a service that creates entries of addresses in a DynamoDB table, but geolocation data is missing. What I wish to do is use Lambda, and or the AWS API Gateway to watch for new documents, geocode, and update the documents in DynamoDB. I am not having much luck and any help would be appreciated.
You need to enable a trigger on your DynamoDB table to push new/updated records to a Lambda function. Your Lambda function could take the DynamoDB record, query the third-party API for geolocation data, and then update the record.
See this walkthrough for creating a trigger on your DynamoDB table: http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Streams.Lambda.Walkthrough.html
If you have specific questions about how to create the Lambda function or how to query the third-party API from within Lambda, that is probably best asked as a separate question on this site.