Meadowlark - Cloud Provider Parity Analysis

As mentioned in the Meadowlark Architecture, the Ed-Fi Alliance chose to develop Meadowlark on Amazon Web Services (AWS) simply because the development team needed to concentrate on one system while developing this proof-of-concept application. AWS was selected simply because they have the largest market share. However, the team stuck with a key principle: try to use only AWS managed services that have an analogous option on the other providers, which would make (relatively) easy to migrate from one platform to the other. This document reviews the services used and identifies the equivalent tools (or gaps) in Azure and in Google Cloud, with a bonus add-on of documenting equivalent services available on-premises.

Purpose	AWS Service	Azure	Google	On-Premises	Additional Notes
Load balancing and reverse proxy	API Gateway	Azure Application Gateway	Cloud Endpoints	NGiNX, among others
Serverless Application	AWS Lambda	Azure Functions	Google Cloud Functions	OpenFaas or Fn	The Meadowloark application is written in Typescript using the Serverless package, making it theoretically easy to reuse these components with any platform's serverless functions. Could consider refactoring to OpenFaas or Fn for one system that is cloud-agnostic (runs in Kubernetes and Docker, respectively).
Key-value data store and Change Data Capture	DynamoDB with DynamoDB Change Data Capture	CosmosDB in Cassandra API mode with CosmosDB Change Feed with Azure Functions	Firestore see note below about change streams	Apache Cassandra with Cassandra Triggers	The differences may be great enough that some tweaking of the storage model may be required. Switching to MongoDB may be a useful alternative, as it is available on all platforms: Amazon DocumentDB with Change Streams Azure CosmosDB has a MongoDB mode MongoDB Atlas running on any of the three MongoDB can also run on-premises, with Change Data Capture Handlers. Another option would be to switch to Cassandra for a single database platform available on all providers Amazon Keyspaces CosmosDB Astra DB from DataStax, running on any of the three Cassandra can also run on-premises
Search engine	Amazon OpenSearch	Elastic on Azure	Elastic on Google Cloud Platform	Either ElasticSearch or OpenSearch can run on-premises

Google Firestore might not have a direct equivalent of Change Data Capture... at least, the searching for this does not turn up functionality that is clearly the same as with the other products. However, perhaps one of these techniques is capable of writing out to a stream: Extend... with Cloud Functions or onSnapshot.