What is delta-server?

Delta Server helps app developers push small updates to a React Native mobile app without waiting for Apple or Google to approve a new version in their app stores. Instead of sending the whole app bundle again every time something changes, it works out exactly what changed since the last release and sends only that small difference, called a delta patch, down to each phone. This project is the backend piece of a bigger system. It stores and organizes every release of your app's code, generates those small patches, and serves them out through a content delivery network so millions of devices can grab them quickly. It also lets a team target updates to specific app versions, roll updates out gradually to a portion of users first, and roll back instantly if a release turns out to be broken. It keeps a record of every release, deployment, and rollout so a team can see the full history of what shipped and when. Under the hood it runs on Amazon Web Services. The update logic lives in small serverless functions called Lambdas, written in TypeScript. App data and release records are stored in DynamoDB, a database service from AWS. The actual code bundles and patch files sit in S3 storage, and CloudFront, Amazon's content delivery network, sits in front of everything to make downloads fast worldwide. Requests come in through API Gateway, which routes them to the right Lambda function. Setting this up is not a quick task. It requires an AWS account, the AWS command line tools, and Amazon's SAM tool for deploying cloud infrastructure as code, plus filling in several configuration files with values specific to your own AWS account. It is meant for a company or team that wants to run their own private version of an app update service rather than depending on a third-party OTA provider. It works alongside two companion projects, a command line tool for managing releases and a client library that goes inside the React Native app itself. This is aimed at mobile engineering teams who are comfortable with cloud infrastructure, not at beginners or non-technical users.