Android Kotlin + Apollo Client

This guide assumes a secure backend API has been setup for the client applications to acquire limited access tokens. It is also assumed that an appropriate authentication and authorisation method has been put in place for communication between the Android app and the secure backend API.

It is recommended to use Apollo Kotlin package as the client library for communicating with the Verified Orchestration GraphQL API. In particular, the following tutorials from Apollo are helpful with setting up the Apollo client in the Android Kotlin app.

• Build a project with Apollo
• Subscriptions

For subscribing to events in Verified Orchestration platform, it is recommended to use WebSocket protocol with graphql-ws subprotocol [doc].

It is necessary to pass the limited access token obtained from the secure backend API to the Verified Orchestration platform for all GraphQL operations and subscriptions. These two tutorials from Apollo demonstrate how to pass an access token as the authorisation header for the GraphQL operations and subscriptions.

• Authenticate your operations
• Providing authorisation tokens for subscriptions

Once the ApolloClient has been configured appropriately, issuance and presentation operations can be implemented in the app using GraphQL operations and subscriptions.