The Fabric Gateway is a core component of a Fabric blockchain network and coordinates the actions required to submit transactions and query ledger state on behalf of client applications. By using the Gateway, client applications only need to connect to a single endpoint in the Fabric network.

The Gateway SDKs implement the Fabric programming model as described in the Developing Applications chapter of the Fabric documentation.

The Gateway server is a standalone process (written in Go) and exposes a simple gRPC interface to client applications. The server manages the lifecycle of transaction invocation on behalf of the client, minimising the network traffic passing between the client and the blockchain network as well as minimising the number of network ports that need to be opened.

A prebuilt docker image is available for the Gateway server.

Three SDKs are available to support the development of client applications that interact with the Fabric network via the Gateway.

The Go SDK provides a high-level API for client applications written in Go.

Read the quickstart guide for more details.

The Node SDK provides a high-level API for client applications written in Javascript or Typescript.

Read the quickstart guide for more details.

The Java SDK provides a high-level API for client applications written in Java.

Read the quickstart guide for more details.

This repo comprises the Gateway server (written in Go) and three SDKs (written in Go, Typescript and Java). In order to build these components, the following needs to be installed and available in the PATH:

• Go (v1.14)
• Node (optional for Node SDK)
• Typescript (optional for Node SDK)
• Java 11 (optional for Java SDK)
• Docker
• Protobuf compiler (https://developers.google.com/protocol-buffers/docs/downloads)
• Some Go tools:
  • GO111MODULE=on go get github.com/cucumber/godog/cmd/godog@v0.10.0
  • go get -u golang.org/x/lint/golint
  • go get -u golang.org/x/tools/cmd/goimports
  • go get google.golang.org/grpc google.golang.org/protobuf/cmd/protoc-gen-go google.golang.org/grpc/cmd/protoc-gen-go-grpc

The following Makefile targets are available

• make build-go - compile the gateway server executable
• make docker - create a docker image containing the gateway server
• make unit-test-go - run unit tests for the gateway server and Go SDK
• make unit-test-node - run unit tests for the Node SDK
• make unit-test-java - run unit tests for the Java SDK
• make unit-test - run unit tests for the gateway server and all three SDKs
• make scenario-test-go - run the scenario (end to end integration) tests for Go SDK
• make scenario-test-node - run the scenario tests for Node SDK
• make scenario-test-java - run the scenario tests for Java SDK
• make scenario-test - run the scenario tests for all SDKs
• make test - run all unit and scenario tests

The scenario tests create a Fabric network comprising two orgs (one peer in each org) and a single gateway within a set of docker containers. The clients connect to the gateway to submit transactions and query the ledger state.

The tests are defined as feature files using the Cucumber BDD framework. The same set of feature files is used across all three SDKs to ensure consistency of behaviour.