Use interface instead of @grpc/grpc-js Client class in public API

Since the gRPC Client is a concrete class, changes to private members can cause version-to-version type incompatibilities if the caller has a dependency on a different version of @grpc/grpc-js. Requiring an interface containing only public methods of the gRPC Client class avoids these issues, provided there are no breaking changes in the gRPC Client API.

Signed-off-by: Mark S. Lewis <mark_lewis@uk.ibm.com>

node/src/gateway.test.ts

@@ -31,7 +31,7 @@ describe('Gateway', () => {
         it('throws if no identity supplied', () => {
             const options = {
                 client,
-            } as ConnectOptions;
+            } as unknown as ConnectOptions;
             expect(() => connect(options)).toThrow();
         });
     });

node/src/gateway.ts

@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-import { CallOptions, Client } from '@grpc/grpc-js';
+import { CallOptions, ChannelInterface, ClientDuplexStream, ClientReadableStream, ClientUnaryCall, ClientWritableStream, Deadline, Metadata, requestCallback } from '@grpc/grpc-js';
 import { common, gateway, peer } from '@hyperledger/fabric-protos';
 import { ChaincodeEventsRequest, Commit, Proposal, Transaction } from '.';
 import { BlockAndPrivateDataEventsRequest, BlockAndPrivateDataEventsRequestImpl, BlockEventsRequest, BlockEventsRequestImpl, FilteredBlockEventsRequest, FilteredBlockEventsRequestImpl } from './blockeventsrequest';
@@ -19,6 +19,27 @@ import { ProposalImpl } from './proposal';
 import { SigningIdentity } from './signingidentity';
 import { TransactionImpl } from './transaction';
 
+/**
+ * Interface describing the public API of the gRPC Client class.
+ */
+export interface GrpcClient {
+    close(): void;
+    getChannel(): ChannelInterface;
+    waitForReady(deadline: Deadline, callback: (error?: Error) => void): void;
+    makeUnaryRequest<RequestType, ResponseType>(method: string, serialize: (value: RequestType) => Buffer, deserialize: (value: Buffer) => ResponseType, argument: RequestType, metadata: Metadata, options: CallOptions, callback: requestCallback<ResponseType>): ClientUnaryCall;
+    makeUnaryRequest<RequestType, ResponseType>(method: string, serialize: (value: RequestType) => Buffer, deserialize: (value: Buffer) => ResponseType, argument: RequestType, metadata: Metadata, callback: requestCallback<ResponseType>): ClientUnaryCall;
+    makeUnaryRequest<RequestType, ResponseType>(method: string, serialize: (value: RequestType) => Buffer, deserialize: (value: Buffer) => ResponseType, argument: RequestType, options: CallOptions, callback: requestCallback<ResponseType>): ClientUnaryCall;
+    makeUnaryRequest<RequestType, ResponseType>(method: string, serialize: (value: RequestType) => Buffer, deserialize: (value: Buffer) => ResponseType, argument: RequestType, callback: requestCallback<ResponseType>): ClientUnaryCall;
+    makeClientStreamRequest<RequestType, ResponseType>(method: string, serialize: (value: RequestType) => Buffer, deserialize: (value: Buffer) => ResponseType, metadata: Metadata, options: CallOptions, callback: requestCallback<ResponseType>): ClientWritableStream<RequestType>;
+    makeClientStreamRequest<RequestType, ResponseType>(method: string, serialize: (value: RequestType) => Buffer, deserialize: (value: Buffer) => ResponseType, metadata: Metadata, callback: requestCallback<ResponseType>): ClientWritableStream<RequestType>;
+    makeClientStreamRequest<RequestType, ResponseType>(method: string, serialize: (value: RequestType) => Buffer, deserialize: (value: Buffer) => ResponseType, options: CallOptions, callback: requestCallback<ResponseType>): ClientWritableStream<RequestType>;
+    makeClientStreamRequest<RequestType, ResponseType>(method: string, serialize: (value: RequestType) => Buffer, deserialize: (value: Buffer) => ResponseType, callback: requestCallback<ResponseType>): ClientWritableStream<RequestType>;
+    makeServerStreamRequest<RequestType, ResponseType>(method: string, serialize: (value: RequestType) => Buffer, deserialize: (value: Buffer) => ResponseType, argument: RequestType, metadata: Metadata, options?: CallOptions): ClientReadableStream<ResponseType>;
+    makeServerStreamRequest<RequestType, ResponseType>(method: string, serialize: (value: RequestType) => Buffer, deserialize: (value: Buffer) => ResponseType, argument: RequestType, options?: CallOptions): ClientReadableStream<ResponseType>;
+    makeBidiStreamRequest<RequestType, ResponseType>(method: string, serialize: (value: RequestType) => Buffer, deserialize: (value: Buffer) => ResponseType, metadata: Metadata, options?: CallOptions): ClientDuplexStream<RequestType, ResponseType>;
+    makeBidiStreamRequest<RequestType, ResponseType>(method: string, serialize: (value: RequestType) => Buffer, deserialize: (value: Buffer) => ResponseType, options?: CallOptions): ClientDuplexStream<RequestType, ResponseType>;
+}
+
 /**
  * Options used when connecting to a Fabric Gateway.
  * @example
@@ -47,7 +68,7 @@ export interface ConnectOptions {
      * A gRPC client connection to a Fabric Gateway. This should be shared by all gateway instances connecting to the
      * same Fabric Gateway. The client connection will not be closed when the gateway is closed.
      */
-    client: Client;
+    client: GrpcClient;
 
     /**
      * Client identity used by the gateway.

node/src/index.ts

@@ -18,7 +18,7 @@ export { CommitStatusError } from './commitstatuserror';
 export { Contract } from './contract';
 export { EndorseError } from './endorseerror';
 export { EventsOptions } from './eventsbuilder';
-export { connect, ConnectOptions, Gateway } from './gateway';
+export { connect, ConnectOptions, Gateway, GrpcClient } from './gateway';
 export { ErrorDetail, GatewayError } from './gatewayerror';
 export { Hash } from './hash/hash';
 export * as hash from './hash/hashes';