refactor(fabric): add discovery client

This commit moves the discovery client imported from fabric into a local
package, including tests.

Signed-off-by: Marcus Brandenburger <bur@zurich.ibm.com>

Author: mbrandenburger

platform/fabric/core/generic/chaincode/discovery.go

@@ -15,12 +15,12 @@ import (
 
 	"github.com/hyperledger-labs/fabric-smart-client/pkg/utils/errors"
 	"github.com/hyperledger-labs/fabric-smart-client/platform/common/utils/cache"
+	"github.com/hyperledger-labs/fabric-smart-client/platform/fabric/core/generic/discovery"
 	peer2 "github.com/hyperledger-labs/fabric-smart-client/platform/fabric/core/generic/services"
 	"github.com/hyperledger-labs/fabric-smart-client/platform/fabric/driver"
 	"github.com/hyperledger-labs/fabric-smart-client/platform/view/view"
 	discovery2 "github.com/hyperledger/fabric-protos-go-apiv2/discovery"
 	"github.com/hyperledger/fabric-protos-go-apiv2/peer"
-	discovery "github.com/hyperledger/fabric/discovery/client"
 )
 
 const (

platform/fabric/core/generic/discovery/api.go

@@ -0,0 +1,68 @@
+/*
+Copyright IBM Corp. All Rights Reserved.
+
+SPDX-License-Identifier: Apache-2.0
+*/
+
+package discovery
+
+import (
+	"github.com/hyperledger-labs/fabric-smart-client/pkg/utils/errors"
+	"github.com/hyperledger/fabric-protos-go-apiv2/discovery"
+	"github.com/hyperledger/fabric-protos-go-apiv2/peer"
+	"google.golang.org/grpc"
+)
+
+// ErrNotFound defines an error that means that an element wasn't found
+var ErrNotFound = errors.New("not found")
+
+// Signer signs a message and returns the signature and nil,
+// or nil and error on failure
+type Signer func(msg []byte) ([]byte, error)
+
+// Dialer connects to the server
+type Dialer func() (*grpc.ClientConn, error)
+
+// Response aggregates several responses from the discovery service
+type Response interface {
+	// ForChannel returns a ChannelResponse in the context of a given channel
+	ForChannel(string) ChannelResponse
+}
+
+// ChannelResponse aggregates responses for a given channel
+type ChannelResponse interface {
+	// Config returns a response for a config query, or error if something went wrong
+	Config() (*discovery.ConfigResult, error)
+
+	// Peers returns a response for a peer membership query, or error if something went wrong
+	Peers(invocationChain ...*peer.ChaincodeCall) ([]*Peer, error)
+
+	// Endorsers returns the response for an endorser query for a given
+	// chaincode in a given channel context, or error if something went wrong.
+	// The method returns a random set of endorsers, such that signatures from all of them
+	// combined, satisfy the endorsement policy.
+	// The selection is based on the given selection hints:
+	// Filter: Filters and sorts the endorsers
+	// The given InvocationChain specifies the chaincode calls (along with collections)
+	// that the client passed during the construction of the request
+	Endorsers(invocationChain InvocationChain, f Filter) (Endorsers, error)
+}
+
+// LocalResponse aggregates responses for a channel-less scope
+type LocalResponse interface {
+	// Peers returns a response for a local peer membership query, or error if something went wrong
+	Peers() ([]*Peer, error)
+}
+
+// Endorsers defines a set of peers that are sufficient
+// for satisfying some chaincode's endorsement policy
+type Endorsers []*Peer
+
+// Peer aggregates identity, membership and channel-scoped information
+// of a certain peer.
+type Peer struct {
+	MSPID            string
+	AliveMessage     *SignedGossipMessage
+	StateInfoMessage *SignedGossipMessage
+	Identity         []byte
+}