To connect to Blockchain network’s Peer(e.g. peer0.org2.example.com:7051) where chain code deployed, we usually use below three packages :
1. “github.com/hyperledger/fabric-sdk-go/pkg/fabsdk”
returns an instance of FabricSDK for given configuration file
var Sdk *fabsdk.FabricSDK
https://github.com/hyperledger/fabric-sdk-go/blob/cb4ad138c14fd98039c56ab6301e665254a930bc/doc.go
2. “github.com/hyperledger/fabric-sdk-go/pkg/client/channel”
Get the Channel Client Context by passing the reference of the instance of Fabric SDK crated from previous step
var Client *channel.Client
Refer for Query and Execute
https://github.com/hyperledger/fabric-sdk-go/blob/master/pkg/client/channel/chclient.go
// If calling Query
response, err := instance.Client.Query(channel.Request{ChaincodeID: request.ChaincodeId, Fcn: request.Fn, Args: argsAsBytes})
if err != nil {
utils.Info(“Failed to query cc: %s”, err)
}
// If calling Invoke
response, err := instance.Client.Execute(channel.Request{ChaincodeID: request.ChaincodeId, Fcn: request.Fn, Args: argsAsBytes})
if err != nil {
utils.Info(“Failed to invoke cc: %s\n”, err)
}
3. “github.com/hyperledger/fabric-sdk-go/pkg/client/ledger”
If needed ledger Client then go to this package and then pass Channel Context.
var LedgerClient *ledger.Client
References : (How the combination of 1,2,3 have been used to access the deployed chain code in network)
func queryCC(t *testing.T, client *channel.Client, targetEndpoints …string) []byte {
response, err := client.Query(channel.Request{ChaincodeID: ccID, Fcn: “invoke”, Args: integration.ExampleCCDefaultQueryArgs()},
channel.WithRetry(retry.DefaultChannelOpts),
channel.WithTargetEndpoints(targetEndpoints…),
)
if err != nil {
t.Fatalf(“Failed to query funds: %s”, err)
}
return response.Payload
}
https://github.com/hyperledger/fabric-sdk-go/blob/master/pkg/client/ledger/ledger.go
Also refer :
https://www.skcript.com/svr/setting-hyperledger-fabric-network-multiple-chaincodes-channels/
Sumit Arora 