FABG-943 Enhance documentation and add examples (hyperledger#75)

Add parameter/return details to the GoDoc comments in pkg/gateway
Add usage examples to the GoDoc documentation
Add reference to pkg/gateway in doc.go and README.md
Remove unused option to disable discovery

Signed-off-by: andrew-coleman <[email protected]>

README.md

@@ -26,6 +26,8 @@ SDK documentation can be viewed at [GoDoc](https://godoc.org/github.com/hyperled
 
 The packages intended for end developer usage are within the pkg/client folder along with the main SDK package (pkg/fabsdk).
 
+If you wish to use the Fabric 'Gateway' programming model, then the API is in the pkg/gateway folder.
+
 ### Examples
 
 - [E2E Test](test/integration/e2e/end_to_end.go): Basic example that uses SDK to query and execute transaction

doc.go

@@ -37,4 +37,14 @@ SPDX-License-Identifier: Apache-2.0
 //         Note: you create a new client instance for each context you need.
 //      4) Use the funcs provided by each client to create your solution!
 //      5) Call fabsdk.Close() to release resources and caches.
+//
+// Support for Hyperledger Fabric programming model
+//
+// In order to support the 'Gateway' programming model, the following package is provided:
+//
+// pkg/gateway: Enables Go developers to build client applications using the Hyperledger
+// Fabric programming model as described in the 'Developing Applications' chapter of the Fabric
+// documentation.
+// Reference: https://godoc.org/github.com/hyperledger/fabric-sdk-go/pkg/gateway
+//
 package fabricsdk

pkg/gateway/contract.go

@@ -34,6 +34,12 @@ func (c *Contract) Name() string {
 // will be evaluated on the endorsing peers but the responses will not be sent to
 // the ordering service and hence will not be committed to the ledger.
 // This can be used for querying the world state.
+//  Parameters:
+//  name is the name of the transaction function to be invoked in the smart contract.
+//  args are the arguments to be sent to the transaction function.
+//
+//  Returns:
+//  The return value of the transaction function in the smart contract.
 func (c *Contract) EvaluateTransaction(name string, args ...string) ([]byte, error) {
 	txn, err := c.CreateTransaction(name)
 
@@ -47,6 +53,12 @@ func (c *Contract) EvaluateTransaction(name string, args ...string) ([]byte, err
 // SubmitTransaction will submit a transaction to the ledger. The transaction function 'name'
 // will be evaluated on the endorsing peers and then submitted to the ordering service
 // for committing to the ledger.
+//  Parameters:
+//  name is the name of the transaction function to be invoked in the smart contract.
+//  args are the arguments to be sent to the transaction function.
+//
+//  Returns:
+//  The return value of the transaction function in the smart contract.
 func (c *Contract) SubmitTransaction(name string, args ...string) ([]byte, error) {
 	txn, err := c.CreateTransaction(name)
 
@@ -61,8 +73,14 @@ func (c *Contract) SubmitTransaction(name string, args ...string) ([]byte, error
 // function implemented by this contract, and provides more control over
 // the transaction invocation using the optional arguments. A new transaction object must
 // be created for each transaction invocation.
-func (c *Contract) CreateTransaction(name string, args ...TransactionOption) (*Transaction, error) {
-	return newTransaction(name, c, args...)
+//  Parameters:
+//  name is the name of the transaction function to be invoked in the smart contract.
+//  opts are the options to be associated with the transaction.
+//
+//  Returns:
+//  A Transaction object for subsequent evaluation or submission.
+func (c *Contract) CreateTransaction(name string, opts ...TransactionOption) (*Transaction, error) {
+	return newTransaction(name, c, opts...)
 }
 
 // RegisterEvent registers for chaincode events. Unregister must be called when the registration is no longer needed.

pkg/gateway/contract_test.go

@@ -40,7 +40,6 @@ func TestSubmitTransaction(t *testing.T) {
 
 	gw := &Gateway{
 		options: &gatewayOptions{
-			Discovery: defaultDiscovery,
 			Timeout:   defaultTimeout,
 		},
 	}
@@ -69,7 +68,6 @@ func TestEvaluateTransaction(t *testing.T) {
 
 	gw := &Gateway{
 		options: &gatewayOptions{
-			Discovery: defaultDiscovery,
 			Timeout:   defaultTimeout,
 		},
 	}
@@ -98,7 +96,6 @@ func TestContractEvent(t *testing.T) {
 
 	gw := &Gateway{
 		options: &gatewayOptions{
-			Discovery: defaultDiscovery,
 			Timeout:   defaultTimeout,
 		},
 	}