RESTful API Demo

Updated on 2023-03-07 GMT+08:00

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BCS provides RESTful APIs to simplify the usage of blockchains. You only need to develop applications that support RESTful APIs to access blockchains without the need to learn Hyperledger Fabric SDKs for Golang, Java, and Node.js. This demo uses a Golang client to show how RESTful APIs are used to invoke a chaincode.

NOTE:

This is a demo only and is not for actual use.

Creating a BCS Instance

Log in to the BCS console.
Click Create BCS Instance in the upper right corner of the page.

Configure basic information about the BCS instance by referring to Table 1.

NOTICE:

To ensure that the demo runs properly, set the parameters as described in the following table.

**Table 1** Basic settings
Parameter	Setting
Region	Retain the default value.
Enterprise Project	Select default.
Instance Name	Enter demo.
Edition	Professional
Blockchain Type	Select Private.
Enhanced Hyperledger Fabric Version	v2.2
Consensus Mechanism	Raft(CFT)
Resource Access Initial Password	Enter a password.
Confirm Password	Confirm the password.

Click Next: Configure Resources. Table 2 describes the resource parameters.

**Table 2** Resource configurations
Parameter	Example
Environment Resources	Select Custom.
Cluster	Select Create a new CCE cluster.
AZ	Select an AZ.
ECS Specifications	Select the flavor for 4 vCPUs \| 8 GB.
ECS Quantity	Enter 1.
High Availability	Select No.
VPC	Select Automatically create VPC.
Subnet	Select Automatically create subnet.
ECS Login Method	Select Password.
Password of Root User	If you do not enter a password here, the previously specified resource access initial password will be used.
Confirm Password	-
Use EIP of a CCE Node	Select Yes.
EIP Billed By	Retain the default value.
EIP Bandwidth	Set it to 5 Mbit/s.

Click Next: Configure Blockchain. Table 3 describes the blockchain parameters.

**Table 3** Blockchain configurations
Parameter	Example
Blockchain Configuration	Select Custom.
Blockchain Mgmt. Initial Password	If you do not enter a password here, the previously specified resource access initial password will be used.
Confirm Password	-
Volume Type	Select SFS Turbo.
Storage Capacity of Peer Organization (GB)	Retain the default value.
Ledger Storage	Select File database (GoLevelDB).
Peer Organization	A peer organization named organization has been automatically created. Change the peer quantity to 1.
Channel Configuration	The organization organization has been added to the channel automatically. Retain this default setting.
Orderer Quantity	Retain the default value.
Security Mechanism	Select ECDSA. NOTICE: Only ECDSA can be selected.
Configure Block Generation	Select No.
Enable Support for RESTful API	Select Yes. If you select No, you can enable support for RESTful APIs later by performing the following steps: In the navigation pane on the left, choose Add-on Management. On the Add-on Repository tab page, hover the mouse pointer over the baas-restapi card. Click Install and select the created BCS instance.

Click Next: Confirm.
Confirm the configurations and finish the creation process.

Wait for several minutes. After a message is displayed indicating successful installation, check the status of the instance. If it is Normal, the deployment is completed.

Installing and Instantiating a Chaincode

Log in to the BCS console.
Find the instance you just created and click Manage Blockchain to go to the Blockchain Management console.
On the login page, enter the username and password, and click Log In.

NOTE:

The username is admin, and the password is the Blockchain Mgmt. Initial Password set when you created the BCS instance. If you have not set this password, use the resource access initial password.

Click

in the upper left corner of the page.

The parameters for chaincode installation are as follows.

Parameter	Setting
Chaincode Name	Enter bcsysq.
Chaincode Version	Enter 1.0
Ledger Storage	File database (goleveldb)
Select All Peers	Check the box.
Organization & Peer	Select peer-0.
Language	Select Golang.
Chaincode File	Add the downloaded chaincode file chaincode_example02.zip.
Chaincode Description	Enter a description of the chaincode.
Code Security Check	This option is displayed only when the chaincode language is Golang. Enable this option to check chaincode security.

Click Install.

After installing the chaincode, click Instantiate in the Operation column of the chaincode list.

The parameters for chaincode instantiation are as follows.

Parameter	Setting
Channel	Select channel.
Chaincode Version	Enter 1.0
Initialization Function	Enter init.
Chaincode Parameters	Enter a,200,b,250.
Endorsement Policy	Select Endorsement from any of the following organizations.
Endorsing Organizations	Select organization.
Privacy Protection Configuration	Select No.

Configuring the Application

On the Instance Management page, click Download Client Configuration on an instance card.
Select Peer Certificates, select organization for Peer Organization, and select User certificate to download.
Download and decompress the demo project code package fabric-restapi-demo.zip to the local PC, and use an IDE to open it.

This demo project is a RESTful client compiled using Golang. It enables chaincode invocation through RESTful APIs to achieve chaincode-based money transfer. Use an IDE such as GoLand to open the package. The following figure shows the content of the project.
Decompress the downloaded user certificate to the usercrypto directory of the project, as shown in the following figure.

Modify parameter settings.

Modify the parameters in the conf.yaml file in the config directory as shown and described in the following figure and tables.

Modify the main.go file in the src/restapi directory, as shown in the following figure and tables.

NOTE:

For each peer that needs to participate in the endorsement, construct an OrgPeer structure including the organization ID and the domain name of the peer. Add the structure to an array of the OrgPeer type, convert the structure into a byte array using the json.Marshal() method, and then convert the structure into a character string. The OrgPeer structure is as follows:

type OrgPeer struct {

OrgId string `json:"orgId"`

PeerDomainName string `json:"peerDomainName"`

}

**Table 4** Parameters
Parameter	Description
Endpoint	IP address and port number of the server bearing the RESTful service endpoint, which can be obtained by performing the following steps: On an instance card, click Container Cluster to go to the CCE console. In the navigation pane, choose Resource Management > Nodes. In the IP column of the target instance, obtain the EIP. The port is fixed to 32621.
Path	Path to the RESTful APIs service. Retain the default value.
CryptoMethod	Encryption algorithm. If the ECDSA algorithm is used, set this parameter to SW.
SignCert	Path to the signature in the downloaded certificate.
PrvKey	Private key in the downloaded certificate.
InvokeReq	Request body parameters. Set these parameters based on the deployed chaincode. The InvokeReq parameter descriptions in the following table are for your reference.
QueryReq	Similar to InvokeReq. Set this parameter based on the deployed chaincode.

**Table 5** InvokeReq parameters
Parameter	Description	Example Value
SignGzipSwitch	Indication of whether GZIP compression is enabled. 0 indicates disabling, and 1 indicates enabling.	"1"
ChannelId	Blockchain channel name.	"channel"
ChaincodeId	Chaincode name.	"testcode"
ChaincodeVersion	Chaincode version.	"1.0"
UserId	User ID issued by the organization CA. The default value for BCS is User1.	"User1"
OrgId	Organization ID in a blockchain. NOTE: On the Channel Management page, click View Peer. The organization ID is the value of MSP ID without "MSP". For example, if the MSP ID is 1232b2032faafee152b58cd82cecf52e49a22a38MSP, the blockchain organization ID is 1232b2032faafee152b58cd82cecf52e49a22a38.	"1232b2032faafee152b58cd82cecf52e49a22a38"
OrgPeers	Organization ID and domain name of each peer.	"[{OrgId:" 1232b2032faafee152b58cd82cecf52e49a22a38", PeerDomainName:"peer-1232b2032faafee152b58cd82cecf52e49a22a38-0 .peer-1232b2032faafee152b58cd82cecf52e49a22a38.default.svc.cluster.local "}]"
Opmethod	Purpose, that is, to invoke or query chaincodes.	"invoke"
Args	Chaincode invoking parameters.	["invoke","a","b","100"]

Build and run main().

The code will read the QueryReq and InvokeReq parameters in conf.yaml and main.go and call /v1/chaincode/operation of the RESTful APIs to invoke the chaincode. The code running result is as follows.

NOTE:

This demo uses a simple REST client to invoke the chaincode through RESTful APIs. The returned invocation result is TransactionID encrypted using Base64, and the query result is data encrypted using Base64. The code is for reference only. You can use this project code to understand how to invoke RESTful APIs.