Question

您好，我正在尝试学习Corda的一些概念。我的系统上本地运行了一个Cordapp。我想与它集成前端。我该怎么办？

Answer 1

在Corda中，您通过RPC与节点进行交互。您的前端服务器需要：

创建到该节点的RPC连接
使用此RPC连接发出命令并从节点读取数据

这是在example中创建与Spring中的节点的RPC连接：

private const val CORDA_USER_NAME = "config.rpc.username"
private const val CORDA_USER_PASSWORD = "config.rpc.password"
private const val CORDA_NODE_HOST = "config.rpc.host"
private const val CORDA_RPC_PORT = "config.rpc.port"

/**
 * Wraps a node RPC proxy.
 *
 * The RPC proxy is configured based on the properties in `application.properties`.
 *
 * @param host The host of the node we are connecting to.
 * @param rpcPort The RPC port of the node we are connecting to.
 * @param username The username for logging into the RPC client.
 * @param password The password for logging into the RPC client.
 * @property proxy The RPC proxy.
 */
@Component
open class NodeRPCConnection(
        @Value("\${$CORDA_NODE_HOST}") private val host: String,
        @Value("\${$CORDA_USER_NAME}") private val username: String,
        @Value("\${$CORDA_USER_PASSWORD}") private val password: String,
        @Value("\${$CORDA_RPC_PORT}") private val rpcPort: Int): AutoCloseable {

    lateinit var rpcConnection: CordaRPCConnection
        private set
    lateinit var proxy: CordaRPCOps
        private set

    @PostConstruct
    fun initialiseNodeRPCConnection() {
            val rpcAddress = NetworkHostAndPort(host, rpcPort)
            val rpcClient = CordaRPCClient(rpcAddress)
            val rpcConnection = rpcClient.start(username, password)
            proxy = rpcConnection.proxy
    }

    @PreDestroy
    override fun close() {
        rpcConnection.notifyServerAndClose()
    }
}

这是在Spring控制器中使用RPC连接的example：

/**
 * A CorDapp-agnostic controller that exposes standard endpoints.
 */
@RestController
@RequestMapping("/") // The paths for GET and POST requests are relative to this base path.
class StandardController(
        private val rpc: NodeRPCConnection) {

    companion object {
        private val logger = LoggerFactory.getLogger(RestController::class.java)
    }

    private val proxy = rpc.proxy

    @GetMapping(value = "/status", produces = arrayOf("text/plain"))
    private fun status() = "200"

    @GetMapping(value = "/servertime", produces = arrayOf("text/plain"))
    private fun serverTime() = LocalDateTime.ofInstant(proxy.currentNodeTime(), ZoneId.of("UTC")).toString()

    @GetMapping(value = "/addresses", produces = arrayOf("text/plain"))
    private fun addresses() = proxy.nodeInfo().addresses.toString()

    @GetMapping(value = "/identities", produces = arrayOf("text/plain"))
    private fun identities() = proxy.nodeInfo().legalIdentities.toString()

    @GetMapping(value = "/platformversion", produces = arrayOf("text/plain"))
    private fun platformVersion() = proxy.nodeInfo().platformVersion.toString()

    @GetMapping(value = "/peers", produces = arrayOf("text/plain"))
    private fun peers() = proxy.networkMapSnapshot().flatMap { it.legalIdentities }.toString()

    @GetMapping(value = "/notaries", produces = arrayOf("text/plain"))
    private fun notaries() = proxy.notaryIdentities().toString()

    @GetMapping(value = "/flows", produces = arrayOf("text/plain"))
    private fun flows() = proxy.registeredFlows().toString()

    @GetMapping(value = "/states", produces = arrayOf("text/plain"))
    private fun states() = proxy.vaultQueryBy<ContractState>().states.toString()
}

您会注意到，您需要使用Java类来创建与节点的连接。这意味着将需要使用JVM语言编写Web服务器。另外，您可以使用Graal之类的东西以非JVM语言编写服务器，并将其编译为JVM字节码。有一个示例here。

如何将前端与我的自定义Cordapp集成？

1 个答案: