在量化交易和自动化策略开发中，有时会用到http服务。发明者量化平台近日新增了 _Serve() 函数，为用户提供了灵活的 HTTP、HTTPS 和 TCP 服务创建能力。通过该功能，开发者可以简化服务配置过程，并在量化环境中实现更多自定义服务，使策略设计更加流畅便捷。本文将介绍 _Serve() 函数的使用场景和基本操作，帮助您快速上手发明者量化的这一全新功能。

关于_Serve()已更新在平台API文档：

https://www.fmz.com/syntax-guide/fun/global/__serve

需求

平台升级了_Serve()函数（由于之前JavaScript语言没有创建服务的功能，该函数只支持JavaScript语言的策略），简单说就是让策略拥有了可以创建网络服务的能力。基于此功能我们能开发出很多功能，解决很多需求。例如让策略拥有对外的接口、数据转发、配合平台的通用协议功能无缝封装FMZ平台不支持的交易所等。

本篇我们就以：「配合平台的通用协议功能无缝封装FMZ平台不支持的交易所」这个需求来举例实现。在往期文章「通用协议指南」中我们使用Python语言对OKX交易所以现货模式封装了API（由于FMZ本身支持OKX，这里使用OKX只是举例，对于其它FMZ平台没有接入的交易所都适用）。文中Python的通用协议程序需要单独运行起来，当JavaScript语言支持了_Serve()函数之后，JavaScript语言的策略接入通用协议就更加简单了。

我们将待封装的交易所接口的通用协议封装为「模板类库」直接集成在策略中，这样策略就无缝接入了在FMZ上未支持的交易所。对于如何配置「通用协议」交易所对象这里就不再赘述，可以查阅文章：

https://www.fmz.com/digest-topic/10518

• 在平台上通用协议交易所配置如图：

  

  可以在模板设计时，通过/OKX识别配置的通用协议交易所对象属于哪一个交易所。

通用协议模板实现

首先在发明者量化交易平台创建一个新策略，策略类型设置为模板类库，策略语言为JavaScript语言。

模板参数设计

给创建好的策略模板增加3个参数：

然后就可以开始设计、编写通用协议模板的代码了。

代码实现

代码使用TS风格编写，$.startService()函数为模板的接口函数，用来启动通用协议服务。

            ts
            
            
// @ts-check

$.startService = function (address, port, proxyConfig) {
    __Serve(`http://${address}:${port}`, function (ctx, proxyConfig) {
        // interface
        interface IData {
            data: object
            raw: object
        }
        
        interface IError {
            error: any
        }
        
        // custom protocol for OKX
        class CustomProtocolOKX {
            apiBase: string = "https://www.okx.com"
            accessKey: string
            secretKey: string
            passphrase: string
            proxyConfig: string = ""
            simulate: boolean = false
            
            constructor(accessKey: string, secretKey: string, passphrase: string, simulate?: boolean, proxyConfig?: string) {
                this.accessKey = accessKey
                this.secretKey = secretKey
                this.passphrase = passphrase
                if (typeof(simulate) == "boolean") {
                    this.simulate = simulate
                }
                this.proxyConfig = proxyConfig
            }
            
            httpReq(method: string, path: string, query: string = "", params: {[key: string]: any} = {}, headers: {key: string, value: string | ArrayBuffer}[] = []): {[key: string]: any} {
                let ret = null
                let options = {
                    method: method,                    
                    headers: {
                        'User-Agent': 'Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.6) Gecko/20091201 Firefox/3.5.6', 
                        'Content-Type': 'application/json; charset=UTF-8',
                        'x-simulated-trading': this.simulate ? "1" : "0"
                    },
                }
                
                // headers
                if (Array.isArray(headers) && headers.length > 0) {
                    for (var pair of headers) {
                        options.headers[pair.key] = pair.value
                    }
                }
                
                let url = ""
                if (method == "GET") {
                    if (typeof(query) == "string" && query.length > 0) {
                        url = `${this.apiBase}${path}?${query}`
                    } else {
                        url = `${this.apiBase}${path}`
                    }
                } else {
                    url = `${this.apiBase}${path}`
                    options.body = JSON.stringify(params)
                }

                // request
                try {
                    if (this.proxyConfig != "") {
                        url = `${this.proxyConfig}${url}`
                    }
                    ret = JSON.parse(HttpQuery(url, options))
                } catch(e) {
                    return null
                }
    
                return ret
            }

            callSignedAPI(method: string, path: string, query: string = "", params: {[key: string]: any} = {}): {[key: string]: any} {
                const strTime = new Date().toISOString().slice(0, -5) + 'Z'
                let jsonStr = ""
                if (method == "GET") {
                    jsonStr = Object.keys(params).length > 0 ? JSON.stringify(params) : ""
                } else {
                    jsonStr = Object.keys(params).length > 0 ? JSON.stringify(params) : "{}"
                }                
                let message = `${strTime}${method}${path}${jsonStr}`
                if (method === "GET" && query !== "") {
                    message = `${strTime}${method}${path}?${query}${jsonStr}`
                }

                const signature = Encode("sha256", "string", "base64", message, "string", this.secretKey)
                let headers = []
                headers.push({key: "OK-ACCESS-KEY", value: this.accessKey})
                headers.push({key: "OK-ACCESS-PASSPHRASE", value: this.passphrase})
                headers.push({key: "OK-ACCESS-TIMESTAMP", value: strTime})
                headers.push({key: "OK-ACCESS-SIGN", value: signature})                

                return this.httpReq(method, path, query, params, headers)
            }
            
            urlEncode(params: {[key: string]: string | number}): string {
                let encodeParams: string[] = []
                for (const [key, value] of Object.entries(params)) {
                    encodeParams.push(`${encodeURIComponent(key)}=${encodeURIComponent(value)}`)
                }

                return encodeParams.join("&")
            }

            symbol2Inst(symbol: string): string {
                let arr = symbol.split("_")
                if (arr.length >= 2) {
                    return `${arr[0]}-${arr[1]}`.toUpperCase()
                } else {
                    return `${arr[0]}-USDT`.toUpperCase()
                }
            }

            getSymbol(inst: string): string {
                let arr = inst.split("-")
                if (arr.length >= 2) {
                    return `${arr[0]}_${arr[1]}`.toUpperCase()
                } else {
                    return `${arr[0]}-USDT`.toUpperCase()
                }
            }
            
            // The following code encapsulates OKX's interface
            GetTicker(symbol: string): IData | IError {
                // GET /api/v5/market/ticker , param: instId 

                let inst = this.symbol2Inst(symbol)
                let ret = this.httpReq("GET", "/api/v5/market/ticker", `instId=${inst}`)

                let retData = {}
                for (var ele of ret["data"]) {
                    retData["symbol"] = this.getSymbol(ele["instId"])
                    retData["buy"] = ele["bidPx"]
                    retData["sell"] = ele["askPx"]
                    retData["high"] = ele["high24h"]
                    retData["low"] = ele["low24h"]
                    retData["open"] = ele["open24h"]
                    retData["last"] = ele["last"]
                    retData["vol"] = ele["vol24h"]
                    retData["time"] = ele["ts"]
                }

                return {data: retData, raw: ret}
            }
            
            GetAccount(): IData | IError {
                // GET /api/v5/account/balance
                
                let ret = this.callSignedAPI("GET", "/api/v5/account/balance")

                let retData = []
                for (var ele of ret["data"]) {
                    for (var detail of ele["details"]) {
                        let asset = {"currency": detail["ccy"], "free": detail["availEq"], "frozen": detail["ordFrozen"]}
                        if (detail["availEq"] == "") {
                            asset["free"] = detail["availBal"]
                        }
                        retData.push(asset)
                    }
                }
                
                return {data: retData, raw: ret}
            }

            IO(method: string, path: string, params: {[key: string]: any}): {[key: string]: any} {
                let ret = null 
                if (method == "GET") {
                    ret = this.callSignedAPI(method, path, this.urlEncode(params))
                } else {
                    ret = this.callSignedAPI(method, path, "", params)
                }

                return {data: ret}
            }
        }
        
        // protocol factory
        class ProtocolFactory {
            static createExWrapper(accessKey: string, secretKey: string, exName: string): any {
                let protocol = null
                if (exName == "/OKX") {
                    try {
                        let passphrase = ""
                        let simulate = false
                        let arrSecretKey = secretKey.split(",")

                        if (arrSecretKey.length == 2) {
                            secretKey = arrSecretKey[0]
                            passphrase = arrSecretKey[1]
                        } else if (arrSecretKey.length == 3) {
                            secretKey = arrSecretKey[0]
                            passphrase = arrSecretKey[1]
                            simulate = arrSecretKey[2] == "simulate" ? true : false 
                        } else {
                            return null
                        }
                        protocol = new CustomProtocolOKX(accessKey, secretKey, passphrase, simulate, proxyConfig)
                    } catch(e) {
                        Log("e.name:", e.name, "e.stack:", e.stack, "e.message:", e.message)
                        return null
                    }
                }
                return protocol
            }
        }
        
        // http service
        let resp = {}
        let reqMethod = ctx.method()
        let reqPath = ctx.path()
        let httpMethod = ctx.header("Http-Method")
        let reqBody = null

        try {
            reqBody = JSON.parse(ctx.body())
        } catch(e) {
            resp = {error: {name: e.name, stack: e.stack, message: e.message, errDesc: "JSON parse error."}}
        }

        // onPost
        if (reqMethod == "POST") {
            if (!["access_key", "secret_key", "method", "params"].every(key=> key in reqBody)) {
                resp = {error: {reqBody: reqBody, errDesc: "reqBody error."}}
            }

            if ("error" in resp) {
                ctx.write(JSON.stringify(resp))
                return 
            }

            let accessKey = reqBody["access_key"]
            let secretKey = reqBody["secret_key"]
            let method = reqBody["method"]
            let params = reqBody["params"]

            let protocol = ProtocolFactory.createExWrapper(accessKey, secretKey, reqPath)
            if (!protocol) {
                ctx.write(JSON.stringify({error: {errDesc: "createExWrapper error."}}))
                return 
            }

            // process GetTicker / GetAccount ...
            if (method == "ticker") {
                if (!["symbol"].every(key=> key in params)) {
                    resp = {error: {params: params, errDesc: "params error."}}
                } else {
                    let symbol = params["symbol"]
                    resp = protocol.GetTicker(symbol)
                }
            } else if (method == "accounts") {
                resp = protocol.GetAccount()
            } else if (method.slice(0, 6) == "__api_") {
                resp = protocol.IO(httpMethod, method.slice(6), params)
            } else {
                ctx.write(JSON.stringify({error: {method: method, errDesc: "method not support."}}))
                return 
            }

            ctx.write(JSON.stringify(resp))
        }
    }, proxyConfig)
}

function init() {
    $.startService(address, port, proxyConfig)
    Log("启动通用协议服务，address:", address, "，port:", port, "#FF0000")
    if (proxyConfig != "") {
        Log("设置代理：", proxyConfig, "#FF0000")
    }
}

篇幅有限，这里就不把所有接口都实现了，仅实现了行情查询、资产查询、IO调用，有兴趣的同学可以实现所有接口；设计完成，保存模板代码，模板名称保存为："TypeScript版本通用协议范例"。

测试策略

将OKX交易所的apikey、secretkey、passphrase等配置完成后，我们可以编写一个测试策略来测试。

策略勾选我们设计好的模板类库：

测试策略代码：

            javascript
            
            
function main() {
    // 测试GetTicker
    Log(`exchange.GetTicker():`, exchange.GetTicker())

    // 测试GetAccount
    Log(`exchange.GetAccount():`, exchange.GetAccount())

    // 测试exchange.IO
    Log(`exchange.IO("api", "POST", "/api/v5/trade/cancel-all-after", "timeOut=0"):`, exchange.IO("api", "POST", "/api/v5/trade/cancel-all-after", "timeOut=0"))

    // 输出通用协议添加的交易所名称
    Log(`exchange.GetName():`, exchange.GetName())

    // 输出通用协议添加的交易所标签
    Log(`exchange.GetLabel():`, exchange.GetLabel())
}

运行测试

可以看到，策略只是勾选了一个模板，就实现了OKX交易所（虽然OKX交易所已经支持，例如这里OKX替换为一个FMZ还未接入的交易所）的无缝接入。