Node.js网络库:从'data'事件中获取完整数据

Question

我四处寻找,要么找不到我想要回答的确切问题,要么我需要有人向我解释,就像我5岁.

基本上,我有一个使用Net库的Node.js脚本.我正在连接多个主机,发送命令和侦听返回数据.

var net = require('net');

var nodes = [
    'HOST1,192.168.179.8',
    'HOST2,192.168.179.9',
    'HOST3,192.168.179.10',
    'HOST4,192.168.179.11'
];

function connectToServer(tid, ip) {
    var conn = net.createConnection(23, ip);
    conn.on('connect', function() {
        conn.write (login_string);  // login string hidden in pretend variable
    });
    conn.on('data', function(data) {
        var read = data.toString();
        if (read.match(/Login Successful/)) {
            console.log ("Connected to " + ip);
            conn.write(command_string);
        }

        else if (read.match(/Command OK/)) { // command_string returned successful,
                                                    // read until /\r\nEND\r\n/

                    // First part of data comes in here
            console.log("Got a response from  " + ip + ':' + read);
        }
        else {
                 //rest of data comes in here
             console.log("Atonomous message from " + ip + ':' + read);
        }
    });
    conn.on('end', function() {
        console.log("Lost conncection to " + ip + "!!");
    });
    conn.on('error', function(err) {
        console.log("Connection error: " + err + " for ip " + ip);
    });
}

nodes.forEach(function(node) {
    var nodeinfo = node.split(",");
    connectToServer(nodeinfo[0], nodeinfo[1]);
});

数据最终被分成两个块.即使我将数据存储在哈希中,并在读取/\r \nEND\r \n/delimiter时将第一部分附加到余数,但是中间缺少一个块.如何正确缓冲数据以确保从流中获取完整的消息？

编辑:好的,这似乎更好:

function connectToServer(tid, ip) {
        var conn = net.createConnection(23, ip);

        var completeData = '';

        conn.on('connect', function() {
                conn.write (login_string);
        });
        conn.on('data', function(data) {
                var read = data.toString();

                if (read.match(/Login Successful/)) {
                        console.log ("Connected to " + ip);

                        conn.write(command_string);
                }
                else {
                        completeData += read;
                }

                if (completeData.match(/Command OK/)) {
                        if (completeData.match(/\r\nEND\r\n/)) {
                                console.log("Response: " + completeData);
                        }
                }
        });
        conn.on('end', function() {
                console.log("Connection closed to " + ip );
        });
        conn.on('error', function(err) {
                console.log("Connection error: " + err + " for ip " + ip);
        });
}

我最大的问题显然是逻辑错误.我要么等待开始回复的块,要么等待结束它的块.我没有把一切都保存在中间.

我想如果我想得到所有关于它的节点,我应该在每个完整的消息进入时触发一个事件(以空白行开头,在一行上以'END'结尾),并在那里进行处理.

Answer 1

在收到结束事件之前，您不应对接收到的数据做任何事情。结束回调意味着所有数据块都已通过流发送到您的回调。如果数据包含多个块，则需要在函数闭包内创建一个变量以存储该数据。忽略这一事实，大多数程序都可以正常工作，因为数据通常是成块出现的。但有时并非如此。它甚至不一定取决于数据量。如果您遇到这种情况，我创建了一个示例来演示如何处理它。我基本上使用了您的代码，但是删除了所有的绒毛...这只是演示了收集所有数据并进行处理所需的逻辑。

function connectToServer(tid, ip) {
    var conn = net.createConnection(23, ip);
    var completeData = '';

    conn.on('connect', function() {
        conn.write (login_string);  // login string hidden in pretend variable
    });
    conn.on('data', function(data) {
        completeData += data;
        var dataArray = completeData.split('your delimiter');
        if(dataArray.size > 1) { //If our data was split into several pieces, we have a complete chunk saved in the 0th position in the array
            doWorkOnTheFirstHalfOfData(dataArray[0]);
            completeData = dataArray[1];// The second portion of data may yet be incomplete, thise may need to be more complete logic if you can get more than one delimeter at a time...
        }
    });
    conn.on('end', function() {
        //do stuff with the "completeData" variable in here.
    });
}

Answer 2

我的问题是一个逻辑问题。我要么寻找开始消息的块，要么寻找结束消息的块，并忽略中间的所有内容。我猜想整个回复都会分成一两块。

这是从上面粘贴的工作代码。可能有一种更节点化的方法来做到这一点（我真的应该为每个信息块发出一个事件），但我会将其标记为答案，除非有人在明天这个时候发布更好的版本。

function connectToServer(tid, ip) {
        var conn = net.createConnection(23, ip);

        var completeData = '';

        conn.on('connect', function() {
                conn.write (login_string);
        });
        conn.on('data', function(data) {
                var read = data.toString();

                if (read.match(/Login Successful/)) {
                        console.log ("Connected to " + ip);

                        conn.write(command_string);
                }
                else {
                        completeData += read;
                }

                if (completeData.match(/Command OK/)) {
                        if (completeData.match(/\r\nEND\r\n/)) {
                                console.log("Response: " + completeData);
                        }
                }
        });
        conn.on('end', function() {
                console.log("Connection closed to " + ip );
        });
        conn.on('error', function(err) {
                console.log("Connection error: " + err + " for ip " + ip);
        });
}