在 Node.js 中发出 HTTP 请求并接收 multipart/x-mixed-replace 响应 [英] Making HTTP request and receiving multipart/x-mixed-replace response in Node.js
问题描述
我需要向外部服务器发出 HTTP GET 请求以开始接收事件.请求后,我立即得到 multipart/x-mixed-replace
响应.当一个事件发生时,它作为 XML 消息连同指示这部分结束的边界一起发送.
I need to make a HTTP GET request to foreign server to start receiving events. After request I immediately get multipart/x-mixed-replace
response. When an event occurs, it's sent as XML message together with boundary indicating the end of this part.
现在我必须在 Node.js 中实现它.对于正常请求,我使用 node-rest-client
,调用它的 get()
方法并将我的逻辑放在方法的回调中.问题是回调仅在响应完成时执行,并且使用 multipart/x-mixed-replace
直到连接关闭.
Now I must implement it in Node.js. With normal request I use node-rest-client
, call its get()
method and put my logic in method's callback. Trouble is that callback is executed only when response is finished and with multipart/x-mixed-replace
it isn't until connection closes.
是否有其他一些 NPM 模块可以解决这个问题?我搜索了 NPM 注册表,但我发现的结果似乎不适合该任务.还是在纯 Node 中做更好?我是这样,请举个例子.
Is there some other NPM module that does the trick? I searched NPM registry but results I found seem unappropriate to the task. Or is it better to do it in pure Node? I so, please provide an example.
推荐答案
这是我自己的实现:
const webStream = {
get: function (url, callback) {
let webClient;
if (url.startsWith("http://")) {
webClient = require("http");
} else if (url.startsWith("https://")) {
webClient = require("https");
} else {
throw "Unsupported protocol.";
}
let clientRequest = webClient.get(url, function (response) {
let context = {
url: url,
boundary: "",
contentType: "",
contentLength: 0
};
let headersCompleted = false;
let bodyCompleted = false;
let buffer = null;
let receivedBodyChunk = 0;
response.on("data", function (chunk) {
if (!headersCompleted) {
let headers = chunk.toString().split(/\r?\n/);
context.boundary = headers[0].substring(2);
context.contentType = headers[1].split(":")[1].trim();
context.contentLength = parseInt(headers[2].split(":")[1]);
buffer = Buffer.alloc(context.contentLength);
headersCompleted = true;
} else {
if (!bodyCompleted) {
if (receivedBodyChunk < context.contentLength) {
chunk.copy(buffer, receivedBodyChunk, 0, chunk.byteLength);
receivedBodyChunk += chunk.byteLength;
if (receivedBodyChunk === context.contentLength) {
bodyCompleted = true;
}
}
}
if (bodyCompleted) {
callback(buffer, context);
headersCompleted = false;
bodyCompleted = false;
buffer = null;
receivedBodyChunk = 0;
}
}
});
});
return {
url: url,
handler: clientRequest,
on: function (type, listener) {
clientRequest.on(type, listener);
},
abort: function () {
clientRequest.abort();
}
};
}
};
let stream = webStream.get("http://127.0.0.1:8090/", function (data, context) {
// data: Received content (Buffer)
// context: { url, boundary, contentType, contentLength }
// TODO: Do something here...
});
// stream.abort();
// stream.on("error", function(e) {
// console.log("Error: " + e.message);
// });
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