如何使 Flask/保持 Ajax HTTP 连接处于活动状态?

问题描述：

我有一个 jQuery Ajax 调用，如下所示:

I have a jQuery Ajax call, like so:

    $("#tags").keyup(function(event) {
      $.ajax({url: "/terms",
        type: "POST",
        contentType: "application/json",
        data: JSON.stringify({"prefix": $("#tags").val() }),
        dataType: "json",
        success: function(response) { display_terms(response.terms); },
      });

我有一个像这样的 Flask 方法:

I have a Flask method like so:

@app.route("/terms", methods=["POST"])
def terms_by_prefix():
    req = flask.request.json
    tlist = terms.find_by_prefix(req["prefix"])
    return flask.jsonify({'terms': tlist})

tcpdump 显示 HTTP 对话框:

tcpdump shows the HTTP dialog:

POST /terms HTTP/1.1
Host: 127.0.0.1:5000
User-Agent: Mozilla/5.0 (X11; Linux i686; rv:12.0) Gecko/20100101 Firefox/12.0
Accept: application/json, text/javascript, */*; q=0.01
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
Content-Type: application/json; charset=UTF-8
X-Requested-With: XMLHttpRequest
Referer: http://127.0.0.1:5000/
Content-Length: 27
Pragma: no-cache
Cache-Control: no-cache

{"prefix":"foo"}

然而，Flask 回复时没有保持活动状态.

However, Flask replies without keep-alive.

HTTP/1.0 200 OK
Content-Type: application/json
Content-Length: 445
Server: Werkzeug/0.8.3 Python/2.7.2+
Date: Wed, 09 May 2012 17:55:04 GMT

{"terms": [...]}

真的没有实现keep-alive吗?

Is it really the case that keep-alive is not implemented?

答

Werkzeug 的集成 Web 服务器基于 Python 标准库中的 BaseHTTPServer 构建.如果您将其 HTTP 协议版本设置为 1.1，BaseHTTPServer 似乎支持 Keep-Alives.

Werkzeug's integrated web server builds on BaseHTTPServer from Python's standard library. BaseHTTPServer seems to support Keep-Alives if you set its HTTP protocol version to 1.1.

Werkzeug 不会这样做，但如果您准备入侵 Flask 用来实例化 Werkzeug 的 BaseWSGIServer 的机器，您可以自己动手.参见调用 werkzeug.serving.run_simple() 的 Flask.run().你要做的归结为BaseWSGIServer.protocol_version = "HTTP/1.1".

Werkzeug doesn't do it but if you're ready to hack into the machinery that Flask uses to instantiate Werkzeug's BaseWSGIServer, you can do it yourself. See Flask.run() which calls werkzeug.serving.run_simple(). What you have to do boils down to BaseWSGIServer.protocol_version = "HTTP/1.1".

我还没有测试过解决方案.我想您确实知道 Flask 的 Web 服务器应该仅用于开发.

I haven't tested the solution. I suppose you do know that Flask's web server ought to be used for development only.

如何使 Flask/保持 Ajax HTTP 连接处于活动状态?

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