使用 wsDualHttpBinding 通过 Internet 连接到 WCF 服务超时

问题描述

仍在 WCF 学习曲线上:

Still on the WCF learning curve:

我已经设置了一个自托管的 WCF 服务 (WSDualHttpBinding)，它在我自己的计算机上运行良好，它位于防火墙后面.如果我在自己的计算机上运行客户端，则一切正常.

I've set up a self-hosted WCF Service (WSDualHttpBinding), which works fine on my own computer, which resides behind a firewall. If I run the client on my own computer, everything works great.

现在我在网络外的计算机上安装了客户端，并且我尝试通过动态 DNS 访问该服务，如下所示:http://mydomain.dyndns.org:8000/MyService.我的端口转发问题在上一个问题中得到解决；我现在可以在浏览器中看到该服务已启动.

Now I installed the client on a computer outside my network, and I'm trying to access the service via a dynamic DNS, like so: http://mydomain.dyndns.org:8000/MyService. My port forwarding issues were taken care of in a previous question; I can now see the service is up in my browser.

但是现在当我尝试在另一台机器上运行客户端时，我收到以下错误消息:在 00:01:00 分配的超时时间内未完成打开操作.分配给此操作的时间可能有是更长暂停时间的一部分."

But now when I try to run the client on the other machine, I get the following error message: "The open operation did not complete within the allotted timeout of 00:01:00. The time allotted to this operation may have been a portion of a longer timeout."

我已经禁用了服务的安全性，所以不是这样.还有什么可能阻止连接发生?

I have disabled security on the service, so that's not it. What else might be preventing the connection from happening?

推荐答案

WSDualHttpBinding 和大多数人连接到互联网的方式存在一个真正的问题 - 在路由器后面意味着，至少正如您已经发现的那样，IPv4，让 NAT 毁了派对.

There's a real problem with WSDualHttpBinding and the way most people are connected to the internet - being behind a router means, at least with IPv4, having NAT ruin the party, as you've already discovered.

使用 WSDualHttpBinding，您有两个连接:从客户端到服务器，以及从服务器到客户端.

With WSDualHttpBinding, you have two connections: From the client to the server, and from the server to the client.

通常，客户端到服务器的连接没什么大不了的 - 大多数通信都是通过互联网完成的.在您的情况下，您似乎在防火墙后面，并且您已经打开/转发了所需的端口.但这并没有解决第二个连接的问题——从服务器到客户端.基本上，第二个连接发生的情况是客户端充当服务器，而服务器充当客户端.因此，您需要对连接到您的服务的每个客户端进行相同的端口打开/转发，因为它也充当服务器！这当然是对您服务的每个用户的不合理要求.这就是 WSDualHttpBinding 更适合服务器到服务器通信的原因，其中设置是一次性的.

Usually, the client-to-server connection isn't a big deal - that's how most communication is done over the internet. In your case, it seems that you were behind a firewall and you've opened/forwarded the needed ports. But that doesn't solve the problem of the second connection - from the server to the client. Basically what happens with that second connection is that the client acts as a server, and the server acts as a client. So you need to do the same port opening/forwarding with each and every client that connects to your service, because it also acts as a server! This is of course an unreasonable demand to make of every user of your service. That's why WSDualHttpBinding is more suited to server-to-server communications, where the setup is a one-time affair.

与其尝试让 WSDualHttpBinding 工作，我建议您切换到 NetTcpBinding.由于 WSDualHttpBinding 和 NetTcpBinding 都是 WCF-only、Microsoft-only、专有的连接方案，所以在互操作性方面不会损失太多.另一方面，您获得的却很多:

Instead of trying to get WSDualHttpBinding to work, I suggest you switch to NetTcpBinding. Since both WSDualHttpBinding and NetTcpBinding are WCF-only, Microsoft-only, proprietary connection schemes, you're not losing much in the way of interoperability. What you're gaining, on the other hand, is a lot:

1. NetTcpBinding 只使用一个连接，从客户端到服务器，同时允许像 WSDualHttpBinding 这样的双向通信.因此无需在客户端处理端口打开/转发 - NAT 不是问题.
2. 通信协议是二进制的，比 WSDualHttpBinding 中使用的纯文本 XML 更紧凑.更少的数据传输意味着更好的服务.
3. 使用 NetTcpBinding，您可以在客户端断开连接时获得即时通知，因为套接字已关闭.无需像使用 WSDualHttpBinding 那样等待 HTTP 超时.
4. 单个连接意味着没有任何东西可以不同步 - 使用 WSDualHttpBinding，两个连接之一可能会断开，而另一个可能仍然处于活动状态，只有一种方式通信.WCF 有办法解决这个问题，但最好首先避免这个问题.

1. NetTcpBinding uses only a single connection, from the client to the server, while allowing two way communication like WSDualHttpBinding. So there's no need to deal with port opening/forwarding on the client side - NAT is a non-issue.
2. The communication protocol is binary and is more compact than the plain-text XML used in WSDualHttpBinding. Less data transfer means a better performing service.
3. With NetTcpBinding, you can get instant notification of when a client disconnects, since a socket is closed. No need to wait for a HTTP timeout like you do with WSDualHttpBinding.
4. A single connection means there nothing that can go out of sync - with WSDualHttpBinding, one of the two connections may drop while the other may still be active, having only one way communication. WCF has a way of dealing with that, but it's better to just avoid the issue in the first place.

切换到 NetTcpBinding 通常只需要更改配置 - 代码保持不变.这很简单，速度很快，麻烦也少得多，最重要的是 - 它很管用.

Switching to NetTcpBinding usually only requires a configuration change - the code remains the same. It's simple, it's fast, it's much less of a hassle and most importantly - it just works.

这篇关于使用 wsDualHttpBinding 通过 Internet 连接到 WCF 服务超时的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！