You can use networking in Web in the following two ways:
Optionally, you can use WebSockets or WebRTC from JavaScript to implement your own networking. You can’t use any .NET networking classes within the Web platform because JavaScript code doesn’t have direct access to internet protocol (IP) sockets to implement network connectivity. Specifically, Web doesn’t support any .NET classes within the System.Net namespace.
Unity supports the UnityWebRequest class in WebGL. To implement the UnityWebRequest class, Unity uses the JavaScript Fetch API, which uses the browser to handle web requests. This imposes security restrictions on accessing cross-domain resources.
If you send a web request to a server other than the one that hosts the Unity content, the server you’re sending it to must authorize the Unity content.
WebGL でクロスドメインのウェブリソースにアクセスするには、アクセスしようとしているサーバーが オリジン間リソース共有 (CORS) を使用してドメインのウェブリソースを認証する必要があります。
If you try to access content using UnityWebRequest, and the remote server doesn’t have CORS set up or configured correctly, an error like the following appears in the browser console:
Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at http://myserver.com/. この問題はリソースを同じドメインに移すか、 CORS を使用可能にすると修正されます
サーバーは、送信する http レスポンスに Access-Control ヘッダーを加えて、どのウェブページがウェブブラウザーからその情報を読み取る権限を持っているかを示す必要があります。
For a demonstration of how to add Access-Control headers that allow Unity Web to access resources on a web server from any origin, refer to the following example. This example includes common request headers and allows the GET, POST or OPTIONS methods:
"Access-Control-Allow-Credentials": "true",
"Access-Control-Allow-Headers": "Accept, X-Access-Token, X-Application-Name, X-Request-Sent-Time",
"Access-Control-Allow-Methods": "GET, POST, OPTIONS",
"Access-Control-Allow-Origin": "*",
Don’t use code that blocks a UnityWebRequest download, such as this:
while(!www.isDone) {}
You can’t block the thread to wait for a UnityWebRequest download to finish otherwise your application freezes. Because WebGL is single threaded, and the fetch API in JavaScript is asynchronous, your download might not finish unless you return control to the browser. Instead, use a Coroutine and a yield statement to wait for the download to finish. For more information, see Examples of coroutines using UnityWebRequest.
Unity Multiplayer enables communication via the WebSockets protocol. Refer to NetworkServer.useWebSockets.
WebGL doesn’t allow direct access to IP sockets, but you can use WebSockets or WebRTC (the two most common networking protocols supported by browsers) to get around this. While WebSockets are widely supported, WebRTC allows peer-to-peer connections between browsers and unreliable connections. Unity doesn’t have a built-in API that allows you to use WebSockets or WebRTC, but you can use a JavaScript plug-in to implement this. You can find plug-ins that implement WebSocket networking on the Unity Asset Store.