CODEWITHSUNDEEP
javascriptc#.netblazorblazor-webassembly
bashis
bashis

Reputation: 1243

Use Blazor with non-http(s) protocol

I'm working on an application that is supposed to run over a custom transfer protocol which is pretty much the same as http but has a package:// prefix instead of http:// in the beginning of the query string. So a query to a resource named index.html would look like package://resources/index.html.

I would like to deploy a Blazor WebAssembly application into this environment. The problem is that as soon as Blazor's index.html gets loaded - it loads blazor.webassembly.js which uses fetch() to load blazor.boot.json. However, fetch() seems to only be working with http and https (not sure why) and I get this error:

    blazor.webassembly.js:1 Fetch API cannot load package://package_name/wwwroot/_framework/blazor.boot.json. 
URL scheme "package" is not supported.
(anonymous) @ blazor.webassembly.js:1
blazor.webassembly.js:1 TypeError: Failed to fetch
    at Function.<anonymous> (blazor.webassembly.js:1)
    at blazor.webassembly.js:1
    at Object.next (blazor.webassembly.js:1)
    at blazor.webassembly.js:1
    at new Promise (<anonymous>)
    at blazor.webassembly.js:1
    at Function.initAsync (blazor.webassembly.js:1)
    at blazor.webassembly.js:1
    at blazor.webassembly.js:1
    at Object.next (blazor.webassembly.js:1)

I was thinking that maybe it would help to override fetch with a function that would use XMLHttpRequest inside but I'm not sure if that's doable in js. Overall, I'm wondering how to make Blazor work in an application that is run over a protocol that is not http or https but is very similar except for the scheme naming.

Upvotes: 0

Views: 771

Answers (1)

Just the benno
Just the benno

Reputation: 2601

The short answer is it is not possible. After all, each browser is an HTTP client. While some browsers have adopted other protocols for special purposes like RTC for web conferencing, they can't support custom protocols out of the box. There might be a way to write a browser extension, that enables the usage of package://. Or you find a way to "trick" the browser into making an HTTP(s) call of URIs starting with "package://" via manipulating browser preference or OS values. But again it would require you to do it for each machine that should execute your application.

The second possible problem lies within the WASM application. If the WASM application wants to interact with another service, like an API, you would normally use a HttpClient instance. Blazor WASM provides a handler that uses the browser fetch APIto make these calls. Because a WASM application runs in a special sandbox mode, you can't access all the system-level features like you would in a normal .NET application including (but not limited) to sockets. So, you can't implement a customer transport protocol here either.

If you still want to have a Blazor application and using your custom protocols for the "internal" communication, Blazor Server Side could be an option. There you can implement your own transport protocol (with Sockets and all .NET classes/libraries) while using standard technology to interact with the browser.

Upvotes: 2

Related Questions