C#•3y ago

❔ REST API but it is HttpListener only available

Hello there, I got a challenge to write good scalable C# REST API app by using only .NET 7 (instead of ASP .NET) with HttpListener.
So I have some questions:
1) As I understood, it will only one

HttpListener

HttpListener

instance that catch all requests on different endpoints - not dedicated

HttpListener

HttpListener

to dedicated endpoint?
2) After I catch connection, I should do

httpListenerInstance.GetContextAsync()

httpListenerInstance.GetContextAsync()

and then transfer it to

ThreadPool.QueueUserWorkItem

ThreadPool.QueueUserWorkItem

?
3) How to execute some logic on needed endpoint? I found an answer by notifying all endpoints like hey my dudes, it is new connection to
/endpoint
/endpoint
can all of you handle it and execute if needed by checking itself context by using Observer pattern. But I see it may slower my system, is it any way to notify only 1 needed endpoint class?
4)

ThreadPool.QueueUserWorkItem

ThreadPool.QueueUserWorkItem

or it is better to create custom class which will store

ConcurrentQueue<HttpListenerContext>

ConcurrentQueue<HttpListenerContext>

with all my connections and then run another Task which will peak and notify endpoint func (see p.2 and p.3)?

Please leave good advices - I can not use sweety ASP .NET.

JakenVeina•10/14/23, 3:14 AM

1) Yes, that seems correct, assuming there's lots of overlap between the endpoints you're listening to. If not, it may be better to split them up, to reduce the amount of work you have to do to decide what to do with each request.

2) If you're going to use the Async() APIs (which you should, this will be crucial for getting the most out of the ThreadPool) then don't mix-and-match with non-Async ones. Fire off your processing to the ThreadPool with

Task.Run()

Task.Run()

and keep a reference to that

Task

Task

to make sure it eventually gets

await

await

ed, which will help you make sure that exceptions bubble out and get logged or otherwise handled, and that you can do a proper cleanup during shutdown.

3) I have no idea what you're trying to ask here.

4)

ThreadPool.QueueUserWorkItem()

ThreadPool.QueueUserWorkItem()

is probably better, so long as it gives you a way to synchronise when the work item finishes. Don't try and second-guess the efficiency and optimization of the Framework. If you think you can do something better, you'll usually be wrong, unless you have hard data to back up how your specific scenario can be optimized better. But as stated above, use

Task

Task

Async()

Async()

APIs instead.

JJakenVeina 1) Yes, that seems correct, assuming there's lots of overlap between the endpoin...

kurumiOP•10/14/23, 4:54 AM

let me rephrase p. 3: relationship 1-to-many. Where 1 is my class that should ask to execute and many are my endpoints classes. I guess, that by notify all endpoints (even if it's doesn't match user Uri) I can solve this problem, but the fault is we are wasting server resources. So is it any solution to use MediatR to execute exactly needed endpoint func (if user is on

/endpoint1

/endpoint1

only notify class of this endpoint).

p. s. the dummy idea that my friend said is store dictionary with key: endpoint Uri and value: needed executor class (but I guess it is super bad idea caz not scalable enough)

Angius•10/14/23, 4:59 AM

Back in ye olde PHP days before proper frameworks were a thing, it wasn't uncommon to roll your own front router

Angius•10/14/23, 4:59 AM

That is, you redirect all traffic to

index.php

index.php

and, depending on the requested URL, you call different other files

Angius•10/14/23, 5:00 AM

You're basically looking at doing something like that

Angius•10/14/23, 5:00 AM

Whether it'll be a dictionary, or something based on reflections and attributes, is up to you

AAngius Back in ye olde PHP days before proper frameworks were a thing, it wasn't uncomm...

kurumiOP•10/14/23, 5:00 AM

xd, so it is challenge that my teacher gave us: no Spring for Java and no ASP for C# harold

Angius•10/14/23, 5:00 AM

And depends on the complexity of the URLs

JakenVeina•10/14/23, 5:01 AM

Where 1 is my class that should ask to execute

What? What does this mean? What class is asking to execute what? We've talked about building an HTTP server, with an HttpListener, it doesn't ask to execute endpoints, it listens and is told to execute endpoints

JakenVeina•10/14/23, 5:02 AM

I like this, BTW, this is a cool challenge

JakenVeina•10/14/23, 5:02 AM

not practical, but an excellent learning experience

Angius•10/14/23, 5:03 AM

Basically, something akin to

var endpoints = new Dictionary<string, IEndpoint> {
    ["/"] = new HomeEndpoint(),
    ["/privacy"] = new PrivacyEndpoint(),
    ["/about"] = new AboutEndpoint()
};
endpoints[the_requested_url].Handle();

var endpoints = new Dictionary<string, IEndpoint> {
    ["/"] = new HomeEndpoint(),
    ["/privacy"] = new PrivacyEndpoint(),
    ["/about"] = new AboutEndpoint()
};
endpoints[the_requested_url].Handle();

interface IEndpoint
{
    void Handle();
}

interface IEndpoint
{
    void Handle();
}

kurumiOP•10/14/23, 5:03 AM

I thought that the idea is store all contexts in 1 executor function and then it will ask directly 1 endpoint func

JakenVeina•10/14/23, 5:04 AM

assuming your queries will not have any parameters, and assuming that dictionary remains static after its initial construction on startup, yes, that is a reasonable approach

JakenVeina•10/14/23, 5:05 AM

if you DO need some amount of parameter matching, I would recommend a set of

Regex

Regex

JakenVeina•10/14/23, 5:05 AM

or just one regex, if you can manage it

AAngius Basically, something akin to ```cs var endpoints = new Dictionary<string, IEndpo...

kurumiOP•10/14/23, 5:05 AM

I was thinking of that too, but imagine we have more than 10 endpoints. Not the best idea for scalable?..

JakenVeina•10/14/23, 5:05 AM

I don't see why

JakenVeina•10/14/23, 5:06 AM

again, that sounds perfectly reasonable

Angius•10/14/23, 5:06 AM

M8, you want scalable you use ASP KEKW

Angius•10/14/23, 5:06 AM

This is a school project

JakenVeina•10/14/23, 5:06 AM

the more endpoints you have, the better a Dictionary gets

JakenVeina•10/14/23, 5:06 AM

except for memory footprint

JakenVeina•10/14/23, 5:06 AM

but that's not gonna be significant compared to the lookup gains

AAngius This is a school project

kurumiOP•10/14/23, 5:08 AM

huh, yeap

my perfectionism

I guess I will store regexp as @V.EINA Jaken mentioned

JakenVeina•10/14/23, 5:08 AM

unless the

HttpListener

HttpListener

parses out the query for you

JakenVeina•10/14/23, 5:08 AM

I would do that for parsing the path out from the params

JakenVeina•10/14/23, 5:09 AM

or if you have parameters within the path

Accord•10/15/23, 5:19 AM

Was this issue resolved? If so, run

/close

/close

otherwise I will mark this as stale and this post will be archived until there is new activity.

var endpoints = new Dictionary<string, IEndpoint> { ["/"] = new HomeEndpoint(), ["/privacy"] = new PrivacyEndpoint(), ["/about"] = new AboutEndpoint() }; endpoints[the_requested_url].Handle();

❔ REST API but it is HttpListener only available

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