PragProg Customers

Programming WebRTC: How to configure CORS for the signaling server

huynh

huynh

Programming WebRTC: How to configure CORS for the signaling server

@karlstolley

I want to run the signaling server and the front-end (e.g., basic_p2p app) on separate ports.

From the client side, I get this “CORS missing allow origin” when connecting to the server.
How to solve that issue?

What I tried so far (and that didn’t work):

// server.js
const cors = require("cors");
const app = express();
app.use(cors());
1 comment
#question/book-programming-webrtc
0 294 1

Marked As Solved

karlstolley

karlstolley

Author of WebRTC: Build Real-Time Web Applications in the Browser

Hi Huynh!

There’s a couple of ways to handle this. One would be to worry about CORS only on the socket server. Have a look at Socket.io docs at Handling CORS | Socket.IO

Or, to continue your method of working directly with Express, have a close look at their documentation, including Express cors middleware

If you’re not yet skilled with using a tool like curl, that will help you determine the headers coming back from both your app and signaling servers, and help you figure out where additional adjustments or configuration is needed.

Post #2

Where Next?

View thread on forum
View Programming Webrtc's book portal
Post errata for this book
Post a suggestion for this book
Post a question about this book
Post a review about this book
question
Home PragProg Customers
#question/book-programming-webrtc
0 294 1
Last post

Popular Pragmatic Bookshelf topics Top

iPaul
PragProg Customers

The Definitive ANTLR 4 Reference: Program deprecation warning
page 37 ANTLRInputStream input = new ANTLRInputStream(is); as of ANTLR 4 .8 should be: CharStream stream = CharStreams.fromStream(i...
#errata/book-the-definitive-antlr-4-reference
4 987 0
New
yulkin
PragProg Customers

Programming Flutter: Image.toByteData() does not exist (page40)
your book suggests to use Image.toByteData() to convert image to bytes, however I get the following error: "the getter ‘toByteData’ isn’t...
/book-programming-flutter#question
1 4102 2
New
mikecargal
PragProg Customers

Hands-On Rust: Wrong multiplier for 8x8 console in main.rs
Title: Hands-On Rust (Chap 8 (Adding a Heads Up Display) It looks like ​.with_simple_console_no_bg​(SCREEN_WIDTH*2, SCREEN_HEIGHT*2...
#errata/book-hands-on-rust
9 2026 5
New
jdufour
PragProg Customers

The Cucumber for Java Book:
Hello! On page xix of the preface, it says there is a community forum "… for help if your’re stuck on one of the exercises in this book… ...
#question/book-the-cucumber-for-java-book
3 1143 1
New
alanq
PragProg Customers

Modern Front-End Development for Rails: Can't get TURBO_STREAM format in some cases
This isn’t directly about the book contents so maybe not the right forum…but in some of the code apps (e.g. turbo/06) it sends a TURBO_ST...
#question/book-modern-front-end-development-for-rails
1 1386 7
New
leonW
PragProg Customers

Python Testing with pytest, Second Edition: File not Found Error (page 43)
I ran this command after installing the sample application: $ cards add do something --owner Brian And got a file not found error: Fil...
#errata/book-python-testing-with-pytest-second-edition
5 4391 7
New
oaklandgit
PragProg Customers

Hands-on Rust: Failed to Load Texture error (page 121)
Hi, I completed chapter 6 but am getting the following error when running: thread 'main' panicked at 'Failed to load texture: IoError(O...
/book-hands-on-rust
2 1310 3
New
ggerico
PragProg Customers

Programming Machine Learning: some plot files are throwing error
I got this error when executing the plot files on macOS Ventura 13.0.1 with Python 3.10.8 and matplotlib 3.6.1: programming_ML/code/03_...
#question/book-programming-machine-learning
1 3055 5
New
bjnord
PragProg Customers

Hands-on Rust: Chapter 3: Can't get first hello to run
Hello @herbert ! Trying to get the very first “Hello, Bracket Terminal!" example to run (p. 53). I develop on an Amazon EC2 instance runn...
#question/book-hands-on-rust
0 1147 2
New
SlowburnAZ
PragProg Customers

Machine Learning in Elixir:Error installing EXLA dependency - Page 25
Getting an error when installing the dependencies at the start of this chapter: could not compile dependency :exla, "mix compile" failed...
#errata/book-machine-learning-in-elixir
1 1159 10
New

Other popular topics Top

PragmaticBookshelf
Backend>Learning Resources

Testing Elixir
Write Elixir tests that you can be proud of. Dive into Elixir’s test philosophy and gain mastery over the terminology and concepts that u...
pragprog.com
#pragprog/elixir#published-book/book-testing-elixir
33 5004 8
New
Rainer
Community>Journals

Programming Erlang Book Club
My first contact with Erlang was about 2 years ago when I used RabbitMQ, which is written in Erlang, for my job. This made me curious and...
/erlang/book-programming-erlang-2nd-edition#book-club
195 6815 95
New
AstonJ
Backend>Chat

Rails console using 100% CPU in dev (fix)
If you are experiencing Rails console using 100% CPU on your dev machine, then updating your development and test gems might fix the issu...
/ruby/rails
3 4188 3
New
DevotionGeo
General Dev>Dev Chat

The V Programming Language
The V Programming Language Simple language for building maintainable programs V is already mentioned couple of times in the forum, but I...
#programminguages/v
21 13874 7
New
AstonJ
General Dev>Hardware

CharaChorder - type at the speed of thought?
Saw this on TikTok of all places! :lol: Anyone heard of them before? Lite:
/keyboards#charachorder
13 4703 4
New
PragmaticBookshelf
Community>In The Spotlight

Spotlight: Mike Riley (Author) Interview and AMA!
Author Spotlight Mike Riley @mriley This month, we turn the spotlight on Mike Riley, author of Portable Python Projects. Mike’s book ...
#author-spotlight/python#iot/book-portable-python-projects#internet-of-things
62 7035 19
New
PragmaticBookshelf
Community>In The Spotlight

Spotlight: Peter Ullrich (Author) Interview and AMA!
Author Spotlight: Peter Ullrich @PJUllrich Data is at the core of every business, but it is useless if nobody can access and analyze ...
/elixir/phoenix/book-building-table-views-with-phoenix-liveview
72 4765 21
New
First poster: AstonJ
General Dev>In The News

Jan: An open source alternative to ChatGPT that runs on the desktop
Jan | Rethink the Computer. Jan turns your computer into an AI machine by running LLMs locally on your computer. It’s a privacy-focus, l...
jan.ai
#desktop#chatgpt
4 5652 4
New
NewsBot
Backend>Official News

Node.js v22.14.0 released!
Node.js v22.14.0 has been released. Link: Release 2025-02-11, Version 22.14.0 'Jod' (LTS), @aduh95 · nodejs/node · GitHub
github.com
/nodejs#official-news
0 4251 0
New
Margaret
Community>In The Spotlight

AMA with: Mark Volkmann (codebar Winter Lit Fest)
Ask Me Anything with Mark Volkmann @mvolkmann On February 24 and 25, we are giving you a chance to ask questions of PragProg author M...
/book-server-driven-web-apps-with-htmx#codebar-spotlight
37 3100 20
New
Back to top

Latest in Programming WebRTC

Programming WebRTC Portal ❯

PragProg Customers

Pragmatic Bookshelf PragProg Customers ❯

Latest on Devtalk

Devtalk ❯

We ❤️ helpful members!

We reward our most helpful members via our MOTM scheme - by giving away a whopping 25 books per year!

Member of the Month

Devtalk Sponsors

Pragmatic Bookshelf

Practical resources that improve the lives of professional developers.

Erlang Solutions

We build trusted fault-tolerant systems that scale to billions of users.

Honeybadger

Real-time error tracking, performance insights, and observability for devs.

EEF

Supporting innovation across the BEAM ecosystem.

coders51

We build reliable cloud platforms for business-critical systems.

Manning Publications

Develop your skills with books, videos, and courses.

AppSignal

Catch errors, track performance, monitor hosts and more.

WyeWorks

Enabling companies to succeed by building software people love.

Pragmatic Studio

Courses that move you from confusion to "Aha, now I get it!"

View all our sponsors ❯

Categories:

Sub Categories:

Popular Portals

Devtalk Sponsors

Pragmatic Bookshelf

Practical resources that improve the lives of professional developers.

Erlang Solutions

We build trusted fault-tolerant systems that scale to billions of users.

Honeybadger

Real-time error tracking, performance insights, and observability for devs.

EEF

Supporting innovation across the BEAM ecosystem.

coders51

We build reliable cloud platforms for business-critical systems.

Manning Publications

Develop your skills with books, videos, and courses.

AppSignal

Catch errors, track performance, monitor hosts and more.

WyeWorks

Enabling companies to succeed by building software people love.

Pragmatic Studio

Courses that move you from confusion to "Aha, now I get it!"

View all our sponsors ❯

We're in Beta

About us Mission Statement See our Roadmap