It turns on all the features that are necessary to build your library in such a way that it can be distributed
What does this error actually mean? Well, when the Swift compiler goes to import a module, it looks for a file called the Compiled Module for that library. If it finds one of these files, it reads off the manifest of public APIs that you can call into, and lets you use them. Now, this Compiled Module Format is a binary format that basically contains internal compiler data structures.
And since they’re just internal data structures, they’re subject to change with every version of the Swift Compiler. So what this means is that if one person tries to import a module using one version of Swift, and that module was created by another version of Swift, their compiler can’t understand it, and they won’t be able to use it.
Well, in order to solve this version lock, Xcode 11 introduces a new format for Swift Modules, called Swift Module Interfaces. And just like the Compiled Module Format, they list out all the public APIs of a module, but in a textual form that behaves more like source code. And since they behave like source code, then future versions of the Swift Compiler will be able to import module interfaces created with older versions. And when you enable Build Libraries for Distribution, you’re telling the compiler to generate one of these stable interfaces whenever it builds your framework
It turns on all the features that are necessary to build your library in such a way that it can be distributed
What does this error actually mean? Well, when the Swift compiler goes to import a module, it looks for a file called the Compiled Module for that library. If it finds one of these files, it reads off the manifest of public APIs that you can call into, and lets you use them. Now, this Compiled Module Format is a binary format that basically contains internal compiler data structures.
And since they’re just internal data structures, they’re subject to change with every version of the Swift Compiler. So what this means is that if one person tries to import a module using one version of Swift, and that module was created by another version of Swift, their compiler can’t understand it, and they won’t be able to use it.
Well, in order to solve this version lock, Xcode 11 introduces a new format for Swift Modules, called Swift Module Interfaces. And just like the Compiled Module Format, they list out all the public APIs of a module, but in a textual form that behaves more like source code. And since they behave like source code, then future versions of the Swift Compiler will be able to import module interfaces created with older versions. And when you enable Build Libraries for Distribution, you’re telling the compiler to generate one of these stable interfaces whenever it builds your framework
Before working with Windows Phone and iOS, my life involved researching VoIP. That was to build a C library for voice over IP functionality for a very popular app, and that was how I got started in open source.
The library I was working with were Linphone and pjsip. I learn a lot of UDP and SIP protocol, how to build C library for consumption in iOS, Android and Windows Phone, how challenging it is to support C++ component and thread pool in Windows Phone 8, how to tweak entropy functionality in OpenSSL to make it compile in Windows Phone 8, how hard it was to debug C code with Android NDK. It was time when I needed to open Visual Studio, Xcode and Eclipse IDE at the same time, joined mailing list and followed gmane. Lots of good memories.
Today I find that those bookmarks I made are still available on Safari, so I think I should share here. I need to remove many articles because they are outdated or not available anymore. These are the resources that I actually read and used, not some random links. Hopefully you can find something useful.
This post focuses more about resources for pjsip on client and how to talk directly and with/without a proxy server.
First of all
Here are some of the articles and open sources made by me regarding VoIP, hope you find it useful
rtpproxy: I forked from http://www.rtpproxy.org/ and changed code to make it support for IP handover. It means the proxy can handle when IP changes from 3G, 4G to Wifi and to reduce chances of attacks
Voice over Internet Protocol (also voice over IP, VoIP or IP telephony) is a methodology and group of technologies for the delivery of voice communications and multimedia sessions over Internet Protocol (IP) networks, such as the Internet
Open Source VOIP Software: this is a must read. Lots of foundation articles about client and server functionalities, SIP, TURN, RTP, and many open sources framworks
VOIP call bandwidth: a very key factor in VoIP application is bandwidth consumption, it’s good to not going far beyond the accepted limit
Routers SIP ALG: this is the most annoying, because there is NAT and many types of NAT, also router with SIP ALG
SIP SIMPLE Client SDK: introduction to SIP core library, but it gives an overview of how
microSIP: Open source portable SIP softphone for Windows based on PJSIP stack. I used to use this to test my pjsip tweaked library before building it for mobile
What is SIP: introduction to SIP written by the author of CSipSimple
Kamailio: this is the server that I used, and it plays well with lots of standard SIP clients, including pjsip. Debugging on this server was also a fun story
RTP, SIP clients and server need to conform to some predefined protocols to meet standard and to be able to talk with each other. You need to read RFC a lot, besides you need to read some drafts.
NAT solves the problem with lack of IP, but it causes lots of problem for SIP applications, and for me as well 😂
Network address translation: Network address translation (NAT) is a method of remapping one IP address space into another by modifying network address information in the IP header of packets while they are in transit across a traffic routing device
Learn how TCP helps SIP in initiating session and to turn in TCP mode for package sending
Transmission Control Protocol: The Transmission Control Protocol (TCP) is one of the main protocols of the Internet protocol suite. It originated in the initial network implementation in which it complemented the Internet Protocol (IP)
Datagram socket: A datagram socket is a type of network socket which provides a connectionless point for sending or receiving data packets.[2] Each packet sent or received on a datagram socket is individually addressed and routed
Learn about Transport Layer Security and SSL, especially openSSL for how to secure SIP connection. The interesting thing is to read code in pjsip about how it uses openSSL to encrypt messages
STUN: STUN (Simple Traversal of UDP through NATs (Network Address Translation)) is a protocol for assisting devices behind a NAT firewall or router with their packet routing. RFC 5389 redefines the term STUN as ‘Session Traversal Utilities for NAT’.
Learn about [Application Layer Gateway](http://Application Layer Gateway) and how it affects your SIP application. This component knows how to deal and modify your SIP message, so it might introduce unexpected behaviours.
This is a very common problem in VoIP, sometimes we hear voice from the other and also from us. Learn how echo is made, and how to effectively do echo cancellation
Echo and Sidetone: A telephone is a duplex device, meaning it is both transmitting and receiving on the same pair of wires. The phone network must ensure that not too much of the caller’s voice is fed back into his or her receiver
PJSIP is a free and open source multimedia communication library written in C language implementing standard based protocols such as SIP, SDP, RTP, STUN, TURN, and ICE. It combines signaling protocol (SIP) with rich multimedia framework and NAT traversal functionality into high level API that is portable and suitable for almost any type of systems ranging from desktops, embedded systems, to mobile handsets.
Mutex Locks Order in PJSUA-LIB: how multiple locks at each layer helps ensure correction and avoid deadlocks. I had lots of nightmare debugging deadlocks with pjsip 😱
Video Device API; PJMEDIA Video Device API is a cross-platform video API appropriate for use with VoIP applications and many other types of video streaming applications.
There are many SIP client for mobile and desktop, microSIP, Jitsi, Linphone, Doubango, … They all follow strictly SIP standard and may have their own SIP core, for example microSIP uses pjsip, Linphone uses liblinphone, …
Among that, I learn a lot from the Android client, CSipSimple, which offers very nice interface and have good functionalities. Unfortunately Google Code was closed, so I don’t know if the author has plan to do development on GitHub.
I also participated a lot on the Google forum for user and dev. Thanks for Regis, I learn a lot about open source and that made me interested in open source.
I don’t make any money from csipsimple at all. It’s a pure opensource and free as in speech project. I develop it on my free time and just so that it benefit users. That’s the reason why the project is released under GPL license terms. I advise you to read carefully the license (you’ll learn a lot of things on the spirit of the license and the project) : http://www.gnu.org/licenses/gpl.html To sump up, the spirit of the GPL is that users should be always allowed to see the source code of the software they use, to use it the way they want and to redistribute it.
RTP Proxy
Because of NAT or in case users want to talk via a proxy, then a RTP proxy is needed. RTPProxy follows standard and works well with Kamailio
To reduce payload size, we need to encode and decode the audio and video package. We usually use Speex and Opus. Also, it’s good to understand the .wav format
Windows Phone 8 introduces C++ component , changes in threading, VoIP and audio background mode. To do this I need to find another threadpool component and tweak openSSL a bit to make it compile on Windows Phone 8. I lost the source code so can’t upload the code to GitHub 😢. Also many links broke because Nokia was not here any more
Firstly, learn how to compile, use OpenSSL. How to call it from pjsip, and how to make it compile in Visual Studio for Windows Phone 8. I also learn the important of Winsock, how to port a library. I struggled a lot with porting openSSL to Windows RT, then to Windows Phone 8
A lot of links were broken 😢 so I can’t paste them all here.
Since pjsip, rtpproxy and kamailio are all C and C++ code. I needed to have a good understanding about them, especially pointer and memory handling. We also needed to learn about compile flags for debug and release builds, how to use Make, how to make static and dynamic libraries.
Depending on the need, we have different apps on the mac. As someone who worked mostly with development, below are my indispensable apps. They are like suits to Tony Stark. Since I love open source apps, they have higher priority in the list.
iTerm2 is a replacement for Terminal and the successor to iTerm. It works on Macs with macOS 10.10 or newer. iTerm2 brings the terminal into the modern age with features you never knew you always wanted.
iTerm2 has good integration with tmux and supports Split Panes
Term2 allows you to divide a tab into many rectangular “panes”, each of which is a different terminal session. The shortcuts cmd-d and cmd-shift-d divide an existing session vertically or horizontally, respectively. You can navigate among split panes with cmd-opt-arrow or cmd-[ and cmd-]. You can “maximize” the current pane — hiding all others in that tab — with cmd-shift-enter. Pressing the shortcut again restores the hidden panes.
A delightful community-driven (with 1,200+ contributors) framework for managing your zsh configuration. Includes 200+ optional plugins (rails, git, OSX, hub, capistrano, brew, ant, php, python, etc), over 140 themes to spice up your morning, and an auto-update tool so that makes it easy to keep up with the latest updates from the community.
I use z shell with oh-my-zsh plugins. I also use zsh-autocompletions to have autocompletion like fish shell and z to track and quickly navigate to the most used directories.
VS Code is a new type of tool that combines the simplicity of a code editor with what developers need for their core edit-build-debug cycle. Code provides comprehensive editing and debugging support, an extensibility model, and lightweight integration with existing tools.
This seems to be the most popular for front end development, and many other things. There’s bunch of extensions that make the experience to a new level.
Built by me. When developing iOS, Android and macOS applications, I need a quick way to generate icons in different sizes. You can simply drag the generated asset into Xcode and that’s it.
I built this as a native macOS app to capture screen and save to gif file. It works like Licecap but open source. There’s also an open source tool called kap that is slick.
I often need to test push notification to iOS and Android apps. And I want to support both certificate and key p8 authentication for Apple Push Notification service, so I built this tool.
FinderGo is both a native macOS app and a Finder extension. It has toolbar button that opens terminal right within Finder in the current directory. You can configure it to open either Terminal, iTerm2 or Hyper
Atom one dark theme
This is about theme. There is the very popular dracular themes, but I find it too strong for the eyes. I don’t use Atom, but I love its one dark UI. I used to maintain my own theme for Xcode called DarkSide but now I use xcode-one-dark for Xcode and Atom One Dark Theme for Visual Studio Code.
I also use Fira Code font in Xcode, Visual Studio Code and Android Studio, which has beautiful ligatures.
Chrome extensions
I use Chrome for its speed and wonderful support for extensions. The extensions I made are github-chat to enable chat within GitHub and github-extended to see more pinned repositories.
Sublime Text is a sophisticated text editor for code, markup and prose. You’ll love the slick user interface, extraordinary features and amazing performance.
Sublime Text is simply fast and the editing experience is very good. I’ve used Atom but it is too slow.
Meet a new Git client, from the makers of Sublime Text
Sublime Merge never lets me down. The source control app is simply very quick. I used SourceTree in the past, but it is very slow and had problem with authentication to Bitbucket and GitHub, and it halts very often for React Native apps, which has lots of node modules committed.
Xcode is the go to editor for iOS developer. The current version is Xcode 10. From Xcode 8, plugins are not supported. The way to go is Xcode extensions.
I have developed XcodeColorSense2 to easily recognise hex colors, and XcodeWay to easily navigate to many places right from Xcode
Do you know that questions about git get the most views on StackOverflow? I’ve searched a lot on Google how to execute certain actions with git, and this actually slowed me down a lot. There are some actions that we tend to use a lot, so it’s good to learn them. Here are my favorites, learning from friends and internet, hope you find them useful.
Before we begin, you should run git –version to check your current git version, mine is 2.12.2 as in macOS High Sierra. Here is the official git documentation, you can read details about git commands, parameters and new releases of git.
Create the branch on your local machine and switch in this branch:
git checkout -b branch_name
Create branch from commit:
git branch branch_name sha1_of_commit
Push the branch to remote:
git push origin branch_name
Rename other branch:
git branch -m old new
Rename current branch:
git branch -m new
Rename remote branch:
git branch -m old new # Rename branch locally
git push origin :old # Delete the old branch
git push --set-upstream origin new # Push the new branch, set local branch to track the new remote
Doing things in command line is cool and faster. However for viewing branches and commits, I find using a GUI client more visualizing and comfortable. You can see a list of all GUI clients here, I myself use SourceTree.
Check before you commit
We usually have some experiment code that we don’t want they to step into our commit. I usually mark my experiment with // but sometimes forget to unstage that.
Starting with 2.9, Git has improvement on its commit hook which makes it globally using hooksPath.
Firstly we nee to create a file called pre-commit, and place it into, for example, /Users/khoa/hooks:
if git rev-parse --verify HEAD >/dev/null 2>&1 then against=HEAD else # Initial commit: diff against an empty tree object against=4b825dc642cb6eb9a060e54bf8d69288fbee4904 fi
# The special marker tag to mark things which we still need to change marker="<TEST>"
# Redirect output to stderr. exec 1>&2
iftest $(git diff --cached -z $against | grep $marker | wc -c) != 0 then cat <<\EOF Error: Still has invalid debug markers in code: EOF echo `git diff --cached -z $against -G $marker` exit 1 fi
In your project, run git config core.hooksPath /Users/khoa/hooks.
