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Pubnub C-core for the OpenSSL library/platform

This is the part of C-core for the OpenSSL library/platform. OpenSSL is portable across POSIX and Windows, so the same code is used on all and thus we deem OpenSSL a "library/platform".

Unfortunately, OpenSSL portability is only on the source level and only for the communication functions. There are some "peripheral" differences which we'll explore below.

Pubnub OpenSSL on POSIX

OpenSSL doesn't cover threads, so there is some POSIX-specific code for pthreads. There is a sample Makefile (, which will build sample programs on POSIX:

  • pubnub_sync_sample: a "walk-through" of the "sync" interface (API)
  • pubnub_callback_sample: a "walk-through" of the "callback" interface (API)
  • cancel_subscribe_sync_sample: an example how to cancel a subscribe loop safely, using the "sync" interface
  • subscribe_publish_callback_sample: an example of how to have one outstanding publish and one outstanding subscribe transaction/operation at the same time, using the "callback" interface.
  • pubnub_console_sync: a simple command-line Pubnub console, using the "sync" interface
  • pubnub_console_callback: a simple command-line Pubnub console, using the "callback" interface

During the build, two (static) libraries will be created:

  • pubnub_sync.a: library for the "sync" interface
  • pubnub_callback.a: library for the "callback" interface

You are free to use these libraries in your projects, but keep in mind that they are configured for the purposes of the samples. Please check if those are right for you before using them.

The sources of the samples are in ../core/samples, and for the console in ../core/samples/console, as they are portable across all or most hosted platforms (POSIX, Windows...).

So, to build the samples, just run:

make -f

The only requirement / prerequisite of this Makefile is that you have an OpenSSL package installed, which should be true for most modern POSIX systems. If that's met, it should just build with the default C compiler. To use a compiler of your choice (rather than the default one), say, clang, run:

make -f CC=clang

Build without the proxy support

To build without the proxy support, pass USE_PROXY=0 to Make, like:

make -f USE_PROXY=0

Of course, if you have previously done a build, you will probably want to first clean up the artifacts of that previous build by invoking the clean target, like:

make -f clean

Pubnub OpenSSL on Windows

OpenSSL doesn't cover threads, so there is some Windows-specific code.

But, the biggest issue is that OpenSSL is not a part of any Windows installation per se. Actually, a typical Windows computer has dozens of OpenSSL libraries used by various programs. We provide one solution for this in our sample Makefile ( as described below.

You should decide what OpenSSL you want to compile & link against. To do that, pass the path of your OpenSSL of choice as macro OPENSSLPATH to nmake. We have found that "Shinning Light Productions" OpenSSL "distribution" (could be found here at the time of this writing) works fine.

For example, the default install directory of the "Shinning Light Productions" OpenSSL "distribution" for 32-bit OpenSSL for Windows is c:\OpenSSL-Win32, so to use that, you would:

nmake -f OPENSSLPATH=c:\OpenSSL-Win32

If you don't pass OPENSSLPATH, it will use a default, which might not be good for you, so please check the default in before invoking nmake without setting OPENSSLPATH.

We expect that the OPENSSLPATH has two sub-directories:

  • include: with the OpenSSL include files
  • lib: with OpenSSL (import) library files

In general, this should work with both import library files (for DLLs) and static libraries, but that depends on your OpenSSL of choice. The important thing here is that if you use import libraries, you will have to distribute the DLLs that are a part of your OpenSSL with your applications.

The sample Makefile ( will build the same sample programs on Windows as are built on POSIX (the executables just have .exe extension on Windows). It will also build the same static libraries (but they will have .lib extension on Windows).

The sample Makefile is designed to work with MS Visual Studio compilers (MSVS 2008 or newer should work fine). Rewriting it to use some other compiler should not be too hard, mostly would involve changing the compiler switches. But, if you have a compiler that supports MSVC switches (like some Clang "distributions"), you should be able to use it instead of the MSVC standard cl, like:

nmake -f CC=clang-cl


We have not tested Pubnub OpenSSL on OSX yet.

Makefile remarks

The Makefiles are designed to be minimal and illustrate what modules you need and what #defines and compiler/link options, to build C-core. It is not designed to be just copy-pasted into a production Makefile, because that is pretty much impossible - there are way too many ways to "make a Makefile", we can't cover them all.


Since C-core is designed to have low footprint, the question of "how big is it" often comes up.

We present some numbers here, but, please keep in mind that these are volatile, because they depend on:

  1. C-core itself, which changes with time
  2. your usage of the C-core
  3. your compiler and its version
  4. the C standard library you use and its version
  5. the compiler options you pass to compiler (foremost, optimization, but many others too)

So, the number can only give you some idea, and are not to be taken for granted.

Linux 64-bit, taken on 2017-05-03

These are the numbers gotten with the makefile, with a GCC 4.8.4 on Linux Mint 17 (based on Ubuntu 14.04) - using it's "native" GlibC and OpenSSL.

OOB - with proxy support

File size [KB]
pubnub_callback.a 1438
pubnub_sync.a 1288
pubnub_callback_sample executable 348
stripped pubnub_callback_sample 88
pubnub_sync_sample executable 381
stripped pubnub_sync_sample 80

Without proxy support

This needed slight changes in the makefile (define PUBNUB_PROXY_API to 0 and remove the proxy modules from the libraries):

File size [KB]
pubnub_callback.a 1181
pubnub_sync.a 1034
pubnub_callback_sample executable 339
stripped pubnub_callback_sample 71
pubnub_sync_sample executable 302
stripped pubnub_sync_sample 62
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