implementations.xml

<?xml version="1.0" encoding="iso-8859-1" ?>
<!DOCTYPE chapter SYSTEM "chapter.dtd">
<chapter>
  <header>
    <title>Implementation and Ports of Erlang</title>
    <prepared>Matthias Lang</prepared>
<docno></docno>
<date>2007-09-12</date>
    <rev>1.0</rev>
    <file>implementations.xml</file>
  </header>

<section>
    <marker id="implementations"/>
    <title>What Production-quality implementations of Erlang are there?</title>

	<list>
	<item><p> <url href="http://www.erlang.org/"> Open Source 
	Erlang </url>
	  is the most popular implementation.
	  It is built from the same source tree as the commercial
	  version of Erlang. You can use Open Source Erlang to build
	  commercial products without having to pay royalties or licence
	  fees to Ericsson.
	<marker id="commercial-erlang"/>
        </p></item>


	<item><p> <url href="http://www.erlang.se/">
		Ericsson's Commercial Erlang</url>. This is essentially 
		the same as Open Source Erlang. The main differences are:
               </p>

		<list>
		<item><p>Commercial Erlang comes with a support agreement
                 </p></item>
	
		<item><p>The OTP team go to greater lengths 
			to test the commercial release, so you 
			get a more stable product. Similarly, they
			make the transition between versions smoother.
                 </p></item>

		<item><p>The commercial version includes some
			encryption-related code which cannot be 
			provided in the open source release for legal reasons.
                 </p></item>

		<item><p>The commercial release does <em>not
			</em> contain applications which are
			considered experimental or unstable.
                 </p></item>

		</list>
             </item>
	</list>

</section>
<section><title>What Experimental and Research Implementations are there?</title>

	<list>

	<item><p><url 
		href="http://www.it.uu.se/research/group/hipe"> 
		High Performance Erlang</url> (HIPE). 
		HIPE is an in-progress project to create a faster Erlang
		by compiling to native code. Since R8A, the HIPE compiler
		is tightly integrated with the normal BEAM system; if
		you have downloaded open source erlang, then you also have
		HIPE. A <url href="http://www.erlang.se/euc/01/kostis2001/sld001.htm">presentation at the EUC 2001</url> described how to use it.</p></item>

	<item><p>
		<url href="http://www.iro.umontreal.ca/~etos/"> 
		Erlang to Scheme Compiler</url> (ETOS). 
		ETOS is another research project to compile Erlang 
		programs to native code by first translating the
	        program into scheme. They have some impressive benchmarks.
		ETOS is no longer under active development.</p></item>

	<item><p>
		Geoff's Erlang (GERL) supported a subset of the Erlang 
                language. GERL compiled to native code via C. GERL has 
		fallen into disuse.</p></item>

	<item><p><url 
		href="http://www.adfa.edu.au/~lpb/research/sserl/">
		Safe Erlang</url>,
		which is a prototype made by extending an older version
		of Ericsson's implementation, is intended for
		applications where Erlang nodes must cooperate with
		other Erlang nodes which are not trusted. Safe Erlang
                is no longer under active development.</p></item>

	</list>

</section>
<section>
    <marker id="version-table"/>
    <title> Which version of Erlang am I running?</title>
    <p>
        Starting with R13A, the message you see when you start
        Erlang actually tells which release you are running:
    </p>

	<pre>
	Erlang R13B (erts-5.7.1) [smp:4:4] [rq:4] [async-threads:0] [kernel-poll:false]

	Eshell V5.7.1  (abort with ^G)
	</pre>

    <p> 
	From Erlang code, in recent releases, 
	call <c>erlang:system_info(otp_release)</c>
	to find out which release you are running.
    </p>
    <p>
	In earlier releses, the message you saw when you
	started Erlang didn't show you the version number of
	OTP:
</p>
	<pre>
	Erlang (BEAM) emulator version 5.1.1 [source]

	Eshell V5.1.1  (abort with ^G)
	</pre>

<p>
        The start script revealed some more information:
</p>

        <pre>
        Eshell V5.3.6.3  (abort with ^G)
        1> init:script_id().
        {"OTP  APN 181 01","R9C"}
        </pre>

</section>
<section><title> What operating systems does Erlang run on?</title>
<p>

	Erlang runs on most unix and unix-like systems and on the 
	currently popular flavours of windows. Ericsson 
	have compiled it for
</p>

	<list>
	<item><p> Solaris (including 64 bit)</p></item>
	<item><p> BSD</p></item>
	<item><p> Linux</p></item>
	<item><p> OSX</p></item>
	<item><p> TRU64</p></item>
	<item><p> Windows NT/2000/2003/XP/Vista</p></item>
	<item><p> VxWorks</p></item>
	</list>

        <p>

	There are reports on the mailing list of other people 
        compiling it successfully IRIX, along with reports of
        Erlang running on less usual systems such as iPhones, Xboxes
        Tilera 64-core CPUs and many embedded systems.
	</p><p>

</p></section>
<section><title> What implementations of the Erlang Virtual Machine are there?</title>
<p>

	Almost everyone uses "the new BEAM", where BEAM stands
	for Bogdan/Bj&ouml;rn's Erlang Abstract Machine. This is
	the virtual machine supported in the commercial release.
	</p><p>

	The other virtual machines are of mostly historical interest:
</p>
	<section>
	<title>JAM</title><p>

		This was the original Erlang virtual machine,
		  inspired by the (Prolog) WAM. JAM stands for
		  "Joe's Abstract Machine".</p>

	</section>
	<section>
	<title>old BEAM</title><p>

		This was an attempt to compile Erlang
		to C, and then compile the C to native code. It was
		abandoned after benchmarking showed that the resulting
		code was only faster than VM-based Erlang for small programs.
</p>
	</section>

</section>
<section><title>Is there an unofficial port for...?</title>
<p>

	<em>MacOS X</em>: Releases since R9B compile on
		MacOS X.
		</p><p>

	<em>QNX</em>: Vlad Dumitrescu has looked
		at porting to QNX. If you're interested, ask on the
		erlang mailing list.</p><p>

	<em>VxWorks</em>: VxWorks support is 
		included in the standard distribution.  </p><p>

</p></section>
<section>
    <marker id="cygwin-cross"/>
    <title>Can Erlang be compiled under Microsoft Windows?</title>
<p>

	There is a README.win32 file at the top of the source code
	distribution which explains how to do this.

</p></section>

<section><title>Can Erlang be cross compiled?</title>
<p>
  From release R13B04 (released February 2010) onwards, the standard
  Erlang/OTP distribution includes support and documentation for cross
  compiling. This is described in the INSTALL-CROSS.md file at the
  top of the Erlang source, available from the
  <url href='http://erlang.org/download.html'>downloads page</url>.
</p>

<p>
  Releases <em>prior</em> to R13B04 can also be cross-compiled 
  with a moderate amount of effort. There's a fairly
  <url href='http://www.trapexit.org/Cross_compiling'>
    detailed writeup</url> on the trapexit wiki which covers
  cross compiling between linux systems.
</p>
</section>

<section><title>Is Erlang small enough for Pocket PCs?</title>
<p>

        Various people on the erlang-questions mailing list have reported
        Erlang running on pocket PCs, including the 
	<url href="http://dynamism.com/sl-c3000/main.shtml">Sharp Zaurus</url>.

</p></section>
<section><title>Is Erlang small enough for embedded systems?</title>
<p>

	Rule of thumb: if the embedded system can run an
	operating system like linux, then it is probably possible
	to get current implementations of Erlang running on it 
	with a reasonable amount of effort. 

	Getting Erlang to run on, say, an 8 bit CPU with 32kByte of
	RAM is not feasible.

	People successfully run the Ericsson implementation of
	Erlang on systems with as little as 16MByte of RAM. It 
	is reasonably straightforward to fit Erlang itself into 
	2MByte of persistant storage (e.g. a flash disk).
	</p><p>

	A 2MByte stripped Erlang system can include the
	beam emulator and almost all of the stdlib, sasl,
	kernel, inets and runtime_tools libraries, provided
	the libraries are compiled without debugging information
	and are compressed:
	</p>

	<code>
	compile:file("foo", [compressed,no_debug_info]).
	</code>

	<p>
	This can be automated by editing otp.mk.in and adding
	<c>+compressed +no_debug_info</c> 
	to the erlang compiler options and then rebuilding all the libraries.
</p>

</section>
</chapter>