obtaining.xml

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<!DOCTYPE chapter SYSTEM "chapter.dtd">
<chapter>
  <header>
    <title>Obtaining Erlang/OTP and books/articles about it</title>
    <prepared>Matthias Lang</prepared>
    <docno></docno>
    <date>2007-09-12</date>
    <rev>1.0</rev>
    <file>obtaining.xml</file>
  </header>

  <section><title>Where can I get Erlang/OTP?</title>

    <p>
	Open Source Erlang/OTP can be downloaded from 
	<url href="http://www.erlang.org/">the open source Erlang 
	site</url>. The site provides full source code as well
	as binaries for Windows machines. This is probably the best
	place to go to make sure you're getting the latest version.
</p><p>
	
	The <url href="http://www.debian.org/">Debian Distribution</url>
	of <em>GNU/Linux</em> includes various versions
	Erlang in different releases, under <em>interpreters</em>.
</p><p>
	Precompiled ready-to-go installers for a variety of platforms
        are available from the <url href="http://cean.process-one.net/">
        Comprehensive Erlang Archive Network (CEAN)</url>. CEAN also
        provides dozens of Erlang applications.
</p><p>

	Various versions of Erlang appear on various Walnut Creek 
	FreeBSD CDs.
</p><p>
	Users within Ericsson can use Ericsson's internally supported
        version of Erlang from <url href="http://www.erlang.se/">
	www.erlang.se</url>.
</p>
  </section>

  <section><title>What's the current version of (Open Source) Erlang?</title>

	<p>R13B was released in April 2009. As further patches are
	released, the "current" version becomes R13B01, R13B02 etc.
	This curious version numbering scheme is also used on Ericsson
	mobile phones, for instance my phone is an R1F phone...</p>


	<p>Before the R13 releases, releases were named R12B-0, R12B-1,
	R12B-2 etc.

	</p><p>Major releases typically come somewhere between 12
	and 18 months apart.

	</p><p>
	Components of Erlang have their own version numbers, for
	instance the virtual machine in R7B-0 has version 5.0.1
	(yes, this is a bit confusing; 
	<seealso marker="implementations#version-table">
        see also</seealso>).
        </p>
  </section>

  <section><title> Which licence is Open Source Erlang shipped with?</title>

    <p>
	The Open Source Erlang <url 
	href="http://www.erlang.org/EPLICENSE">Licence</url> is essentially
	the Mozilla (Netscape) Public Licence with a few modifications 
	to make it compatible with Swedish law.
	</p><p>

	As far as I understand, this means you can obtain Erlang 
	for free, use it to build cool systems and sell them 
	without Ericsson coming around to charge you money.
	For an authoritative statement, you'll need a lawyer.
</p>
  </section>

  <section><title> What documentation is there for Erlang?</title>

    <p>
        The language itself is best described by the 
	<url href="http://www.erlang.org/doc/reference_manual/users_guide.html">
        Language Reference Manual</url>.</p><p>

	The documentation delivered with open source erlang
	as both man pages and <url href="http://www.erlang.org/doc.html">
	html</url> is the most up-to-date reference to both the
	OTP libraries and Erlang itself. On unix systems, the
	an easy way to read the man pages is <c>erl -man gen_tcp
	</c>.
	</p><p>

        <em>Erlang Programming (A Concurrent Approach to Software Development)
	  </em> by Francesco Cesarini and Simon Thompson is the most recent
	book about Erlang, published in 2009. You can buy it from various
	online bookstores, or directly from the 
	<url href="http://oreilly.com/catalog/9780596518189">publisher</url>.
	</p><p>

	<em>Programming Erlang: Software for a Concurrent World</em>
	(Joe Armstrong) is a book about Erlang written by one of the
	original inventors, published in 2007. You can buy it on paper
	from Amazon and other online bookstores, or directly from
	the <url href="http://pragmaticprogrammer.com/titles/jaerlang/index.html">publisher</url>.

	</p><p>
	<em>Erlang Programmation</em>(Micka&euml;l R&eacute;mond)
        is an alternative if your French is up to it, it can be 
        ordered 

        <url href="http://www.eyrolles.com/Informatique/Livre/9782212110791/livre-erlang.php">from the publisher</url> or via
	<url href="http://www.amazon.com/exec/obidos/tg/detail/-/2212110790/qid=1087192705/sr=1-3/ref=sr_1_3/102-4008653-6425766?v=glance%25s=books">
        Amazon</url>.

	</p><p>

	<em>Concurrent Programming in Erlang (2nd. Edition, 1993)</em>
	(Armstrong, Virding, Wikstr&ouml;m &amp; Williams) is only of
	historical interest. Archaeologists can download
	the <url href="http://www.erlang.org/doc.html"> first half of
	the book</url> from erlang.org.
	
        </p><p>

	Also only of historical interest: Maurice Castro's book, <url 
	href="http://www.castro.aus.net/~maurice/serc/erlbk/"
        >Erlang in Real Time (1998)</url>.
	</p>
  </section>

  <section><title> What advanced Erlang documentation is there?</title>
    <p>

	The <url href="http://www.erlang.org/download/erl_spec47.ps.gz">
	Standard Erlang</url> spec aims to define the Erlang language. 
	There is currently no compiler which actually implements everything
	exactly the way <em>Standard Erlang</em> specifies.
	This specification is quite precise; it's intended as a reference, 
	not a bedtime read! Compiler and tool implementors will find
	this useful, as will advanced Erlang programmers.

</p><p>
	<url href="http://www.it.uu.se/research/group/hipe/cerl/">Core Erlang
	</url> is an effort to define an Erlang-like language which is 
	nicer to compilers and language tools and can be automatically
	generated from Erlang. Erlang compilers from R10 onwards can
	generate Core Erlang from normal Erlang code. They can also
	generate .beam files from Core Erlang.

</p><p>
        <url href="http://forum.trapexit.org/viewtopic.php?p=44172#44172">
        The Erlang Rationale</url> is a short (13 page) discussion 
        written by one of the original authors of Erlang about why
        some parts of Erlang became the way they are. It's a work
        in progress.

</p><p>
	The proceedings from the Erlang User Conferences contain
	many interesting articles. The 
	<url href="http://www.erlang.se/euc/"> 
	proceedings</url> for each of the yearly conferences since 1999
	are online.

</p><p>
	The internals of the BEAM file format are described on
	<url href="http://www.erlang.se/~bjorn">
	Bj&ouml;rn's homepage </url>. Eventually
	this will/might include a description of the 
	virtual machine's instructions. Bj&ouml;rn also includes some
	benchmarks comparing different versions of the BEAM machine.
	You may also want to take a look at the <c>beam_lib</c>
	module.

</p><p>
	Joe Armstrong's Thesis, 
        <url href="http://www.sics.se/~joe/thesis/armstrong_thesis_2003.pdf">
	Making reliable distributed systems in the presence of software errors</url> contains a lot of interesting information, including a compact overview
        of the language, a number of case studies and some discussion of 
        the language's evolution, somewhat similar to Bjarne 
        Stroustrup's <em>Design and Evolution of C++</em>.

</p><p>
        <url href="http://www.d.kth.se/~d95-rgr/examensarbetesrapport/">
        This Masters Thesis</url> contains a good
        overview of some of Erlang's implementation aspects, including
        memory allocation (section 7).
</p><p>

        <url href="http://www.student.nada.kth.se/~d95-bka/thesis.html">
        Another Masters Thesis</url> contains a good
        overview of Erlang's distribution mechanisms (Section 5).
</p><p>
	
	Mnesia's internals are described on 
	<!-- REVISIT: erlang projects was down at last viewing, 2009-05-15 -->
	<url href="http://www.erlang-projects.org/Groups/erlang_frameworks/mnesia_internals_sli/block_11394822732946/file">
	H&aring;kan's slides</url>

</p><p>
        The <url href="http://www.cs-lab.org/papers.html"> 
	(Ex-Ericsson) computer science laboratory</url> has a collection 
	of papers about Erlang-related topics.

</p><p>
	The source-code release includes a directory with some of the
	internal build documentation in the subdirectory
	<c>erts/emulator/internal_doc/
	</c>. 

</p><p>
	<!-- REVISIT: erlang projects was down at last viewing, 2009-05-15 -->
	Erlang-projects has a <url href="http://www.erlang-projects.org/Public/documentation/serc/">collection</url> of papers written at the
	now-defunct SERC division of RMIT.

</p><p>
	The Trapexit wiki has a collection of
	<url href="http://wiki.trapexit.org/index.php/Category:HowTo">
        HowTo</url> documents showing how to do all manner of things from
        <url href="http://wiki.trapexit.org/index.php/A_fast_web_server_demonstrating_some_undocumented_Erlang_features">how to write a webserver in Erlang</url> to <url href="http://wiki.trapexit.org/index.php/Writing_an_Erlang_Port_using_OTP_Principles">how to write an Erlang Port program</url>.

</p>
  </section>

  <section><title> What documentation is there in related subjects?</title>
    <p>

	The standard text about data structures in functional languages
	is <em>Purely Functional Data Structures</em> by
	Chris Okasaki. The parts about laziness (about half of the book)
	do not apply to Erlang, but are interesting nonetheless. 
	An <url href="http://www-2.cs.cmu.edu/~rwh/theses/okasaki.pdf">early 
	version of the book</url> is available online, the book itself is 
	available from many online booksellers.

</p><p>
	<em>Structure and Interpretation of Computer Programs</em>
	is a standard introductory text to functional programming. It is
	available both on paper and
	<url href="http://mitpress.mit.edu/sicp/">online</url>

</p><p>
	(Suggestions for further books to for this section are welcome.
	Mail the maintainer: <url href="mailto:matthias@corelatus.com"> matthias@corelatus.com</url>.)

</p>
  </section>

  <section><title>Is there public CVS/Git/your-favourite-vcs repository for the Erlang source?</title>

    <marker id="repositories"/>

    <p>As of R13B03 (November 2009), there is
      an <url href='http://github.com/erlang/otp'>official Git
      repository</url> maintained (daily!) by the Erlang/OTP
      group. There is also
      an <url href='http://github.com/mfoemmel/erlang-otp'> unofficial
      repository</url> which includes history before the R13B03
      release.
    </p>

    <p>
        The HIPE group provide public read-only CVS access to their
        branch, which closely follows the OTP tree, of the Erlang
        source. <url href="http://www.it.uu.se/research/group/hipe/hacking/cvs.shtml">Instructions
        are here</url> or you can just check out like this:
    </p>
    <pre>
    cvs -d :pserver:guest@cvs.srv.it.uu.se:/hipe co otp
    </pre>

    <p>
    And there's an unofficial <url href="https://code.launchpad.net/erlang">
    Bazaar repository</url> of the same thing.
    </p>
    
  </section>

  <section><title>How can I contribute to Erlang?</title>

    <p>
When you write Erlang code you want to share, there are quite a number of 
ways to share it. The place to announce such things is the Erlang Questions 
mailing list, or, in the case of patches, the Erlang Patches mailing list.
Where you put the actual code is up to you.

</p><p> 
If your code is a modification to an existing part of OTP,
attach a patch to your post to the erlang-patches mailing
list. There's some useful general advice on making and sharing patches
<url
href="http://www.kegel.com/academy/opensource.html">here</url>.  The
OTP group is quite conservative about including such code, especially
if it requires new test cases to be written, so expect it to take a
long time (months or years) for your code to find its way into the
official distribution.  
</p>

    <p>
If your code is a new application or library, some common ways of 
distributing it are:
</p>

    <list>
      <item><p>Checking your code into the 
              <url href="http://jungerl.sourceforge.net">jungerl</url>
 </p></item>

      <item><p>Starting your own 
              <url href="http://sourceforge.net/">sourceforge</url>
		or <url href="http://github.com/">github</url>
	      project </p></item>

      <item><p>Putting the code on a personal homepage </p></item>

      <item><p>Getting your code <url href="http://cean.process-one.net/contrib/packaging-guide.txt">packaged into the CEAN</url></p></item>
    </list>
  </section>
  <section>
    <marker id="eeps"/> 
    <title>How can I propose changes to the language itself?</title>
    <p>
        Even though Erlang is a fairly mature language with a large
        established code-base, changes and enhancements are still
        being incorporated. There is a mechanism
        called the <url
        href="http://user.it.uu.se/~pergu/eep/eep-0001.html">Erlang
        Enhancement Proposal</url> which formalises the process.

</p>
  </section>

  <section>
    <title>Where is Erlang discussed in the real world?</title>

    <section>
      <title>Conferences</title><p>

	Every year (in September or October) there is an <em>
	Erlang user conference</em>. The<url href="http://www.erlang.se/euc/">
	proceedings</url> are archived. 
</p><p>
        In June 2008 and April 2009, the first ever <em>commercial</em> Erlang
	conferences were held in London and San Francisco. This is now 
	a regular event with further <url href="http://www.erlang-exchange.com/">Erlang Exchange
        </url> events planned.
</p><p>        
        Academic conferences about 
	functional programming are also attended by a few Erlang users.
	The <url href="http://pli2002.cs.brown.edu/">
	Principles, Logics, and Implementations of High-Level Programming Languages</url> usually includes an Erlang workshop. The 
        <url href="http://www.erlang.se/workshop/">ACM Sigplan</url>
        Conference includes an Erlang workshop too.
</p>
  </section>
  <section>
     <title>Erlounge and User Groups</title><p> Every so often,
        someone puts out an invitation on erlang-questions to
        informally discuss Erlang over a few beers. Past Erlounges
        have been in Sweden (Stockholm), Scotland, the USA (Atlanta,
	New York, Chicago, North
        Carolina, Schaumburg, Seattle, SF Bay area,
        Arlington, Washington DC), France (Paris), China (I can't read the
        characters which described the location), Italy, Germany (Aachen),
        Poland (Krakow), New Zealand (Wellington) and others. There's a
        <url href="http://www.trapexit.org/ErlangUserGroups">Trapexit</url>
        page listing known usergroups.</p>
  </section>
  </section>

  <section>
    <marker id="#mailing-lists"/>
    <title>Where is Erlang discussed online?</title>

    <p>

	There are several 
        <url href="http://www.erlang.org/mailman/listinfo">
	mailing lists devoted to Erlang</url>:
	</p>

    <section>
      <title>erlang-questions</title><p>

		This is intended for general 
		discussion about Erlang. Anyone can send
		mail to <url href="mailto:erlang-questions@erlang.org">
		erlang-questions@erlang.org</url>, and anyone can 
		<url href="http://www.erlang.org/mailman/listinfo">
                subscribe</url>.</p>
    </section>

    <section>
      <title>erlang-announce</title><p>
	
		This list carries announcements
		about new releases of Erlang, patches, etc.
		All posts to <em>erlang-announce</em> also appear
		in <em>erlang-questions</em>.</p>
    </section>

    <section>
      <title>erlang-patches</title><p>
		This list is for patches to the Erlang distribution.
		At the time of writing, it is not archived.</p>
    </section>

    <section>
      <title>erlang-bugs</title><p>
		This list is for bug reports.</p>
    </section>

  <section>
    <marker id="forums"/>
    <title>Web forums and mailing list archives</title>
    <p>

	The erlang-questions list is
	<url href="http://www.erlang.org/pipermail/erlang-questions/">
	archived on the Erlang website</url>. 

        </p><p>
        The GMANE news/mail gateway acts as both an archive and a
        forum-style way of using the mailing list. It has 
        <url href="http://news.gmane.org/gmane.comp.lang.erlang.general">
	Erlang Questions</url> and
	<url href="http://news.gmane.org/gmane.comp.lang.erlang.patches">
	Erlang Patches</url>. 

        </p><p>
        The <url href="http://www.trapexit.org/">trapexit</url> site
        also has a forum interface to the mailing list.
</p>
  </section> 


    <section>
      <title>IRC channel</title><p>
        There's an IRC channel, #erlang, on irc.freenode.net</p>
    </section>

  </section>

  <section><title>Are there any websites apart from erlang.org?</title>

    <p>
	<!-- REVISIT: erlang projects was down at last viewing, 2009-05-15 -->
	<url href="http://www.erlang-projects.org/">Erlang-projects</url>
	aims to track Erlang use in projects.

</p><p>
        <url href="http://trapexit.org">trapexit</url> is a grab-bag
        of erlang news, erlang-related forums and a bidirectional 
        forum/mailing list gateway.
 
</p><p>
        <url href="http://planeterlang.org">planet erlang</url> aggregates
        a couple of dozen erlang-related RSS feeds.

</p><p>
	The <url href="http://www.erlang.se">Ericsson site</url> for 
	all matters related to Ericsson-internal use of Erlang
	also contains information about internal training and consulting.
      
</p><p>
	The mozilla dmoz has a 
	<url href="http://dmoz.org/Computers/Programming/Languages/Erlang/">
	directory of Erlang links</url>.
</p>
  </section> 

  <section><title>Where can I find Erlang programmers/employers?</title>
    <p>
	Posting a short note to <seealso marker="#mailing-lists">
	erlang-questions@erlang.org</seealso> is probably a good start, 
	especially if the subject-line clearly identifies the post as 
	a job request/advert. Some consulting companies have posted 
	there in the past.
	</p><p>

	Erlang-solutions.com have a 
	<url href="http://www.erlang-solutions.com/jobs.html">
	recruitment page
	</url>
	</p><p>

	Several consultant groups have Erlang-certified people in
	Sweden, including 
	<url href="http://www.enea.se/"> ENEA data</url> and
	<url href="http://www.erlang-services.com/">Sj&ouml;land &amp; Thyselius</url>.
        
	<url href="http://www.erlang-solutions.com/">erlang-solutions.com 
	</url> take assignments worldwide.

        <url href="http://www.process-one.net/en/services/">
         Process-one</url> are based in France.

	</p><p>	
	If you want to be listed here, send some mail to
	<url href="mailto:matthias@corelatus.com">
	matthias@corelatus.com</url>.
	</p><p>

	Kontakten (Contact), an Ericsson-internal newspaper, may
	also be useful as it carries many job ads. 
        </p>
  </section>
</chapter>