Highlights
Erlang 5.0/OTP R7B

This document points at the most important improvements in Erlang 5.0/OTP R7B. For more detailed information, please check the release notes for the respective applications.

General

Some of the major new features in this version of Erlang/OTP are:

• The bit syntax, a language addition which can be used to construct binaries and to match binary patterns.
• The new CORBA services cosNotification and cosTime.
• The new very capable cross reference tool Xref.
• The new application Comet which makes it possible to call COM objects from Erlang on the Windows platform.
• A new interopability guide whose purpose is to give the reader an orientation of the different interoperability mechanisms that can be used when integrating a program written in Erlang with a program written in another programming language, from the Erlang programmer's point of view.

Note also that the Jive application has now been removed.

ERTS-5.0.1

• Several changes has been made to the garbage collector and internal memory allocation routines to reduce memory consumption and memory fragmentation.
• The bit syntax, a language addition for constructing and matching binaries. For more infomation, see Extensions to Erlang. Also, the handling of small binaries (up to 64 bytes) has been optimized, as well as splitting of binaries.
• Call tracing is greatly improved. It is now possible to trace local function calls (and calls to local functions) set up with the erlang:trace_pattern BIF. Trace compilation for local call is no longer needed.
• There is now support for operating system threads in drivers. The file driver has been modified to make use of this, which means that lengthy file operations no longer cause everything on the node to pause. Currently, only supported on Solaris and Windows. The number of threads in the thread pool can be set with the emulator system flag -A. The default number of threads is 0, which means that this feature is turned off. The number of threads in a node can be obtained by the call erlang:info(thread_pool_size).
• The BIF erlang:monitor(process,Proc) has been extended to accept named processes, local and remote. See the documentation for erlang:monitor/2 and erlang:demonitor/1.
• The inet driver (inet_drv, i.e the driver for (TCP&UDP)/IP) has been replaced, as well as a lot of supporting Erlang code in the Kernel application. The new code eliminates one data relay process per socket and thereby gives a throughput boost.
• The Erlang emulator now uses a 2 bit tag scheme internally. This change is not visible at the language level, but it means that the Erlang emulator can now address the entire 4Gb address space (OTP R6 could only address 1Gb).

IC-4.0.5

• Limited support for multiple file module definitions.
  The current version supports multiple file module definitions for all backends except the C oriented backends.
• The following new datatypes are now handled by IC:
  • long long
  • unsigned long long
  • wchar
  • wstring

Kernel-2.6.1

• On Unix, os:cmd/1 previously used a dedicated subprocess, which meant that calls to os:cmd/1 were serialized. This is no longer the case.
• The gen_ family (mainly gen_server and gen_fsm) and rpc has been rewritten to use the new BIF erlang:monitor/2 as much as possible. This should improve performance and remove some possibilities of hanging gen_server calls. In particular, gen_server:multi_call/2..4 and rpc:multi_server_call/2,3 should now never hang, at least not when all nodes are of this release.
  See also the documentation for gen_server and rpc.
• The inet driver (inet_drv, i.e the driver for (TCP&UDP)/IP) has been replaced, as well as a lot of supporting Erlang code in the Kernel application. The new code eliminates one data relay process per socket and thereby gives a throughput boost.

STDLIB-1.9.1

• The win32reg module has now been documented and made official. The module makes it possible to access and manipulate the registry on Windows platforms.
• Calls using gen_server, gen_fsm and gen_event to a process on another node no longer hang indefinitely if the timeout is infinity and the process doesn't exist. The exit reason in that case is noproc (for local processes, this change was made already in OTP R5).
• The new module beam_lib reads data from BEAM files.

Appmon-2.0.1

• There is now an Appmon User's Guide.
• The main window is now similar to that of the other tools, showing only one node at a time.

Asn1-1.2.9.3

• The ASN.1 language feature COMPONENTS OF is now implemented.
• The encoding and decoding of ENUMERATED and INTEGER with NamedNumbers is made more efficient and thus faster in runtime.
• The compiler now also supports AUTOMATIC TAGS for BER (previously only for PER).

Comet-1.0

Comet is a new application.

Comet, a COM client for Erlang, is a way to call any COM-service in Windows from an Erlang program. It's a combination of a gen_server and a port program (or port driver) that enables Erlang programs to call almost any COM-server.

Comet uses a gen_server in the module erl_com, together with a port program (or port driver), to call COM-servers. Both the late-binding interface IDispatch and early-binding virtual interfaces can be used. Erlang types are converted to COM types and parameters are returned.

COM stands for Component Object Model, (or sometimes Common Object Model), and is MicroSoft's technique for component-based programming. It allows programs on Windows systems to call other programs and libraries across language boundaries. It is a competitor to Corba, but has other functionality too.

COM is available on all 32-bit Windows systems, such as NT 4, Windows 95,Windows 98 and Windows 2000. Comet can be used on any of these.

With Comet, an Erlang application can use (almost) any COM-service on
Windows from Erlang. Examples of what can be done include:

• Opening webpages with Internet Exporer (or Netscape)
• Reading and writing data from Excel Worksheet
• Reading and writing from Word
• Calling C-code-libraries in an efficient way, without the hassle of creating a port-driver.
• Executing scripts in VBScript or JavaScript

Compiler-3.0.1

• The compiler builds lists and tuples in a smarter way than previous versions did, meaning that literal lists and tuples of practically any size can now be built. The previous limit was 1024 elements in a literal list or tuple.
• Several changes has been made to the garbage collector and internal memory allocation routines to reduce memory consumption and memory fragmentation. Also, the compiler now makes sure that references to any data that will not be used again will be killed, so that the garbage collector can discard it as soon as possible.
• It is now allowed to use an expression within a pattern, if the expression uses only numeric or bitwise operators, and can be evaluated to a constant at compile-time. E.g., case X of {1+2, T} -> T end.
• The bit syntax, a language addition for constructing and matching binaries. For more infomation, see Extensions to Erlang. Also, the handling of small binaries (up to 64 bytes) has been optimised, as well as splitting of binaries.
• The compiler now supports inlining within a module, see the compiler documentation.
  Numerous known problems and limitations have been corrected, and the optimisation is better. For instance, tuples used in cases for grouping are no longer built.
  The earlier compiler versions v1 (R5) and v2 (R6) have been discontinued because there are no longer any reason to use them.

Inets-2.5.3

•  It is now possible to run more than one HTTP server in an Erlang node listening to the same port but different addresses.

Jinterface-1.2

• A new class, AbstractConnection, has been added to deal with most of the aspects of the Erlang communication protocol, and which can be subclassed in order to provide different levels of support to the application as necessary. OtpConnection is now a subclass to AbstractConnection.
• OtpCookedConnection is a new subclass to AbstractConnection, which together with OtpNode provides an intuitive mailbox-based communication mechanism. By using this interface, applications are no longer required to manage connections explicitly, since the OtpNode now opens and manages connections to remote nodes as needed. Outgoing messages are sent through mailboxes and automatically dispatched through the correct connections to the destination node, while incoming messages are queued in the destination mailbox. This allows parts of an application to communicate with several peers simultaneously without the need to sort and dispatch incoming messages. Additionally, mailboxes can be linked with Erlang processes or with each other, in much the same manner that Erlang processes can be linked together.

Mnesia-3.9.2

• Access to non-local tables avoids disc_only_replicas if possible.
• A new configuration parameter fallback_error_function has been introduced to let the user handle the case when Mnesia has a fallback installed and another Mnesia goes down. The default behavior is as it always been: to kill itself to avoid inconsistencies. The user can now start Erlang with -mnesia fallback_error_function '{UserMod,UserFunc}'.

Orber-3.1.8

• Earlier, Orber did not use the IIOP/GIOP version specified in an external object key when invoking an intra-ORB request.
• The OMG standard now supports an Interoperable Naming Service. Initially, there where two proposals of which Orber earlier supported one of them. Now both standards are supported.
• It is now possible to start Orber as lightweight.
• It is now possible to create pseudo objects, i.e., not server objects.

cosNotification-1.0.2

cosTime-1.0.1

SNMP-3.2.1

• Debugging has been improved. It is now possible to debug all named processes (individually) of the SNMP application. See the documentation for the snmp module for details.
• Filter (audit trail) logs on timestamp.
• The MIB-compiler has been improved. It is now possible to include Description-field into compiled MIB.

Tools-1.6.1

• Xref is a new very capable cross reference tool which works with beam files as input, works fast and eliminates the problem that the old tool Exref had with include files.
  Xref is intended to replace Exref in forthcoming versions of Erlang/OTP.
• Eprof has been optimised to minimise the measuring overhead. Typically, the measured program runs at about 50% of its ordinary speed.