$Id: README 96983 2013-04-11 11:14:11Z schmidt $

This document is also available at the following URL:

http://www.dre.vanderbilt.edu/~schmidt/ACE.html

All software and documentation is available via both anonymous ftp and the http.]

THE ADAPTIVE COMMUNICATION ENVIRONMENT (ACE)

An Object-Oriented Network Programming Toolkit

Overview of ACE

The ADAPTIVE Communication Environment (ACE) is an object-oriented (OO) toolkit that implements fundamental design patterns for communication software. ACE provides a rich set of reusable C++ wrappers and frameworks that perform common communication software tasks across a range of OS platforms, including Win32/Win64, most versions of UNIX (e.g., SunOS, HP-UX , AIX, Linux, NetBSD, and FreeBSD), real-time operating systems (e.g., VxWorks, Chorus, LynxOS, and QNX), OpenVMS, and MVS OpenEdition. A single source tree is used for all these platforms and porting ACE to other platforms is relatively easy.

The communication software components provided by ACE include event demultiplexing and event handler dispatching, service initialization, interprocess communication, shared memory management, message routing, dynamic (re)configuration of distributed services, multi-threading, and concurrency control. There are both C++ and Java versions of ACE available.

ACE is targeted for developers of high-performance and real-time communication services and applications on UNIX, POSIX, and Win32 platforms. ACE simplifies the development of OO network applications and services that utilize interprocess communication, event demultiplexing, explicit dynamic linking, and concurrency. ACE automates system configuration and reconfiguration by dynamically linking services into applications at run-time and executing these services in one or more processes or threads.

ACE is currently used in commercial projects and products by dozens of companies including Ericsson, Bellcore, Siemens, Motorola, Kodak, Boeing, Lucent, DEC, Lockheed Martin, and SAIC. Commercial support for ACE is available from several companies as listed at http://www.cs.wustl.edu/~schmidt/commercial-support.html

C++ Wrappers for OS Interfaces

The lower-level portions of ACE provide a set of portable and type-secure C++ wrappers that encapsulate the following C language OS interfaces:

    . IPC mechanisms
            -- e.g., Internet- and UNIX-domain sockets, TLI, Named
               Pipes (for UNIX and Win32) and STREAM pipes;

    . Event demultiplexing
            -- e.g., select(), poll(), and Win32
               WaitForMultipleObjects and I/O completion ports;

    . Multi-threading and synchronization
            -- e.g., Solaris threads, POSIX Pthreads, and Win32
               threads;

    . Explicit dynamic linking
            -- e.g., dlopen/dlsym on UNIX and LoadLibrary/GetProc
               on Win32;

    . Memory-mapped files and shared memory management
            -- e.g., BSD mmap(), SYSV shared memory, and Win32
               shared memory;

    . System V IPC
            -- e.g., shared memory, semaphores, message queues.

The OS Adaptation Layer shields the upper levels of ACE from platform dependencies associated with the underlying OS interfaces.

Frameworks and Class Categories

ACE also contains a higher-level network programming framework that integrates and enhances the lower-level C++ wrappers. This framework supports the dynamic configuration of concurrent distributed services into applications. The framework portion of ACE contains the following class categories:

    . The Reactor
            -- Supports both Reactive and Proactive I/O;

    . The Service Configurator
            -- Support dynamic (re)configuration of objects;

    . The ADAPTIVE Service Executive
            -- A user-level implementation of System V STREAMS,
               that supports modular integration of
               hierarchically-related communicaion services;

    . Concurrency
            -- Various types of higher-level concurrency
               control and synchronization patterns (such as
               Polymorphic Futures and Active Objects);

    . Shared Malloc
            -- Components for managing dynamically allocation
               of shared and local memory;

Distributed Services and Components

Finally, ACE provides a standard library of distributed services that are packaged as components. These service components play two roles in ACE:

    1. They provide reusable components for common distributed
       system tasks such as logging, naming, locking, and time
       synchronization.

    2. They illustrate how to utilize ACE features such as the
       Reactor, Service Configurator, Service Initialization,
       Concurrency, and IPC components.

Middleware Applications

ACE has been used in research and development projects at many universities and companies. For instance, it has been used to build avionics systems at Boeing, telecommunication systems at Bellcore, Ericsson, Motorola, and Lucent; medical imaging systems at Siemens and Kodak; and many academic research projects. Two example middleware applications provided with the ACE release include:

    1. The ACE ORB (TAO) -- TAO is a real-time implementation of
       CORBA built using the framework components and patterns
       provided by ACE.

    2. JAWS -- JAWS is a high-performance, adaptive Web server
       built using the components in ACE.

OBTAINING ACE

ACE may be obtained electronically from http://download.dre.vanderbilt.edu. This release contains the source code, test drivers, and example applications (including JAWS) for C++ wrapper libraries and the higher-level ACE network programming framework developed as part of the ADAPTIVE project at the University of California, Irvine, Washington University, St. Louis, and Vanderbilt University.

You can get The ACE ORB (TAO) in a companion release at the same URL.

ACE DOCUMENTATION AND TUTORIALS

Many of the C++ wrappers and higher-level components have been described in issues of the C++ Report, as well as in proceedings of many journals, conferences, and workshops.

A collection of white papers and tutorial handouts are included at

http://www.dre.vanderbilt.edu/~schmidt/ACE-papers.html

This page contains PDF versions of various papers that describe different aspects of ACE.

This material is also available available via the WWW at URL:

http://www.dre.vanderbilt.edu/~schmidt/ACE.html

ACE MAILING LIST AND NEWSGROUP

A mailing list, ace-users@list.isis.vanderbilt.edu, is available for discussing bug fixes, enhancements, and porting issues regarding ACE. Please send mail to me at the ace-users-request@list.isis.vanderbilt.edu if you'd like to join the mailing list. There is also a USENET newsgroup called comp.soft-sys.ace. Please see http://www.dre.vanderbilt.edu/~schmidt/ACE-mail.html for details on how to subscribe to the mailing list.

BUILDING AND INSTALLING ACE

Please refer to the http://www.dre.vanderbilt.edu/~schmidt/ACE-install.html file for information on how to build and test the ACE wrappers. The BIBLIOGRAPHY file contains information on where to obtain articles that describe the ACE wrappers and the ADAPTIVE system in more detail.

The current release has been tested extensively, but if you find any bugs, please report them to the ACE mailing list ace-users@list.isis.vanderbilt.edu using the $ACE_ROOT/PROBLEM-REPORT-FORM. Please use the same form to submit questions, comments, etc. To ensure that you see responses, please do one of the following:

1) Subscribe to the ace-users mail list, by sending email with
   contents "subscribe ace-users" to
   ace-users-request@list.isis.vanderbilt.edu.

2) Or, monitor the comp.soft-sys.ace newsgroup for responses.

ACKNOWLEDGEMENTS

Please see the file `$ACE_ROOT/THANKS' for a list of the thousands of people who've contributed to ACE and TAO over the years.