Aus der Amazon.de-Redaktion
Der erste Band der Reihe Unix Network Programming, Networking APIs: Sockets and XTI von W. Richard Stevens deckt so ziemlich alles rund um das Thema Kommunikation eigener Anwendungen mit anderen Computern innerhalb eines Netzwerkes ab. Im vorliegenden zweiten Band hingegen erörtert Stevens ausführlich die Kommunikation zwischen verschiedenen Anwendungen auf dem eigenen Computer. Darin besteht ein großer Unterschied, und Stevens versteht es, das zu verdeutlichen.
Stevens macht den Leser zunächst mit den internen Strukturen von Posix Interprocess Communication (IPC) und SystemV (SysV) IPC bekannt; danach erklärt er FIFOs, Message Queues, wie man den Zugriff auf Dateien sperrt und wieder freigibt, Semaphoren, Shared- Memory, und RPCs (Remote Procedure Calls). Er verweist zudem auf die Unterschiede zwischen der Implementierung von Semaphoren, Message Queues und Shared Memory bei Posix IPC und SysV IPC. Zusätzlich enthält das Buch viele Anmerkungen und Beispiele zum besseren Verständnis.
Das Buch ist besonders bei der praktischen Arbeit mit Posix IPC und SysV IPC hilfreich und ist daher gerade für Programmierer von besonderem Wert. Darüberhinaus hilft es dem Leser bei der Entscheidung, welche Version er am besten für seine Zwecke einsetzt indem die Unterschiede zwischen Posix IPC und SysV IPC bestens erklärt werden. --Doug Beaver
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Stevens introduces the reader to the internal structures of Posix interprocess communication (IPC) and System V (SysV) IPC; pipes and first in, first outs (FIFOs); message queues; how to lock and unlock files and records; semaphores; shared memory; and remote procedure calls (RPCs). He explains the difference between the Posix and SysV implementations of semaphores, message queues, and shared memory. There are also plenty of notes and examples for the reader.
This book is invaluable for programmers because it explains all of those little "gotchas" that always seem to pop up. In addition, the explanations of the differences between Posix IPC and SysV IPC really help readers decide which version they'd like to use for their applications. --Doug Beaver
Kurzbeschreibung
Synopsis
Buchrückseite
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Don't miss the rest of the series!
- Vol. 1, Networking APIs: Sockets and XTI
- Vol. 3, Applications (forthcoming)
The only guide to UNIX(r) interprocess communications you'll ever need!
Well-implemented interprocess communications (IPC) are key to the performance of virtually every non-trivial UNIX program. In UNIX Network Programming, Volume 2, Second Edition, legendary UNIX expert W. Richard Stevens presents a comprehensive guide to every form of IPC, including message passing, synchronization, shared memory, and Remote Procedure Calls (RPC).
Stevens begins with a basic introduction to IPC and the problems it is intended to solve. Step-by-step you'll learn how to maximize both System V IPC and the new Posix standards, which offer dramatic improvements in convenience and performance. You'll find extensive coverage of Pthreads, with many examples reflecting multiple threads instead of multiple processes. Along the way, you'll master every current IPC technique and technology, including:
- Pipes and FIFOs.
- Posix and System V Message Queues
- Mutexes and Condition Variables
- Read-Write Locks
- Record Locking
- Posix and System V Semaphores
- Posix and System V Shared Memory
- Solaris Doors and Sun RPC
- Performance Measurements of IPC Techniques
If you've read Stevens' best-selling first edition of UNIX Network Programming, this book expands its IPC coverage by a factor of five! You won't just learn about IPC "from the outside." You'll actually create implementations of Posix message queues, read-write locks, and semaphores, gaining an in-depth understanding of these capabilities you simply can't get anywhere else.
The book contains extensive new source code-all carefully optimized and available on the Web. You'll even find a complete guide to measuring IPC performance with message passing bandwidth and latency programs, and thread and process synchronization programs.
The better you understand IPC, the better your UNIX software will run. One book contains all you need to know: UNIX Network Programming, Volume 2, Second Edition.
Über den Autor
W. RICHARD STEVENS is author of UNIX Network Programming, First Edition, widely recognized as the classic text in UNIX networking. He is also author of Advanced Programming in the UNIX Environment and the TCP/IP Illustrated Series. Stevens is an acknowledged UNIX and networking expert, sought-after Instructor, and occasional consultant.
Prolog. Abdruck erfolgt mit freundlicher Genehmigung der Rechteinhaber. Alle Rechte vorbehalten.
Introduction
Most nontrivial programs involve some form of IPC or Interprocess Communication. This is a natural effect of the design principle that the better approach is to design an application as a group of small pieces that communicate with each other, instead of designing one huge monolithic program. Historically, applications have been built in the following ways:
1. One huge monolithic program that does everything. The various pieces of the program can be implemented as functions that exchange information as function parameters, function return values, and global variables.
2. Multiple programs that communicate with each other using some form of IPC. Many of the standard Unix tools were designed in this fashion, using shell pipelines (a form of IPC) to pass information from one program to the next.
3. One program comprised of multiple threads that communicate with each other using some type of IPC. The term IPC describes this communication even though it is between threads and not between processes. Combinations of the second two forms of design are also possible: multiple processes, each consisting of one or more threads, involving communication between the threads within a given process and between the different processes.
What I have described is distributing the work involved in performing a given application between multiple processes and perhaps among the threads within a process. On a system containing multiple processors (CPUs), multiple processes might be able to run at the same time (on different CPUs), or the multiple threads of a given process might be able to run at the same time. Therefore, distributing an application among multiple processes or threads might reduce the amount of time required for an application to perform a given task.
This book describes four different forms of IPC in detail:
1. message passing (pipes, FIFOs, and message queues),
2. synchronization (mutexes, condition variables, read-write locks, file and record locks, and semaphores),
3. shared memory (anonymous and named), and
4. remote procedure calls (Solaris doors and Sun RPC).
This book does not cover the writing of programs that communicate across a computer network. This form of communication normally involves what is called the sockets API (application program interface) using the TCP/IP protocol suite; these topics are covered in detail in Volume 1 of this series Stevens 1998.
One could argue that single-host or nonnetworked IPC (the subject of this volume) should not be used and instead all applications should be written as distributed applications that run on various hosts across a network. Practically, however, single-host IPC is often much faster and sometimes simpler than communicating across a network. Techniques such as shared memory and synchronization are normally available only on a single host, and may not be used across a network. Experience and history have shown a need for both nonnetworked IPC (this volume) and IPC across a network (Volume 1 of this series).
This current volume builds on the foundation of Volume 1 and my other four books, which are abbreviated throughout this text as follows:
- UNPv1: UNIX Network Programming, Volume 1 Stevens 1998,
- APUE: Advanced Programming in the UNIX Environment Stevens 1992,
- TCPv1: TCP/IP Illustrated, Volume 1 Stevens 1994,
- TCPv2: TCP/IP Illustrated, Volume 2 Wright and Stevens 1995, and
- TCPv3: TCP/IP Illustrated, Volume 3 Stevens 1996.
Although covering IPC in a text with "network programming" in the title might seem odd, IPC is often used in networked applications. As stated in the Preface of the 1990 edition of UNIX Network Programming, "A requisite for understanding how to develop software for a network is an understanding of interprocess communication (IPC)."
Changes from the First Edition
This volume is a complete rewrite and expansion of Chapters 3 and 18 from the 1990 edition of UNIX Network Programming. Based on a word count, the material has expanded by a factor of five. The following are the major changes with this new edition:
- In addition to the three forms of "System V IPC" (message queues, semaphores, and shared memory), the newer Posix functions that implement these three types of IPC are also covered. (I say more about the Posix family of standards in Section 1.7.) In the coming years, I expect a movement to the Posix IPC functions, which have several advantages over their System V counterparts.
- The Posix functions for synchronization are covered: mutex locks, condition variables, and read-write locks. These can be used to synchronize either threads or processes and are often used when accessing shared memory.
- This volume assumes a Posix threads environment (called "Pthreads"), and many of the examples are built using multiple threads instead of multiple processes.
- The coverage of pipes, FIFOs, and record locking focuses on their Posix definitions.
- In addition to describing the IPC facilities and showing how to use them, I also develop implementations of Posix message queues, read-write locks, and Posix semaphores (all of which can be implemented as user libraries). These implementations can tie together many different features (e.g., one implementation of Posix semaphores uses mutexes, condition variables, and memory-mapped I/O) and highlight conditions that must often be handled in our applications (such as race conditions, error handling, memory leaks, and variable-length argument lists). Understanding an implementation of a certain feature often leads to a greater knowledge of how to use that feature.
- The RPC coverage focuses on the Sun RPC package. I precede this with a description of the new Solaris doors API, which is similar to RPC but on a single host. This provides an introduction to many of the features that we need to worry about when calling procedures in another process, without having to worry about any networking details.
Readers
This text can be used either as a tutorial on IPC, or as a reference for experienced programmers. The book is divided into four main parts:
- message passing,
- synchronization,
- shared memory, and
- remote procedure calls
but many readers will probably be interested in specific subsets. Most chapters can be read independently of others, although Chapter 2 summarizes many features common to all the Posix IPC functions, Chapter 3 summarizes many features common to all the System V IPC functions, and Chapter 12 is an introduction to both Posix and System V shared memory. All readers should read Chapter 1, especially Section 1.6, which describes some wrapper functions used throughout the text. The Posix IPC chapters are independent of the System V IPC chapters, and the chapters on pipes, FIFOs, and record locking belong to neither camp. The two chapters on RPC are also independent of the other IPC techniques.
To aid in the use as a reference, a thorough index is provided, along with summaries on the end papers of where to find detailed descriptions of all the functions and structures. To help those reading topics in a random order, numerous references to related topics are provided throughout the text.
Source Code and Errata Availability
The source code for all the examples that appear in this book is available from the author's home page (listed at the end of this Preface). The best way to learn the IPC techniques described in this book is to take these programs, modify them, and enhance them. Actually writing code of this form is the only way to reinforce the concepts and techniques. Numerous exercises are also provided at the end of each chapter,...
