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00001 //# IO.h: Basic classes and global functions for IO and object persistency 00002 //# Copyright (C) 1995,1996,1999,2001 00003 //# Associated Universities, Inc. Washington DC, USA. 00004 //# 00005 //# This library is free software; you can redistribute it and/or modify it 00006 //# under the terms of the GNU Library General Public License as published by 00007 //# the Free Software Foundation; either version 2 of the License, or (at your 00008 //# option) any later version. 00009 //# 00010 //# This library is distributed in the hope that it will be useful, but WITHOUT 00011 //# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 00012 //# FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public 00013 //# License for more details. 00014 //# 00015 //# You should have received a copy of the GNU Library General Public License 00016 //# along with this library; if not, write to the Free Software Foundation, 00017 //# Inc., 675 Massachusetts Ave, Cambridge, MA 02139, USA. 00018 //# 00019 //# Correspondence concerning AIPS++ should be addressed as follows: 00020 //# Internet email: aips2-request@nrao.edu. 00021 //# Postal address: AIPS++ Project Office 00022 //# National Radio Astronomy Observatory 00023 //# 520 Edgemont Road 00024 //# Charlottesville, VA 22903-2475 USA 00025 //# 00026 //# $Id: IO.h 20615 2009-06-09 02:16:01Z Malte.Marquarding $ 00027 00028 #ifndef CASA_IO_H 00029 #define CASA_IO_H 00030 00031 //# Includes for object persistency. 00032 #include <casa/IO/AipsIO.h> 00033 #include <casa/IO/AipsIOCarray.h> 00034 00035 //# Includes for general IO. 00036 #include <casa/IO/ByteSinkSource.h> 00037 00038 //# Includes for underlying IO classes. 00039 #include <casa/IO/CanonicalIO.h> 00040 #include <casa/IO/RawIO.h> 00041 #include <casa/IO/RegularFileIO.h> 00042 #include <casa/IO/FilebufIO.h> 00043 #include <casa/IO/FiledesIO.h> 00044 #include <casa/IO/MemoryIO.h> 00045 00046 00047 namespace casa { //# NAMESPACE CASA - BEGIN 00048 00049 // <module> 00050 00051 // <summary> 00052 // Basic classes and global functions for IO and object persistency 00053 // </summary> 00054 00055 // <reviewed reviewer="UNKNOWN" date="before2004/08/25" demos=""> 00056 // </reviewed> 00057 00058 // <synopsis> 00059 // This module provides the basic IO functionality for the AIPS++ classes. 00060 // There are two IO mechanisms: 00061 // <ol> 00062 // <li> Class <linkto class=AipsIO:description>AipsIO</linkto> 00063 // provides the object persistency mechanism. 00064 // The templated global functions in 00065 // <linkto file="AipsIOCarray.h#AipsIOCarray">AipsIOCarray.h</linkto> 00066 // form a little layer upon AipsIO. They provide the means to put or 00067 // get a C-style array of any type. 00068 // <li> Class <linkto class=ByteSinkSource:description>ByteSinkSource</linkto> 00069 // and its ancestors provide a general IO mechanism. 00070 // </ol> 00071 // 00072 // Both use the underlying IO framework which define where and how 00073 // the data is written. The how-part is defined by classes derived from 00074 // <linkto class=TypeIO:description>TypeIO</linkto> as shown 00075 // in the <a href=IO/IO_1.html>OMT diagram</a>. 00076 // There are three such classes: 00077 // <ol> 00078 // <li> <linkto class=CanonicalIO:description>CanonicalIO</linkto> reads/writes 00079 // data in canonical (machine-independent) format. This should be 00080 // used when data are meant to be exportable. 00081 // It uses the conversion functions in class 00082 // <linkto class=CanonicalConversion:description>CanonicalConversion 00083 // </linkto>. 00084 // <li> <linkto class=RawIO:description>RawIO</linkto> reads/writes 00085 // data in native (machine-dependent) format. This can be used when 00086 // data are not exported. 00087 // <li> <linkto class=ConversionIO:description>ConversionIO</linkto> 00088 // reads/writes in an external format as defined at construction time. 00089 // This can be used when the external format can be one of several 00090 // (e.g. VAX or IBM for a WSRT archive tape). In this way the 00091 // format has to be defined only once and thereafter is it handled 00092 // correctly by the polymorphism mechanism. 00093 // </ol> 00094 // The where-part is defined by classes derived from 00095 // <linkto class=ByteIO:description>ByteIO</linkto> as shown 00096 // in the <a href=IO/IO_2.html>OMT diagram</a>. 00097 // There are a few such classes: 00098 // <ol> 00099 // <li> <linkto class=RegularFileIO:description>RegularFileIO</linkto> uses a 00100 // regular file to hold the data. Internally it uses FilebufIO (see below). 00101 // <li> <linkto class=LargeRegularFileIO:description>LargeRegularFileIO</linkto> 00102 // is similar to RegularFileIO for 64-bit systems. 00103 // <li> <linkto class=FilebufIO:description>FilebufIO</linkto> does the IO 00104 // in a buffered way similar to the <src>stdio</src> system. However, it 00105 // does not use stdio because that gave problems when doing concurrent 00106 // access from multiple processes. 00107 // <li> <linkto class=LargeFilebufIO:description>LargeFilebufIO</linkto> is 00108 // similar to FilebufIO for 64-bit systems. 00109 // <li> <linkto class=FiledesIO:description>FiledesIO</linkto> uses the 00110 // UNIX IO-functions like <src>open, read</src> to do IO directly. 00111 // It does not use an internal buffer. Instead it always does 00112 // physical IO. It is meant for IO operations where large chunks of 00113 // a file are accessed and for IO on sockets, pipes, etc.. 00114 // <li> <linkto class=LargeFiledesIO:description>LargeFiledesIO</linkto> is 00115 // similar to FiledesIO for 64-bit systems. 00116 // <li> <linkto class=MemoryIO:description>MemoryIO</linkto> uses a 00117 // (possibly expandable) buffer in memory to hold the data. 00118 // <li> <linkto class=MMapIO>MMapIO:description</linkto> uses memory-mapped IO. 00119 // Be careful to use this on 32-bit machines, because its address space is 00120 // too small to handle a file of a few GBytes. 00121 // </ol> 00122 // 00123 // The IO framework is easily expandable. One can for instance think of a 00124 // class <src>AsciiIO</src> derived from <src>TypeIO</src> 00125 // to hold data in ASCII format. 00126 // <br> A class <src>TapeIO</src> could be derived from <src>ByteIO</src> 00127 // to access tape files. This class can also contain functions to skip to 00128 // a tape file, which the user can call directly. 00129 // Similarly a class <src>RemoteTapeIO</src> could be developed. 00130 // </synopsis> 00131 00132 // </module> 00133 00134 00135 00136 } //# NAMESPACE CASA - END 00137 00138 #endif 00139