244 lines
11 KiB
Plaintext
244 lines
11 KiB
Plaintext
With the author's permission, SimGear now bundles MetaKit. MetaKit is
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explained
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The MetaKit Library 2.01 March 2000
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==============================================================================
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WHAT IT IS - MetaKit is an embeddable database which runs on Unix, Windows,
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Macintosh, and other platforms. It lets you build applications which
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store their data efficiently, in a portable way, and which will not need a
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complex runtime installation. In terms of the data model, MetaKit takes
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the middle ground between RDBMS, OODBMS, and flat-file databases - yet it
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is quite different from each of them.
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WHAT IT ISN'T - MetaKit is not: 1) multi-user/-threading, 2) scalable to
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gigabytes, 3) proprietary software, 4) full of bugs, 5) just a toy.
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TECHNOLOGY - Everything is stored variable-sized yet with efficient positional
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row access. Changing an existing datafile structure is as simple as re-
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opening it with that new structure. All changes are transacted. You can
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mix and match software written in C++, Python, and Tcl. Things can't get
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much more flexible...
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CORE - The Metakit core library is written in C++. It has a code footprint of
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just over 100 Kb on Windows. It can be used as DLL, or linked statically.
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Debug builds include extensive assertion checks to catch problems early.
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PYTHON - The binding for Python is called "Mk4py". It uses SCXX by Gordon
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McMillan as C++ glue interface. The source is in directory "python/".
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TCL/TK - The MK extension for Tcl is called "Mk4tcl". It is being used in a
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number of commercial projects, for in-house use as well as in commercially
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distributed products. The source is in directory "tcl/".
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LICENSE AND SUPPORT - MetaKit 2.01 is distributed as open source software (the
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X/MIT-style license is at the end of this document). Commercial support
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is available through an Enterprise License, see the URL mentioned below.
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DOCUMENTATION - All documentation uses HTML. The main page is "MetaKit.html",
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which leads to the rest of the documentation in the "doc/" directory.
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WEBSITE URLS - The main pages on the world wide web, for news and downloads:
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Homepage: http://www.equi4.com/metakit/
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Python news: http://www.equi4.com/metakit/python.html
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Tcl/Tk news: http://www.equi4.com/metakit/tcl.html
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License info: http://www.equi4.com/metakit/license.html
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Contact info: http://www.equi4.com/contact.html
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INSTALLATION
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============
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Starting with this release, all platform builds and language bindings are now
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designed to work from a single common "builds/" directory. It turns out to
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be impossible to keep build side-effects limited to *just* this directory
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(CodeWarrior can't be told where to place its temp data, and Visual C++ still
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alters a few files next to the project ".dsw" file, to name two offenders).
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UNIX
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It is no longer advised to build the Unix code in the "unix/" directory.
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Instead, you should perform the following steps:
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% cd builds
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% ../unix/configure
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% make
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% make test
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And optionally (this only installs the core lib, not script extensions):
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% make install
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By switching to the "builds/" directory, you will keep the distribution
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directory tree 100% unaltered. All changes are made in this subdir, and
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all final build results are left behind in this same subdir.
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Nastiness: if you build Mk4tcl, please do a "make Mk4tcl.so" as well.
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And if you intend to create the Python extension, do a "make Mk4py.so".
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The "libmk4tcl.so.0.0.0" and "libMk4py.so.0.0.0" targets are bogus ones.
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You will probably have to make changes in the makefile to locate the
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proper includes and libs for Python (Tcl has been fixed, see "--with-tcl).
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You probably only need to adjust "CXX_SWITCHES_PY" to find the headers.
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To build with STL containers and strings, you can do the following:
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make CXXFLAGS='-Dq4_STD' test # add -O3 etc, as needed
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This passes the test suite on Linux RedHat 5.2 with gcc 2.95-2.
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See below for some platform-specific build notes.
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WINDOWS
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There is a "win/" directory which contains subdirectories for a number of
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compiler systems. MetaKit has been built with many different compilers
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in the past (Microsoft, Borland, Watcom, Symantec, Metrowerks, Optima),
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but to preserve my sanity (there are 12 configurations for MSVC6 alone!),
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I am limiting myself to MSVC6, MWCW5, Borland C++ Builder 4, and Cygwin.
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The MS Visual C++ 6.0 project is "win/msvc60/mksrc.dsw", with subprojects
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for the C++ demo (mkdemo), building dll's (mkdll), static libs (mklib),
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regression tests (mktest), as well as Tcl (mktcl) and Python (mkpython).
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It has been set up to place all intermediate files and final results in
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the "builds/" subdirectory, even though you'll launch it from "win/".
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To build with STL containers and strings under MSVC, define "q4_STD".
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To build with MFC containers and strings under MSVC, define "q4_MFC".
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The Metrowerks Codewarrior project is in the "mac/" directory, and can be
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used to build both Mac and Windows versions (on either Mac *or* Windows).
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The core libraries are built with "mac/cw5.mcp", demos / tests are built
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with "cw5apps.mcp", Tcl is "cw5tcl.mcp", and Python is "cw5python.mcp".
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The Borland C++ Builder projects have not yet been incorporated in this
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release, but the "KitViewer" application is an example of how to use BCB.
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The Cygwin build (B20.1 / gcc 2.95.2) is different, because it uses the
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unix autoconf system, and must be launched as described above for UNIX.
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I have upgraded to the latest development of libtool to be able to build
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DLL's with Cygwin. You can build the "-mno-cygwin" version by editing
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the Makefile by hand and adding that option to CXXFLAGS.
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Rob Bloodgood adds that the following GCC options are for maximum code
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efficiency on x86 hardware: "-O2 -m486 -malign-loops=2 -malign-jumps=2".
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I have not yet tried this myself, but am passing on the tip.
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MACINTOSH
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The Mac version requires Metrowerks CodeWarrior 5. See the info above
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in the Windows section (MWCW is multi-platform). The projects are all
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located in the "mac/" folder, which is also where MWCW will place its own
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"... Data" folders with intermediate results. As with all other setups,
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final results are made to end up in the "builds/" directory.
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Static 68K builds appear to work fine, the 68K CFM variants will need
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some more work (I couldn't get the libraries to export their symbols).
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PLATFORM-SPECIFIC NOTES
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=======================
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* Linux RH 5.2 / gcc 2.95.2
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Builds with gcc 2.95.2 work out of the box. The Tcl extension ends up as
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".libs/libmk4tcl.so.0.0.0" (to please libtool), and should be renamed to
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"Mk4tcl.so". Similarly, ".libs/libMk4py.so.0.0.0" is in fact the Python
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extension, and *must* be renamed to "Mk4py.so" to call it from Python.
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The core MK libs end up as ".libs/libmk4.a" and ".libs/libmk4.so.0.0.0".
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* Solaris 2.6 / gcc 2.8.1
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The Solaris builds are nasty for several reasons:
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- I do not own such a machine, and often have to make arrangements
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(or fight limited space on one of the machines I can telnet to).
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- The gcc 2.8.1 optimizer appears to be buggy, I have had to turn off
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the default "-O3" flag to prevent compiler crashes (several files).
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This problems appears to be resolved with gcc 2.95.
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- Locking on Solaris (especially w.r.t NFS) remains a mystery to me.
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The Tcl and Python extensions both use locking (the core not yet).
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See tcl/Mk4tcl.cpp around line 520, and python/PyStorage.cpp around
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line 80 for details. It's all pretty messy, and not 100% correct.
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Despite this, I'm doing my best to resolve these issues. Having a solid
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build of the core *and* of Tcl / Python extensions is quite important.
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* Other Unix systems
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No further notes, though many systems will build fine out of the box.
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* Windows
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MSVC 6 builds MK as static lib and as DLL (universal config, I have not
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yet created build versions with MFC or STL, mainly because MK can now be
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used in all contexts regardless of how it was built). The Python and Tcl
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extensions build as dynamic extensions (a static build is easy to add).
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MWCW 5 builds MK as static lib and as DLL (interestingly enough, the DLL
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is slightly smaller than MSVC 6 - 102 vs 108 Kb - when their runtimes are
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linked in dynamically as well). I have not added Win builds for Tcl or
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Python, since MSVC 6 has those already.
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Cygwin B20.1, with gcc 2.95.2 ugrade, also builds MK as static lib and as
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DLL. Both "pure" Cygwin (i.e. requiring cygwin1.dll) and mingw32 (using
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the -mno-cygwin flag) build, but there are some hairy include issues when
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it comes to choosing the right locking model for Tcl and Python. These
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issues have not been resolved fully.
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* Macintosh
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MWCW 5 builds PPC shared libs, PPC static libs, and 68K static libraries.
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Building 68K CFM libraries leads to a "MetaKit 68K.shlb" which comes out
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of the linker without errors, but the result does not seem to have any
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export symbols defined (despite the fact that the library is over 200 K).
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Because of that, I've been unable to build apps or Mk4tcl/Mk4py so far.
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The other three configurations build, but for some reason MK's regression
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test stops at L03 (everything up to that point looks ok, i.e. over 90%).
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The Mk4tcl PPC extension appears to work (quick manual test), and so does
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the Python extension, "Mk4py.PPC.slb". I have not yet given these two
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a serious workout, hoping to have a basic test harness in place soon.
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* VMS, BeOS, ...
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No news yet, please report your findings with any other platform builds.
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WHAT'S MISSING HERE
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===================
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- a section on basic concepts (or maybe it doesn't belong here?)
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- a section on getting started (C++, Python, Tcl all differ - point to
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the respective intro pages)
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- maybe a small sample for each of C++ / Tcl / Python, to give an idea
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- mention TclKit, scripted docs (WiKit/Tequila?), VFS?
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- I forgot... please tell me :)
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LICENSE AND COPYRIGHT STATEMENT
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===============================
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Copyright (c) 1996-2000 Jean-Claude Wippler
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Permission is hereby granted, free of charge, to any person obtaining a
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copy of this software and associated documentation files (the "Software"),
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to deal in the Software without restriction, including without limitation
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the rights to use, copy, modify, merge, publish, distribute, sublicense,
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and/or sell copies of the Software, and to permit persons to whom the
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Software is furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included
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in all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
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OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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DEALINGS IN THE SOFTWARE.
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==============================================================================
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-- Jean-Claude Wippler <jcw@equi4.com>
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