How to Build LSB Applications

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Packaging

As I mentioned earlier, the LSB specifies that a package must be delivered in the RPM file format. This does not mean that RPM has to be used to build or package your application, although it may be the most practical option, depending on whether you already are using it. Other options would be creating the package in the Debian format, and then using alien to convert it to RPM. Or, you could use some other tool for creating the RPM file format. We have the beginnings of a tool called mkpkg to create the RPM format file, but it likely will require something to sit on top of it to make it useful to any but the most die-hard hacker.

In our application battery, we currently build the application and install it in a temporary root and then invoke RPM to package up the install application. This may seem a little clunky, but it works without much pain and produces more consistent results across all of the different versions of RPM found in the wild.

Here is a sample spec file for the xpaint application:

Summary: An X Window System paint program
Summary: XPaint
Name: lsb-xpaint
Version: 2.6.2
Release: 3
Vendor: Free Standards Group
License: MIT
Group: Appbat/graphics
Buildroot: /usr/src/appbat/pkgroot/lsb-xpaint
AutoReqProv: no
PreReq: lsb >= 1.3

%description
LSB conforming version of xpaint. XPaint is an
X Window System color image editing program and
painting program. Xpaint is added to the LSB
Application Battery primarily to demonstrate the
use of X11 libraries.

%pre

%install

%post

%preun

%postun

%clean

%files

%attr ( - bin bin ) /opt/lsb-xpaint

Full source code for building and packaging this and the other applications in the application battery can be found in the LSB Project CVS tree.

Does This Really Work?

Yes, it really does work, although to be fair, we still are running into corner cases and various applications that don't always follow the rules for clean, portable code. As part of the verification for the LSB, we have created an application battery built from the tools described here. This set of applications includes Apache, Samba, Lynx, Python, xpdf and groff. We have tried to select a set of real applications that provide coverage over as much of the LSB set of interfaces as possible.

What about C++ Applications?

LSB version 1.3 does not support C++, so the rule requiring the library to be linked statically applies. We are adding support for C++ to LSB 2.0 to avoid this. We provide the lsbdev-c++ package, which contains a version of libstdc++ that was configured and built with lsbcc. This and GCC version 3.2 seem to produce good results. We have tried other combinations of compilers and different versions of the C and C++ libraries but ran into various problems, depending on the nature of the application.

Future Directions

For the LSB in general, we will continue to add additional libraries to the specification as long as there is consensus that they are needed and have reached a certain level of stability. This should help close the gap between how distribution-provided and LSB-conforming applications are built.

For the LSB development environment, we will continue to make the tools better and more transparent. The development environment is being maintained actively, and feedback from people using these tools is appreciated. With the addition of C++ in LSB 2.0, the development environment will be able to drop the lsbdev-c++ package being used today in favor of the C++ stub library, which will move into the base LSB development package.

Currently, you may have to set several options in an rpmrc or rpmmacros file to make RPM produce LSB-conforming packages. It is our hope that we can come up with an LSB mode for rpmbuild that can handle all of this automatically. Hopefully, it will make it even easier to build existing packages that conform to the LSB.

Acknowledgements

First off, thanks to the Free Standards Group and its members for providing the support to the LSB Project that has enabled us to accomplish as much as we have. Secondly, thanks to the core group of developers working on the development environment for the LSB, including Chris Yeoh, Marvin Heffler and especially Mats Wichmann for their patience and persistence during the more experimental phases of this project.

Resources for this article: /article/7459.

Stuart R. Anderson (anderson@freestandards.org) made the mistake of being overheard while saying “I know how to fix that”, and he has been the lead developer of the LSB Written Specification ever since. When not working on the LSB, Stuart keeps busy enlightening South Carolina to open-source ideas by converting companies one at a time.

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