What is KDI?


KDI started as a project at Kosmix. It is meant to provide a common interface between applications with structured external data needs and the various implementations that may fulfill those needs. The interface is meant to act like a simplified database connector.

The KDI project also provides a number of implementations of the interface. These range in sophistication from a single-threaded table stored entirely in memory to a multi-user, distributed table inspired by Google’s BigTable.

The interface was designed with ease of use as a major goal. Clean, safe implementation is also emphasized. Performance is also important, but definitely secondary to the other goals. It is easier to optimize a clean design once the whole system is in view than it is to build a clean system out of independently optimized components.

KDI is a placeholder name. It’s short for Kosmix Data Interface, which is non-so-snazzy.


Does it work?


This is a work in progress. This initial release is v0.0. It probably won’t even compile on your machine. It has been developed in-house at Kosmix on a specific machine configuration. At Kosmix, we’ve used to to store a few TB of data distributed across a cluster of machines, but there are no guarantees that KDI is ready to do that for anyone else. In fact, it’s not even ready for us.

The purpose of this release is to make the project open source to allow collaboration with outside developers.


How do I build it?


KDI has been built on Fedora Core 5 Linux running on x86_64 boxes. We’ve also done a test build on Fedora Core 9 on the same hardware.

For build tools we’ve used:

Tool Versions tried

GCC 4.1.1, 4.3.0 GNU make 3.80, 3.81 Python 2.4.3, 2.5.1

The project uses some external libraries:

Library Versions tried Url

Boost 1.34.1, 1.35.0 http://www.boost.org/ ICE 3.2.1 http://www.zeroc.com/ expat 1.95.8, 2.0.1 zlib 1.2.3

In addition, there are Python bindings for KDI. They have been tested with Python 2.4.3 and Python 2.5.1.

The build script is a somewhat magical collection of Makefiles. To build, go to the root level of the distribution tree (the one containing Makefile) and type “make”. Or if you have multiple cores you can do a parallel build with “make -j N” where N is the number of parallel jobs you’d like. And hey, it may even work. Good luck!

There are other make targets:

make all – build everything, but don’t install (default) make install – build and install (copy) to ./bin and ./lib make syminstall – build and install (symlink) to ./bin and ./lib make unittest – build and run unit tests

There are also build variants:

make VARIANT=release [targets] – turn on optimizer (default) make VARIANT=debug [targets] – make a debug build

Built files go into ./build. Everything in this directory can be generated from source and may be safely deleted.


How do I run it?


You got it to build? Wow!

After you “make install” or “make syminstall”, you’ll have some binaries in your ./bin directory and shared libraries in your ./lib directory. Put the lib directory is in your LD_LIBRARY_PATH (though the binaries do have embedded paths back to their ./build directory locations if you still have that around).

There are 4 programs:

kdiLoad – Load cells into a KDI table kdiScan – Read cells from a KDI table kdiErase – Erase cells from a KDI table kdiNetServer – Host a networked KDI table

KDI tables are referred to by URI. The URI scheme is used to select the KDI implementation. There are a few provided KDI schemes:

mem: – in-memory read/write table local: – read/write table on local disk kdi: – read/write table hosted on a networked server

In addition, there are a couple of prefix schemes:

sync – allow multiple threads to use the same table in a synchronized way meta – use a meta table to present a larger logical table

At some point I’ll need to put together some usage examples and documentation. In the mean time, RTFS! :)


Known issues


2008-07-09: The warp/plugin unit test fails when using Boost 1.35. This is a bug in Boost: http://svn.boost.org/trac/boost/ticket/1723 Also see: http://groups.google.com/group/boost-list/browse_thread/thread/4bb3cc616d41ce01/c6ed8bdc48e081cc?lnk=raot