During this time I’ve been working on XesamQLib creation. This is a Qt based library for accessing Xesam services.
Its API is going to be similar to Xesam-glib one and it will make life easier for developers who want to interact with programs exposing Xesam service (who talked about Strigi? )

Right now I’m finishing to clean the code, in order to publish a first version of XesamQLib on KDE repository.
I’ll keep you updated.

KDE integration: Flavio will coordinate the definition of interfaces over which KDE will handle searching and metadata. He can ask Aaron, Evgeny and Jos for help with the interface design. The interface will cover:

• Querying via Xesam
• Configuration of the Strigi daemon
• Indexing and deindexing of data by passing it to the daemon (allowing for indexing for more than just files)
• Controlling the daemon (starting, stopping, pausing)

Once this interface will be ready, it will be easy to integrate Strigi functionalities inside KDE programs. This mean (just reporting the most relevant cases) that it will be possible to create a Strigi krunner, have metadata extraction inside Dolphin and Konqueror, interact with Akonadi…

Talking about Xesam, right in these days I got a mail from Fabrice Colin, author of Pinot.
Recently Fabrice made some improvements on Pinot’s XesamQueryLanguage parser (which is also used by Strigi). We’re now figuring out how to share our code in a more convenient way. Maybe we’ll use svn external…

Since Strigi’s analyzer work in a different way, lot of code has to be ported. Unfortunately, after a good start, some relevant analyzers were still missing.

But in the last weeks Strigi gained support of:

• wave file
• avi files
• txt files
• dds files
• rgb files
• sid files
• ico files

I’ve also updated this summary page. As you can see there’s still some work to do, but don’t worry… I’ll try to do the best

So, by now, Strigi supports the following file system monitoring facilities:

• polling: used when nothing else is available
• inotify: available only on linux platform with kernel >= 2.6.13
• FAM: available on most of the *nix systems, I recommend to use Gamin instead of FAM (most linux distributions already use it by default)

But in the end I tamed the beast and now Xesam support in Strigi is full.

IMHO XesamUserSearchLanguage can be considered more important than XesamQueryLanguage since common users will write queries in this way.

As reported on the project page:
It is [XesamUserSearchLanguage] designed as an extended synthesis of Apple’s spotlight and Google’s search languages.

These are some possible queries (examples taken from freedesktop site):

• type:music hendrix will return all music items related to hendrix
• type:image size>=1mb tag:flower africa will return all pictures displaying a flower greater than 1 Mb and related with africa

Technical aspects

The Xesam’s UserSearchLanguage query–> Strigi::Query object conversion is made using a hand-written scanner and a C++ parser created by Bison.

You don’t have to worry if you don’t have Bison installed on your system since all parser generated code is already put into svn.

In these days, as soon as I’ll have some spare time (when?!), I’ll write another post about open-source scanner and parser generators.

By now I would like to thank Andreas Pakulat (developer of KDevelop) for his help with parser generators.

In the end yesterday I spent approximately four hours on the train. During this elapse of time I started the Xesam User Language parser

During the travels I:

• refreshed my memories about Flex, Bison and language parsers in general
• wrote XesamUserLanguage’s BNF grammar
• wrote Flex scanner
• started Bison parser

Now, after fixing some build errors, I’ll start writing Bison’s grammar rules. These rules will translate Xesam user language queries into Strigi::Query objects.

I hope it will work (both bathroom and Xesam parser )

Strigicmd is a command-line tool shipped with Strigi. It can perform different actions like:

• create Strigi indexes
• remove items from index
• list all files contained into an index
• retrieve informations associated to an indexed file
• update the contents of your index
• query the index
• perform a query using XesamQueryLanguage

So, if you want to try the new Xesam support you’ve just to use strigicmd with the xesamquery option.
The command syntax is:
strigicmd xesamquery -t backend -d indexdir [-u xesam_user_language_file] [-q xesam_query_language_file]
As you can expect you’ve to save your Xesam query to file and point strigicmd to it.

This is a really small step-by-step guide:

1. Create a new Strigi index (in this case I’ll index all irc logs):
   strigicmd create -t clucene -d temp/ logs/
2. Create a simple file containing your Xesam query. You can find some example query on Xesam site or inside strigi tarball (complete path: strigi/src/streamanalyzer/xesam/testqueries/).
   This is a stupid and easy query:

   <request>
   
   <query>
   
   <or>
   
   <equals>
   
   <string casesensitive="true">Oever</string>
   
   </equals>
   
   <contains>
   
   <string casesensitive="false">jos</string>
   
   </contains>
   
   </or>
   
   </query>
   
   </request>

3. Perform the search, just type:

   strigicmd xesamquery -t clucene -d temp/ -q ~/irc_oever.xml

4. Enjoy the search results

Remember that XesamUserLanguage query language isn’t yet supported.

But why is this important?

If you aren’t able to answer the previous question probably you don’t know what is Xesam.
Here’s a short definition taken from the official site:

Xesam is an umbrella project with the purpose of providing unified apis and specs for desktop search- and metadata services.

Thanks to dbus and Xesam it will be possible to access the informations indexed by Strigi (and all the desktop searching programs supporting these technologies) in a standard and easier way. Isn’t it cool?

Credits

I’ve to say a big “thank you” to Fabrice Colin (author of pinot) because my Xesam code relies upon his work.

Future tasks

My work isn’t yet finished. Xesam defines two kind of queries:

• Xesam user language queries
• Xesam query language queries

Fabrice’s code for XesamUserLanguage queries uses Spirit library. Since we don’t want to depend against the boost library, I’ll write a new parser for this language.

By now I’m thinking to accomplish this task using flex, but I’m just in a preliminary state.
Suggestions are welcome!

P.S. I’m really happy because this is my first post published on PlanetKDE. Hello to everybody!

These are the major changes introduced:

1. event caching: using a small cache it’s now possible to simplify multiple events and prevent high cpu usage when lot of changes occur on the same files
2. interruption handling during the re-index operations: changing the directories to watch during an indexing operation will break the previous job and start a new one
3. other small changes for improving cpu utilization

Actually I’m very happy of the first point, but I think the second one can still be improved…