Archive for the 'filesystems' Category

Understanding versus Knowing

June 28th, 2009 | Category: filesystems,microsoft,windows

When I went through high school we had three segments for our maths and physics exams: we had the basic knowledge part that tested if we new a given fact and could apply it to a straight forward problem, we had the understanding part that tested if we could understand a fact and apply it to a slightly more complex problem and we had a complex reasoning section of the exam which tested a combination of the items we knew and took a large number of steps to get to the final answer. Today I’m hunting around to look for file system permissions and I’ve read something that makes me wonder if there should be that distinction.

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Today, 14-Jan-08: Query languages, LDAP, business intelligence and filesystems

I’m going to start regularly writing daily posts about what I did today and the things I found interesting, I’ll at least try anyway.

First up for today is a personal thing, I completed a rather largish Uni assignment today which reminded me of all of the pains that come with C++, but to follow that I returned to working on my filesystem in C, which is just more pain. I got a quick response back, and almost full marks (96%) so I’m happy for all of the time I put in to get it done and how its probably far more complicated than anything else that will be submitted (it used Boost Signals and a whole heap of other things that I don’t think will ever be taught in the subject for a long time). But hey, thats just Uni!

Today I finally managed to get Pentaho, some business intelligence (BI) software, to play nicely with Novell eDirectory’s LDAP interface. I must have missed the option, but Pentaho doesn’t seem to accept anonymous binding to the LDAP server, which means I need to bind as a user. By default our users funnily enough have less access than the anonymous account (which is actually a proxy account with full browse permissions). The solution was simple enough: we shunted our dummy Pentaho user into the same group as the anonymous proxy account and everything worked. So I’ve now got Pentaho using LDAP for authentication (yay!) and a MySQL database to get its role/group permissions. Funnily enough when its all said and done the documentation is pretty close to the mark.

But once I had that I don’t have an ability to manage the groups/roles within Pentaho, so I end up having to write some small PHP to manage that. Luckily I worked on a project a while back that I called “Joomla! Central Management for Users” which basically connected directly to MySQL databases of Joomla! installs and altered the users. I had originally built it with a plugin infrastructure in mind so that I could plug other stuff into it later. Starting this morning it only had a ‘connector’ for Joomla! 1.0 via MySQL and LDAP, now it has one for the Pentaho security tables. This means I can easily copy users from LDAP or Joomla! into Pentaho without too much issues and has a debugged user interface already. But wait theres more!

When I was originally developing the tool I wrote a query language for it. See, SQL is a great language for databases, but its a bit hard to apply in situations where you don’t quite need all of that power. So I wrote my own query language. Its quite simple it can validate simple attributes and allows for set operations within “Sites” (a site is a container for users and groups). So for example I want to see all of the users who are on our web site but not in our LDAP directory:
existsin “Web Sites” and not existsin “LDAP”

Primitive sure, but it because writing a large SQL expression for something simple. I hope to expand on it, but it already does what it needs to do for the time being.

So I’ve covered query languages, LDAP and BI! All I need now is the filesystem news. Today there was a whole heap of fan fare on Slashdot about the ZFS news from Apple, whilst thats cool and all (especially since I don’t mind Apple’s UI), I personally have my own filesystem that I’ve gotten back into to do some work on. It also happens to be a Uni assignment due on Friday! So I’ll be back to working on that and hopefully I’ll have it to a nice stage that I can do some lightening talks at!

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Building a metadata filesystem

October 03rd, 2007 | Category: filesystems,mdfs,research

As part of my final year of studies at university I’m working on building a metadata filesystem, called “MDFS” or “MetaData FileSystem”. Creative naming don’t you think? The project is using FUSE to create the filesystem interface and PostgreSQL is used to store the data in the back end. Its in its early phases, but you can check it out here at a Trac instance I’ve created:

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