Saturday, 29 January 2011

The oddness of socks

In a moment of boredom, and prompted by a recent survey of wacky interview questions, I plotted out the probability graph of finding a matching pair of socks at random, based on the number of black ones among 25 grey ones. It turns out that you need only 3 black socks to drop the probability of a matching pair from 100% to 80%; 9 in 25 gets you to 60%. Anything over that makes very little difference up to 25, where the probability drops to a minimum as you would expect. After that it starts rising again slowly, but never reaches 100%. YOU NEVER HAVE A LESS THAN 48.9795918% CHANCE OF GETTING A MATCHING PAIR. I find that oddly comforting.

Friday, 14 January 2011

Oracle 10g problem under Windows Server 2003

It cost me the best part of two days' detective work to fix a problem with the Oracle DB Control service. Symptoms include:
  • "CONFIG: Waiting for service 'OracleDBConsoleorcl' to fully start" in cfgtoollogs\dbca\orcl\cloneDBCreation.log
  • "The oracleDBconsoleorcl service could not be started"
  • "[Orion Launcher] ERROR app.ContextInitializer contextInitialized.272 - Integration Class not found: oracle.sysman.ias.ias.IASIntegration" in emoms.log
This started to happen after a failed import using the data pump (impdp) trashed the database and I rashly thought that I might clear up the problem by uninstalling and reinstalling Oracle

Background: For a client project, we needed a local copy of the client's schema and stored procedures. I found it remarkably straightforward to install the Oracle product and a default database instance named orcl. However, attempting to import the client's exported schema and stored procs caused a rash of errors and then the SYSTEM user's password had been corrupted too. My suggestion: use the deprecated exp and imp tools instead. They're much more straightforward to use, AND the wonderful DDL Wizard is able to convert the exported file to DDL and PL/SQL that you can run in SQLPlus instead of overwriting your database contents willy-nilly.

Solution: I wish there was one. The problem appears to occur in the final phase of the database configuration assistant - after creating and configuring the database it tries to start up the console service for it and fails, for as-yet unfathomable reasons. Could it be to do with the fact that we also run MS SQL Server on the same box? Yet this was fine before I tried to reinstall Oracle. (As I eventually learned, I need not have redone the entire installation, because the database configuration assistant is quite good at deleting the database instance and creating a new one - in fact, this is what the installer invokes anyway).

Luckily the whole thing runs on a virtual machine, so I am going to get the previous week's VM backup image restored. Luckily we hadn't been doing a lot of work on that machine in the meantime.

My grateful thanks to the many bloggers who came up with possible solutions - none of which worked for me:

Wednesday, 12 January 2011

Software: Craft or Trade? You decide

Dan North has started a serious discussion with his insightful article about the Software Craftsmanship movement and where its manifesto possibly misses the point.

Thursday, 6 January 2011

Breaking up the big rocks

A colleague has circulated Richard Lawrence's nine patterns for dividing up user stories. These are going to be very useful. I wonder if someone will add more to make the magic Baker's Dozen?

New Ideas in Social Marketing

Attended a stunning event last night at the BCS London conference rooms. The speakers were Thomas Power of Ecademy and Lee Bryant of Headshift. The event was jointly organised by Richard Tandoh, Dalim Basu and Sara Misell on behalf of the North London Branch, Elayne Coakes on behalf of the BCS Sociotechnical specialist group and me on behalf of BCS Software Practice Advancement.

I learned that my use of social media was probably at the very raw beginner level - and moreover, that all the companies I have ever worked for, including my current employer, are at or below that level. If you want some insights into your level of influence measured by the effectiveness of your online behaviour (and how it compares to others), try Klout or PeerIndex. These applications use people's Twitter usernames as the primary key, so if you aren't on Twitter, you don't even get to first base.

Thomas showed how the stream of information we receive from the Web is growing exponentially - his FriendFeed home page was updating with new events more than once a second. A potentially incredibly useful tool for cutting this deluge down to size is made by My6Sense. They make a reader for iPhone, iPod Touch and Android devices that watches your Twitter, Facebook, News and RSS streams and brings the most important items to your attention. Thomas believes it takes around 30 hours to train it. More importantly, this being a social media world, once something has caught your attention, the my6sense app lets you share it easily with your own network of contacts.

In the Q&A session, I found out about a recently launched online service that is attempting to cross-fertilise a crowd-sourced knowledge repository (think Wikipedia) with a personal reputation index (like eBranding Me). A fun way to find out more is to take the Quora programming challenge.

The discussion in the pub afterwards was most illuminating too, though it veered away from social media to discussing the disaster that is likely to befall the civilised world when, not if, the next massive Coronal Mass Ejection occurs. This event is expected to occur within 10-24 months as of this writing and is likely to knock out not only communications networks (particularly satellite-based ones) but all manner of computer systems, data networks and power grids. Since everything these days is dependent on computers, we're likely to suffer supply shortages of everything from drinking water to fuel. As for withdrawing money from your bank account, you will probably be well advised to forget it for a few months. The guy telling us this has inside knowledge as a result of working for a major data security company and claims that they have working solutions to sell that will handle the backup and disaster recovery requirements of computer users from home users to data centres (remember that from the first detection of a CME, the world has only 15 minutes to secure everything before the plasma storm hits). His advice is to print out your bank statements and keep them safe along with non-perishable emergency supplies; also to have a spare laptop computer somewhere wrapped in several layers of tin foil to protect it from EMP. Contact me if you want to know more!

Monday, 3 January 2011

We need to re-learn that it's OK to fail

While trying to find the answer to a festive season quiz, I stumbled across this blog post. Check out the "more fialures" (sic) section - it makes reassuringly heartening reading...