named after a fighter...

Hi there, this weekend... we had to put our family dog Liston to sleep. He developed a tumor and after listening to 3 vets... we had no choice. Its sad to see him go like that. He is 10 years old now... kinda old for a dog.

We wanted it done humanely in our house... so we called Dr Ravi (from KKB) to come over. Liston somehow became worried cause the doctor could not locate the veins (he was a bit careless too) and bit the doctor (even though his mouth was tied). I had to hold him down and calm him... Liston looked so sad lah. After a short while he let go the last breath...

I still remember bringing him home from office... one of the secretaries in Scott Wilson (my first company) wanted to give away a baby doberman pinscher to me. He came to Rawang shivering... my Dad sat with him and patted him the whole night calming him. As for me... we had a love hate relationship... I did not like his con ways, trying to sneak inside everytime (only later I found out they were bred to be indoors)... but admired his intelligence and character.

He will be happier in dog heaven... I suppose.

Google Earth and all that buzzzzzz.....

Hi there, don't we just love Google Earth... I mean ... its awesome isn't it (http://earth.google.com/)??? Changes the way we look at maps and imagery. I installed it some time back ... and love to 'travel' or 'fly' whenever I am bored with work. I think GIS and non-GIS users are getting a kick using it. Its also got a lot of traditional GIS vendors (including ESRI) pointing fingers, scratching heads and comparing it with their own internet mapping products... its got the industry all excited and buzzing. Some are being defensive.

Well... after a little bit of research... okei, about 15 mins that is... gmail and google earth is actually based on something cool called AJAX. Ajax is a name given to a set of tools that previously existed in JavaScript. The main component is XmlHttpRequest, a class usable in JavaScript. It was around since IE4.0, can u believe that??The same concept was also named XmlHttp... okei, thats before the Ajax name became so commonly used.The use of XmlHttpRequest in 2005 by Google, in Gmail (yes... gmail too) and GoogleMaps has contributed to the success of this format. But this is the name Ajax itself that made the technology so popular... sweet!!!

There are some serious development using AJAX within ESRI... for ArcIMS and also ArcGIS Server. Read here:

http://forums.esri.com/Thread.asp?c=64&f=1333&t=170129#508529

http://forums.esri.com/Thread.asp?c=64&f=783&t=162354#504133

http://forums.esri.com/Thread.asp?c=64&f=783&t=175435#516915

http://forums.esri.com/Thread.asp?c=64&f=1333&t=159693#479501






















Actually... from what I can see and understand (in plain English)... AJAX is adding a new middleware between the client (your web browser) and the server (web server and database backend). This new middleware is placed on the client side.

The client user activity on his/her web browser leads to program calls on the client side... instead of sending the request each time to the server. The data transfer between the server and client uses XML. Cool... I think this is a solution to many applications that find it slow and demanding to communicate with the server... like ActiveX, Applets or even Flash.

storage disks... what is RAID??

Hi there, no one doubts that data and storage is core in any GIS implementation... especially in a government project that collects tons of data. Sometimes in GIS projects you hear about hardware or database vendors talking about disks and RAID configuration. It can get quite confusing... and you need to clearly understand the technical concept before you agree to any configuration.

Storage is expensive and decisions made must be clear and precise. It would be too late and way too expensive to change later.

So let me explain a bit on RAID technology (I get a lot of support calls on this) and some of the common configurations used:

• RAID 0 (also known as Disk Stripping) - This one requires minimum 2 drives and data written to the disk is broken down into blocks and each block written to seperate disks. The advantage of this is data becomes very fast... you are reading and writting data to multiple disks and the I/O is distributed. Just like walking into Public Bank and there are so many counters open... transactions are faster. The disadvantage of RAID 0 is ... when a single or more drive fails... thats it... the entire array is corrupted and you are screwed.
• RAID 1 - This one requires minimum 2 (with multiples of 2). All data written to storage system is replicated to 2 physical disks, providing good redundancy. This is a reliable configuration assuming a single disk per pair fails... but performance can suffer for writting data because it has to write to 2 drives. Actually it depends on the kind of application you are using... cause if its gonna be high updates on data all the time... concurrently... then there might be other RAID levels to choose. I like RAID 1 actually.
• RAID 3 (Parallel transfer disks with parity) - This one requires a minimum of 3 drives. Data is broken into byte level and evenly written across data disks. It tolerates the loss of a single drive. Reasonable sequential write performance. Good sequential read performance. However, its rarely used, so troubleshooting information could be sparse. Requires hardware RAID to be truly viable. RAID 3 is generally considered to be very efficient. Poor random write performance. Fair random read performance.
• RAID 4 (Independent data disks with shared parity blocks) - A file is broken down into blocks and each block is written across multiple disks, but not necessarily evenly. Like RAID 3, RAID 4 uses a separate physical disk to handle parity. Excellent choice for environments in which read rate is critical for heavy transaction volume. Drives required (minimum): 3 Pros: Very good read rate. Tolerates the loss of a single drive. Cons: Write performance is poor. Block read performance is okay.
• RAID 5 (Independent access array without rotating parity) - Minimum drives required is 3. Blocks of data are written across sets of disks… but parity (storage info)… is kept with the rest of the data. This is the most popular RAID and tolerates the loss of a single drive. So everytime data is written, parity info (storage metadata) is stored together… which sometimes can cause slowness… but its bearable.
• RAID 6 (Independent Data disks with two independent distributed parity schemes) - Blocks of data are written to entire set of disks… it could be uneven too. Minimum drives required is 3. This config can tolerate up to 2 drives loss. Its mainly used for high end applications where storage is really mission critical. Very rare in GIS, unless its military applications.

Parity - In certain RAID levels, redundancy is achieved by the use of parity blocks. If a single drive in the array fails, data blocks and a parity block from the working drives can be combined to reconstruct the missing data.

happy anniversary?? for whom...

I still remember being awestruck and excited with all things "computers" when it was introduced in my secondary school (Sekolah Menengah Seri Garing, Rawang... also fondly called SEGAR). I was 14 then... waiting for school to end... and then quickly run to the lab and book a seat. Manjit Singh was my instructor then, cool dude. It was an IBM pc, I think. That started my passion with all things IT. I begged my cousin to lend his Atari, it ended up being mine. I also loved the Amiga machines. When it came... I took a bus to Imbi plaza and gawked at its interface... cool colours and interesting OS.

Which brings us to Apple!!! Apple PC to me ... was like the BMW of computers then (maybe even now)... always one step ahead of everyone else in terms of ideas and innovation. Steve Jobs and Steve Wozniak started Apple on April Fool's Day 1976, its already 30 years now. There has been a lot of ups and downs for Apple. Throughout, I have tested it at friends places, computer labs and even at computer shops. To be honest, I never really liked it... either it was too expensive, has too many niche software, ugly casing and caters for a cult group of fans. All its cool ideas were improved by others... especially that big copy-cat Bill Gates. In campus... Windows was the 'in-thing', it had a cool interface... many people were excited they can play VCDs and computer games... but to me... thats just an Apple clone lah dude. However.. unlike Apple... Microsoft learns fast from their mistakes. Since then, Windows has improved so much leaving all their competitors far... far... behind.

My interest as a kid... were just games and BASIC programming. Even now, Apple seems to have this special group of users... iPod and all... something I would never buy. No.. don't get me wrong... this time I can afford to get one, love MP3s and all that cool downloads. But its a gadget not worth having... doesn't fit into my lifestyle I suppose. I wasn't into that Sony Walkman thing too... after a while you get bored. I rather spend that money on a Playstation.

Now we hear that Apple will be using Windows as its O/S. Huh?? It does not make sense. All through these years the Apple O/S has always stuck close to UNIX 'roots'... champions of a cause. Moving into Windows is just gonna proof that something is wrong. OK, I dun like Windows too... but all this domination and sharing is just leaving me more confused ;-)