The Hindu Business Line : Maintaining a network is like raising children

That sure puts a dose of affection into the exercise of taming an ever-errant network. So you can readily start with this book on hardware annoyances.

HOW to fix the most annoying things about your home network? For answer, look no further than a whole book on the subject: Home Networking Annoyances, by Kathy Ivens.

"Installing a network is easier than most people think, but maintaining a network is almost as much work as raising children. It seems to go on forever," she writes in the introduction.

Well, if that puts a dose of affection in the exercise of taming of an ever-errant network, you can readily start with `hardware annoyances'.

Have patience, however, because hardware devices can be `stubbornly non-communicative'.

Unlike software, hardware doesn't display error messages to help you determine what to do, writes Kathy, before taking questions head-on. Such as: "The back of my computer has a metal strip with two jacks, and the documentation says the computer has a PNA network adapter."

The abbreviation means `phoneline networking alliance', explains the author, and proceeds to a trickier question: "Our network currently consists of two computers in two adjacent bedrooms. I drilled a hole between those rooms to run cable between both computers and the router. Now we have to add another computer in a bedroom at the end of the hall (with a bathroom and a linen closet between the bedrooms that gets the new computer)."

If you have already figured out the rough plan in your head, there's more: "The router that connects the computers is in the bedroom closest to the new computer. I think the straightest run, using the least amount of cable, is to drill holes through each room... "

The chapter on software problems reflects the common frustrations. "There are all these tabs in the Properties dialog box, and each tab has many options. How am I supposed to know the correct selections?" asks one, while another wonders if he has to know `a ton of topics' including DNS settings, FTP, gateways, IP address and so forth.

"I move my laptop between my office, home network, four client sites, airport hot spots... well, you get the idea. I spend half my work life trying to configure my computer, and the other half dealing with error messages," frets yet another.

`The Fix' that Kathy offers for each of the queries has tips, warnings and also screenshots to help. Thus, to a baffled father who has to always find a computer that his kids aren't using, and finds the inconsistency of drive letters more annoying, the author advises that for mapping drives to favourite resources, he doesn't have to accept the next available drive letter.

"Pick a letter from the middle of the alphabet," she suggests, for achieving consistency.

"I want to configure a colour printer for black-and-white printing, but I can't for the life of me figure out how to do this. I've looked at every tab on the printer's Properties dialog box... " complains one query.

Kathy replies empathetically, "To perform this task you must go on a treasure hunt. To make matters worse, each printer model has its own maze, with entrance holes in different places. It's no wonder you're confused."

There are straightforward questions too. Such as, "How can you tell whether the firewall works properly?"

Test it, says the author. Check the site of Gibson Research Corporation (www.grc.com) , and "click the Shields Up!" What happens then?

"GRC attempts all sorts of tricks to break into your computer and then posts its results."

Humorous antidote to hassled users.

Collection of coherent data

IF you want to know database from scratch, try Database: Concepts and Systems, by Ivan Bayross. "A database can be defined as a collection of coherent (meaningful) data," starts Ivan and proceeds to explain the subject in a step-by-step manner, with the help of tables, examples and diagrams.

Relearn simple words that you might have taken for granted. For instance, if one were to ask an accountant what he meant by transaction, he'd talk in terms of debits and credits.

But Ivan dissects the word in the context of `business model' thus: "There are many occasions when multiple sub processes must complete successfully if master process is to be deemed successful. If a single sub process fails for any reason, the master process must be flagged as failed."

Thus several sub processes must pass or fail as a single unit of work, a.k.a. transaction, he'd add.

In the chapter on `relational model', encounter `relational algebra', which is defined as "a collection of operations that will manipulate data in a table". Relational algebra, a procedural language, is fully modelled in ANSI SQL, the natural lingo of RDBMS, informs Ivan.

Assuming you don't find it difficult to relate to these ideas, I can tell you about `relational calculus': "Tuple (i.e. various operations on the rows of a table) and domain (i.e. various operations on the values held in the columns of a table) calculi are referred to as relational calculus."

Lest you topple off, the author reassures: "The really great thing about all this is that a programmer need not know anything at all about relational calculus, predicate calculus or any other high level mathematical concepts to use an RDBMS."

Structured Query Language and SQL transactions are dealt with elaborately. There, you get to know the ACID properties, that is, atomicity, consistency, isolation, and durability of transaction; and the different `transaction states', viz. active, partially committed, failed, aborted, and committed.

What is a cursor? Check whether you know the answer that reads as follows: "The RDBMS Engine uses a work area (i.e. a specific place in the computer's memory) for all its internal processing." This work area is private to ANSI SQL's operations and is called cursor, explains Ivan.

"The data that is present in the cursor (i.e. data retrieved from a table or view) is called the active data set."

At the end of each chapter are dozens of review questions, including the objective ones to keep you active.

"The system is deadlocked if there is a set of transactions such that every transaction in the set is waiting for another transaction in the set," explains Ivan in the chapter on `concurrency control'.

While deadlocks are common in diplomacy and negotiation, we can't afford the same in database operations on which businesses depend.

So, there are strategies to prevent deadlocks, using `transaction timestamps'.

`Wait-die' scheme is one such, where "an older transaction may wait for younger one to release a data item," and younger transaction is rolled back.

Another is `wound-wait', in which "an older transaction wounds (forces rollback) of a younger transaction instead of waiting for it".

A book you can't wait to read, especially if you are in the database game.

(Books courtesy: Shroff Publishers www.shroffpublishers.com)

Tailpiece

"To help whistleblowers, our office set up a hi-tech alarm last week."

"How does it work?"

"Any staff can send an SMS to the device and that acts as a trigger for a shrill beep, all the while flashing the message but masking the sender's ID."

"Is it successful?"

"Oh, it's been shouting non-stop ever since inception!"

Books2Byte@TheHindu.co.in

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