Code Signs

AWS EMR Case Study with Hive

2010-10-27T11:42:00.000-07:00

To look into a great case study of using Hive on top of AWS' EMR, see here.

Dylib Architecture / Mac OS-X

2010-10-19T22:52:00.000-07:00

> file /usr/local/lib/libprotobuf.dylib
> /usr/local/lib/libprotobuf.dylib: Mach-O 64-bit dynamically linked shared library x86_64

Huawei Launches Digital Shopping Mall

2010-10-12T13:30:00.000-07:00

Huawei has launched its Digital Shopping Mall.

Deepwater Horizon, Siemens PLC and Stuxnet

2010-10-05T14:47:00.000-07:00

Stuxnet may have missed its target and may have caused other damage. Read F-Secure's Q&A regarding use of Siemens PLC in Deepwater Horizon.

Simple "Hello World" Using Grand Central Dispatch ( BSD , OS-X )

2010-10-05T08:34:00.001-07:00

Simple piece of GCD code:


#include "stdio.h"
#include <dispatch/dispatch.h>
#include <Block.h>

int main()
{

   dispatch_queue_t dq;

   dq = dispatch_queue_create("HelloWorld", NULL);

   dispatch_block_t block = ^{printf("===========Hello world.\n");};

   dispatch_async(dq,block);

   dispatch_main();

   return 0;
}

Shtting Down Stuxnet in Infected Systems

2010-10-01T16:17:00.000-07:00

A possible approach to remove Stuxnet is to create an anti-body superior in its "resilience" in comparison to the Stuxnet malware itself.

The anti-body should be just as "infective" if not more, i.e. it must be possible to have it installed in all relevant systems on the network, in a manner similar to Stuxnet itself.

Spreading like a manner similar to Stuxnet itself, and possiblly in a more viral manner, the anti-bodies will disable Stuxnet for garbage collection.

This seems like the best approach to me when it comes to super-infections. At least that's how it happens in our bodies.

Iran has made some interesting advances in drug invention and production.

I will not be surprised to see Iran become a leader or a leading partner in the production of cyber anti-bodies that work against malware from cyber criminals.

By the way, my conjecture is that those who created the Stuxnet -- whose operations are essentially akin to biological warfare -- have most probably also created some anti-bodies.

Of course, there's an art in creating anti-bodies and in immunology.

That same art needs to be applied here.

Project Lambda and JDK 1.7

2010-09-02T14:53:00.001-07:00

Project lambda is very cool, and developers cannot wait to see it released as part of the JDK.

Lucandra and HBasene

2010-06-01T00:05:00.000-07:00

HBasene . . . Lucene with HBase Backend for the Distributed Index . . .

Lucandra . . . Lucene with Cassandra Backend for Distributed Index . . .

Lucandra should give the best deal when it comes to ease of administration and operation. In the long-run it should also give very good performance, with some extra partitioning plug-in work as needed.

Rough Java Implementation of GCD

2010-05-31T14:26:00.000-07:00

Produced a rough Java implementation of Grand Central Dispatch APIs -- at this point, only the "classic" API forms, not the ones that rely on code block (or "closure") concept. JDK 6 doesn't support closures.

Lots of Tests with Casssandra

2010-05-31T14:22:00.000-07:00

I have been doing some tests comparing the speed of EC2 "local" file manipulation vs. speed of EC2 EBS volume file manipulation. The difference is significant. I have also been doing lots of tests with Cassandra, including some with Cassandra deployed on EC2 and on EC2 with EBS, all at AWS. Interesting results. Cassandra delivers most everything it promises as far as replication, partitioning and recovery are concerned. Pluggability of partitioning and replica placement strategies are a definite plus. It would be good to have some more pluggability in data file format and composition. This will be harder but worthwhile to accomplish.

Cassandra & Distributed File System

2010-02-19T15:31:00.000-08:00

Unlike HBase, Cassandra has no dependencies on a distributed file system. However, in a sense it implements a partitioned strategy that effectively replaces any (otherwise) required hard dependence on distributed file system capabilities.

This statement should not be taken as an endorsement of one or the other. Instead, it is simply an important architectural observation that directly impacts the overall system architecture.

Hadoop Combiners and Map-Reduce

2010-02-01T14:16:00.000-08:00

According to the Hadoop documentation, a Hadoop Combiner can be used to speedup Hadoop Map-Reduce if the Reduce function is both commutative and associative. It would be interesting to write a program that introspects a Hadoop Reduce function to draw a conclusion regarding the validity of this constraint for the use of Hadoop Combiner but it will not be trivial.

Cloud Computing--No Single Point of Failure

2010-01-19T12:55:00.000-08:00

A UC Berkeley technical report on cloud computing observes:

Just as large Internet service providers use multiple network providers so that failure by a single company will not take them off the air, we believe the only plausible solution to very high availability is multiple Cloud Computing providers. The high-availability computing community has long followed the mantra “no single source of failure,” yet the management of a Cloud Computing service by a single company is in fact a single point of failure. Even if the company has multiple datacenters in different geographic regions using different network providers, it may have common software infrastructure and accounting systems, or the company may even go out of business. Large customers will be reluctant to migrate to Cloud Computing without a business-continuity strategy for such situations. We believe the best chance for independent software stacks is for them to be provided by different companies, as it has been difficult for one company to justify creating and maintain two stacks in the name of software dependability

Read more of the report for other astute observations.

Design Principles for Modern Distributed Systems

2010-01-18T18:42:00.001-08:00

The design principles used for Amazon's S3 are generally applicable to modern distributed systems design. Quoting the S3 design principles:

Amazon S3 Design Principles

The following principles of distributed system design were used to meet Amazon S3 requirements:

Decentralization: Use fully decentralized techniques to remove scaling bottlenecks and single points of failure.

Asynchrony: The system makes progress under all circumstances.

Autonomy: The system is designed such that individual components can make decisions based on local information.

Local responsibility: Each individual component is responsible for achieving its consistency; this is never the burden of its peers.

Controlled concurrency: Operations are designed such that no or limited concurrency control is required.

Failure tolerant: The system considers the failure of components to be a normal mode of operation, and continues operation with no or minimal interruption.

Controlled parallelism: Abstractions used in the system are of such granularity that parallelism can be used to improve performance and robustness of recovery or the introduction of new nodes.

Decompose into small well-understood building blocks: Do not try to provide a single service that does everything for everyone, but instead build small components that can be used as building blocks for other services.

Symmetry: Nodes in the system are identical in terms of functionality, and require no or minimal node-specific configuration to function.

Simplicity: The system should be made as simple as possible (but no simpler).

Elasticity in Cloud Computing

2010-01-17T21:29:00.000-08:00

As Berkeley computer scientists have noted in a recent technical report, cloud computing (as utility) providers bring an economics where "using 1000 servers for one hour costs no more than using one server for 1000 hours." Economically, this translates into an elasticity of resources" without paying a premium for large scale ... unprecedented in the history of IT."

Interactive GAE / AWS application

2010-01-17T21:22:00.000-08:00

Out of pure curiosity, it would be interesting to build applications with applications parts interacting with both GAE and AWS at the same time.

Building PostgreSQL on Windows

2010-01-04T08:08:00.001-08:00

If you want to get and build PostgreSQL on Windows, try using the "git" repositories here. The repository that works with the anonymous cvs is apparently the root repository and the "git" ones are "mirrors" but it turns out that the root cvs repository has some Windows end-of-line characters that cause the build to fail. The repository you can access through "git" seems to be missing these and the build goes through. You need to ensure your cygwin installation includes readline, bison and flex.

A Brief Comparision of Concurrency in Grand Central Dispatch (GCD) and in Scala

2009-12-10T10:15:00.000-08:00

This is a first, brief note on the general similarities and differences in how concurrency constructs in Apple's GCD (Grand Central Dispatch) compare with similar constructs in Scala.

Both Scala and GCD require Closures / Code Blocks as well as Mutability / Immutability as the language-level foundation for their concurrency models.

Scala has supported closures (or code blocks) and mutability declarations as basic primitives in its more general functional extension to Java.
Apple has proposed the addition of elements to the C language that would bring support for code blocks and mutability to the standard C language. Apple has also modified the GCC 4.2 (C compiler) to accommodate the addition of these elements. Apple has made these modifications available under the MIT license. Apple has used these extensions in OS-X 10.6.

Both Scala and GCD support an event driven concurrency model.

Both Scala and GCD support "segmented programming". The segmented programming model is very popular and the accepted norm in GUI programming, where the developer implements, essentially, a series of call-backs that are called in response to various GUI events. Segmented programming model is an excellent model when we wish to support concurrent execution, as is often the case with GUI development. (For more on segmented programming model, see presentation Ulf Lange and I gave in Java One 2002.)

The major difference between GCD and Scala concurrency model is that GCD relies on dispatch/queue paradigm while Scala relies on message/actor paradigm.

I believe any complexity in using either GCD or Scala has to do primarily with learning the proper use of closures and immutability.

There are a few other things that separate GCD and Scala.

Scala is a natural evolution of Java as Java was a natural evolution of C or C++. For this reason, Scala provides familiar grounds to the Java programmer. It will be very familiar to Java programmers who are willing to learn about functional features as well as more complete static typing in Scala which helps with program conciseness. (As a Java programmer, I could not put down the first Scala book I picked up. All enhancements, modifications and changes that Scala has brought with respect to Java make sense, and the resulting conciseness in Scala proves to be a blessing when it comes to development work.)

GCD relies not only on the C language extension Apple has proposed (and the C compiler changes it has made available under a very permissive licensing model) but also on the specific APIs for GCD. These APIs are particular suited to the Objective-C and Mac OS-X environment. However, the major part of GCD API can be implemented in all environments and all of it will make sense in any Unix/Linux based system.

It would be good to see Apple's proposed changes to the C language adopted by the standards committee that looks over C.

Natural Evolution ...

2009-12-08T21:53:00.000-08:00

C-->C++-->Java-->Scala

Any, Nothing, Scala and Java

2009-12-03T08:52:00.001-08:00

The type verification engine in Scala outdoes the one in Java.

To enable this relative strength, Scala has defined, among other features, a closed type system, with the inclusion of "Any" and "Nothing".

"Any" is the super-type of all types. This is nothing new. Java has this, too, essentially speaking.

"Nothing" is the subtype of all types. When it comes to classic and modern type theory, there's nothing new about "Nothing" either. However, "Nothing"-ness is revolutionary new when thinking of how Java has treated types.

Java designers -- perhaps for the sake of the love of trees (I mean "trees" as a graph concept) and the love of "simplicity" of type system that characterizes OS and language designers wish to serve common programmers in general -- did not stipulate "Nothing". Had they done so, we would have had a completely different language in its characteristics from what became Java.

"Nothing" is a simple change but the consequences on the type system and language features are widespread.

Hadoop Tutorial in a virtual machine

2009-11-26T17:13:00.000-08:00

Cloudera virtual machine can be used to play with Hive and HDFS environment. See here.

Configuring Java and JDK on Snow-Leopard

2009-11-16T23:04:00.000-08:00

You can find the best explanations and backward configurations at http://wiki.oneswarm.org/index.php/OS_X_10.6_Snow_Leopard

Who says Java is slow?

2009-11-14T23:54:00.001-08:00

"Slowness of Java" proved to be a myth even back in 1996-1997, when Java ORBs kept beating C++ orbs in various RPC benchmarks.

Consider also, that in July 2008, Hadoop won the Terabyte Sort Benchmark: One of Yahoo's Hadoop clusters sorted 1 terabyte of data in 209 seconds. This beat the previous record of 297 seconds in the annual general purpose (Daytona) terabyte sort benchmark.

It was the first time that either a Java or an open source program had ever won.

Using SVN to find diffs on repositories

2009-05-28T14:44:00.001-07:00

Try something like the following :

svn diff -r779768:779000

which will produce file names and diffs between those two revision numbers of a code repository under svn control.

SOA . . . Is that All ?

2009-05-16T16:47:00.001-07:00

I originally wrote this entry on October 5, 2004, and published it on blogs.sun.com.

So, do I really get to cook SOA with these 10 ingredients? On ingredient number 6 (Governance), at least, I'd recommend another look.

Production or Maintenance & Support

2009-05-11T10:15:00.000-07:00

In The Cathedral & The Bazaar, Eric S. Raymond estimates that 75% to 90% of software business *effort* is not spent on the production of "products" but on support and maintenance of software products and systems. The sources of Raymond's claim are interesting in themselves ...

Bugs Lead to Existential Questions

2009-05-10T16:16:00.001-07:00

I originally wrote this entry on September 30, 2004, and published it on blogs.sun.com.

There are some who believe that we only switch from our "being" mode to our "thinking" mode of existence when something breaks down.

Let me give an example to make things clear.

Say, you're walking in Central Park in New York City towards a bench to sit for a moment.

As you do this, you're not constantly thinking: "Oh, this is a bench; now I'm 10 yards from it; it has 4 legs; it is painted green ; now I'm 4 hards from it; it is made of wooden planks and the legs are steel, etc. . . ." (Are Central Park benches green and made of wooden planks and steel? Or are they coming in concrete these days?)

If we thought in this fashion and of all these details, we'll go mad very quickly. Instead, we simply go and sit on the bench and enjoy the fresh air. That's what I like to call the "being" mode of existence.

Now, if the bench breaks beneath you as you sit, it will probably lead you to fall.

At that point, you will start going over everything that is supposed to make it a bench and wonder what went wrong, what "broke," what was not as it was to be. That's what I like to call the "thinking" mode of existence. A mode that deals with bugs in the existential environment.

So, it should be no wonder that the best way to start learning and thinking about existing, complex code and the process around its production, is to start by debugging it. Once the code is known and navigable, we become comfortable and at home, returning to the "being" mode. We become the code and know it as us.

Which mode is prior to the other? For which mode are we best tuned? Which is a "better" mode? Is code a place to be or a place to think? Is code even a place?

I don't know the answers to these questions.

What I do know is that every software engineer (or urban professional for that matter) needs to get out some times to see the world, take a bicycle ride (1, 2) or go on a simple stroll in the park, to sit on a bench, preferably made of wooden planks that won't break.

Open Source Society

2009-05-08T00:36:00.001-07:00

I originally wrote this entry on September 19, 2004 and published it on blogs.sun.com.

We (and this does not include just the U.S.) are already an open-source society to a very large extent. Information is widely available for those who care to find out and some have proven it possible to do so by their own example.

However, open dialogue matters well above and beyond open source.

Mixing, on the importance of which to innovation Lawerence Lessig has built a whole case, is simply an instance of open dialogue.

Open-source (widely available) information might be a pre-requisite for substantive dialogue but it neither replaces or guarantees it nor leads to it.

Finally, there're those who believe that what matters most is not cyber-dialogue but committed, emboddied dialogue and responsible action, as Hubert Dreyfus has noted in his analysis of the Internet.

Open Dialogue Code

2009-05-08T00:34:00.001-07:00

I originally wrote this entry on September 19, 2004 and published it on blogs.sun.com.

It's funny how certain corporate strategists pay more detailed attention to the press than to their own corporate purpose. (Some may even believe that all their problems stem from bad press.)

So, now we read in the reports (Reuters and the WSJ) that Microsoft has decided to open source its Office software to certain governments and under certain conditions. The same reports say that Microsoft has apparently done this to combat the advances of Linux, its "open-source" desk-top OS rival.

Under the program, Microsoft doesn't completely lift the veil. Governments are able to see 90% of the source code. The bulk of the rest is code where a third party owns the copyright, according to Microsoft. The company also holds back from exposing code that relates to antipiracy technology. (The WSJ, Sept. 20, 2004)

Even if source code is to be shared with more governments and under much less strict conditions, the strategic threat that Microsoft faces will persist. The problem is not an inability to see the code but an inability to participate in the dialog that ends up in it.

As I've said earlier, what matters is not openness of the source (whatever that means) but the openness of the dialogue about the source code, its use and evolution.

And here is another question worth thinking about. Would government regulations around the world ask for "open-source" code or "open-dialog" code? Most probably, it would be the former because "open-source" is a property more measurable.

A Real Student Bargain for JavaOne 2009

2009-04-17T01:40:00.000-07:00

This year, JavaOne let's students get in free!

Plus, they can sign up for CommunityOne at the same time.
Both passes are full conference passes with access to everything!
Educators can also get in free when they bring 10 students with them to the conference.
If they aren't able to do this, they still get a fantastic deal of $895 for a full conference pass.

What is a Full Pass?

All the benefits of a FULL conference attendee, which includes: JavaOne general and technical sessions, panel discussions, HOLs (Hands-on-labs), BOFs (Birds-of-a-feather), the Pavilion and the After Dark Bash / Networking Mixer! Not to mention a "hang space" (which includes video games, movies & more!), plus you will be able to check email any time at one of our many hacker stations.

PLUS

Admission to the CommunityOne Deep-Dives. What does this mean? FREE training by our very own SLS on some really great topics, plus hugely discounted certification (vouchers will be handed out at the event)- certification can even be done on-site! There will also be numerous parties and chances for you to network with the best and brightest in the industry, from community leaders to "Rockstars" and everyone in between.

Ideas from MySQL for Google Summer of Code 2009

2009-03-31T11:23:00.001-07:00

Check out the ideas from MySQL for Google Summer of Code 2009!

The Evolutionary Advantage of Open Source Software

2009-03-26T23:25:00.001-07:00

I originally wrote this entry on September 17, 2004, and published it on blogs.sun.com.

The evolutionary advantage of open source software rests not on the openness of the source code but on the openness of dialog it engenders, an openness which is often too hard to create without available, open source code.

Within the context of open dialog, learning occurs naturally, and ideas progress with minimal transaction costs.

Digital Rights Management, Where is the Big Question

2009-03-26T22:39:00.001-07:00

I originally wrote this entry on September 7, 2004, and published it on blogs.sun.com.

Digital

Rights Management (DRM) is one of the big technology questions web engineers have to deal with today. [For some introductory material, see this Australian Government guide to DRM. Also, ACM has held some workshops on DRM.]

In my view, a workable DRM system should allow some reasonable amount of content sharing. [See my notes on content sharing: To Share or Not to Share, That's the Question and To Share or Not to Share (II).]

Digital content distribution services continue to grow.

RealNetworks, for example, reports that its content business has grown more than 50% (at $99 million) while its enterprise software business has fallen by 14% (at $26 million). This shift in revenues goes back to 2000, the WSJ reports.

Many companies see their content services as a cash cow they need to protect at any cost. They are developing propriety systems that could be perceived as closed off to other content distribution systems. On the other hand, some may argue that distribution systems need to be protected to ensure their healthy evolution.

Looking to bridge that gap, RealNetworks recently introduced Harmony, a technology that lets consumers purchase songs on its RealPlayer Music Store site and transfer them to iPods or dozens of other players. Apple has threatened to sue RealNetworks and alter its technology to block such transfers.

(Marcelo Prince, The WSJ, Sept. 1, 2004.)

Is it in the interest of content owners for there to exist incompatible systems of content distribution and digital rights management?

This is a hard question to answer. On the one hand, more incompatibiltiy means greater barriers to wanton content sharing. On the other hand, more incompatibility may mean greater reluctance to join the digital music market as a buyer.

Finally, as I've said earlier, the most important question to ask in designing a DRM system, besides those very important questions related to limited-term copyright issues, is whether the system will allow some reasonable amount of content sharing.

Copyright extension

2009-03-17T21:57:00.001-07:00

I wrote this entry, originally, on June 30, 2004.

In Chapter 13 of his most recent book, Free Culture, the acclaimed Stanford Law Professor Lawrence Lessig has presented a critical evaluation of Sonny Bono Copyright Term Extension Act (CTEA) passed by the 105th Congress.

Lessig first provides a constitutional analysis of the copyright protection, emphasizing the part of the "Progress Clause" that stipulates a limited term for exclusive rights assigned to authors:

Congress has the power to promote the Progress of Science . . .
by securing for limited Times to Authors . . . exclusive Right
to their . . . Writings . . .
(Section 8, Clause 8 of the U.S. Constitution)

Lessig's basic point is that one cannot keep extending copyright protection and still remain faithful to the Progress Clause.

Lessig then notes that if we limit ourselves to the first 25 years of the works affected by CTEA, we see that only 2 percent of that work has any commercial value. (Lessig, p. 221)

Lessig describes how copyright term extensions can lead to disappearance of pieces of our culture which are of great significance but which may not be commercially active. He describes the high cost of obtaining copyright information regarding commercially inactive works and the legal risks of publishing them without clear findings on their copyright status. Those costs and risks, along the copyright extensions given by congress seem poised to lead to the disappearance of large chunks of American culture.

Of all creative work produced by humans anywhere, a tiny fraction
has continuing commercial value. For that tiny fraction, the copyright
is a crucially important legal device. For that tiny fraction, the
copyright creates incentives to produce and distribute the creative
work. For that tiny fraction, the copyright acts as an "engine of
free expression."

But even for that tiny fraction, the actual time during which the
creative work has a commercial life is extremely short . . . [M]ost
books go out of print within one year. The same is true of music and
film. Commerical culture is sharklike. It must keep moving. And when
a creative work falls out of favor with the commercial distributors,
the commercial life ends.

Yet that doesn't mean the life of the creative work ends. We don't
keep libraries of books in order to compete with Barnes & Noble,
and we don't have archives of films because we expect people to
choose between spending Friday night watching new movies and
spending Friday night watching a 1930 news documentary . . . To
understand who we are, and where we came from, and how we have made
mistakes that we have, we need to have access to this history.

MySQL Conference and Expo

2009-02-04T22:20:00.000-08:00

Just got this from a friend:

Registration for the 2009 MySQL Conference & Expo is now open! - April
20-23, 2009, Santa Clara, California. - Register by February 16, 2009, and
save $200!

www.mysqlconf.com

Sony Ericsson P1i support for Java

2007-10-21T20:51:00.000-07:00

Sony Ericsson covers some very good Java ground:

Both CDC and CLDC environments supported:
CLDC 1.1 JARs supported:
* JTWI 1.0 (JSR 185) consisting of Connected Limited Device
* Configuration (CLDC) 1.1 HI (JSR 139), MIDP 2.0 (JSR 118), WMA 1.1 (JSR 120)
* PDA Optional Packages (JSR 75)
* Bluetooth™ (JSR 82)
* Wireless Messaging API 2.0 (JSR 205)
* Web Services (JSR 172)
* Mobile Media API (JSR 135) Mobile 3D Graphics (JSR 184) with hardware acceleration
* Scalable 2D Vector Graphics API for J2ME (JSR 226)
* Nokia UI API 1.1
CDC 1.0 JARs supported:
* Foundation Profile 1.0 (JSR 46)
* Personal Profile 1.0 (JSR 62)
* PDA Optional Packages (JSR 75)

Mac OS-X Locking of Files

2007-05-28T14:27:00.000-07:00

I recently upgraded my iMac w/ iLife 06, which caused my iPhoto to have trouble loading the photo library. The reason was that some files in one of the photo library folders had been locked.

You can individually unlock files using the "GetInfo" command in Finder. There's a little box that needs to be unchecked in the "GetInfo" dialog box.

The fastest way to unlock file contents of a folder was the following script from the command terminal:

 sudo chflags -R nouchg .

The "." refers to the current folder in which the above command is being executed.

The sudo command is similar to a command with which Ubuntu users are also familiar.

Maintenance vs. Development

2007-05-15T22:44:00.001-07:00

For a colleague (Arun Gupta) who's looking into Ruby-on-Rails, I posted the following comment and question:

You might find APRESS' "Begining Ruby on Rails E-Commerce" useful. It covers quite a bit of ground while remaining focused on a full e-commerce application, containing all that is required in such applications, except perhaps, fancy user interfaces.
The question that arose in my mind as I read this book and played with the ideas contained in it was whether Ruby-on-Rails programs were any easier to maintain, and in general, what was the cost involved in maintaining them. Are we losing flexibility for maintenance as we gain speed of development?

I should have noted that the above book focus on using Ruby-on-Rails with MySQL. PostgreSQL also supports a relatively live and active Ruby-on-Rails community, particularly in Japan, I hear. Focusing on a particular DB supports that DB community. Note that the imposition of many relational constraints often require db-specific SQL. These DB specific SQL files can easily creep onto a Ruby-on-Rails project, defeating at least some aspect of its claim to DB independence.

Software & Economics

2007-05-15T22:42:00.000-07:00

It is good to see someone who has a relatively good understanding of Transaction Cost Economics write about the topic of open source software or software in general:

There was a time when a single determined individual could write the core of a single operating system for a primitive computer. But given the demands of computer applications and the capabilities of hardware technology at present, that is no longer conceivable. The task needs to be divided somehow. This immediately raises a ... core political economy question, about coordination of a division of labor within a centralized, hierarchical structure--that is, a firm. Within the firm an authority can make decisions about the division of labor and set up systems that transfer needed information back and forth between the individuals or teams that are working on particular chunks of the project. The boundaries of the firm are determined by make-or-buy decisions that follow from the logic of transaction cost economics. The system manages complexity through formal organization and explicit authority to make decisions within the firm as well as price coordination within markets between firms.

That's from Steven Weber's The Success of Open Source.

Foreign Keys and Views!

2007-02-04T22:36:00.000-08:00

In their Beginning Ruby on Rails E-Commerce, Christian Hellsten and Jarkko Laine use MySQL-specific SQL code to add foreign key constraints with cascading deletes to some of the tables defined using the ActiveRecord concepts. Having done so, and in order to enforce these constraints, they resort to incorporating code, in the "view" components of their application for adding objects to the tables. These additions to the already generated views ensure that the new objects posted to the database do not violate the foreign key constraints. I'm really not sure if there are other ways to define such constraints within Rails so that one does not need to use DB-specific SQL which obviously cannot be digested by ActiveRecord database migration tools. If there's no such alternative, I could be tempted to conclude that ActiveRecord has features that are mis-matched to some of the assumptions behind normalization principles of relational algebra. However, I should not be this judgmental yet. I've just begun to learn about Rails.

Tailing a log

2007-02-04T21:21:00.000-08:00

To tail a log file during tests of a Rails application, you can try "tail -f logs/test.log". If you do a "rake" of your project, this will show the beginning and rollback of various transactions against the test database.

About Rails

2007-02-04T21:11:00.000-08:00

Beginning Ruby on Rails E-Commerce, published by APRESS, provides a decent, practical introduction to Rails programming model, with a very useful example than runs through the book.

Apache / Derby and Java DB

2007-01-31T23:28:00.000-08:00

All the current uses of Apache / Derby (shipped as Java DB with the JDK, beginning with JDK 6) are truly astounding.

Development, The Agile Way

2007-01-30T23:32:00.000-08:00

Scrum is a light-weight agile software development process composed of Sprints, during which the next release of a system is being developed. To read about Scrum see ControlChaos and MountainGoatSoftware. (MountainGoatSoftware's Scrum page summarizes things quite nicely in the first paragraph on the top.)

Sun Microsystems Inc. Opens Java

2006-11-13T13:14:00.000-08:00

See my posts here and here.

On Web 2.0

2006-09-08T23:23:00.000-07:00

Here is what a recent Financial Times article says about Web 2.0 technologies:

The principle behind Web 2.0 is that millions of internet users come together in cyberspace to be part of online communities. This is driven by the ubiquity of the internet – a billion people are now online and many have access to relatively cheap high-speed internet.
There has also been a generational shift. Young people have grown up with the web and are willing to socialise and share personal information online.

Brevity and Ruby

2006-09-04T20:44:00.000-07:00

Code brevity can be a saving grace.

Containers, blocks, and iterators are core concepts in Ruby. The more you write in Ruby, the more you'll find yourself moving away from conventional looping constructs. Instead, you'll write classes that support iteration over their contents. And you'll find that this code is compact, easy to read, and a joy to maintain.

Dave Thomas, Programming Ruby: The Pragmatic Programmers' Guide, 2nd Edition, 2005 (page 57)

Learning to Program -- Code Sample

2006-08-07T14:13:00.000-07:00

Here's the Ruby code for the second exercise in "Mixing it Up" chapter of Chris Pine's Learn to Program

puts '=====Your favorite number======='
puts 'What\'s your favorite number?'
fnum=gets.chomp
puts 'Have you considered changing your favoriate number to '+x=(fnum.to_i+1).to_s
puts 'Why not choose the number '+x+' which is not only bigger but also better!'