Upgrading to Windows 6.1 a.k.a. Windows 7 10:10 AM Oct 31st
Updated XO laptops to the latest OS version: 8.2.1. Nice! If you don't know it, you can think of the OLPC as a rugged netbook for kids. 9:39 AM Oct 29th
Just created twitter lists. Nice implementation :-) 9:30 AM Oct 29th
OO Wisdom from Head First Design Patterns http://bit.ly/13LmkU 4:51 PM Oct 24th
Yesterday, a great italian dinner at Paço de Arcos. Today, a very good sushi lunch at S.J. Deus. It can't get any better! 1:14 PM Oct 23rd
RT @nunodelisboa Novo Governo: http://bit.ly/ppJWE 7:24 PM Oct 22nd
Writing specs document because putting ideas on paper is usually a good idea! 7:20 PM Oct 22nd
This afternoon I'm working in a very nice office, with Van Gogh and Dali paintings 2:55 PM Oct 22nd
Visualize the invisible in RFID http://bit.ly/YcHJY 9:19 AM Oct 21st
It's raining. A lot! 8:40 AM Oct 20th
Tidying up my desktop - the physical one ;-) 9:57 AM Oct 19th
The STEP Framework is now updated to Java 6, Tomcat 6. It also has many small improvements. 12:25 AM Oct 18th
Working today to recover the time lost because of a JAX-WS bug! Moving forward now. 4:52 PM Oct 17th
@nfma Google wave... I also want an invitation! 11:09 AM Oct 16th in reply to nfma
Errands in the morning. The river Tejo is always a delight on a sunny day! 2:54 PM Oct 14th
Getting close to fixing a bug that has cost me almost 3 days of work (so far) 3:19 PM Oct 13th
Rissóis de Leitão ao almoço. Estranho mas bem saboroso! 1:30 PM Oct 13th
A solar-powered e-reader! Very interesting idea. http://bit.ly/mkVTD 10:27 AM Oct 13th
Now that elections season is over let's all get back to work! :-) 10:54 AM Oct 12th
Nobel da Paz para Obama!? Mas ele ainda não fez nada! Inacreditável... 11:54 AM Oct 9th
Setting up a Fosstrak EPCIS repository http://www.fosstrak.org/ 9:55 AM Oct 9th
Just checked that Sleeping Beauty is OK. She'll have to wake soon, though. 7:24 PM Oct 8th
I won't give up on JF 5:56 PM Oct 8th
JF: "O pior cego é o que não quer ver" 10:31 AM Oct 8th
Hope is almost lost for JF... I can't help when my help is not wanted. Sad... Really sad... God help him. 6:55 PM Oct 7th
Fighting with a nasty software bug 4:45 PM Oct 7th
Updated my DeskSpace software. Now it's easier to work with separate desktops for the editor and the "engine room" (server logs) 12:02 PM Oct 7th
"Hello friend!" Hacked for hours to get this message working again :-) 7:22 PM Oct 6th
Today was the first rainy day in Lisbon. The Fall has arrived! 9:57 PM Oct 5th
Working today despite the holiday. I guess I'm not a Republic enthusiast :-) 3:45 PM Oct 5th
Just had a nice sushi lunch near Técnico. 1:25 PM Oct 2nd
@pedrocustodio STEMI for me (Science, Technology, Engineering, Math and Intuition) :-) 9:48 AM Oct 2nd in reply to pedrocustodio
Good morning! A new day starting, again at Taguspark. Lots of interesting work for today. 9:08 AM Oct 1st
2009-10-31
2009-10-30
2009-10-28
High-Performance with Virtualization
There are two types of HPC virtualization:
Scale-up Virtualization - a single hypervisor runs across multiple computers. This aggregates multiple CPUs and memory systems and makes them appear as a single computer. It is best for applications that require a lot of memory.
Scale-out Virtualization - a VM and hypervisor run on every processor core in each machine in the virtual supercomputer. A grid-management tool, rather than a single hypervisor as in scale-up HPC virtualization, manages the overall system. It is best for processor-intensive applications.
Read the full article from IEEE Computing Now.
P.S. - An hypervisor is the software that allocates a host machine's resources to each virtualized operating system or to each program running on a virtualized OS.
Scale-up Virtualization - a single hypervisor runs across multiple computers. This aggregates multiple CPUs and memory systems and makes them appear as a single computer. It is best for applications that require a lot of memory.
Scale-out Virtualization - a VM and hypervisor run on every processor core in each machine in the virtual supercomputer. A grid-management tool, rather than a single hypervisor as in scale-up HPC virtualization, manages the overall system. It is best for processor-intensive applications.
Read the full article from IEEE Computing Now.
P.S. - An hypervisor is the software that allocates a host machine's resources to each virtualized operating system or to each program running on a virtualized OS.
Day Without Yesterday quote
The writers of the Bible were illuminated more or less – some more than others – on the question of salvation. On other questions they were as wise or as ignorant as their generation. Hence it is utterly unimportant that errors of historic or scientific fact should be found in the Bible, especially if errors relate to events that were not directly observed by those who wrote about them.
The idea that because they were right in their doctrine of immortality and salvation they must also be right on all other subjects is simply the fallacy of people who have an incomplete understanding of why the Bible was given to us at all.Georges Lemaître, answering a question in a 1933 interview (How does a priest-physicist reconcile his faith with his science?)
The Day Without Yesterday, Lemaître, Einstein and the birth of modern cosmology
2009-10-26
Exploding Software-Engineering Myths
Some people at Microsoft Research are on a quest to validate conventional software-engineering wisdom. So far they have found evidence for:
- More Isn't Always Better
- Write Test Code First
- Proving the Utility of Assertions
- Organizational Structure Does Matter - a Lot
- Geographical Distance Doesn’t Matter - Much
Read the full article.
- More Isn't Always Better
- Write Test Code First
- Proving the Utility of Assertions
- Organizational Structure Does Matter - a Lot
- Geographical Distance Doesn’t Matter - Much
Read the full article.
2009-10-24
OO Wisdom
OO Basics
Abstraction
Encapsulation
Polymorphism
Inheritance
OO Principles
Encapsulate what varies
Favor composition over inheritance
Program to interfaces, not to implementations
Strive for loosely coupled designs between objects that interact
Classes should be open for extension but closed for modification
Depend on abstractions. Do not depend on concrete classes.
Only talk to your friends.
Don't call us, we call you.
A class should have only one reason to change.
Patterns' description
Abstract Factory - Allows a client to create families of objects without specifying their concrete classes
Adapter - Wraps an object and provides a different interface to it
Command - Encapsulates a request as an object
Composite - Clients treat collections of objects and individual objects uniformly
Decorator - Wraps an object to provide new behavior
Facade - Simplifies the interface of a set of classes
Factory Method - Subclasses decide which concrete classes to create
Iterator - Provides a way to traverse a collection of objects without exposing its implementation
Observer - Allows objects to be notified when state changes
Proxy - Wraps an object to control access to it
Singleton - Ensures one and only object is created
State - Encapsulates state-based behaviors and uses delegation to switch between behaviors
Strategy - Encapsulates interchanging behaviors and uses delegation to decide which one to use
Template method - Subclasses decide how to implement steps in an algorithm
Other patterns
Bridge - use to vary not only your implementations, but also your abstractions
Builder - use to encapsulate the construction of a product and allow it to be constructed in steps
Chain of Responsibility - use when you want to give more than one object a chance to handle a request
Flyweight - use when one instance of a class can be used to provide many "virtual instances"
Interpreter - use to build an interpreter for a language
Mediator - use to centralize complex communication and control between related objects
Memento - use when you need to be able to return an object to one of its previous states ("undo")
Prototype - use when creating an instance of a given class is either expensive or complicated
Visitor - use when you want to add capabilities to a composite of objects and encapsulation is not important
--
Read more about Design Patterns in the great book: Head First Design Patterns. I highly recommended it for all programmers with more than 2 years of experience.
Abstraction
Encapsulation
Polymorphism
Inheritance
OO Principles
Encapsulate what varies
Favor composition over inheritance
Program to interfaces, not to implementations
Strive for loosely coupled designs between objects that interact
Classes should be open for extension but closed for modification
Depend on abstractions. Do not depend on concrete classes.
Only talk to your friends.
Don't call us, we call you.
A class should have only one reason to change.
Patterns' description
Abstract Factory - Allows a client to create families of objects without specifying their concrete classes
Adapter - Wraps an object and provides a different interface to it
Command - Encapsulates a request as an object
Composite - Clients treat collections of objects and individual objects uniformly
Decorator - Wraps an object to provide new behavior
Facade - Simplifies the interface of a set of classes
Factory Method - Subclasses decide which concrete classes to create
Iterator - Provides a way to traverse a collection of objects without exposing its implementation
Observer - Allows objects to be notified when state changes
Proxy - Wraps an object to control access to it
Singleton - Ensures one and only object is created
State - Encapsulates state-based behaviors and uses delegation to switch between behaviors
Strategy - Encapsulates interchanging behaviors and uses delegation to decide which one to use
Template method - Subclasses decide how to implement steps in an algorithm
Other patterns
Bridge - use to vary not only your implementations, but also your abstractions
Builder - use to encapsulate the construction of a product and allow it to be constructed in steps
Chain of Responsibility - use when you want to give more than one object a chance to handle a request
Flyweight - use when one instance of a class can be used to provide many "virtual instances"
Interpreter - use to build an interpreter for a language
Mediator - use to centralize complex communication and control between related objects
Memento - use when you need to be able to return an object to one of its previous states ("undo")
Prototype - use when creating an instance of a given class is either expensive or complicated
Visitor - use when you want to add capabilities to a composite of objects and encapsulation is not important
--
Read more about Design Patterns in the great book: Head First Design Patterns. I highly recommended it for all programmers with more than 2 years of experience.
Films picked up by Vatican: Art
Art:
2001: A Space Odyssey (Stanley Kubrick, 1968) "It says that man is just a tiny nothing on the stairway to paradise; something better (i.e., non-human) is coming, and it's all out of your hands anyway. Kubrick's story line—which accounts for evolution by an extraterrestrial intelligence—is probably the most gloriously redundant plot of all time." — Pauline Kael
"The genius is not in how much Stanley Kubrick does in 2001: A Space Odyssey, but in how little. This is the work of an artist so sublimely confident that he doesn't include a single shot simply to keep our attention. He reduces each scene to its essence, and leaves it on screen long enough for us to contemplate it, to inhabit it in our imaginations. Alone among science-fiction movies,2001 is not concerned with thrilling us, but with inspiring our awe." — Roger Ebert
"A milestone film: space travel is placed into context of man's history, from first confrontation with a Greater Power to future time warp where life cycle has no meaning." — Leonard Maltin
La Strada (Federico Fellini, 1954) "The theme of Federico Fellini's spiritual fable is that everyone has a purpose in the universe ... Even if one rejects the concepts of this movie, its mood and the details of scenes stay with one; a year or two later, a gesture or a situation suddenly brings it all back." — Pauline Kael
Citizen Kane (Orson Welles, 1941) "The Orson Welles film is generally considered the greatest American film of the sound period, and it may be more fun than any other great movie. Based on the life of William Randolph Hearst, it's an exuberant, muckraking attack on an archetypal economic baron." — Pauline Kael
Metropolis (Fritz Lang, 1926) "H.G. Wells called this German silent 'quite the silliest film'; Hitler was so impressed by the conception that many years later he tried (unsuccessfully) to persuade its director, Fritz Lang, to make Nazi movies ... One of the last examples of the imaginative—but often monstrous—grandeur of the Golden Period of the German film, Metropolis is a spectacular example of Expressionist design (grouped human beings are used architecturally), with moments of almost incredible beauty and power (the visionary sequence about the Tower of Babel), absurd ineptitudes (the lovesick hero in his preposterous knickerbockers), and oddities that defy analysis (the robot vamp's bizarre, lewd wink). It's a wonderful, stupefying folly." — Pauline Kael
"One of the great achievements in the silent era, a work so audacious in its vision and so angry in its message that it is, if anything, more powerful today than when it was made." — Roger Ebert
Modern Times (Charlie Chaplin, 1936) "After City Lights, which was silent, with a musical accompaniment and sound effects, Charlie Chaplin was absent from the screen for five years; he returned in triumph with this rambunctious comedy in which he still doesn't speak, although he uses background sounds and, as a singing waiter in a crowded cabaret, he does a wonderful jabberwocky patter song that you can't get out of your head. (It is, of course, a demonstration of how unnecessary words are.)" — Pauline Kael
Napoleon (Abel Gance, 1927) "Abel Gance originally made it as a 6-hour silent film, in color (the prints were tinted and toned by a dye process), and with sections designed to be run on a triple-width screen, by a process called Polyvision. His conception was far more complex than what directors later did with Cinerama, since Gance frequently used the images at the left and right of the central image for contrapuntal effects—history became an avalanche of armies, battles, and crowds. The film is both avant-garde and old-fashioned." — Pauline Kael
8 ½ (Federico Fellini, 1963) "A long, difficult, but fascinating film, overflowing with creative and technical wizardry. Certainly one of the most intensely personal statements ever made on celluloid." — Leonard Maltin
Grand Illusion (Jean Renoir, 1937) "In form, Grand Illusion is an escape story; yet who would think of it in this way? It's like saying that Oedipus Rex is a detective story. Among other things, this film is a study of human needs and the subtle barriers of class among a group of prisoners and their captors during the First World War." — Pauline Kael
Nosferatu (F.W. Murnau, 1922) "To watch F.W. Murnau's Nosferatu is to see the vampire movie before it had really seen itself. Here is the story of Dracula before it was buried alive in cliches, jokes, TV skits, cartoons and more than 30 other films. The film is in awe of its material. It seems to really believe in vampires." — Roger Ebert
"The original, superbly loathsome German version of Bram Stoker's novel Dracula is a concentrated essay in horror fantasy, full of weird, macabre camera effects. Though ludicrous at times (every horror film seems to become absurd after the passage of years, and many before—yet the horror remains), this first important film of the vampire genre has more spectral atmosphere, more ingenuity, and more imaginative ghoulish ghastliness than any of its successors. The movie often seems more closely related to demonic painting than to the later, rather rigid vampire-movie genre." — Pauline Kael
Stagecoach (John Ford, 1939) "Perhaps the most likable of all Westerns, and a Grand Hotel-on-wheels movie that has just about everything—adventure, romance, chivalry—and all of it very simple and traditional." — Pauline Kael
"One of the great American films, and a landmark in the maturing of the Western, balancing character study ... and peerless action. . ." — Leonard Maltin
The Leopard (Luchino Visconti, 1963) "Magnificent—a sweeping popular epic, with obvious similarities to Gone With the Wind, and with an almost Chekhovian sensibility." — Pauline Kael
Fantasia (Walt Disney, 1940) "Initially, the film was a box—office failure, but it proved successful in revivals, especially in the early 70s, when it became a popular head film, because of such ingredients as the abstract first section, the mushroom dance during 'The Nutcracker' (one of the liveliest sequences), and the overly bright—somewhat psychedelic—color. 'The Sorcerer's Apprentice,' featuring Mickey Mouse, and parts of other sequences are first-rate Disney, but the total effect is grotesquely kitschy." — Pauline Kael
The Wizard of Oz (Victor Fleming, 1939) "It somehow seems real and important in a way most movies don't. Is that because we see it first when we're young? Or simply because it is a wonderful movie? Or because it sounds some buried universal note, some archetype or deeply felt myth?
"I lean toward the third possibility, that the elements in ``The Wizard of Oz'' powerfully fill a void that exists inside many children. For kids of a certain age, home is everything, the center of the world. But over the rainbow, dimly guessed at, is the wide earth, fascinating and terrifying. There is a deep fundamental fear that events might conspire to transport the child from the safety of home and strand him far away in a strange land. And what would he hope to find there? Why, new friends, to advise and protect him. And Toto, of course, because children have such a strong symbiotic relationship with their pets that they assume they would get lost together.
This deep universal appeal explains why so many different people from many backgrounds have a compartment of their memory reserved for The Wizard of Oz.'' — Roger Ebert
"A genuine American classic ... Just as good the fifteenth time as it is the first time." — Leonard Maltin
The Lavender Hill Mob (Charles Crichton, 1951) "It's a minor classic, a charmer." — Pauline Kael
Little Women (George Cukor, 1933) "There are small flaws—a few naïve and cloying scenes, some obvious dramatic contrivances—but it's a lovely, graceful film, and surprisingly faithful to the atmosphere, the Victorian sentiments, and the Victorian strengths of the Louisa May Alcott novel." — Pauline Kael
--
That was it: 45 good suggestions! I hope you enjoyed them and, of course, comment with some of your own!
2001: A Space Odyssey (Stanley Kubrick, 1968) "It says that man is just a tiny nothing on the stairway to paradise; something better (i.e., non-human) is coming, and it's all out of your hands anyway. Kubrick's story line—which accounts for evolution by an extraterrestrial intelligence—is probably the most gloriously redundant plot of all time." — Pauline Kael
"The genius is not in how much Stanley Kubrick does in 2001: A Space Odyssey, but in how little. This is the work of an artist so sublimely confident that he doesn't include a single shot simply to keep our attention. He reduces each scene to its essence, and leaves it on screen long enough for us to contemplate it, to inhabit it in our imaginations. Alone among science-fiction movies,2001 is not concerned with thrilling us, but with inspiring our awe." — Roger Ebert
"A milestone film: space travel is placed into context of man's history, from first confrontation with a Greater Power to future time warp where life cycle has no meaning." — Leonard Maltin
La Strada (Federico Fellini, 1954) "The theme of Federico Fellini's spiritual fable is that everyone has a purpose in the universe ... Even if one rejects the concepts of this movie, its mood and the details of scenes stay with one; a year or two later, a gesture or a situation suddenly brings it all back." — Pauline Kael
Citizen Kane (Orson Welles, 1941) "The Orson Welles film is generally considered the greatest American film of the sound period, and it may be more fun than any other great movie. Based on the life of William Randolph Hearst, it's an exuberant, muckraking attack on an archetypal economic baron." — Pauline Kael
Metropolis (Fritz Lang, 1926) "H.G. Wells called this German silent 'quite the silliest film'; Hitler was so impressed by the conception that many years later he tried (unsuccessfully) to persuade its director, Fritz Lang, to make Nazi movies ... One of the last examples of the imaginative—but often monstrous—grandeur of the Golden Period of the German film, Metropolis is a spectacular example of Expressionist design (grouped human beings are used architecturally), with moments of almost incredible beauty and power (the visionary sequence about the Tower of Babel), absurd ineptitudes (the lovesick hero in his preposterous knickerbockers), and oddities that defy analysis (the robot vamp's bizarre, lewd wink). It's a wonderful, stupefying folly." — Pauline Kael
"One of the great achievements in the silent era, a work so audacious in its vision and so angry in its message that it is, if anything, more powerful today than when it was made." — Roger Ebert
Modern Times (Charlie Chaplin, 1936) "After City Lights, which was silent, with a musical accompaniment and sound effects, Charlie Chaplin was absent from the screen for five years; he returned in triumph with this rambunctious comedy in which he still doesn't speak, although he uses background sounds and, as a singing waiter in a crowded cabaret, he does a wonderful jabberwocky patter song that you can't get out of your head. (It is, of course, a demonstration of how unnecessary words are.)" — Pauline Kael
Napoleon (Abel Gance, 1927) "Abel Gance originally made it as a 6-hour silent film, in color (the prints were tinted and toned by a dye process), and with sections designed to be run on a triple-width screen, by a process called Polyvision. His conception was far more complex than what directors later did with Cinerama, since Gance frequently used the images at the left and right of the central image for contrapuntal effects—history became an avalanche of armies, battles, and crowds. The film is both avant-garde and old-fashioned." — Pauline Kael
8 ½ (Federico Fellini, 1963) "A long, difficult, but fascinating film, overflowing with creative and technical wizardry. Certainly one of the most intensely personal statements ever made on celluloid." — Leonard Maltin
Grand Illusion (Jean Renoir, 1937) "In form, Grand Illusion is an escape story; yet who would think of it in this way? It's like saying that Oedipus Rex is a detective story. Among other things, this film is a study of human needs and the subtle barriers of class among a group of prisoners and their captors during the First World War." — Pauline Kael
Nosferatu (F.W. Murnau, 1922) "To watch F.W. Murnau's Nosferatu is to see the vampire movie before it had really seen itself. Here is the story of Dracula before it was buried alive in cliches, jokes, TV skits, cartoons and more than 30 other films. The film is in awe of its material. It seems to really believe in vampires." — Roger Ebert
"The original, superbly loathsome German version of Bram Stoker's novel Dracula is a concentrated essay in horror fantasy, full of weird, macabre camera effects. Though ludicrous at times (every horror film seems to become absurd after the passage of years, and many before—yet the horror remains), this first important film of the vampire genre has more spectral atmosphere, more ingenuity, and more imaginative ghoulish ghastliness than any of its successors. The movie often seems more closely related to demonic painting than to the later, rather rigid vampire-movie genre." — Pauline Kael
Stagecoach (John Ford, 1939) "Perhaps the most likable of all Westerns, and a Grand Hotel-on-wheels movie that has just about everything—adventure, romance, chivalry—and all of it very simple and traditional." — Pauline Kael
"One of the great American films, and a landmark in the maturing of the Western, balancing character study ... and peerless action. . ." — Leonard Maltin
The Leopard (Luchino Visconti, 1963) "Magnificent—a sweeping popular epic, with obvious similarities to Gone With the Wind, and with an almost Chekhovian sensibility." — Pauline Kael
Fantasia (Walt Disney, 1940) "Initially, the film was a box—office failure, but it proved successful in revivals, especially in the early 70s, when it became a popular head film, because of such ingredients as the abstract first section, the mushroom dance during 'The Nutcracker' (one of the liveliest sequences), and the overly bright—somewhat psychedelic—color. 'The Sorcerer's Apprentice,' featuring Mickey Mouse, and parts of other sequences are first-rate Disney, but the total effect is grotesquely kitschy." — Pauline Kael
The Wizard of Oz (Victor Fleming, 1939) "It somehow seems real and important in a way most movies don't. Is that because we see it first when we're young? Or simply because it is a wonderful movie? Or because it sounds some buried universal note, some archetype or deeply felt myth?
"I lean toward the third possibility, that the elements in ``The Wizard of Oz'' powerfully fill a void that exists inside many children. For kids of a certain age, home is everything, the center of the world. But over the rainbow, dimly guessed at, is the wide earth, fascinating and terrifying. There is a deep fundamental fear that events might conspire to transport the child from the safety of home and strand him far away in a strange land. And what would he hope to find there? Why, new friends, to advise and protect him. And Toto, of course, because children have such a strong symbiotic relationship with their pets that they assume they would get lost together.
This deep universal appeal explains why so many different people from many backgrounds have a compartment of their memory reserved for The Wizard of Oz.'' — Roger Ebert
"A genuine American classic ... Just as good the fifteenth time as it is the first time." — Leonard Maltin
The Lavender Hill Mob (Charles Crichton, 1951) "It's a minor classic, a charmer." — Pauline Kael
Little Women (George Cukor, 1933) "There are small flaws—a few naïve and cloying scenes, some obvious dramatic contrivances—but it's a lovely, graceful film, and surprisingly faithful to the atmosphere, the Victorian sentiments, and the Victorian strengths of the Louisa May Alcott novel." — Pauline Kael
--
That was it: 45 good suggestions! I hope you enjoyed them and, of course, comment with some of your own!
2009-10-23
Idea Factory quote
Oral exam. They present you with a problem; you have 20 minutes to look at it and try to solve it or at least think up something to say about it, and then you present your solution and/or answer their questions for 20 minutes. To discourage cheating, the 40-minute periods are consecutive, with no time allowed to go from one room to the other. Thus you run from examination room to examination room, to have as much of the 20 minutes of preparation time as possible.
The Idea Factory, Learning to think at MIT
Developing smart Java code
Core Jena interfaces simplified:
Development Methodology
- Define/re-use schema
- Play with example instances, queries etc
- Take a data-centric approach!
- Link key classes of the schema to your Java code (Data Binding)
- Assume schema evolution
- Develop smart, generic code instead of domain specific code
Data model in RDF and RDF Schema
- Data binding to link RDF and Java worlds
- Let the data work with SPARQL
Generic data binding architecture:
New development paradigm based on Linked Data:
- Smart code walks the data graph at run-time
- Very little hard-coding of behavior
- Benefits
-- flexible architecture
-- faster turn-around times
- Challenges
-- learning curve (different from object oriented development)
-- integration with established technologies
Source: Holger Knublauch at JavaOne 2009
I would add that probably "performance" is an additional challenge. Maybe I'll give it a try one of these days...
Development Methodology
- Define/re-use schema
- Play with example instances, queries etc
- Take a data-centric approach!
- Link key classes of the schema to your Java code (Data Binding)
- Assume schema evolution
- Develop smart, generic code instead of domain specific code
Data model in RDF and RDF Schema
- Data binding to link RDF and Java worlds
- Let the data work with SPARQL
Generic data binding architecture:
New development paradigm based on Linked Data:
- Smart code walks the data graph at run-time
- Very little hard-coding of behavior
- Benefits
-- flexible architecture
-- faster turn-around times
- Challenges
-- learning curve (different from object oriented development)
-- integration with established technologies
Source: Holger Knublauch at JavaOne 2009
I would add that probably "performance" is an additional challenge. Maybe I'll give it a try one of these days...
Blackboard systems
Blackboards are a problem solving framework. A blackboard is not used to "search for a solution" but to "assemble knowledge".
A blackboard framework provides:
- reasoning flexibility (backward-chaining, forward-chaining, etc);
- participation of varied sources of knowledge;
- opportunistic contributions;
- incremental solutions;
- interleaving of different forms of reasoning.
Problem Solving:
- divide the problem into loosely coupled subtasks (areas of specialization);
- the solution space is divided in regions (levels) containing partial or intermediate solutions;
- the information in each region is globally accessible on the blackboard, making it a medium of interaction between the knowledge sources;
- the decision to employ a particular knowledge source is made dynamically using the current solution state;
- caveat: the problem partitioning in subproblems makes a great difference in clarity, speed, resources, and the ability to find a solution!
Read more about this subject in Blackboard Systems by Englemore and Morgan.
A blackboard framework provides:
- reasoning flexibility (backward-chaining, forward-chaining, etc);
- participation of varied sources of knowledge;
- opportunistic contributions;
- incremental solutions;
- interleaving of different forms of reasoning.
Problem Solving:
- divide the problem into loosely coupled subtasks (areas of specialization);
- the solution space is divided in regions (levels) containing partial or intermediate solutions;
- the information in each region is globally accessible on the blackboard, making it a medium of interaction between the knowledge sources;
- the decision to employ a particular knowledge source is made dynamically using the current solution state;
- caveat: the problem partitioning in subproblems makes a great difference in clarity, speed, resources, and the ability to find a solution!
Read more about this subject in Blackboard Systems by Englemore and Morgan.
2009-10-21
Day Without Yesterday quote
When I was talking with Lemaître about this subject and feeling stimulated by the grandeur of the picture that he has given us, I told him that I thought cosmology was the branch of science that lies closest to religion. However Lemaître did not agree with me. After thinking it over he suggested psychology as lying closest to religion.Paul Dirac, “The Scientific Work of Georges Lemaître”
The Day Without Yesterday, Lemaître, Einstein and the birth of modern cosmology
2009-10-20
Visualize the invisible
Two very interesting visualization videos.
About RFID:
About other magnetic fields:
About RFID:
Immaterials: the ghost in the field from timo on Vimeo.
About other magnetic fields:
Magnetic Movie from Semiconductor on Vimeo.
2009-10-17
Films picked up by Vatican: Values
Values:
Gandhi (Richard Attenborough, 1982) "Gandhi goes by in a cloud of serenity, and everyone who sees him knuckles under (with the exception of a few misguided fellows, of course). Ben Kingsley ... is impressive; the picture isn't ... Kingsley can't give his role a core, because it has been written completely from the outside. A viewer's reaction: 'I felt as if I had attended the funeral of someone I didn't know.'" — Pauline Kael
"The movie earns comparison with two classic works by David Lean, Lawrence of Arabia and Doctor Zhivago, in its ability to paint a strong human story on a very large canvas." — Roger Ebert
Intolerance (D.W. Griffith, 1919) "D.W. Griffith's epic celebration of the potentialities of the film medium—perhaps the greatest movie ever made and the greatest folly in movie history." — Pauline Kael
Il Decalogo (Krzysztof Kieslowski, 1988) "[Kieslowski] confirmed his status as a major contemporary director with Decalogue(1988), an ambitious series of ten hour-long films funded by Polish TV, telling stories "based" on the Ten Commandments. (InDecalogue 10, for instance, two brothers, an accountant and a punk rocker, both covet the stamp collection they have inherited from their father.) In the same year, Kieslowski expanded segments five and six into two features, A Short Film About a Killing and A Short Film About Love. Partially set, like the rest of the series, on a Warsaw housing estate, A Short Film About a Killing is a grim and powerful tale drawing formal parallels between the act of murder and the workings of the criminal justice system." — from theBaseline biography of Kieslowski
Au Revoir, Les Enfants (Louis Malle, 1987) "Deeply felt film based on an incident from Malle's youth, during WWII, when the headmaster of his Catholic boarding school decided to shield several Jewish children in the midst of Nazi-occupied France." — Leonard Maltin
Dersu Uzala (Akira Kurosawa, 1975) "A poignant, poetic examination of contrasting lives." — Leonard Maltin
The Tree of Wooden Clogs (Ermanno Olmi,1978) "A year in the life of a community of peasants in Northern Italy, just before the turn of the century. Simple, quietly beautiful epic; a work of art." — Leonard Maltin
Open City (Roberto Rossellini, 1945) "Roberto Rossellini burst open the world with this film, made just after the Allies took Rome. The fame of his brutal, melodramatic account of the underground resistance to the Nazi occupation rests on its extraordinary immediacy and its rough, documentary look. . ." — Pauline Kael
Wild Strawberries (Ingmar Bergman, 1957) "Ingmar Bergman's first big popular success in the United States. It's a very uneven film: an eminent physician (Victor Sjöström) looks back over his life, which is tricked up with gothic effects and contrasts ... and with peculiarly unconvincing flashbacks and overexplicit dialogue. It's a very lumpy odyssey, yet who can forget Sjöström's face. . .?" — Pauline Kael
"Still a staple of any serious filmgoer's education." — Leonard Maltin
The Seventh Seal (Ingmar Bergman, 1957) "The images and the omens are medieval, but the modern erotic and psychological insights add tension, and in some cases, as in the burning of the child—witch (Maud Hansson), excruciation. The actors' faces, the aura of magic, the ambiguities, and the riddle at the heart of the film all contribute to its stature." — Pauline Kael
Chariots of Fire (Hugh Hudson, 1981) "The picture is a piece of technological lyricism held together by the glue of simpleminded heroic sentiment; basically, its appeal is in watching a couple of guys win their races." — Pauline Kael
"This is strange. I have no interest in running and am not a partisan in the British class system. Then why should I have been so deeply moved by Chariots of Fire, a British film that has running and class as its subjects?" — Roger Ebert
The Bicycle Thief (Vittorio DeSica, 1950) "This neorealist classic, directed by Vittorio De Sica and written by Cesare Zavattini, is on just about everybody's list of the greatest films. It isn't a movie that warms you, though; it doesn't have the flawed poetry that De Sica's Shoeshine and Miracle in Milan have. It's a more impersonal great film." — Pauline Kael
It's A Wonderful Life (Frank Capra, 1946) "What is remarkable about It's a Wonderful Life is how well it holds up over the years; it's one of those ageless movies, like Casablanca or The Third Man, that improves with age. Some movies, even good ones, should only be seen once. When we know how they turn out, they've surrendered their mystery and appeal. Other movies can be viewed an indefinite number of times. Like great music, they improve with familiarity. It's a Wonderful Life falls in the second category. ." — Roger Ebert
"Frank Capra's most relentless lump-in-the-throat movie ... This picture developed a considerable—if bewildering—reputation, based largely on television viewing, about three decades later." — Pauline Kael
Schindler's List (Steven Spielberg, 1993) "In this movie, the best he has ever made, Spielberg treats the fact of the Holocaust and the miracle of Schindler's feat without the easy formulas of fiction. The movie is 184 minutes long, and like all great movies, it seems too short." — Roger Ebert
On the Waterfront (Elia Kazan, 1954) "The director, Elia Kazan, and the writer, Budd Schulberg, start out to expose racketeering in the waterfront unions, and wind up trying to make the melodrama transcend itself. They fail, but the production took eight Academy Awards anyway, and most of them were deserved. It is one of the most powerful American movies of the 50s, and few movies caused so much talk, excitement, and dissension—largely because of Marlon Brando's performance as the inarticulate, instinctively alienated bum, Terry Malloy." — Pauline Kael
The Burmese Harp (Kon Ichikawa, 1956) "Extraordinary anti-war drama is affecting and memorable if a bit overlong." — Leonard Maltin
--
Next week: Art
Gandhi (Richard Attenborough, 1982) "Gandhi goes by in a cloud of serenity, and everyone who sees him knuckles under (with the exception of a few misguided fellows, of course). Ben Kingsley ... is impressive; the picture isn't ... Kingsley can't give his role a core, because it has been written completely from the outside. A viewer's reaction: 'I felt as if I had attended the funeral of someone I didn't know.'" — Pauline Kael
"The movie earns comparison with two classic works by David Lean, Lawrence of Arabia and Doctor Zhivago, in its ability to paint a strong human story on a very large canvas." — Roger Ebert
Intolerance (D.W. Griffith, 1919) "D.W. Griffith's epic celebration of the potentialities of the film medium—perhaps the greatest movie ever made and the greatest folly in movie history." — Pauline Kael
Il Decalogo (Krzysztof Kieslowski, 1988) "[Kieslowski] confirmed his status as a major contemporary director with Decalogue(1988), an ambitious series of ten hour-long films funded by Polish TV, telling stories "based" on the Ten Commandments. (InDecalogue 10, for instance, two brothers, an accountant and a punk rocker, both covet the stamp collection they have inherited from their father.) In the same year, Kieslowski expanded segments five and six into two features, A Short Film About a Killing and A Short Film About Love. Partially set, like the rest of the series, on a Warsaw housing estate, A Short Film About a Killing is a grim and powerful tale drawing formal parallels between the act of murder and the workings of the criminal justice system." — from theBaseline biography of Kieslowski
Au Revoir, Les Enfants (Louis Malle, 1987) "Deeply felt film based on an incident from Malle's youth, during WWII, when the headmaster of his Catholic boarding school decided to shield several Jewish children in the midst of Nazi-occupied France." — Leonard Maltin
Dersu Uzala (Akira Kurosawa, 1975) "A poignant, poetic examination of contrasting lives." — Leonard Maltin
The Tree of Wooden Clogs (Ermanno Olmi,1978) "A year in the life of a community of peasants in Northern Italy, just before the turn of the century. Simple, quietly beautiful epic; a work of art." — Leonard Maltin
Open City (Roberto Rossellini, 1945) "Roberto Rossellini burst open the world with this film, made just after the Allies took Rome. The fame of his brutal, melodramatic account of the underground resistance to the Nazi occupation rests on its extraordinary immediacy and its rough, documentary look. . ." — Pauline Kael
Wild Strawberries (Ingmar Bergman, 1957) "Ingmar Bergman's first big popular success in the United States. It's a very uneven film: an eminent physician (Victor Sjöström) looks back over his life, which is tricked up with gothic effects and contrasts ... and with peculiarly unconvincing flashbacks and overexplicit dialogue. It's a very lumpy odyssey, yet who can forget Sjöström's face. . .?" — Pauline Kael
"Still a staple of any serious filmgoer's education." — Leonard Maltin
The Seventh Seal (Ingmar Bergman, 1957) "The images and the omens are medieval, but the modern erotic and psychological insights add tension, and in some cases, as in the burning of the child—witch (Maud Hansson), excruciation. The actors' faces, the aura of magic, the ambiguities, and the riddle at the heart of the film all contribute to its stature." — Pauline Kael
Chariots of Fire (Hugh Hudson, 1981) "The picture is a piece of technological lyricism held together by the glue of simpleminded heroic sentiment; basically, its appeal is in watching a couple of guys win their races." — Pauline Kael
"This is strange. I have no interest in running and am not a partisan in the British class system. Then why should I have been so deeply moved by Chariots of Fire, a British film that has running and class as its subjects?" — Roger Ebert
The Bicycle Thief (Vittorio DeSica, 1950) "This neorealist classic, directed by Vittorio De Sica and written by Cesare Zavattini, is on just about everybody's list of the greatest films. It isn't a movie that warms you, though; it doesn't have the flawed poetry that De Sica's Shoeshine and Miracle in Milan have. It's a more impersonal great film." — Pauline Kael
It's A Wonderful Life (Frank Capra, 1946) "What is remarkable about It's a Wonderful Life is how well it holds up over the years; it's one of those ageless movies, like Casablanca or The Third Man, that improves with age. Some movies, even good ones, should only be seen once. When we know how they turn out, they've surrendered their mystery and appeal. Other movies can be viewed an indefinite number of times. Like great music, they improve with familiarity. It's a Wonderful Life falls in the second category. ." — Roger Ebert
"Frank Capra's most relentless lump-in-the-throat movie ... This picture developed a considerable—if bewildering—reputation, based largely on television viewing, about three decades later." — Pauline Kael
Schindler's List (Steven Spielberg, 1993) "In this movie, the best he has ever made, Spielberg treats the fact of the Holocaust and the miracle of Schindler's feat without the easy formulas of fiction. The movie is 184 minutes long, and like all great movies, it seems too short." — Roger Ebert
On the Waterfront (Elia Kazan, 1954) "The director, Elia Kazan, and the writer, Budd Schulberg, start out to expose racketeering in the waterfront unions, and wind up trying to make the melodrama transcend itself. They fail, but the production took eight Academy Awards anyway, and most of them were deserved. It is one of the most powerful American movies of the 50s, and few movies caused so much talk, excitement, and dissension—largely because of Marlon Brando's performance as the inarticulate, instinctively alienated bum, Terry Malloy." — Pauline Kael
The Burmese Harp (Kon Ichikawa, 1956) "Extraordinary anti-war drama is affecting and memorable if a bit overlong." — Leonard Maltin
--
Next week: Art
2009-10-16
hell(o) world
As part of the effort to upgrade the STEP Framework to Java 6 and Tomcat 6, I had a long fight with a software bug. It cost me almost a week's worth of work! Unbelievable!
The error message was "WebServiceException class X do not have a property of the name {Y}Z". The JAX-WS Web Service would work when I didn't have any SOAP handlers configured but would happen whenever I tried to add them back.
I tried changing so many things, one at a time of course, to try and find out the cause for the bug. I went over JAX-WS and JAX-B's source code. But the bug was very elusive.
Thanks to proffy I finally figured it out.
Because of a JAX-WS bug, the generated classes must be compiled by wsimport. If they are compiled later by javac it doesn't work!
The handlers configurations are generated in the build folder. The sources are also generated in the build folder, for programmer reference.
See also: bug report, image credits.
The error message was "WebServiceException class X do not have a property of the name {Y}Z". The JAX-WS Web Service would work when I didn't have any SOAP handlers configured but would happen whenever I tried to add them back.
I tried changing so many things, one at a time of course, to try and find out the cause for the bug. I went over JAX-WS and JAX-B's source code. But the bug was very elusive.
Thanks to proffy I finally figured it out.
Because of a JAX-WS bug, the generated classes must be compiled by wsimport. If they are compiled later by javac it doesn't work!
The handlers configurations are generated in the build folder. The sources are also generated in the build folder, for programmer reference.
See also: bug report, image credits.
2009-10-14
Future directions for Java Web Services
I have been a Java Web Services developer for 8 years now, and I've mostly worked with Sun's reference implementation: JAX-WS.
Recently I have been trying to upgrade to the latest version blunded with Java SE 6 and I'm having several difficulties that appear to be bugs. I'm not talking about anything far fetched... For instance, I'm having issues with using simple SOAP handlers that worked perfectly in the previous versions. Also the jax-b, jax-ws, metro java.net sites appear to be somewhat "abandoned".
So given this state of affairs, I'm considering switching to another Java Web Services implementation. This is where you can help!
If you were to choose an implementation for a Java Web Services project today and for the next 3 years, which would you pick and why?
Feel free to make any other suggestions or comments. Thanks in advance!
Recently I have been trying to upgrade to the latest version blunded with Java SE 6 and I'm having several difficulties that appear to be bugs. I'm not talking about anything far fetched... For instance, I'm having issues with using simple SOAP handlers that worked perfectly in the previous versions. Also the jax-b, jax-ws, metro java.net sites appear to be somewhat "abandoned".
So given this state of affairs, I'm considering switching to another Java Web Services implementation. This is where you can help!
If you were to choose an implementation for a Java Web Services project today and for the next 3 years, which would you pick and why?
Feel free to make any other suggestions or comments. Thanks in advance!
Day Without Yesterday quote
Lemaître’s insights were in fact key in almost all the important milestones of early modern cosmology, from the expanding universe, to the cosmological constant, to black holes. He was first to see how the Einstein and de Sitter models were but two limited cases of a larger body of expanding universe models; he was the first to see that such models had to evolve from a super-dense state; and perhaps most importantly – from the very beginning – he was the first to tie the predictions of relativity about cosmology to actual astronomical observations.
The Day Without Yesterday, Lemaître, Einstein and the birth of modern cosmology
2009-10-12
2009-10-11
2009-10-10
Films picked up by Vatican: Religion
"(...) the Vatican has decided to take a more upbeat approach and give a Big Thumbs Up to 45 movies it feels express Catholic tastes in three categories: Religion, Values, and Art. The selections, made by a Vatican committee in commemoration of the centenary of motion pictures in 1996, are films that The Church feels exemplify what's best about the medium."
Religion:
Andrei Roublev (Andrei Tarkovsky, 1966) "Brilliantly devised and directed account of the famous 15th century icon painter, focusing on an age—old conflict: should an artist participate in the political and social upheavals of the time, or should he simply record history with his brush?" — Leonard Maltin
The Mission (Roland Joffe, 1986) "You'd like to know why so many talented people went to such incredible lengths to make a difficult and beautiful movie—without any of them, on the basis of the available evidence, having the slightest notion of what the movie was about." — Roger Ebert
The Passion of Joan of Arc (Carl Theodor Dreyer, 1928) "No other film has so subtly linked eroticism with religious persecution. Falconetti's Joan may be the finest performance ever recorded on film." — Pauline Kael
The Gospel According to St. Matthew (Pier Paolo Pasolini, 1966) "Pasolini's interpretation features the rocky settings of Southern Italy, an eclectic score, and a rigid Jesus who demands obedience." — Pauline Kael
Therese (Alain Cavalier, 1986) "Therese is not like any other biographical film of a saint—or of anyone else. It makes a bold attempt to penetrate to the mystery of Therese's sainthood, and yet it isn't propaganda for the church and it doesn't necessarily even approve of her choice of a vocation." — Roger Ebert
Ordet (Carl Theodor Dreyer, 1955) "Arguably Dreyer's greatest film, but certainly the movies' final word on the struggle between conventional Christianity and more personalized religious faith. Truly awe—inspiring. . ." — Leonard Maltin
The Sacrifice (Tarkovsky, 1986) "Slow, overly intense, but beautifully filmed (by Sven Nykvist) examination of the need for, and lack of, spirituality in modern society." — Leonard Maltin
Francis (not the Talking Mule picture)
Ben-Hur (William Wyler, 1959) "Movie moguls have always had a real affinity for the grandiosity of the old Roman Empire ... Lew Wallace's hectic potboiler-classic has everything—even leprosy." — Pauline Kael
Babette's Feast (Gabriel Axel, 1987) "Subtle, funny and deeply felt, with several wonderful surprises: an instant masterpiece. . ."— Leonard Maltin
Nazarin (Luis Bunuel, 1958) "The hero is a gentle Mexican priest—a Candide who is robbed and cheated—in this simple, masterly, ambiguous film by Luis Buñuel which is (perhaps in spite of his intention) his most tender." — Pauline Kael
Monsieur Vincent (Jean Anouilh, 1947) "Pierre Fresnay's performance as the desperately compassionate Vincent de Paul gives extraordinary feeling to Jean Anouilh's sensitive, lucid scenario." — Pauline Kael
A Man For All Seasons (Fred Zinnemann, 1966) "The director, Fred Zinnemann, places himself at the service of Robert Bolt's play about the moral tug of war between Sir Thomas More (Paul Scofield) and Henry VIII (Robert Shaw), and the results are tasteful and moderately enjoyable." — Pauline Kael
La Passion Pathe
Flowers of St. Francis (Roberto Rossellini, 1950)
--
Next week: Values
Thanks to Joana for "digging" these suggestions out of her mailbox!
Religion:
Andrei Roublev (Andrei Tarkovsky, 1966) "Brilliantly devised and directed account of the famous 15th century icon painter, focusing on an age—old conflict: should an artist participate in the political and social upheavals of the time, or should he simply record history with his brush?" — Leonard Maltin
The Mission (Roland Joffe, 1986) "You'd like to know why so many talented people went to such incredible lengths to make a difficult and beautiful movie—without any of them, on the basis of the available evidence, having the slightest notion of what the movie was about." — Roger Ebert
The Passion of Joan of Arc (Carl Theodor Dreyer, 1928) "No other film has so subtly linked eroticism with religious persecution. Falconetti's Joan may be the finest performance ever recorded on film." — Pauline Kael
The Gospel According to St. Matthew (Pier Paolo Pasolini, 1966) "Pasolini's interpretation features the rocky settings of Southern Italy, an eclectic score, and a rigid Jesus who demands obedience." — Pauline Kael
Therese (Alain Cavalier, 1986) "Therese is not like any other biographical film of a saint—or of anyone else. It makes a bold attempt to penetrate to the mystery of Therese's sainthood, and yet it isn't propaganda for the church and it doesn't necessarily even approve of her choice of a vocation." — Roger Ebert
Ordet (Carl Theodor Dreyer, 1955) "Arguably Dreyer's greatest film, but certainly the movies' final word on the struggle between conventional Christianity and more personalized religious faith. Truly awe—inspiring. . ." — Leonard Maltin
The Sacrifice (Tarkovsky, 1986) "Slow, overly intense, but beautifully filmed (by Sven Nykvist) examination of the need for, and lack of, spirituality in modern society." — Leonard Maltin
Francis (not the Talking Mule picture)
Ben-Hur (William Wyler, 1959) "Movie moguls have always had a real affinity for the grandiosity of the old Roman Empire ... Lew Wallace's hectic potboiler-classic has everything—even leprosy." — Pauline Kael
Babette's Feast (Gabriel Axel, 1987) "Subtle, funny and deeply felt, with several wonderful surprises: an instant masterpiece. . ."— Leonard Maltin
Nazarin (Luis Bunuel, 1958) "The hero is a gentle Mexican priest—a Candide who is robbed and cheated—in this simple, masterly, ambiguous film by Luis Buñuel which is (perhaps in spite of his intention) his most tender." — Pauline Kael
Monsieur Vincent (Jean Anouilh, 1947) "Pierre Fresnay's performance as the desperately compassionate Vincent de Paul gives extraordinary feeling to Jean Anouilh's sensitive, lucid scenario." — Pauline Kael
A Man For All Seasons (Fred Zinnemann, 1966) "The director, Fred Zinnemann, places himself at the service of Robert Bolt's play about the moral tug of war between Sir Thomas More (Paul Scofield) and Henry VIII (Robert Shaw), and the results are tasteful and moderately enjoyable." — Pauline Kael
La Passion Pathe
Flowers of St. Francis (Roberto Rossellini, 1950)
--
Next week: Values
Thanks to Joana for "digging" these suggestions out of her mailbox!
2009-10-09
Freedom Writers
Freedom Writers
Miep Gies: But even an ordinary secretary or a housewife or a teenager can, within their own small ways, turn on a small light in a dark room.
Idea Factory quote
The first definition of thesis is a proposition advanced and maintained by argument. If there is no proposition there is no thesis. If there is no thesis there is no degree.
The Idea Factory, Learning to think at MIT
2009-10-08
2009-10-07
Inboxing
I'm not the first to come up with it (see urban dictionary) but I'd like to propose the word Inboxing.
An inbox is a container in which all the papers to be dealt with are put. Or, figuratively, it is the aggregate of items that demand one's attention or effort.
Boxing, of course, is a combat sport where two participants, generally of similar weight, fight each other with their fists.
Inboxing is the fight you have to go through every day to clean all the items that find their way to your inbox: emails, chats, feeds, papers, etc.
It's worth fighting to claim back your time to think and be creative!
Good luck! Unlike boxing, in inboxing the two participants don't have similar weight :-)
An inbox is a container in which all the papers to be dealt with are put. Or, figuratively, it is the aggregate of items that demand one's attention or effort.
Boxing, of course, is a combat sport where two participants, generally of similar weight, fight each other with their fists.
Inboxing is the fight you have to go through every day to clean all the items that find their way to your inbox: emails, chats, feeds, papers, etc.
It's worth fighting to claim back your time to think and be creative!
Good luck! Unlike boxing, in inboxing the two participants don't have similar weight :-)
Day Without Yesterday quote
Although I didn’t know it at the time, the exponentially expanding space that I discovered was hardly new – it was in fact one of the earliest known solutions to the equations of general relativity. I had rediscovered the equations of de Sitter’s cosmology of 1917, written in a form that was introduced by Georges Lemaître in 1925 as part of his Ph.D. thesis at MIT.Alan Guth, The Inflationary Universe
The Day Without Yesterday, Lemaître, Einstein and the birth of modern cosmology
2009-10-06
Practical advice about Distributed Systems
Distributed Systems generic approach:
- Develop "entity"
-- Define the Unit-of-Work (UOW) it supports
- Search for "entity"
-- Agree "entity" offers the desired capability or UOW
- Request "entity" to perform UOW
-- Create a network-transferable message
-- Send the message
-- Maybe try to make the remote interaction appear local
-- Maybe do some "enterprise" (Security, transactions, replication etc.) work as well
The same requirements are present throughout the stack:
- Uniform interface allows for generic infrastructural support
-- Caching, extremely loose coupling
-- Can push more requirements on to the "developer"
-- Requires more from external contract meta-data
- Specific interface allows for more limited generic support
-- Targeted caching, application semantics
-- Impacts less on the "developer" but may cost in terms of flexibility
Different approaches to distribution - there is no global panacea:
- Event Driven Architectures (Pub/Sub)
- Service Oriented Architectures
- Resource Oriented Architectures
- Message Oriented Architectures (MOM, Pub/Sub)
- Tuple Spaces (E.g., Linda, Jini)
- RPC based
- Group communication based (Reliable or unreliable)
Source: Mark Little at JavaOne 2009
- Develop "entity"
-- Define the Unit-of-Work (UOW) it supports
- Search for "entity"
-- Agree "entity" offers the desired capability or UOW
- Request "entity" to perform UOW
-- Create a network-transferable message
-- Send the message
-- Maybe try to make the remote interaction appear local
-- Maybe do some "enterprise" (Security, transactions, replication etc.) work as well
The same requirements are present throughout the stack:
- Uniform interface allows for generic infrastructural support
-- Caching, extremely loose coupling
-- Can push more requirements on to the "developer"
-- Requires more from external contract meta-data
- Specific interface allows for more limited generic support
-- Targeted caching, application semantics
-- Impacts less on the "developer" but may cost in terms of flexibility
Different approaches to distribution - there is no global panacea:
- Event Driven Architectures (Pub/Sub)
- Service Oriented Architectures
- Resource Oriented Architectures
- Message Oriented Architectures (MOM, Pub/Sub)
- Tuple Spaces (E.g., Linda, Jini)
- RPC based
- Group communication based (Reliable or unreliable)
Source: Mark Little at JavaOne 2009
2009-10-05
Multiple iTunes libraries
You can use multiple music libraries in iTunes (and iPhoto). The choice is made at startup: just hold down the shift/option key when you click the iTunes icon.
In Windows the default music library is stored in C:\Users\You\Music\iTunes, in case you want to find it again.
In Windows the default music library is stored in C:\Users\You\Music\iTunes, in case you want to find it again.
2009-10-04
2009-10-02
A esperança está onde menos se espera
A esperança está onde menos se espera
It's always good to watch a Portuguese movie. Too bad about Virgílio Castelo's overacting and the exagerated reliance on cliches to convey the movie's message. Otherwise an interesting movie dealing with important issues in Portuguese society.
/ This post is bilingual: English (U.S.) and Portuguese (Portugal) /
É sempre bom assistir a um filme Português. Só é pena o excesso de actuação de Virgílio Castelo e a utilização exagerada de clichês para passar a mensagem do filme. De resto, um filme interessante que trata alguns temas importantes da sociedade portuguesa.
http://www.mgnfilmes.pt/aesperanca/
It's always good to watch a Portuguese movie. Too bad about Virgílio Castelo's overacting and the exagerated reliance on cliches to convey the movie's message. Otherwise an interesting movie dealing with important issues in Portuguese society.
/ This post is bilingual: English (U.S.) and Portuguese (Portugal) /
É sempre bom assistir a um filme Português. Só é pena o excesso de actuação de Virgílio Castelo e a utilização exagerada de clichês para passar a mensagem do filme. De resto, um filme interessante que trata alguns temas importantes da sociedade portuguesa.
http://www.mgnfilmes.pt/aesperanca/
Idea Factory quote
All the graphs looked the same, sitting side by side.
There has to be a pattern...
The Idea Factory, Learning to think at MIT
2009-10-01
Novidades nos Doutoramentos em Portugal / News about PhDs in Portugal
Por outro lado, importa, ainda, introduzir no sistema de ensino superior nacional a possibilidade de realização do doutoramento com base na compilação de um conjunto de publicações científicas anteriores, publicadas em revistas com comités de selecção de reconhecido mérito, prática hoje internacionalmente utilizada.
Neste sentido, e em condições de exigência equivalentes à da modalidade de doutoramento com base numa tese, introduz-se a possibilidade de obtenção do grau de doutor com base no reconhecimento e análise de obras, e com base em trabalhos científicos publicados.
/ This post is bilingual: Portuguese (Portugal) and English (U.S.) /
From now on, a Doctoral degree in Portugal can be obtained with a collection of published articles instead of the mandatory dissertation.
Setting up a collaboration server for a small team
I have recently setup a collaboration server for a small research team.
I'm posting a short guide describing all the steps.
---
The operating system is Microsoft Windows. The base installation was complemented with a set of free tools: Notepad++, 7-Zip, SysInternals suite.
Every time a service configuration is significantly changed, it should be stopped and restarted to load the new configuration. These restarts are not explicitly mentioned in the following steps.
... is used to mark placeholders for values that are either case-specific or sensitive, like passwords.
PART 1 - XAMPP
1.1 - Download XAMPP for Windows
1.2 - Install XAMPP to C:\
1.3 - Use the XAMPP console to manage the services and access the XAMPP shell
PART 2 - SVN
2.1 - Download SVN for Windows
Double check that you are getting a version compatible with the Apache bundled in XAMPP.
2.2 - Install SVN
2.3 - Copy mod_dav_svn.so and mod_authz_svn.so from SVN binaries folder to C:\xampp\apache\modules
2.4 - Edit C:\xampp\apache\conf\httpd.conf and add:
# svn repository access (note: confirm mod_dav.so and mod_dav_fs.so are loaded above)
LoadModule dav_svn_module modules/mod_dav_svn.so
LoadModule authz_svn_module modules/mod_authz_svn.so
(...)
# svn configuration
Include c:/etc/subversion.conf
2.5 - Create C:\svn and C:\svn\repo folders
2.6 - Create a project repository
shell> svnadmin create C:\svn\repo
2.7 - Create empty configuration files:
C:\svn\svn-auth-file
C:\svn\svn-acl
C:\svn\subversion.conf
2.8 - Create users
XAMPP shell> htpasswd -cm C:\svn\svn-auth-file first-user...
XAMPP shell> htpasswd -m C:\etc\svn-auth-file next-user...
2.9 - Create ACL: C:\svn\svn-acl
[groups]
groupname = user1, user2
# group has a read/write access to project repository
# all subdirectories
# all others have read access only
[svn:/]
@groupname = rw
* = r
2.10 - Create subversion configuration: C:\svn\subversion.conf
(/svn is the path used for the repository web address)
DAV svn
SVNPath C:/svn/repo
AuthType Basic
AuthName "Subversion repository"
AuthUserFile c:/svn/svn-auth-file
Require valid-user
AuthzSVNAccessFile c:/svn/svn-acl
2.11 - Create standard repository layout and import it to repository
shell> cd temp
shell> mkdir layout
shell> cd layout
shell> mkdir trunk
shell> mkdir branches
shell> mkdir tags
shell> svn import . https://.../svn -m "Initial repository layout"
References:
http://svn.haxx.se/users/archive-2005-05/0741.shtml
http://svn.spears.at/
PART 3 - DokuWiki
3.1 - Download DokuWiki
3.2 - Unzip and untar. Copy the contents of the main folder to C:\xampp\htdocs\dokuwiki
3.3 - Access the initial installation script
http://.../dokuwiki/install.php
Wiki Name - title
Enable ACL
Superuser - admin
Full Name
E-Mail
Password
Once Again
Initial ACL policy - closed wiki
3.4 - Login using admin user and use administrative interface to create users
http://.../dokuwiki/
Data files location:
C:\xampp\htdocs\dokuwiki\data\
References:
http://www.dokuwiki.org/Install
PART 4 - StatusNet
4.1 - Download StatusNet
4.2 - Unzip and untar. Copy main folder contents to C:\xampp\htdocs\statusnet
4.3 - Create MySQL database, create user and password, grant access rights
XAMPP shell> mysql -u root
CREATE DATABASE statusnet;
GRANT ALL on statusnet.*
TO 'statusnetuser'@'localhost'
IDENTIFIED BY '...';
4.4 - Edit database creation script: C:\xampp\htdocs\statusnet\db\statusnet.sql
Add the following line to the top of the file:
USE statusnet;
4.5 - Execute database creation script.
XAMPP shell> mysql -u root < C:\xampp\htdocs\statusnet\db\statusnet.sql
4.6 - Create and edit configuration file: C:\xampp\htdocs\statusnet\config.php
XAMPP shell> copy C:\xampp\htdocs\statusnet\config.php.sample C:\xampp\htdocs\statusnet\config.php
Write/uncomment following lines in :
$config['site']['name'] = 'My status net';
$config['site']['server'] = 'my.server.address.net';
$config['site']['openidonly'] = false;
$config['site']['private'] = true;
$config['db']['database'] = 'mysql://statusnetuser:...@localhost/statusnet';
$config['db']['debug'] = 0;
$config['xmpp']['enabled'] = false;
$config['openid']['enabled'] = false;
$config['invite']['enabled'] = false;
$config['site']['timezone'] = 'Europe/London';
$config['site']['language'] = 'en_GB';
$config['memcached']['enabled'] = false;
$config['emailpost']['enabled'] = false;
$config['sms']['enabled'] = false;
$config['twitter']['enabled'] = false;
$config['twitterbridge']['enabled'] = false;
$config['site']['ssl'] = 'sometimes';
4.7 - Rename undesired locale folders:
C:\xampp\htdocs\statusnet\locale\pt
to _pt
C:\xampp\htdocs\statusnet\locale\pt_BR
to _pt_BR
4.8 - Access site, register all users, one at a time
4.9 - Edit configuration file to close registrations: C:\xampp\htdocs\statusnet\config.php:
$config['site']['closed'] = true;
Known bugs:
- logout doesn't work
- Post attachments don't work
- HTTPS always option doesn't work properly - some links are generated with HTTP anyway - using HTTPS sometimes to, at least, protect user and password
Missing features:
- no data migration support
References:
C:\xampp\htdocs\statusnet\README
http://status.net/wiki/Installation
PART 5 - Security
5.1 - Change MySQL password
http://.../security/xamppsecurity.php
new password
repeat ...
phpMyAdmin authentication: cookie
Set random...: yes
Click 'Password changing'
5.2 - Change XAMPP directory protection (after this step, the user and password will be required to access XAMPP)
http://.../security/xamppsecurity.php
user
password
5.3 - Generate a new self-signed certificate and replace the default
XAMPP shell>makecert
# makecert
Loading 'screen' into random state - done
Generating a 1024 bit RSA private key
..++++++
....++++++
writing new private key to 'privkey.pem'
Enter PEM pass phrase:
Verifying - Enter PEM pass phrase:
You are about to be asked to enter information that will be incorporated into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [AU]:
State or Province Name (full name) [Some-State]:
Locality Name (eg, city) []:
Organization Name (eg, company) [Internet Widgits Pty Ltd]:
Organizational Unit Name (eg, section) []:
Common Name (eg, YOUR name) []:...
Email Address []:
Please enter the following 'extra' attributes
to be sent with your certificate request
A challenge password []:
An optional company name []:
Enter pass phrase for privkey.pem:
writing RSA key
Loading 'screen' into random state - done
Signature ok
Getting Private key
-----
Das Zertifikat wurde erstellt.
The certificate was provided.
5.4 - Configure FileZilla security
FileZilla Server interface, Edit settings, SSL/TLS Settings
Enable FTP over SSL/TLS support (FTPS)
Use same private key and certificate as Apache
Private key: C:\xampp\apache\conf\ssl.key\server.key
Certificate: C:\xampp\apache\conf\ssl.crt\server.crt
Allow explicit FTP over TLS
Disallow plain unencrypted FTP
5.5 - Remove default index
Rename C:\xampp\htdocs\index.php
Edit C:\xampp\htdocs\index.html
5.6 - Configure Firewall
Go to: Control Panel - Windows Firewall | Exceptions
Add rules
Program: c:\xampp\FileZilla\FilleZilla Server.exe
Ports: 80 Apache HTTP, 443 Apache HTTPS
References:
http://www.apachefriends.org/en/xampp-windows.html#1221
http://robsnotebook.com/xampp-ssl-encrypt-passwords
---
And that's it! :-)
You know should have a collaboration server up and running.
Thanks to all the authors of the used open-source projects and references. Keep up the good work!
The most unstable component is StatusNet. I'm looking forward to a (stable) version 1.0.
I'm posting a short guide describing all the steps.
---
The operating system is Microsoft Windows. The base installation was complemented with a set of free tools: Notepad++, 7-Zip, SysInternals suite.
Every time a service configuration is significantly changed, it should be stopped and restarted to load the new configuration. These restarts are not explicitly mentioned in the following steps.
... is used to mark placeholders for values that are either case-specific or sensitive, like passwords.
PART 1 - XAMPP
1.1 - Download XAMPP for Windows
1.2 - Install XAMPP to C:\
1.3 - Use the XAMPP console to manage the services and access the XAMPP shell
PART 2 - SVN
2.1 - Download SVN for Windows
Double check that you are getting a version compatible with the Apache bundled in XAMPP.
2.2 - Install SVN
2.3 - Copy mod_dav_svn.so and mod_authz_svn.so from SVN binaries folder to C:\xampp\apache\modules
2.4 - Edit C:\xampp\apache\conf\httpd.conf and add:
# svn repository access (note: confirm mod_dav.so and mod_dav_fs.so are loaded above)
LoadModule dav_svn_module modules/mod_dav_svn.so
LoadModule authz_svn_module modules/mod_authz_svn.so
(...)
# svn configuration
Include c:/etc/subversion.conf
2.5 - Create C:\svn and C:\svn\repo folders
2.6 - Create a project repository
shell> svnadmin create C:\svn\repo
2.7 - Create empty configuration files:
C:\svn\svn-auth-file
C:\svn\svn-acl
C:\svn\subversion.conf
2.8 - Create users
XAMPP shell> htpasswd -cm C:\svn\svn-auth-file first-user...
XAMPP shell> htpasswd -m C:\etc\svn-auth-file next-user...
2.9 - Create ACL: C:\svn\svn-acl
[groups]
groupname = user1, user2
# group has a read/write access to project repository
# all subdirectories
# all others have read access only
[svn:/]
@groupname = rw
* = r
2.10 - Create subversion configuration: C:\svn\subversion.conf
(/svn is the path used for the repository web address)
DAV svn
SVNPath C:/svn/repo
AuthType Basic
AuthName "Subversion repository"
AuthUserFile c:/svn/svn-auth-file
Require valid-user
AuthzSVNAccessFile c:/svn/svn-acl
2.11 - Create standard repository layout and import it to repository
shell> cd temp
shell> mkdir layout
shell> cd layout
shell> mkdir trunk
shell> mkdir branches
shell> mkdir tags
shell> svn import . https://.../svn -m "Initial repository layout"
References:
http://svn.haxx.se/users/archive-2005-05/0741.shtml
http://svn.spears.at/
PART 3 - DokuWiki
3.1 - Download DokuWiki
3.2 - Unzip and untar. Copy the contents of the main folder to C:\xampp\htdocs\dokuwiki
3.3 - Access the initial installation script
http://.../dokuwiki/install.php
Wiki Name - title
Enable ACL
Superuser - admin
Full Name
Password
Once Again
Initial ACL policy - closed wiki
3.4 - Login using admin user and use administrative interface to create users
http://.../dokuwiki/
Data files location:
C:\xampp\htdocs\dokuwiki\data\
References:
http://www.dokuwiki.org/Install
PART 4 - StatusNet
4.1 - Download StatusNet
4.2 - Unzip and untar. Copy main folder contents to C:\xampp\htdocs\statusnet
4.3 - Create MySQL database, create user and password, grant access rights
XAMPP shell> mysql -u root
CREATE DATABASE statusnet;
GRANT ALL on statusnet.*
TO 'statusnetuser'@'localhost'
IDENTIFIED BY '...';
4.4 - Edit database creation script: C:\xampp\htdocs\statusnet\db\statusnet.sql
Add the following line to the top of the file:
USE statusnet;
4.5 - Execute database creation script.
XAMPP shell> mysql -u root < C:\xampp\htdocs\statusnet\db\statusnet.sql
4.6 - Create and edit configuration file: C:\xampp\htdocs\statusnet\config.php
XAMPP shell> copy C:\xampp\htdocs\statusnet\config.php.sample C:\xampp\htdocs\statusnet\config.php
Write/uncomment following lines in :
$config['site']['name'] = 'My status net';
$config['site']['server'] = 'my.server.address.net';
$config['site']['openidonly'] = false;
$config['site']['private'] = true;
$config['db']['database'] = 'mysql://statusnetuser:...@localhost/statusnet';
$config['db']['debug'] = 0;
$config['xmpp']['enabled'] = false;
$config['openid']['enabled'] = false;
$config['invite']['enabled'] = false;
$config['site']['timezone'] = 'Europe/London';
$config['site']['language'] = 'en_GB';
$config['memcached']['enabled'] = false;
$config['emailpost']['enabled'] = false;
$config['sms']['enabled'] = false;
$config['twitter']['enabled'] = false;
$config['twitterbridge']['enabled'] = false;
$config['site']['ssl'] = 'sometimes';
4.7 - Rename undesired locale folders:
C:\xampp\htdocs\statusnet\locale\pt
to _pt
C:\xampp\htdocs\statusnet\locale\pt_BR
to _pt_BR
4.8 - Access site, register all users, one at a time
4.9 - Edit configuration file to close registrations: C:\xampp\htdocs\statusnet\config.php:
$config['site']['closed'] = true;
Known bugs:
- logout doesn't work
- Post attachments don't work
- HTTPS always option doesn't work properly - some links are generated with HTTP anyway - using HTTPS sometimes to, at least, protect user and password
Missing features:
- no data migration support
References:
C:\xampp\htdocs\statusnet\README
http://status.net/wiki/Installation
PART 5 - Security
5.1 - Change MySQL password
http://.../security/xamppsecurity.php
new password
repeat ...
phpMyAdmin authentication: cookie
Set random...: yes
Click 'Password changing'
5.2 - Change XAMPP directory protection (after this step, the user and password will be required to access XAMPP)
http://.../security/xamppsecurity.php
user
password
5.3 - Generate a new self-signed certificate and replace the default
XAMPP shell>makecert
# makecert
Loading 'screen' into random state - done
Generating a 1024 bit RSA private key
..++++++
....++++++
writing new private key to 'privkey.pem'
Enter PEM pass phrase:
Verifying - Enter PEM pass phrase:
You are about to be asked to enter information that will be incorporated into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [AU]:
State or Province Name (full name) [Some-State]:
Locality Name (eg, city) []:
Organization Name (eg, company) [Internet Widgits Pty Ltd]:
Organizational Unit Name (eg, section) []:
Common Name (eg, YOUR name) []:...
Email Address []:
Please enter the following 'extra' attributes
to be sent with your certificate request
A challenge password []:
An optional company name []:
Enter pass phrase for privkey.pem:
writing RSA key
Loading 'screen' into random state - done
Signature ok
Getting Private key
-----
Das Zertifikat wurde erstellt.
The certificate was provided.
5.4 - Configure FileZilla security
FileZilla Server interface, Edit settings, SSL/TLS Settings
Enable FTP over SSL/TLS support (FTPS)
Use same private key and certificate as Apache
Private key: C:\xampp\apache\conf\ssl.key\server.key
Certificate: C:\xampp\apache\conf\ssl.crt\server.crt
Allow explicit FTP over TLS
Disallow plain unencrypted FTP
5.5 - Remove default index
Rename C:\xampp\htdocs\index.php
Edit C:\xampp\htdocs\index.html
5.6 - Configure Firewall
Go to: Control Panel - Windows Firewall | Exceptions
Add rules
Program: c:\xampp\FileZilla\FilleZilla Server.exe
Ports: 80 Apache HTTP, 443 Apache HTTPS
References:
http://www.apachefriends.org/en/xampp-windows.html#1221
http://robsnotebook.com/xampp-ssl-encrypt-passwords
---
And that's it! :-)
You know should have a collaboration server up and running.
Thanks to all the authors of the used open-source projects and references. Keep up the good work!
The most unstable component is StatusNet. I'm looking forward to a (stable) version 1.0.
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