Movilización alrededor de lo que está pasando en México. No podemos seguir como espectadores agraviados nada más. Algo podemos hacer, al menos, expresar públicamente nuestro desacuerdo.
Archive for the 'Uncategorized' Category
27
Jun
11
Hegel, Kojève and Lacan
En el fin de semana, más que conversar, un amigo psicoanalista y yo mencionamos un poco sobre Hegel y el psicoanálisis. Hoy buscando un poco sobre el tema, me encontré un artículo bien escrito sobre el particular. Desgraciadamente no encontré las otras partes que prometía el autor sobre el mismo tema. Si tienen tiempo e interés, échenle un oclayo: Hegel, Kojève and Lacan – The Metamorphoses of Dialectics – Part I: Hegel’s Phenomenology of Spirit and its Kojevian Interpretation as a Point of Reference for the Psychoanalytic Theory of Jacques Lacan
¡Salud!
Una reflexión que encuentro fresca en medio de la revolución pagana y teatralmente politeísta de las últimas horas. Una sacudida a mis recuerdos, a las reflexiones que me construyeron y que algún día me sacaron del delirio del progreso.
Básicamente es pasar de un problema de seguridad nacional a un problema de salud. De un problema de represión a uno de elección. Claro, la represión no requiere educación, al contrario, le estorba; sin embargo, la elección inteligente, la requiere. Libertad y educación: otra vez ese binomio que tanto ha ayudado al hombre: no sé por qué lo olvidamos tan a menudo.
via malversando.blog
11
Apr
11
Hilary Hahn + Bach
07
Nov
04
Some useful W3C documents
HTTP GET/POST
When I interview somebody for a web-related technical position, I use to ask what the differences between GET and POST are. I have heard almost all creative (but wrong) answers about that, but very few guys have answered it quiet well.
Besides the HTTP specification where it is stated that the capital difference between those methods (GET is semantically idempotent, POST isn’t) and a lot of consequences, fortunately today I found an article (a finding they call) from the Technical Architecture Group (TAG) that will help to understand those consequences about the intrinsic difference by exposing well documented examples as to reinforce the specification points regards this topic. The whole TAG findings list is also available.
Architecture of the World Wide Web as a W3C Proposed Recommendation
These guys stated that the Architecture of the World Wide Web was a Proposed Recommendation. This is a very well documented reference for those who want to get the benefits of a number of recommendations from the W3C on their web sites or applications. This is also a TAG work.
XML Binary Characterization Use Cases
A lot have been said about the overhead XML impose to the communication layer in a number of architectures. Well, W3C is working on an initiative that goals in provide an alternative serialization method in order to alleviate this issue. Currently they are grouping all the different XML use cases, and ask the community to provide some cases they are missing. Personally, I found that they miss EDI/XML and ASN.1 XML use cases. I already emailed this observation.
25
Oct
04
RFID Passports
As almost any bad idea about security, this one also comes from the Bush Administration: Promoting RFID Passports. A RFID passport would broadcast your ID. It will be readable by any RFID reader. Read more about it on this post of the Bruce Schneier blog.
Thanks Arcadi for the typo observation.
Mauricio Castro let me know about an Open Letter to President Bush on U.S. Economic Policy. It is already signed by two Nobel laureates among 113 Business and Economics emeritus professors from a number of the most important schools along USA. It’s a great letter that everybody, at least in USA, should read.
It’s very common that whenever you need to synchronize on a String value (for example, a username) you must synchronize on a common single object for all the intances of Strings that are Object.equals(Object) among them (you need to synchronize concurrent access to the system for the same user). Also it’s very common to choose this common single object as the value of a Hashtable with the keySet being the String values.
Lets code it:
Map lockMap=new Hashtable();
//…
public boolean createWorkspace(String username) {
synchronize(getCommon(username)) {
//your stuff
}
}
//…
//does not work!
private Object getCommon(String value) {
Object common=lockMap.get(value);
if(common==null) {
common=new Object();
lockMap.put(value,common);
}
return common;
}
This won’t work because if two thread with the same username has just one line of difference they could return different “common” objects. The following doesn’t work either for the same reason. Two different threads with the same value can enter into the if.
//doesn’t work either!
private Object getCommon(String value) {
if(lockMap.get(value)==null) {
lockMap.put(value,new Object());
}
return lockMap.get(value);
}
So it seems that the only solution is to synchronize the whole method, whether on the lockMap object or on the instance of our code (suppose it’s a singleton). The code should be something like:
private Object getCommon(String value) {
synchronized(lockMap) {
Object common=lockMap.get(value);
if(common==null) {
common=new Object();
lockMap.put(value,common);
}
return common;
}
}
And you maybe ask: what’s the problem here? Well, the problem is that in some point of our system we are synchronizing (pausing) all threads when we just wanted to pause the threads that have the same username value. And we are doing this with all the users that want to use the system. So we are in a bottleneck scenario, so the problem here is performance.
So, what to do? Well, for a very unknown reason there is a String method that is almost unknown among all Java developers. This method have been in the String class at least since JDK 1.1 (but I’m almost sure I saw it in the very old 1.0.2, but at the moment of writing this post, this version wasn’t available in the Archive: Java Technology Products Download page) The method documentation says
Returns a canonical representation for the string object.
A pool of strings, initially empty, is maintained privately by the class String.
When the intern method is invoked, if the pool already contains a string equal to this String object as determined by the equals(Object) method, then the string from the pool is returned. Otherwise, this String object is added to the pool and a reference to this String object is returned.
It follows that for any two strings s and t,
s.intern() == t.intern()is true if and only if s.equals(t) is true.
All literal strings and string-valued constant expressions are interned. String literals are defined in §3.10.5 of the Java Language Specification
Returns:a string that has the same contents as this string, but is guaranteed to be from a pool of unique strings.
So, we should code as the following:
public boolean createWorkspace(String username) {
synchronize(username.intern()) {
//your stuff
}
}
I used this aproximation about three years ago on an entry point of a online e-banking application, and worked quite well. Now, looking in the web about this solution I found that this was the topic of the Question of the week Number 158 of the developers.sun.com more or less 30 weeks ago.
15
Sep
04
Bonobos
This article Bonobo Sex and Society, which was originally published by Scientific American is an excellent resource about Bonobos. I’m convinced that every human being should read about these close relatives.
Afterwards, you can read more about bonobos going through the book Bonobo: The Forgotten Ape. Both, the book and article were written by the same author: Frans de Waal.
15
Sep
04
Comparación
Imaginemos a una madre de familia haciendo que diariamente todos sus hijos digan al unísono algo muy agradable a su padre con una invitación del estilo: “Todos digan: te amamos mucho, papá”, justo cuando el papá llega a desayunar. Ahora añadamos a la escena el hecho de que el papá se la cree y de hecho realmente disfruta de que los niños hagan ese esfuerzo, aunque realmente como que los niños no hagan el esfuerzo de aprenderse exactamente las palabras que deben decir en ese momento. Pero eso no importa, el papá se la cree y realmente se siente amado por sus hijos.
Ok, ahora comparemos eso al hecho semanal de un sacerdote que dice en muchos momentos de la Misa: “Respondemos todos: Bendito seas por siempre, Señor”. Imagínense qué clase de deidad debiera ser para creersela y pensar que está cool que todos repitan así la liturgia. Pues esa es la clase de deidad que promueve el catolicismo… o por lo menos un buen número de sacerdotes católico. Sinceramente me pregunto qué crerán los sacerdotes que gana para su dios y su gloria el hecho de que todos repitan después de él la frase correcta. Claramente es un asunto religioso, esto es, la que gana ahí es la religión y con ello el fortalecimiento del vínculo entre la conciencia y los estatutos morales que rigen los valores de esa religión. Pero la pregunta persiste: ¿qué tiene que ver una religión con una deidad? ¿qué podríamos saber de una deidad a través de religiones o ministros de ese calibre?
Sin duda, un asunto penoso. Sobretodo si se reflexiona sobre los elementos tan mezquinos con los que se amarran a las conciencias de los hombres y las mujeres que caen en ese trinomio culpa-arrepentimiento-perdón.
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