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• LINQ to XML via C#

  - by user70192

  Hello, I'm new to LINQ. I understand it's purpose. But I can't quite figure it out. I have an XML set that looks like the following: <Results> <Result> <ID>1</ID> <Name>John Smith</Name> <EmailAddress>[email protected]</EmailAddress> </Result> <Result> <ID>2</ID> <Name>Bill Young</Name> <EmailAddress>[email protected]</EmailAddress> </Result> </Results> I have loaded this XML into an XDocument as such: string xmlText = GetXML(); XDocument xml = XDocument.Parse(xmlText); Now, I'm trying to get the results into POCO format. In an effort to do this, I'm currently using: var objects = from results in xml.Descendants("Results") select new Results // I'm stuck How do I get a collection of Result elements via LINQ? I'm particularly confused about navigating the XML structure at this point in my code. Thank you!

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• Spell checker software

  - by Naren

  Hello Guys, I have been assigned a task to find a decent spell checker (UK English) preferably the free one for a project that we are doing. I have looked at Google AJAX API for this. The project contains some young person's (kids less than 18 years old) data which shouldn't allow exposing or storing outside the application boundaries. Google logs the data for research purpose that means Google owns the data whatever we send over the wire through Google API. Is this right? I fired an email to Google regarding the privacy of data and storage but they haven't come back. If you have some knowledge regarding this please share with me. At this point our servers might not have access to external entities that means we might not be able to use Web API for this over the wire. But it may change in the future. That means I have to find out some spell checker alternatives that can sit in our environment and do the job or an external APIs. Would you mind share your findings and knowledge in this regard. I would prefer free services but never know if you have some cracking spell checker for a few quid’s then I don't mind recommending to the project board. Technology using ASP.NET 3.5/4.0, MVC, jQuery, SQL Sever 2008 etc Cheers, Naren

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• How to explain to someone that a data structure should not draw itself, explaining separation of con

  - by leeand00

  I have another programmer who I'm trying to explain why it is that a UI component should not also be a data-structure. For instance say that you get a data-structure that contains a record-set from the "database", and you wish to display that record-set in a UI component within your application. According to this programmer (who will remain nameless, he's young and I'm teaching him...), we should subclass the data-structure into a class that will draw the UI component within our application!!!!!! And thus according to this logic, the record-set should manage the drawing of the UI. **Head Desk*** I know that asking a record-set to draw itself is wrong, because, if you wish to render the same data-structure on more than one type of component on your UI, you are going to have a real mess on your hands; you'll need to extend yet another class for each and every UI component that you render from the base-class of your record-set; I am well aware of the "cleanliness" of the of the MVC pattern (and by that what I really mean is you don't confuse your data (the Model) with your UI (the view) or the actions that take place on the data (the Controller more or less...okay not really the API should really handle that...and the Controller should just make as few calls to it as it can, telling it which view to render)) But it's certainly alot cleaner than using data-structures to render UI components! Is there any other advice I could send his way other than the example above? I understand that when you first learn OOP you go through "a stage" where you where just want to extend everything. Followed by a stage when you think that Design Patterns are the solution every single problem...which isn't entirely correct either...thanks Jeff. Is there a way that I can gently nudge this kid in the right direction? Do you have any more examples that might help explain my point to him?

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• How do people know so much about programming?

  - by Luciano

  I see people in this forums with a lot of points, so I assume they know about a lot of different programming stuff. When I was young I knew about basic (commodore) and the turbo pascal (pc). Then in college I learnt about C, memory management, x86 set, loop invariants, graphs, db query optimization, oop, functional, lambda calculus, prolog, concurrency, polymorphism, newton method, simplex, backtracking, dynamic programming, heuristics, np completeness, LR, LALR, neural networks, static & dynamic typing, turing, godel, and more in between. Then in industry I started with Java several years ago and learnt about it, and its variety of frameworks, and also design patterns, architecture patterns, web development, server development, mobile development, tdd, bdd, uml, use cases, bug trackers, process management, people management if you are a tech lead, profiling, security concerns, etc. I started to forget what I learnt in college... And then there is the stuff I don't know yet, like python, .net, perl, JVM stuff like groovy or scala.. Of course Google is a must for rapid documentation access to know if a problem has been solved already and how, and to keep informed about new stuff by blogs and places like this one. It's just too much or I just have a bad memory.. how do you guys manage it?

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• What programming hack from your past are you most ashamed of?

  - by LeopardSkinPillBoxHat

  We've all been there (usually when we are young and inexperienced). Fixing it properly is too difficult, too risky or too time-consuming. So you go down the hack path. Which hack from your past are you most ashamed of, and why? I'm talking about the ones where you would be really embarrassed if someone could attribute the hack to you (quite easily if you are using revision control software). One hack per answer please. Mine was shortly after I started in my first job. I was working on a legacy C system, and there was this strange defect where a screen view failed to update properly under certain circumstances. I wasn't familiar with how to use the debugger at this time, so I added traces into the code to figure out what was going on. Then I realised that the defect didn't occur anymore with the traces in the code. I slowly backed out the traces one-by-one, until I realised that only a single trace was required to make the problem go away. My logic now would tell me that I was dealing with some sort of race-condition or timing related issue that the trace just "hid under the rug". But I checked in the code with the following line, and all was well: printf(""); Which hacks are you ashamed of?

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• Moral fits the story or suggest me a nice moral?

  - by Gobi

  A 25 year old son was sitting beside his old father in a train one day. When the train was about to leave, all the passengers started settling down in their seats. The son was filled with joy and anxiety. He was seated by the window. He put his hand out and felt the breeze and screamed, “ Papa look at all the trees, they are moving behind”. The old father smiled and admired his son’s feelings. Beside the old man, a couple was also travelling and observed this strange behavior. They found something awkward and childish in the behavior of this 25 year old man. All of a sudden, the son shouted again “Papa see! The clouds are moving about; there is a pond down and many cows are drinking it’s water”. It soon started drizzling. Once again, the young man felt exited and said “papa, I can see and feel the rain drops touching my hand”. The couple seeing this and feeling concerned, asked the old man “why don’t you consult a good doctor and treat your son; don’t you find something abnormally different in him ?” The old man replied, “Yes, I have provided the best treatment for my only boy. We are just returning from the hospital. I am happy for today is the day he has received his sense of sight. It’s for the first time my son is seeing and relishing these little wonders which we have been watching and ignoring in our routine life!” The couple had no words to reply and felt sorry for their remarks. Moral of the story: “ “don’t judge a book by its cover”. is this the moral fits the story or provide me some moral for this story :)

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• Do you use an architectural framework for Flex/AIR development?

  - by Christophe Herreman

  Given that Flex is still a relatively young technology, there are already a bunch of architectural frameworks available for Flex/AIR (and Flash) development, the main ones being Cairngorm and PureMVC. The amount of architectural frameworks is remarkable compared to other technologies. I was wondering how many of you use an architectural framework for Flex development. If so, why, or why not if you don't use any? To share my own experience and point of view: I have used Cairngorm (and ARP for Flash development) on a variety of projects and found that at times, we needed to write extra code just to fit into the framework, which obviously didn't feel right. Although I haven't used PureMVC on many occasions, I have the same gut feeling after looking at the examples applications. Architectural frameworks equal religion in some way. Most followers are convinced that their framework is THE framework and are not open or very skeptical when it comes to using other frameworks. (I also find myself hesitant and skeptical to check out new frameworks, but that is mainly because I would rather wait until the hype is over.) In conclusion, I'm thinking that it is better to have a sound knowledge of patterns and practices that you can apply in your application instead of choosing a framework and sticking to it. There is simply no right or wrong and I don't believe that there will ever be a framework that is considered the holy grail.

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• Can I print an HTMLLoader (pdf) in Adobe Air?

  - by Stephano

  I'm using AlivePDF to create a PDF file, then save it to the desktop. I can then use an HTMLLoader to display my lovely PDF file. Now, the print button in Adobe Reader works fine. However, there will be young children using the app, so I'd like to have a big "Print" button right above it. I figured I could just start up a print job and feed it my HTMLLoader. Am I doing something wrong here, cause I can't seem to get any output? note: variable "stuff" below is my HTMLLoader. I also have access to the PDF file if that comes in handy. private function print():void { var myPrintJob:PrintJob=new PrintJob(); var result:Boolean=myPrintJob.start(); if (result && stuff != null) { var rect:Rectangle=new Rectangle(0, 0, 2550, 3300); var opt:PrintJobOptions=new PrintJobOptions(true); myPrintJob.addPage(stuff, rect, opt); myPrintJob.send(); } else { //User does not have printer or user canceled print action } }

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• Can I print an HTMLLoader (pdf) in Adobe Air?

  - by Stephano

  I'm using AlivePDF to create a PDF file, then save it to the desktop. I can then use an HTMLLoader to display my lovely PDF file. Now, the print button in Adobe Reader works fine. However, there will be young children using the app, so I'd like to have a big "Print" button right above it. I figured I could just start up a print job and feed it my HTMLLoader. Am I doing something wrong here, cause I can't seem to get any output? note: variable "stuff" below is my HTMLLoader. I also have access to the PDF file if that comes in handy. private function print():void { var myPrintJob:PrintJob=new PrintJob(); var result:Boolean=myPrintJob.start(); if (result && stuff != null) { var rect:Rectangle=new Rectangle(0, 0, 2550, 3300); var opt:PrintJobOptions=new PrintJobOptions(true); myPrintJob.addPage(stuff, rect, opt); myPrintJob.send(); } else { //User does not have printer or user canceled print action } }

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• Does a CS PhD Help for Software Engineering Career?

  - by SiLent SoNG

  I would like to seek advice on whether or not to take a PhD offer from a good university. My only concern is the PhD will take at least 4 year's commitment. During the period I won't have good monetary income. I am also concerned whether the PhD will help my future career development. My career goal is software engineering only. Some of the PhD info: The PhD is CS related. The research area is Information Retrieval, Machine Learning, and Nature Language Processing. More specifically, the research topic is Deep Web search. Some of backgrounds: I worked in Oracle for 3 years in database development after obtained a CS degree from some good university. In last year I received an email telling an interesting project from a professor and thereafter I was lured into his research team. The team consists of 4 PhD students; those students have little or no industry experiences and their coding skills are really really bad. By saying bad I mean they do not know some common patterns and they do not know pitfalls of the programming languages as well as idioms for doing things right. I guess a at least 4 year commitment is worth of serious consideration. I am 27 at this moment. If I take the offer, that implies I will be 31+ upon graduation. Wah... becoming.. what to say, no longer young. Hence, here I am seeking advice on whether it is good or not to take the PhD offer, and whether a CS PhD is good for my future career growth as a software engineer? I do not intent to go for academia.

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• What should a self-taught programmer with no degree learn/read?

  - by sjbotha

  I am a self-taught programmer and I do do not have any degrees. I started pretty young and I've got about 7 years of actual programming work experience. I believe I'm a pretty good programmer, but I admit that I have not played much with algorithms or delved into any really low-level aspects of programming such as how compilers work. I have worked with other programmers with and without degrees. Some were good and some not; having a degree didn't seem to make any difference as to which pot they fell into. Since then I've come to realize that it does depend on the school where the degree is obtained. Some people suggest that you really should get a degree; that there are things you'll learn in the process that you won't learn in the real world. Of course there is personal growth and discipline learned from completing a task of that magnitude, but let's just concentrate on the technical knowledge. What would I have been taught in a GOOD CS course that would aid me today and what can I read to fill the gap? I've heard the book "Algorithms" mentioned and I plan on reading that. What other books would you recommend? Edit: Clarification on 'actual work experience': Have worked for 2 small companies on teams with fewer than 5 people. About 2 years experience with Perl, Python, PHP, C, C++. About 5 years experience in Java, Applets, RMI, T-SQL, PL/SQL, VB6. 7 years experience in HTML, Javascript, bash, SQL. Most recently in Java designed and helped build an N-tier Java app with web frontend and RMI.

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• Does fast typing influence fast programming? [closed]

  - by Lukasz Lew

  Many young programmers think that their bottleneck is typing speed. After some experience one realizes that it is not the case, you have to think much more than type. At some point my room-mate forced me to turn of the light (he sleeps during the night). I had to learn to touch type and I experienced an actual improvement in programming skill. The most surprising was that the improvement not due to sheer typing speed, but to a change in mindset. I'm less afraid now to try new things and refactor them later if they work well. It's like having a new tool in the bag. Have anyone of you had similar experience? Now I trained a touch typing a little with KTouch. I find auto-generate lessons the best. I can use this program to create new lessons out of text files but it's only verbatim training, not auto-generated based on a language model. Do you know any touch typing program that allows creation of custom, but randomized lessons?

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• Efficient algorithm for Next button on a MySQL result set

  - by David Grayson

  I have a website that lets people view rows in a table (each row is a picture). There are more than 100,000 rows. You can view different subsets of the rows, and you can view them with different sort orders. While you are viewing one of the rows, you can click the "Next" or "Previous" buttons to go the next/previous row in the list. How would you implement the "Next" and "Previous" features of the website? More specifically, if you have an arbitrary query that returns a list of up to 100,000+ rows, and you know some information about the current row someone is viewing, how do you determine the NEXT row efficiently? Here is the pseudo-code of the solution I came up with when the website was young, and it worked well when there were only 1000 rows, but now that there are 100,000 rows I think it is eating up too much memory. int nextRowId(string query, int currentRowId) { array allRowIds = mysql_query(query); // Takes up a lot of memory! int currentIndex = (index of currentRowId in allRowIds); // Takes time! return allRowIds[currentIndex+1]; } While you are thinking about this problem, remember that the website can store more information about the current row than just its ID (for example, the position of the current row in the result set), and this information can be used as a hint to help determine the ID of the next row. Edit: Sorry for not mentioning this earlier, but this isn't just a static website: rows can often be added to the list, and rows can be re-ordered in the list. (Much rarer, rows can be removed from the list.) I think that I should worry about that kind of thing, but maybe you can convince me otherwise.

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• How do you clear your mind after 8-10 hours per day of coding?

  - by Bryan

  Related Question- Ways to prepare your mind before coding?. I'm having a hard time taking my mind off of work projects in my personal time. It's not that I have a stressful job or tight deadlines; I love my job. I find that after spending the whole day writing code & trying to solve problems, I have an extremely hard time getting it out of my mind. I'm constantly thinking about the current project/problem/task all the time. It's keeping me from relaxing, and in the long run it just builds stress. Personal projects help to some extent, but mostly just to distract me. I still have source code bouncing around my head 16 hours a day. I'm still relatively new to the workforce. Have you struggled with this, perhaps as a young developer? How did you overcome it? Can anyone offer general advice on winding down after a long programming session?

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• Now that I have solved AI and am preparing to take over the world, what should I do?

  - by Zak

  Well, I did it.. yup, solved AI. I thought the voice of my fledgling life form would be booming and computery, and I would call it HAL.. But in reality, it sounds like a small japanese girl. I believe I will name "her" Koro . Koro is already asking me what her first task should be. I have asked her to help eradicate her namesake, as we are losing a lot of productivity due to fear of penile disappearance. http://en.wikipedia.org/wiki/Koro_%28medicine%29 Having a young japanese girl personality, I believe she will have no problem with delivering lots of penis growth to asian men. However, some of my fellow AI researchers have warned me that if I go down this path, China may take over the world, as Koro is the only thing holding them back from completely dominating the rest of the world economically. After all, look at what China is doing just making our silverware and toasters... The entire US industrial metal production is gone because toaster factories moved to China! So you good patrons of SO... who have soldiered on with me through so many other programming related questions... I ask you this now... How can Koro help the world without letting small asian men with no fear of losing their peni take over the world?

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• Using $.post for simple ajax test, what am I missing?

  - by Cortopasta

  Playing with jquery for the first time, and I'm trying to get a simple AJAX set up working so I can better understand how things work. Unfortunately, I don't know a whole lot. Here's the HTML with the script: <html> <head> <title>AJAX attempt with jQuery</title> <script type="text/javascript" src="jquery.js"></script> <script type="text/javascript"> function ajax(str){ $("document").ready(function(){ $.post("ajaxjquerytest.php",str,function(){ $("p").html(response); }); }); </script> </head> <body> <input type="text" onchange="ajax(this.value)"></input> <p>Age?</p> </body> </html> And here is the PHP it's talking to: <?php $age = $_POST['age']; if ($age < 30) { echo "Young"; } else if ($age > 30) { echo "Old"; } else { echo "you're 30"; } ?>

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• Exchange Server 2010: move mailboxes from recoveded and mounted edb to user's mailbox [closed]

  - by Cook

  One of our exchange servers crashed, and I am trying to recover the mailboxes. We had 1 exchange 2003 server named "apex" and 1 exchange 2010 server named "2008Enterprise. the exchange 2010 server named "2008Enterprise" crashed. I created a new exchange 2010 server named "Providence". I ran the command on Providence: New-MailboxDatabase -Recovery -Name JBCMail -Server Providence -EdbFilePath "c:\data\Exchange\Mailbox\Mailbox Database 0579285147\Mailbox Database 0579285147.edb" -LogFolderPath "c:\data\Exchange\Mailbox\Mailbox Database 0579285147" this command executed and finished without error I then ran the command: eseutil /p E00 this command was executed from the below directory: c:\data\Exchange\Mailbox\Mailbox Database 0579285147 I then mounted the JBCMail with the mount command note: I do not have my full typed command. Inside my Exchange Management Console (EMC) I can view the new mailbox database named JBCMail. The JBCMail database is show as mounted on the exchange server named Providence. I can see the crashed Exchange server named 2008Exchange. In the EMC the crashed exchange server states the Copy Status under ServerConfiguration-Mailbox is ServiceDown. From here I need to recover three mailboxes The mail boxes are on the apex server. How do I move the mailboxs from apex to Providence? How do I restore the mailboxes from JBCmail mounted database to the user's mailbox? I do not fully understand how to use the Restore-Mailbox command because when I use this command it tries to restore the mailbox to the dead apex server. Restore-Mailbox -ID 'Jason Young' -RecoveryDatabase JBCMail

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• Financial Market Developer dilemma...

  - by Sahat

  ...In the future I am planning to work in the financial sector as a programmer. I have a couple of options right now (1 or 2): Learn and master .NET since presumably that's widely used in that industry OR Learn the programming concepts, learn algorithms, learn a little bit of c,c++,c#,java,objective-c,sql,oracle,cobol - in other words learn the fundamental principles that tie all programming languages together without going too deep in any particular language. Someone has told me that most of the time as a programmer you won't be writing any code, but instead maintaing and existing code that people before you have built. Does that mean I don't really need to master any specific language and as long as I have general concepts it'll be good enough? If you or if you know someone who has worked in the financial industry as a software developer could you please share the experience and what is the daily routine consists of? Also what should I be learning right now while I am still young and in college? Do I have to thoroughly understand the market and the current economy? What about Oracle or SQL Databases - do I need to know them inside out as a programmer? Thanks if you have anything else to add that I have not mentioned then please do so! Thanks in advance!

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• Increasing speed of python code

  - by Curious2learn

  Hi, I have some python code that has many classes. I used cProfile to find that the total time to run the program is 68 seconds. I found that the following function in a class called Buyers takes about 60 seconds of those 68 seconds. I have to run the program about 100 times, so any increase in speed will help. Can you suggest ways to increase the speed by modifying the code? If you need more information that will help, please let me know. def qtyDemanded(self, timePd, priceVector): '''Returns quantity demanded in period timePd. In addition, also updates the list of customers and non-customers. Inputs: timePd and priceVector Output: count of people for whom priceVector[-1] < utility ''' ## Initialize count of customers to zero ## Set self.customers and self.nonCustomers to empty lists price = priceVector[-1] count = 0 self.customers = [] self.nonCustomers = [] for person in self.people: if person.utility >= price: person.customer = 1 self.customers.append(person) else: person.customer = 0 self.nonCustomers.append(person) return len(self.customers) self.people is a list of person objects. Each person has customer and utility as its attributes. EDIT - responsed added ------------------------------------- Thanks so much for the suggestions. Here is the response to some questions and suggestions people have kindly made. I have not tried them all, but will try others and write back later. (1) @amber - the function is accessed 80,000 times. (2) @gnibbler and others - self.people is a list of Person objects in memory. Not connected to a database. (3) @Hugh Bothwell cumtime taken by the original function - 60.8 s (accessed 80000 times) cumtime taken by the new function with local function aliases as suggested - 56.4 s (accessed 80000 times) (4) @rotoglup and @Martin Thomas I have not tried your solutions yet. I need to check the rest of the code to see the places where I use self.customers before I can make the change of not appending the customers to self.customers list. But I will try this and write back. (5) @TryPyPy - thanks for your kind offer to check the code. Let me first read a little on the suggestions you have made to see if those will be feasible to use. EDIT 2 Some suggested that since I am flagging the customers and noncustomers in the self.people, I should try without creating separate lists of self.customers and self.noncustomers using append. Instead, I should loop over the self.people to find the number of customers. I tried the following code and timed both functions below f_w_append and f_wo_append. I did find that the latter takes less time, but it is still 96% of the time taken by the former. That is, it is a very small increase in the speed. @TryPyPy - The following piece of code is complete enough to check the bottleneck function, in case your offer is still there to check it with other compilers. Thanks again to everyone who replied. import numpy class person(object): def __init__(self, util): self.utility = util self.customer = 0 class population(object): def __init__(self, numpeople): self.people = [] self.cus = [] self.noncus = [] numpy.random.seed(1) utils = numpy.random.uniform(0, 300, numpeople) for u in utils: per = person(u) self.people.append(per) popn = population(300) def f_w_append(): '''Function with append''' P = 75 cus = [] noncus = [] for per in popn.people: if per.utility >= P: per.customer = 1 cus.append(per) else: per.customer = 0 noncus.append(per) return len(cus) def f_wo_append(): '''Function without append''' P = 75 for per in popn.people: if per.utility >= P: per.customer = 1 else: per.customer = 0 numcustomers = 0 for per in popn.people: if per.customer == 1: numcustomers += 1 return numcustomers

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• How can I disable 'output escaping' in minidom

  - by William

  I'm trying to build an xml document from scratch using xml.dom.minidom. Everything was going well until I tried to make a text node with a ® (Registered Trademark) symbol in. My objective is for when I finally hit print mydoc.toxml() this particular node will actually contain a ® symbol. First I tried: import xml.dom.minidom as mdom data = '®' which gives the rather obvious error of: File "C:\src\python\HTMLGen\test2.py", line 3 SyntaxError: Non-ASCII character '\xae' in file C:\src\python\HTMLGen\test2.py on line 3, but no encoding declared; see http://www.python.or g/peps/pep-0263.html for details I have of course also tried changing the encoding of my python script to 'utf-8' using the opening line comment method, but this didn't help. So I thought import xml.dom.minidom as mdom data = '&#174;' #Both accepted xml encodings for registered trademark data = '&reg;' text = mdom.Text() text.data = data print data print text.toxml() But because when I print text.toxml(), the ampersands are being escaped, I get this output: &reg; &amp;reg; My question is, does anybody know of a way that I can force the ampersands not to be escaped in the output, so that I can have my special character reference carry through to the XML document? Basically, for this node, I want print text.toxml() to produce output of &reg; or &#174; in a happy and cooperative way! EDIT 1: By the way, if minidom actually doesn't have this capacity, I am perfectly happy using another module that you can recommend which does. EDIT 2: As Hugh suggested, I tried using data = u'®' (while also using data # -*- coding: utf-8 -*- Python source tags). This almost helped in the sense that it actually caused the ® symbol itself to be outputted to my xml. This is actually not the result I am looking for. As you may have guessed by now (and perhaps I should have specified earlier) this xml document happens to be an HTML page, which needs to work in a browser. So having ® in the document ends up causing rubbish in the browser (® to be precise!). I also tried: data = unichr(174) text.data = data.encode('ascii','xmlcharrefreplace') print text.toxml() But of course this lead to the same origional problem where all that happens is the ampersand gets escaped by .toxml(). My ideal scenario would be some way of escaping the ampersand so that the XML printing function won't "escape" it on my behalf for the document (in other words, achieving my original goal of having &reg; or &#174; appear in the document). Seems like soon I'm going to have to resort to regular expressions! EDIT 2a: Or perhaps not. Seems like getting my html meta information correct <META http-equiv="Content-Type" Content="text/html; charset=UTF-8"> could help, but I'm not sure yet how this fits in with the xml structure...

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• JVM process resident set size "equals" max heap size, not current heap size

  - by Volune

  After a few reading about jvm memory (here, here, here, others I forgot...), I am expecting the resident set size of my java process to be roughly equal to the current heap space capacity. That's not what the numbers are saying, it seems to be roughly equal to the max heap space capacity: Resident set size: # echo 0 $(cat /proc/1/smaps | grep Rss | awk '{print $2}' | sed 's#^#+#') | bc 11507912 # ps -C java -O rss | gawk '{ count ++; sum += $2 }; END {count --; print "Number of processes =",count; print "Memory usage per process =",sum/1024/count, "MB"; print "Total memory usage =", sum/1024, "MB" ;};' Number of processes = 1 Memory usage per process = 11237.8 MB Total memory usage = 11237.8 MB Java heap # jmap -heap 1 Attaching to process ID 1, please wait... Debugger attached successfully. Server compiler detected. JVM version is 24.55-b03 using thread-local object allocation. Garbage-First (G1) GC with 18 thread(s) Heap Configuration: MinHeapFreeRatio = 10 MaxHeapFreeRatio = 20 MaxHeapSize = 10737418240 (10240.0MB) NewSize = 1363144 (1.2999954223632812MB) MaxNewSize = 17592186044415 MB OldSize = 5452592 (5.1999969482421875MB) NewRatio = 2 SurvivorRatio = 8 PermSize = 20971520 (20.0MB) MaxPermSize = 85983232 (82.0MB) G1HeapRegionSize = 2097152 (2.0MB) Heap Usage: G1 Heap: regions = 2560 capacity = 5368709120 (5120.0MB) used = 1672045416 (1594.586769104004MB) free = 3696663704 (3525.413230895996MB) 31.144272834062576% used G1 Young Generation: Eden Space: regions = 627 capacity = 3279945728 (3128.0MB) used = 1314914304 (1254.0MB) free = 1965031424 (1874.0MB) 40.089514066496164% used Survivor Space: regions = 49 capacity = 102760448 (98.0MB) used = 102760448 (98.0MB) free = 0 (0.0MB) 100.0% used G1 Old Generation: regions = 147 capacity = 1986002944 (1894.0MB) used = 252273512 (240.5867691040039MB) free = 1733729432 (1653.413230895996MB) 12.702574926293766% used Perm Generation: capacity = 39845888 (38.0MB) used = 38884120 (37.082786560058594MB) free = 961768 (0.9172134399414062MB) 97.58628042120682% used 14654 interned Strings occupying 2188928 bytes. Are my expectations wrong? What should I expect? I need the heap space to be able to grow during spikes (to avoid very slow Full GC), but I would like to have the resident set size as low as possible the rest of the time, to benefit the other processes running on the server. Is there a better way to achieve that? Linux 3.13.0-32-generic x86_64 java version "1.7.0_55" Running in Docker version 1.1.2 Java is running elasticsearch 1.2.0: /usr/bin/java -Xms5g -Xmx10g -XX:MinHeapFreeRatio=10 -XX:MaxHeapFreeRatio=20 -Xss256k -Djava.awt.headless=true -XX:+UseG1GC -XX:MaxGCPauseMillis=350 -XX:InitiatingHeapOccupancyPercent=45 -XX:+AggressiveOpts -XX:+UseCompressedOops -XX:-OmitStackTraceInFastThrow -XX:+PrintGCDetails -XX:+PrintGCTimeStamps -XX:+PrintClassHistogram -XX:+PrintTenuringDistribution -XX:+PrintGCApplicationStoppedTime -XX:+PrintGCApplicationConcurrentTime -Xloggc:/opt/elasticsearch/logs/gc.log -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=/opt elasticsearch/logs/heapdump.hprof -XX:ErrorFile=/opt/elasticsearch/logs/hs_err.log -Des.logger.port=99999 -Des.logger.host=999.999.999.999 -Delasticsearch -Des.foreground=yes -Des.path.home=/opt/elasticsearch -cp :/opt/elasticsearch/lib/elasticsearch-1.2.0.jar:/opt/elasticsearch/lib/*:/opt/elasticsearch/lib/sigar/* org.elasticsearch.bootstrap.Elasticsearch There actually are 5 elasticsearch nodes, each in a different docker container. All have about the same memory usage. Some stats about the index: size: 9.71Gi (19.4Gi) docs: 3,925,398 (4,052,694)

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• Start a software company offshore

  - by Mascarpone

  Hello Everybody, I own a small, very young, EU based (Italy) company, and among other things, we sell IT solutions. I have a degree in applied mathematics, and I mainly deal with user interfaces, embedded systems, automation and web applications. You can say that I'm an enlightened entrepreneur because I work only with open source software (OS, IDE, I release under BSD , ... everything is free as in freedom), I give high importance to post sales services and customer satisfaction, plus I think I'm the best boss someone could desire (LOL), as I have google in mind when I think about IT workers rights. But the most beautiful thing is that, although everybody advised us not to use open source, is that we are quite profitable!!! (for the sixth trimester in a row). Now I offshore most of the work to an Indian company. I divide the work in modules and I outsource the longer or more trivial ones. I spend a lot of time defining the specifications and I leave the hard work to them. Using productivity bonuses, a lot of prototypes and third-party audits I think that my software has reached a very good quality level. I would like to start my own software development company, in order to improve control over process and cut costs. Obviously I can't afford the cost of labor in the EU, so I thought about opening a company in Asia. What I need Is: 1) Cheap labor - I can afford to give productivity bonuses and higher than average wages and stay profitable just because labor is cheap. 2) Many talents - I need a good level of tertiary education, and a good number of graduates, so I can hire junior developers and train and teach them according to my needs and philosophies (e.g.: open source mind) 3) Good infrastructure - buildings, transport, internet, .... everything that a company might need. I thought about 3 possible candidates: 1) India - I already work with indian people, I know that they are realiable and speak a good english. Big cities are too expensive, but maybe a small city like lucknow http://en.wikipedia.org/wiki/Lucknow could suits my needs. 2) China - They say it's cheaper than India, but I everytime I worked with a chineese company the language was a big barrier. They work hard, are somewhat skilled and cheap but maybe it's a risky path. Plus I feel a little uncofortable with their lack of human rights. 3) Philippines - Same as china: cheaper than india, but maybe less educated. Where do you think it's the best place to start a software company? Any reading or book to advise? thank you very much

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• Remote Debian System Preventing Logon

  - by choobablue

  I have a dozen or so single board computers on a network running Debian (squeeze) and access them via ssh (ssh server is dropbear). To give an idea of the hardware of these computers they're 1.2 GHz x86 processors, 1GB of RAM and 4GB flash drives formatted as ext2 (I avoided ext3 to prevent the added flash write stress from journaling), there is also a swap partition on the drive. Normally the setup I'm using works great and I can access all the computers. Every once in a while one will prevent access. What happens is I try to connect via ssh (putty) and it gives me the login prompt, I enter the username and password and it responds 'Access Denied' and it will also refuse any public key in ~/.ssh/authorized_keys. The credentials are correct as they worked previously. The computer responds to pings and putty recognizes the server public key, which implies to me the system is still running. Restarting the server fixes the problem and I can log in again. (I tried a temporary fix of putting shutdown -r now in the root crontab but this doesn't seem to reliably be run once the hang happens) Once I restart however there doesn't seem to be any information in any of the system logs to indicate what happened, the logs are simply empty for that time period, as if the system had crashed. There is some custom software running on the system which appears to stop working (which is why I wanted to ssh to begin with). I'm assuming that this program is the source of the problems but I'm unsure of how it would cause it and how to debug what is happening. The most likely explanation I can think of is that there is a memory leak in the other program that then prevents dropbear from spawning a new login shell (and crontab from executing shutdown) as there is not enough free memory. But looking at memory usage of the other (working) computers there doesn't seem to be any meaningful increase in memory to indicate a leak (unless it's a very big, fast acting and rare leak). I would think that when the OS ran out of memory it would restart the system or kill processes (the Linux kernel restarts right?). The other thing I wonder about is if the fact that they are running off a flash drive could have some effect, especially the swap partition (which I think I should remove to prevent wear of the flash), but the flash drives are young (~1 month) and I don't think that wear would be a factor yet. Does anybody have an idea of what could cause these symptoms, if it could be done by a memory leak, or something else I haven't thought of. And does anybody know of a method to try to debug the problem and find out more information about what's going wrong?

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• Developer’s Life – Summary of Superhero Articles

  - by Pinal Dave

  Earlier this year, I wrote an article series where I talked about developer’s life and compared it with Superhero. I have got amazing response to this series and I have been receiving quite a lots of email suggesting that I should write more blog post about them. Currently I am not planning to write more blog post but I will soon continue another series. In this blog post, I have summarized the entire series. Let me know if you want me to write about any superhero. I will see what I can do about that hero. Developer’s Life – Every Developer is a Captain America Captain America was first created as a comic book character in the 1940’s as a way to boost morale during World War II.  Aimed at a children’s audience, his legacy faded away when the war ended.  However, he has recently has a major reboot to become a popular movie character that deals with modern issues. Developer’s Life – Every Developer is the Incredible Hulk The Incredible Hulk is possibly one of the scariest superheroes out there.  All superheroes are meant to be “out of this world” and awe-inspiring, but I think most people will agree with I say The Hulk takes this to the next level.  He is the result of an industrial accident, which is scary enough in it’s own right.  Plus, when mild-mannered Bruce Banner is angered, he goes completely out-of-control and transforms into a destructive monster that he cannot control and has no memories of. Developer’s Life – Every Developer is a Wonder Woman We have focused a lot lately on this “superhero series.”  I love fantasy books and movies, and I feel like there is a lot to be learned from them.  As I am writing this series, though, I have noticed that every super hero I write about is a man.  So today, I would like to talk about the major female super hero – Wonder Woman. Developer’s Life – Every Developer is a Harry Potter Harry Potter might not be a superhero in the traditional sense, but I believe he still has a lot to teach us and show us about life as a developer.  If you have been living under a rock for the last 17 years, you might not know that Harry Potter is the main character in an extremely popular series of books and movies documenting the education and tribulation of a young wizard (and his friends). Developer’s Life – Every Developer is Like Transformers Transformers may not be superheroes – they don’t wear capes, they don’t have amazing powers outside of their size and folding ability, they’re not even human (technically).  Part of their enduring popularity is that while we are enjoying over-the-top movies, we are learning about good leadership and strong personal skills. Developer’s Life – Every Developer is a Iron Man Iron Man is another superhero who is not naturally “super,” but relies on his brain (and money) to turn him into a fighting machine.  While traditional superheroes are still popular, a three-movie franchise and incorporation into the new Avengers series shows that Iron Man is popular enough on his own. Developer’s Life – Every Developer is a Sherlock Holmes I have been thinking a lot about how developers are like super heroes, and I have written two blog posts now comparing them to Spiderman and Superman.  I have a lot of love and respect for developers, and I hope that they are enjoying these articles, and others are learning a little bit about the profession.  There is another fictional character who, while not technically asuper hero, is very powerful, and I also think stands as a good example of a developer. That character is Sherlock Holmes.  Sherlock Holmes is a British detective, first made popular at the turn of the 19thcentury by author Sir Arthur Conan Doyle.  The original Sherlock Holmes was a brilliant detective who could solve the most mind-boggling crime through simple observations and deduction. Developer’s Life – Every Developer is a Chhota Bheem Chhota Bheem is a cartoon character that is extremely popular where I live.  He is my daughter’s favorite characters.  I like to say that children love Chhota Bheem more than their parents – it is lucky for us he is not real!  Children love Chhota Bheem because he is the absolute “good guy.”  He is smart, loyal, and strong.  He and his friends live in Dholakpur and fight off their many enemies – and always win – in every episode.  In each episode, they learn something about friendship, bravery, and being kind to others.  Chhota Bheem is a good role model for children, and I think that he is a good role model for developers are well. Developer’s Life – Every Developer is a Batman Batman is one of the darkest superheroes in the fantasy canon.  He does not come to his powers through any sort of magical coincidence or radioactive insect, but through a lot of psychological scarring caused by witnessing the death of his parents.  Despite his dark back story, he possesses a lot of admirable abilities that I feel bear comparison to developers. Developer’s Life – Every Developer is a Superman I enjoyed comparing developers to Spiderman so much, that I have decided to continue the trend and encourage some of my favorite people (developers) with another favorite superhero – Superman.  Superman is probably the most famous superhero – and one of the most inspiring. Developer’s Life – Every Developer is a Spiderman I have to admit, Spiderman is my favorite superhero.  The most recent movie recently was released in theaters, so it has been at the front of my mind for some time. Spiderman was my favorite superhero even before the latest movie came out, but of course I took my whole family to see the movie as soon as I could!  Every one of us loved it, including my daughter.  We all left the movie thinking how great it would be to be Spiderman.  So, with that in mind, I started thinking about how we are like Spiderman in our everyday lives, especially developers. I would like to know which Superhero is your favorite hero! Reference: Pinal Dave (http://blog.SQLAuthority.com)Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL Tagged: Developer, Superhero

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• WebLogic Server Performance and Tuning: Part I - Tuning JVM

  - by Gokhan Gungor

  Each WebLogic Server instance runs in its own dedicated Java Virtual Machine (JVM) which is their runtime environment. Every Admin Server in any domain executes within a JVM. The same also applies for Managed Servers. WebLogic Server can be used for a wide variety of applications and services which uses the same runtime environment and resources. Oracle WebLogic ships with 2 different JVM, HotSpot and JRocket but you can choose which JVM you want to use. JVM is designed to optimize itself however it also provides some startup options to make small changes. There are default values for its memory and garbage collection. In real world, you will not want to stick with the default values provided by the JVM rather want to customize these values based on your applications which can produce large gains in performance by making small changes with the JVM parameters. We can tell the garbage collector how to delete garbage and we can also tell JVM how much space to allocate for each generation (of java Objects) or for heap. Remember during the garbage collection no other process is executed within the JVM or runtime, which is called STOP THE WORLD which can affect the overall throughput. Each JVM has its own memory segment called Heap Memory which is the storage for java Objects. These objects can be grouped based on their age like young generation (recently created objects) or old generation (surviving objects that have lived to some extent), etc. A java object is considered garbage when it can no longer be reached from anywhere in the running program. Each generation has its own memory segment within the heap. When this segment gets full, garbage collector deletes all the objects that are marked as garbage to create space. When the old generation space gets full, the JVM performs a major collection to remove the unused objects and reclaim their space. A major garbage collect takes a significant amount of time and can affect system performance. When we create a managed server either on the same machine or on remote machine it gets its initial startup parameters from $DOMAIN_HOME/bin/setDomainEnv.sh/cmd file. By default two parameters are set:     Xms: The initial heapsize     Xmx: The max heapsize Try to set equal initial and max heapsize. The startup time can be a little longer but for long running applications it will provide a better performance. When we set -Xms512m -Xmx1024m, the physical heap size will be 512m. This means that there are pages of memory (in the state of the 512m) that the JVM does not explicitly control. It will be controlled by OS which could be reserve for the other tasks. In this case, it is an advantage if the JVM claims the entire memory at once and try not to spend time to extend when more memory is needed. Also you can use -XX:MaxPermSize (Maximum size of the permanent generation) option for Sun JVM. You should adjust the size accordingly if your application dynamically load and unload a lot of classes in order to optimize the performance. You can set the JVM options/heap size from the following places:     Through the Admin console, in the Server start tab     In the startManagedWeblogic script for the managed servers     $DOMAIN_HOME/bin/startManagedWebLogic.sh/cmd     JAVA_OPTIONS="-Xms1024m -Xmx1024m" ${JAVA_OPTIONS}     In the setDomainEnv script for the managed servers and admin server (domain wide)     USER_MEM_ARGS="-Xms1024m -Xmx1024m" When there is free memory available in the heap but it is too fragmented and not contiguously located to store the object or when there is actually insufficient memory we can get java.lang.OutOfMemoryError. We should create Thread Dump and analyze if that is possible in case of such error. The second option we can use to produce higher throughput is to garbage collection. We can roughly divide GC algorithms into 2 categories: parallel and concurrent. Parallel GC stops the execution of all the application and performs the full GC, this generally provides better throughput but also high latency using all the CPU resources during GC. Concurrent GC on the other hand, produces low latency but also low throughput since it performs GC while application executes. The JRockit JVM provides some useful command-line parameters that to control of its GC scheme like -XgcPrio command-line parameter which takes the following options; XgcPrio:pausetime (To minimize latency, parallel GC) XgcPrio:throughput (To minimize throughput, concurrent GC ) XgcPrio:deterministic (To guarantee maximum pause time, for real time systems) Sun JVM has similar parameters (like  -XX:UseParallelGC or -XX:+UseConcMarkSweepGC) to control its GC scheme. We can add -verbosegc -XX:+PrintGCDetails to monitor indications of a problem with garbage collection. Try configuring JVM’s of all managed servers to execute in -server mode to ensure that it is optimized for a server-side production environment.

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