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• C#: A "Dumbed-Down" C++?

  - by James Michael Hare

  I was spending a lovely day this last weekend watching my sons play outside in one of the better weekends we've had here in Saint Louis for quite some time, and whilst watching them and making sure no limbs were broken or eyes poked out with sticks and other various potential injuries, I was perusing (in the correct sense of the word) this month's MSDN magazine to get a sense of the latest VS2010 features in both IDE and in languages. When I got to the back pages, I saw a wonderful article by David S. Platt entitled, "In Praise of Dumbing Down"  (msdn.microsoft.com/en-us/magazine/ee336129.aspx).  The title captivated me and I read it and found myself agreeing with it completely especially as it related to my first post on divorcing C++ as my favorite language. Unfortunately, as Mr. Platt mentions, the term dumbing-down has negative connotations, but is really and truly a good thing.  You are, in essence, taking something that is extremely complex and reducing it to something that is much easier to use and far less error prone.  Adding safeties to power tools and anti-kick mechanisms to chainsaws are in some sense "dumbing them down" to the common user -- but that also makes them safer and more accessible for the common user.  This was exactly my point with C++ and C#.  I did not mean to infer that C++ was not a useful or good language, but that in a very high percentage of cases, is too complex and error prone for the job at hand. Choosing the correct programming language for a job is a lot like choosing any other tool for a task.  For example: if I want to dig a French drain in my lawn, I can attempt to use a huge tractor-like backhoe and the job would be done far quicker than if I would dig it by hand.  I can't deny that the backhoe has the raw power and speed to perform.  But you also cannot deny that my chances of injury or chances of severing utility lines or other resources climb at an exponential rate inverse to the amount of training I may have on that machinery. Is C++ a powerful tool?  Oh yes, and it's great for those tasks where speed and performance are paramount.  But for most of us, it's the wrong tool.  And keep in mind, I say this even though I have 17 years of experience in using it and feel myself highly adept in utilizing its features both in the standard libraries, the STL, and in supplemental libraries such as BOOST.  Which, although greatly help with adding powerful features quickly, do very little to curb the relative dangers of the language. So, you may say, the fault is in the developer, that if the developer had some higher skills or if we only hired C++ experts this would not be an issue.  Now, I will concede there is some truth to this.  Obviously, the higher skilled C++ developers you hire the better the chance they will produce highly performant and error-free code.  However, what good is that to the average developer who cannot afford a full stable of C++ experts? That's my point with C#:  It's like a kinder, gentler C++.  It gives you nearly the same speed, and in many ways even more power than C++, and it gives you a much softer cushion for novices to fall against if they code less-than-optimally.  A bug is a bug, of course, in any language, but C# does a good job of hiding and taking on the task of handling almost all of the resource issues that make C++ so tricky.  For my money, C# is much more maintainable, more feature-rich, second only slightly in performance, faster to market, and -- last but not least -- safer and easier to use.  That's why, where I work, I much prefer to see the developers moving to C#.  The quantity of bugs is much lower, and we don't need to hire "experts" to achieve the same results since the language itself handles those resource pitfalls so prevalent in poorly written C++ code.  C++ will still have its place in the world, and I'm sure I'll still use it now and again where it is truly the correct tool for the job, but for nearly every other project C# is a wonderfully "dumbed-down" version of C++ -- in the very best sense -- and to me, that's the smart choice.

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• The battle between Java vs. C#

  The battle between Java vs. C# has been a big debate amongst the development community over the last few years. Both languages have specific pros and cons based on the needs of a particular project. In general both languages utilize a similar coding syntax that is based on C++, and offer developers similar functionality. This being said, the communities supporting each of these languages are very different. The divide amongst the communities is much like the political divide in America, where the Java community would represent the Democrats and the .Net community would represent the Republicans. The Democratic Party is a proponent of the working class and the general population. Currently, Java is deeply entrenched in the open source community that is distributed freely to anyone who has an interest in using it. Open source communities rely on developers to keep it alive by constantly contributing code to make applications better; essentially they develop code by the community. This is in stark contrast to the C# community that is typically a pay to play community meaning that you must pay for code that you want to use because it is developed as products to be marketed and sold for a profit. This ties back into my reference to the Republicans because they typically represent the needs of business and personal responsibility. This is emphasized by the belief that code is a commodity and that it can be sold for a profit which is in direct conflict to the laissez-faire beliefs of the open source community. Beyond the general differences between Java and C#, they also target two different environments. Java is developed to be environment independent and only requires that users have a Java virtual machine running in order for the java code to execute. C# on the other hand typically targets any system running a windows operating system and has the appropriate version of the .Net Framework installed. However, recently there has been push by a segment of the Open source community based around the Mono project that lets C# code run on other non-windows operating systems. In addition, another feature of C# is that it compiles into an intermediate language, and this is what is executed when the program runs. Because C# is reduced down to an intermediate language called Common Language Runtime (CLR) it can be combined with other languages that are also compiled in to the CLR like Visual Basic (VB) .Net, and F#. The allowance and interaction between multiple languages in the .Net Framework enables projects to utilize existing code bases regardless of the actual syntax because they can be compiled in to CLR and executed as one codebase. As a software engineer I personally feel that it is really important to learn as many languages as you can or at least be open to learn as many languages as you can because no one language will work in every situation.  In some cases Java may be a better choice for a project and others may be C#. It really depends on the requirements of a project and the time constraints. In addition, I feel that is really important to concentrate on understanding the logic of programming and be able to translate business requirements into technical requirements. If you can understand both programming logic and business requirements then deciding which language to use is just basically choosing what syntax to write for a given business problem or need. In regards to code refactoring and dynamic languages it really does not matter. Eventually all projects will be refactored or decommissioned to allow for progress. This is the way of life in the software development industry. The language of a project should not be chosen based on the fact that a project will eventually be refactored because they all will get refactored.

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• The long road to bug-free software

  - by Tony Davis

  The past decade has seen a burgeoning interest in functional programming languages such as Haskell or, in the Microsoft world, F#. Though still on the periphery of mainstream programming, functional programming concepts are gradually seeping into the imperative C# language (for example, Lambda expressions have their root in functional programming). One of the more interesting concepts from functional programming languages is the use of formal methods, the lofty ideal behind which is bug-free software. The idea is that we write a specification that describes exactly how our function (say) should behave. We then prove that our function conforms to it, and in doing so have proved beyond any doubt that it is free from bugs. All programmers already use one form of specification, specifically their programming language's type system. If a value has a specific type then, in a type-safe language, the compiler guarantees that value cannot be an instance of a different type. Many extensions to existing type systems, such as generics in Java and .NET, extend the range of programs that can be type-checked. Unfortunately, type systems can only prevent some bugs. To take a classic problem of retrieving an index value from an array, since the type system doesn't specify the length of the array, the compiler has no way of knowing that a request for the "value of index 4" from an array of only two elements is "unsafe". We restore safety via exception handling, but the ideal type system will prevent us from doing anything that is unsafe in the first place and this is where we start to borrow ideas from a language such as Haskell, with its concept of "dependent types". If the type of an array includes its length, we can ensure that any index accesses into the array are valid. The problem is that we now need to carry around the length of arrays and the values of indices throughout our code so that it can be type-checked. In general, writing the specification to prove a positive property, even for a problem very amenable to specification, such as a simple sorting algorithm, turns out to be very hard and the specification will be different for every program. Extend this to writing a specification for, say, Microsoft Word and we can see that the specification would end up being no simpler, and therefore no less buggy, than the implementation. Fortunately, it is easier to write a specification that proves that a program doesn't have certain, specific and undesirable properties, such as infinite loops or accesses to the wrong bit of memory. If we can write the specifications to prove that a program is immune to such problems, we could reuse them in many places. The problem is the lack of specification "provers" that can do this without a lot of manual intervention (i.e. hints from the programmer). All this might feel a very long way off, but computing power and our understanding of the theory of "provers" advances quickly, and Microsoft is doing some of it already. Via their Terminator research project they have started to prove that their device drivers will always terminate, and in so doing have suddenly eliminated a vast range of possible bugs. This is a huge step forward from saying, "we've tested it lots and it seems fine". What do you think? What might be good targets for specification and verification? SQL could be one: the cost of a bug in SQL Server is quite high given how many important systems rely on it, so there's a good incentive to eliminate bugs, even at high initial cost. [Many thanks to Mike Williamson for guidance and useful conversations during the writing of this piece] Cheers, Tony.

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• The long road to bug-free software

  - by Tony Davis

  The past decade has seen a burgeoning interest in functional programming languages such as Haskell or, in the Microsoft world, F#. Though still on the periphery of mainstream programming, functional programming concepts are gradually seeping into the imperative C# language (for example, Lambda expressions have their root in functional programming). One of the more interesting concepts from functional programming languages is the use of formal methods, the lofty ideal behind which is bug-free software. The idea is that we write a specification that describes exactly how our function (say) should behave. We then prove that our function conforms to it, and in doing so have proved beyond any doubt that it is free from bugs. All programmers already use one form of specification, specifically their programming language's type system. If a value has a specific type then, in a type-safe language, the compiler guarantees that value cannot be an instance of a different type. Many extensions to existing type systems, such as generics in Java and .NET, extend the range of programs that can be type-checked. Unfortunately, type systems can only prevent some bugs. To take a classic problem of retrieving an index value from an array, since the type system doesn't specify the length of the array, the compiler has no way of knowing that a request for the "value of index 4" from an array of only two elements is "unsafe". We restore safety via exception handling, but the ideal type system will prevent us from doing anything that is unsafe in the first place and this is where we start to borrow ideas from a language such as Haskell, with its concept of "dependent types". If the type of an array includes its length, we can ensure that any index accesses into the array are valid. The problem is that we now need to carry around the length of arrays and the values of indices throughout our code so that it can be type-checked. In general, writing the specification to prove a positive property, even for a problem very amenable to specification, such as a simple sorting algorithm, turns out to be very hard and the specification will be different for every program. Extend this to writing a specification for, say, Microsoft Word and we can see that the specification would end up being no simpler, and therefore no less buggy, than the implementation. Fortunately, it is easier to write a specification that proves that a program doesn't have certain, specific and undesirable properties, such as infinite loops or accesses to the wrong bit of memory. If we can write the specifications to prove that a program is immune to such problems, we could reuse them in many places. The problem is the lack of specification "provers" that can do this without a lot of manual intervention (i.e. hints from the programmer). All this might feel a very long way off, but computing power and our understanding of the theory of "provers" advances quickly, and Microsoft is doing some of it already. Via their Terminator research project they have started to prove that their device drivers will always terminate, and in so doing have suddenly eliminated a vast range of possible bugs. This is a huge step forward from saying, "we've tested it lots and it seems fine". What do you think? What might be good targets for specification and verification? SQL could be one: the cost of a bug in SQL Server is quite high given how many important systems rely on it, so there's a good incentive to eliminate bugs, even at high initial cost. [Many thanks to Mike Williamson for guidance and useful conversations during the writing of this piece] Cheers, Tony.

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• .NET Framework installation requirements

  - by Paja

  What are the requirements for all .NET frameworks and their service packs? This is what I need to know for all available frameworks: .NET Framework prerequisites What other .NET Frameworks does it require? For example: .NET Framework 2.0 does not require anything, .NET Framework 2.0 SP1 requires .NET Framework 2.0 installed, but .NET Framework 3.5 SP1 does not require .NET Framework 3.5 installed (or maybe does? dunno) Reboot requirements Does the installation package require reboot after installation? Clean install requirements Does the installation package require clean install? (No pending delete/rename operations) Administrator privileges Does the installation package require administrator privileges to install? (I guess this is "yes" for all of them...) And I need to know all of this for the following packages: .NET Framework 1.1 .NET Framework 1.1 Language Pack .NET Framework 1.1 SP 1 .NET Framework 2.0 .NET Framework 2.0 Language Pack .NET Framework 2.0 SP 1 .NET Framework 2.0 SP 1 Language Pack .NET Framework 2.0 SP 2 .NET Framework 2.0 SP 2 Language Pack .NET Framework 3.5 .NET Framework 3.5 Language Pack .NET Framework 3.5 SP 1 .NET Framework 3.5 SP 1 Language Pack .NET Framework 4.0 Full .NET Framework 4.0 Client Could you please either tell me all of these requirements, or direct me to the appropriate source? Or maybe both? :-)

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• cakephp, i18n .po files, How to use them correctly

  - by ion

  I have finally managed to set up a multilingual cakephp site. Although not finished it is the first time where I can change the DEFAULT_LANGUAGE in the bootstrap and I can see the language to change. My problem right now is that I cannot understand very well how to use the po files correctly. According to the tutorials I've used I need to create a folder /app/locale and inside that folder create a folder for each language in the following format: /locale/eng/LC_MESSAGES. I have done that and I have also managed to extract a default.pot file using cake i18n extract. And it appears that all occurrences of the __() function have been found succesfully. In my application I'm using 2 languages: eng and gre. I can see why you would need a seperate folder for each language. However in my case nothing happens when I edit the po files inside each folder....well almost nothing. If I edit the /app/locale/gre/LC_MESSAGES/default.po I have no language changes. If I edit the /app/locale/eng/LC_MESSAGES/default.po then the language changes to the new value (on the translation field) and it does not switch to the other language. What am I doing wrong. I hope I made myself as clear as possible.

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• Exiting from the Middle of an Expression Without Using Exceptions

  - by Jon Purdy

  Is there a way to emulate the use of flow-control constructs in the middle of an expression? Is it possible, in a comma-delimited expression x, y, for y to cause a return? Edit: I'm working on a compiler for something rather similar to a functional language, and the target language is C++. Everything is an expression in the source language, and the sanest, simplest translation to the destination language leaves as many things expressions as possible. Basically, semicolons in the target language become C++ commas. In-language flow-control constructs have presented no problems thus far; it's only return. I just need a way to prematurely exit a comma-delimited expression, and I'd prefer not to use exceptions unless someone can show me that they don't have excessive overhead in this situation. The problem of course is that most flow-control constructs are not legal expressions in C++. The only solution I've found so far is something like this: try { return x(), // x(); (1 ? throw Return(0) : 0); // return 0; } catch (Return& ret) { return ref.value; } The return statement is always there (in the event that a Return construct is not reached), and as such the throw has to be wrapped in ?: to get the compiler to shut up about its void result being used in an expression. I would really like to avoid using exceptions for flow control, unless in this case it can be shown that no particular overhead is incurred; does throwing an exception cause unwinding or anything here? This code needs to run with reasonable efficiency. I just need a function-level equivalent of exit().

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• Which Stroustrup book should I use?

  - by Chris Simmons

  I'm a C# programmer that is looking to branch out. I'm bored of writing business software and want to start getting into graphics programming and games/simulators. So I figured, although writing that stuff isn't impossible in managed code, the "right" way to do that would be to look to C++, of course focussing on the language first, then getting into OpenGL or DirectX (or whatever). Way way back ('98? '99?) I had tried and failed to really grasp Stroustrup's The C++ Programming Language. I know that this book is often not recommended for the beginner. Anyway, I picked it back up (in a much more recent printing) and I'm actually getting it and enjoying it. I also have a copy of his textbook, Programming: Principles and Practice Using C++, which, as I understand it, is really geared toward teaching programming, not necessarily C++. I'm certainly not arrogant enough to claim I don't have anything more to learn about programming, data structures, algoriths, etc., however I'm not a novice there either. So my question is, with the goal of gaining the broader and more real-world-useful understanding of C++ and given my background, on which should I focus? The denser (as I perceive it) TCPPPL or the gentler Programming? EDIT: I thank everyone for the responses. However, I've got a personal choice here to make between these two books. Granted there are other very good books out there, but I'm already a good length into both of the books I mention and I'd like to finish one. So, can anyone respond on which would be the better and why? Time is not an issue; I'm not looking (at this point) at an "accelerated" read.

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• Have to click twice to submit the form

  - by phil

  Intended function: require user to select an option from the drop down menu. After user clicks submit button, validate if an option is selected. Display error message and not submit the form if user fails to select. Otherwise submit the form. Problem: After select an option, button has to be clicked twice to submit the form. I have no clue at all.. <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <script src="jquery-1.4.2.min.js" type="text/javascript"></script> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <style> p{display: none;} </style> </head> <script> $(function(){ // language as an array var language=['Arabic','Cantonese','Chinese','English','French','German','Greek','Hebrew','Hindi','Italian','Japanese','Korean','Malay','Polish','Portuguese','Russian','Spanish','Thai','Turkish','Urdu','Vietnamese']; $('#muyu').append('<option value=0>Select</option>'); //loop through array for (i in language) //js unique statement for iterate array { $('#muyu').append($('<option>',{id:'muyu'+i,val:language[i], html:language[i]})) } $('form').submit(function(){ alert('I am being called!'); // check if submit event is triggered if ( $('#muyu').val()==0 ) {$('#muyu_error').show(); } else {$('#muyu_error').hide(); return true;} return false; }) }) </script> <form method="post" action="match.php"> I am fluent in <select name='muyu' id='muyu'></select> <p id='muyu_error'>Tell us your native language</p> <input type="submit" value="Go"> </form>

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• read contents of a xml file into a data grid view

  - by syedsaleemss

  Im using c# .net , windows form application. I have a XML file which contains two columns and some rows of data. now i have to fill this data into a data grid view. im using a button, when i click on the button an open dialog box will appear. i have to select the xml file name and when i click on open the contents of that xml file should come to the data grid view. i have tried with the following code: { XmlDataDocument xmlDatadoc=new XmlDataDocument(); XmlDatadoc.Dataset.ReadXml(filename); ds=xmlDatadoc.Dataset; datagridview1.DataSource=ds.DefaultViewManager; datagridview1.Datamember="language"; } My xml file is: <languages> <language> <key> key1</key> <value>value1</value> <language> <language> <key> key2</key> <value>value2</value> <language> </languages> Its working fine but only for "language" . I need it to work file other xml files also.

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• Small Open source and free java applications

  - by user1089770

  I am a Perl Developer who has just stepped into the Java world and I want to be very proficient in Java EE development. However, I have found that, being a Perl guy, I have very high MTI(Mother Tongue Influence). Indians will know what MTI is. For others, it can be defined as an influence of your "main" language whenever you "speak" your new language. In other words, our mind converts/translates what we want to "say" in the new language based on the "main" language, which can be quite absurd or meaning less in the "new" language. Coming back to the point, as a result of this MTI, many lines of my code has this Perl influence and it is absurd and useless for production. Hence, I'd like to see or better do some research on existing small to medium open source java applications, so that I will know how I can "speak" in the native way of the "new" language. Some examples in PHP will be : WordPress, Zend etc. So I'd really appreciate if you guys could suggest any such apps. Apps that have a great commercial value are highly preferred

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• Passing contextual info to Views in ASP.NET MVC

  - by Andrey

  I wonder - what is the best way to supply contextual (i.e. not related to any particular view, but to all views at the same time) info to a view (or to master page)? Consider the following scenario. Suppose we have an app that supports multiple UI languages. User can switch them via UI's widgets (something like tabs at the top of the page). Each language is rendered as a separate tab. Tab for the current language should not be rendered. To address these requirements I'm planning to have a javascript piece that will hide current's language tab on the client. To do this, I need current's language tab Id on the client. So, I need some way of passing the Id to master page (for it to be 'fused' into the js script). The best thing I can think of is that all my ViewModels should inherit some ViewModeBase that has a field to hold current language tab Id. Then, whatever View I'm rendering, this Id will always be available for the master page's hiding script. However, I'm concerned that this ViewModelBase can potentially grow in an uncontrolled fashion as number of such pieces of contextual info (like current language) will grow.. Any ideas?

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• Adding International support in Erlang Web 1.4

  - by Roberto Aloi

  I'm trying to add international support for a website based on the Erlang Web 1.4. I would like to have a couple of links on every page (the notorious Country flags) that allow the user to set his language session variable. What I have right now is a link like: <li><a href="/session/language/en">English</a></li> Where, in the session controller I do: language(Args) -> LanguageId = proplists:get_value(id, Args), case language_is_supported(LanguageId) of false -> ok; true -> wpart:fset("session:lang", LanguageId) end, {redirect, "/"}. The problem is that, after setting the preferred language, I would like the user to be redirected to the page he was visiting before changing the language. In this case the "__path" variable doesn't help because it contains the language request and not the "previous" one. How could I resolve this situation? I'm probably using the wrong approach but I cannot thing to anything else right now.

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• Translate Languages in IE 8 with Bing Translator

  - by Asian Angel

  Do you need side by side or hover language translations while browsing? Then join us as we look at the Bing Translator accelerator for Internet Explorer 8. Note: This article is geared towards those who may not have used this accelerator before or declined to “add it” when setting up IE 8. Using Bing Translator Once you have clicked on Add to Internet Explorer and confirmed the installation your new accelerator is ready to use. For our example we chose a Norwegian news article. Right-click within the webpage to access the context menu entry for translating. Depending on the originating language, you may want to go ahead and set it manually before beginning the translation. The translation will be opened in a new tab… Note: The same entry can also be accessed through the All Accelerators listing. There are four settings available for viewing your translations: side by side, top/bottom, original with hover translation, & translation with hover original. First a look at the side by side view. When maximized the window area will be divided 50/50 and as you hover your mouse or scroll in one side the same action will occur simultaneously in the other side. The top/bottom view. As above browser actions occur simultaneously in both sections. The original with hover translation view. Especially helpful if you are studying a new language and want to check your level of understanding for the original language. The translation with original hover view. Four different viewing options make it easy to find the one that best suits your needs. Conclusion If you need a convenient way to translate between languages in Internet Explorer 8, then the Bing Translator accelerator just might be what you have been looking for. Links Add the Bing Translator accelerator to Internet Explorer 8 Similar Articles Productive Geek Tips Quickly Translate Text to Another Language in Word 2007Add Google Translation Power to FirefoxTranslate Foreign Website Text to your Native LanguageAuto Translate Text in Google ChromeView Word Definitions in IE 8 with the Define with Bing Accelerator TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips HippoRemote Pro 2.2 Xobni Plus for Outlook All My Movies 5.9 CloudBerry Online Backup 1.5 for Windows Home Server 24 Million Sites Windows Media Player Glass Icons (icons we like) How to Forecast Weather, without Gadgets Outlook Tools, one stop tweaking for any Outlook version Zoofs, find the most popular tweeted YouTube videos Video preview of new Windows Live Essentials

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• Mono for Android Book has been Released!!!!!

  - by Wallym

  If I understand things correctly, and I make no guarantees that I do, our Mono for Android book has been RELEASED!  I'm not quite sure what this means, but my guess is that that it has been printed and is being shipped to various book sellers.So, if you have pre-ordered a copy, its now up to Amazon to send it to you.  Its fully out of my control, Wrox, Wiley, as well as everyone but Amazon.If you haven't bought a copy already, why?  Seriously, go order 8-10 copies for the ones you love.  They'll make great romantic gifts for the ones you love.  Just think at the look on the other person's face when you give them a copy of our book. Here's a little about the book:The wait is over! For the millions of .NET/C# developers who have been eagerly awaiting the book that will guide them through the white-hot field of Android application programming, this is the book. As the first guide to focus on Mono for Android, this must-have resource dives into writing applications against Mono with C# and compiling executables that run on the Android family of devices.Putting the proven Wrox Professional format into practice, the authors provide you with the knowledge you need to become a successful Android application developer without having to learn another programming language. You'll explore screen controls, UI development, tables and layouts, and MonoDevelop as you become adept at developing Android applications with Mono for Android.Develop Android apps using tools you already know—C# and .NETAimed at providing readers with a thorough, reliable resource that guides them through the field of Android application programming, this must-have book shows how to write applications using Mono with C# that run on the Android family of devices. A team of authors provides you with the knowledge you need to become a successful Android application developer without having to learn another programming language. You'll explore screen controls, UI development, tables and layouts, and MonoDevelop as you become adept at planning, building, and developing Android applications with Mono for Android.Professional Android Programming with Mono for Android and .NET/C#:Shows you how to use your existing C# and .NET skills to build Android appsDetails optimal ways to work with data and bind data to controlsExplains how to program with Android device hardwareDives into working with the file system and application preferencesDiscusses how to share code between Mono for Android, MonoTouch, and Windows® Phone 7Reveals tips for globalizing your apps with internationalization and localization supportCovers development of tablet apps with Android 4Wrox Professional guides are planned and written by working programmers to meet the real-world needs of programmers, developers, and IT professionals. Focused and relevant, they address the issues technology professionals face every day. They provide examples, practical solutions, and expert education in new technologies, all designed to help programmers do a better job.Now, go buy a bunch of copies!!!!!If you are interested in iPhone and Android and would like to get a little more knowledgeable in the area of development, you can purchase the 3 pack of books from Wrox on Mobile Development with Mono.  This will cover MonoTouch, Mono for Android, and cross platform methods for using both tools.  A great package in and of itself.  The name of that package is: Wrox Cross Platform Android and iOS Mobile Development Three-Pack 

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• Big Data – Interacting with Hadoop – What is PIG? – What is PIG Latin? – Day 16 of 21

  - by Pinal Dave

  In yesterday’s blog post we learned the importance of the HIVE in Big Data Story. In this article we will understand what is PIG and PIG Latin in Big Data Story. Yahoo started working on Pig for their application deployment on Hadoop. The goal of Yahoo to manage their unstructured data. What is Pig and What is Pig Latin? Pig is a high level platform for creating MapReduce programs used with Hadoop and the language we use for this platform is called PIG Latin. The pig was designed to make Hadoop more user-friendly and approachable by power-users and nondevelopers. PIG is an interactive execution environment supporting Pig Latin language. The language Pig Latin has supported loading and processing of input data with series of transforming to produce desired results. PIG has two different execution environments 1) Local Mode – In this case all the scripts run on a single machine. 2) Hadoop – In this case all the scripts run on Hadoop Cluster. Pig Latin vs SQL Pig essentially creates set of map and reduce jobs under the hoods. Due to same users does not have to now write, compile and build solution for Big Data. The pig is very similar to SQL in many ways. The Ping Latin language provide an abstraction layer over the data. It focuses on the data and not the structure under the hood. Pig Latin is a very powerful language and it can do various operations like loading and storing data, streaming data, filtering data as well various data operations related to strings. The major difference between SQL and Pig Latin is that PIG is procedural and SQL is declarative. In simpler words, Pig Latin is very similar to SQ Lexecution plan and that makes it much easier for programmers to build various processes. Whereas SQL handles trees naturally, Pig Latin follows directed acyclic graph (DAG). DAGs is used to model several different kinds of structures in mathematics and computer science. DAG Tomorrow In tomorrow’s blog post we will discuss about very important components of the Big Data Ecosystem – Zookeeper. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Big Data, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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• Oracle Linux Training Across Five Continents

  - by Antoinette O'Sullivan

  The Oracle Linux System Administration course, a top selling course, provides you with a broad selection of key competencies you need to be a great Linux system administrator. And you can now take this course from your desk or in classrooms across all five contents. You can take this 5-day instructor-led course through the follow delivery methods: Training-on-Demand: Start training within 24 hours of registering. You following lecture material at your own pace via streaming video and book time on a lab environment to suit your schedule. Live-Virtual Event: Follow a live event from your own desk, no travel required. You can choose from a selection of events on the schedule to suit a different time zones. In-Class Event: Travel to an education center to take this course. Below is a selection of the in-class events already on the schedule. AFRICA  Location  Date  Delivery Language  Nairobi, Kenya  13 October 2014  English  Johannesburg, South Africa  24 November 2014  English AMERICA  Location  Date  Delivery Language  Mississauga, Canada  27 October 2014  English  Chicago, IL, United States  13 October 2014  English  Roseville, MN, United States  13 October 2014  English ASIA  Location  Date  Delivery  Jakarta, Indonesia  20 October 2014  English  Petaling Jaya, Malaysia  25 August 2014  English  Kuala Lumpur, Malaysia  8 December 2014  English  Istanbul, Turkey  10 November 2014  Turkish   Dubai, United Arab Emirates  4 January 2015  English AUSTRALIA  Location  Date  Delivery Language  Canberra, Australia  20 October 2014  English  Melbourne, Australia  20 October 2014  English EUROPE  Location  Date  Delivery Language  Paris, France  6 October 2014  French  Milan, Italy  20 October 2014  Italian  Rome, Italy  8 September 2014  Italian  Bucharest, Romania  27 October 2014  Romanian  Madrid, Spain  1 September 2014  Spanish The Oracle Linux System Administration course is the recommended training course to prepare for you for the Oracle Linux 5 & 6 System Administrator OCA certification exam. Those who have acquired the skills provided in the Oracle Linux System Administration course, can advance their learning by taking the Oracle Linux Advanced Administration course. You can take this 5-day instructor led course as a live-virtual event or an in-class event. Below is a selection of the in-class events on the schedule:  Location  Date  Delivery Language  Jakarta, Indonesia  27 October 2014  English  Kuala Lumpur, Malaysia  6 October 2014  English  Bangkok, Thailand  20 October 2014  English  Belmont, CA, United States  15 September 2014  English For information on the Oracle Linux curriculum, go to http://oracle.com/education/linux.

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• F# Objects &ndash; Integrating with the other .Net Languages &ndash; Part 1

  - by MarkPearl

  In the next few blog posts I am going to explore objects in F#. Up to now, my dabbling in F# has really been a few liners and while I haven’t reached the point where F# is my language of preference – I am already seeing the benefits of the language when solving certain types of programming problems. For me I believe that the F# language will be used in a silo like architecture and that the real benefit of having F# under your belt is so that you can solve problems that F# lends itself towards and then interact with other .Net languages in doing the rest. When I was still very new to the F# language I did the following post covering how to get F# & C# to talk to each other. Today I am going to use a similar approach to demonstrate the structure of F# objects when inter-operating with other languages. Lets start with an empty F# class … type Person() = class end   Very simple, and all we really have done is declared an object that has nothing in it. We could if we wanted to make an object that takes a constructor with parameters… the code for this would look something like this… type Person =     {         Firstname : string         Lastname : string     }   What’s interesting about this syntax is when you try and interop with this object from another .Net language like C# - you would see the following…   Not only has a constructor been created that accepts two parameters, but Firstname and Lastname are also exposed on the object. Now it’s important to keep in mind that value holders in F# are immutable by default, so you would not be able to change the value of Firstname after the construction of the object – in C# terms it has been set to readonly. One could however explicitly state that the value holders were mutable, which would then allow you to change the values after the actual creation of the object. type Person = { mutable Firstname : string mutable Lastname : string }   Something that bugged me for a while was what if I wanted to have an F# object that requires values in its constructor, but does not expose them as part of the object. After bashing my head for a few moments I came up with the following syntax – which achieves this result. type Person(Firstname : string, Lastname : string) = member v.Fullname = Firstname + " " + Lastname What I haven’t figured out yet is what is the difference between the () & {} brackets when declaring an object.

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• Becoming an Expert MySQL DBA Across Five Continents

  - by Antoinette O'Sullivan

  You can take Oracle's MySQL Database Administrator training on five contents. In this 5-day, live, instructor-led course, you learn to install and optimize the MySQL Server, set up replication and security, perform database backups and performance tuning, and protect MySQL databases. Below is a selection of the in-class events already on the schedule for the MySQL for Database Administrators course. AFRICA  Location  Date  Delivery Language  Nairobi, Kenya  22 July 2013  English  Johannesburg, South Africa  9 December 2013  English AMERICA  Location  Date  Delivery Language  Belmont, California, United States  22 July 2013  English ASIA  Location  Date  Delivery Language  Dehradun, India  11 July 2013  English  Grogol - Jakarta Barat, Indonesia  16 September 2013  English  Makati City, Philippines  5 August 2013  English  Pasig City, Philippines  12 August 2013  English  Istanbul, Turkey  12 August 2013  Turkish AUSTRALIA and OCEANIA  Location  Date  Delivery Language  Sydney, Australia  15 July 2013  English  Auckland, New Zealand  5 August 2013  English  Wellington, New Zealand  15 July 2013  English EUROPE  Location  Date  Delivery Language  London, England  9 September 2013  English  Aix-en-Provence, France  2 December 2013  French  Bordeaux Merignac, France  2 December 2013  French  Puteaux, France  16 September 2013  French  Dresden, Germany  26 August 2013  German  Hamburg, Germany  16 November 2013  German  Munich, Germany  19 August 2013  German  Munster, Germany  9 September 2013  German  Budapest, Hungary  4 November 2013  Hungarian  Belfast, Ireland  16 December 2013  English  Milan, Italy  7 October 2013  Italian  Rome, Italy  16 September 2013  Italian  Utrecht, Netherlands  16 September 2013  English  Warsaw, Poland 5 August 2013  Polish   Lisbon, Portugal  16 September 2013 European Portugese   Barcelona, Spain 30 October 2013  Spanish   Madrid, Spain 4 November 2013  Spanish   Bern, Switzerland  27 November 2013  German  Zurich, Switzerland  27 November 2013  German You can also take this course from your own desk as a live-virtual class, choosing from a wide selection of events already on the schedule suiting different timezones. To register for this course or to learn more about the authentic MySQL curriculum, go to http://oracle.com/education/mysql.

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• Was I wrong about JavaScript?

  - by jboyer

  Yes, I was. Recently, I’ve taken a good hard look at JavaScript. I’ve used it before but mostly in the capacity of web design. Using JQuery to make your web page do cool stuff is different than really creating a JavaScript application using all of the language constructs. What I’m finding as I use it more is that I may have been wrong about my assumptions about it. Let me explain.   I enjoyed doing cool stuff with JQuery but the limited experience with JavaScript as a language coupled with the bad things that I heard about it led me to not have any real interest in it. However, JavaScript is ubiquitous on the web and if I want to do any web development, which I do, I need to learn it. So here I am, diving deep into the language with the help of the JavaScript Fundamentals training course at Pluralsight (great training for a low price) and the JavaScript: The Good Parts book by Douglas Crockford.   Now, there are certainly parts of JavaScript that are bad. I think these are well known by any developer that uses it. The parts that I feel are especially egregious are the following: The global object null vs. undefined truthy and falsy limited (nearly nonexistent) scoping ‘==’ and ‘===’ (I just don’t get the reason for coercion)   However, what I am finding hiding under the covers of the bad things is a good language. I am finding that I am legitimately enjoying JavaScript. This I was not expecting. I’m not going to go into a huge dissertation on what I like about it, but some things include: Object literal notation dynamic typing functional style (JavaScript: The Good Parts describes it as LISP in C clothing) JSON (better than XML) There are parts of JavaScript that seem strange to OOP developers like myself. However, just because it is different or seems strange does not mean it is bad. Some differences are quite interesting and useful.   I feel that it is important for developers to challenge their assumptions and also to be able to admit when they are wrong on a topic. Many different situations can arise that lead to this, such as choosing the wrong technology for a problem’s solution, misunderstanding the requirements, etc. I decided to challenge my assumptions about JavaScript instead of moving straight into CoffeeScript or Dart. After exploring it, I find that I am beginning to enjoy it the more I use it. As long as there are those like Crockford to help guide me in the right way to code in JavaScript, I can create elegant and efficient solutions to problems and add another ‘arrow’ to the ‘quiver’, so to speak. I do still intend to learn CoffeeScript to see what the hub-bub is about, but now I no longer have to be afraid of JavaScript as a legitimate programming language.   Has something similar ever happened to you? Tell me about it in the comments below.

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• Why would I learn C++11, having known C and C++?

  - by Shahbaz

  I am a programmer in C and C++, although I don't stick to either language and write a mixture of the two. Sometimes having code in classes, possibly with operator overloading, or templates and the oh so great STL is obviously a better way. Sometimes use of a simple C function pointer is much much more readable and clear. So I find beauty and practicality in both languages. I don't want to get into the discussion of "If you mix them and compile with a C++ compiler, it's not a mix anymore, it's all C++" I think we all understand what I mean by mixing them. Also, I don't want to talk about C vs C++, this question is all about C++11. C++11 introduces what I think are significant changes to how C++ works, but it has introduced many special cases that change how different features behave in different circumstances, placing restrictions on multiple inheritance, adding lambda functions, etc. I know that at some point in the future, when you say C++ everyone would assume C++11. Much like when you say C nowadays, you most probably mean C99. That makes me consider learning C++11. After all, if I want to continue writing code in C++, I may at some point need to start using those features simply because my colleagues have. Take C for example. After so many years, there are still many people learning and writing code in C. Why? Because the language is good. What good means is that, it follows many of the rules to create a good programming language. So besides being powerful (which easy or hard, almost all programming languages are), C is regular and has few exceptions, if any. C++11 however, I don't think so. I'm not sure that the changes introduced in C++11 are making the language better. So the question is: Why would I learn C++11? Update: My original question in short was: "I like C++, but the new C++11 doesn't look good because of this and this and this. However, deep down something tells me I need to learn it. So, I asked this question here so that someone would help convince me to learn it." However, the zealous people here can't tolerate pointing out a flaw in their language and were not at all constructive in this manner. After the moderator edited the question, it became more like a "So, how about this new C++11?" which was not at all my question. Therefore, in a day or too I am going to delete this question if no one comes up with an actual convincing argument. P.S. If you are interested in knowing what flaws I was talking about, you can edit my question and see the previous edits.

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• How to interview a natural scientist for a dev position?

  - by Silas

  I already did some interviews for my company, mostly computer scientists for dev positions but also some testers and project managers. Now I have to fill a vacancy in our research group within the R&D department (side note: “research” means that we try to solve problems in our professional domain/market niche using software in research projects together with universities, other companies, research centres and end user organisations. It’s not computer science research; we’re not going to solve the P=NP problem). Now we invited a guy holding an MSc in chemistry (with a lot of physics in his CV, too), who never had any computer science lesson. I already talked with him about half an hour at a local university’s career days and there’s no doubt the guy is smart. Also his marks are excellent and he graduated with distinction. For his BSc he needed to teach himself programming in Mathematica and told me believably that he liked programming a lot. Also he solved some physical chemistry problem that I probably don’t understand using his own software, implemented in Mathematica, for his MSc thesis. It includes a GUI and a notable size of 8,000 LoC. He seems to be very attracted by what we’re doing in our research group and to be honest it’s quite difficult for an SME like us to get good people. I also am very interested in hiring him since he could assist me in writing project proposals, reports, doing presentations and so on. He would probably fit to our team, too. The only question left is: How can I check if he will get the programming skills he needs to do software implementation in our projects since this will be a significant part of the job? Of course I will ask him what it is, that is fascinating him about programming. I’ll also ask how he proceeded to write his natural science software and how he structured it. I’ll ask about how he managed to obtain the skills and information about software development he needed. But is there something more I could ask? Something more concrete perhaps? Should I ask him to explain his Mathematica solution? To be clear: I’m not looking for knowledge in a particular language or technology stack. We’re a .NET shop in product development but I want to have a free choice for our research projects. So I’m interested in the meta-competence being able to learn whatever is actually needed. I hope this question is answerable and not open-ended since I really like to know if there is a default way to check for the ability to get further programming skills on the job. If something is not clear to you please give me some comments and let me improve my question.

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• Interesting Topics in Comp. Sci. for New Students?

  - by SoulBeaver

  I hope this is the right forum to ask this question. Last friday I was in a discussion with my professors about the students' lack of motivation and interest in the field of Computer Science. All of the students are enrolled, but through questionnaires and other questions that my professor posed it was revealed that over 90% of all enrolled students are just in it for the reward of getting a job sometime in the future (since it's a growing field with high job potential) I asked my professor for the permission to take over the first couple of lectures and try and motivate, interest and inspire students for the field of Computer Science and programming in particular (this is the Intro to Programming course). This request was granted and I now have a week to come up with a lecture topic for my professor's five groups. My main goal isn't to teach, I just want to get students to be as interested in the field as I am. I want to show them what's possible, what awesome magical things have been done in the field, the future we are heading towards using programming and Comp. Sci. Therefore, I would like to pose this question: I have a few topics, materials and sample projects that I would like to talk about: -- Grace Hopper (It is my hope to interest the female programmers in the class. There are never more than two or three per group and they, more than males, are prone to jumping ship and abandoning Comp. Sci.) -- The Singularity Institute -- Alan Turing -- Robotics -- Programming not as a chore or a must, but the idea that we are, at our core, the nexus to which anything anybody does in the digital world is connected to. We are the problem solvers; we assemble all the parts together and we are the ones that, essentially, make the vision a reality. -- Give them an idea for a programming project which, through the help of the professor, could be significant to every student (I want students to not only feel interested in the topic, but they should feel important, that what they do here makes a difference) Do you have interesting topics worthy of discussion, something I can tell the students which they can get interested about? How would you approach the lecture? If you had 90 minutes worth of time to try and get students interested in the project, what would you do?

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• Career advice: stay with PHP or start a new career in something else ( .Net?)

  - by Christian P

  I'm planning on moving to NY in 6-12 months tops, so I'm forced to find a new job. When I'm planing to start my life in another city it's also probably a good time to think about career changes. I've found a lot of different opinions about PHP vs .Net vs Java and this is not topic here. I don't want to start a new fight about which language is better. Knowing programming language is not the most important thing for being a software developer. To be a really good developer you need to know OOP, design patterns, testing... and language is just a tool to make things happen. So back to my question. I have mixed experience in IT - 1 year as an IT support guy (Windows administration and support), around 2 years of experience in embedded programming (VB.Net 2005) and for the last 2 years I'm working with PHP/MySQL. I have worked with Magento web shop, assisted in some projects in Symfony, modified few Drupal sites. My main concerns are following: Do I continue to improve my skills in PHP e.g. to start learning some major PHP framework like Zend, Symfony maybe get some PHP certification. Or do I start learning .NET or Java. I'm more familiar to .NET so I'll probably choose it if choice falls between .NET and Java ( or you could convince me to choose Java :). Career-wise, I don't know what is the best choice. Learning new framework and language is more time consuming then improving my existing skills in PHP. But with .NET you have a lot of possibilities (Windows 7 Phone development, Silverlight, WPF) and possibly bigger chances to find better jobs. PHP jobs are less payed then .NET, at least, according to my researches (correct me if I'm wrong). But if I start now with .NET I'm just a beginner and my salary will be low. I need at least 2+ years of experience in some language to even try to find some job that is paying higher than $50-60k in NY. My main goal in next 2-3 years is to try to find a job in a $60-80k category. Don't get me wrong, I'm not just chasing money, but money is an important factor when you're trying to start a family. I'm 27 years old and I feel that there isn't a lot of room for wrong decisions regarding my career, so any advice will be very welcome. Update Thank you all for spending time to help me with my problem. All of the answers and comments have been very helpful. I have decided to stick with PHP but also to learn C# and Silverlight 4. We'll see where the life will take me.

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• How mod_cache working with "must-revalidate" and "max-age"?

  - by Dmitriy Sosunov

  Quick question before I will explain my flow: ?an mod_cache perform revalidate with if-none-match only if max-age is expired in case if it configured in reverse proxy mode? My goal is to reduce a number of revalidation requests to our the origin server. For instance: The first request goes to the origin server and then mod_cache save a response in to the cache according to header cache-control: max-age. And only when max-age is expired then mod_cache will revalidate with if-none-match. Currently, mod_cache revalidate each request, regardless that max-age is defined or not. My configuration of Apache 2.4.3 (Windows), on linux I see the same behavior that I will show below. ServerName proxy.lo ProxyRequests Off ProxyPreserveHost Off Header set Vary "Accept, Content-Type, Content-Encoding, Accept-Language" RequestHeader set X-Forwarded-Proto "http" # modify header for user agent's Header set Cache-Control "private, no-cache, no-store, no-transform" CacheQuickHandler off CacheDefaultExpire 300 # the origin server do not provide last-modified CacheIgnoreNoLastMod On CacheIgnoreCacheControl On # the origin server define cache-control: private, no-store only for user agents # Therefore, I would like ignore those headers on the proxy server. CacheStorePrivate On CacheStoreNoStore On CacheEnable disk / CacheRoot "C:/Apache.Cache" CacheDirLevels 5 CacheDirLength 4 CacheMinExpire 15 CacheDetailHeader on CacheHeader on KeepAlive Off ProxyPass / http://origin.lo/ ProxyPassReverse / http://origin.lo/ Also, I have turned on debug log level to see how mod_cache handles a content for caching: I provided this to show that mod_proxy always decides that a content isn't fresh. Why?I provided this to show that mod_proxy always decide that a content isn't fresh. Why? max-age was provided (see below). [Sun Nov 04 11:58:42.899890 2012] [cache:debug] [pid 6492:tid 1400] cache_storage.c(624): [client 192.168.1.100:63741] AH00698: cache: Key for entity /testpage?(null) is http://proxy.lo/testpage? [Sun Nov 04 11:58:42.899890 2012] [cache_disk:debug] [pid 6492:tid 1400] mod_cache_disk.c(569): [client 192.168.1.100:63741] AH00709: Recalled cached URL info header http://proxy.lo/testpage? [Sun Nov 04 11:58:42.899890 2012] [cache_disk:debug] [pid 6492:tid 1400] mod_cache_disk.c(865): [client 192.168.1.100:63741] AH00720: Recalled headers for URL http://proxy.lo/testpage? [Sun Nov 04 11:58:42.899890 2012] [cache:debug] [pid 6492:tid 1400] cache_storage.c(320): [client 192.168.1.100:63741] AH00695: Cached response for /testpage isn't fresh. Adding/replacing conditional request headers. [Sun Nov 04 11:58:42.899890 2012] [cache:debug] [pid 6492:tid 1400] mod_cache.c(414): [client 192.168.1.100:63741] AH00757: Adding CACHE_SAVE filter for /testpage [Sun Nov 04 11:58:42.899890 2012] [cache:debug] [pid 6492:tid 1400] mod_cache.c(448): [client 192.168.1.100:63741] AH00759: Adding CACHE_REMOVE_URL filter for /testpage [Sun Nov 04 11:58:42.899890 2012] [proxy:debug] [pid 6492:tid 1400] mod_proxy.c(1068): [client 192.168.1.100:63741] AH01143: Running scheme http handler (attempt 0) [Sun Nov 04 11:58:42.899890 2012] [proxy:debug] [pid 6492:tid 1400] proxy_util.c(1976): AH00942: HTTP: has acquired connection for (origin.lo) [Sun Nov 04 11:58:42.899890 2012] [proxy:debug] [pid 6492:tid 1400] proxy_util.c(2029): [client 192.168.1.100:63741] AH00944: connecting http://origin.lo/testpage to origin.lo:80 [Sun Nov 04 11:58:42.901890 2012] [proxy:debug] [pid 6492:tid 1400] proxy_util.c(2151): [client 192.168.1.100:63741] AH00947: connected /testpage to origin.lo:80 [Sun Nov 04 11:58:42.901890 2012] [proxy:debug] [pid 6492:tid 1400] proxy_util.c(2554): AH00962: HTTP: connection complete to 192.168.1.100:80 (origin.lo) [Sun Nov 04 11:58:42.903890 2012] [proxy:debug] [pid 6492:tid 1400] proxy_util.c(1991): AH00943: http: has released connection for (origin.lo) [Sun Nov 04 11:58:42.903890 2012] [headers:debug] [pid 6492:tid 1400] mod_headers.c(800): AH01502: headers: ap_headers_output_filter() [Sun Nov 04 11:58:42.903890 2012] [cache:debug] [pid 6492:tid 1400] mod_cache.c(1190): [client 192.168.1.100:63741] AH00769: cache: Caching url: /testpage [Sun Nov 04 11:58:42.903890 2012] [cache:debug] [pid 6492:tid 1400] mod_cache.c(1196): [client 192.168.1.100:63741] AH00770: cache: Removing CACHE_REMOVE_URL filter. [Sun Nov 04 11:58:42.904890 2012] [cache_disk:debug] [pid 6492:tid 1400] mod_cache_disk.c(1318): [client 192.168.1.100:63741] AH00737: commit_entity: Headers and body for URL http://proxy.lo/testpage? cached. The first request to the origin server without mod_proxy to http://origin.lo/ GET http://origin.lo/testpage HTTP/1.1 Host: origin.lo Connection: keep-alive User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.4 (KHTML, like Gecko) Chrome/22.0.1229.94 Safari/537.4 Accept: application/json Accept-Encoding: gzip,deflate,sdch Accept-Language: en-US,en;q=0.8 Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.3 The first response from the origin without mod_proxy HTTP/1.1 200 OK Cache-Control: must-revalidate, proxy-revalidate, max-age=30 Content-Type: application/json; charset=utf-8 ETag: "7cf651e2-176f-4ac1-808e-0e0c17cfd0a2" Server: Microsoft-IIS/7.5 X-AspNet-Version: 4.0.30319 X-Powered-By: ASP.NET Date: Sun, 04 Nov 2012 10:11:01 GMT Content-Length: 1877 So, I assumed that revalidation must be occur only in 30 seconds after the success response. Is't right? Let's check it:) Within 30 sec, the Google Chrome didn't perform any requests to the origin server to revalidate a request and has return the response from local cache. When max-age is expired, the Google Chrome perform a request to revalidate: GET http://origin.lo/testpage HTTP/1.1 Host: origin.lo Connection: keep-alive Cache-Control: max-age=0 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.4 (KHTML, like Gecko) Chrome/22.0.1229.94 Safari/537.4 Accept: application/xml If-None-Match: "7cf651e2-176f-4ac1-808e-0e0c17cfd0a2" Accept-Encoding: gzip,deflate,sdch Accept-Language: en-US,en;q=0.8 Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.3 and response: HTTP/1.1 304 Not Modified Cache-Control: must-revalidate, proxy-revalidate, max-age=30 ETag: "7cf651e2-176f-4ac1-808e-0e0c17cfd0a2" Server: Microsoft-IIS/7.5 X-AspNet-Version: 4.0.30319 X-Powered-By: ASP.NET Date: Sun, 04 Nov 2012 10:16:20 GMT As you can see, all works as expected. User agent revalidates request only when max-age is expired. Let's now try perform the folling flow though mod_proxy (see configuration above). The first request: GET http://proxy.lo/testpage HTTP/1.1 Host: proxy.lo Connection: keep-alive User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.4 (KHTML, like Gecko) Chrome/22.0.1229.94 Safari/537.4 Accept: application/json Accept-Encoding: gzip,deflate,sdch Accept-Language: en-US,en;q=0.8 Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.3 and the response was: HTTP/1.1 200 OK Date: Sun, 04 Nov 2012 10:23:36 GMT Server: Apache Cache-Control: private, no-cache, no-store, no-transform Content-Type: application/json; charset=utf-8 ETag: "7cf651e2-176f-4ac1-808e-0e0c17cfd0a2" Content-Length: 1932 Vary: Accept,Content-Type,Content-Encoding,Accept-Language X-Cache: MISS from proxy.lo X-Cache-Detail: "cache miss: attempting entity save" from proxy.lo Connection: close Ok, let's see to the disk cache and try to see how request and response was stored. (I cut binary data) http://proxy.lo/testpage? Cache-Control: private, no-cache, no-store, no-transform Content-Type: application/json; charset=utf-8 ETag: "7cf651e2-176f-4ac1-808e-0e0c17cfd0a2" Date: Sun, 04 Nov 2012 10:27:15 GMT Content-Length: 1932 Vary: Accept, Content-Type, Content-Encoding, Accept-Language Host: proxy.lo User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.4 (KHTML, like Gecko) Chrome/22.0.1229.94 Safari/537.4 Accept: application/json Accept-Encoding: gzip,deflate,sdch Accept-Language: en-US,en;q=0.8 Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.3 X-Forwarded-Proto: http Cache-Control: max-age=300, must-revalidate X-Forwarded-For: 192.168.1.100 X-Forwarded-Host: proxy.lo X-Forwarded-Server: origin.lo Ok, what we see? We see that the first request was performed with max-age=300 & must-revalidate Ok, looks good, as for me, lets perform the next call: GET http://proxy.lo/testpage HTTP/1.1 Host: proxy.lo Connection: keep-alive User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.4 (KHTML, like Gecko) Chrome/22.0.1229.94 Safari/537.4 Accept: application/json Accept-Encoding: gzip,deflate,sdch Accept-Language: en-US,en;q=0.8 Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.3 and the second response from mod_proxy: HTTP/1.1 200 OK Date: Sun, 04 Nov 2012 10:31:58 GMT Server: Apache Cache-Control: private, no-cache, no-store, no-transform ETag: "7cf651e2-176f-4ac1-808e-0e0c17cfd0a2" Content-Length: 1932 Vary: Accept,Content-Type,Content-Encoding,Accept-Language X-Cache: REVALIDATE from proxy.lo X-Cache-Detail: "conditional cache hit: entity refreshed" from proxy.lo Connection: close Content-Type: application/json; charset=utf-8 SO, MY QUESTION IS: WHY mod_proxy perform revalidation on each request regardless that max-age is defined? N.B. Apache 2.4.3 Thanks, I would be grateful for any help.

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