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  • Using PHP version 5.2 or 5.3 for commercial products?

    - by Ash
    I'm doing research on what version of PHP to use when creating commercial scripts that will be sold to the public. Although the available stats aren't great, PHP 5.3 shows a 18.5% adoption rate. I'd like to use Symfony to create these scripts and it requires 5.3.2 which shows an even lower adoption rate (roughly 13% of that 18.5% use less than 5.3.2). Would I be risking much by jumping straight to PHP 5.3.2+ or should I ignore the stats and plough ahead?

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  • How to publish your key used to sign deb packages so you will be able to use your repository from any machine?

    - by Sorin Sbarnea
    I am looking for a solution that would prevent me from seeing things like: W: GPG error: http://updates.example.com lenny Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 00AABBCCDDEE0011 The question applies for both Debian and Ubuntu. Isn't possible to publish the key somewhere where it can be automatically downloaded by apt-get based on it's signature? Note: I know that I can put my signature to an we server and use wget to get it and install it from there, still I am using for a better solution.

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  • Programmatically navigate to a new page

    - by [email protected]
    Did you know you can programmatically navigate to a new page via code?  Inside your bean method, you can simply use the NavigationDispatchHelper class to do the work for you. The invokePageNavigation method of NavigationDispatchHelper takes a String parameter that holds the value of the navigation rule to follow.   import oracle.adfnmc.util.NavigationDispatchHelper; public void MyBeanMethod() { /'/ Do stuff NavigationDispatchHelper.invokePageNavigation("patients"); }

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  • Java Spotlight Episode 104: Devoxx 4 Kids

    - by Roger Brinkley
    Stephan Jannsen talks about the new Devoxx 4 Kids that he launched this last weekend in Belgium. Right-click or Control-click to download this MP3 file. You can also subscribe to the Java Spotlight Podcast Feed to get the latest podcast automatically. If you use iTunes you can open iTunes and subscribe with this link:  Java Spotlight Podcast in iTunes. Show Notes News WebSocket JSR Early Draft (JSR 356) JAX-RS 2 Public Draft (JSR 339) JMS2, JAX-RS 2, WebSocket, JSON integrated in GlassFish 4 Promoted Builds Java EE 7 Revised Scope - Q2 2013 JavaOne Content Available for Free Please try Oracle's Java Uninstall Applet OpenJDK Community and Project Scorecard Experimental new utility to detect issues in javadoc comments PermGen Elimination project is promoting JDK bug migration milestone: JIRA now the system of record Project Jigsaw: On the next train New OpenJDK Projects: ThreeTen & Project Sumatra Events Oct 15-17, JAX London, London, United Kingdom Oct 20, Devoxx 4 Kids Français, Brussels, Belgium Oct 22-23, Freescale Technology Forum - Japan, Tokyo, Japan Oct 23-25, EclipseCon Europe, Ludwigsburg, Germany Oct 30-Nov 1, Arm TechCon, Santa Clara, United States of America Oct 31, JFall, Hart van Holland, Netherlands Nov 2-3, JMaghreb, Rabat, Morocco Nov 5-9, Øredev Developer Conference, Malmö, Sweden Nov 13-17, Devoxx, Antwerp, Belgium Nov 20-22, DOAG 2012, Nuremberg, Germany Dec 3-5, jDays, Göteborg, Sweden Dec 4-6, JavaOne Latin America, Sao Paolo, Brazil Feature InterviewStephan Janssen is a serial entrepreneur that has founded several successful organizations such as the Belgian Java User Group (BeJUG) in 1996, JCS Int. in 1998, JavaPolis in 2002 and now Parleys.com in 2006. He has been using Java since its early releases in 1995 with experience of developing and implementing real world Java solutions in the finance and manufacturing industries. Today Stephan is the CTO of the Java Competence Center at RealDolmen. He was selected by BEA Systems as the first European (independent) BEA Technical Director. He has also been recognized by the Server Side as one of the 54 Who is Who in Enterprise Java 2004. Sun has recognized in 2005 his efforts for the Java Community and has engaged him in the Java Champion project. He has spoken at numerous Java and JUG conferences around the world.Devoxx 4 KidsNew to Java Programming Center -- Young Developers What’s Cool "Here is the draft proposal to add a public Base64 utility class for JDK8." Default methods for jdk8: request for code review Raspberry Pi Model B now ships with 512MB of RAM JDuchess roadshow on the Island of Java. Nety and Mila from Meruvian.First week roadshowSecond week roadshowThird week part 1

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  • Partner Blog Series: PwC Perspectives - Looking at R2 for Customer Organizations

    - by Tanu Sood
    Welcome to the first of our partner blog series. November Mondays are all about PricewaterhouseCoopers' perespective on Identity and R2. In this series, we have identity management experts from PricewaterhouseCoopers (PwC) share their perspective on (and experiences with) the recent identity management release, Oracle Identity Management R2. The purpose of the series is to discuss real world identity use cases that helped shape the innovations in the recent R2 release and the implementation strategies that customers are employing today with expertise from PwC. Part 1: Looking at R2 for Customer Organizations In this inaugural post, we will discuss some of the new features of the R2 release of Oracle Identity Manager that some of our customer organizations are implementing today and the business rationale for those. Oracle's R2 Security portfolio represents a solid step forward for a platform that is already market-leading.  Prior to R2, Oracle was an industry titan in security with reliable products, expansive compatibility, and a large customer base.  Oracle has taken their identity platform to the next level in their latest version, R2.  The new features include a customizable UI, a request catalog, flexible security, and enhancements for its connectors, and more. Oracle customers will be impressed by the new Oracle Identity Manager (OIM) business-friendly UI.  Without question, Oracle has invested significant time in responding to customer feedback about making access requests and related activities easier for non-IT users.  The flexibility to add information to screens, hide fields that are not important to a particular customer, and adjust web themes to suit a company's preference make Oracle's Identity Manager stand out among its peers.  Customers can also expect to carry UI configurations forward with minimal migration effort to future versions of OIM.  Oracle's flexible UI will benefit many organizations looking for a customized feel with out-of-the-box configurations. Organizations looking to extend their services to end users will benefit significantly from new usability features like OIM’s ‘Catalog.’  Customers familiar with Oracle Identity Analytics' 'Glossary' feature will be able to relate to the concept.  It will enable Roles, Entitlements, Accounts, and Resources to be requested through the out-of-the-box UI.  This is an industry-changing feature as customers can make the process to request access easier than ever.  For additional ease of use, Oracle has introduced a shopping cart style request interface that further simplifies the experience for end users.  Common requests can be setup as profiles to save time.  All of this is combined with the approval workflow engine introduced in R1 that provides the flexibility customers need to meet their compliance requirements. Enhanced security was also on the list of features Oracle wanted to deliver to its customers.  The new end-user UI provides additional granular access controls.  Common Help Desk use cases can be implemented with ease by updating the application profiles.  Access can be rolled out so that administrators can only manage a certain department or organization.  Further, OIM can be more easily configured to select which fields can be read-only vs. updated.  Finally, this security model can be used to limit search results for roles and entitlements intended for a particular department.  Every customer has a different need for access and OIM now matches this need with a flexible security model. One of the important considerations when selecting an Identity Management platform is compatibility.  The number of supported platform connectors and how well it can integrate with non-supported platforms is a key consideration for selecting an identity suite.  Oracle has a long list of supported connectors.  When a customer has a requirement for a platform not on that list, Oracle has a solution too.  Oracle is introducing a simplified architecture called Identity Connector Framework (ICF), which holds the potential to simplify custom connectors.  Finally, Oracle has introduced a simplified process to profile new disconnected applications from the web browser.  This is a useful feature that enables administrators to profile applications quickly as well as empowering the application owner to fulfill requests from their web browser.  Support will still be available for connectors based on previous versions in R2. Oracle Identity Manager's new R2 version has delivered many new features customers have been asking for.  Oracle has matured their platform with R2, making it a truly distinctive platform among its peers. In our next post, expect a deep dive into use cases for a customer considering R2 as their new Enterprise identity solution. In the meantime, we look forward to hearing from you about the specific challenges you are facing and your experience in solving those. Meet the Writers Dharma Padala is a Director in the Advisory Security practice within PwC.  He has been implementing medium to large scale Identity Management solutions across multiple industries including utility, health care, entertainment, retail and financial sectors.   Dharma has 14 years of experience in delivering IT solutions out of which he has been implementing Identity Management solutions for the past 8 years. Scott MacDonald is a Director in the Advisory Security practice within PwC.  He has consulted for several clients across multiple industries including financial services, health care, automotive and retail.   Scott has 10 years of experience in delivering Identity Management solutions. John Misczak is a member of the Advisory Security practice within PwC.  He has experience implementing multiple Identity and Access Management solutions, specializing in Oracle Identity Manager and Business Process Engineering Language (BPEL). Jenny (Xiao) Zhang is a member of the Advisory Security practice within PwC.  She has consulted across multiple industries including financial services, entertainment and retail. Jenny has three years of experience in delivering IT solutions out of which she has been implementing Identity Management solutions for the past one and a half years. Praveen Krishna is a Manager in the Advisory  Security practice within PwC.  Over the last decade Praveen has helped clients plan, architect and implement Oracle identity solutions across diverse industries.  His experience includes delivering security across diverse topics like network, infrastructure, application and data where he brings a holistic point of view to problem solving.

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  • Conference on LinQ at Montreal's ETS

    - by Vincent Grondin
    Today I gave a presentation at Montreal's "Ecole de Technologies Supérieure" and I said I would put my presentation and the material itself online in here....  The audience was exclusively composed of teachers from colleges around Montreal.  There's the link to download the content : http://cid-bdf9cf467011e705.skydrive.live.com/self.aspx/.Public/LinQ%20at%20Montreal%5E4s%20ETS/LinQ.zip   I hope all attendees learned more on LinQ than they knew before!

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  • MiniMax function throws null pointer exception

    - by Sven
    I'm working on a school project, I have to build a tic tac toe game with the AI based on the MiniMax algorithm. The two player mode works like it should. I followed the code example on http://ethangunderson.com/blog/minimax-algorithm-in-c/. The only thing is that I get a NullPointer Exception when I run the code. And I can't wrap my finger around it. I placed a comment in the code where the exception is thrown. The recursive call is returning a null pointer, what is very strange because it can't.. When I place a breakpoint on the null return with the help of a if statement, then I see that there ARE still 2 to 3 empty places.. I probably overlooking something. Hope someone can tell me what I'm doing wrong. Here is the MiniMax code (the tic tac toe code is not important): /* * To change this template, choose Tools | Templates * and open the template in the editor. */ package MiniMax; import Game.Block; import Game.Board; import java.util.ArrayList; public class MiniMax { public static Place getBestMove(Board gameBoard, Block.TYPE player) { Place bestPlace = null; ArrayList<Place> emptyPlaces = gameBoard.getEmptyPlaces(); Board newBoard; //loop trough all the empty places for(Place emptyPlace : emptyPlaces) { newBoard = gameBoard.clone(); newBoard.setBlock(emptyPlace.getRow(), emptyPlace.getCell(), player); //no game won and still room to move if(newBoard.getWinner() == Block.TYPE.NONE && newBoard.getEmptyPlaces().size() > 0) { //is an node (has children) Place tempPlace = getBestMove(newBoard, invertPlayer(player)); //ERROR is thrown here! tempPlace is null. emptyPlace.setScore(tempPlace.getScore()); } else { //is an leaf if(newBoard.getWinner() == Block.TYPE.NONE) { emptyPlace.setScore(0); } else if(newBoard.getWinner() == Block.TYPE.X) { emptyPlace.setScore(-1); } else if(newBoard.getWinner() == Block.TYPE.O) { emptyPlace.setScore(1); } //if this move is better then our prev move, take it! if((bestPlace == null) || (player == Block.TYPE.X && emptyPlace.getScore() < bestPlace.getScore()) || (player == Block.TYPE.O && emptyPlace.getScore() > bestPlace.getScore())) { bestPlace = emptyPlace; } } } //This should never be null, but it does.. return bestPlace; } private static Block.TYPE invertPlayer(Block.TYPE player) { if(player == Block.TYPE.X) { return Block.TYPE.O; } return Block.TYPE.X; } }

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  • Is throwing an error in unpredictable subclass-specific circumstances a violation of LSP?

    - by Motti Strom
    Say, I wanted to create a Java List<String> (see spec) implementation that uses a complex subsystem, such as a database or file system, for its store so that it becomes a simple persistent collection rather than an basic in-memory one. (We're limiting it specifically to a List of Strings for the purposes of discussion, but it could extended to automatically de-/serialise any object, with some help. We can also provide persistent Sets, Maps and so on in this way too.) So here's a skeleton implementation: class DbBackedList implements List<String> { private DbBackedList() {} /** Returns a list, possibly non-empty */ public static getList() { return new DbBackedList(); } public String get(int index) { return Db.getTable().getRow(i).asString(); // may throw DbExceptions! } // add(String), add(int, String), etc. ... } My problem lies with the fact that the underlying DB API may encounter connection errors that are not specified in the List interface that it should throw. My problem is whether this violates Liskov's Substitution Principle (LSP). Bob Martin actually gives an example of a PersistentSet in his paper on LSP that violates LSP. The difference is that his newly-specified Exception there is determined by the inserted value and so is strengthening the precondition. In my case the connection/read error is unpredictable and due to external factors and so is not technically a new precondition, merely an error of circumstance, perhaps like OutOfMemoryError which can occur even when unspecified. In normal circumstances, the new Error/Exception might never be thrown. (The caller could catch if it is aware of the possibility, just as a memory-restricted Java program might specifically catch OOME.) Is this therefore a valid argument for throwing an extra error and can I still claim to be a valid java.util.List (or pick your SDK/language/collection in general) and not in violation of LSP? If this does indeed violate LSP and thus not practically usable, I have provided two less-palatable alternative solutions as answers that you can comment on, see below. Footnote: Use Cases In the simplest case, the goal is to provide a familiar interface for cases when (say) a database is just being used as a persistent list, and allow regular List operations such as search, subList and iteration. Another, more adventurous, use-case is as a slot-in replacement for libraries that work with basic Lists, e.g if we have a third-party task queue that usually works with a plain List: new TaskWorkQueue(new ArrayList<String>()).start() which is susceptible to losing all it's queue in event of a crash, if we just replace this with: new TaskWorkQueue(new DbBackedList()).start() we get a instant persistence and the ability to share the tasks amongst more than one machine. In either case, we could either handle connection/read exceptions that are thrown, perhaps retrying the connection/read first, or allow them to throw and crash the program (e.g. if we can't change the TaskWorkQueue code).

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  • Communities - The importance of exchange and discussion

    Communication with your environment is an essential part of everyone's life. And it doesn't matter whether you are actually living in a rural area in the middle of nowhere, within the pulsating heart of a big city, or in my case on a wonderful island in the Indian Ocean. The ability to exchange your thoughts, your experience and your worries with another person helps you to get different points of view and new ideas on how to resolve an issue you might be confronted with. Benefits of community work What happens to be common sense in your daily life, also applies to your work environment. Working in IT, or ICT as it is called in Mauritius, requires a lot of reading and learning. Not only during your lectures at the university but with your colleagues in a project assignment and hopefully with 'unknown' pals in the universe of online communities. At least I can say that I learned quite a lot from other developers code, their responses in various forums, their numerous blog articles, and while attending local user group meetings. When I started to work as a professional software developer (or engineer some may say) years ago I immediately checked the existence of communities on the programming language, the database technology and other vital information on software development in general. Luckily, it wasn't too difficult to find. My employer had a subscription of the monthly magazines and newsletters of a national organisation which also run the biggest forum in that area. Getting in touch with other developers and reading their common problems but also solutions was a huge benefit to my growth. Image courtesy of Michael Kappel (CC BY-NC 2.0) Active participation and regular contribution to this community gave me some nice advantages, too. Within three years I was listed as a conference speaker at the annual developer's conference and provided several sessions on different topics during consecutive years. Back in 2004, I took over the responsibility and management of the monthly meetings of a regional user group, and organised it for more than two years. Furthermore, I was invited to the newly-founded community program of Microsoft Germany (Community Leader/Insider Program - CLIP). My website on Active FoxPro Pages was nominated in the second batch of online communities. Due to my community work and providing advice to others, I had the honour to be awarded as Microsoft Most Valuable Professional (MVP) - Visual Developer for Visual FoxPro in the years 2006 and 2007. It was a great experience to meet with other like-minded people and I'm really grateful for that. Just in case, more details are listed in my Curriculum Vitae. But this all changed when I moved to Mauritius... Cyber island Mauritius? During the first months in Mauritius I was way too busy to think about community activities at all. First of all, there was the new company that had to be set up, the new staff had to be trained and of course the communication work-flows and so on with the project managers back in Germany had to be sorted out, too. Second, I had to get a grip of my private matters like getting the basics for my new household or exploring the neighbourhood, and last but not least I needed a break from the hectic and intensive work prior to my departure. As soon as the sea literally calmed down, I started to have conversations with my colleagues about communities and user groups. Sadly, it turned out that there were none, or at least no one was aware of any at that time. Oh oh, what did I do? Anyway, having this kind of background and very positive experience with off-line and on-line activities I decided for myself that some day I'm going to found a community in Mauritius for all kind of IT/ICT-related fields. The main focus might be on software development but not on a certain technology or methodology. It was clear to me that it should be an open infrastructure and anyone is welcome to join, to experience, to share and to contribute if they would like to. That was the idea at that time... Ok, fast-forward to recent events. At the end of October 2012 I was invited to an event called Open Days organised by Microsoft Indian Ocean Islands together with other local partners and resellers. There I got in touch with local Technical Evangelist Arnaud Meslier and we had a good conversation on communities during the breaks. Eventually, I left a good impression on him, as we are having chats on Facebook or Skype irregularly. Well, seeing that my personal and professional surroundings have been settled and running smooth, having that great exchange and contact with Microsoft IOI (again), and being really eager to re-animate my intentions from 2007, I recently founded a new community: Mauritius Software Craftsmanship Community - #MSCC It took me a while to settle down with the name but it was obvious that the community should not be attached to one single technology, like ie. .NET user group, Oracle developers, or Joomla friends (these are fictitious names). There are several other reasons why I came up with 'Craftsmanship' as the core topic of this community. The expression of 'engineering' didn't feel right with the fields covered. Software development in all kind of facets is a craft, and therefore demands a lot of practice but also guidance from more experienced developers. It also includes the process of designing, modelling and drafting the ideas. Has to deal with various types of tests and test methodologies, and of course should be focused on flexible and agile ways of acting. In order to meet and to excel a customer's request for a solution. Next, I was looking for an easy way to handle the organisation of events and meeting appointments. Using all kind of social media platforms like Google+, LinkedIn, Facebook, Xing, etc. I was never really confident about their features of event handling. More by chance I stumbled upon Meetup.com and in combination with the other entities (G+ Communities, FB Pages or in Groups) I am looking forward to advertise and manage all future activities here: Mauritius Software Craftsmanship Community This is a community for those who care and are proud of what they do. For those developers, regardless how experienced they are, who want to improve and master their craft. This is a community for those who believe that being average is just not good enough. I know, there are not many 'craftsmen' yet but it's a start... Let's see how it looks like by the end of the year. There are free smartphone apps for Android and iOS from Meetup.com that allow you to keep track of meetings and to stay informed on latest updates. And last but not least, there will be a Trello workspace to collect and share ideas and provide downloads of slides, etc. Sharing is caring! As mentioned, the #MSCC is present in various social media networks in order to cover as many people as possible here in Mauritius. Following is an overview of the current networks: Twitter - Latest updates and quickies Google+ - Community channel Facebook - Community Page LinkedIn - Community Group Trello - Collaboration workspace to share and develop ideas Hopefully, this covers the majority of computer-related people in Mauritius. Please spread the word about the #MSCC between your colleagues, your friends and other interested 'geeks'. Your future looks bright Running and participating in a user group or any kind of community usually provides quite a number of advantages for anyone. On the one side it is very joyful for me to organise appointments and get in touch with people that might be interested to present a little demo of their projects or their recent problems they had to tackle down, and on the other side there are lots of companies that have various support programs or sponsorships especially tailored for user groups. At the moment, I already have a couple of gimmicks that I would like to hand out in small contests or raffles during one of the upcoming meetings, and as said, companies provide all kind of goodies, books free of charge, or sometimes even licenses for communities. Meeting other software developers or IT guys also opens up your point of view on the local market and there might be interesting projects or job offers available, too. A community like the Mauritius Software Craftsmanship Community is great for freelancers, self-employed, students and of course employees. Meetings will be organised on a regular basis, and I'm open to all kind of suggestions from you. Please leave a comment here in blog or join the conversations in the above mentioned social networks. Let's get this community up and running, my fellow Mauritians!

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  • Google.org Crisis Response and the Google Maps APIs

    Google.org Crisis Response and the Google Maps APIs This week, Pete Giencke and Ka-Ping Yee of the Google Crisis Response Team join Paul Saxman to talk about the technologies and data they use for their mapping efforts, such as the Crisis Map and Google Public Alerts. Join us to learn how to use the Google Maps APIs to track hurricanes, monitor floods, and help affected users locate critical information such as shelters and evacuation routes in the aftermath of a disaster. From: GoogleDevelopers Views: 0 0 ratings Time: 00:00 More in Science & Technology

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  • La vulnérabilité de Java déjà exploitée depuis des serveurs russes, Oracle reste sur sa position

    Mise à jour du 15/04/10 La vulnérabilité de Java déjà exploitée Depuis des serveurs russes, Oracle reste sur sa position La faille de Java récemment mise à jour par un ingénieur de Google (lire ci-avant) serait déjà exploitée. Roger Thompson, chef chercheur chez AVG, a repéré des attaques depuis des serveurs russes utilisés par des sites qui ciblent le grand public (comme Songlyrics.com, qui propose les paroles de chansons de Lady Gaga, Rihanna, etc.). En arrivant sur ce site, un iFrame malicieux camouflé dans une publicité redirige l'utilisateur (sans que celui-ci ne s'en aperçoive) vers un serveur hébergeant l'exploit....

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  • StrongVPN on Ubuntu: Simple VPN Solution That Works

    <b>Linx Pro Magazine:</b> "Ask any knowledgeable mobile user, and she will tell you that the best way to securely access the Internet in public places is through a VPN (virtual private network) connection. So if you enjoy sipping coffee at a local cafe while checking email and browsing the Web, a secure VPN connection is a good solution..."

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  • Using an AGPL 3.0-licensed library for extra functionality in an iOS app

    - by Arnold Sakhnov
    I am building an iOS application, and I am planning to incorporate an AGPL 3.0-licensed library to it to provide some extra (non-essential) functionality. I’ve got a couple of questions regarding this: Do I understand it right that this still obliges me to publish the source of my app open? If yes, does it have to be open to the general public, or only to those who have downloaded the app? Does this allow me to distribute the app for a fee?

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  • Selectively Exposing Functionallity in .Net

    - by David V. Corbin
    Any developer should be aware of the principles of encapsulation, cross-tier isolation, and cross-functional separation of concerns. However, it seems the few take the time to consider the adage of "minimal yet complete"1 when developing the software. Consider the exposure of "business objects" to the user interface. Some common situations occur: Accessing a given element requires a compound set of calls that do not "make sense" to the User Interface. More information than absolutely required is exposed to the user interface It would be much cleaner if a custom interface was provided that exposed exactly (and only) the information that is required by the consumer. Achieving this using conventional techniques would require the creation (and maintenance!) of custom classes to filter and transpose the information into the ideal format. Determining the ROI on this approach can be very difficult to ascertain, and as a result it is often ignored completely. There is another approach, which is largely made practical by virtual of the Action and Func delegates. From a callers point of view, the following two samples can be used interchangeably:     interface ISomeInterface     {         void SampleMethod1(string param);         string SamepleMethod2(string param);     }       class ISomeInterface     {         public Action<string> SampleMethod1 {get; }         public Func<string,string> SamepleMethod2 {get; }     }   The capabilities this simple changes enable are significant (and remember it does not cange the syntax at the call site): The delegates can be initialized to directly call the proper method of any target class. The delegates can be dynamically updated based on the current state. The "interface" can NOT be cast to the concrete class (which often exposes more functionallity). This patterns By limiting the interface to the exact functionallity required, the reduced surface area will typically result in lower development, testing and maintenance costs. We are currently in the process of posting a project on CodePlex which illustrates this (and many other) techniques which have proven helpful in creating robust yet flexible solutions that are highly efficient2 and maintainable. This post will be updated as soon as the project is published. 1) Credit: Scott  Meyers, Effective C++, Addison-Wesley 1992 2) For those who read my previous post on performance it should be noted that the use of delegates is on the same order of magnitude (actually a tiny amount faster) as conventional interfaces.

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  • How do I restrict concurrent statistics gathering to a small set of tables from a single schema?

    - by Maria Colgan
    I got an interesting question from one of my colleagues in the performance team last week about how to restrict a concurrent statistics gather to a small subset of tables from one schema, rather than the entire schema. I thought I would share the solution we came up with because it was rather elegant, and took advantage of concurrent statistics gathering, incremental statistics, and the not so well known “obj_filter_list” parameter in DBMS_STATS.GATHER_SCHEMA_STATS procedure. You should note that the solution outline below with “obj_filter_list” still applies, even when concurrent statistics gathering and/or incremental statistics gathering is disabled. The reason my colleague had asked the question in the first place was because he wanted to enable incremental statistics for 5 large partitioned tables in one schema. The first time you gather statistics after you enable incremental statistics on a table, you have to gather statistics for all of the existing partitions so that a synopsis may be created for them. If the partitioned table in question is large and contains a lot of partition, this could take a considerable amount of time. Since my colleague only had the Exadata environment at his disposal overnight, he wanted to re-gather statistics on 5 partition tables as quickly as possible to ensure that it all finished before morning. Prior to Oracle Database 11g Release 2, the only way to do this would have been to write a script with an individual DBMS_STATS.GATHER_TABLE_STATS command for each partition, in each of the 5 tables, as well as another one to gather global statistics on the table. Then, run each script in a separate session and manually manage how many of this session could run concurrently. Since each table has over one thousand partitions that would definitely be a daunting task and would most likely keep my colleague up all night! In Oracle Database 11g Release 2 we can take advantage of concurrent statistics gathering, which enables us to gather statistics on multiple tables in a schema (or database), and multiple (sub)partitions within a table concurrently. By using concurrent statistics gathering we no longer have to run individual statistics gathering commands for each partition. Oracle will automatically create a statistics gathering job for each partition, and one for the global statistics on each partitioned table. With the use of concurrent statistics, our script can now be simplified to just five DBMS_STATS.GATHER_TABLE_STATS commands, one for each table. This approach would work just fine but we really wanted to get this down to just one command. So how can we do that? You may be wondering why we didn’t just use the DBMS_STATS.GATHER_SCHEMA_STATS procedure with the OPTION parameter set to ‘GATHER STALE’. Unfortunately the statistics on the 5 partitioned tables were not stale and enabling incremental statistics does not mark the existing statistics stale. Plus how would we limit the schema statistics gather to just the 5 partitioned tables? So we went to ask one of the statistics developers if there was an alternative way. The developer told us the advantage of the “obj_filter_list” parameter in DBMS_STATS.GATHER_SCHEMA_STATS procedure. The “obj_filter_list” parameter allows you to specify a list of objects that you want to gather statistics on within a schema or database. The parameter takes a collection of type DBMS_STATS.OBJECTTAB. Each entry in the collection has 5 feilds; the schema name or the object owner, the object type (i.e., ‘TABLE’ or ‘INDEX’), object name, partition name, and subpartition name. You don't have to specify all five fields for each entry. Empty fields in an entry are treated as if it is a wildcard field (similar to ‘*’ character in LIKE predicates). Each entry corresponds to one set of filter conditions on the objects. If you have more than one entry, an object is qualified for statistics gathering as long as it satisfies the filter conditions in one entry. You first must create the collection of objects, and then gather statistics for the specified collection. It’s probably easier to explain this with an example. I’m using the SH sample schema but needed a couple of additional partitioned table tables to get recreate my colleagues scenario of 5 partitioned tables. So I created SALES2, SALES3, and COSTS2 as copies of the SALES and COSTS table respectively (setup.sql). I also deleted statistics on all of the tables in the SH schema beforehand to more easily demonstrate our approach. Step 0. Delete the statistics on the tables in the SH schema. Step 1. Enable concurrent statistics gathering. Remember, this has to be done at the global level. Step 2. Enable incremental statistics for the 5 partitioned tables. Step 3. Create the DBMS_STATS.OBJECTTAB and pass it to the DBMS_STATS.GATHER_SCHEMA_STATS command. Here, you will notice that we defined two variables of DBMS_STATS.OBJECTTAB type. The first, filter_lst, will be used to pass the list of tables we want to gather statistics on, and will be the value passed to the obj_filter_list parameter. The second, obj_lst, will be used to capture the list of tables that have had statistics gathered on them by this command, and will be the value passed to the objlist parameter. In Oracle Database 11g Release 2, you need to specify the objlist parameter in order to get the obj_filter_list parameter to work correctly due to bug 14539274. Will also needed to define the number of objects we would supply in the obj_filter_list. In our case we ere specifying 5 tables (filter_lst.extend(5)). Finally, we need to specify the owner name and object name for each of the objects in the list. Once the list definition is complete we can issue the DBMS_STATS.GATHER_SCHEMA_STATS command. Step 4. Confirm statistics were gathered on the 5 partitioned tables. Here are a couple of other things to keep in mind when specifying the entries for the  obj_filter_list parameter. If a field in the entry is empty, i.e., null, it means there is no condition on this field. In the above example , suppose you remove the statement Obj_filter_lst(1).ownname := ‘SH’; You will get the same result since when you have specified gather_schema_stats so there is no need to further specify ownname in the obj_filter_lst. All of the names in the entry are normalized, i.e., uppercased if they are not double quoted. So in the above example, it is OK to use Obj_filter_lst(1).objname := ‘sales’;. However if you have a table called ‘MyTab’ instead of ‘MYTAB’, then you need to specify Obj_filter_lst(1).objname := ‘”MyTab”’; As I said before, although we have illustrated the usage of the obj_filter_list parameter for partitioned tables, with concurrent and incremental statistics gathering turned on, the obj_filter_list parameter is generally applicable to any gather_database_stats, gather_dictionary_stats and gather_schema_stats command. You can get a copy of the script I used to generate this post here. +Maria Colgan

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  • Emtel Knowledge Series - Q2/2014

    From Cyber Island to Smart Mauritius Cyber Island? Smart Mauritius? - What is Emtel talking about? "With the majority of the population living in urban environments today, the concept of "Smart Cities" has become an urgent necessity. "Smart Cities" refer to an urban transformation which, by using latest ICT technologies makes cities more efficient. Many Governments are setting out ambitious plans to build the cities of the future based on massive connectivity, high bandwidth communications, intelligent sensors and analysis of huge volumes of data. Various researches have shown four key enablers for smart city success - Government leadership, suitable technology infrastructure, solid public-private partnerships and engaged citizens. It is around these enabling factors that telecoms companies can play a vital role in assisting governments to deliver on the smart city vision." The Emtel Knowledge Series goes in compliance with Emtel's 25th anniversary celebrations throughout the year and the master of ceremony, Kim Andersen, mentioned that there will be more upcoming events on a quarterly base. As a representative of the Mauritius Software Craftsmanship Community (MSCC) there was absolutely no hesitation to join in again. Following my visit to the first Emtel Knowledge Series workshop back in February this year, it was great to have another opportunity to meet and exchange with technology experts. But quite frankly what is it with those buzz words... As far as I remember and how it was mentioned "Cyber Island" is an old initiative from around 2005/2006 which has been refreshed in 2010. It implies the empowerment of Information & Communication Technologies (ICT) as an essential factor of growth by the government here in Mauritius. Actually, the first promotional period of Cyber Island brought me here but that's another story. The venue and its own problems Like last time the event was organised and held at the Conference Hall at Cyber Tower I in Ebene. As I've been working there for some years, I know about the frustrating situation of finding a proper parking. So, does Smart Island include better solutions for the search of parking spaces? Maybe, let's see whether I will be able to answer that question at the end of the article. Anyway, after circling around the tower almost two times, I finally got a decent space to put the car, without risking to get a ticket or damage actually. International speakers and their experience Once again, Emtel did a great job to get international expertise onto the stage to share their experience and vision on this kind of embarkment. Personally, I really appreciated the fact they were speakers of global reach and could provide own-experience knowledge. Johan Gott spoke about the fundamental change that the Swedish government ignited in order to move their society and workers' environment away from heavy industry towards a knowledge-based approach. Additionally, we spoke about the effort and transformation of New York City into a greener and more efficient Smart City. Given modern technology he also advised that any kind of available Big Data should be opened to the general public - this openness would provide a playground for anyone to garner new ideas and most probably solid solutions of which no one else thought about before. Emtel Knowledge Series on moving from Cyber Island to Smart Mauritus Later during the afternoon that exact statement regarding openness to and transparency of government-owned Big Data has been emphasised again by the Danish speaker Kim Andersen and his former colleague Mika Jantunen from Finland. Mika continued to underline the important role of the government to provide a solid foundation for a knowledge-based society and mentioned that Finnish citizens have a constitutional right to broadband connectivity. Next to free higher (tertiary) education Finland already produced a good number of innovations, among them are: First country to grant voting rights to women Free higher education Constitutional right to broadband connectivity Nokia Linux Angry Birds Sauna and others...  General access to internet via broadband and/or mobile connectivity is surely a key factor towards Smart Cities, or better said Smart Mauritius given the area dimensions and size of population. CTO Paul Valette gave the audience a brief overview of the essential role that Emtel will have to move Mauritius forward towards a knowledge-based and innovation-driven environment for its citizen. What I have seen looks really promising and with recently published information that Mauritians have 127% of mobile capacity - meaning more than 1 mobile, smartphone or tablet per person - it will be crucial to have the right infrastructure for these connected devices. How would it be possible to achieve a knowledge-based society? YouTube to the rescue!Seriously, gaining more knowledge will require to have fast access to educational course material as explained by Dr Kaviraj Sukon, General Director of the Open University of Mauritius. According to him a good number of high-profile universities in the world have opened their course libraries to the general public, among them EDX, Coursera and Open University. Nowadays, you're actually able and enabled to learn for and earn a BSc or even MSc certification on your own pace - no need to attend classed on campus. It was really impressive to see the number of available hours - more than enough for a life-long learning experience! {loadposition content_adsense} Networking in the name of MSCC As briefly mentioned above I was about to combine two approaches for this workshop. Of course, getting latest information and updates on Emtel services available, especially for my business here on the west coast of the island, but also to meet and greet new people for the MSCC. And I think it was very positive on both sides. Let me quickly describe some of the key aspects that happened during the day: Met with Arnaud Meslier and Kellie, both Microsoft to swap latest information on IT events. Hereby, I got an invite to Microsoft Windows Phone 8.1 Dev Camp. Got in touch with Arvin Lockee, Emtel to check our options to meet with the data team, and seizing the opportunity to have a visiting tour at the Emtel Data Centre. Had a great chat with Avinash Meetoo, Knowledge 7, Kim Andersen and Mika Jantunen about the situation of teaching and learning in general and specifically in the private sector here in Mauritius. Additionally, a number of various other interesting chats... Once again, I'm catching up on a couple of business cards in order to provide more background information about the MSCC, and to create a better awareness of MSCC within the local IT businesses. There is more to come soon!  Resume of the day The number of attendees during this event has been doubled or even tripled this time. The whole organisation has been improved massively and the combination of presentation and summarizing panel discussions was better than during the previous workshop back in February. Overall, once again a well-organised workshop and I'm already looking forward to join the next workshop in Q3. Update End of July we finally managed to visit the Emtel Data Centre in Arsenal. It was an interesting opportunity for some of our MSCC members.

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  • What is the diffference between "data hiding" and "encapsulation"?

    - by john smith optional
    I'm reading "Java concurrency in practice" and there is said: "Fortunately, the same object-oriented techniques that help you write well-organized, maintainable classes - such as encapsulation and data hiding -can also help you crate thread-safe classes." The problem #1 - I never heard about data hiding and don't know what it is. The problem #2 - I always thought that encapsulation is using private vs public, and is actually the data hiding. Can you please explain what data hiding is and how it differs from encapsulation?

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  • Custom Music in Skyrim's Creation Kit?

    - by CptSupermrkt
    Can you bring in external music such as mp3s? If so, how? I didn't see anything about this in the wiki Bethesda released. Also how does this work with regards to the Steam Workshop? Don't imagine they would appreciate uploading copyrighted content. I don't particularly care about making a public mod, I just want to screw around privately and create dungeons/towns using music from some of my favorite games. Thanks.

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  • IrrKlang with Ogre

    - by Vinnie
    I'm trying to set up sound in my Ogre3D project. I have installed irrKlang 1.4.0 and added it's include and lib directories to my projects VC++ Include and Library directories, but I'm still getting a Linker error when I attempt to build. Any suggestions? (Error 4007 error LNK2019: unresolved external symbol "__declspec(dllimport) class irrklang::ISoundEngine * __cdecl irrklang::createIrrKlangDevice(enum irrklang::E_SOUND_OUTPUT_DRIVER,int,char const *,char const *)" (_imp?createIrrKlangDevice@irrklang@@YAPAVISoundEngine@1@W4E_SOUND_OUTPUT_DRIVER@1@HPBD1@Z) referenced in function "public: __thiscall SoundManager::SoundManager(void)" (??0SoundManager@@QAE@XZ)

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  • Adding complexity to remove duplicate code

    - by Phil
    I have several classes that all inherit from a generic base class. The base class contains a collection of several objects of type T. Each child class needs to be able to calculate interpolated values from the collection of objects, but since the child classes use different types, the calculation varies a tiny bit from class to class. So far I have copy/pasted my code from class to class and made minor modifications to each. But now I am trying to remove the duplicated code and replace it with one generic interpolation method in my base class. However that is proving to be very difficult, and all the solutions I have thought of seem way too complex. I am starting to think the DRY principle does not apply as much in this kind of situation, but that sounds like blasphemy. How much complexity is too much when trying to remove code duplication? EDIT: The best solution I can come up with goes something like this: Base Class: protected T GetInterpolated(int frame) { var index = SortedFrames.BinarySearch(frame); if (index >= 0) return Data[index]; index = ~index; if (index == 0) return Data[index]; if (index >= Data.Count) return Data[Data.Count - 1]; return GetInterpolatedItem(frame, Data[index - 1], Data[index]); } protected abstract T GetInterpolatedItem(int frame, T lower, T upper); Child class A: public IGpsCoordinate GetInterpolatedCoord(int frame) { ReadData(); return GetInterpolated(frame); } protected override IGpsCoordinate GetInterpolatedItem(int frame, IGpsCoordinate lower, IGpsCoordinate upper) { double ratio = GetInterpolationRatio(frame, lower.Frame, upper.Frame); var x = GetInterpolatedValue(lower.X, upper.X, ratio); var y = GetInterpolatedValue(lower.Y, upper.Y, ratio); var z = GetInterpolatedValue(lower.Z, upper.Z, ratio); return new GpsCoordinate(frame, x, y, z); } Child class B: public double GetMph(int frame) { ReadData(); return GetInterpolated(frame).MilesPerHour; } protected override ISpeed GetInterpolatedItem(int frame, ISpeed lower, ISpeed upper) { var ratio = GetInterpolationRatio(frame, lower.Frame, upper.Frame); var mph = GetInterpolatedValue(lower.MilesPerHour, upper.MilesPerHour, ratio); return new Speed(frame, mph); }

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  • Licensing issues with using code from samples coming with SDK

    - by Andrey
    Samples coming with SDK are intended to provide best practices. So logically it looks perfectly valid to take code from them. But usually samples come under licenses, for example a lot of samples from Microsoft are released under Microsoft Public License (MS-PL). Samples are usually published to provide best practices and common reusable code. But how can I use code from samples if they are under rather strict licenses?

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  • Gradle for NetBeans RCP

    - by Geertjan
    Start with the NetBeans Paint Application and do the following to build it via Gradle (i.e., no Gradle/NetBeans plugin is needed for the following steps), assuming you've set up Gradle. Do everything below in the Files or Favorites window, not in the Projects window. In the application directory "Paint Application". Create a file named "settings.gradle", with this content: include 'ColorChooser', 'Paint' Create another file in the same location, named "build.gradle", with this content: subprojects { apply plugin: "announce" apply plugin: "java" sourceSets { main { java { srcDir 'src' } resources { srcDir 'src' } } } } In the module directory "Paint". Create a file named "build.gradle", with this content: dependencies { compile fileTree("$rootDir/build/public-package-jars").matching { include '**/*.jar' } } task show << { configurations.compile.each { dep -> println "$dep ${dep.isFile()}" } } Note: The above is a temporary solution, as you can see, the expectation is that the JARs are in the 'build/public-packages-jars' folder, which assumes an Ant build has been done prior to the Gradle build. Now run 'gradle classes' in the "Paint Application" folder and everything will compile correctly. So, this is how the Paint Application now looks: Preferable to the second 'build.gradle' would be this, which uses the JARs found in the NetBeans Platform... netbeansHome = '/home/geertjan/netbeans-dev-201111110600' dependencies { compile files("$rootDir/ColorChooser/release/modules/ext/ColorChooser.jar") def projectXml = new XmlParser().parse("nbproject/project.xml") projectXml.configuration.data."module-dependencies".dependency."code-name-base".each { if (it.text().equals('org.openide.filesystems')) { def dep = "$netbeansHome/platform/core/"+it.text().replace('.','-')+'.jar' compile files(dep) } else if (it.text().equals('org.openide.util.lookup') || it.text().equals('org.openide.util')) { def dep = "$netbeansHome/platform/lib/"+it.text().replace('.','-')+'.jar' compile files(dep) } else { def dep = "$netbeansHome/platform/modules/"+it.text().replace('.','-')+'.jar' compile files(dep) } } } task show << { configurations.compile.each { dep -> println "$dep ${dep.isFile()}" } } However, when you run 'gradle classes' with the above, you get an error like this: geertjan@geertjan:~/NetBeansProjects/PaintApp1/Paint$ gradle classes :Paint:compileJava [ant:javac] Note: Attempting to workaround javac bug #6512707 [ant:javac] [ant:javac] [ant:javac] An annotation processor threw an uncaught exception. [ant:javac] Consult the following stack trace for details. [ant:javac] java.lang.NullPointerException [ant:javac] at com.sun.tools.javac.util.DefaultFileManager.getFileForOutput(DefaultFileManager.java:1058) No idea why the above happens, still trying to figure it out. Once the above works, we can start figuring out how to use the NetBeans Maven repo instead and then the user of the plugin will be able to select whether to use local JARs or JARs from the NetBeans Maven repo. Many thanks to Hans Dockter who put the above together with me today, via Skype!

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  • Not attending the LUGM mini-meetup - 05. Oct 2013

    Not attending a meeting of the LUGM can be fun, too. It's getting a bit of a habit that Ish is organising small gatherings, aka mini-meetups, of the Linux User Group Mauritius/Meta (LUGM) almost every Saturday. There they mainly discuss and talk about various elements of using Linux as ones main operating systems and the possibilities you are going to have. On top of course, some tips & tricks about mastering the command line and initial steps in scripting or even writing HTML. In general, sounds like a good portion of fun and great spirit of community. Unfortunately, I'm usually quite busy with private and family matters during the weekend and so I already signalised that I wouldn't be around. Well, at least not physically... But this Saturday a couple of things worked out faster than expected and so I was hanging out on my machine. I made virtual contact with one of Pawan's messages over on Facebook... And somehow that kicked off some kind of an online game fun on basic configuration of Apache HTTPd 2.2.x, PHP 5.x and how to improve the overall performance of a newly installed blog based on WordPress. Default configuration files Nitin's website finally came alive and despite the dark theme and the hidden Apple 'fanboy' advertisement I was more interested in the technical situation. As with any new installation there is usually quite some adjustment to be done. And Nitin's page was no exception. Unfortunately, out of the box installations of Apache httpd and PHP are too verbose and expose too much information under the hood. You might think that this isn't really a problem at all, well, think about it again after completely reading this article. First, I checked the HTTP response headers - using either Chrome Developer Tools or Firefox Web Developer extension - of Nitin's page and based on that I advised him to lower the noise levels a little bit. It's not really necessary that detailed information about web server software and scripting language has to be published in every response made. Quite a number of script kiddies and exploits actually check for version specifics prior to an attack. So, removing at least version details hardens the system a little bit. In particular, I'm talking about these response values: Server X-Powered-By How to achieve that? By tweaking the configuration files... Namely, we are going to look into the following ones: apache2.conf httpd.conf .htaccess php.ini The above list contains some additional files, I'm talking about in the next paragraphs. Anyway, those are the ones involved. Tweaking Apache Open your favourite text editor and start to modify the apache2.conf. Eventually, you might like to have a quick peak at the file to see whether it is necessary to adjust it or not. Following is a handy combination of commands to get an overview of your active directives: # sudo grep -v '#' /etc/apache2/apache2.conf | grep -v '^$' | less There you keep an eye on those two Apache directives: ServerSignature Off ServerTokens Prod If that's not the case, change them as highlighted above. In order to activate your modifications you have to restart Apache httpd server. On Debian and Ubuntu you might use apache2ctl for that, on other distributions you might have to use service or run the init-scripts again: # sudo apache2ctl configtestSyntax OK# sudo apache2ctl restart Refresh your website and check the HTTP response header. Tweaking PHP5 (a little bit) Next, check your php.ini file with the following statement: # sudo grep -v ';' /etc/php5/apache2/php.ini | grep -v '^$' | less And check the value of expose_php = Off Again, if it's not as highlighted, change it... Some more Apache love Okay, back to Apache it might also be interesting to improve the situation about browser caching and removing more obsolete information. When you run your website against the usual performance checks like Google Page Speed and Yahoo YSlow you might see those check points with bad grades on a standard, default configuration. Well, this can be done easily. Configure entity tags (ETags) ETags are only interesting when you run your websites on a farm of multiple web servers. Removing this data for your static resources is very simple in Apache. As we are going to deal with the HTTP response header information you have to ensure that Apache is capable to manipulate them. First, check your enabled modules: # sudo ls -al /etc/apache2/mods-enabled/ | grep headers And in case that the 'headers' module is not listed, you have to enable it from the available ones: # sudo a2enmod headers Second, check your httpd.conf file (in case it exists): # sudo grep -v '#' /etc/apache2/httpd.conf | grep -v '^$' | less In newer (better said fresh) installations you might have to create a new configuration file below your conf.d folder with your favourite text editor like so: # sudo nano /etc/apache2/conf.d/headers.conf Then, in order to tweak your HTTP responses either check for those lines or add them: Header unset ETagFileETag None In case that your file doesn't exist or those lines are missing, feel free to create/add them. Afterwards, check your Apache configuration syntax and restart your running instances as already shown above: # sudo apache2ctl configtestSyntax OK# sudo apache2ctl restart Add Expires headers To improve the loading performance of your website, you should take some care into the proper configuration of how to leverage the browser's ability to cache certain resources and files. This is done by adding an Expires: value to the HTTP response header. Generally speaking it is advised that you specify a near-future, read: 1 week or a little bit more, for your static content like JavaScript files or Cascading Style Sheets. One solution to adjust this is to put some instructions into the .htaccess file in the root folder of your web site. Of course, this could also be placed into a more generic location of your Apache installation but honestly, I'd like to keep this at the web site level. Following some adjustments I'm currently using on this blog site: # Turn on Expires and set default to 0ExpiresActive OnExpiresDefault A0 # Set up caching on media files for 1 year (forever?)<FilesMatch "\.(flv|ico|pdf|avi|mov|ppt|doc|mp3|wmv|wav)$">ExpiresDefault A29030400Header append Cache-Control "public"</FilesMatch> # Set up caching on media files for 1 week<FilesMatch "\.(js|css)$">ExpiresDefault A604800Header append Cache-Control "public"</FilesMatch> # Set up caching on media files for 31 days<FilesMatch "\.(gif|jpg|jpeg|png|swf)$">ExpiresDefault A2678400Header append Cache-Control "public"</FilesMatch> As we are editing the .htaccess files, it is not necessary to restart Apache. In case that your web site doesn't load anymore or you're experiencing an error while trying to restart your httpd, check that the 'expires' module is actually an enabled module: # ls -al /etc/apache2/mods-enabled/ | grep expires# sudo a2enmod expires Of course, the instructions above a re not feature complete but I hope that they might provide a better default configuration for your LAMP stack. Resume of the day Within a couple of hours, and while being occupied with an eLearning course on SQL Server 2012, I had some good fun in helping and assisting other LUGM members while they were some kilometers away at Bagatelle. According to other blog articles it seems that Nitin had quite some moments of desperation. Just for the records: At no time it was my intention to either kick his butt or pull a leg on him. Simply, providing some input based on the lessons I've learned over the last couple of years configuring Apache HTTPd and PHP. Check out the other blogs, too: LUGM mini-meetup... Epic! Superb Saturday Linux Meetup And last but not least, the man himself: The end of a new beginning Cheers, and happy community'ing! Updates Due to our weekly Code & Coffee sessions in the MSCC community, I had a chance to talk to Nitin directly and he showed me the problems directly on his machine. This led to update this article hence the paragraphs on enabling the modules 'headers' and 'expires'.

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  • Library to fake intermittent failures according to tester-defined policy?

    - by crosstalk
    I'm looking for a library that I can use to help mock a program component that works only intermittently - usually, it works fine, but sometimes it fails. For example, suppose I need to read data from a file, and my program has to avoid crashing or hanging when a read fails due to a disk head crash. I'd like to model that by having a mock data reader function that returns mock data 90% of the time, but hangs or returns garbage otherwise. Or, if I'm stress-testing my full program, I could turn on debugging code in my real data reader module to make it return real data 90% of the time and hang otherwise. Now, obviously, in this particular example I could just code up my mock manually to test against a random() routine. However, I was looking for a system that allows implementing any failure policy I want, including: Fail randomly 10% of the time Succeed 10 times, fail 4 times, repeat Fail semi-randomly, such that one failure tends to be followed by a burst of more failures Any policy the tester wants to define Furthermore, I'd like to be able to change the failure policy at runtime, using either code internal to the program under test, or external knobs or switches (though the latter can be implemented with the former). In pig-Java, I'd envision a FailureFaker interface like so: interface FailureFaker { /** Return true if and only if the mocked operation succeeded. Implementors should override this method with versions consistent with their failure policy. */ public boolean attempt(); } And each failure policy would be a class implementing FailureFaker; for example there would be a PatternFailureFaker that would succeed N times, then fail M times, then repeat, and a AlwaysFailFailureFaker that I'd use temporarily when I need to simulate, say, someone removing the external hard drive my data was on. The policy could then be used (and changed) in my mock object code like so: class MyMockComponent { FailureFaker faker; public void doSomething() { if (faker.attempt()) { // ... } else { throw new RuntimeException(); } } void setFailurePolicy (FailureFaker policy) { this.faker = policy; } } Now, this seems like something that would be part of a mocking library, so I wouldn't be surprised if it's been done before. (In fact, I got the idea from Steve Maguire's Writing Solid Code, where he discusses this exact idea on pages 228-231, saying that such facilities were common in Microsoft code of that early-90's era.) However, I'm only familiar with EasyMock and jMockit for Java, and neither AFAIK have this function, or something similar with different syntax. Hence, the question: Do such libraries as I've described above exist? If they do, where have you found them useful? If you haven't found them useful, why not?

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