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• Specific path to java class file when embedded into HTML; Help urgent

  - by Jeevanism

  This is a resonant post to one of my other query due to an error with Java applet embedded into CMS pages. well, I tell issue:- Problem:- I have a website using Concrete 5 CMS, in which I have a page that I have embedded a Java applet class. This applet should show the system information which this applet is working fine in simple single HTML pages. now whenever I access my plugin Test page which created in Concrete 5 CMS (this page I embedded this java applet), it shows a Java error. The error is says incompatible Magic Number. Observation:- After a lot of searching through various tech forums, I finally found that, the issue is happened because the browser cannot load Java class file. The class file path location is wrong. Here below I post the log of server access when I test in my local machine. 127.0.0.1 - - [20/Dec/2012:12:59:28 +0800] "GET /linuxhouse/index.php/techlab/java/testvm.class HTTP/1.1" 200 1896 "-" "Mozilla/4.0 (Linux 2.6.37.6-0.9-desktop) Java/1.6.0_29" 127.0.0.1 - - [20/Dec/2012:12:59:29 +0800] "GET /linuxhouse/index.php/techlab/java/testvm.class HTTP/1.1" 200 1896 "-" "Mozilla/4.0 (Linux 2.6.37.6-0.9-desktop) Java/1.6.0_29" <<<<<<<<<<<<<<<<<<<<< Clearly, the path to Java class file is wrong. But I have no idea how to specify exact path in an embedded code. Is this a CMS specific issue. I have disabled Pretty URL feature of CMS. But still I cannot find the solution. here the referred Page that shows the java error. http://www.linux-house.net/v3/techlab/plugin pls pls give some insight..URGENT SOS

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• Proper way to reassign pointers in c++

  - by user272689

  I want to make sure i have these basic ideas correct before moving on (I am coming from a Java/Python background). I have been searching the net, but haven't found a concrete answer to this question yet. When you reassign a pointer to a new object, do you have to call delete on the old object first to avoid a memory leak? My intuition is telling me yes, but i want a concrete answer before moving on. For example, let say you had a class that stored a pointer to a string class MyClass { private: std::string *str; public: MyClass (const std::string &_str) { str=new std::string(_str); } void ChangeString(const std::string &_str) { // I am wondering if this is correct? delete str; str = new std::string(_str) /* * or could you simply do it like: * str = _str; */ } .... In the ChangeString method, which would be correct? I think i am getting hung up on if you dont use the new keyword for the second way, it will still compile and run like you expected. Does this just overwrite the data that this pointer points to? Or does it do something else? Any advice would be greatly appricated :D

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• OpenNMS monitoring SAP

  - by HannesFostie

  I was wondering if anyone had any experience plugging SAP into their OpenNMS installation. Mostly looking for experiences, perhaps Nagios comparisons, or some more concrete information on what is being monitored and how you did it. Go into as much details as you like. I am currently in the process of evaluating both Nagios and OpenNMS and the possibilities with SAP might be the deciding factor here. Sadly, I didn't find a whole lot on google on the subject.

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• MediaWiki on MS Sql Server

  - by kdbolt70

  Hello all, I've been doing some digging on running mediawiki on sql server instead of mySQL, but haven't come across any concrete information. All of our servers are running SQL Server so I'd like to stick with that. I've tried Screwturn wiki, which is an ASP.NET wiki implementation using SQL Server, but I'm not terribly happy with the editing interface, and would really like to get MediaWiki up and running. Does anyone know if this is possible? Thanks!

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• Why there are three rounds of message exchanges for integrated windows authentication for IE

  - by user197658

  According to the result monitored by fiddler, there are totally 3 handshakes for integrated windows authentication for IE. GET /home - 401 Unauthorized WWW-Authenticate: Negotiate, NTLM GET /home Authorization: Negotiate UYTYGHGYKHKJPPP-=== - 401 Unauthorized WWW-Authenticate: Negotiate UYUGKJKJKJ+++766== Get /home Authorization: Negotiate HJGKJLJLJ+++=== - 200 OK WWW-Authenticate: Negotiate UHLKJKJKJJLK=== Who knows what concrete things are done for the three, especially the 2nd one. P.S. The network environment is work group mode, other than domain mode, and the server is a website hosted on my local PC. In other words, the client (IE) & the server are both in the same machine.

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• Hard Drives: Always on or spin up/down as needed?

  - by Terminal Frost

  The specific application is a NAS that hosts media content and is frequently accessed during the day. My NAS was probably cycling on and off around 5 times a day so I decided to not allow it to spin down. I'm thinking this will be better for the drive, but I am not sure. I am wondering, however, if there is any concrete information out there as to what causes more detrimental wear on a hard disk: Spinning 24/7 or cycling on and off as needed?

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• Why does Microsoft Windows' performance appear to degrade over time?

  - by Ben Aston

  Windows XP/2k3 and earlier (can't attest to Vista, but suspect it's the same) all appear to become more sluggish over time as applications are installed and uninstalled. This is not a scientifically tested observation, but more of a learned-through-experience piece of wisdom. (I've always suspected the registry as being behind the issue.) Does anyone have any concrete evidence of this degradation occurring, or it just an invalid perception of mine?

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• A dusty server room

  - by pauska

  Here's the story.. The owners of the building we lease office space from decided to do a renovation of the exterior. This involved in some pretty heavy work at the level where our server room is, including exchanging windows wich are fit inside a concrete wall. My red alert went off when I heard that they were going to do the same thing with our server room (yes, our server room has a window. We're a small shop with 3 racks. The window is secured with steel bars.) I explicity told the contractor that they need to put up a temporarily wall between our racks and the original wall - and to make sure that the temporary wall is 100 % air and water-tight. They promised to do so. The temporary wall has a small door in it, so that workers can go in/out through the day (through our server room, wich was the only option....). On several occasions I could find the small door half-way shut while working evenings/nights. I locked the door, and thought that they would hopefully get the point soon and keep the door shut. I even gave a electrician a mouthful when I saw that he didn't close the door properly. By this point - I bet that most of you get a picture of what happened. Yes, they probably left the door open while drilling in the concrete. I present you our 4 weeks old EMC VNX: I'll even put in a little bonus, here is the APC UPS one rack further away from the temporary wall. See the nice little landing strip from my finger? What should I do? The only thing that comes to mind is to either call all our suppliers (EMC, HP, Dell, Cisco) and get them to send technicians to check out all the gear in the server room, or get some kind of certified 3rd-party consulant to check all of it. Would you run production systems on this gear? How long? Edit: I should also note that our aircondition isn't exactly enterprise-grade, given the nature of our small room. It's just a single inverter, wich have failed one time before I started working here (failed inverters usually leads to water dripping out).

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• What are incentives (if any) to use WinRT instead of .Net?

  - by Ark-kun

  Let's compare WinRT with .Net .Net .Net is the 13+ years evolution of COM. Three main parts of .Net are execution environment, standard libraries and supported languages. CLR is the native-code execution environment based on COM .Net Framework has a big set of standard libraries (implemented using managed and native code) that can be used from all .Net languages. There are .Net classes that allow using OS APIs. WPF or Silverlight provide a XAML-based UI framework .Net can be used with C++, C#, Javascript, Python, Ruby, VB, LISP, Scheme and many other languages. C++/.Net is a variation of the C++ language that allows interaction with .Net objects. .Net supports inheritance, generics, operator and method overloading and many other features. .Net allows creating apps that run on Windows (XP, 7, 8 Pro (Desktop and Metro), RT, CE, etc), Mac OS, Linux (+ other *nix); iOS, Android, Windows Phone (7, 8); Internet Explorer, Chrome, Firefox; XBox 360, Playstation Suite; raw microprocessors. There is support for creating games (2D/3D) using any managed language or C++. Created by Developer Division WinRT WinRT is based on COM. Three main parts of WinRT are execution environment, standard libraries and supported languages. WinRT has a native-code execution environment based on COM WinRT has a set of standard libraries that more or less can be used from WinRT languages. There are WinRT classes that allow using OS APIs. Unnamed Silverlight clone provides a XAML-based UI framework WinRT can be used with C++, C#, Javascript, VB. C++/CX is a variation of the C++ language that allows interaction with WinRT objects. Custom WinRT components don't support inheritance (classes must be sealed), generics, operator overloading and many other features. WinRT allows creating apps that run on Windows 8 Pro and RT (Metro only); Windows Phone 8 (limited). There is support for creating games (2D/3D) using C++ only. Ordered by Windows Team I think that all the aspects except the last ones are very important for developers. On the other hand it seems that the most important aspect for Microsoft is the last one. So, given the above comparison of conceptually identical technologies, what are incentives (if any) to use WinRT instead of .Net?

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• Managing hosts and iptables in scalable architecture

  - by hakunin

  Let's say I have a load balancer in front of 3 app servers. Let's say I also have these services available at certain IPs: Postgres server Redis server ElasticSearch server Memcached server 1 Memcached server 2 Memcached server 3 So that's 6 nodes at 6 different IP addresses. Naturally, every one of my 3 app servers needs to talk to these 6 servers above. Then, to make it a bit funkier, I also have 3 worker servers. And each worker also talks to the above 6 servers, but thankfully workers and apps never need to talk to each other. Now's the kicker. Everything is on Digital Ocean VPS. What that means is: you have no private network, no private IPs. You only have separate, random IP address on each machine. You can't mask them or anything. So in order to build a secure environment I would have to configure some iptables. For example: Open app servers be accessed by load balancer server Open redis, ES, PG, and each memcached servers to be accessed by each app's IP and each worker's IP This means that every time I add an app or worker I have to also reconfigure iptables in those above 6 servers to welcome the new app or worker. Is there a way to simplify this type of setup? I was thinking — what if there was a gateway machine between apps/workers and the above 6 machines. This way all the interaction would always happen via the gateway server, and when I add a new app or worker I wouldn't need to teach the 6 servers to let it in. If I went this route, then I'd hope a small 512mb server could handle that perhaps, and there wouldn't be almost any overhead. Or would there? Please help with best way to handle this situation. I would appreciate an answer as concrete as possible. I don't think this is too specific, because this general architecture is very common, and Digital Ocean is becoming increasingly popular. A concrete solution here would be much appreciated by many.

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• Sharing a serial port between two processes

  - by peterrus

  As it is not possible to directly share a serial port between two processes using Linux, I am looking for another way to achieve this, I have heard about socat but could not find a concrete example of how to realize the following: Split one physical serial port (/dev/ttyUSB0) into two virtual ports, one for reading and one for writing, as one process only needs to send data, and one only needs to receive data. I can no modify the sending application unfortunately.

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• Design pattern for cost calculator app?

  - by Anders Svensson

  Hi, I have a problem that I’ve tried to get help for before, but I wasn’t able to solve it then, so I’m trying to simplify the problem now to see if I can get some more concrete help with this because it is driving me crazy… Basically, I have a working (more complex) version of this application, which is a project cost calculator. But because I am at the same time trying to learn to design my applications better, I would like some input on how I could improve this design. Basically the main thing I want is input on the conditionals that (here) appear repeated in two places. The suggestions I got before was to use the strategy pattern or factory pattern. I also know about the Martin Fowler book with the suggestion to Refactor conditional with polymorphism. I understand that principle in his simpler example. But how can I do either of these things here (if any would be suitable)? The way I see it, the calculation is dependent on a couple of conditions: 1. What kind of service is it, writing or analysis? 2. Is the project small, medium or large? (Please note that there may be other parameters as well, equally different, such as “are the products new or previously existing?” So such parameters should be possible to add, but I tried to keep the example simple with only two parameters to be able to get concrete help) So refactoring with polymorphism would imply creating a number of subclasses, which I already have for the first condition (type of service), and should I really create more subclasses for the second condition as well (size)? What would that become, AnalysisSmall, AnalysisMedium, AnalysisLarge, WritingSmall, etc…??? No, I know that’s not good, I just don’t see how to work with that pattern anyway else? I see the same problem basically for the suggestions of using the strategy pattern (and the factory pattern as I see it would just be a helper to achieve the polymorphism above). So please, if anyone has concrete suggestions as to how to design these classes the best way I would be really grateful! Please also consider whether I have chosen the objects correctly too, or if they need to be redesigned. (Responses like "you should consider the factory pattern" will obviously not be helpful... I've already been down that road and I'm stumped at precisely how in this case) Regards, Anders The code (very simplified, don’t mind the fact that I’m using strings instead of enums, not using a config file for data etc, that will be done as necessary in the real application once I get the hang of these design problems): public abstract class Service { protected Dictionary<string, int> _hours; protected const int SMALL = 2; protected const int MEDIUM = 8; public int NumberOfProducts { get; set; } public abstract int GetHours(); } public class Writing : Service { public Writing(int numberOfProducts) { NumberOfProducts = numberOfProducts; _hours = new Dictionary<string, int> { { "small", 125 }, { "medium", 100 }, { "large", 60 } }; } public override int GetHours() { if (NumberOfProducts <= SMALL) return _hours["small"] * NumberOfProducts; if (NumberOfProducts <= MEDIUM) return (_hours["small"] * SMALL) + (_hours["medium"] * (NumberOfProducts - SMALL)); return (_hours["small"] * SMALL) + (_hours["medium"] * (MEDIUM - SMALL)) + (_hours["large"] * (NumberOfProducts - MEDIUM)); } } public class Analysis : Service { public Analysis(int numberOfProducts) { NumberOfProducts = numberOfProducts; _hours = new Dictionary<string, int> { { "small", 56 }, { "medium", 104 }, { "large", 200 } }; } public override int GetHours() { if (NumberOfProducts <= SMALL) return _hours["small"]; if (NumberOfProducts <= MEDIUM) return _hours["medium"]; return _hours["large"]; } } public partial class Form1 : Form { public Form1() { InitializeComponent(); List<int> quantities = new List<int>(); for (int i = 0; i < 100; i++) { quantities.Add(i); } comboBoxNumberOfProducts.DataSource = quantities; } private void comboBoxNumberOfProducts_SelectedIndexChanged(object sender, EventArgs e) { Service writing = new Writing((int) comboBoxNumberOfProducts.SelectedItem); Service analysis = new Analysis((int) comboBoxNumberOfProducts.SelectedItem); labelWriterHours.Text = writing.GetHours().ToString(); labelAnalysisHours.Text = analysis.GetHours().ToString(); } }

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• SYSLINUX 4.07 EDD 2013-07-25 Copyright (C) 1994-2013 H. Peter Anvin et al [duplicate]

  - by Aniel Arias

  This question already has an answer here: Not booting from USB or CD (SYSLINUX Message) 10 answers this what is happening, i downloaded (ubuntu-gnome-14.04.1-desktop) and (elementaryos-unstable-amd64.20140810) to try out in my laptop and i have use (unetbootin-windows-608) and (Universal-USB-Installer-1.9.5.5) but i get this message every time i try to boot from the usb (SYSLINUX 4.07 EDD 2013-07-25 Copyright (C) 1994-2013 H. Peter Anvin et al) however i tried in an old desktop that i have and it works although the installer gets stuck on most of the time at the part of reading partitions/hard drives so please i really need help with this. note: i did installed os x long time ago and i broke windows installation then fix it following some online tutorials just for FYI thanks please can somebody help to fix this problem, i have been looking on google but haven't found anything in concrete. please help

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• Try and catch error trapping. why is it so significant

  - by oded

  sorry if it sounds dumb ' as i am i a process of learnning java i try to understand , why on earth i should "try" a method to catch errors. it looks to me like the concept is:- ' letting a process run assuming its not properly developed. should i always assume that a program based on classes and inheritance is bound for unexpected errors, which i should handle with such a heavy tools like try catch throw throws ? should all java programs be included withing try catch framework? Thanks Oded.

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• Best practise for Progress Bar in Python's PyGTK

  - by Matthew Walker

  I would like to get feedback on others' opinions of best practice for how to implement a progress bar in Python's PyGTK. The work that the progress bar was to represent was very significant computationally. Therefore, I wanted the work to be done in a separate process (thus giving the operating system the possibility to run it on a different core). I wanted to be able to start the work, and then continue to use the GUI for other tasks while waiting for the results. I have seen many people asking this question indirectly, but I have not seen any concrete expert advice. I hope that by asking this question we will see a community's combined expertise. I have read the FAQ and I hope that "Programmers" is the right place to ask.

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• 15 Oracle customers are 'Winners' at Progressive Mfgs 100 Awards

  - by [email protected]

  This year, 15 Oracle customers will receive awards at the Managing Automation's PM100 Event  for their outstanding accomplishments in a number of supply chain applications innovation categories. The event will be held at the Breakers Hotel in Palm Beach Fl from May 3-6, 2010. Award winners include: Arvin Meritor, Ball Aerospace, US Dept. of Treasury/Engraving, Doosan Infracore, Freescale Semi, Ingersoll-Rand, JDS Uniphase, L&L Products, Masco Builders, Mercury Marine Sanmina-SCI, Siemens Water TEch, US Concrete, VirTex Assy Services. Details of the event and Oracle's sponsorship can be found at: http://www.managingautomation.com/awards/ or contact Stephen Slade at [email protected]      

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• Book Review: Oracle ADF Real World Developer’s Guide

  - by Frank Nimphius

  Recently PACKT Publishing published "Oracle ADF Real World Developer’s Guide" by Jobinesh Purushothaman, a product manager in our team. Though already the sixth book dedicated to Oracle ADF, it has a lot of great information in it that none of the previous books covered, making it a safe buy even for those who own the other books published by Oracle Press (McGrwHill) and PACKT Publishing. More than the half of the "Oracle ADF Real World Developer’s Guide" book is dedicated to Oracle ADF Business Components in a depth and clarity that allows you to feel the expertise that Jobinesh gained in this area. If you enjoy Jobinesh blog (http://jobinesh.blogspot.co.uk/) about Oracle ADF, then, no matter what expert you are in Oracle ADF, this book makes you happy as it provides you with detail information you always wished to have. If you are new to Oracle ADF, then this book alone doesn't get you flying, but, if you have some Java background, accelerates your learning big, big, big times. Chapter 1 is an introduction to Oracle ADF and not only explains the layers but also how it compares to plain Java EE solutions (page 13). If you are new to Oracle JDeveloper and ADF, then at the end of this chapter you know how to start JDeveloper and begin your ADF development Chapter 2 starts with what Jobinesh really is good at: ADF Business Components. In this chapter you learn about the architecture ingredients of ADF Business Components: View Objects, View Links, Associations, Entities, Row Sets, Query Collections and Application Modules. This chapter also provides a introduction to ADFBC SDO services, as well as sequence diagrams for what happens when you execute queries or commit updates. Chapter 3 is dedicated to entity objects and  is one of many chapters in this book you will enjoy and never want to miss. Jobinesh explains the artifacts that make up an entity object, how to work with entities and resource bundles, and many advanced topics, including inheritance, change history tracking, custom properties, validation and cursor handling.  Chapter 4 - you guessed it - is all about View objects. Comparable to entities, you learn about the XM files and classes that make a view object, as well as how to define and work with queries. List-of-values, inheritance, polymorphism, bind variables and data filtering are interesting - and important topics that follow. Again the chapter provides helpful sequence diagrams for you to understand what happens internally within a view object. Chapter 5 focuses on advanced view object and entity object topics, like lifecycle callback methods and when you want to override them. This chapter is a good digest of Jobinesh's blog entries (which most ADF developers have in their bookmark list). Really worth reading ! Chapter 6 then is bout Application Modules. Beside of what application modules are, this chapter covers important topics like properties, passivation, activation, application module pooling, how and where to write custom logic. In addition you learn about the AM lifecycle and request sequence. Chapter 7 is about the ADF binding layer. If you are new to Oracle ADF and got lost in the more advanced ADF Business Components chapters, then this chapter is where you get back into the game. In very easy terms, Jobinesh explains what the ADF binding is, how it fits into the JSF request lifecycle and what are the metadata file involved. Chapter 8 then goes into building data bound web user interfaces. In this chapter you get the basics of JavaServer Faces (e.g. managed beans) and learn about the interaction between the JSF UI and the ADF binding layer. Later this chapter provides advanced solutions for working with tree components and list of values. Chapter 9 introduces bounded task flows and ADF controller. This is a chapter you want to read if you are new to ADF of have started. Experts don't find anything new here, which doesn't mean that it is not worth reading it (I for example, enjoyed the controller talk very much) Chapter 10 is an advanced coverage of bounded task flow and talks about contextual events  Chapter 11 is another highlight and explains error handling, trains, transactions and more. I can only recommend you read this chapter. I am aware of many documents that cover exception handling in Oracle ADF (and my Oracle Magazine article for January/February 2013 does the same), but none that covers it in such a great depth. Chapter 12 covers ADF best practices, which is a great round-up of all the tips provided in this book (without Jobinesh to repeat himself). Its all cool stuff that helps you with your ADF projects. In summary, "Oracle ADF Real World Developer’s Guide" by Jobinesh Purushothaman is a great book and addition for all Oracle ADF developers and those who want to become one. Frank

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• Can my ikmnet test results say something about career choice I should take?

  - by Nicke

  I took 2 tests via ikmnet and scored 70 % on SQL and 65 % on Java. While not bad, it can be improved. The subskills I need to improve according to the test are interfaces and inheritance, compilation and deployment, flow control, The java.lang package and "Java Program Construction" and these topics seems rather broad to me. Rather than just learning by programming, could you advice me to take a certification, follow a course or otherwise improve my skills? By the way, I enjoy python more than Java so should I market myself more of a python programmer or even a role that some companies search for which seems like a system developer with more technical writing where the title is system analysts (evaluating systems in cooperation with management rather than programming.) Thank you for any comment and/or answer.

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• Google I/O 2010 - SEO site advice from the experts

  Google I/O 2010 - SEO site advice from the experts Google I/O 2010 - SEO site advice from the experts Tech Talks Matt Cutts, Greg Grothaus, Evan Roseman A perfect opportunity to get your website reviewed by the experts in the Google Search Quality team. Attendees can get concrete search engine optimization (SEO) feedback on their own sites. We'll also answer real-life questions that affect developers when it comes to optimizing their websites for search. For all I/O 2010 sessions, please go to code.google.com From: GoogleDevelopers Views: 308 12 ratings Time: 01:00:38 More in Science & Technology

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• O&rsquo;Reilly E-Book of the Day 15/Aug/2014 - Advanced Quantitative Finance with C++

  - by TATWORTH

  Originally posted on: http://geekswithblogs.net/TATWORTH/archive/2014/08/15/orsquoreilly-e-book-of-the-day-15aug2014---advanced-quantitative-finance.aspxToday’s half-price book of the Day offer from O’Reilly at http://shop.oreilly.com/product/9781782167228.do?code=MSDEAL is Advanced Quantitative Finance with C++. “This book will introduce you to the key mathematical models used to price financial derivatives, as well as the implementation of main numerical models used to solve them. In particular, equity, currency, interest rates, and credit derivatives are discussed. In the first part of the book, the main mathematical models used in the world of financial derivatives are discussed. Next, the numerical methods used to solve the mathematical models are presented. Finally, both the mathematical models and the numerical methods are used to solve some concrete problems in equity, forex, interest rate, and credit derivatives.”

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• Writing C# Code Using SOLID Principles

  - by bipinjoshi

  Most of the modern programming languages including C# support objected oriented programming. Features such as encapsulation, inheritance, overloading and polymorphism are code level features. Using these features is just one part of the story. Equally important is to apply some object oriented design principles while writing your C# code. SOLID principles is a set of five such principles--namely Single Responsibility Principle, Open/Closed Principle, Liskov Substitution Principle, Interface Segregation Principle and Dependency Inversion Principle. Applying these time proven principles make your code structured, neat and easy to maintain. This article discusses SOLID principles and also illustrates how they can be applied to your C# code.http://www.binaryintellect.net/articles/7f857089-68f5-4d76-a3b7-57b898b6f4a8.aspx 

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• Getting Started with Prism (aka Composite Application Guidance for WPF and Silverlight)

  - by dotneteer

  Overview Prism is a framework from the Microsoft Patterns and Practice team that allow you to create WPF and Silverlight in a modular way. It is especially valuable for larger projects in which a large number of developers can develop in parallel. Prism achieves its goal by supplying several services: · Dependency Injection (DI) and Inversion of control (IoC): By using DI, Prism takes away the responsibility of instantiating and managing the life time of dependency objects from individual components to a container. Prism relies on containers to discover, manage and compose large number of objects. By varying the configuration, the container can also inject mock objects for unit testing. Out of the box, Prism supports Unity and MEF as container although it is possible to use other containers by subclassing the Bootstrapper class. · Modularity and Region: Prism supplies the framework to split application into modules from the application shell. Each module is a library project that contains both UI and code and is responsible to initialize itself when loaded by the shell. Each window can be further divided into regions. A region is a user control with associated model. · Model, view and view-model (MVVM) pattern: Prism promotes the user MVVM. The use of DI container makes it much easier to inject model into view. WPF already has excellent data binding and commanding mechanism. To be productive with Prism, it is important to understand WPF data binding and commanding well. · Event-aggregation: Prism promotes loosely coupled components. Prism discourages for components from different modules to communicate each other, thus leading to dependency. Instead, Prism supplies an event-aggregation mechanism that allows components to publish and subscribe events without knowing each other. Architecture In the following, I will go into a little more detail on the services provided by Prism. Bootstrapper In a typical WPF application, application start-up is controls by App.xaml and its code behind. The main window of the application is typically specified in the App.xaml file. In a Prism application, we start a bootstrapper in the App class and delegate the duty of main window to the bootstrapper. The bootstrapper will start a dependency-injection container so all future object instantiations are managed by the container. Out of box, Prism provides the UnityBootstrapper and MefUnityBootstrapper abstract classes. All application needs to either provide a concrete implementation of one of these bootstrappers, or alternatively, subclass the Bootstrapper class with another DI container. A concrete bootstrapper class must implement the CreateShell method. Its responsibility is to resolve and create the Shell object through the DI container to serve as the main window for the application. The other important method to override is ConfigureModuleCatalog. The bootstrapper can register modules for the application. In a more advance scenario, an application does not have to know all its modules at compile time. Modules can be discovered at run time. Readers to refer to one of the Open Modularity Quick Starts for more information. Modules Once modules are registered with or discovered by Prism, they are instantiated by the DI container and their Initialize method is called. The DI container can inject into a module a region registry that implements IRegionViewRegistry interface. The module, in its Initialize method, can then call RegisterViewWithRegion method of the registry to register its regions. Regions Regions, once registered, are managed by the RegionManager. The shell can then load regions either through the RegionManager.RegionName attached property or dynamically through code. When a view is created by the region manager, the DI container can inject view model and other services into the view. The view then has a reference to the view model through which it can interact with backend services. Service locator Although it is possible to inject services into dependent classes through a DI container, an alternative way is to use the ServiceLocator to retrieve a service on demard. Prism supplies a service locator implementation and it is possible to get an instance of the service by calling: ServiceLocator.Current.GetInstance<IServiceType>() Event aggregator Prism supplies an IEventAggregator interface and implementation that can be injected into any class that needs to communicate with each other in a loosely-coupled fashion. The event aggregator uses a publisher/subscriber model. A class can publishes an event by calling eventAggregator.GetEvent<EventType>().Publish(parameter) to raise an event. Other classes can subscribe the event by calling eventAggregator.GetEvent<EventType>().Subscribe(EventHandler, other options). Getting started The easiest way to get started with Prism is to go through the Prism Hands-On labs and look at the Hello World QuickStart. The Hello World QuickStart shows how bootstrapper, modules and region works. Next, I would recommend you to look at the Stock Trader Reference Implementation. It is a more in depth example that resemble we want to set up an application. Several other QuickStarts cover individual Prism services. Some scenarios, such as dynamic module discovery, are more advanced. Apart from the official prism document, you can get an overview by reading Glen Block’s MSDN Magazine article. I have found the best free training material is from the Boise Code Camp. To be effective with Prism, it is important to understands key concepts of WPF well first, such as the DependencyProperty system, data binding, resource, theme and ICommand. It is also important to know your DI container of choice well. I will try to explorer these subjects in depth in the future. Testimony Recently, I worked on a desktop WPF application using Prism. I had a wonderful experience with Prism. The Prism is flexible enough even in the presence of third party controls such as Telerik WPF controls. We have never encountered any significant obstacle.

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• What functionality does dynamic typing allow?

  - by Justin984

  I've been using python for a few days now and I think I understand the difference between dynamic and static typing. What I don't understand is under what circumstances it would be preferred. It is flexible and readable, but at the expense of more runtime checks and additional required unit testing. Aside from non-functional criteria like flexibility and readability, what reasons are there to choose dynamic typing? What can I do with dynamic typing that isn't possible otherwise? What specific code example can you think of that illustrates a concrete advantage of dynamic typing?

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• Does Ubuntu generally post timely security updates?

  - by Jo Liss

  Concrete issue: The Oneiric nginx package is at version 1.0.5-1, released in July 2011 according to the changelog. The recent memory-disclosure vulnerability (advisory page, CVE-2012-1180, DSA-2434-1) isn't fixed in 1.0.5-1. If I'm not misreading the Ubuntu CVE page, all Ubuntu versions seem to ship a vulnerable nginx. Is this true? If so: I though there was a security team at Canonical that's actively working on issues like this, so I expected to get a security update within a short timeframe (hours or days) through apt-get update. Is this expectation -- that keeping my packages up-to-date is enough to stop my server from having known vulnerabilities -- generally wrong? If so: What should I do to keep it secure? Reading the Ubuntu security notices wouldn't have helped in this case, as the nginx vulnerability was never posted there.

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• Microsoft Generation 4 Datacenter using ITPACs

  - by Eric Nelson

  Microsoft is continuing to make significant investments in Datacenter technology and is focused on solving issues such as long lead times, significant up-front costs and over capacity. Enter the world of modular Datacenters and ITPACs – IT Pre-Assembled Components. In simple terms – air handling and IT units which are pre-assembled (looking somewhat like a container) and then installed on concrete bases. Each unit can hold  between 400 and 2500 servers (which means many more virtual machines depending on your density) Kevin Timmons’, manager of the datacenter operations team, just posted a great post digging into the detail One Small Step for Microsoft’s Cloud, Another Big Step for Sustainability which includes a short video on how we build one of these ITPACs. You might also want to check out this video from the PDC:

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