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• Need help identifing what resources (eg. In MIT OpenCourseWare) can help me prepare for a test [closed]

  - by jiewmeng

  I am entering uni soon. I can sit for a placement test to see if I elegible for exemptions. The details are http://www.comp.nus.edu.sg/undergraduates/TestScope11_12.html Or CS2100 Computer Organisation (please click title) The objective of this module is to familiarise students with the fundamentals of computing devices. Through this module students will understand the basics of data representation, and how the various parts of a computer work, separately and with each other. This allows students to understand the issues in computing devices, and how these issues affect the implementation of solutions. Topics covered include data representation systems, combinational and sequential circuit design techniques, assembly language, processor execution cycles, pipelining, memory hierarchy and input/output systems. Recommended Textbooks Digital Design: Principles and Practices [DDPP] by John F. Wakerly, Prentice-Hall. ISBN 0-13-324500-4. Computer Organizations and Design (The hardware/software interface) by David A. Patterson and John L. Hennessy. CS2105 Introduction to Computer Networks (please click title) This course aims to provide a broad introduction to computer networks and some appreciations of network application programming. It covers a range of topics including basic data communication and computer network concepts, protocols, networked computing concepts and principles, network applications development and network security. The emphasis of teaching is on the working principles and application of computer networks. As an integral part of the course, tutorials and practical assignments enforcing learning will also be given. These assignments provide an early exposure in network application programming and they should be able to complete by using personal computers and school's network facilities. Topics included: An overview of computer networks and the Internet Basic data communications Application layer Transport layer Network layer and routing Link layer and local area networks Recommended Textbook James F. Kurose & Keith W. Ross, Computer networking: A top-down approach featuring internet, Addison Wesley, 2001 I am wondering what resources eg. MIT OpenCourseWare or other universities resources are available to help he perpare for these particular modubles. I am thinking does the Networking one look like CCNA? The computer oragization. Its like electronics, assembly etc? I learnt some electronics in Poly but looking at the sample papers, uni looks very different... I have about 1 month to prepare if I want any chance of exempting from these modules :) any help?

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• Taking the Plunge - or Dipping Your Toe - into the Fluffy IAM Cloud by Paul Dhanjal (Simeio Solutions)

  - by Greg Jensen

  In our last three posts, we’ve examined the revolution that’s occurring today in identity and access management (IAM). We looked at the business drivers behind the growth of cloud-based IAM, the shortcomings of the old, last-century IAM models, and the new opportunities that federation, identity hubs and other new cloud capabilities can provide by changing the way you interact with everyone who does business with you. In this, our final post in the series, we’ll cover the key things you, the enterprise architect, should keep in mind when considering moving IAM to the cloud. Invariably, what starts the consideration process is a burning business need: a compliance requirement, security vulnerability or belt-tightening edict. Many on the business side view IAM as the “silver bullet” – and for good reason. You can almost always devise a solution using some aspect of IAM. The most critical question to ask first when using IAM to address the business need is, simply: is my solution complete? Typically, “business” is not focused on the big picture. Understandably, they’re focused instead on the need at hand: Can we be HIPAA compliant in 6 months? Can we tighten our new hire, employee transfer and termination processes? What can we do to prevent another password breach? Can we reduce our service center costs by the end of next quarter? The business may not be focused on the complete set of services offered by IAM but rather a single aspect or two. But it is the job – indeed the duty – of the enterprise architect to ensure that all aspects are being met. It’s like remodeling a house but failing to consider the impact on the foundation, the furnace or the zoning or setback requirements. While the homeowners may not be thinking of such things, the architect, of course, must. At Simeio Solutions, the way we ensure that all aspects are being taken into account – to expose any gaps or weaknesses – is to assess our client’s IAM capabilities against a five-step maturity model ranging from “ad hoc” to “optimized.” The model we use is similar to Capability Maturity Model Integration (CMMI) developed by the Software Engineering Institute (SEI) at Carnegie Mellon University. It’s based upon some simple criteria, which can provide a visual representation of how well our clients fair when evaluated against four core categories: ·         Program Governance ·         Access Management (e.g., Single Sign-On) ·         Identity and Access Governance (e.g., Identity Intelligence) ·         Enterprise Security (e.g., DLP and SIEM) Often our clients believe they have a solution with all the bases covered, but the model exposes the gaps or weaknesses. The gaps are ideal opportunities for the cloud to enter into the conversation. The complete process is straightforward: 1.    Look at the big picture, not just the immediate need – what is our roadmap and how does this solution fit? 2.    Determine where you stand with respect to the four core areas – what are the gaps? 3.    Decide how to cover the gaps – what role can the cloud play? Returning to our home remodeling analogy, at some point, if gaps or weaknesses are discovered when evaluating the complete impact of the proposed remodel – if the existing foundation wouldn’t support the new addition, for example – the owners need to decide if it’s time to move to a new house instead of trying to remodel the old one. However, with IAM it’s not an either-or proposition – i.e., either move to the cloud or fix the existing infrastructure. It’s possible to use new cloud technologies just to cover the gaps. Many of our clients start their migration to the cloud this way, dipping in their toe instead of taking the plunge all at once. Because our cloud services offering is based on the Oracle Identity and Access Management Suite, we can offer a tremendous amount of flexibility in this regard. The Oracle platform is not a collection of point solutions, but rather a complete, integrated, best-of-breed suite. Yet it’s not an all-or-nothing proposition. You can choose just the features and capabilities you need using a pay-as-you-go model, incrementally turning on and off services as needed. Better still, all the other capabilities are there, at the ready, whenever you need them. Spooling up these cloud-only services takes just a fraction of the time it would take a typical organization to deploy internally. SLAs in the cloud may be higher than on premise, too. And by using a suite of software that’s complete and integrated, you can dramatically lower cost and complexity. If your in-house solution cannot be migrated to the cloud, you might consider using hardware appliances such as Simeio’s Cloud Interceptor to extend your enterprise out into the network. You might also consider using Expert Managed Services. Cost is usually the key factor – not just development costs but also operational sustainment costs. Talent or resourcing issues often come into play when thinking about sustaining a program. Expert Managed Services such as those we offer at Simeio can address those concerns head on. In a cloud offering, identity and access services lend to the new paradigms described in my previous posts. Most importantly, it allows us all to focus on what we're meant to do – provide value, lower costs and increase security to our respective organizations. It’s that magic “silver bullet” that business knew you had all along. If you’d like to talk more, you can find us at simeiosolutions.com.

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• C# Dev - I've tried Lisps, but I don't get it.

  - by Jonathan Mitchem

  After a few months of learning about and playing with lisps, both CL and a bit of Clojure, I'm still not seeing a compelling reason to write anything in it instead of C#. I would really like some compelling reasons, or for someone to point out that I'm missing something really big. The strengths of a Lisp (per my research): Compact, expressive notation - More so than C#, yes... but I seem to be able to express those ideas in C# too. Implicit support for functional programming - C# with LINQ extension methods: mapcar = .Select( lambda ) mapcan = .Select( lambda ).Aggregate( (a,b) = a.Union(b) ) car/first = .First() cdr/rest = .Skip(1) .... etc. Lambda and higher-order function support - C# has this, and the syntax is arguably simpler: "(lambda (x) ( body ))" versus "x = ( body )" "#(" with "%", "%1", "%2" is nice in Clojure Method dispatch separated from the objects - C# has this through extension methods Multimethod dispatch - C# does not have this natively, but I could implement it as a function call in a few hours Code is Data (and Macros) - Maybe I haven't "gotten" macros, but I haven't seen a single example where the idea of a macro couldn't be implemented as a function; it doesn't change the "language", but I'm not sure that's a strength DSLs - Can only do it through function composition... but it works Untyped "exploratory" programming - for structs/classes, C#'s autoproperties and "object" work quite well, and you can easily escalate into stronger typing as you go along Runs on non-Windows hardware - Yeah, so? Outside of college, I've only known one person who doesn't run Windows at home, or at least a VM of Windows on *nix/Mac. (Then again, maybe this is more important than I thought and I've just been brainwashed...) The REPL for bottom-up design - Ok, I admit this is really really nice, and I miss it in C#. Things I'm missing in a Lisp (due to a mix of C#, .NET, Visual Studio, Resharper): Namespaces. Even with static methods, I like to tie them to a "class" to categorize their context (Clojure seems to have this, CL doesn't seem to.) Great compile and design-time support the type system allows me to determine "correctness" of the datastructures I pass around anything misspelled is underlined realtime; I don't have to wait until runtime to know code improvements (such as using an FP approach instead of an imperative one) are autosuggested GUI development tools: WinForms and WPF (I know Clojure has access to the Java GUI libraries, but they're entirely foreign to me.) GUI Debugging tools: breakpoints, step-in, step-over, value inspectors (text, xml, custom), watches, debug-by-thread, conditional breakpoints, call-stack window with the ability to jump to the code at any level in the stack (To be fair, my stint with Emacs+Slime seemed to provide some of this, but I'm partial to the VS GUI-driven approach) I really like the hype surrounding Lisps and I gave it a chance. But is there anything I can do in a Lisp that I can't do as well in C#? It might be a bit more verbose in C#, but I also have autocomplete. What am I missing? Why should I use Clojure/CL?

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• Can't boot Ubuntu 12.10 graphics problem

  - by Frantumn

  I can't boot since installing Ubuntu 12.10 When I try to run Ubuntu My computer never gets to the Ubuntu screen with the loading dots. I tried to run in recovery mode with safe graphics (failsafex) When I do this a message pops up saying "the system is running in low graphics mode", If I click okay I am asked what would I like to do and am given four options. I tried running low graphics for one session and then a message appears with a progress bar and says standby one minute while the display restarts. The progress bar never moves and if I click okay the whole process just restarts. I Don't know what to do from here I can't get into the OS. I'm not sure whether the problem is related to compatibility with my laptop monitor or my graphic card nvidia360m I had to install using a safe graphics mode. To learn about how I installed see this link. This link also has information on my computer hardware. Can't install Ubuntu since 10.10 ----UPDATE--- I was able to get into a desktop environment By installing Nvidia-current however it is messy. I have a screen and I am able to see my desktop however there is no unity bar and none of the keyboard controls work. I can right click and create a folder on the desktop and then I can see inside that folder in a traditional browser window. There is still no top menu or unity bar. When I boot normally I don't get into the desktop environment and I get this message in tty 'GPU lockup switching to software FBCON' Okay, I've played around with tips the pages from comments. I've been able to consistantly get into a safemode desktop environment using the xorg & nouveau drivers. I've tried switching between the 5 different options in the Additional Drivers tab in Software Sources. The nVidia (proprietary, tested) driver gets beyond the GPU lockup on a normal boot and actually gets into a Desktop. The issue is then that there is no Unity bar, or top screen menu bar and the resolution is very low. I've tried switching to the (prop, tested) driver and then reinstalling Unity and Ubuntu-Desktop but that didn't work either.

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• Seven Accounting Changes for 2010

  - by Theresa Hickman

  I read a very interesting article called Seven Accounting Changes That Will Affect Your 2010 Annual Report from SmartPros that nicely summarized how 2010 annual financial statements will be impacted.  Here’s a Reader’s Digest version of the changes: 1.  Changes to revenue recognition if you sell bundled products with multiple deliverables: Old Rule: You needed to objectively establish the “fair value” of each bundled item. So if you sold a dishwasher plus installation and could not establish the fair value of the installation, you might have to delay recognizing revenue of the dishwasher days or weeks later until it was installed. New Rule (ASU 2009-13): “Objective” proof of each service or good is no longer required; you can simply estimate the selling price of the installation and warranty. So the dishwasher vendor can recognize the dishwasher revenue immediately at the point of sale without waiting a few weeks for the installation. Then they can recognize the estimated value of the installation after it is complete. 2.  Changes to revenue recognition for devices with embedded software: Old Rule: Hardware devices with embedded software, such as the iPhone, had to follow stringent software revrec rules. This forced Apple to recognize iPhone revenues over two years, the period of time that software updates were provided. New Rule (ASU 2009-14): Software revrec rules no longer apply to these devices with embedded software; these devices can now follow ASU 2009-13. This allows vendors, such as Apple, to recognize revenue sooner. 3.  Fair value disclosures: Companies (both public and private) now need to spend extra time gathering, summarizing, and disclosing information about items measured at fair value, such as significant transfers in and out of Level 1(quoted market price), Level 2 (valuation based on observable markets), and Level 3 (valuations based on internal information). 4.  Consolidation of variable interest entities (a.k.a special purpose entities): Consolidation rules for variable interest entities now require a qualitative, not quantitative, analysis to determine the primary beneficiary. Instead of simply looking at the percentage of voting interests, the primary beneficiary could have less than the majority interests as long as it has the power to direct the activities and absorb any losses.  5.  XBRL: Starting in June 2011, all U.S. public companies are required to file financial statements to the SEC using XBRL. Note: Oracle supports XBRL reporting. 6.  Non-GAAP financial disclosures: Companies that report non-GAAP measures of performance, such as EBITDA in SEC filings, have more flexibility.  The new interpretations can be found here: http://www.sec.gov/divisions/corpfin/guidance/nongaapinterp.htm.  7.  Loss contingencies disclosures: Companies should expect additional scrutiny of their loss disclosures, such as those from litigation losses, in their annual financial statements. The SEC wants more disclosures about loss contingencies sooner instead of after the cases are settled.

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• iOS Support with Windows Azure Mobile Services – now with Push Notifications

  - by ScottGu

  A few weeks ago I posted about a number of improvements to Windows Azure Mobile Services. One of these was the addition of an Objective-C client SDK that allows iOS developers to easily use Mobile Services for data and authentication.  Today I'm excited to announce a number of improvement to our iOS SDK and, most significantly, our new support for Push Notifications via APNS (Apple Push Notification Services).  This makes it incredibly easy to fire push notifications to your iOS users from Windows Azure Mobile Service scripts. Push Notifications via APNS We've provided two complete tutorials that take you step-by-step through the provisioning and setup process to enable your Windows Azure Mobile Service application with APNS (Apple Push Notification Services), including all of the steps required to configure your application for push in the Apple iOS provisioning portal: Getting started with Push Notifications - iOS Push notifications to users by using Mobile Services - iOS Once you've configured your application in the Apple iOS provisioning portal and uploaded the APNS push certificate to the Apple provisioning portal, it's just a matter of uploading your APNS push certificate to Mobile Services using the Windows Azure admin portal: Clicking the “upload” within the “Push” tab of your Mobile Service allows you to browse your local file-system and locate/upload your exported certificate.  As part of this you can also select whether you want to use the sandbox (dev) or production (prod) Apple service: Now, the code to send a push notification to your clients from within a Windows Azure Mobile Service is as easy as the code below: push.apns.send(deviceToken, {      alert: 'Toast: A new Mobile Services task.',      sound: 'default' }); This will cause Windows Azure Mobile Services to connect to APNS (Apple Push Notification Service) and send a notification to the iOS device you specified via the deviceToken: Check out our reference documentation for full details on how to use the new Windows Azure Mobile Services apns object to send your push notifications. Feedback Scripts An important part of working with any PNS (Push Notification Service) is handling feedback for expired device tokens and channels. This typically happens when your application is uninstalled from a particular device and can no longer receive your notifications. With Windows Notification Services you get an instant response from the HTTP server.  Apple’s Notification Services works in a slightly different way and provides an additional endpoint you can connect to poll for a list of expired tokens. As with all of the capabilities we integrate with Mobile Services, our goal is to allow developers to focus more on building their app and less on building infrastructure to support their ideas. Therefore we knew we had to provide a simple way for developers to integrate feedback from APNS on a regular basis.  This week’s update now includes a new screen in the portal that allows you to optionally provide a script to process your APNS feedback – and it will be executed by Mobile Services on an ongoing basis: This script is invoked periodically while your service is active. To poll the feedback endpoint you can simply call the apns object's getFeedback method from within this script: push.apns.getFeedback({       success: function(results) {           // results is an array of objects with a deviceToken and time properties      } }); This returns you a list of invalid tokens that can now be removed from your database. iOS Client SDK improvements Over the last month we've continued to work with a number of iOS advisors to make improvements to our Objective-C SDK. The SDK is being developed under an open source license (Apache 2.0) and is available on github. Many of the improvements are behind the scenes to improve performance and memory usage. However, one of the biggest improvements to our iOS Client API is the addition of an even easier login method.  Below is the Objective-C code you can now write to invoke it: [client loginWithProvider:@"twitter"                     onController:self                        animated:YES                      completion:^(MSUser *user, NSError *error) {      // if no error, you are now logged in via twitter }]; This code will automatically present and dismiss our login view controller as a modal dialog on the specified controller.  This does all the hard work for you and makes login via Twitter, Google, Facebook and Microsoft Account identities just a single line of code. My colleague Josh just posted a short video demonstrating these new features which I'd recommend checking out: Summary The above features are all now live in production and are available to use immediately.  If you don’t already have a Windows Azure account, you can sign-up for a free trial and start using Mobile Services today. Visit the Windows Azure Mobile Developer Center to learn more about how to build apps with Mobile Services. Hope this helps, Scott P.S. In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu

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• Why Executives Need Enterprise Project Portfolio Management: 3 Key Considerations to Drive Value Across the Organization

  - by Melissa Centurio Lopes

  Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Cambria","serif";} By: Guy Barlow, Oracle Primavera Industry Strategy Director Over the last few years there has been a tremendous shift – some would say tectonic in nature – that has brought project management to the forefront of executive attention. Many factors have been driving this growing awareness, most notably, the global financial crisis, heightened regulatory environments and a need to more effectively operationalize corporate strategy. Executives in India are no exception. In fact, given the phenomenal rate of progress of the country, top of mind for all executives (whether in finance, operations, IT, etc.) is the need to build capacity, ramp-up production and ensure that the right resources are in place to capture growth opportunities. This applies across all industries from asset-intensive – like oil & gas, utilities and mining – to traditional manufacturing and the public sector, including services-based sectors such as the financial, telecom and life sciences segments are also part of the mix. However, compounding matters is a complex, interplay between projects – big and small, complex and simple – as companies expand and grow both domestically and internationally. So, having a standardized, enterprise wide solution for project portfolio management is natural. Failing to do so is akin to having two ERP systems, one to manage “large” invoices and one to manage “small” invoices. It makes no sense and provides no enterprise wide visibility. Therefore, it is imperative for executives to understand the full range of their business commitments, the benefit to the company, current performance and associated course corrections if needed. Irrespective of industry and regardless of the use case (e.g., building a power plant, launching a new financial service or developing a new automobile) company leaders need to approach the value of enterprise project portfolio management via 3 critical areas: Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Cambria","serif";} 1. Greater Financial Discipline – Improve financial rigor and results through better governance and control is an imperative given today’s financial uncertainty and greater investment scrutiny. For example, as India plans a US$1 trillion investment in the country’s infrastructure how do companies ensure costs are managed? How do you control cash flow? Can you easily report this to stakeholders? 2. Improved Operational Excellence – Increase efficiency and reduce costs through robust collaboration and integration. Upwards of 66% of cost variances are driven by poor supplier collaboration. As you execute initiatives do you have visibility into the performance of your supply base? How are they integrated into the broader program plan? 3. Enhanced Risk Mitigation – Manage and react to uncertainty through improved transparency and contingency planning. What happens if you’re faced with a skills shortage? How do you plan and account for geo-political or weather related events? In summary, projects are not just the delivery of a product or service to a customer inside a predetermined schedule; they often form a contractual and even moral obligation to shareholders and stakeholders alike. Hence the intimate connection between executives and projects, with the latter providing executives with the platform to demonstrate that their organization has the capabilities and competencies needed to meet and, whenever possible, exceed their customer commitments. Effectively developing and operationalizing corporate strategy is the hallmark of successful executives and enterprise project and portfolio management allows them to achieve this goal. Article was first published for Manage India, an e-newsletter, PMI India.

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• What's about Java?

  - by Silviu Turuga

  What is Java? In very short words, Java is a programming language that let you make an application that can be run on different operating systems, no matter we are talking about Windows, Mac OS, Linux or even embedded devices, such as RaspberryPi. When you compile a Java program, instead of getting a binary output as you get on other programming languages, you'll get a Java intermediate code, called Java bytecode. This is interpreted at run time, by a virtual machine that is specifically for the hardware and operating system you are using. What Java do i need? There are 5 major versions of Java: Java SE(Standard Edition) - this is what I'll use on most of my tutorials. Most of the examples will run on Java 6, but for others you'll need Java 7. Java EE (Enterprise Edition) - used for enterprise development Java ME (Micro Edition) - for running Java on mobile and different embedded devices such as PDAs, TV set-top boxes, printers, etc. Java Embedded - for some embedded devices such as Raspberry Pi, where the resources are limited JavaFX - to develop rich content User Interfaces. This is also something that will use a lot. More detailed information can be found on Oracle's website If you just want to run java applications you'll need the JRE (Java Runtime Environment) installed. If you want to program and create new applications, then you'll need the JDK (Java Development Kit).  How to check if Java is already installed? From command line, if you are on Windows, or from Terminal on Mac enter the following: java -version You should get something like this, if you have java installed on your system: java version "1.6.0_37" Java(TM) SE Runtime Environment (build 1.6.0_37-b06-434-11M3909) Java HotSpot(TM) 64-Bit Server VM (build 20.12-b01-434, mixed mode) Note: your current Java version might be different from mine. More information https://www.java.com/en/download/faq/whatis_java.xml http://en.wikipedia.org/wiki/Java_(programming_language) Next steps Install Java SDK Chose an IDE. I recommend NetBeans as it is very easy to use and also let you quickly create the GUI of your application Alternatives are Eclipse, Komodo Edit (for Mac), etc. There are plenty of solutions both free or paid. Resources on web Oracle Tutorials - lot of tutorials and useful resources JavaRanch - forum about java

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• My co-worker has not been doing such a good job for the past decade. What do I do? [closed]

  - by stijn

  Possible Duplicate: How do I approach a coworker about his or her code quality? I started working with him almost a decade ago and back then I had never really programmed before, being a young hardware engineer. Right now however I have made quite some progress in all areas being part of software design and i am much, much more skilled than my co-worker who is 15 years older and has been programming more than twice as long. He is super nice and definitely smart enough, but lately his lack of skill and performance are starting to drag me down because we're more and more working on the same codebase. And soon we are going to do a quite ambitious start from scratch creating a whole new hard/software system. I feel it is time to address all issues now, but i do not know how to start. Here are some of the things that I would like to see him improve on: no consistent usage of style, spaces nor tabs (eg if(something ) a =b ) adds newlines around pieces of code to make it easier to read, then commits those with messages like 'no changes made' overall commit messages are useless and so are most of the comments, if there are any (eg 'remove solves for bug Rik' if Rik reported a bug). There is no function/class documentation. lots of spelling errors, in both English and native language, which sometimes are mixed 6/7/8 level deep deep nesting is no exception, a lot of functions start with one level already like if(ptr!=Null){ even when ptr is the result of allocation via new in the constructor numerous source files have over 10k lines of those lines, a major part is simply a result of copy-pasting functionality instead of using a function. This includes copying comments so we end up with 50 occurrences of var=NULL; //TODO TEST this!!!!!!! another part is hundreds of lines of dead code knows what versioning does, yet comments out old code and places new code underneath it when making changes coding skills are below par, especially for the type of rather high precision applications we do. Yet somehow, after a lot of trying and testing, stuff starts to work. But then breaks again some time later because every change casues a waterfall effect. violates every single item in the C++ FAQ lite, practices every bad practice I can think of still doesn't know how to properly use the debugger, but spends hours inspecting messy logfiles in notepad on a tiny laptop screen. Does not make any adjustments to the settings of the software he uses. Never uses keyboard shortcuts. does not seem to progress or learn new things at all. Work rather slow, mostly due to the lack of planning and incorrect usage of tools. How does one deal with this? For starters, how do I make him aware of all these problems? Should I tell the staff about it? And the next step, how to get him to learn new things and adopt another way of working?

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• High CPU load for 1:30 minutes when mounting ext4-raid partition

  - by sirion

  I have a raid 5 (software) with 5x2TB drives. I encrypted the raid with cryptsetup and put an ext4-partition on top. In the beginning opening and mounting the raid took less than 10 seconds, now (for a few weeks) mounting alone takes 1:30 minutes and the cpu stays around 93% the whole time: The output of "time sudo mount /dev/mapper/8000 /media/8000" is: real 1m31.952s user 0m0.008s sys 1m25.229s At the same time only one line is added to /var/log/syslog: kernel: [ 2240.921381] EXT4-fs (dm-1): mounted filesystem with ordered data mode. Opts: (null) My Ubuntu-version is "12.04.1 LTS" and no updates are pending. I checked the partition with fsck, but it says that all is ok. The "cryptsetup luksOpen" command only takes a few seconds. I also tried changing the raid-bitmap (as it was suggested in some forum) but it did not change the behaviour. sudo mdadm --grow /dev/md0 -b internal and sudo mdadm --grow /dev/md0 -b none I had the idea that it might be the hardware being slow, but a read test with "sudo hdparm -t /dev/md0" spit out values between 62 and 159 MB/sec: Timing buffered disk reads: 382 MB in 3.00 seconds = 127.14 MB/sec Timing buffered disk reads: 482 MB in 3.02 seconds = 159.62 MB/sec Timing buffered disk reads: 190 MB in 3.03 seconds = 62.65 MB/sec Timing buffered disk reads: 474 MB in 3.02 seconds = 157.12 MB/sec Although I think it is strange that the read rate jumps by more than 100% - could that mean something? The speed test when reading from the mapped (decrypted) device shows similar behavior, although it is of course much slower. "sudo hdparm -t /dev/mapper/8000": Timing buffered disk reads: 56 MB in 3.02 seconds = 18.54 MB/sec Timing buffered disk reads: 122 MB in 3.09 seconds = 39.43 MB/sec Timing buffered disk reads: 134 MB in 3.02 seconds = 44.35 MB/sec The output of a verbose mount "mount -vvv /dev/mapper/8000 /media/8000" does not help much: mount: fstab path: "/etc/fstab" mount: mtab path: "/etc/mtab" mount: lock path: "/etc/mtab~" mount: temp path: "/etc/mtab.tmp" mount: UID: 0 mount: eUID: 0 mount: spec: "/dev/mapper/8000" mount: node: "/media/8000" mount: types: "(null)" mount: opts: "(null)" mount: you didn't specify a filesystem type for /dev/mapper/8000 I will try type ext4 mount: mount(2) syscall: source: "/dev/mapper/8000", target: "/media/8000", filesystemtype: "ext4", mountflags: -1058209792, data: (null) Any idea where I could find additional information on why mounting takes so long, or what additional tests I could run?

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• How granular should a command be in a CQ[R]S model?

  - by Aaronaught

  I'm considering a project to migrate part of our WCF-based SOA over to a service bus model (probably nServiceBus) and using some basic pub-sub to achieve Command-Query Separation. I'm not new to SOA, or even to service bus models, but I confess that until recently my concept of "separation" was limited to run-of-the-mill database mirroring and replication. Still, I'm attracted to the idea because it seems to provide all the benefits of an eventually-consistent system while sidestepping many of the obvious drawbacks (most notably the lack of proper transactional support). I've read a lot on the subject from Udi Dahan who is basically the guru on ESB architectures (at least in the Microsoft world), but one thing he says really puzzles me: As we get larger entities with more fields on them, we also get more actors working with those same entities, and the higher the likelihood that something will touch some attribute of them at any given time, increasing the number of concurrency conflicts. [...] A core element of CQRS is rethinking the design of the user interface to enable us to capture our users’ intent such that making a customer preferred is a different unit of work for the user than indicating that the customer has moved or that they’ve gotten married. Using an Excel-like UI for data changes doesn’t capture intent, as we saw above. -- Udi Dahan, Clarified CQRS From the perspective described in the quotation, it's hard to argue with that logic. But it seems to go against the grain with respect to SOAs. An SOA (and really services in general) are supposed to deal with coarse-grained messages so as to minimize network chatter - among many other benefits. I realize that network chatter is less of an issue when you've got highly-distributed systems with good message queuing and none of the baggage of RPC, but it doesn't seem wise to dismiss the issue entirely. Udi almost seems to be saying that every attribute change (i.e. field update) ought to be its own command, which is hard to imagine in the context of one user potentially updating hundreds or thousands of combined entities and attributes as it often is with a traditional web service. One batch update in SQL Server may take a fraction of a second given a good highly-parameterized query, table-valued parameter or bulk insert to a staging table; processing all of these updates one at a time is slow, slow, slow, and OLTP database hardware is the most expensive of all to scale up/out. Is there some way to reconcile these competing concerns? Am I thinking about it the wrong way? Does this problem have a well-known solution in the CQS/ESB world? If not, then how does one decide what the "right level" of granularity in a Command should be? Is there some "standard" one can use as a starting point - sort of like 3NF in databases - and only deviate when careful profiling suggests a potentially significant performance benefit? Or is this possibly one of those things that, despite several strong opinions being expressed by various experts, is really just a matter of opinion?

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• Ubuntu doesn't "see" external USB Hard Disk

  - by Mina Michael

  It's NTFS. It's USB2. I'm using Ubuntu 13.04. It works perfectly fine on Windows (which excludes cable and hardware problems). I have two Ubuntu computers and it's not detected on either. It's about 500 GB. Edits: Following the first link, I input sudo lsusb in a terminal; before and after connecting the HDD. The difference was Bus 001 Device 012: ID 14cd:6116 Super Top M6116 SATA Bridge. There it is! ("sata bridge" used to appear in a windows notification when I plugged in the HDD in!). ...This means that Ubuntu detects it but is it not mounting it? I tried this: sudo mount /dev/sdb1 /mnt But gives this: mount: special device /dev/sdb1 does not exist I also tried: sudo mount /dev/sdc1 /mnt but it stays with no output forever. I left it in background for about 30 min.s. sudo fdisk -l gives out this: Disk /dev/sda: 160.0 GB, 160041885696 bytes 255 heads, 63 sectors/track, 19457 cylinders, total 312581808 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0xa42d04a3 Device Boot Start End Blocks Id System /dev/sda1 63 80324 40131 de Dell Utility /dev/sda2 * 80325 102481919 51200797+ 7 HPFS/NTFS/exFAT /dev/sda3 263874558 312580095 24352769 5 Extended /dev/sda4 102481920 263872511 80695296 7 HPFS/NTFS/exFAT /dev/sda5 263874560 310505471 23315456 83 Linux /dev/sda6 310507520 312580095 1036288 82 Linux swap / Solaris Partition table entries are not in disk order Disk /dev/sdc: 500.1 GB, 500107862016 bytes 255 heads, 63 sectors/track, 60801 cylinders, total 976773168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x5822aaea Device Boot Start End Blocks Id System /dev/sdc1 2048 976769023 488383488 7 HPFS/NTFS/exFAT The part below "Partition table entries are not in disk order" takes about 5 minutes to appear. The outputs of ls /dev/ | grep sd before and after connecting the HDD: before: sda sda1 sda2 sda3 sda4 sda5 sda6 ,after: sda sda1 sda2 sda3 sda4 sda5 sda6 sdd sdd1 The second output has the lines sdd and sdd1 different from the first one. IT SHOWED THE FILES!! The command sudo mount /dev/sdd1 /mnt worked after I typed in sudo fdisk -l!!! Thanks a million!! :) :)

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• Reading the tea leaves from Windows Azure support

  - by jamiet

  A few idle thoughts… Three months ago I had an issue regarding Windows Azure where I was unable to login to the management portal. At the time I contacted Azure support, the issue was soon resolved and I thought no more about it. Until today that is when I received an email from Azure support providing a detailed analysis of the root cause, the fix and moreover precise details about when and where things occurred. The email itself is interesting and I have included the entirety of it below. A few things were interesting to me: The level of detail and the diligence in investigating and reporting the issue I found really rather impressive. They even outline the number of users that were affected (127 in case you can’t be bothered reading). Compare this to the quite pathetic support that another division within Microsoft, Skype, provided to Greg Low recently: Skype support and dead parrot sketches   This line: “Windows Azure performed a planned change from using the Microsoft account service (formerly Windows Live ID) to the Azure Active Directory (AAD) as its primary authentication mechanism on August 24th. This change was made to enable future innovation in the area of authentication – particularly for organizationally owned identities, identity federation, stronger authentication methods and compliance certification. ” I also found to be particularly interesting. I have long thought that one of the reasons Microsoft has proved to be such a money-making machine in the enterprise is because they provide the infrastructure and then upsell on top of that – and nothing is more infrastructural than Active Directory. It has struck me of late that they are trying to make the same play of late in the cloud by tying all their services into Azure Active Directory and here we see a clear indication of that by making AAD the authentication mechanism for anyone using Windows Azure. I get the feeling that we’re going to hear much much more about AAD in the future; isn’t it about time we could log on to SQL Azure Windows Azure SQL Database without resorting to SQL authentication, for example? And why do Microsoft have two identity providers – Microsoft Account (aka Windows Live ID) and AAD – isn’t it about time those things were combined? As I said, just some idle thoughts. Below is the transcript of the email if you are interested. @Jamiet  This is regarding the support request <redacted> where in you were not able to login into the windows azure management portal with live id. We are providing you with the summary, root cause analysis and information about permanent fix: Incident Title: You were unable to access Windows Azure Portal after Microsoft Account to Azure Active Directory account Migration. Service Impacted: Management Portal Incident Start Date and Time: 8/24/2012 4:30:00 PM Date and Time Service was Restored: 10/17/2012 12:00:00 AM Summary: Windows Azure performed a planned change from using the Microsoft account service (formerly Windows Live ID) to the Azure Active Directory (AAD) as its primary authentication mechanism on August 24th.   This change was made to enable future innovation in the area of authentication – particularly for organizationally owned identities, identity federation, stronger authentication methods and compliance certification.   While this migration was largely transparent to Windows Azure users, a small number of users whose sign-in names were part of a Windows Live Custom Domain were unable to login.   This incompatibility was not discovered during the Quality Assurance testing phase prior to the migration. Customer Impact: Customers whose sign-in names were part of a Windows Live Custom Domain were unable to sign-in the Management Portal after ~4:00 p.m. PST on August 24th, 2012.   We determined that the issue did impact at least 127 users in 98 of these Windows Live Custom Domains and had a maximum potential impact of 1,110 users in total. Root Cause: The root cause of the issue was an incompatibility in the AAD authentication service to handle logins from Microsoft accounts whose sign-in names were part of a Windows Live Custom Domains.  This issue was not discovered during the Quality Assurance testing phase prior to the migration from Microsoft Account (MSA) to AAD. Mitigations: The issue was mitigated for the majority of affected users by 8:20 a.m. PST on August 25th, 2012 by running some internal scripts to correct many known Windows Live Custom Domains.   The remaining affected domains fell into two categories: Windows Live Custom Domains that were not corrected by 8/25/2012. An additional 48 Windows Live Custom Domains were fixed in the weeks following the incident within 2 business days after the AAD team received an escalation from product support regarding those accounts. Windows Live Custom domains that were also provisioned in Office365. Some of the affected Windows Live Custom Domains had already been provisioned in AAD because their owners signed up for Office365 which is a service that also uses AAD.   In these cases the Azure customers had to work around the issue by renaming their Microsoft Account or using a different Microsoft Account to administer their Azure subscription. Permanent Fix: The Azure Active Directory team permanently fixed the issue for all customers on 10/17/2012 in an upgraded release of the AAD service.

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• Fuji camera "mounts" but folder not in Dolphin After Kubuntu 13.10 upgrade

  - by user207207

  Fuji camera mount reported in attached devices but not visible in Dolphin After Kubuntu 13.10 upgrade Have reinstalled the driver, and a few other suggestions, for other cameras mounts failing on previous Ubuntu upgrades. I have already spent a couple of hours trying to get my photo's off the camera, very annoying. Worked perfectly in 11.04, 11.10, 12.04, 12.10 and 13.04. dmesg | tail; lsusb; lsb_release -a [ 6181.858786] CPUM: APIC 03 at 00000000fee00000 (mapped at ffffc90009400000) - ver 0x80050010, lint0=0x10700 lint1=0x10400 pc=0x00400 thmr=0x10000 [17261.396236] CPUM: APIC 00 at 00000000fee00000 (mapped at ffffc90000c6a000) - ver 0x80050010, lint0=0x10700 lint1=0x00400 pc=0x00400 thmr=0x10000 [17261.396239] CPUM: APIC 03 at 00000000fee00000 (mapped at ffffc90000c72000) - ver 0x80050010, lint0=0x10700 lint1=0x10400 pc=0x00400 thmr=0x10000 [17261.396241] CPUM: APIC 02 at 00000000fee00000 (mapped at ffffc90000c70000) - ver 0x80050010, lint0=0x10700 lint1=0x10400 pc=0x00400 thmr=0x10000 [17261.396255] CPUM: APIC 01 at 00000000fee00000 (mapped at ffffc90000c6e000) - ver 0x80050010, lint0=0x10700 lint1=0x10400 pc=0x00400 thmr=0x10000 [32456.884907] usb 2-5: new high-speed USB device number 2 using ehci-pci [32457.654046] usb 2-5: New USB device found, idVendor=04cb, idProduct=01e8 [32457.654050] usb 2-5: New USB device strings: Mfr=0, Product=2, SerialNumber=3 [32457.654052] usb 2-5: Product: Digital Camera [32457.654053] usb 2-5: SerialNumber: 4C3230302020091117CAA59WP18548 Bus 002 Device 002: ID 04cb:01e8 Fuji Photo Film Co., Ltd Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 001 Device 003: ID 2013:024f PCTV Systems nanoStick T2 290e Bus 001 Device 002: ID 046d:082d Logitech, Inc. HD Pro Webcam C920 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub No LSB modules are available. Distributor ID: Ubuntu vissibleDescription: Ubuntu 13.10 Release: 13.10 Codename: saucy sudo apt-get install gvfs-bin gvfs-mount gphoto2://[usb:002,002] Error mounting location: Error initializing camera: -108: No such file or directory ...... I have reported a bug in Dolphin, which has been transferred to Solid. Further information : I ran solid-hardware list details udi = '/org/kde/solid/udev/sys/devices/pci0000:00/0000:00:04.1/usb2/2-5' parent = '/org/kde/solid/udev' (string) vendor = '04cb' (string) product = 'Digital Camera' (string) description = 'Camera' (string) Block.major = 189 (0xbd) (int) Block.minor = 137 (0x89) (int) Block.device = '/dev/bus/usb/002/010' (string) Camera.supportedProtocols = {'ptp'} (string list) Camera.supportedDrivers = {'gphoto'} (string list) I still can't get my photo's off, I can see the folders using the Gimp menu. If anyone has got any ideas, I'm willing to try them.

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• Developing Schema Compare for Oracle (Part 6): 9i Query Performance

  - by Simon Cooper

  All throughout the EAP and beta versions of Schema Compare for Oracle, our main request was support for Oracle 9i. After releasing version 1.0 with support for 10g and 11g, our next step was then to get version 1.1 of SCfO out with support for 9i. However, there were some significant problems that we had to overcome first. This post will concentrate on query execution time. When we first tested SCfO on a 9i server, after accounting for various changes to the data dictionary, we found that database registration was taking a long time. And I mean a looooooong time. The same database that on 10g or 11g would take a couple of minutes to register would be taking upwards of 30 mins on 9i. Obviously, this is not ideal, so a poke around the query execution plans was required. As an example, let's take the table population query - the one that reads ALL_TABLES and joins it with a few other dictionary views to get us back our list of tables. On 10g, this query takes 5.6 seconds. On 9i, it takes 89.47 seconds. The difference in execution plan is even more dramatic - here's the (edited) execution plan on 10g: -------------------------------------------------------------------------------| Id | Operation | Name | Bytes | Cost |-------------------------------------------------------------------------------| 0 | SELECT STATEMENT | | 108K| 939 || 1 | SORT ORDER BY | | 108K| 939 || 2 | NESTED LOOPS OUTER | | 108K| 938 ||* 3 | HASH JOIN RIGHT OUTER | | 103K| 762 || 4 | VIEW | ALL_EXTERNAL_LOCATIONS | 2058 | 3 ||* 20 | HASH JOIN RIGHT OUTER | | 73472 | 759 || 21 | VIEW | ALL_EXTERNAL_TABLES | 2097 | 3 ||* 34 | HASH JOIN RIGHT OUTER | | 39920 | 755 || 35 | VIEW | ALL_MVIEWS | 51 | 7 || 58 | NESTED LOOPS OUTER | | 39104 | 748 || 59 | VIEW | ALL_TABLES | 6704 | 668 || 89 | VIEW PUSHED PREDICATE | ALL_TAB_COMMENTS | 2025 | 5 || 106 | VIEW | ALL_PART_TABLES | 277 | 11 |------------------------------------------------------------------------------- And the same query on 9i: -------------------------------------------------------------------------------| Id | Operation | Name | Bytes | Cost |-------------------------------------------------------------------------------| 0 | SELECT STATEMENT | | 16P| 55G|| 1 | SORT ORDER BY | | 16P| 55G|| 2 | NESTED LOOPS OUTER | | 16P| 862M|| 3 | NESTED LOOPS OUTER | | 5251G| 992K|| 4 | NESTED LOOPS OUTER | | 4243M| 2578 || 5 | NESTED LOOPS OUTER | | 2669K| 1440 ||* 6 | HASH JOIN OUTER | | 398K| 302 || 7 | VIEW | ALL_TABLES | 342K| 276 || 29 | VIEW | ALL_MVIEWS | 51 | 20 ||* 50 | VIEW PUSHED PREDICATE | ALL_TAB_COMMENTS | 2043 | ||* 66 | VIEW PUSHED PREDICATE | ALL_EXTERNAL_TABLES | 1777K| ||* 80 | VIEW PUSHED PREDICATE | ALL_EXTERNAL_LOCATIONS | 1744K| ||* 96 | VIEW | ALL_PART_TABLES | 852K| |------------------------------------------------------------------------------- Have a look at the cost column. 10g's overall query cost is 939, and 9i is 55,000,000,000 (or more precisely, 55,496,472,769). It's also having to process far more data. What on earth could be causing this huge difference in query cost? After trawling through the '10g New Features' documentation, we found item 1.9.2.21. Before 10g, Oracle advised that you do not collect statistics on data dictionary objects. From 10g, it advised that you do collect statistics on the data dictionary; for our queries, Oracle therefore knows what sort of data is in the dictionary tables, and so can generate an efficient execution plan. On 9i, no statistics are present on the system tables, so Oracle has to use the Rule Based Optimizer, which turns most LEFT JOINs into nested loops. If we force 9i to use hash joins, like 10g, we get a much better plan: -------------------------------------------------------------------------------| Id | Operation | Name | Bytes | Cost |-------------------------------------------------------------------------------| 0 | SELECT STATEMENT | | 7587K| 3704 || 1 | SORT ORDER BY | | 7587K| 3704 ||* 2 | HASH JOIN OUTER | | 7587K| 822 ||* 3 | HASH JOIN OUTER | | 5262K| 616 ||* 4 | HASH JOIN OUTER | | 2980K| 465 ||* 5 | HASH JOIN OUTER | | 710K| 432 ||* 6 | HASH JOIN OUTER | | 398K| 302 || 7 | VIEW | ALL_TABLES | 342K| 276 || 29 | VIEW | ALL_MVIEWS | 51 | 20 || 50 | VIEW | ALL_PART_TABLES | 852K| 104 || 78 | VIEW | ALL_TAB_COMMENTS | 2043 | 14 || 93 | VIEW | ALL_EXTERNAL_LOCATIONS | 1744K| 31 || 106 | VIEW | ALL_EXTERNAL_TABLES | 1777K| 28 |------------------------------------------------------------------------------- That's much more like it. This drops the execution time down to 24 seconds. Not as good as 10g, but still an improvement. There are still several problems with this, however. 10g introduced a new join method - a right outer hash join (used in the first execution plan). The 9i query optimizer doesn't have this option available, so forcing a hash join means it has to hash the ALL_TABLES table, and furthermore re-hash it for every hash join in the execution plan; this could be thousands and thousands of rows. And although forcing hash joins somewhat alleviates this problem on our test systems, there's no guarantee that this will improve the execution time on customers' systems; it may even increase the time it takes (say, if all their tables are partitioned, or they've got a lot of materialized views). Ideally, we would want a solution that provides a speedup whatever the input. To try and get some ideas, we asked some oracle performance specialists to see if they had any ideas or tips. Their recommendation was to add a hidden hook into the product that allowed users to specify their own query hints, or even rewrite the queries entirely. However, we would prefer not to take that approach; as well as a lot of new infrastructure & a rewrite of the population code, it would have meant that any users of 9i would have to spend some time optimizing it to get it working on their system before they could use the product. Another approach was needed. All our population queries have a very specific pattern - a base table provides most of the information we need (ALL_TABLES for tables, or ALL_TAB_COLS for columns) and we do a left join to extra subsidiary tables that fill in gaps (for instance, ALL_PART_TABLES for partition information). All the left joins use the same set of columns to join on (typically the object owner & name), so we could re-use the hash information for each join, rather than re-hashing the same columns for every join. To allow us to do this, along with various other performance improvements that could be done for the specific query pattern we were using, we read all the tables individually and do a hash join on the client. Fortunately, this 'pure' algorithmic problem is the kind that can be very well optimized for expected real-world situations; as well as storing row data we're not using in the hash key on disk, we use very specific memory-efficient data structures to store all the information we need. This allows us to achieve a database population time that is as fast as on 10g, and even (in some situations) slightly faster, and a memory overhead of roughly 150 bytes per row of data in the result set (for schemas with 10,000 tables in that means an extra 1.4MB memory being used during population). Next: fun with the 9i dictionary views.

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• Navigation in a #WP7 application with MVVM Light

  - by Laurent Bugnion

  In MVVM applications, it can be a bit of a challenge to send instructions to the view (for example a page) from a viewmodel. Thankfully, we have good tools at our disposal to help with that. In his excellent series “MVVM Light Toolkit soup to nuts”, Jesse Liberty proposes one approach using the MVVM Light messaging infrastructure. While this works fine, I would like to show here another approach using what I call a “view service”, i.e. an abstracted service that is invoked from the viewmodel, and implemented on the view. Multiple kinds of view services In fact, I use view services quite often, and even started standardizing them for the Windows Phone 7 applications I work on. If there is interest, I will be happy to show other such view services, for example Animation services, responsible to start/stop animations on the view. Dialog service, in charge of displaying messages to the user and gathering feedback. Navigation service, in charge of navigating to a given page directly from the viewmodel. In this article, I will concentrate on the navigation service. The INavigationService interface In most WP7 apps, the navigation service is used in quite a straightforward way. We want to: Navigate to a given URI. Go back. Be notified when a navigation is taking place, and be able to cancel. The INavigationService interface is quite simple indeed: public interface INavigationService { event NavigatingCancelEventHandler Navigating; void NavigateTo(Uri pageUri); void GoBack(); } Obviously, this interface can be extended if necessary, but in most of the apps I worked on, I found that this covers my needs. The NavigationService class It is possible to nicely pack the navigation service into its own class. To do this, we need to remember that all the PhoneApplicationPage instances use the same instance of the navigation service, exposed through their NavigationService property. In fact, in a WP7 application, it is the main frame (RootFrame, of type PhoneApplicationFrame) that is responsible for this task. So, our implementation of the NavigationService class can leverage this. First the class will grab the PhoneApplicationFrame and store a reference to it. Also, it registers a handler for the Navigating event, and forwards the event to the listening viewmodels (if any). Then, the NavigateTo and the GoBack methods are implemented. They are quite simple, because they are in fact just a gateway to the PhoneApplicationFrame. The whole class is as follows: public class NavigationService : INavigationService { private PhoneApplicationFrame _mainFrame; public event NavigatingCancelEventHandler Navigating; public void NavigateTo(Uri pageUri) { if (EnsureMainFrame()) { _mainFrame.Navigate(pageUri); } } public void GoBack() { if (EnsureMainFrame() && _mainFrame.CanGoBack) { _mainFrame.GoBack(); } } private bool EnsureMainFrame() { if (_mainFrame != null) { return true; } _mainFrame = Application.Current.RootVisual as PhoneApplicationFrame; if (_mainFrame != null) { // Could be null if the app runs inside a design tool _mainFrame.Navigating += (s, e) => { if (Navigating != null) { Navigating(s, e); } }; return true; } return false; } } Exposing URIs I find that it is a good practice to expose each page’s URI as a constant. In MVVM Light applications, a good place to do that is the ViewModelLocator, which already acts like a central point of setup for the views and their viewmodels. Note that in some cases, it is necessary to expose the URL as a string, for instance when a query string needs to be passed to the view. So for example we could have: public static readonly Uri MainPageUri = new Uri("/MainPage.xaml", UriKind.Relative); public const string AnotherPageUrl = "/AnotherPage.xaml?param1={0}&param2={1}"; Creating and using the NavigationService Normally, we only need one instance of the NavigationService class. In cases where you use an IOC container, it is easy to simply register a singleton instance. For example, I am using a modified version of a super simple IOC container, and so I can register the navigation service as follows: SimpleIoc.Register<INavigationService, NavigationService>(); Then, it can be resolved where needed with: SimpleIoc.Resolve<INavigationService>(); Or (more frequently), I simply declare a parameter on the viewmodel constructor of type INavigationService and let the IOC container do its magic and inject the instance of the NavigationService when the viewmodel is created. On supported platforms (for example Silverlight 4), it is also possible to use MEF. Or, of course, we can simply instantiate the NavigationService in the ViewModelLocator, and pass this instance as a parameter of the viewmodels’ constructor, injected as a property, etc… Once the instance has been passed to the viewmodel, it can be used, for example with: NavigationService.NavigateTo(ViewModelLocator.ComparisonPageUri); Testing Thanks to the INavigationService interface, navigation can be mocked and tested when the viewmodel is put under unit test. Simply implement and inject a mock class, and assert that the methods are called as they should by the viewmodel. Conclusion As usual, there are multiple ways to code a solution answering your needs. I find that view services are a really neat way to delegate view-specific responsibilities such as animation, dialogs and of course navigation to other classes through an abstracted interface. In some cases, such as the NavigationService class exposed here, it is even possible to standardize the implementation and pack it in a class library for reuse. I hope that this sample is useful! Happy coding. Laurent   Laurent Bugnion (GalaSoft) Subscribe | Twitter | Facebook | Flickr | LinkedIn

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• Oracle Linux Partner Pavilion Spotlight - Part II

  - by Ted Davis

  As we draw closer to the first day of Oracle OpenWorld, starting in less than a week, we continue to showcase some of our premier partners exhibiting in the Oracle Linux Partner Pavilion ( Booth #1033). We have Independent Hardware Vendors, Independent Software Vendors and Systems Integrators that show the breadth of support in the Oracle Linux and Oracle VM ecosystem. In today's post we highlight three additional Oracle Linux / Oracle VM Partners from the pavilion. Micro Focus delivers mainframe solutions software and software delivery tools with its Borland products. These tools are grouped under the following solutions: Analysis and testing tools for JDeveloper Micro Focus Enterprise Analyzer is key to the success of application overhaul and modernization strategies by ensuring that they are based on a solid knowledge foundation. It reveals the reality of enterprise application portfolios and the detailed constructs of business applications. COBOL for Oracle Database, Oracle Linux, and Tuxedo Micro Focus Visual COBOL delivers the next generation of COBOL development and deployment. Itbrings the productivity of the Eclipse IDE to COBOL, and provides the ability to deploy key business critical COBOL applications to Oracle Linux both natively and under a JVM. Migration and Modernization tooling for mainframes Enterprise application knowledge, development, test and workload re-hosting tools significantly improves the efficiency of business application delivery, enabling CIOs and IT leaders to modernize application portfolios and target platforms such as Oracle Linux. When it comes to Oracle Linux database environments, supporting high transaction rates with minimal response times is no longer just a goal. It’s a strategic imperative. The “data deluge” is impacting the ability of databases and other strategic applications to access data and provide real-time analytics and reporting. As such, customer demand for accelerated application performance is increasing. Visit LSI at the Oracle Linux Pavilion, #733, to find out how LSI Nytro Application Acceleration products are designed from the ground up for database acceleration. Our intelligent solid-state storage solutions help to eliminate I/O bottlenecks, increase throughput and enable Oracle customers achieve the highest levels of DB performance. Accelerate Your Exadata Success With Teleran. Teleran’s software solutions for Oracle Exadata and Oracle Database reduce the cost, time and effort of migrating and consolidating applications on Exadata. In addition Teleran delivers visibility and control solutions for BI/data warehouse performance and user management that ensure service levels and cost efficiency.Teleran will demonstrate these solutions at the Oracle Open World Linux Pavilion: Consolidation Accelerator - Reduces the cost, time and risk ofof migrating and consolidation applications on Exadata. Application Readiness – Identifies legacy application performance enhancements needed to take advantage of Exadata performance features Workload Accelerator – Identifies and clusters workloads for faster performance on Exadata Application Visibility and Control - Improves performance, user productivity, and alignment to business objectives while reducing support and resource costs. Thanks for reading today's Partner Spotlight. Three more partners will be highlighted tomorrow. If you missed our first Partner Spotlight check it out here.

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• Some Early Considerations

  - by Chris Massey

  Following on from my previous post, I want to say "thank you" to everyone who has got in touch and got involved – you are pioneers! An update on where we are right now: paper prototypes v1 To be more specific, we’ve picked two of the ideas that seem to have more pros than cons, turned them into Balsamiq mockups, and are getting them fleshed out with realistic content. We’ll initially make these available to the aforementioned pioneers (thank you again), roll in the feedback, and then open up to get more data on what works and what doesn’t. If you’ve got any questions about this (or what we’re working on right now), feel free to ask me in the comments below. I’ve had a few people express an interest in the process we’re going through, and I’m more than happy to share details more frequently as we go along – not least because you, dear reader, will help us stay on target and create something Good. To start with, here’s a quick flashback to bring you all up to speed. A Brief Retrospective As you may already know, we’re creating a new publishing asset specifically focused on providing great content for web developers. We don’t yet know exactly what this thing will look like, or exactly how it will work, but we know we want to create something that is useful different. For my part, I’m seriously excited at the prospect of building a genuinely digital publishing system (as opposed to what most publishing is these days, which is print-style publishing which just happens to be on the web). The main challenge at this point is working out our build-measure-assess loop to speed up our experimental turn-around, and that’ll get better as we run more trials. Of course, there are a few things we’ve been pondering at this early conceptual stage: Do we publishing about heterogeneous technology stacks from day 1, or do we start with ASP.NET (which we’re familiar with) & branch out later? There are challenges with either approach. What publishing "modes" are already being well-handled? For example, the likes of Pluralsight, TekPub, and Treehouse have pretty much nailed video training (debate about price, if you like), and unless we think we can do it faster / better / cheaper (unlikely, for the record), we should leave them to it. Where should we base whatever we create? Should we create a completely new asset under a new name, graft something onto Simple-Talk (like the labs), or just build something directly into Simple-Talk? It sounds trivial, but it does have at least some impact on infrastructure and what how we manage the different types of content we (will) have. Are there any obvious problems or niches that we think could address really well, or should we just throw ideas out and see what readers respond to? What kind of users do we want to provide for? This actually deserves a little bit of unpacking… Why are you here? We currently divide readers into (broadly) the categories: Category 1: I know nothing about X, and I’d like to learn about it. Category 2: I know something about X, but I’d like to learn how to do something specific with it. Category 3: Ah man, I have a problem with X, and I need to fix it now. Now that I think about it, I might also include a 4th class of reader: Category 4: I’m looking for something interesting to engage my brain. These are clearly task-based categorizations, and depending on which task you’re performing when you arrive here, you’re going to need different types of content, or will have specific discovery needs. One of the questions that’s at the back of my mind whenever I consider a new idea is “How many of the categories will this satisfy?” As an example, typical video training is very well suited to categories 1, 2, and 4. StackOverflow is very well suited to category 3, and serves as a sign-posting system to the rest. Clearly it’s not necessary to satisfy every category need to be useful and popular, but being aware of what behavior readers might be exhibiting when they arrive will help us tune our ideas appropriately. < / Flashback > We don’t have clean answers to most of these considerations – they’re things we’re aware of, and each idea we look at is going to be best suited to a different mix of the options I’ve described. Our first experimental loop will be coming full circle in the next few days, so we should start to see how the different possibilities vary between ideas. Free to chime in with questions and suggestions about anything I’ve just brain-dumped, or at any stage as we go along. If you see anything that intrigued or enrages you, or just have an idea you’d like to share, I’d love to hear from you.

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• Is there a factory pattern to prevent multiple instances for same object (instance that is Equal) good design?

  - by dsollen

  I have a number of objects storing state. There are essentially two types of fields. The ones that uniquely define what the object is (what node, what edge etc), and the others that store state describing how these things are connected (this node is connected to these edges, this edge is part of these paths) etc. My model is updating the state variables using package methods, so all these objects act as immutable to anyone not in Model scope. All Objects extend one base type. I've toyed with the idea of a Factory approach which accepts a Builder object and constructs the applicable object. However, if an instance of the object already exists (ie would return true if I created the object defined by the builder and passed it to the equal method for the existing instance) the factory returns the current object instead of creating a new instance. Because the Equal method would only compare what uniquely defines the type of object (this is node A to node B) but won't check the dynamic state stuff (node A is currently connected to nodes C and E) this would be a way of ensuring anyone that wants my Node A automatically knows its state connections. More importantly it would prevent aliasing nightmares of someone trying to pass an instance of node A with different state then the node A in my model has. I've never heard of this pattern before, and it's a bit odd. I would have to do some overriding of serialization methods to make it work (ensure that when I read in a serilized object I add it to my facotry list of known instances, and/or return an existing factory in its place), as well as using a weakHashMap as if it was a weakHashSet to know whether an instance exists without worrying about a quasi-memory leak occuring. I don't know if this is too confusing or prone to its own obscure bugs. One thing I know is that plugins interface with lowest level hardware. The plugins have to be able to return state that is different than my memory; to tell my memory when its own state is inconsistent. I believe this is possible despite their fetching objects that exist in my memory; we allow building of objects without checking their consistency with the model until the addToModel is called anyways; and the existing plugins design was written before all this extra state existed and worked fine without ever being aware of it. Should I just be using some other design to avoid this crazyness? (I have another question to that affect that I'm posting).

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• Tech Talk: Managing Cloud Integration

  - by Tanu Sood

  Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Cloud computing solutions are widely hailed as a way to reduce capital expenditures yet organizations are realizing they need to also consider all of the nuances of integrating cloud applications with existing information systems.Cloud integration, after all, has a direct impact on your costs, maintenance and upgrade efforts. Catch this conversation on Tech Talk with Oracle Vice President, Amit Zavery, to understand how Oracle Fusion Middleware provides a simple and consistent method to maintaining integration interfaces across disparate systems across cloud and on-premise applications. Simplify your IT infrastructure and seamlessly manage data and application integration across your applications with Oracle solutions. Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} For other Fusion Middleware talks, subscribe to Fusion Middleware Radio today and visit us on oracle.com Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Photo courtesy: www.cloudtweaks.com

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• Developing Schema Compare for Oracle (Part 4): Script Configuration

  - by Simon Cooper

  If you've had a chance to play around with the Schema Compare for Oracle beta, you may have come across this screen in the synchronization wizard: This screen is one of the few screens that, along with the project configuration form, doesn't come from SQL Compare. This screen was designed to solve a couple of issues that, although aren't specific to Oracle, are much more of a problem than on SQL Server: Datatype conversions and NOT NULL columns. 1. Datatype conversions SQL Server is generally quite forgiving when it comes to datatype conversions using ALTER TABLE. For example, you can convert from a VARCHAR to INT using ALTER TABLE as long as all the character values are parsable as integers. Oracle, on the other hand, only allows ALTER TABLE conversions that don't change the internal data format. Essentially, every change that requires an actual datatype conversion has to be done using a rebuild with a conversion function. That's OK, as we can simply hard-code the various conversion functions for the valid datatype conversions and insert those into the rebuild SELECT list. However, as there always is with Oracle, there's a catch. Have a look at the NUMTODSINTERVAL function. As well as specifying the value (or column) to convert, you have to specify an interval_unit, which tells oracle how to interpret the input number. We can't hardcode a default for this parameter, as it is entirely dependent on the user's data context! So, in order to convert NUMBER to INTERVAL DAY TO SECOND/INTERVAL YEAR TO MONTH, we need to have feedback from the user as to what to put in this parameter while we're generating the sync script - this requires a new step in the engine action/script generation to insert these values into the script, as well as new UI to allow the user to specify these values in a sensible fashion. In implementing the engine and UI infrastructure to allow this it made much more sense to implement it for any rebuild datatype conversion, not just NUMBER to INTERVALs. For conversions which we can do, we pre-fill the 'value' box with the appropriate function from the documentation. The user can also type in arbitary SQL expressions, which allows the user to specify optional format parameters for the relevant conversion functions, or indeed call their own functions to convert between values that don't have a built-in conversion defined. As the value gets inserted as-is into the rebuild SELECT list, any expression that is valid in that context can be specified as the conversion value. 2. NOT NULL columns Another problem that is solved by the new step in the sync wizard is adding a NOT NULL column to a table. If the table contains data (as most database tables do), you can't just add a NOT NULL column, as Oracle doesn't know what value to put in the new column for existing rows - the DDL statement will fail. There are actually 3 separate scenarios for this problem that have separate solutions within the engine: Adding a NOT NULL column to a table without a rebuild Here, the workaround is to add a column default with an appropriate value to the column you're adding: ALTER TABLE tbl1 ADD newcol NUMBER DEFAULT <value> NOT NULL; Note, however, there is something to bear in mind about this solution; once specified on a column, a default cannot be removed. To 'remove' a default from a column you change it to have a default of NULL, hence there's code in the engine to treat a NULL default the same as no default at all. Adding a NOT NULL column to a table, where a separate change forced a table rebuild Fortunately, in this case, a column default is not required - we can simply insert the default value into the rebuild SELECT clause. Changing an existing NULL to a NOT NULL column To implement this, we run an UPDATE command before the ALTER TABLE to change all the NULLs in the column to the required default value. For all three, we need some way of allowing the user to specify a default value to use instead of NULL; as this is essentially the same problem as datatype conversion (inserting values into the sync script), we can re-use the UI and engine implementation of datatype conversion values. We also provide the option to alter the new column to allow NULLs, or to ignore the problem completely. Note that there is the same (long-running) problem in SQL Compare, but it is much more of an issue in Oracle as you cannot easily roll back executed DDL statements if the script fails at some point during execution. Furthermore, the engine of SQL Compare is far less conducive to inserting user-supplied values into the generated script. As we're writing the Schema Compare engine from scratch, we used what we learnt from the SQL Compare engine and designed it to be far more modular, which makes inserting procedures like this much easier.

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• Java @Contented annotation to help reduce false sharing

  - by Dave

  See this posting by Aleksey Shipilev for details -- @Contended is something we've wanted for a long time. The JVM provides automatic layout and placement of fields. Usually it'll (a) sort fields by descending size to improve footprint, and (b) pack reference fields so the garbage collector can process a contiguous run of reference fields when tracing. @Contended gives the program a way to provide more explicit guidance with respect to concurrency and false sharing. Using this facility we can sequester hot frequently written shared fields away from other mostly read-only or cold fields. The simple rule is that read-sharing is cheap, and write-sharing is very expensive. We can also pack fields together that tend to be written together by the same thread at about the same time. More generally, we're trying to influence relative field placement to minimize coherency misses. Fields that are accessed closely together in time should be placed proximally in space to promote cache locality. That is, temporal locality should condition spatial locality. Fields accessed together in time should be nearby in space. That having been said, we have to be careful to avoid false sharing and excessive invalidation from coherence traffic. As such, we try to cluster or otherwise sequester fields that tend to written at approximately the same time by the same thread onto the same cache line. Note that there's a tension at play: if we try too hard to minimize single-threaded capacity misses then we can end up with excessive coherency misses running in a parallel environment. Theres no single optimal layout for both single-thread and multithreaded environments. And the ideal layout problem itself is NP-hard. Ideally, a JVM would employ hardware monitoring facilities to detect sharing behavior and change the layout on the fly. That's a bit difficult as we don't yet have the right plumbing to provide efficient and expedient information to the JVM. Hint: we need to disintermediate the OS and hypervisor. Another challenge is that raw field offsets are used in the unsafe facility, so we'd need to address that issue, possibly with an extra level of indirection. Finally, I'd like to be able to pack final fields together as well, as those are known to be read-only.

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• Ubuntu 12.4.1 failing in vm both Vbox and Vmware on new HP Envy 4t-1000

  - by Chas

  Brand new to Linux, getting frustrated trying to get an environment up with Ubuntu. My primary goal is to learn Linux and Apache/PHP development. I need to keep my Windows OS as main on my machine for work, so i'm trying to virtualize Ubuntu 12.4.1 without luck (many attempts). I have a new HP Envy 4t-1000 with 16gb ram, and 32 gb ssd caching with 500gb spindle hard drive. Graphics card is an Intel HD 3000 with AMD Radeon 7670M. With installing Ubuntu desktop in VBox, I'm getting this result: https://forums.virtualbox.org/viewtopic.php?f=6&t=51939 With VMware workstation 7 (patched), I complete the install of Ubuntu, it reboots, purple desktop briefly flashes then it drops to command line. I bought a beginning Ubuntu book, and it recommends trying to manually configure graphics if this happens. So I tried doing a safe boot holding shift - I get to the first screen (GRUB) loads fine, and I choose recovery mode. After choosing the recovery mode, I get the recovery mode options, and can arrow down to what the book suggests 'Run in fail safe graphic mode.' Once I select this option, I get a black screen with a large white dialogue box, at the top it says "The system is running in low-graphics mode. Your screen, graphics card, and input device settings could not be detected correctly. You will need to configure these yourself." Then there is an ok button way down at the bottom. When I select 'ok' I get a menu for a few options, book recommended 'reconfigure graphics.' When I try this, I get a menu of two options: 1) "Use generic (default) configuration or 2) use backup. I've tried both options several times, hitting ok just refreshes screen and nothing more. Rebooting at this point just goes back to command line as before. I don't know what to do at this point, I've spent too many hours this weekend trying in both VBox and VMware to get Ubuntu going. Isn't there like a very basic graphic display or something I can use to at least get into the desktop? I explored the GRUB some more, and tried to look at the startup and xserver logs - both are blank. No help there I guess? When I try to choose 'Edit the configuration file, then 'ok' screen just refreshes on same menu options, nothing happens. thx for any advice. I really need to focus on learning Linux, Apache and PHP, so perhaps Ubuntu just won't work on my hardware? Any other suggestions? I will need to virtualize - THANKS for any help/advice.

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• Software Architecture Analysis Method (SAAM)

  Software Architecture Analysis Method (SAAM) is a methodology used to determine how specific application quality attributes were achieved and how possible changes in the future will affect quality attributes based on hypothetical cases studies. Common quality attributes that can be utilized by this methodology include modifiability, robustness, portability, and extensibility. Quality Attribute: Application Modifiability The Modifiability quality attribute refers to how easy it changing the system in the future will be. This to me is a very open-ended attribute because a business could decide to transform a Point of Sale (POS) system in to a Lead Tracking system overnight. (Yes, this did actually happen to me) In order for SAAM to be properly applied for checking this attribute specific hypothetical case studies need to be created and review for the modifiability attribute due to the fact that various scenarios would return various results based on the amount of changes. In the case of the POS change out a payment gateway or adding an additional payment would have scored very high in comparison to changing the system over to a lead management system. I personally would evaluate this quality attribute based on the S.O.I.L.D Principles of software design. I have found from my experience the use of S.O.I.L.D in software design allows for the adoption of changes within a system. Quality Attribute: Application Robustness The Robustness quality attribute refers to how an application handles the unexpected. The unexpected can be defined but is not limited to anything not anticipated in the originating design of the system. For example: Bad Data, Limited to no network connectivity, invalid permissions, or any unexpected application exceptions. I would personally evaluate this quality attribute based on how the system handled the exceptions. Robustness Considerations Did the system stop or did it handle the unexpected error? Did the system log the unexpected error for future debugging? What message did the user receive about the error? Quality Attribute: Application Portability The Portability quality attribute refers to the ease of porting an application to run in a new operating system or device. For example, It is much easier to alter an ASP.net website to be accessible by a PC, Mac, IPhone, Android Phone, Mini PC, or Table in comparison to desktop application written in VB.net because a lot more work would be involved to get the desktop app to the point where it would be viable to port the application over to the various environments and devices. I would personally evaluate this quality attribute based on each new environment for which the hypothetical case study identifies. I would pay particular attention to the following items. Portability Considerations Hardware Dependencies Operating System Dependencies Data Source Dependencies Network Dependencies and Availabilities  Quality Attribute: Application Extensibility The Extensibility quality attribute refers to the ease of adding new features to an existing application without impacting existing functionality. I would personally evaluate this quality attribute based on each new environment for the following Extensibility  Considerations Hard coded Variables versus Configurable variables Application Documentation (External Documents and Codebase Documentation.) The use of Solid Design Principles

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• WHERE x = @x OR @x IS NULL

  - by steveh99999

  Every SQL DBA and developer should read the blog of MVP Erland Sommarskog – but particularly  his article on dynamic search conditions in T-SQL. I’ve linked above to his SQL 2005 article but his 2008 version is also a must-read. I seem to regularly come across uses of the SQL in the title above… Erland’s article explains in detail why this is inefficient, but I came across a nice example recently… A stored procedure contained the following code :- WHERE @Name is null or [Name] like @Name as a nonclustered index exists on the Name column, you might assume this would be handled efficiently by SQL Server. However, I got the following output from SET STATISTICS IO Table 'xxxxx'. Scan count 15, logical reads 47760, physical reads 9, read-ahead reads 13872, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0. Note the high number of logical reads… After a bit of investigation, we found that @Name could never actually be set to NULL in this particular example. ie the @x IS NULL was spurious… So, we changed the call to WHERE  [Name] like @Name Now, how much more efficient is this code ? Table 'xxxxx'. Scan count 3, logical reads 24, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0 A nice easy win in this case…… a full index scan has been replaced by a significantly more efficient index seek. I managed to recreate the same behaviour on Adventureworks – here’s a quick query to demonstrate :- USE adventureworks SET STATISTICS IO ON DECLARE @id INT = 51721 SELECT * FROM Sales.SalesOrderDetail WHERE @id IS NULL OR salesorderid = @id SELECT * FROM Sales.SalesOrderDetail WHERE salesorderid = @id Take a look at the STATISTICS IO output and compare the actual query plans used to prove the impact of  WHERE @id IS NULL. And just to follow some of Erland’s advice – here’s how you could get similar performance if it was possible that @id could actually sometimes contain NULL. DECLARE @sql NVARCHAR(4000), @parameterlist NVARCHAR(4000) DECLARE @id INT = 51721 – or change to NULL to prove query is functionally correct SET @sql = 'SELECT * FROM Sales.SalesOrderDetail WHERE 1 = 1' IF @id IS NOT NULL SET @sql = @sql + ' AND salesorderid = @id' IF @id IS NULL SET @sql = @sql + ' AND salesorderid IS NULL' SET @parameterlist = '@id INT' EXEC sp_executesql @sql, @parameterlist,@id Sometimes I think we focus too much on hardware and SQL Server configuration – when really the answer is focus on writing efficient SQL.

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