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• Head in the Clouds

  - by Tony Davis

  We're just past the second anniversary of the launch of Windows Azure. A couple of years' experience with Azure in the industry has provided some obvious success stories, but has deflated some of the initial marketing hyperbole. As a general principle, Azure seems to work well in providing a Service-Oriented Architecture for services in enterprises that suffer wide fluctuations in demand. Instead of being obliged to provide hardware sufficient for the occasional peaks in demand, one can hire capacity only when it is needed, and the cost of hosting an application is no longer a capital cost. It enables companies to avoid having to scale out hardware for peak periods only to see it underused for the rest of the time. A customer-facing application such as a concert ticketing system, which suffers high demand in short, predictable bursts of activity, is a great example of an application that would work well in Azure. However, moving existing applications to Azure isn't something to be done on impulse. Unless your application is .NET-based, and consists of 'stateless' components that communicate via queues, you are probably in for a lot of redevelopment work. It makes most sense for IT departments who are already deep in this .NET mindset, and who also want 'grown-up' methods of staging, testing, and deployment. Azure fits well with this culture and offers, as a bonus, good Visual Studio integration. The most-commonly stated barrier to porting these applications to Azure is the problem of reconciling the use of the cloud with legislation for data privacy and security. Putting databases in the cloud is a sticky issue for many and impossible for some due to compliance and security issues, the need for direct control over data, and so on. In the face of feedback from the early adopters of Azure, Microsoft has broadened the architectural choices to cater for a wide range of requirements. As well as SQL Azure Database (SAD) and Azure storage, the unstructured 'BLOB and Entity-Attribute-Value' NoSQL storage alternative (which equates more closely with folders and files than a database), Windows Azure offers a wide range of storage options including use of services such as oData: developers who are programming for Windows Azure can simply choose the one most appropriate for their needs. Secondly, and crucially, the Windows Azure architecture allows you the freedom to produce hybrid applications, where only those parts that need cloud-based hosting are deployed to Azure, whereas those parts that must unavoidably be hosted in a corporate datacenter can stay there. By using a hybrid architecture, it will seldom, if ever, be necessary to move an entire application to the cloud, along with personal and financial data. For example that we could port to Azure only put those parts of our ticketing application that capture and process tickets orders. Once an order is captured, the financial side can be processed in our own data center. In short, Windows Azure seems to be a very effective way of providing services that are subject to wide but predictable fluctuations in demand. Have you come to the same conclusions, or do you think I've got it wrong? If you've had experience with Azure, would you recommend it? It would be great to hear from you. Cheers, Tony.

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• Comparing Apples and Pairs

  - by Tony Davis

  A recent study, High Costs and Negative Value of Pair Programming, by Capers Jones, pulls no punches in its assessment of the costs-to- benefits ratio of pair programming, two programmers working together, at a single computer, rather than separately. He implies that pair programming is a method rushed into production on a wave of enthusiasm for Agile or Extreme Programming, without any real regard for its effectiveness. Despite admitting that his data represented a far from complete study of the economics of pair programming, his conclusions were stark: it was 2.5 times more expensive, resulted in a 15% drop in productivity, and offered no significant quality benefits. The author provides a more scientific analysis than Jon Evans’ Pair Programming Considered Harmful, but the theme is the same. In terms of upfront-coding costs, pair programming is surely more expensive. The claim of productivity loss is dubious and contested by other studies. The third claim, though, did surprise me. The author’s data suggests that if both the pair and the individual programmers employ static code analysis and testing, then there is no measurable difference in the resulting code quality, in terms of defects per function point. In other words, pair programming incurs a massive extra cost for no tangible return in investment. There were, inevitably, many criticisms of his data and his conclusions, a few of which are persuasive. Firstly, that the driver/observer model of pair programming, on which the study bases its findings, is far from the most effective. For example, many find Ping-Pong pairing, based on use of test-driven development, far more productive. Secondly, that it doesn’t distinguish between “expert” and “novice” pair programmers– that is, independently of other programming skills, how skilled was an individual at pair programming. Thirdly, that his measure of quality is too narrow. This point rings true, certainly at Red Gate, where developers don’t pair program all the time, but use the method in short bursts, while tackling a tricky problem and needing a fresh perspective on the best approach, or more in-depth knowledge in a particular domain. All of them argue that pair programming, and collective code ownership, offers significant rewards, if not in terms of immediate “bug reduction”, then in removing the likelihood of single points of failure, and improving the overall quality and longer-term adaptability/maintainability of the design. There is also a massive learning benefit for both participants. One developer told me how he once worked in the same team over consecutive summers, the first time with no pair programming and the second time pair-programming two-thirds of the time, and described the increased rate of learning the second time as “phenomenal”. There are a great many theories on how we should develop software (Scrum, XP, Lean, etc.), but woefully little scientific research in their effectiveness. For a group that spends so much time crunching other people’s data, I wonder if developers spend enough time crunching data about themselves. Capers Jones’ data may be incomplete, but should cause a pause for thought, especially for any large IT departments, supporting commerce and industry, who are considering pair programming. It certainly shouldn’t discourage teams from exploring new ways of developing software, as long as they also think about how to gather hard data to gauge their effectiveness.

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• We have our standards, and we need them

  - by Tony Davis

  The presenter suddenly broke off. He was midway through his section on how to apply to the relational database the Continuous Delivery techniques that allowed for rapid-fire rounds of development and refactoring, while always retaining a “production-ready” state. He sighed deeply and then launched into an astonishing diatribe against Database Administrators, much of his frustration directed toward Oracle DBAs, in particular. In broad strokes, he painted the picture of a brave new deployment philosophy being frustratingly shackled by the relational database, and by especially by the attitudes of the guardians of these databases. DBAs, he said, shunned change and “still favored tools I’d have been embarrassed to use in the ’80′s“. DBAs, Oracle DBAs especially, were more attached to their vendor than to their employer, since the former was the primary source of their career longevity and spectacular remuneration. He contended that someone could produce the best IDE or tool in the world for Oracle DBAs and yet none of them would give a stuff, unless it happened to come from the “mother ship”. I sat blinking in astonishment at the speaker’s vehemence, and glanced around nervously. Nobody in the audience disagreed, and a few nodded in assent. Although the primary target of the outburst was the Oracle DBA, it made me wonder. Are we who work with SQL Server, database professionals or merely SQL Server fanbois? Do DBAs, in general, have an image problem? Is it a good career-move to be seen to be holding onto a particular product by the whites of our knuckles, to the exclusion of all else? If we seek a broad, open-minded, knowledge of our chosen technology, the database, and are blessed with merely mortal powers of learning, then we like standards. Vendors of RDBMSs generally don’t conform to standards by instinct, but by customer demand. Microsoft has made great strides to adopt the international SQL Standards, where possible, thanks to considerable lobbying by the community. The implementation of Window functions is a great example. There is still work to do, though. SQL Server, for example, has an unusable version of the Information Schema. One cast-iron rule of any RDBMS is that we must be able to query the metadata using the same language that we use to query the data, i.e. SQL, and we do this by running queries against the INFORMATION_SCHEMA views. Developers who’ve attempted to apply a standard query that works on MySQL, or some other database, but doesn’t produce the expected results on SQL Server are advised to shun the Standards-based approach in favor of the vendor-specific one, using the catalog views. The argument behind this is sound and well-documented, and of course we all use those catalog views, out of necessity. And yet, as database professionals, committed to supporting the best databases for the business, whatever they are now and in the future, surely our heart should sink somewhat when we advocate a vendor specific approach, to a developer struggling with something as simple as writing a guard clause. And when we read messages on the Microsoft documentation informing us that we shouldn’t rely on INFORMATION_SCHEMA to identify reliably the schema of an object, in SQL Server!

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• You are or will be a laid off programmer - what do you do a year ago, right now, tomorrow, and next week?

  - by Adam Davis

  Many programmers, software engineers, and other technology professionals are out of work, facing layoffs, or are unprepared for layoffs though they feel secure right now. What should every programmer do right now (even if secure in their current job) to prepare them for layoffs down the road? If your boss came to your cubicle while you read this and laid you off: What would you do immediately after? What would you do tomorrow? What would you do next week? It obvious that one should always have an up to date resume, always get recommendations from people when they see you at your best (not when you're looking for a new job), etc. What are the things, step by step, that every programmer should do (or should consider doing) long before they are laid off, when they're laid off, and shortly after being laid off? This is a question with many possible facets. While I want to encourage discussion to center around programming career based answers, please reconsider before downvoting someone because they're thinking in terms of how they're going to prevent going into debt. Bonus catch-22 type question: You can study a new language or technology while out of work, but most places want you to have more than 1-2 months experience in a working environment, not just from a learning exercise. Is it worthwhile to place a priority on new (ideally in demand) skills, or should you instead hone existing skills?

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• Oracle Linux Partner Pavilion Spotlight - Part IV

  - by Ted Davis

  Welcome to the final Oracle Linux Partner Pavilion Spotlight Part IV.  Two days left till the Big Show. You are gearing up. We are gearing up. You can feel the excitement.  We can feel the excitement. This. Will. Be. The. Best. Show. EVER. See you at the Partner Pavilion (Moscone south # 1033) at Oracle OpenWorld. - Oracle Linux / Oracle VM Team HP and Oracle are pleased to announce another Oracle Validated Configuration based on the ProLiant DL980 server. Many choose to deploy Oracle workloads on the ProLiant DL980 based on the cost/performance ratio they achieve running Oracle Linux Unbreakable Enterprise Kernel. You can be confident that Oracle Validated Configurations based on ProLiant servers will help you achieve your most demanding performance goals. QLogic The QLogic-Oracle partnership spans over 20 years resulting in the most comprehensive line of Oracle Linux I/O adapter technology. Interface options include Ethernet, Fibre-Channel, and FCoE. Host side connectivity is offered in both low profile PCIe and Express Module PCIe form factors. QLogic software drives are jointly qualified and “in-box” with Oracle Linux 5.x, 6,x and Oracle VM enabling simplified installation and management while simultaneously taking risk out of the solution. Bringing innovations such as NPIV, T10-PI, and intelligent caching adapter technology to the Oracle Linux environment further strengthens the QLogic advantage. A big thank you to all of our Oracle Linux Partner Pavilion participants. We - they- look forward to meeting you next week at Oracle OpenWorld. If you've missed our three previous Partner Spotlight's - here are the links: Part I, Part II, Part III. 

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• On the art of self-promotion

  - by Tony Davis

  I attended Brent Ozar's Building the Fastest SQL Servers session at Tech Ed last week, and found myself engulfed in a 'perfect storm' of excellent technical and presentational skills coupled with an astute awareness of the value of promoting one's work. I spend a lot of time at such events talking to developers and DBAs about the value of blogging and writing articles, and my impression is that some could benefit from a touch less modesty and a little more self-promotion. I sense a reticence in many would-be writers. Is what I have to say important enough? Haven't far more qualified and established commentators, MVPs and so on, already said it? While it's a good idea to pick reasonably fresh and interesting topics, it's more important not to let such fears lead to writer's block. In the eyes of any future employer, your published writing is an extension of your resume. They will not care that a certain MVP knows how to solve problem x, but they will be very interested to see that you have tackled that same problem, and solved it in your own way, and described the process in your own voice. In your current job, your writing is one of the ways you can express to your peers, and to the organization as a whole, the value of what you contribute. Many Developers and DBAs seem to rely on the idea that their work will speak for itself, and that their skill shines out from it. Unfortunately, this isn't always true. Many Development DBAs, for example, will be painfully aware of the massive effort involved in tuning and adding resilience to rapidly developed applications. However, others in the organization who are unaware of what's involved in getting an application that is 'done' ready for production may dismiss such efforts as fussiness or conservatism. At the dark end of the development cycle, chickens come home to roost, but their droppings tend to land on those trying to clear up the mess. My advice is this: next time you fix a bug or improve the resilience or performance of a database or application, make sure that you use team meetings, informal discussions and so on to ensure that people understand what the problem was and what you had to do to fix it. Use your blog to describe, generally, the process you adopted, the resources you used and the insights that came from your work. Encourage your colleagues to do the same. By spreading the art of self-promotion to everyone involved in an IT project, we get a better idea of the extent of the work and the value of the contribution of all the team members. As always, we'd love to hear what you think. This very week, Simple-talk launches its new blogging platform. If any of this has moved you to 'throw your hat into the ring', drop us a mail at [email protected]. Cheers, Tony.

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• Data Model Dissonance

  - by Tony Davis

  So often at the start of the development of database applications, there is a premature rush to the keyboard. Unless, before we get there, we’ve mapped out and agreed the three data models, the Conceptual, the Logical and the Physical, then the inevitable refactoring will dog development work. It pays to get the data models sorted out up-front, however ‘agile’ you profess to be. The hardest model to get right, the most misunderstood, and the one most neglected by the various modeling tools, is the conceptual data model, and yet it is critical to all that follows. The conceptual model distils what the business understands about itself, and the way it operates. It represents the business rules that govern the required data, its constraints and its properties. The conceptual model uses the terminology of the business and defines the most important entities and their inter-relationships. Don’t assume that the organization’s understanding of these business rules is consistent or accurate. Too often, one department has a subtly different understanding of what an entity means and what it stores, from another. If our conceptual data model fails to resolve such inconsistencies, it will reduce data quality. If we don’t collect and measure the raw data in a consistent way across the whole business, how can we hope to perform meaningful aggregation? The conceptual data model has more to do with business than technology, and as such, developers often regard it as a worthy but rather arcane ceremony like saluting the flag or only eating fish on Friday. However, the consequences of getting it wrong have a direct and painful impact on many aspects of the project. If you adopt a silo-based (a.k.a. Domain driven) approach to development), you are still likely to suffer by starting with an incomplete knowledge of the domain. Even when you have surmounted these problems so that the data entities accurately reflect the business domain that the application represents, there are likely to be dire consequences from abandoning the goal of a shared, enterprise-wide understanding of the business. In reading this, you may recall experiences of the consequence of getting the conceptual data model wrong. I believe that Phil Factor, for example, witnessed the abandonment of a multi-million dollar banking project due to an inadequate conceptual analysis of how the bank defined a ‘customer’. We’d love to hear of any examples you know of development projects poleaxed by errors in the conceptual data model. Cheers, Tony

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• Why does 12.04 try but fail to hibernate, even after I enabled hibernation?

  - by Roger Davis

  Regarding the below (-----) info from another post, my system will try (as is said below) to hibernate, but it won't get all the way there. Hard drive activity stops, but it does not shut down. If I turn the power off, then back on, it will start, but I have to "restore previous session" in the browser and other open apps don't restart, with the accompanying hassle. So because it tries, will the suggested fix then cause it to work correctly, or is the literal "try" not really what he means?!? PLEASE NOTE - this is a desktop system, not a laptop. Before enabling hibernation, please try to test whether it works correctly by running pm-hibernate in a terminal. The system will try to hibernate. If you are able to start the system again then you are more or less safe to add an override. To do so, start editing sudo nano /etc/polkit-1/localauthority/50-local.d/com.ubuntu.enable-hibernate.pkla Fill it with this [Re-enable hibernate by default] Identity=unix-user:* Action=org.freedesktop.upower.hibernate ResultActive=yes Save by pressing Ctrl-O and exit nano by pressing Ctrl-X Restart and hibernation is back!

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• The long road to bug-free software

  - by Tony Davis

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

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• 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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• Consuming too much power on a Dell 15R

  - by Daniel Davis

  I'm new to Ubuntu, and I've just installed Ubuntu 11.10, and I must say I really like it a lot. I'm getting used to Ubuntu faster than I thought but the only issue I'm having is the power consumption. I have a " dell 15R with BIOS a07" and I uninstalled Ubuntu 11.04 because of some glitches I hated. None of those appear on this Ubuntu but now my computer discharges way too quick. when I check the power icon, it states that I have like 3:45 min remaining, which is fairly the same as what win7 and Ubuntu 11.04 used to tell me but 15 min later I check again and it gives me only 1:15 min remaining. Also, my computer seems to get a lot hotter than it used to. Is there more options to control the power usage on my laptop?

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• Instantiating objects in Java

  - by Davis Naglis

  I'm learning now Java from scratch and when I started to learn about instantiating objects, I don't understand - in which cases do I need to instantiate objects? For example I'm studying from TutsPlus course about it and there is example about "Rectangle" class. Instructor says that it needs to be instantiated. So I started to doubt about - when do I need to instantiate those objects when writing Java code?

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• Concurrent Affairs

  - by Tony Davis

  I once wrote an editorial, multi-core mania, on the conundrum of ever-increasing numbers of processor cores, but without the concurrent programming techniques to get anywhere near exploiting their performance potential. I came to the.controversial.conclusion that, while the problem loomed for all procedural languages, it was not a big issue for the vast majority of programmers. Two years later, I still think most programmers don't concern themselves overly with this issue, but I do think that's a bigger problem than I originally implied. Firstly, is the performance boost from writing code that can fully exploit all available cores worth the cost of the additional programming complexity? Right now, with quad-core processors that, at best, can make our programs four times faster, the answer is still no for many applications. But what happens in a few years, as the number of cores grows to 100 or even 1000? At this point, it becomes very hard to ignore the potential gains from exploiting concurrency. Possibly, I was optimistic to assume that, by the time we have 100-core processors, and most applications really needed to exploit them, some technology would be around to allow us to do so with relative ease. The ideal solution would be one that allows programmers to forget about the problem, in much the same way that garbage collection removed the need to worry too much about memory allocation. From all I can find on the topic, though, there is only a remote likelihood that we'll ever have a compiler that takes a program written in a single-threaded style and "auto-magically" converts it into an efficient, correct, multi-threaded program. At the same time, it seems clear that what is currently the most common solution, multi-threaded programming with shared memory, is unsustainable. As soon as a piece of state can be changed by a different thread of execution, the potential number of execution paths through your program grows exponentially with the number of threads. If you have two threads, each executing n instructions, then there are 2^n possible "interleavings" of those instructions. Of course, many of those interleavings will have identical behavior, but several won't. Not only does this make understanding how a program works an order of magnitude harder, but it will also result in irreproducible, non-deterministic, bugs. And of course, the problem will be many times worse when you have a hundred or a thousand threads. So what is the answer? All of the possible alternatives require a change in the way we write programs and, currently, seem to be plagued by performance issues. Software transactional memory (STM) applies the ideas of database transactions, and optimistic concurrency control, to memory. However, working out how to break down your program into sufficiently small transactions, so as to avoid contention issues, isn't easy. Another approach is concurrency with actors, where instead of having threads share memory, each thread runs in complete isolation, and communicates with others by passing messages. It simplifies concurrent programs but still has performance issues, if the threads need to operate on the same large piece of data. There are doubtless other possible solutions that I haven't mentioned, and I would love to know to what extent you, as a developer, are considering the problem of multi-core concurrency, what solution you currently favor, and why. Cheers, Tony.

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• The long road to bug-free software

  - by Tony Davis

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

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• Oracle Linux Partner Pavilion Spotlight III

  - by Ted Davis

  Three days until Oracle OpenWorld 2012 begins. The anticipation and excitement are building. In today's spotlight we are presenting an additional three partners exhibiting in the Oracle Linux Partner Pavilion at Oracle OpenWorld ( Booth #1033). Fujitsu will showcase a Gold tower system representing the one-millionth PRIMERGY server shipped, highlighting Fujitsu’s position as the #4 server vendor worldwide. Fujitsu’s broad range of server platforms is reshaping the data center with virtualization and cloud services, including those based on Oracle Linux and Oracle VM. BeyondTrust, the leader in providing context aware security intelligence, will be showcasing its threat management and policy enablement solutions for addressing IT security risks and simplifying compliance. BeyondTrust will discuss how to reduce security risks, close security gaps and improve visibility across your server and database infrastructure. Please stop by to see live demonstrations of BeyondTrust’s award winning vulnerability management and privilege identity management solutions supported on Oracle Linux. Virtualized infrastructure with Oracle VM and NetApp storage and data management solutions provides an integrated and seamless end user experience. Designed for maximum efficiency to allow for native NetApp deduplication and backup/recovery/cloning of VM’s or templates. Whether you are provisioning one or multiple server pools or dynamically re-provisioning storage for your virtual machines to meet business demands, with Oracle and NetApp, you have one single point-and-click console to rapidly and easily deploy a virtualized agile data infrastructure in minutes. So there you have it!  The third install of our Partner Spolight. Check out Part I and Part II of our Partner Spotlights from previous days if you've missed them. Remember to visit the Oracle Linux team at Oracle OpenWorld.

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• jquery is not working over local network [migrated]

  - by Kortyell Davis

  i have a fedora server running apache web server. the server is connected to a home network. i have a laptop connected to the same network. i can enter the ip address of my server into the browser of my laptop and pull up the index.html file located in the document root directory of the fedora home server. the index.html file contains jquery code. the jquery code only works when i open it locally in my browser (e.g. right click open with firefox), but when i attempt to view the webpage from my laptop the jquery code is not executed. the code is here below. <script type="text/javascript" src="jquery-1.8.2.js"></script> ' $(document).ready(function() { $('#form').hide(); $('input[type=text]').focus(function() { $(this).val(''); }); $('input[type=password]').focus(function() { $(this).val(''); }); $('.form').hide(); $('#log').click(function(){ $('#form').toggle(); }); $('#reg').click(function(){ $('.form').toggle(); }); });

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• how to convert bitmap image to CIELab image?

  - by Neal Davis

  Hello to stackoverflow members! This is my first post but I love reading the questions and answers on this forum! I'm using VS2008, CSharp, NET 3.5 and Windows XP Pro latest patches on this project. I am reading in a jpeg file to a bitmap image using CSharp in the following way: Bitmap bmp = new Bitmap("background.jpg"); Graphics g = Graphics.FromImage(bmp); I then write some text and logos on g using various DrawString and DrawImage commands. I then want to write this bitmap to a tiff file using the command: bmp.Save("final_artwork.tif", ImageFormat.Tiff); I don't know what the TIFF tags in the header of the final resultant TIFF file will be when you do bmp.Save as shown above? But what I want to produce is a TIFF image file with PHOTOMETRIC CIELab, BITSPERSAMPLE 8, SAMPLESPERPIXEL 3, FILLORDER MSB2LSB, ORIENTATION TOPLEFT, PLANARCONFIG CONTIG, and also uncompressed and singlestrip. Im fairly certain, at least I have not found anything about Microsoft API and CIELab, I can not convert the bitmap image to CIELab photometric and the other requirements using anything from the Microsoft API or .NET 3.5 environment - someone please correct if I am wrong. I have used libtiff in a project in the past but just to write a tiff file where the tiff image in memory was already in CIELab format and all the other requirements as noted per above. Im not certain libtiff can convert from my CSharp bitmap image, which is probably RGB photometric, to CIELab, 8 bps, and 3 spp? Maybe I can use OpenCVImage or Emgu CV or something similiar? So the main question is what is going to be the easiest way to get my final bitmap image as outlined above into a CIELab TIFF and also meeting the other requirements per above? Thanks for any suggestions and code fragments you can provide? Neal Davis

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• Navigating to nodes using xpath in flat structure

  - by James Berry

  I have an xml file in a flat structure. We do not control the format of this xml file, just have to deal with it. I've renamed the fields because they are highly domain specific and don't really make any difference to the problem. <attribute name="Title">Book A</attribute> <attribute name="Code">1</attribute> <attribute name="Author"> <value>James Berry</value> <value>John Smith</value> </attribute> <attribute name="Title">Book B</attribute> <attribute name="Code">2</attribute> <attribute name="Title">Book C</attribute> <attribute name="Code">3</attribute> <attribute name="Author"> <value>James Berry</value> </attribute> Key things to note: the file is not particularly hierarchical. Books are delimited by an occurance of an attribute element with name='Title'. But the name='Author' attribute node is optional. Is there a simple xpath statement I can use to find the authors of book 'n'? It is easy to identify the title of book 'n', but the authors value is optional. And you can't just take the following author because in the case of book 2, this would give the author for book 3. I have written a state machine to parse this as a series of elements, but I can't help thinking there would have been a way to directly get the results that I want.

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• Apache2 Enabling Includes module causes svn access to quit working

  - by Matthew Talbert

  I have dav_svn installed to provide http access to my svn repos. The url is directly under root, eg mywebsite.com/svn/individual-repo. This setup has been working great for some time. Now, I need SSI (server-side includes) for a project, so I enabled this module with a2enmod include. Now, tortoisesvn can't access the repo; it always returns a 301 permanent redirect. Some playing with it reveals I can access it in a browser if I'm sure to include the trailing / but it still doesn't work in TortoiseSVN. I've looked at all of the faq's for this problem with TortoiseSVN and apache, and none of them seem to apply to my problem. Anyone have any insight into this problem? I'm running Ubuntu 9.10 with Apache 2.2.12. The only change I've made to my configuration is to enable the includes mod. Here's my dav_svn conf: <Location /svn> DAV svn SVNParentPath /home/matthew/svn AuthType Basic AuthName "Subversion repository" AuthUserFile /etc/subversion/passwd Require valid-user </Location> and here's the relevant part of my virtual host conf: <Location /svn> SetHandler None Order allow,deny Allow from all </Location> Edit: OK, I've discovered that the real conflict is between the include module and basic authentication. That is, if I disable the include module, browse to the subversion repo, enter my user/pass for the basic authentication, I can browse it just fine. It even continues to work after I re-enable the include module. However, if I browse with another browser where I'm not already authenticated, then it no longer works.

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• Crazy problem with Nginx, PHP5-FPM on Ubuntu

  - by Emmanuel

  I've been trying to get a domain from shared hosting to my new VPS. Everything was working just 100% fine, and then all of a sudden rewrites stopped working, pictures that should work started returning 404s. I've got no idea why, but for some reason on my site: http://www.onlythebible.com/ only the home page works, all the other pages depend on rewrites which were working perfectly fine at one stage, but all of a sudden stopped working. Some of the pictures like this url: http://www.onlythebible.com/bgsPreview/Matthew-8.10.jpg which doesn't use a rewrite throws a 404? I almost certain it was nothing to do with the nginx configuration. I've got suspicions that it could be something to do with php5-fpm? The funny thing is, all of a sudden it started working again. And then an hour or so later it broke again and has now gone back to only displaying the home-page and all of the links (and some of the pictures) are just showing 404s. Does anyone have an idea of what the problem might be? I'm pretty new to the whole Linux VPS thing, but this just seems very strange. *edit Here's a line from the error log which might shed some light on the problem: 2011/02/06 03:04:59 [error] 2873#0: *220 open() "/usr/local/nginx/html/bgsPreview/Matthew-8.10.jpg" failed (2: No such file or directory), client: 114.77.115.211, server: onlythebible.com, request: "GET /bgsPreview/Matthew-8.10.jpg HTTP/1.1", host: "www.onlythebible.com", referrer: "http://www.onlythebible.com/" I wonder why it's trying to find the file in /usr/local/nginx/html instead of the proper root which is /var/www/ etc... Oh, and for some reason it's just started working again... for how long I don't know. Another thing that was a bit weird, is that the pages on my website are pulled from a database. But when I edited the database, the pages didn't change... It's almost like they've been cached or something.

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• Windows 7 / ATI CCC - Monitor limit?

  - by james.ingham

  Hi all, I have a Ati 4850 X2 and back in the days when Windows 7 was in beta, I had this running with 4 monitors (Crossfire off). Now I have come to set this up again, with a RTM version of Windows 7 and the latest ATI drivers and it seems I can only have two monitors on at one time. If I try and set the monitors up in Control Panel, it simply disables the non-primary monitor, and if I attempt to do it in CCC, I get the message "To extend the desktop, a desktop or display must be disabled." Does anyone know why this is and/or how to fix it? I've currently tried using the latest ATI drivers and the drivers (i think) I was using over a year ago when I had this setup. Thanks - James

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• Can't create PID file on MySQL server, permission denied

  - by James Barnhill

  The MySQL server won't start and is reporting the following error: /usr/local/mysql/bin/mysqld: Can't create/write to file '/usr/local/mysql/data/James-Barnhills-Mac-Pro.local.pid' (Errcode: 13) Can't start server: can't create PID file: Permission denied All the permissions are set recursively as: lrwxr-xr-x 1 _mysql wheel 27 Nov 22 09:25 mysql -> mysql-5.5.18-osx10.6-x86_64 but it won't start. I've tried reinstalling several times to no avail. I'm running as root on Mac OS, and MySQL has read, write, and execute permissions on the "data" folder.

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• Keyboard shortcut to quickly jump to the URL address field in Firefox...

  - by James Burton

  Hi, in Firefox I very often want to quickly enter a new URL in the address field. Therefore it would be very nice to be able to quickly jump to the URL address field with a keyboard shortcut! Today I must move my mouse and place the cursor in that field and also ensure that the current address is selected so I can overwrite it when entering the new URL. Very annoying! I'm sure I'm not the first one to have this need so there is probably a shortcut or an extension that does this already, but I cannot find that information! Thanks in advance, /James

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• Can Castle Monorail and ASP.NET MVC coexist in the same project?

  - by Matthew

  I have a large Monorail project that we have decided we are going to move over to ASP.NET MVC. Most of the underlying system will likely be reusable, but the Controllers will of course have to be rewritten, and proabably at least some of the views. It strikes me that a low risk avenue for this is gradually convert well defined sections of the system to MVC, and perhaps as MVCContrib Portable Areas. Does anyone know if there are any non-obvious gotchas that I am likely to run into with this approach? Thanks for your input, Matthew

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• What are good replacements for Microsoft Visio 2003?

  - by James

  I have been using Visio 2003 on Windows XP for generation of UML diagrams. I have encountered following problems so far: There is no way to generate/print the documentation written for class attributes/methods. No automatic code generation is supported I have already generated lot of diagrams and i discovered above problems at much later stage. Now i would like to overcome above by choosing another tool which is compatible with Visio file(.vsd) which saves time or redrawing all diagrams and also provides above features. Could you kindly suggest an alternative (visio compatible) tool ? (I have looked at a similar SU-question, but it does not suggest tools which provide solution to above problems. I am open to free as well as licensed tools, with priority to free :) ) Thanks, James

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