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  • Low level programming - what's in it for me?

    - by back2dos
    For years I have considered digging into what I consider "low level" languages. For me this means C and assembly. However I had no time for this yet, nor has it EVER been neccessary. Now because I don't see any neccessity arising, I feel like I should either just schedule some point in time when I will study the subject or drop the plan forever. My Position For the past 4 years I have focused on "web technologies", which may change, and I am an application developer, which is unlikely to change. In application development, I think usability is the most important thing. You write applications to be "consumed" by users. The more usable those applications are, the more value you have produced. In order to achieve good usability, I believe the following things are viable Good design: Well-thought-out features accessible through a well-thought-out user interface. Correctness: The best design isn't worth anything, if not implemented correctly. Flexibility: An application A should constantly evolve, so that its users need not switch to a different application B, that has new features, that A could implement. Applications addressing the same problem should not differ in features but in philosophy. Performance: Performance contributes to a good user experience. An application is ideally always responsive and performs its tasks reasonably fast (based on their frequency). The value of performance optimization beyond the point where it is noticeable by the user is questionable. I think low level programming is not going to help me with that, except for performance. But writing a whole app in a low level language for the sake of performance is premature optimization to me. My Question What could low level programming teach me, what other languages wouldn't teach me? Am I missing something, or is it just a skill, that is of very little use for application development? Please understand, that I am not questioning the value of C and assembly. It's just that in my everyday life, I am quite happy that all the intricacies of that world are abstracted away and managed for me (mostly by layers written in C/C++ and assembly themselves). I just don't see any concepts, that could be new to me, only details I would have to stuff my head with. So what's in it for me? My Conclusion Thanks to everyone for their answers. I must say, nobody really surprised me, but at least now I am quite sure I will drop this area of interest until any need for it arises. To my understanding, writing assembly these days for processors as they are in use in today's CPUs is not only unneccesarily complicated, but risks to result in poorer runtime performance than a C counterpart. Optimizing by hand is nearly impossible due to OOE, while you do not get all kinds of optimizations a compiler can do automatically. Also, the code is either portable, because it uses a small subset of available commands, or it is optimized, but then it probably works on one architecture only. Writing C is not nearly as neccessary anymore, as it was in the past. If I were to write an application in C, I would just as much use tested and established libraries and frameworks, that would spare me implementing string copy routines, sorting algorithms and other kind of stuff serving as exercise at university. My own code would execute faster at the cost of type safety. I am neither keen on reeinventing the wheel in the course of normal app development, nor trying to debug by looking at core dumps :D I am currently experimenting with languages and interpreters, so if there is anything I would like to publish, I suppose I'd port a working concept to C, although C++ might just as well do the trick. Again, thanks to everyone for your answers and your insight.

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  • ORA-4031 Troubleshooting

    - by [email protected]
      QUICKLINK: Note 396940.1 Troubleshooting and Diagnosing ORA-4031 Error Note 1087773.1 : ORA-4031 Diagnostics Tools [Video]   Have you observed an ORA-04031 error reported in your alert log? An ORA-4031 error is raised when memory is unavailable for use or reuse in the System Global Area (SGA).  The error message will indicate the memory pool getting errors and high level information about what kind of allocation failed and how much memory was unavailable.  The challenge with ORA-4031 analysis is that the error and associated trace is for a "victim" of the problem.   The failing code ran into the memory limitation, but in almost all cases it was not part of the root problem.    Looking for the best way to diagnose? When an ORA-4031 error occurs, a trace file is raised and noted in the alert log if the process experiencing the error is a background process.   User processes may experience errors without reports in the alert log or traces generated.   The V$SHARED_POOL_RESERVED view will show reports of misses for memory over the life of the database. Diagnostics scripts are available in Note 430473.1 to help in analysis of the problem.  There is also a training video on using and interpreting the script data Note 1087773.1. 11g DiagnosabilityStarting with Oracle Database 11g Release 1, the Diagnosability infrastructure was introduced which places traces and core files into a location controlled by the DIAGNOSTIC_DEST initialization parameter when an incident, such as an ORA-4031 occurs. For earlier versions, the trace file will be written to either USER_DUMP_DEST (if the error was caught in a user process) or BACKGROUND_DUMP_DEST (if the error was caught in a background process like PMON or SMON). The trace file contains vital information about what led to the error condition.  Note 443529.1 11g Quick Steps to Package and Send Critical Error Diagnostic Information to Support[Video]Oracle Configuration Manager (OCM)Oracle Configuration Manager (OCM) works with My Oracle Support to enable proactive support capability that helps you organize, collect and manage your Oracle configurations.Oracle Configuration Manager Quick Start GuideNote 548815.1: My Oracle Support Configuration Management FAQ Note 250434.1: BULLETIN: Learn More About My Oracle Support Configuration Manager    Common Causes/Solutions The ORA-4031 can occur for many different reasons.  Some possible causes are: SGA components too small for workload Auto-tuning issues Fragmentation due to application design Bug/leaks in memory allocationsFor more on the 4031 and how this affects the SGA, see Note 396940.1 Troubleshooting and Diagnosing ORA-4031 Error Because of the multiple potential causes, it is important to gather enough diagnostics so that an appropriate solution can be identified.  However, most commonly the cause is associated with configuration tuning.   Ensuring that MEMORY_TARGET or SGA_TARGET are large enough to accommodate workload can get around many scenarios.  The default trace associated with the error provides very high level information about the memory problem and the "victim" that ran into the issue.   The data in the default trace is not going to point to the root cause of the problem. When migrating from 9i to 10g and higher, it is necessary to increase the size of the Shared Pool due to changes in the basic design of the shared memory area. Note 270935.1 Shared pool sizing in 10gNOTE: Diagnostics on the errors should be investigated as close to the time of the error(s) as possible.  If you must restart a database, it is not feasible to diagnose the problem until the database has matured and/or started seeing the problems again. Note 801787.1 Common Cause for ORA-4031 in 10gR2, Excess "KGH: NO ACCESS" Memory Allocation ***For reference to the content in this blog, refer to Note.1088239.1 Master Note for Diagnosing ORA-4031 

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  • Data Connection Library in SharePoint Server 2010

    - by Wayne
    What is a Data Connection Library in SharePoint Server 2010? A Data Connection Library in Microsoft SharePoint Server 2010 is a library that can contain two kinds of data connections: an Office Data Connection (ODC) file or a Universal Data Connection (UDC) file. Microsoft InfoPath 2010 uses data connections that comply with the Universal Data Connection (UDC) file schema and typically have either a *.udcx or *.xml file name extension. Data sources described by these data connections are stored on the server and can be used in standard form templates and browser-enabled form templates. How to create a SharePoint Server Data Connection Library? 1. Browse to a SharePoint Server 2010 site on which you have at least Design permissions. If you are on the root site, create a new site before you continue with the next step. 2. On the Site Actions menu, click More Options. 3. On the Create page, click Library under Filter By, and then click Data Connection Library. 4. On the right side of the Create page, type a name for the library, and then click the Create button. 5. Copy the URL of the new data connection library. How to create a new data connection file in InfoPath? 1. Open InfoPath Designer 2010, click Blank Form, and then click Design Form. 2. On the Data tab, click Data Connections, and then click Add. 3. In the Data Connection Wizard, click Create a new connection to, click Receive data, and then click Next. 4. Click the kind of data source that you are connecting to, such as Database, Web service, or SharePoint library or list, and then click Next. 5. Complete the remaining steps in the Data Connection Wizard to configure your data connection, and then click Finish to return to the Data Connections dialog box. 6. In the Data Connections dialog box, click Convert to Connection File. 7. In the Convert Data Connection dialog box, enter the URL of the data connection library that you previously copied (delete "Forms/AllItems.aspx" and anything following it from the URL), enter a name for the data connection file at the end of the URL, and then click OK. It will take a few moments to convert and save the data connection file to the library. 8. Confirm that the data connection was converted successfully by examining the Details section of the Data Connections dialog box while the name of the converted data connection is selected. 9. Browse to the SharePoint data connection library, click the drop-down next to the name of the data connection, click Approve/Reject, click Approved, and then click OK. Take advantage of SharePoint Data Connection Library and other useful features of SharePoint family of products that include, SharePoint Foundation 2010, MOSS 2007 and free SharePoint templates or web parts.

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  • Is there a good [and modern] reason to not have static HTML pages with AJAX content , rather than generate pages?

    - by user1725
    Assumptions: We don't care about IE6, and Noscript users. Lets pretend we have the following design concept: All your pages are HTML/CSS that create the ascetics, layout, colours, general design related things. Lets pretend this basic code below is that: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html> <head> <link href="/example.css" rel="stylesheet" type="text/css"/> <script src="example.js" type="text/javascript"></script> <head> <body> <div class="left"> </div> <div class="mid"> </div> <div class="right"> </div> </body> </html> Which in theory should produce, with the right CSS, three vertical columns on the web page. Now, here's the root of the question, what are the serious advantages and/or disadvantages of loading the content of these columns (lets assume they are all indeed dynamic content, not static) via AJAX requests, or have the content pre-set with a scripting language? So for instance, we would have, in the AJAX example, lets asume jquery is used on-load: //Multiple http requests $("body > div.left").load("./script.php?content=news"); $("body > div.right").load("./script.php?content=blogs"); $("body > div.mid").load("./script.php?content=links"); OR--- //Single http request $.ajax({ url: './script.php?content=news|blogs|links', method: 'json', type: 'text', success: function (data) { $("body > div.left").html(data.news); $("body > div.right").html(data.blogs); $("body > div.mid").html(data.links); } }) Verses doing this: <body> <div class="left"> <?php echo function_returning_news(); ?> </div> <div class="mid"> <?php echo function_returning_blogs(); ?> </div> <div class="right"> <?php echo function_returning_links(); ?> </div> </body> I'm personally thinking right now that doing static HTML pages is a better method, my reasoning is: I've separated my data, logic, and presentation (ie, "MVC") code. I can make changes to one without others. Browser caches mean I'm just getting server load mostly for the content, not the presentation wrapped around it. I could turn my "script.php" into a more robust API for the website. But I'm not certain or clear that these are legitimately good reasons, and I'm not confidently aware of other issues that could happen, so I would like to know the pros-and-cons, so to speak.

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  • What Counts For a DBA: Imagination

    - by drsql
    "Imagination…One little spark, of inspiration… is at the heart, of all creation." – From the song "One Little Spark", by the Sherman Brothers I have a confession to make. Despite my great enthusiasm for databases and programming, it occurs to me that every database system I've ever worked on has been, in terms of its inputs and outputs, downright dull. Most have been glorified e-spreadsheets, many replacing manual systems built on actual spreadsheets. I've created a lot of database-driven software whose main job was to "count stuff"; phone calls, web visitors, payments, donations, pieces of equipment and so on. Sometimes, instead of counting stuff, the database recorded values from other stuff, such as data from sensors or networking devices. Yee hah! So how do we, as DBAs, maintain high standards and high spirits when we realize that so much of our work would fail to raise the pulse of even the most easily excitable soul? The answer lies in our imagination. To understand what I mean by this, consider a role that, in terms of its output, offers an extreme counterpoint to that of the DBA: the Disney Imagineer. Their job is to design Disney's Theme Parks, of which I'm a huge fan. To me this has always seemed like a fascinating and exciting job. What must an Imagineer do, every day, to inspire the feats of creativity that are so clearly evident in those spectacular rides and shows? Here, if ever there was one, is a role where "dull moments" must be rare indeed, surely? I wanted to find out, and so parted with a considerable sum of money for my wife and I to have lunch with one; I reasoned that if I found one small way to apply their secrets to my own career, it would be money well spent. Early in the conversation with our Imagineer (Cindy Cote), the job did indeed sound magical. However, as talk turned to management meetings, budget-wrangling and insane deadlines, I came to the strange realization that, in fact, her job was a lot more like mine than I would ever have guessed. Much like databases, all those spectacular Disney rides bring with them a vast array of complex plumbing, lighting, safety features, and all manner of other "boring bits", kept well out of sight of the end user, but vital for creating the desired experience; and, of course, it is these "boring bits" that take up much of the Imagineer's time. Naturally, there is still a vital part of their job that is spent testing out new ideas, putting themselves in the place of a park visitor, from a 9-year-old boy to a 90-year-old grandmother, and trying to imagine what experiences they'd like to have. It is these small, but vital, sparks of imagination and creativity that have the biggest impact. The real feat of a successful Imagineer is clearly to never to lose sight of this fact, in among all the rote tasks. It is the same for a DBA. Not matter how seemingly dull is the task at hand, try to put yourself in the shoes of the end user, and imagine how your input will affect the experience he or she will have with the database you're building, and how that may affect the world beyond the bits stored in your database. Then, despite the inevitable rush to be "done", find time to go the extra mile and hone the design so that it delivers something as close to that imagined experience as you can get. OK, our output still can't and won't reach the same spectacular heights as the "Journey into The Imagination" ride at EPCOT Theme Park in Orlando, where I first heard "One Little Spark". However, our imaginative sparks and efforts can, and will, make a difference to the user who now feels slightly more at home with a database application, or to the manager holding a report presented with enough clarity to drive an interesting decision or two. They are small victories, but worth having, and appreciated, or at least that's how I imagine it.

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  • SOA Community Newsletter May 2014

    - by JuergenKress
    Registration for the Fusion Middleware Summer Camps 2014 is open – Register asap for one of our bootcamps August 4th – 8th 2014 in Lisbon. Please read details and pre-requisitions careful before you register. We expect that like in the past, the conference will be booked out soon! If you can’t make it to Lisbon attend our SOA Suite 11c free on-demand Bootcamp or  Managing the Complexity of IoT online trainings. With more than 5000 customers, SOA Suite Achieves Significant Customer Adoption and Industry Recognition.Thanks to all our SOA Specialized partners for making our joins SOA customers successful! As a summary of the Industrial SOA series we published the Podcast Show Notes: SOA and Cloud - Where's This Relationship Going? Make sure you use the Oracle Demo Systems for your customer presentations. The demo systems are hosted by Oracle and include complete scenarios based on the latest Middleware version like the new B2B SOA Suite Demo System! For local presentations without fast internet use the SOA/BPM 11.1.1.7.1 Virtual Machine and Case Management Sample. At our SOA Community Workspace (SOA Community membership required) you can get new IoT presentations for Location Based Offers for Banking & Whitepaper and online Webcast & Utility presentation. In this newsletter you will find many articles about OSB: OSB 11g – A Hands-on Tutorial & Using Split-Joins in OSB Services for parallel processing of messages & OSB, Service Callouts and OQL & Working with Oracle Security Token Service. Thanks for sharing all the additional SOA articles within the community: How to configure Oracle SOA/BPM task auto release & Controlling BPEL process flow at runtime & Upgrading to Oracle SOA Suite 11g PS6 (11.1.1.7)? Do this. & BPEL and BPM's performance monitoring using DMS & SOA 11g - Create RESTful Service In Oracle SOA & Wrong timezone causes TopLink warning in SOA suite. Highlight of the BPM and ACM section is the IDC BPM vendor report. The new bundle Patch including the ACM UI is now available. If you want to learn more about ACM, get the ACM training material at our SOA Community Workspace (SOA Community membership required). A great demo for your next BPM presentation is the BPM iPad app. It’s simpleMobile BPM is Not An Option. It’s a Necessity. Thanks for sharing all the additional BPM articles within the community: BPM update adds Case Management Web Interface and REST APIs & Implementing deadline functionality with Oracle Adaptive Case Management & BPM 11g Timeout Heuristics & Humantask Assignment: Names and Expressions Assignment via Rules. In our last section Architecture, it is all about design. Usability is a key factor for customer satisfaction, worth to spend some time and read the Simplified User Experience Design Patterns eBook. Great blueprint for your project! See you in Lisbon! To read the newsletter please visit www.tinyurl.com/soaNewsMay2014 (OPN Account required) To become a member of the SOA Partner Community please register at http://www.oracle.com/goto/emea/soa (OPN account required) If you need support with your account please contact the Oracle Partner Business Center. Blog Twitter LinkedIn Facebook Wiki Mix Forum Technorati Tags: newsletter,SOA Community newsletter,SOA Community,Oracle,OPN,Jürgen Kress

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  • When to use Aspect Oriented Architecture (AOA/AOD)

    When is it appropriate to use aspect oriented architecture? I think the only honest answer to this question is that it depends on the context for which the question is being asked. There really are no hard and fast rules regarding the selection of an architectural model(s) for a project because each model provides good and bad benefits. Every system is built with a unique requirements and constraints. This context will dictate when to use one type of architecture over another or in conjunction with others. To me aspect oriented architecture models should be a sub-phase in the architectural modeling and design process especially when creating enterprise level models. Personally, I like to use this approach to create a base architectural model that is defined by non-functional requirements and system quality attributes.   This general model can then be used as a starting point for additional models because it is targets all of the business key quality attributes required by the system.Aspect oriented architecture is a method for modeling non-functional requirements and quality attributes of a system known as aspects. These models do not deal directly with specific functionality. They do categorize functionality of the system. This approach allows a system to be created with a strong emphasis on separating system concerns into individual components. These cross cutting components enables a systems to create with compartmentalization in regards to non-functional requirements or quality attributes.  This allows for the reduction in code because an each component maintains an aspect of a system that can be called by other aspects. This approach also allows for a much cleaner and smaller code base during the implementation and support of a system. Additionally, enabling developers to develop systems based on aspect-oriented design projects will be completed faster and will be more reliable because existing components can be shared across a system; thus, the time needed to create and test the functionality is reduced.   Example of an effective use of Aspect Oriented ArchitectureIn my experiences, aspect oriented architecture can be very effective with large or more complex systems. Typically, these types of systems have a large number of concerns so the act of defining them is very beneficial for reducing the system’s complexity because components can be developed to address each concern while exposing functionality to the other system components. The benefits to using the aspect oriented approach as the starting point for a system is that it promotes communication between IT and the business due to the fact that the aspect oriented models are quality attributes focused so not much technical understanding is needed to understand the model.An example of this can be in developing a new intranet website. Common Intranet Concerns: Error Handling Security Logging Notifications Database connectivity Example of a not as effective use of Aspect Oriented ArchitectureAgain in my experiences, aspect oriented architecture is not as effective with small or less complex systems in comparison.  There is no need to model concerns for a system that has a limited amount of them because the added overhead would not be justified for the actual benefits of creating the aspect oriented architecture model.  Furthermore, these types of projects typically have a reduced time schedule and a limited budget.  The creation of the Aspect oriented models would increase the overhead of a project and thus increase the time needed to implement the system. An example of this is seen by creating a small application to poll a network share for new files and then FTP them to a new location.  The two primary concerns for this project is to monitor a network drive and FTP files to a new location.  There is no need to create an aspect model for this system because there will never be a need to share functionality amongst either of these concerns.  To add to my point, this system is so small that it could be created with just a few classes so the added layer of componentizing the concerns would be complete overkill for this situation. References:Brichau, Johan; D'Hondt, Theo. (2006) Aspect-Oriented Software Development (AOSD) - An Introduction. Retreived from: http://www.info.ucl.ac.be/~jbrichau/courses/introductionToAOSD.pdf

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  • Day 5 - Tada! My Game Menu Screen Graphics

    - by dapostolov
    So, tonight I took some time to mash up some graphics for my game menu screen. My artistic talent sucks...but here goes nothing...voila, my menu screen!! The Menu Screen The screen above is displaying 4 sprites, even though it looks like maybe 7... I guess one of the first things for me to test in the future is ... is it more memory efficient (and better frame rate) to draw one big background image OR tp paint the screen black, and place each sprite in set locations? To display the 4 sprites above, I borrowed my code from yesterday ... I know, tacky, but...I wanted to see it, feel it. Do you feel it? FEEL IT! (homer voice & shakes fist) Note: the menu items won't scale properly as it stands with this code, well pretty much they do nothing except look pretty... Paint.Net & Google Fun So how did I create that image above? Well, to create the background and 3 menu items I used Paint.Net. Basically, I scoured Google images for: a stone doorway, a stone pillar, an old book, a wizards hat, and...that's it pretty much it! I'll let you type in those searches and see if you can locate the images I used. I know, bad developer...but I figured since I modified the images considerably it doesn't count...well for a personal project it shouldn't count...*shrug* Anyhow, I extracted each key assest I wanted from each image and applied lots of matting, blurring, color changes, glow effects and such. Then, using my vivid imagination I placed / composed each of the layered assets into the mashed up the "scene" above. Pretty cool, eh? Hey, did you know, the cool mist effect is actually a fire rendition in Paint.net? I set it to black & white with opacity set next to nothing. I'm also very proud of the yellow "light" in the stone doorway. I drew that in and then applied gausian blur to it to give it the effect of light creeping out around the door and into the room...heheh. So did I achieve the dark, mysterious ritual as I stated in my design doc? I think I had a great stab at it! Maybe down the road I can get a real artist to crank out some quality graphics for the game... =) So, What's Next? Well, I don't have that animated brazier yet...however, I thought it would be even cooler if I can get that door pulsing that yellow light and it would be extremely cool to have the smoke / mist moving across the screen! Make the creative ideas stop!! (clutches head) haha! I'm having great fun working on this project =) I recommend others giving something like this a try, it's really fulfilling. OK. Tomorrow... I think I'm going to start creating some game / menu objects as per the design doc, maybe even get a custom mouse cursor up on the screen and handle a couple of mouse events, and lastly, maybe a feature to toggle a framerate display... D.

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  • Removing Barriers to Create Effective Data Models

    After years of creating and maintaining data models, I have started to notice common barriers that decrease the accuracy and usefulness of models. In my opinion, the main causes of these barriers are the lack of knowledge and communication from within a company. The lack of knowledge in regards to data models or data modeling can take many forms. Company Culture Knowledge Whether documented or undocumented, existing business rules of a company can affect how data is modeled. For example, if a company only allows 1 assigned person per customer to be able to manipulate a customer’s record then then a data model that includes an associated table that joins customers and employee’s would be unneeded because that would allow for the possibility of multiple employees to handle a customer because of the potential for a many to many relationship between Customers and Employees. Technical Knowledge Depending on the data modeler’s proficiency in modeling data they can inadvertently cause issues and/or complications with a design without even noticing. It is important that companies share data modeling responsibilities so that the models are developed from multiple perspectives of a system, company and the original problem.  In addition, the tools that a company selects to create data models can also affect the accuracy of the model if designer are not familiar with the tools or the tools are too complex to use for the designer. Existing System Knowledge In order for a data modeler to model data for an existing system so that new changes can be applied to a system then they need to at least know the basic concepts of a system so that they can work within it. This will promote reusability of data and prevent the chance of duplicating data. Project Knowledge This should be pretty obvious, but it is very hard to create an accurate data model without knowing what data needs to be modeled. I have always found it strange that I have been asked to start modeling data prior to a client formalizing any requirements. Usually when this happens I have to make several iterations to a model, and the client still does not know exactly what they want.  In addition additional issues can arise when certain stakeholders of a project are not consulted prior to the design or after the project is over because it can cause miss understandings and confusion by the end user as well as possibly not solving the original problem for which a project is intended to solve. One common thread between each type of knowledge is that they can all be avoided through the use of good communication. For example, if a modeler is new to a company then they should ask older employees about any business specific rules that may be documented or undocumented that must be applied to projects in general. Furthermore, if a modeler is not really familiar with a specific data modeling software then they need to speak up and ask for help form other employees or their manager. This will not only help the modeler in the project, but also help them in future projects that they do for the company. Additionally, if a project is not clearly defined prior to a data modeler being assigned the modeling project then it is their responsibility to communicate with the other stakeholders to clarify any part of a project that is unclear so that the data model that is created is accurately aligned with a project.

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  • The Power to Control Power

    - by speakjava
    I'm currently working on a number of projects using embedded Java on the Raspberry Pi and Beagle Board.  These are nice and small, so don't take up much room on my desk as you can see in this picture. As you can also see I have power and network connections emerging from under my desk.  One of the (admittedly very minor) drawbacks of these systems is that they have no on/off switch.  Instead you insert or remove the power connector (USB for the RasPi, a barrel connector for the Beagle).  For the Beagle Board this can potentially be an issue; with the micro-SD card located right next to the connector it has been known for people to eject the card when trying to power off the board, which can be quite serious for the hardware. The alternative is obviously to leave the boards plugged in and then disconnect the power from the outlet.  Simple enough, but a picture of underneath my desk shows that this is not the ideal situation either. This made me think that it would be great if I could have some way of controlling a mains voltage outlet using a remote switch or, even better, from software via a USB connector.  A search revealed not much that fit my requirements, and anything that was close seemed very expensive.  Obviously the only way to solve this was to build my own.Here's my solution.  I decided my system would support both control mechanisms (remote physical switch and USB computer control) and be modular in its design for optimum flexibility.  I did a bit of searching and found a company in Hong Kong that were offering solid state relays for 99p plus shipping (£2.99, but still made the total price very reasonable).  These would handle up to 380V AC on the output side so more than capable of coping with the UK 240V supply.  The other great thing was that being solid state, the input would work with a range of 3-32V and required a very low current of 7.5mA at 12V.  For the USB control an Arduino board seemed the obvious low-cost and simple choice.  Given the current requirments of the relay, the Arduino would not require the additional power supply and could be powered just from the USB.Having secured the relays I popped down to Homebase for a couple of 13A sockets, RS for a box and an Arduino and Maplin for a toggle switch.  The circuit is pretty straightforward, as shown in the diagram (only one output is shown to make it as simple as possible).  Originally I used a 2 pole toggle switch to select the remote switch or USB control by switching the negative connections of the low voltage side.  Unfortunately, the resistance between the digital pins of the Arduino board was not high enough, so when using one of the remote switches it would turn on both of the outlets.  I changed to a 4 pole switch and isolated both positive and negative connections. IMPORTANT NOTE: If you want to follow my design, please be aware that it requires working with mains voltages.  If you are at all concerned with your ability to do this please consult a qualified electrician to help you.It was a tight fit, especially getting the Arduino in, but in the end it all worked.  The completed box is shown in the photos. The remote switch was pretty simple just requiring the squeezing of two rocker switches and a 9V battery into the small RS supplied box.  I repurposed a standard stereo cable with phono plugs to connect the switch box to the mains outlets.  I chopped off one set of plugs and wired it to the rocker switches.  The photo shows the RasPi and the Beagle board now controllable from the switch box on the desk. I've tested the Arduino side of things and this works fine.  Next I need to write some software to provide an interface for control of the outlets.  I'm thinking a JavaFX GUI would be in keeping with the total overkill style of this project.

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  • C++ property system interface for game editors (reflection system)

    - by Cristopher Ismael Sosa Abarca
    I have designed an reusable game engine for an project, and their functionality is like this: Is a completely scripted game engine instead of the usual scripting languages as Lua or Python, this uses Runtime-Compiled C++, and an modified version of Cistron (an component-based programming framework).to be compatible with Runtime-Compiled C++ and so on. Using the typical GameObject and Component classes of the Component-based design pattern, is serializable via JSON, BSON or Binary useful for selecting which objects will be loaded the next time. The main problem: We want to use our custom GameObjects and their components properties in our level editor, before used hardcoded functions to access GameObject base class virtual functions from the derived ones, if do you want to modify an property specifically from that class you need inside into the code, this situation happens too with the derived classes of Component class, in little projects there's no problem but for larger projects becomes tedious, lengthy and error-prone. I've researched a lot to find a solution without luck, i tried with the Ogitor's property system (since our engine is Ogre-based) but we find it inappropiate for the component-based design and it's limited only for the Ogre classes and can lead to performance overhead, and we tried some code we find in the Internet we tested it and worked a little but we considered the macro and lambda abuse too horrible take a look (some code omitted): IWE_IMPLEMENT_PROP_BEGIN(CBaseEntity) IWE_PROP_LEVEL_BEGIN("Editor"); IWE_PROP_INT_S("Id", "Internal id", m_nEntID, [](int n) {}, true); IWE_PROP_LEVEL_END(); IWE_PROP_LEVEL_BEGIN("Entity"); IWE_PROP_STRING_S("Mesh", "Mesh used for this entity", m_pModelName, [pInst](const std::string& sModelName) { pInst->m_stackMemUndoType.push(ENT_MEM_MESH); pInst->m_stackMemUndoStr.push(pInst->getModelName()); pInst->setModel(sModelName, false); pInst->saveState(); }, false); IWE_PROP_VECTOR3_S("Position", m_vecPosition, [pInst](float fX, float fY, float fZ) { pInst->m_stackMemUndoType.push(ENT_MEM_POSITION); pInst->m_stackMemUndoVec3.push(pInst->getPosition()); pInst->saveState(); pInst->m_vecPosition.Get()[0] = fX; pInst->m_vecPosition.Get()[1] = fY; pInst->m_vecPosition.Get()[2] = fZ; pInst->setPosition(pInst->m_vecPosition); }, false); IWE_PROP_QUATERNION_S("Orientation (Quat)", m_quatOrientation, [pInst](float fW, float fX, float fY, float fZ) { pInst->m_stackMemUndoType.push(ENT_MEM_ROTATE); pInst->m_stackMemUndoQuat.push(pInst->getOrientation()); pInst->saveState(); pInst->m_quatOrientation.Get()[0] = fW; pInst->m_quatOrientation.Get()[1] = fX; pInst->m_quatOrientation.Get()[2] = fY; pInst->m_quatOrientation.Get()[3] = fZ; pInst->setOrientation(pInst->m_quatOrientation); }, false); IWE_PROP_LEVEL_END(); IWE_IMPLEMENT_PROP_END() We are finding an simplified way to this, without leading confusing the programmers, (will be released to the public) i find ways to achieve this but they are only available for the common scripting as Lua or editors using C#. also too portable, we can write "wrappers" for different GUI toolkits as Qt or GTK, also i'm thinking to using Boost.Wave to get additional macro functionality without creating my own compiler. The properties designed to use in the editor they are removed in the game since the save file contains their data and loads it using an simple 'load' function to reduce unnecessary code bloat may will be useful if some GameObject property wants to be hidden instead. In summary, there's a way to implement an reflection(property) system for a level editor based in properties from derived classes? Also we can use C++11 and Boost (restricted only to Wave and PropertyTree)

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  • ArchBeat Link-o-Rama Top 10 for October 2012

    - by Bob Rhubart
    The Top 10 most popular items shared on the OTN ArchBeat Facebook Page for October 2012. OAM/OVD JVM Tuning | @FusionSecExpert Vinay from the Oracle Fusion Middleware Architecture Group (known as the A-Team) shares a process for analyzing and improving performance in Oracle Virtual Directory and Oracle Access Manager. SOA Galore: New Books for Technical Eyes Only Shake up up your technical skills with this trio of new technical books from community members covering SOA and BPM. Clustering ODI11g for High-Availability Part 1: Introduction and Architecture | Richard Yeardley "JEE agents can be deployed alongside, or instead of, standalone agents," says Rittman Meade's Richard Yeardley. "But there is one key advantage in using JEE agents and WebLogic – when you deploy JEE agents as part of a WebLogic cluster they can be configured together to form a high availability cluster." Learn more in Yeardley's extensive post. Solving Big Problems in Our 21st Century Information Society | Irving Wladawsky-Berger "I believe that the kind of extensive collaboration between the private sector, academia and government represented by the Internet revolution will be the way we will generally tackle big problems in the 21st century. Just as with the Internet, governments have a major role to play as the catalyst for many of the big projects that the private sector will then take forward and exploit. The need for high bandwidth, robust national broadband infrastructures is but one such example." -- Irving Wladawsky-Berger Eventually, 90% of tech budgets will be outside IT departments | ZDNet Another interesting post from ZDNet blogger Joe McKendrick about changing roles in IT. ADF Mobile - Login Functionality | Andrejus Baranovskis "The new ADF Mobile approach with native deployment is cool when you want to access phone functionality (camera, email, sms and etc.), also when you want to build mobile applications with advanced UI," reports Oracle ACE Director Andrejus Baranovskis. Podcast: Are You Future Proof? - Part 2 In Part 2, practicing architects and Oracle ACE Directors Ron Batra (AT&T), Basheer Khan (Innowave Technology), and Ronald van Luttikhuizen (Vennster) discuss re-tooling one’s skill set to reflect changes in enterprise IT, including the knowledge to steer stakeholders around the hype to what's truly valuable. ADF Mobile Custom Javascript — iFrame Injection | John Brunswick The ADF Mobile Framework provides a range of out of the box components to add within your AMX pages, according to John Brunswick. But what happens when "an out of the box component does not directly fulfill your development need? What options are available to extend your application interface?" John has an answer. Oracle Solaris 11.1 update focuses on database integration, cloud | Mark Fontecchio TechTarget editor Mark Fontecchio reports on the recent Oracle Solaris 11.1 release, with comments from IDC's Al Gillen. Architects Matter: Making sense of the people who make sense of enterprise IT Why do architects matter? Oracle Enterprise Architect Eric Stephens suggests that you ask yourself this question the next time you take the elevator to the Oracle offices on the 45th floor of the Willis Tower in Chicago, Illinois (or any other skyscraper, for that matter). If you had to take the stairs to get to those offices, who would you blame? "You get the picture," he says. "Architecture is essential for any necessarily complex structure, be it a building or an enterprise." (Read the article) Thought for the Day "I will contend that conceptual integrity is the most important consideration in system design. It is better to have a system omit certain anomalous features and improvements, but to reflect one set of design ideas, than to have one that contains many good but independent and uncoordinated ideas." — Frederick P. Brooks Source: SoftwareQuotes.com

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  • Scenarios for Throwing Exceptions

    - by Joe Mayo
    I recently came across a situation where someone had an opinion that differed from mine of when an exception should be thrown. This particular case was an issue opened on LINQ to Twitter for an Exception on EndSession.  The premise of the issue was that the poster didn’t feel an exception should be raised, regardless of authentication status.  As first, this sounded like a valid point.  However, I went back to review my code and decided not to make any changes. Here's my rationale: 1. The exception doesn’t occur if the user is authenticated when EndAccountSession is called. 2. The exception does occur if the user is not authenticated when EndAccountSession is called. 3. The exception represents the fact that EndAccountSession is not able to fulfill its intended purpose - to end the session.  If a session never existed, then it would not be possible to perform the requested action.  Therefore, an exception is appropriate. To help illustrate how to handle this situation, I've modified the following code in Program.cs in the LinqToTwitterDemo project to illustrate the situation: static void EndSession(ITwitterAuthorizer auth) { using (var twitterCtx = new TwitterContext(auth, "https://api.twitter.com/1/", "https://search.twitter.com/")) { try { //Log twitterCtx.Log = Console.Out; var status = twitterCtx.EndAccountSession(); Console.WriteLine("Request: {0}, Error: {1}" , status.Request , status.Error); } catch (TwitterQueryException tqe) { var webEx = tqe.InnerException as WebException; if (webEx != null) { var webResp = webEx.Response as HttpWebResponse; if (webResp != null && webResp.StatusCode == HttpStatusCode.Unauthorized) Console.WriteLine("Twitter didn't recognize you as having been logged in. Therefore, your request to end session is illogical.\n"); } var status = tqe.Response; Console.WriteLine("Request: {0}, Error: {1}" , status.Request , status.Error); } } } As expected, LINQ to Twitter wraps the exception in a TwitterQueryException as the InnerException.  The TwitterQueryException serves a very useful purpose through it's Response property.  Notice in the example above that the response has Request and Error proprieties.  These properties correspond to the information that Twitter returns as part of it's response payload.  This is often useful while debugging to help you understand why Twitter was unable to perform the  requested action.  Other times, it's cryptic, but that's another story.  At least you have some way of knowing in your code how to anticipate and handle these situations, along with having extra information to debug with. To sum things up, there are two points to make: when and why an exception should be raised and when to wrap and re-throw an exception in a custom exception type. I felt it was necessary to allow the exception to be raised because the called method was unable to perform the task it was designed for.  I also felt that it is inappropriate for a general library to do anything with exceptions because that could potentially hide a problem from the caller.  A related point is that it should be the exclusive decision of the application that uses the library on what to do with an exception.  Another aspect of this situation is that I wrapped the exception in a custom exception and re-threw.  This is a tough call because I don’t want to hide any stack trace information.  However, the need to make the exception more meaningful by including vital information returned from Twitter swayed me in the direction to design an interface that was as helpful as possible to library consumers.  As shown in the code above, you can dig into the exception and pull out a lot of good information, such as the fact that the underlying HTTP response was a 401 Unauthorized.  In all, trade-offs are seldom perfect for all cases, but combining the fact that the method was unable to perform its intended function, this is a library, and the extra information can be more helpful, it seemed to be the better design. @JoeMayo

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  • What common interface would be appropriate for these game object classes?

    - by Jefffrey
    Question A component based system's goal is to solve the problems that derives from inheritance: for example the fact that some parts of the code (that are called components) are reused by very different classes that, hypothetically, would lie in a very different branch of the inheritance tree. That's a very nice concept, but I've found out that CBS is often hard to accomplish without using ugly hacks. Implementations of this system are often far from clean. But I don't want to discuss this any further. My question is: how can I solve the same problems a CBS try to solve with a very clean interface? (possibly with examples, there are a lot of abstract talks about the "perfect" design already). Context Here's an example I was going for before realizing I was just reinventing inheritance again: class Human { public: Position position; Movement movement; Sprite sprite; // other human specific components }; class Zombie { Position position; Movement movement; Sprite sprite; // other zombie specific components }; After writing that I realized I needed an interface, otherwise I would have needed N containers for N different types of objects (or to use boost::variant to gather them all together). So I've thought of polymorphism (move what systems do in a CBS design into class specific functions): class Entity { public: virtual void on_event(Event) {} // not pure virtual on purpose virtual void on_update(World) {} virtual void on_draw(Window) {} }; class Human : public Entity { private: Position position; Movement movement; Sprite sprite; public: virtual void on_event(Event) { ... } virtual void on_update(World) { ... } virtual void on_draw(Window) { ... } }; class Zombie : public Entity { private: Position position; Movement movement; Sprite sprite; public: virtual void on_event(Event) { ... } virtual void on_update(World) { ... } virtual void on_draw(Window) { ... } }; Which was nice, except for the fact that now the outside world would not even be able to know where a Human is positioned (it does not have access to its position member). That would be useful to track the player position for collision detection or if on_update the Zombie would want to track down its nearest human to move towards him. So I added const Position& get_position() const; to both the Zombie and Human classes. And then I realized that both functionality were shared, so it should have gone to the common base class: Entity. Do you notice anything? Yes, with that methodology I would have a god Entity class full of common functionality (which is the thing I was trying to avoid in the first place). Meaning of "hacks" in the implementation I'm referring to I'm talking about the implementations that defines Entities as simple IDs to which components are dynamically attached. Their implementation can vary from C-stylish: int last_id; Position* positions[MAX_ENTITIES]; Movement* movements[MAX_ENTITIES]; Where positions[i], movements[i], component[i], ... make up the entity. Or to more C++-style: int last_id; std::map<int, Position> positions; std::map<int, Movement> movements; From which systems can detect if an entity/id can have attached components.

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  • When things go awry

    - by Phil Factor
    The moment the Entrepreneur opened his mouth on prime-time national TV, spelled out the URL and waxed big on how exciting ‘his’ new website was, I knew I was in for a busy night. I’d designed and built it. All at once, half a million people tried to log into the website. Although all my stress-testing paid off, I have to admit that the network locked up tight long before there was any danger of a database or website problem. Soon afterwards, the Entrepreneur and the Big Boss were there in the autopsy meeting. We picked through all our systems in detail to see how they’d borne the unexpected strain. Mercifully, in view of the sour mood of the Big Boss, it turned out that the only thing we could have done better was buy a bigger pipe to and from the internet. We’d specified that ‘big pipe’ when designing the system. The Big Boss had then railed at the cost and so we’d subsequently compromised. I felt that my design decisions were vindicated. The Big Boss brooded for a while. Then he made the significant comment: “What really ****** me off is the fact that, for ten minutes, we couldn’t take people’s money.” At that point I stopped feeling smug. Had the internet connection been better, the system would have reached its limit and failed rather precipitously, and that wasn’t what he wanted. Then it occurred to me that what had gummed up the connection was all those images on the site, that had made it so impressive for the visitors. If there had been a way to automatically pare down the site to the bare essentials under stress… Hmm. I began to consider disaster-recovery in the broadest sense – maintaining a service in spite of unusual or unexpected events. What he said makes a lot of sense: sacrifice whatever isn’t essential to keep the core service running when we approach the capacity limits. Maybe in IT we should borrow (or revive) the business concept of the ‘Skeleton service’, maintaining only the priority parts under stress, using a process that is well-prepared and carefully rehearsed. How might this work? Whatever the event we have to prepare for, it is all about understanding the priorities; knowing what one can dispense with when the going gets tough. In the event of database disaster, it’s much faster to deploy a skeletal system with only the essential data than to restore the entire system, though there would have to be a reconciliation process to update the revived database retrospectively, once the emergency was over. It isn’t just the database that could be designed for resilience. One could prepare for unusually high traffic in a website by designing a system that degraded gradually to a ‘skeletal’ site, one that maintained the commercial essentials without fat images, JavaScript libraries and razzmatazz. This is all what the Big Boss scathingly called ‘a mere technicality’. It seems to me that what is needed first is a culture of application and database design which acknowledges that we live in a very imperfect world, and react accordingly when things go awry.

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  • Customer Loyalty vs. Customer Engagement: Who Cares?

    - by Jeb Dasteel-Oracle
    Have you read the recent Forbes OracleVoice blog titled Customer Loyalty is Dead. Long Live Engagement!? If you haven’t, take a look. This article prompted lots of conversation in the social realm. Many who read the article voiced their reactions to the headline and now I’m jumping in to add my view. Normal 0 false false false EN-US X-NONE X-NONE Customer loyalty is still key. It’s the effect and engagement is the cause. We at least know that to be true for our customers. We are in an age where customers are demanding to be heard. We need them to be actively involved – or engaged – as well. Greater levels of customer engagement, properly targeted, positively correlate with satisfaction. Our data has shown us this over and over. Satisfied customers are more loyal and more willing to vocalize their satisfaction through referencing, and are more likely to purchase again, all of which in turn drives incremental revenue – from the customer doing the referencing AND the customer on the receiving end of that reference. Turning this around completely, if we begin to see the level of a customer’s engagement start to wane, this is an indicator that their satisfaction, loyalty, and future revenue are likely at risk. At Oracle, we’ve put in place many programs to target, encourage, and then track engagement, allowing us to measure engagement as a determinant of loyalty. Some of these programs include our Key Accounts, solution design and architectural, Executive Sponsorship, as well as executive advisory boards. Specific programs allow us to engage specific contacts within specific customer organizations (based on role) and then systematically track their engagement activities over time, along side of tracking customer satisfaction, loyalty, referenceability, and incremental revenue contribution. Continuous measurement of engagement allows us to better understand customer views of what it means to partner with a provider and adjust program participation to better meet the needs of the partnership. We can also track across customer segments, and design new programs that are even more effective than the ones we have in place today. In case you missed any of my previous Forbes articles, I’ve included links below for easy access. Award-Winning Companies Put Customers First The Power of Peer Networks: 5 Reasons to Get (and Stay) Involved Technology At Work: Traveling In Style Customer Central: 8 Strategies for Putting Customers at the Core of Your Business Technology at Work: Five Companies Doing IT Right /* 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-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; 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-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}

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  • XamlParseException using Silverlight Toolkit control in Expression Blend

    - by Dan Auclair
    I am having a strange issue opening up my UserControl in Expression Blend when using a Silverlight Toolkit control. My UserControl uses the toolkit's ListBoxDragDropTarget as follows: <controlsToolkit:ListBoxDragDropTarget mswindows:DragDrop.AllowDrop="True" HorizontalContentAlignment="Stretch" VerticalContentAlignment="Stretch"> <ListBox ItemsSource="{Binding MyItemControls}" ScrollViewer.HorizontalScrollBarVisibility="Disabled"> <ListBox.ItemsPanel> <ItemsPanelTemplate> <controlsToolkit:WrapPanel/> </ItemsPanelTemplate> </ListBox.ItemsPanel> </ListBox> </controlsToolkit:ListBoxDragDropTarget> Everything works as expected at runtime and looks fine in Visual Studio 2008. However, when I try to open my UserControl in Blend I get XamlParseException: [Line: 0 Position: 0] and I can not see anything in the design view. More specifically Blend complains: The element "ListBoxDragDropTarget" could not be displayed because of a problem with System.Windows.Controls.ListBoxDragDropTarget: TargetType mismatch. My silverlight application is referencing System.Windows.Controls.Toolkit from the Nov. 2009 toolkit release, and I've made sure to include these namespace declarations for the ListBoxDragDropTarget: xmlns:controlsToolkit="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.Toolkit" xmlns:mswindows="clr-namespace:Microsoft.Windows;assembly=System.Windows.Controls.Toolkit" If I comment out the ListBoxDragDropTarget control wrapper and just leave the ListBox I can see everything fine in the design view without errors. Furthermore, I realized this is happening with a variety of Silverlight Toolkit controls because if I comment out ListBoxDragDropTarget and replace it with <controlsToolkit:BusyIndicator /> the same exact error occurs in Blend. What is even weirder is that if I start a brand new silverlight application in blend I can add these toolkit elements without any kind of error, so it seems like something dumb that is happening with my project references to the toolkit assemblies. I'm pretty sure this has something to do with loading the default styles for the toolkit controls from its generic.xaml, since the error has to do with the TargetType and Blend is probably trying to load up the default styles. Has anyone encountered this issue before or have any ideas as to what may be my problem?

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  • How to properly test for constraint violation in hibernate?

    - by Cesar
    I'm trying to test Hibernate mappings, specifically a unique constraint. My POJO is mapped as follows: <property name="name" type="string" unique="true" not-null="true" /> What I want to do is to test that I can't persist two entities with the same name: @Test(expected=ConstraintViolationException.class) public void testPersistTwoExpertiseAreasWithTheSameNameIsNotAllowed(){ ExpertiseArea ea = new ExpertiseArea("Design"); ExpertiseArea otherEA = new ExpertiseArea("Design"); ead.setSession(getSessionFactory().getCurrentSession()); ead.getSession().beginTransaction(); ead.makePersistent(ea); ead.makePersistent(otherEA); ead.getSession().getTransaction().commit(); } On commiting the current transaction, I can see in the logs that a ConstraintViolationException is thrown: 16:08:47,571 DEBUG SQL:111 - insert into ExpertiseArea (VERSION, name, id) values (?, ?, ?) Hibernate: insert into ExpertiseArea (VERSION, name, id) values (?, ?, ?) 16:08:47,571 DEBUG SQL:111 - insert into ExpertiseArea (VERSION, name, id) values (?, ?, ?) Hibernate: insert into ExpertiseArea (VERSION, name, id) values (?, ?, ?) 16:08:47,572 WARN JDBCExceptionReporter:100 - SQL Error: -104, SQLState: 23505 16:08:47,572 ERROR JDBCExceptionReporter:101 - integrity constraint violation: unique constraint or index violation; SYS_CT_10036 table: EXPERTISEAREA 16:08:47,573 ERROR AbstractFlushingEventListener:324 - Could not synchronize database state with session org.hibernate.exception.ConstraintViolationException: Could not execute JDBC batch update So I would expect the test to pass, since the expected ConstraintViolationException is thrown. However, the test never completes (neither pass nor fails) and I have to manually kill the test runner. What's the correct way to test this?

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  • How to achieve "Blendability" when using DataServiceCollection in my ViewModel

    - by andlju
    I'm looking at using oData endpoints in my Silverlight client. Naturally, I'm doing MVVM and I want the project to be nice and "Blendable" (i.e. I must be able to cleanly use static data instead of the oData endpoints when in design mode.) Now to the problem. I'd like to use the DataServiceCollection in my ViewModels, since it allows for nice bindable collections without having to worry too much with BeginExecute/EndExecute etc. Now, let's look at some code. My Model interface looks like this: public interface ITasksModel { IQueryable<Task> Tasks { get; } } The oData endpoint implementation of that interface: public class TasksModel : ITasksModel { Uri svcUri = new Uri("http://localhost:2404/Services/TasksDataService.svc"); TaskModelContainer _container; public TasksModel() { _container = new TaskModelContainer(svcUri); } public IQueryable<Task> Tasks { get { return _container.TaskSet; } } } And the "Blendable" design-time implementation: public class DesignModeTasksModel : ITasksModel { private List<Task> _taskCollection = new List<Task>(); public DesignModeTasksModel() { _taskCollection.Add(new Task() { Id = 1, Title = "Task 1" }); _taskCollection.Add(new Task() { Id = 2, Title = "Task 2" }); _taskCollection.Add(new Task() { Id = 3, Title = "Task 3" }); } public IQueryable<Task> Tasks { get { return _taskCollection.AsQueryable(); } } } However, when I try to use this last one in my ViewModel constructor: public TaskListViewModel(ITasksModel tasksModel) { _tasksModel = tasksModel; _tasks = new DataServiceCollection<Task>(); _tasks.LoadAsync(_tasksModel.Tasks); } I get an exception: Only a typed DataServiceQuery object can be supplied when calling the LoadAsync method on DataServiceCollection. First of all, if this is the case, why not make the input parameter of LoadAsync be typed as DataServiceQuery? Second, what is the "proper" way of doing what I'm trying to accomplish?

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  • "cloud architecture" concepts in a system architecture diagrams

    - by markus
    If you design a distributed application for easy scale-out, or you just want to make use of any of the new “cloud computing” offerings by Amazon, Google or Microsoft, there are some typical concepts or components you usually end up using: distributed blob storage (aka S3) asynchronous, durable message queues (aka SQS) non-Relational-/non-transactional databases (like SimpleDB, Google BigTable, Azure SQL Services) distributed background worker pool load-balanced, edge-service processes handling user requests (often virtualized) distributed caches (like memcached) CDN (content delivery network like Akamai) Now when it comes to design and sketch an architecture that makes use of such patterns, are there any commonly used symbols I could use? Or even a download with some cool Visio stencils? :) It doesn’t have to be a formal system like UML but I think it would be great if there were symbols that everyone knows and understands, like we have commonly used shapes for databases or a documents, for example. I think it would be important to not mix it up with traditional concepts like a normal file system (local or network server/SAN), or a relational database. Simply speaking, I want to be able to draw some conclusions about an application’s scalability or data consistency issues by just looking at the system architecture overview diagram. Update: Thank you very much for your answers. I like the idea of putting a small "cloud symbol" on the traditional symbols. However I leave this thread open just in case someone will find specific symbols (maybe in a book or so) - or uploaded some pimped up Visio stencils ;)

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  • Thread-safe data structures

    - by Inso Reiges
    Hello, I have to design a data structure that is to be used in a multi-threaded environment. The basic API is simple: insert element, remove element, retrieve element, check that element exists. The structure's implementation uses implicit locking to guarantee the atomicity of a single API call. After i implemented this it became apparent, that what i really need is atomicity across several API calls. For example if a caller needs to check the existence of an element before trying to insert it he can't do that atomically even if each single API call is atomic: if(!data_structure.exists(element)) { data_structure.insert(element); } The example is somewhat awkward, but the basic point is that we can't trust the result of exists call anymore after we return from atomic context (the generated assembly clearly shows a minor chance of context switch between the two calls). What i currently have in mind to solve this is exposing the lock through the data structure's public API. This way clients will have to explicitly lock things, but at least they won't have to create their own locks. Is there a better commonly-known solution to these kinds of problems? And as long as we're at it, can you advise some good literature on thread-safe design? Thank you.

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  • WCF Manual SOAP POST using HttpWebRequest over https with Usertoken

    - by VonBlender
    Hi, I'm writing a client that calls a number of WCF webservices (written externallyt to my company) that are very similar in structure. The design I was hoping to use is to manually build the SOAP message from XML chunks that are stored in a database and then processed through a generic web service handler class. I have access to the WSDL's for each webservice and example working XML. The design approach is such that we can easily add to the message dynamically, hence the reason for not using the auto generated proxy classes I am basically at the last part now with the entire SOAP message constructed but am getting a SOAP fault security error returned. I have used fiddler to compare the message I'm sending with one that is sent using the normal (far simpler...) WCF generated proxy classes and can't see any difference apart from the id attribute of the Usertoken element in the SOAP header. This is where my lack of experience in this area isn't helping. I think this is because the id is generated automatically (presumably because we're using https). My question is how do I generate this programatically? I have searched for hours online but the majority of solutions are either using the proxy classes or not over https. I have briefly looked at WCE but aware this is replaced by WCF now so don't want to waste time looking into this if it's not the solution. Any help with this would be greatly appreciated. I can post some code examples when I'm back in work if it will help but the method I'm using is very straightforward and only using XElements and such like at the moment (as we're using linq to sql). thanks, Andy

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  • Exporting from SSRS 2008 ReportViewer to Excel Causes Duplicate Columns

    - by Daniel Coffman
    I have a report that groups months by quarters, so each quarter has three months and the display of the months under the quarter is toggled by the quarter header. It looks just fine in the ReportViewer, but when exporting to Excel the first month in the quarter with data is duplicated and appended to the end of the quarter group. Here is what it looks like in the ReportViewer (with Quarters 2 and 4 expanded, note May and June do not have any data and show blank columns by design): http://i.imgur.com/MykZE.png This is how it looks when exported to Excel: http://i.imgur.com/zfLuk.png The collapsed Quarter should only show the LAST month in the quarter. You can see that in the Excel export July is inserted in Q1 even though it should be hidden entirely since that quarter is collapsed, December is appended to Q2, January is inserted into Q3, and April is duplicated and appended to Q4. Exporting the any format OTHER than Excel works correctly and does not insert these columns. A similar bug for rows was filed and marked as "by design": http://connect.microsoft.com/SQLServer/feedback/details/508823/reporting-services-2008-group-by-export-to-excel-duplicate-rows-csv-ok-pdf-ok How do I stop the export to Excel feature from inserting these duplicate columns?

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  • Problem using Flash Components in multiple SWC files

    - by Ken Dunnington
    [Edit: Short version - how do you properly handle namespace collisions in SWC files if one SWC has fewer classes from that namespace than another?] I have a rather large Flash application which I'm building in Flash Builder (because coding/debugging in the Flash IDE is... not good) and I've got a ton of external SWC files which I'm linking in to my application. This has worked well so far - the file size is on the large side, but it's a lot simpler than loading in SWFs, especially since I am extending most of the classes in each SWC and adding custom code that way (it's a very design-heavy app.) The problem I'm having is when I have Flash Components, like ComboBox or TextInput, in more than one SWC. Whichever SWC was compiled last will work fine, but the others will fail with errors like the following: TypeError: Error #1034: Type Coercion failed: cannot convert flash.display::MovieClip@1f21adc1 to fl.controls.TextInput. at flash.display::Sprite/constructChildren() at flash.display::Sprite() at flash.display::MovieClip() at com.company.design.login::LoginForm() at com.company.view::Login()[/Users/ken/Workspace/src/com/company/view/Login.as:22] at com.company.view::Main/showLogin()[/Users/ken/Workspace/src/com/company/view/Main.as:209] at flash.events::EventDispatcher/dispatchEventFunction() at flash.events::EventDispatcher/dispatchEvent() at com.company.view::Navigation/handleUIClick()[/Users/ken/Workspace/src/com/company/view/Navigation.as:88] I've been researching components, ComponentShim, etc. but I'm running up against a brick wall. I thought it might be the fact that some of the components had their skins modified in the source FLA, so I tried replacing them with the default skins, but that didn't seem to help. How can I ensure that I have the components imported and available to all my classes, yet still be able to skin them and include them in my various FLAs? (I am never creating new instances of them, they are all laid out by my designer.)

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  • General Web Programming/designing Question: ?

    - by Prasad
    hi, I have been in web programming for 2 years (Self taught - a biology researcher by profession). I designed a small wiki with needed functionalities and a scientific RTE - ofcourse lot is expected. I used mootools framework and AJAX extensively. I was always curious when ever I saw the query strings passed from URL. Long encrypted query string directly getting passed to the server. Especially Google's design is such. I think this is the start of providing a Web Service to a client - I guess. Now, my question is : is this a special, highly professional, efficient / advanced web design technique to communicate queries via the URL ? I always felt that direct URL based communication is faster. I tried my bit and could send a query through the URL directly. here is the link: http://sgwiki.sdsc.edu/getSGMPage.php?8 By this , the client can directly link to the desired page instead of searching and / or can automate. There are many possibilities. The next request: Can I be pointed to such technique of web programming? oops: I am sorry, If I have not been able to convey my request clearly. Prasad.

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