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• How to store data on a machine whose power gets cut at random

  - by Sevas

  I have a virtual machine (Debian) running on a physical machine host. The virtual machine acts as a buffer for data that it frequently receives over the local network (the period for this data is 0.5s, so a fairly high throughput). Any data received is stored on the virtual machine and repeatedly forwarded to an external server over UDP. Once the external server acknowledges (over UDP) that it has received a data packet, the original data is deleted from the virtual machine and not sent to the external server again. The internet connection that connects the VM and the external server is unreliable, meaning it could be down for days at a time. The physical machine that hosts the VM gets its power cut several times per day at random. There is no way to tell when this is about to happen and it is not possible to add a UPS, a battery, or a similar solution to the system. Originally, the data was stored on a file-based HSQLDB database on the virtual machine. However, the frequent power cuts eventually cause the database script file to become corrupted (not at the file system level, i.e. it is readable, but HSQLDB can't make sense of it), which leads to my question: How should data be stored in an environment where power cuts can and do happen frequently? One option I can think of is using flat files, saving each packet of data as a file on the file system. This way if a file is corrupted due to loss of power, it can be ignored and the rest of the data remains intact. This poses a few issues however, mainly related to the amount of data likely being stored on the virtual machine. At 0.5s between each piece of data, 1,728,000 files will be generated in 10 days. This at least means using a file system with an increased number of inodes to store this data (the current file system setup ran out of inodes at ~250,000 messages and 30% disk space used). Also, it is hard (not impossible) to manage. Are there any other options? Are there database engines that run on Debian that would not get corrupted by power cuts? Also, what file system should be used for this? ext3 is what is used at the moment. The software that runs on the virtual machine is written using Java 6, so hopefully the solution would not be incompatible.

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• Concerning persistence size in the Linux Live Creator

  - by user63085

  Message : Hello everyone! I have ,for the last several months, used the Linux Live USB Creator which it is a very useful app to make portable OS on to flash drives. I mostly use this application to test and try out new OS's as they are released, before I decide to make a hard disk installatio on to the computer. In many cases, the application developers will allow the “persistence” feature in the flash-drive-installed OS, which is just another way of saying that after multiple boot-ups and shutdowns, all the changes made to the OS will be saved in the flash-drive. But I have a question about the limit of the Persistence size in Linux Live USB Creator (currently version 2.6). I install Super OS 10 on to a partition on my external drive which has 30 GB. I wanted to reserve 10 GB for the persistence so that I can install more applications and space will not run out as I update the installed applications or when I do system updates. But why is it that only 3950 MB can be put for persistence? It would be great if, when desired, as much more persistence space could be set aside so that the space will not run out soon. Also, as I have installed the OS on a 30 GB drive, I tried to see how much space is left. But it seems only the remaining of the Persistence space is displayed when I click on the File System folder. For example, after I have just installed it now, there is 3.5 GB of free space. Where can I access the remaining 26 GB or so drive space which is in the same drive? How do I access it Sir?? It would be helpful if any one could explain and help me with this. Most importantly, it would be a big relief if the persistence can be somehow expanded by a work-around so that I can continue using my SuperOS 10.04 (now heavily customized) OS, which unfortunately has just over 576 MB of space left now, after I removed OpenOffice.org and installed the Libre Office earlier today. This is what remains from the maximum allowable 3950 MB of space for persistence at set-up. Thanks in advance!

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• WCF REST on .Net 4.0

  - by AngelEyes

  A simple and straight forward article taken from: http://christopherdeweese.com/blog2/post/drop-the-soap-wcf-rest-and-pretty-uris-in-net-4 Drop the Soap: WCF, REST, and Pretty URIs in .NET 4 Years ago I was working in libraries when the Web 2.0 revolution began.  One of the things that caught my attention about early start-ups using the AJAX/REST/Web 2.0 model was how nice the URIs were for their applications.  Those were my first impressions of REST; pretty URIs.  Turns out there is a little more to it than that. REST is an architectural style that focuses on resources and structured ways to access those resources via the web.  REST evolved as an “anti-SOAP” movement, driven by developers who did not want to deal with all the complexity SOAP introduces (which is al lot when you don’t have frameworks hiding it all).  One of the biggest benefits to REST is that browsers can talk to rest services directly because REST works using URIs, QueryStrings, Cookies, SSL, and all those HTTP verbs that we don’t have to think about anymore. If you are familiar with ASP.NET MVC then you have been exposed to rest at some level.  MVC is relies heavily on routing to generate consistent and clean URIs.  REST for WCF gives you the same type of feel for your services.  Let’s dive in. WCF REST in .NET 3.5 SP1 and .NET 4 This post will cover WCF REST in .NET 4 which drew heavily from the REST Starter Kit and community feedback.  There is basic REST support in .NET 3.5 SP1 and you can also grab the REST Starter Kit to enable some of the features you’ll find in .NET 4. This post will cover REST in .NET 4 and Visual Studio 2010. Getting Started To get started we’ll create a basic WCF Rest Service Application using the new on-line templates option in VS 2010: When you first install a template you are prompted with this dialog: Dude Where’s my .Svc File? The WCF REST template shows us the new way we can simply build services.  Before we talk about what’s there, let’s look at what is not there: The .Svc File An Interface Contract Dozens of lines of configuration that you have to change to make your service work REST in .NET 4 is greatly simplified and leverages the Web Routing capabilities used in ASP.NET MVC and other parts of the web frameworks.  With REST in .NET 4 you use a global.asax to set the route to your service using the new ServiceRoute class.  From there, the WCF runtime handles dispatching service calls to the methods based on the Uri Templates. global.asax using System; using System.ServiceModel.Activation; using System.Web; using System.Web.Routing; namespace Blog.WcfRest.TimeService {     public class Global : HttpApplication     {         void Application_Start(object sender, EventArgs e)         {             RegisterRoutes();         }         private static void RegisterRoutes()         {             RouteTable.Routes.Add(new ServiceRoute("TimeService",                 new WebServiceHostFactory(), typeof(TimeService)));         }     } } The web.config contains some new structures to support a configuration free deployment.  Note that this is the default config generated with the template.  I did not make any changes to web.config. web.config <?xml version="1.0"?> <configuration>   <system.web>     <compilation debug="true" targetFramework="4.0" />   </system.web>   <system.webServer>     <modules runAllManagedModulesForAllRequests="true">       <add name="UrlRoutingModule" type="System.Web.Routing.UrlRoutingModule,            System.Web, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />     </modules>   </system.webServer>   <system.serviceModel>     <serviceHostingEnvironment aspNetCompatibilityEnabled="true"/>     <standardEndpoints>       <webHttpEndpoint>         <!--             Configure the WCF REST service base address via the global.asax.cs file and the default endpoint             via the attributes on the <standardEndpoint> element below         -->         <standardEndpoint name="" helpEnabled="true" automaticFormatSelectionEnabled="true"/>       </webHttpEndpoint>     </standardEndpoints>   </system.serviceModel> </configuration> Building the Time Service We’ll create a simple “TimeService” that will return the current time.  Let’s start with the following code: using System; using System.ServiceModel; using System.ServiceModel.Activation; using System.ServiceModel.Web; namespace Blog.WcfRest.TimeService {     [ServiceContract]     [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]     [ServiceBehavior(InstanceContextMode = InstanceContextMode.PerCall)]     public class TimeService     {         [WebGet(UriTemplate = "CurrentTime")]         public string CurrentTime()         {             return DateTime.Now.ToString();         }     } } The endpoint for this service will be http://[machinename]:[port]/TimeService.  To get the current time http://[machinename]:[port]/TimeService/CurrentTime will do the trick. The Results Are In Remember That Route In global.asax? Turns out it is pretty important.  When you set the route name, that defines the resource name starting after the host portion of the Uri. Help Pages in WCF 4 Another feature that came from the starter kit are the help pages.  To access the help pages simply append Help to the end of the service’s base Uri. Dropping the Soap Having dabbled with REST in the past and after using Soap for the last few years, the WCF 4 REST support is certainly refreshing.  I’m currently working on some REST implementations in .NET 3.5 and VS 2008 and am looking forward to working on REST in .NET 4 and VS 2010.

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• Review of Samsung Focus Windows Phone 7

  - by mbcrump

  I recently acquired a Samsung Focus Windows Phone 7 device from AT&T and wanted to share what I thought of it as an end-user. Before I get started, here are several of my write-ups for the Windows Phone 7. You may want to check out the second article titled: Hands-on WP7 Review of Prototype Hardware. From start to finish with the final version of Visual Studio Tools for Windows Phone 7 Hands-on : Windows Phone 7 Review on Prototype Hardware. Deploying your Windows Phone 7 Application to the actual hardware. Profile your Windows Phone 7 Application for Free Submitting a Windows Phone 7 Application to the Market. Samsung Focus i917 Phone Size: Perfect! I have been carrying around a Dell Streak (Android) and it is about half the size. It is really nice to have a phone that fits in your pocket without a lot of extra bulk. I bought a case for the Focus and it is still a perfect size.  The phone just feels right. Screen: It has a beautiful Super AMOLED 480x800 screen. I only wish it supported a higher resolution. The colors are beautiful especially in an Xbox Live Game.   3G: I use AT&T and I've had spotty reception. This really can't be blamed on the phone as much as the actual carrier. Battery: I've had excellent battery life compared to my iPhone and Android devices. I usually use my phone throughout the day on and off and still have a charge at the end of the day.  Camera/Video: I'm still looking for the option to send the video to YouTube or the Image to Twitter. The images look good, but the phone needs a forward facing camera. I like the iPhone/Android (Dell Streak) camera better. Built-in Speaker: Sounds great. It’s not a wimpy speaker that you cannot hear.  CPU: Very smooth transitioning from one screen to another. The prototype Windows Phone 7 that I had, was no where near as smooth. (It was also running a slower processor though). OS: I actually like the OS but a few things could be better. CONS: Copy and Paste (Supposed to come in the next update) We need more apps (Pandora missing was a big one for me and Slacker’s advertisement sucks!). As time passes, and more developers get on board then this will be fixed. The browser needs some major work. I have tried to make cross-platform (WP7, Android, iPhone and iPad) web apps and the browser that ships with WP7 just can’t handle it.  Apps need to be organized better. Instead of throw them all on one screen, it would help to allow the user to create categories. PROS: Hands down the best gaming experience on a phone. I have all three major phones (iphone, android and wp7). Nothing compares to the gaming experience on the WP7. The phone just works. I’ve had a LOT of glitches with my Android device. I’ve had maybe 2 with my WP7 device. Exchange and Office support are great. Nice integration with Twitter/Facebook and social media. Easy to navigate and find the information you need on one screen. Let’s look at a few pictures and we will wrap up with my final thoughts on the phone. WP7 Home Screen. Back of the phone is as stylish. It is hard to see due to the shadow but it is a very thin phone. What’s included? Manuals Ear buds Data Cable plus Power Adapter Phone Click a picture to enlarge So, what are my final thoughts on the Phone/OS? I love the Samsung Focus and would recommend it to anyone looking for a WP7 device. Like any first generation product, you need to give it a little while to mature. Right now the phone is missing several features that we are all used to using. That doesn’t mean a year from now it will be in the same situation. (I sure hope we won’t). If you are looking to get into mobile development, I believe WP7 is the easiest platform to develop from. This is especially true if you have a background in Silverlight or WPF.    Subscribe to my feed

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• 7 Reasons for Abandonment in eCommerce and the need for Contextual Support by JP Saunders

  - by Tuula Fai

  Shopper confidence, or more accurately the lack thereof, is the bane of the online retailer. There are a number of questions that influence whether a shopper completes a transaction, and all of those attributes revolve around knowledge. What products are available? What products are on offer? What would be the cost of the transaction? What are my options for delivery? In general, most online businesses do a good job of answering basic questions around the products as the shopper engages in the online journey, navigating the product catalog and working through the checkout process. The needs that are harder to address for the shopper are those that are less concerned with product specifics and more concerned with deciding whether the transaction met their needs and delivered value. A recent study by the Baymard Institute [1] finds that more than 60% of ecommerce site visitors will abandon their shopping cart. The study also identifies seven reasons for abandonment out of the commerce process [2]. Most of those reasons come down to poor usability within the commerce experience. Distractions. External distractions within the shopper’s external environment (TV, Children, Pets, etc.) or distractions on the eCommerce page can drive shopper abandonment. Ideally, the selection and check-out process should be straightforward. One common distraction is to drive the shopper away from the task at hand through pop-ups or re-directs. The shopper engaging with support information in the checkout process should not be directed away from the page to consume support. Though confidence may improve, the distraction also means abandonment may increase. Poor Usability. When the experience gets more complicated, buyer’s remorse can set in. While knowledge drives confidence, a lack of understanding erodes it. Therefore it is important that the commerce process is streamlined. In some cases, the number of clicks to complete a purchase is lengthy and unavoidable. In these situations, it is vital to ensure that the complexity of your experience can be explained with contextual support to avoid abandonment. If you can illustrate the solution to a complex action while the user is engaged in that action and address customer frustrations with your checkout process before they arise, you can decrease abandonment. Fraud. The perception of potential fraud can be enough to deter a buyer. Does your site look credible? Can shoppers trust your brand? Providing answers on the security of your experience and the levels of protection applied to profile information may play as big a role in ensuring the sale, as does the support you provide on the product offerings and purchasing process. Does it fit? If it is a clothing item or oversized furniture item, another common form of abandonment is for the shopper to question whether the item can be worn by the intended user. Providing information on the sizing applied to clothing, physical dimensions, and limitations on delivery/returns of oversized items will also assist the sale. A photo alone of the item will help, as it answers some of those questions, but won’t assuage all customer concerns about sizing and fit. Sometimes the customer doesn’t want to buy. Prospective buyers might be browsing through your catalog to kill time, or just might not have the money to purchase the item! You are unlikely to provide any information in contextual support to increase the likelihood to buy if the shopper already has no intentions of doing so. The customer will still likely abandon. Ensuring that any questions are proactively answered as they browse through your site can only increase their likelihood to return and buy at a future date. Can’t Buy. Errors or complexity at checkout can be another major cause of abandonment. Good contextual support is unlikely to help with severe errors caused by technical issues on your site, but it will have a big impact on customers struggling with complexity in the checkout process and needing a question answered prior to completing the sale. Embedded support within the checkout process to patiently explain how to complete a task will help increase conversion rates. Additional Costs. Tax, shipping and other costs or duties can dramatically increase the cost of the purchase and when unexpected, can increase abandonment, particularly if they can’t be adequately explained. Again, a lack of knowledge erodes confidence in the purchase, and cost concerns in particular, erode the perception of your brand’s trustworthiness. Again, providing information on what costs are additive and why they are being levied can decrease the likelihood that the customer will abandon out of the experience. Knowledge drives confidence and confidence drives conversion. If you’d like to understand best practices in providing contextual customer support in eCommerce to provide your shoppers with confidence, download the Oracle Cloud Service and Oracle Commerce - Contextual Support in Commerce White Paper. This white paper discusses the process of adding customer support, including a suggested process for finding where knowledge has the most influence on your shoppers and practical step-by-step illustrations on how contextual self-service can be added to your online commerce experience. Resources: [1] http://baymard.com/checkout-usability [2] http://baymard.com/blog/cart-abandonment

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• Silverlight Cream Monday WP7 App Review # 2

  - by Dave Campbell

  Today's Review (alphabetic order): GooNews, Grocery Shopping List, Need for Speed, SurfCube, and United Nations News. I'm a day late if these are going to be 'Monday' posts, but there are lots of apps, lots of goodness, and lots of email, so I might try to do 2 a week, we'll see. So once again I've got a small review of 5 apps that are either on my phone or have been. Disclaimers at the end. In this Issue:   GooNews is a very cool app from Shawn Wildermuth (AgiliTrain). I don't know if he uses this as a demo during his instruction, but it definitely serves a purpose... wanna pick up the top news items from Google on a never-ending basis? ... this is it. You can add your own keyword searches, and send stories to InstaPaper or share via email. I like this because it brings me the news quickly and updated, and works great. GooNews is by AgiliTrain and is Free This was a request by the author, and actually surprised me. I'm a big one for lists, but I would have just done a OneNote list to SkyDrive and to my phone. This app is a lot more than that, but will take you some setup to make it be 'yours'. For obvious reasons, there are no unit prices on things, so you have to set that up to get some idea of the cost of what you're shopping for. But if you do that, you'll get a nice total. Lots of thought went into the various categories and you can add your own. There's a bit of animation on the category selection that's nice. He seems to have covered all the bases necessary to use this, even shopping 'plans' that can be saved, and emailing of lists. As I said, I'm more of a raw list person, but if you take the time to set this up, it should work very nicely for you. Grocery Shopping List is by Grocery Shopper and is $0.99 ($1.99 after Feb 1) with a free trial. This was my 2nd commercial game I bought, and the one I've played the most. I ran the trial, thought it worked great, and bought it. I've had a lot of fun with this... there's no gas pedal.. your foot is in the carbeurator from the GO!, and unless you wanna tap the screen and brake like a little girl, just hang onto the steering wheel (the phone), and guide your way through. Hours of fun and challenges here. I like this because it's got some challenge to it, and the cars seem to be very realistic in their reactions. Need for Speed Undercover is by Electronic Arts is $4.99 and has a free trial. SurfCube Browser is another app by the folks that did the GuitarTuner I reviewed on Monday. You have to see SurfCube to believe it. You've probably seen the YouTube video, if not check SilverlightCream number 1017. The app works very solid, and just as the video demonstrates. I downloaded and tried this, and it immediately did 2 things: bought it, and pinned it to my start page. I like this because it's fun to work with, and it works great as a browser. I'm about *this* close to replacing the IE tile on my front page with SurfCube. SurfCube Browser is by Kinabalu Innovation Limited and is $1.99 and has a free trial. Coming in with another News app is United Nations News by Justin Angel. This is definitely a news aggregator for 'grown ups'... news, photos, videos, and radio broadcsts from the international community all in one very slick app. This is an amazingly well thought-out and complete app. Even better yet, Justin has the code on CodePlex. A very well-done International news aggregator. United Nations News is by Justin Angel and is Free. A few disclaimers: Feel free to write me about your app and tell me about it. While it would be very cool to receive a whole bunch of xap files to review, at this point, for technical reasons, I'm unable to side-load my device. Since I plan on only doing this one day a week (twice if I find time), and only 5, I may never get caught up, so if you send me some info, be patient. Re: games ... remember I'm old... I'm from the era of Colossal Cave and Zork. Duke-Nukem 2D and Captain Comic were awesome. I don't own an XBOX or any other game system, so take game reviews from my perspective -- who knows, it may be refreshing :) I won't pay for an app or game just to try it. If you expect me to test-drive your app, it's going to have to have a Free Trial. I'm still playing with the format, comments are welcome. I decided I should alphabetize the list today... so there's no order implied Let me know what you think of the idea of doing reviews, or the layout/whatever, and Stay in the 'Light! Twitter SilverlightNews | Twitter WynApse | WynApse.com | Tagged Posts | SilverlightCream Join me @ SilverlightCream | Phoenix Silverlight User Group Technorati Tags: Silverlight    Silverlight 3    Silverlight 4    Windows Phone MIX10

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• The Linux powered LAN Gaming House

  - by sachinghalot

  LAN parties offer the enjoyment of head to head gaming in a real-life social environment. In general, they are experiencing decline thanks to the convenience of Internet gaming, but Kenton Varda is a man who takes his LAN gaming very seriously. His LAN gaming house is a fascinating project, and best of all, Linux plays a part in making it all work.Varda has done his own write ups (short, long), so I'm only going to give an overview here. The setup is a large house with 12 gaming stations and a single server computer.The client computers themselves are rack mounted in a server room, and they are linked to the gaming stations on the floor above via extension cables (HDMI for video and audio and USB for mouse and keyboard). Each client computer, built into a 3U rack mount case, is a well specced gaming rig in its own right, sporting an Intel Core i5 processor, 4GB of RAM and an Nvidia GeForce 560 along with a 60GB SSD drive.Originally, the client computers ran Ubuntu Linux rather than Windows and the games executed under WINE, but Varda had to abandon this scheme. As he explains on his site:"Amazingly, a majority of games worked fine, although many had minor bugs (e.g. flickering mouse cursor, minor rendering artifacts, etc.). Some games, however, did not work, or had bad bugs that made them annoying to play."Subsequently, the gaming computers have been moved onto a more conventional gaming choice, Windows 7. It's a shame that WINE couldn't be made to work, but I can sympathize as it's rare to find modern games that work perfectly and at full native speed. Another problem with WINE is that it tends to suffer from regressions, which is hardly surprising when considering the difficulty of constantly improving the emulation of the Windows API. Varda points out that he preferred working with Linux clients as they were easier to modify and came with less licensing baggage.Linux still runs the server and all of the tools used are open source software. The hardware here is a Intel Xeon E3-1230 with 4GB of RAM. The storage hanging off this machine is a bit more complex than the clients. In addition to the 60GB SSD, it also has 2x1TB drives and a 240GB SDD.When the clients were running Linux, they booted over PXE using a toolchain that will be familiar to anyone who has setup Linux network booting. DHCP pointed the clients to the server which then supplied PXELINUX using TFTP. When booted, file access was accomplished through network block device (NBD). This is a very easy to use system that allows you to serve the contents of a file as a block device over the network. The client computer runs a user mode device driver and the device can be mounted within the file system using the mount command.One snag with offering file access via NBD is that it's difficult to impose any security restrictions on different areas of the file system as the server only sees a single file. The advantage is perfomance as the client operating system simply sees a block device, and besides, these security issues aren't relevant in this setup.Unfortunately, Windows 7 can't use NBD, so, Varda had to switch to iSCSI (which works in both server and client mode under Linux). His network cards are not compliant with this standard when doing a netboot, but fortunately, gPXE came to the rescue, and he boostraps it over PXE. gPXE is also available as an ISO image and is worth knowing about if you encounter an awkward machine that can't manage a network boot. It can also optionally boot from a HTTP server rather than the more traditional TFTP server.According to Varda, booting all 12 machines over the Gigabit Ethernet network is surprisingly fast, and once booted, the machines don't seem noticeably slower than if they were using local storage. Once loaded, most games attempt to load in as much data as possible, filling the RAM, and the the disk and network bandwidth required is small. It's worth noting that these are aspects of this project that might differ from some other thin client scenarios.At time of writing, it doesn't seem as though the local storage of the client machines is being utilized. Instead, the clients boot into Windows from an image on the server that contains the operating system and the games themselves. It uses the copy on write feature of LVM so that any writes from a client are added to a differencing image allocated to that client. As the administrator, Varda can log into the Linux server and authorize changes to the master image for updates etc.SummaryOverall, Varda estimates the total cost of the project at about $40,000, and of course, he needed a property that offered a large physical space in order to house the computers and the gaming workstations. Obviously, this project has stark differences to most thin client projects. The balance between storage, network usage, GPU power and security would not be typical of an office installation, for example. The only letdown is that WINE proved to be insufficiently compatible to run a wide variety of modern games, but that is, perhaps, asking too much of it, and hats off to Varda for trying to make it work.

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• Best way to store a large amount of game objects and update the ones onscreen

  - by user3002473

  Good afternoon guys! I'm a young beginner game developer working on my first large scale game project and I've run into a situation where I'm not quite sure what the best solution may be (if there is a lone solution). The question may be vague (if anyone can think of a better title after having read the question, please edit it) or broad but I'm not quite sure what to do and I thought it would help just to discuss the problem with people more educated in the field. Before we get started, here are some of the questions I've looked at for help in the past: Best way to keep track of game objects Elegant way to simulate large amounts of entities within a game world What is the most efficient container to store dynamic game objects in? I've also read articles about different data structures commonly used in games to store game objects such as this one about slot maps, but none of them are really what I'm looking for. Also, if it helps at all I'm using Python 3 to design the game. It has to be Python 3, if I could I would use C++ or Unityscript or something else, but I'm restricted to having to use Python 3. My game will be a form of side scroller shooter game. In said game the player will traverse large rooms with large amounts of enemies and other game objects to update (think some of the larger areas in Cave Story or Iji). The player obviously can't see the entire room all at once, so there is a viewport that follows the player around and renders only a selection of the room and the game objects that it contains. This is not a foreign concept. The part that's getting me confused has to do with how certain game objects are updated. Some of them are to be updated constantly, regardless of whether or not they can be seen. Other objects however are only to be updated when they are onscreen (for example, an enemy would only be updated to react to the player when it is onscreen or when it is in a certain range of the screen). Another problem is that game objects have to be easily referable by other game objects; something that happens in the player's update() method may affect another object in the world. Collision detection in games is always a serious problem. I need a way of containing the game objects such that it minimizes the number of cases when testing for collisions against one another. The final problem is that of creating and destroying game objects. I think this problem is pretty self explanatory. To store the game objects then I've considered a number of different methods. The original method I had was to simply store all the objects in a hash table by an id. This method was simple, and decently fast as it allows all the objects to be looked up in O(1) complexity, and also allows them to be deleted fairly easily. Hash collisions would not be a major problem; I wasn't originally planning on using computer generated ids to store the game objects I was going to rely on them all using ids given to them by the game designer (such names would be strings like 'Player' or 'EnemyWeapon4'), and even if I did use computer generated ids, if I used a decent hashing algorithm then the chances of collisions would be around 1 in 4 billion. The problem with using a hash table however is that it is inefficient in checking to see what objects are in range of the viewport. Considering the fact that certain game objects move (as well as the viewport itself), the only solution I could think of in order to only update objects that are in the viewport would be to iterate through every object in the hash table and check if it is in the viewport or not, updating only the ones that are in the valid area. This would be incredibly slow in scenarios where the amount of game objects exceeds 500, or even 200. The second solution was to store everything in a 2-d list. The world is partitioned up into cells (a tilemap essentially), where each cell or tile is the same size and is square. Each cell would contain a list of the game objects that are currently occupying it (each game object would be inserted into a cell depending on the center of the object's collision mask). A 2-d list would allow me to take the top-left and bottom-right corners of the viewport and easily grab a rectangular area of the grid containing only the cells containing entities that are in valid range to be updated. This method also solves the problem of collision detection; when I take an entity I can find the cell that it is currently in, then check only against entities in it's cell and the 8 cells around it. One problem with this system however is that it prohibits easy lookup of game objects. One solution I had would be to simultaneously keep a hash table that would contain all the positions of the objects in the 2-d list indexed by the id of said object. The major problem with a 2-d list is that it would need to be rebuilt every single game frame (along with the hash table of object positions), which may be a serious detriment to game speed. Both systems have ups and downs and seem to solve some of each other's problems, however using them both together doesn't seem like the best solution either. If anyone has any thoughts, ideas, suggestions, comments, opinions or solutions on new data structures or better implementations of the existing data structures I have in mind, please post, any and all criticism and help is welcome. Thanks in advance! EDIT: Please don't close the question because it has a bad title, I'm just bad with names!

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• Thread.Interrupt Is Evil

  - by Alois Kraus

  Recently I have found an interesting issue with Thread.Interrupt during application shutdown. Some application was crashing once a week and we had not really a clue what was the issue. Since it happened not very often it was left as is until we have got some memory dumps during the crash. A memory dump usually means WindDbg which I really like to use (I know I am one of the very few fans of it).  After a quick analysis I did find that the main thread already had exited and the thread with the crash was stuck in a Monitor.Wait. Strange Indeed. Running the application a few thousand times under the debugger would potentially not have shown me what the reason was so I decided to what I call constructive debugging. I did create a simple Console application project and try to simulate the exact circumstances when the crash did happen from the information I have via memory dump and source code reading. The thread that was  crashing was actually MS code from an old version of the Microsoft Caching Application Block. From reading the code I could conclude that the main thread did call the Dispose method on the CacheManger class which did call Thread.Interrupt on the cache scavenger thread which was just waiting for work to do. My first version of the repro looked like this   static void Main(string[] args) { Thread t = new Thread(ThreadFunc) { IsBackground = true, Name = "Test Thread" }; t.Start(); Console.WriteLine("Interrupt Thread"); t.Interrupt(); } static void ThreadFunc() { while (true) { object value = Dequeue(); // block until unblocked or awaken via ThreadInterruptedException } } static object WaitObject = new object(); static object Dequeue() { object lret = "got value"; try { lock (WaitObject) { } } catch (ThreadInterruptedException) { Console.WriteLine("Got ThreadInterruptException"); lret = null; } return lret; } I do start a background thread and call Thread.Interrupt on it and then directly let the application terminate. The thread in the meantime does plenty of Monitor.Enter/Leave calls to simulate work on it. This first version did not crash. So I need to dig deeper. From the memory dump I did know that the finalizer thread was doing just some critical finalizers which were closing file handles. Ok lets add some long running finalizers to the sample. class FinalizableObject : CriticalFinalizerObject { ~FinalizableObject() { Console.WriteLine("Hi we are waiting to finalize now and block the finalizer thread for 5s."); Thread.Sleep(5000); } } class Program { static void Main(string[] args) { FinalizableObject fin = new FinalizableObject(); Thread t = new Thread(ThreadFunc) { IsBackground = true, Name = "Test Thread" }; t.Start(); Console.WriteLine("Interrupt Thread"); t.Interrupt(); GC.KeepAlive(fin); // prevent finalizing it too early // After leaving main the other thread is woken up via Thread.Abort // while we are finalizing. This causes a stackoverflow in the CLR ThreadAbortException handling at this time. } With this changed Main method and a blocking critical finalizer I did get my crash just like the real application. The funny thing is that this is actually a CLR bug. When the main method is left the CLR does suspend all threads except the finalizer thread and declares all objects as garbage. After the normal finalizers were called the critical finalizers are executed to e.g. free OS handles (usually). Remember that I did call Thread.Interrupt as one of the last methods in the Main method. The Interrupt method is actually asynchronous and does wake a thread up and throws a ThreadInterruptedException only once unlike Thread.Abort which does rethrow the exception when an exception handling clause is left. It seems that the CLR does not expect that a frozen thread does wake up again while the critical finalizers are executed. While trying to raise a ThreadInterrupedException the CLR goes down with an stack overflow. Ups not so nice. Why has this nobody noticed for years is my next question. As it turned out this error does only happen on the CLR for .NET 4.0 (x86 and x64). It does not show up in earlier or later versions of the CLR. I have reported this issue on connect here but so far it was not confirmed as a CLR bug. But I would be surprised if my console application was to blame for a stack overflow in my test thread in a Monitor.Wait call. What is the moral of this story? Thread.Abort is evil but Thread.Interrupt is too. It is so evil that even the CLR of .NET 4.0 contains a race condition during the CLR shutdown. When the CLR gurus can get it wrong the chances are high that you get it wrong too when you use this constructs. If you do not believe me see what Patrick Smacchia does blog about Thread.Abort and List.Sort. Not only the CLR creators can get it wrong. The BCL writers do sometimes have a hard time with correct exception handling as well. If you do tell me that you use Thread.Abort frequently and never had problems with it I do suspect that you do not have looked deep enough into your application to find such sporadic errors.

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• NDepend Evaluation: Part 3

  - by Anthony Trudeau

  NDepend is a Visual Studio add-in designed for intense code analysis with the goal of high code quality. NDepend uses a number of metrics and aggregates the data in pleasing static and active visual reports. My evaluation of NDepend will be broken up into several different parts. In the first part of the evaluation I looked at installing the add-in.  And in the last part I went over my first impressions including an overview of the features.  In this installment I provide a little more detail on a few of the features that I really like. Dependency Matrix The dependency matrix is one of the rich visual components provided with NDepend.  At a glance it lets you know where you have coupling problems including cycles.  It does this with number indicating the weight of the dependency and a color-coding that indicates the nature of the dependency. Green and blue cells are direct dependencies (with the difference being whether the relationship is from row-to-column or column-to-row).  Black cells are the ones that you really want to know about.  These indicate that you have a cycle.  That is, type A refers to type B and type B also refers to Type A. But, that’s not the end of the story.  A handy pop-up appears when you hover over the cell in question.  It explains the color, the dependency, and provides several interesting links that will teach you more than you want to know about the dependency. You can double-click the problem cells to explode the dependency.  That will show the dependencies on a method-by-method basis allowing you to more easily target and fix the problem.  When you’re done you can click the back button on the toolbar. Dependency Graph The dependency graph is another component provided.  It’s complementary to the dependency matrix, but it isn’t as easy to identify dependency issues using the window. On a positive note, it does provide more information than the matrix. My biggest issue with the dependency graph is determining what is shown.  This was not readily obvious.  I ended up using the navigation buttons to get an acceptable view.  I would have liked to choose what I see. Once you see the types you want you can get a decent idea of coupling strength based on the width of the dependency lines.  Double-arrowed lines are problematic and are shown in red.  The size of the boxes will be related to the metric being displayed.  This is controlled using the Box Size drop-down in the toolbar.  Personally, I don’t find the size of the box to be helpful, so I change it to Constant Font. One nice thing about the display is that you can see the entire path of dependencies when you hover over a type.  This is done by color-coding the dependencies and dependants.  It would be nice if selecting the box for the type would lock the highlighting in place. I did find a perhaps unintended work-around to the color-coding.  You can lock the color-coding in by hovering over the type, right-clicking, and then clicking on the canvas area to clear the pop-up menu.  You can then do whatever with it including saving it to an image file with the color-coding. CQL NDepend uses a code query language (CQL) to work with your code just like it was a database.  CQL cannot be confused with the robustness of T-SQL or even LINQ, but it represents an impressive attempt at providing an expressive way to enumerate and interrogate your code. There are two main windows you’ll use when working with CQL.  The CQL Query Explorer allows you to define what queries (rules) are run as part of a report – I immediately unselected rules that I don’t want in my results.  The CQL Query Edit window is where you can view or author your own rules.  The explorer window is pretty self-explanatory, so I won’t mention it further other than to say that any queries you author will appear in the custom group. Authoring your own queries is really hard to screw-up.  The Intellisense-like pop-ups tell you what you can do while making composition easy.  I was able to create a query within two minutes of playing with the editor.  My query warns if any types that are interfaces don’t start with an “I”. WARN IF Count > 0 IN SELECT TYPES WHERE IsInterface AND !NameLike “I” The results from the CQL Query Edit window are immediate. That fact makes it useful for ad hoc querying.  It’s worth mentioning two things that could make the experience smoother.  First, out of habit from using Visual Studio I expect to be able to scroll and press Tab to select an item in the list (like Intellisense).  You have to press Enter when you scroll to the item you want.  Second, the commands are case-sensitive.  I don’t see a really good reason to enforce that. CQL has a lot of potential not just in enforcing code quality, but also enforcing architectural constraints that your enterprise has defined. Up Next My next update will be the final part of the evaluation.  I will summarize my experience and provide my conclusions on the NDepend add-in. ** View Part 1 of the Evaluation ** ** View Part 2 of the Evaluation ** Disclaimer: Patrick Smacchia contacted me about reviewing NDepend. I received a free license in return for sharing my experiences and talking about the capabilities of the add-in on this site. There is no expectation of a positive review elicited from the author of NDepend.

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• Cloud to On-Premise Connectivity Patterns

  - by Rajesh Raheja

  Do you have a requirement to convert an Opportunity in Salesforce.com to an Order/Quote in Oracle E-Business Suite? Or maybe you want the creation of an Oracle RightNow Incident to trigger an on-premise Oracle E-Business Suite Service Request creation for RMA and Field Scheduling? If so, read on. In a previous blog post, I discussed integrating TO cloud applications, however the use cases above are the reverse i.e. receiving data FROM cloud applications (SaaS) TO on-premise applications/databases that sit behind a firewall. Oracle SOA Suite is assumed to be on-premise with with Oracle Service Bus as the mediation and virtualization layer. The main considerations for the patterns are are security i.e. shielding enterprise resources; and scalability i.e. minimizing firewall latency. Let me use an analogy to help visualize the patterns: the on-premise system is your home - with your most valuable possessions - and the SaaS app is your favorite on-line store which regularly ships (inbound calls) various types of parcels/items (message types/service operations). You need the items at home (on-premise) but want to safe guard against misguided elements of society (internet threats) who may masquerade as postal workers and vandalize property (denial of service?). Let's look at the patterns. Pattern: Pull from Cloud The on-premise system polls from the SaaS apps and picks up the message instead of having it delivered. This may be done using Oracle RightNow Object Query Language or SOAP APIs. This is particularly suited for certain integration approaches wherein messages are trickling in, can be centralized and batched e.g. retrieving event notifications on an hourly schedule from the Oracle Messaging Service. To compare this pattern with the home analogy, you are avoiding any deliveries to your home and instead go to the post office/UPS/Fedex store to pick up your parcel. Every time. Pros: On-premise assets not exposed to the Internet, firewall issues avoided by only initiating outbound connections Cons: Polling mechanisms may affect performance, may not satisfy near real-time requirements Pattern: Open Firewall Ports The on-premise system exposes the web services that needs to be invoked by the cloud application. This requires opening up firewall ports, routing calls to the appropriate internal services behind the firewall. Fusion Applications uses this pattern, and auto-provisions the services on the various virtual hosts to secure the topology. This works well for service integration, but may not suffice for large volume data integration. Using the home analogy, you have now decided to receive parcels instead of going to the post office every time. A door mail slot cut out allows the postman can drop small parcels, but there is still concern about cutting new holes for larger packages. Pros: optimal pattern for near real-time needs, simpler administration once the service is provisioned Cons: Needs firewall ports to be opened up for new services, may not suffice for batch integration requiring direct database access Pattern: Virtual Private Networking The on-premise network is "extended" to the cloud (or an intermediary on-demand / managed service offering) using Virtual Private Networking (VPN) so that messages are delivered to the on-premise system in a trusted channel. Using the home analogy, you entrust a set of keys with a neighbor or property manager who receives the packages, and then drops it inside your home. Pros: Individual firewall ports don't need to be opened, more suited for high scalability needs, can support large volume data integration, easier management of one connection vs a multitude of open ports Cons: VPN setup, specific hardware support, requires cloud provider to support virtual private computing Pattern: Reverse Proxy / API Gateway The on-premise system uses a reverse proxy "API gateway" software on the DMZ to receive messages. The reverse proxy can be implemented using various mechanisms e.g. Oracle API Gateway provides firewall and proxy services along with comprehensive security, auditing, throttling benefits. If a firewall already exists, then Oracle Service Bus or Oracle HTTP Server virtual hosts can provide reverse proxy implementations on the DMZ. Custom built implementations are also possible if specific functionality (such as message store-n-forward) is needed. In the home analogy, this pattern sits in between cutting mail slots and handing over keys. Instead, you install (and maintain) a mailbox in your home premises outside your door. The post office delivers the parcels in your mailbox, from where you can securely retrieve it. Pros: Very secure, very flexible Cons: Introduces a new software component, needs DMZ deployment and management Pattern: On-Premise Agent (Tunneling) A light weight "agent" software sits behind the firewall and initiates the communication with the cloud, thereby avoiding firewall issues. It then maintains a bi-directional connection either with pull or push based approaches using (or abusing, depending on your viewpoint) the HTTP protocol. Programming protocols such as Comet, WebSockets, HTTP CONNECT, HTTP SSH Tunneling etc. are possible implementation options. In the home analogy, a resident receives the parcel from the postal worker by opening the door, however you still take precautions with chain locks and package inspections. Pros: Light weight software, IT doesn't need to setup anything Cons: May bypass critical firewall checks e.g. virus scans, separate software download, proliferation of non-IT managed software Conclusion The patterns above are some of the most commonly encountered ones for cloud to on-premise integration. Selecting the right pattern for your project involves looking at your scalability needs, security restrictions, sync vs asynchronous implementation, near real-time vs batch expectations, cloud provider capabilities, budget, and more. In some cases, the basic "Pull from Cloud" may be acceptable, whereas in others, an extensive VPN topology may be well justified. For more details on the Oracle cloud integration strategy, download this white paper.

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• Cloud to On-Premise Connectivity Patterns

  - by Rajesh Raheja

  Do you have a requirement to convert an Opportunity in Salesforce.com to an Order/Quote in Oracle E-Business Suite? Or maybe you want the creation of an Oracle RightNow Incident to trigger an on-premise Oracle E-Business Suite Service Request creation for RMA and Field Scheduling? If so, read on. In a previous blog post, I discussed integrating TO cloud applications, however the use cases above are the reverse i.e. receiving data FROM cloud applications (SaaS) TO on-premise applications/databases that sit behind a firewall. Oracle SOA Suite is assumed to be on-premise with with Oracle Service Bus as the mediation and virtualization layer. The main considerations for the patterns are are security i.e. shielding enterprise resources; and scalability i.e. minimizing firewall latency. Let me use an analogy to help visualize the patterns: the on-premise system is your home - with your most valuable possessions - and the SaaS app is your favorite on-line store which regularly ships (inbound calls) various types of parcels/items (message types/service operations). You need the items at home (on-premise) but want to safe guard against misguided elements of society (internet threats) who may masquerade as postal workers and vandalize property (denial of service?). Let's look at the patterns. Pattern: Pull from Cloud The on-premise system polls from the SaaS apps and picks up the message instead of having it delivered. This may be done using Oracle RightNow Object Query Language or SOAP APIs. This is particularly suited for certain integration approaches wherein messages are trickling in, can be centralized and batched e.g. retrieving event notifications on an hourly schedule from the Oracle Messaging Service. To compare this pattern with the home analogy, you are avoiding any deliveries to your home and instead go to the post office/UPS/Fedex store to pick up your parcel. Every time. Pros: On-premise assets not exposed to the Internet, firewall issues avoided by only initiating outbound connections Cons: Polling mechanisms may affect performance, may not satisfy near real-time requirements Pattern: Open Firewall Ports The on-premise system exposes the web services that needs to be invoked by the cloud application. This requires opening up firewall ports, routing calls to the appropriate internal services behind the firewall. Fusion Applications uses this pattern, and auto-provisions the services on the various virtual hosts to secure the topology. This works well for service integration, but may not suffice for large volume data integration. Using the home analogy, you have now decided to receive parcels instead of going to the post office every time. A door mail slot cut out allows the postman can drop small parcels, but there is still concern about cutting new holes for larger packages. Pros: optimal pattern for near real-time needs, simpler administration once the service is provisioned Cons: Needs firewall ports to be opened up for new services, may not suffice for batch integration requiring direct database access Pattern: Virtual Private Networking The on-premise network is "extended" to the cloud (or an intermediary on-demand / managed service offering) using Virtual Private Networking (VPN) so that messages are delivered to the on-premise system in a trusted channel. Using the home analogy, you entrust a set of keys with a neighbor or property manager who receives the packages, and then drops it inside your home. Pros: Individual firewall ports don't need to be opened, more suited for high scalability needs, can support large volume data integration, easier management of one connection vs a multitude of open ports Cons: VPN setup, specific hardware support, requires cloud provider to support virtual private computing Pattern: Reverse Proxy / API Gateway The on-premise system uses a reverse proxy "API gateway" software on the DMZ to receive messages. The reverse proxy can be implemented using various mechanisms e.g. Oracle API Gateway provides firewall and proxy services along with comprehensive security, auditing, throttling benefits. If a firewall already exists, then Oracle Service Bus or Oracle HTTP Server virtual hosts can provide reverse proxy implementations on the DMZ. Custom built implementations are also possible if specific functionality (such as message store-n-forward) is needed. In the home analogy, this pattern sits in between cutting mail slots and handing over keys. Instead, you install (and maintain) a mailbox in your home premises outside your door. The post office delivers the parcels in your mailbox, from where you can securely retrieve it. Pros: Very secure, very flexible Cons: Introduces a new software component, needs DMZ deployment and management Pattern: On-Premise Agent (Tunneling) A light weight "agent" software sits behind the firewall and initiates the communication with the cloud, thereby avoiding firewall issues. It then maintains a bi-directional connection either with pull or push based approaches using (or abusing, depending on your viewpoint) the HTTP protocol. Programming protocols such as Comet, WebSockets, HTTP CONNECT, HTTP SSH Tunneling etc. are possible implementation options. In the home analogy, a resident receives the parcel from the postal worker by opening the door, however you still take precautions with chain locks and package inspections. Pros: Light weight software, IT doesn't need to setup anything Cons: May bypass critical firewall checks e.g. virus scans, separate software download, proliferation of non-IT managed software Conclusion The patterns above are some of the most commonly encountered ones for cloud to on-premise integration. Selecting the right pattern for your project involves looking at your scalability needs, security restrictions, sync vs asynchronous implementation, near real-time vs batch expectations, cloud provider capabilities, budget, and more. In some cases, the basic "Pull from Cloud" may be acceptable, whereas in others, an extensive VPN topology may be well justified. For more details on the Oracle cloud integration strategy, download this white paper.

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• Google Checkout. Show shipping rates before logging in possible?

  - by Roeland

  I am trying to integrate google checkout with my current site. I am calculating the shipping on my end, before passing it to google checkout. The problem is, when a person click the "google checkout" button, it takes them to google checkout but it does not show the shipping. It actually states it will be calculated on next step. In the next step it actually shows a drop down with the ONE option for shipping that I passed, which is a flat rate.. The problem is, to get to the next step you have to enter a credit card. Also, my shop has the shipping shown in the cart, so it would seem confusing to go to checkout and have a price without shipping. Here is the test code I am using right now to see if I can get it to show shipping before logging in (sample it here: http://sensenich.bythepixel.com/test.html) <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html;charset=utf-8" /> <title>Site Title</title> </head> <body> <form method="POST" action="https://sandbox.google.com/checkout/api/checkout/v2/checkoutForm/Merchant/468503062558352" accept-charset="utf-8"> <input type="hidden" name="item_name_1" value="Peanut Butter"/> <input type="hidden" name="item_description_1" value="Chunky peanut butter."/> <input type="hidden" name="item_quantity_1" value="1"/> <input type="hidden" name="item_price_1" value="3.99"/> <input type="hidden" name="item_currency_1" value="USD"/> <input type="hidden" name="checkout-flow-support.merchant-checkout-flow-support.shipping-methods.flat-rate-shipping-1.name" value="UPS Next Day Air"/> <input type="hidden" name="checkout-flow-support.merchant-checkout-flow-support.shipping-methods.flat-rate-shipping-1.price" value="20.00"/> <input type="hidden" name="checkout-flow-support.merchant-checkout-flow-support.shipping-methods.flat-rate-shipping-1.price.currency" value="USD"/> <input type="hidden" name="_charset_" /> <!-- Button code --> <input type="image" name="Google Checkout" alt="Fast checkout through Google" src="http://sandbox.google.com/checkout/buttons/checkout.gif?merchant_id=468503062558352&w=180&h=46&style=white&variant=text&loc=en_US" height="46" width="180" /> </form> </body> </html>

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• WCF web service Data Members defaulting to null

  - by James

  I am new to WCF and created a simple REST service to accept an order object (series of strings from XML file), insert that data into a database, and then return an order object that contains the results. To test the service I created a small web project and send over a stream created from an xml doc. The problem is that even though all of the items in the xml doc get placed into the stream, the service is nullifying some of them when it receives the data. For example lineItemId will have a value but shipment status will show null. I step through the xml creation and verify that all the values are being sent. However, if I clear the datamembers and change the names around, it can work. Any help would be appreciated. This is the interface code [ServiceContract] public interface IShipping { [OperationContract] [WebInvoke(Method = "POST", UriTemplate = "/Orders/UpdateOrderStatus/", BodyStyle=WebMessageBodyStyle.Bare)] ReturnOrder UpdateOrderStatus(Order order); } [DataContract] public class Order { [DataMember] public string lineItemId { get; set; } [DataMember] public string shipmentStatus { get; set; } [DataMember] public string trackingNumber { get; set; } [DataMember] public string shipmentDate { get; set; } [DataMember] public string delvryMethod { get; set; } [DataMember] public string shipmentCarrier { get; set; } } [DataContract] public class ReturnOrder { [DataMember(Name = "Result")] public string Result { get; set; } } This is what I'm using to send over an Order object: string lineId = txtLineItem.Text.Trim(); string status = txtDeliveryStatus.Text.Trim(); string TrackingNumber = "1x22-z4r32"; string theMethod = "Ground"; string carrier = "UPS"; string ShipmentDate = "04/27/2010"; XNamespace nsOrders = "http://tempuri.org/order"; XElement myDoc = new XElement(nsOrders + "Order", new XElement(nsOrders + "lineItemId", lineId), new XElement(nsOrders + "shipmentStatus", status), new XElement(nsOrders + "trackingNumber", TrackingNumber), new XElement(nsOrders + "delvryMethod", theMethod), new XElement(nsOrders + "shipmentCarrier", carrier), new XElement(nsOrders + "shipmentDate", ShipmentDate) ); HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://localhost:3587/Deposco.svc/wms/Orders/UpdateOrderStatus/"); request.Method = "POST"; request.ContentType = "application/xml"; try { request.ContentLength = myDoc.ToString().Length; StreamWriter sw = new StreamWriter(request.GetRequestStream()); sw.Write(myDoc); sw.Close(); using (HttpWebResponse response = (HttpWebResponse)request.GetResponse()) { StreamReader reader = new StreamReader(response.GetResponseStream()); string responseString = reader.ReadToEnd(); XDocument.Parse(responseString).Save(@"c:\DeposcoSvcWCF.xml"); } } catch (WebException wEx) { Stream errorStream = ((HttpWebResponse)wEx.Response).GetResponseStream(); string errorMsg = new StreamReader(errorStream).ReadToEnd(); }

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• Generating custom-form documents from base-form plus XML?

  - by KlaymenDK

  Hi all, this is my first stack overflow, and it's a complex one. Sorry. My task is to generate custom documents from a basic template plus some XML without having a custom form design element for each case. Here's the whole picture: We are building a Lotus Notes (client, not web) application for world-wide application access control; the scope is something like 400.000 users being able to request access to any of 1000+ applications. Each application needs its own request form -- different number of approvers, various info required, that sort of thing. We simply can't have a thousand forms in a database (one per application), and anyway their maintenance really needs to be pushed from the developers to the application owners. So instead of custom forms, we'd like to create a generic "template" form that stores a block of basic fields, but then allows application owners to define another block of fields dynamically -- "I want a mandatory plain-text field named 'Name' here, and then a date field named 'Due' here that must be later than today's date, and then ...". I hope this makes sense (if not, think of it as a generic questionnaire application). I pretty much have the structure in place for designing the dynamic fields (form builder GUI - XML-encoded data - pre-rendered DXL for injecting into a form), including mark-up for field types, value options, and rudimentary field validation instructions. My problem is generating a document with this dynamic content injected at the proper location (without needing a custom form design element for each case). Doing the dynamic content via HTML is out. The Notes client web rendering is simply way too poor, and it would be quite a challenge to implement things like field validation instructions, date selectors, and name look-ups. DXL, on the other hand, would allow us to use native Notes fields and code. As a tech demo, I've managed to implement a custom form generator that injects the pre-rendered DXL for the dynamic content into a base form; but as I said, we don't want a ton of custom form design elements. I've tried to implement a way to create a document with the "store form in document" flag set, but once I've created the document from the base form, I can't get DXL access to the stored form design, and so I can't inject my dynamic content. I know this is not something Notes was ever intended to do. Has anyone ever tried something like it (and gotten away with it)? Thanks for reading this far. With a boatload of thanks in advance, Jan Gundtofte-Bruun

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• Linker Issues with boost::thread under linux using Eclipse and CMake

  - by OcularProgrammer

  I'm in the process of attempting to port some code across from PC to Ubuntu, and am having some issues due to limited experience developing under linux. We use CMake to generate all our build stuff. Under windows I'm making VS2010 projects, and under Linux I'm making Eclipse projects. I've managed to get my OpenCV stuff ported across successfully, but am having major headaches trying to port my threaded boost apps. Just so we're clear, the steps I have followed so-far on a clean Ubuntu 12 installation. (I've done 2 clean re-installs to try and fix potential library cock-ups, now I'm just giving up and asking): Install Eclipse and Eclipse CDT using my package manager Install CMake and CMake Gui using my package manager Install libboost-all-dev using my package manager So-far that's all I've done. I can create the eclipse project using CMake with no errors, so CMake is successfully finding my boost install. When I try and build through eclipse is when I get issues; The app I'm attempting to build uses boost::asio for some UDP I/O and boost::thread to create worker threads for the asio I/O services. I can successfully compile each module, but when I come to link I get spammed with errors such as: /usr/bin/c++ CMakeFiles/RE05DevelopmentDemo.dir/main.cpp.o CMakeFiles/RE05DevelopmentDemo.dir/RE05FusionListener/RE05FusionListener.cpp.o CMakeFiles/RE05DevelopmentDemo.dir/NewEye/NewEye.cpp.o -o RE05DevelopmentDemo -rdynamic -Wl,-Bstatic -lboost_system-mt -lboost_date_time-mt -lboost_regex-mt -lboost_thread-mt -Wl,-Bdynamic /usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libboost_thread-mt.a(thread.o): In function `void boost::call_once<void (*)()>(boost::once_flag&, void (*)()) [clone .constprop.98]': make[2]: Leaving directory `/home/david/Code/Build/Support/RE05DevDemo' (.text+0xc8): undefined reference to `pthread_key_create' /usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libboost_thread-mt.a(thread.o): In function `boost::this_thread::interruption_enabled()': (.text+0x540): undefined reference to `pthread_getspecific' make[1]: Leaving directory `/home/david/Code/Build/Support/RE05DevDemo' /usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libboost_thread-mt.a(thread.o): In function `boost::this_thread::disable_interruption::disable_interruption()': (.text+0x570): undefined reference to `pthread_getspecific' /usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libboost_thread-mt.a(thread.o): In function `boost::this_thread::disable_interruption::disable_interruption()': (.text+0x59f): undefined reference to `pthread_getspecific' Some Gotchas that I have collected from other StackOverflow posts and have already checked: The boost libs are all present at /usr/lib I am not getting any compile errors for inability to find the boost headers, so they must be getting found. I am trying to link statically, but I believe eclipse should be passing the correct arguments to make that happen since my CMakeLists.txt includes SET(Boost_USE_STATIC_LIBS ON) I'm officially out of ideas here, I have tried doing local builds of boost and a bunch of other stuff with no more success. I even re-installed Ubuntu to ensure I haven't completely fracked the libs directories and links with multiple weird versions or anything else. Any help would be muchly appreciated.

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• Are there any CMS editors out there which users can populate locked down HTML templates with content

  - by Deep

  Hi there, We work in email marketing, creating HTML/TEXT emails for clients. In essence we design HTML email templates for our clients. Clients then post us content (via a form) to populate these templates before we send them out. Right now we do this manually, basically cutting and pasting the content from their submitted form into the relevant parts of the template, which is time consuming and particularly mind-numbing. What we're looking for (and have so far been unable to find) is a simple system which will allow us to capture this client content in a sort of WYSIWYG HTML format. Basically they populate a locked down version of the template, entering text where necessary, before submitting to us. This is our most basic requirement, and a friend of mine kindly demo'd a proof of concept here: http://advantageone.co.uk/mbe/ Note: If you click on a text area in the body of the template, an editor pop ups. Now what we are looking for a CMS editor out there which can be easily adapted to do the above and the following for our end clients? User login View previously submitted campaigns that they have created and edit these Create new - selecting from template (assigned to their user/client id), perhaps being able to add new rows to the template. And have these HTML templates locked down so they can only edit what they're allowed too (like in the demo above), and perhaps make some areas required. Perhaps have a simple workflow or approval built in Allow us to lock submitted campaigns after a point so they can't be further edited, and as administrators view all campaigns from all users Be so incredibly simple, with any extraneous functionality switched off Essentially an extremley simple stripped down CMS, but we use the outputted HTML for sending out as an email, rather than publishing onto the web. Now to the actual dilemma: we're looking for something really simple, and the above sounds like a CMS. But we haven't been able to find anything that already does, or can be easily adapted to do this. Everything is either too complex, or simple and inflexible. We're sure there must be something off the shelf available, rather than us coding something ourselves. But we've kind of got stuck. Does anyone know of a system, or could recommend a system that can do the above out of the box, or with a few days tweaking? Forgive me if this is a little disjointed, if I'm being incredibly dopey and there is something out there please let me know! Kind regards, Dp.

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• Optimal template for change content via XMLHTTPRequest with JQuery,PHP,SQL [closed]

  - by B.F.

  This is my method to handle XMLHTTPRequests. Avoids mysql request, foreign access, nerves user, double requests. jquery var allow=true; var is_loaded=""; $(document).ready(function(){ .... $(".xx").on("click",functio(){ if(allow){ allow=false; if(is_loaded!="that"){ $.post("job.php", {job:"that",word:"aaa",number:"123"},function(data){ $(".aaa").html(data); is_loaded="that"; }); } setTimeout(function(){allow=true},500); } .... }); job.php <?PHP ob_start('ob_gzhandler'); if(!isset($_SERVER['HTTP_X_REQUESTED_WITH']) or strtolower($_SERVER['HTTP_X_REQUESTED_WITH']) != 'xmlhttprequest')exit("bad boy!"); if($_POST['job']=="that"){ include "includes/that.inc; } elseif($_POST['job']== .... ob_end_flush(); ?> that.inc if(!preg_match("/\w/",$_POST['word'])exit("bad boy!"); if(!is_numeric($_POST['number'])exit("bad boy!"); //exclude more. $path="temp/that_".$row['word']."txt"; if(file_exists($path) and filemtime("includes/that.inc")<$filemtime($path)){ readfile($path); } else{ include "includes/openSql.inc"; $call=sql_query("SELECT * FROM that WHERE name='".mysql_real_escape_string($_POST['word'])."'"); if(!$call)exit("ups"); $out=""; while($row=mysql_fetch_assoc($call)){ $out.=$_POST['word']." loves the color ".$row['color'].".<br/>"; } echo $out; $fn=fopen($path,"wb"); fputs($fn,$out); fclose($fn); } if something change at the database, you just have to delete involved files. Hope it was English.

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• Kernel Mode Rootkit

  - by Pajarito

  On the other 3 computers in my family, I believe that we have a kernel-mode rootkit for windows. It appears that the same rootkit is on all of them. We think. We changed all the important passwords from my computer, running linux right now. On all of the infected computers is Symantic Endpoint Protection, because it's free from the university where my mom and dad work. In my opinion symantec is a piece of crap, seeing as it didn't even manager to delete the tracking cookies it found when I tried it on my own computer. The Computers and their set-ups: Computer A: Vista Business; symantec antivirus. runs it as admin, no password. IE8. no other security software other than what comes with windows. IE8 security settings the default Computer B: XP Home Premium; symantec antivirus. runs as normal user, no password, admin account with weak password, spybot, uses IE8 with default settings, sometimes Firefox Computer C: XP Home Premium; symantec antivirus. runs as normal user, no password, admin account with weak password, uses IE8 with default settings, no other security programs except what came with windows This is what's happening. Cut and pasted from my dad's forum post. -- When I scanned my laptop (Dell XPS M1330 with Windows Vista Small Business), Symantec Endpoint Protection hangs for a while, perhaps 10 seconds or so, on some of the following files 9129837.exe, hide_evr2.sys, VirusRemoval.vbs, NewVirusRemoval.vbs, dll.dll, alsmt.ext, and _epnt.sys. It does this if a run a scan that I set up to run on a new thumbnail drive and it does this even if the thumbnail is not plugged in. It doesn't seem to do this if I scan only the C: drive. I've check for problems with symantec endpoint protection and also with Microsoft Security Essentials and Malwarebytes Anti-Malware. They found nothing and I can't find anything by searching for hidden files. Next I tried microsoft's rootkitrevealer. It (rootkitrevealer) finds 279660 (or so) discrepancies and the interface is so glitchy after that I can't really figure out what is going on. The screen is squirrely. The rootkitrevealer pulls up many files in the folder \programdata\applicationdata and there are numberous appended \applicationdata on the end of that as well. -- As you can see, what we did was install MSE and MBAM and scan with both of them. Nothing but a tracking cookie. Then I took over and ran rootkitrevealer.exe from MicroSoft from a flash drive. It found a bunch of discrepancies, but only about 20 or so where security related, the rest being files that you just couldn't see from Windows Explorer. I couldn't see whether of not the files list above, the ones that the scan was hanging on, where in the list. The other thing is, I have no idea what to do about the things the scan comes up with. Then we checked the other computers and they do the same thing when you scan with Symantec. The people at the university seen to think that dad might not have a virus, but 2 of the computers slowed down noticably AND IE8 started acting all funny. None of my family is very computer oriented, and 2 of the possible causes for the rootkit are: -My dad bought a new flash drive, which shipped with a data security executable on it -My dad has to download lots of articles for his work Those are the only things that stand out, but it could have been anything. We are currently backing up our data, and I'll post again after trying IceSword 1.22. I just looked at my dad's forum topic, and someone recommended GMER. I'll try that too.

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• apache+mod_wsgi configuration for django project(s) on a quad core

  - by Stefano

  I've been experiment quite some time with a "typical" django setting upon nginx+apache2+mod_wsgi+memcached(+postgresql) (reading the doc and some questions on SO and SF, see comments) Since I'm still unsatisfied with the behavior (definitely because of some bad misconfiguration on my part) I would like to know what a good configuration would look like with these hypotesis: Quad-Core Xeon 2.8GHz 8 gigs memory several django projects (anything special related to this?) These are excerpts form my current confs: apache2 SetEnv VHOST null #WSGIPythonOptimize 2 <VirtualHost *:8082> ServerName subdomain.domain.com ServerAlias www.domain.com SetEnv VHOST subdomain.domain AddDefaultCharset UTF-8 ServerSignature Off LogFormat "%{X-Real-IP}i %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-agent}i\"" custom ErrorLog /home/project1/var/logs/apache_error.log CustomLog /home/project1/var/logs/apache_access.log custom AllowEncodedSlashes On WSGIDaemonProcess subdomain.domain user=www-data group=www-data threads=25 WSGIScriptAlias / /home/project1/project/wsgi.py WSGIProcessGroup %{ENV:VHOST} </VirtualHost> wsgi.py import os import sys # setting all the right paths.... _realpath = os.path.realpath(os.path.dirname(__file__)) _public_html = os.path.normpath(os.path.join(_realpath, '../')) sys.path.append(_realpath) sys.path.append(os.path.normpath(os.path.join(_realpath, 'apps'))) sys.path.append(os.path.normpath(_public_html)) sys.path.append(os.path.normpath(os.path.join(_public_html, 'libs'))) sys.path.append(os.path.normpath(os.path.join(_public_html, 'django'))) os.environ['DJANGO_SETTINGS_MODULE'] = 'settings' import django.core.handlers.wsgi _application = django.core.handlers.wsgi.WSGIHandler() def application(environ, start_response): """ Launches django passing over some environment (domain name) settings """ application_group = environ['mod_wsgi.application_group'] """ wsgi application group is required. It's also used to generate the HOST.DOMAIN.TLD:PORT parameters to pass over """ assert application_group fields = application_group.replace('|', '').split(':') server_name = fields[0] os.environ['WSGI_APPLICATION_GROUP'] = application_group os.environ['WSGI_SERVER_NAME'] = server_name if len(fields) > 1 : os.environ['WSGI_PORT'] = fields[1] splitted = server_name.rsplit('.', 2) assert splitted >= 2 splited.reverse() if len(splitted) > 0 : os.environ['WSGI_TLD'] = splitted[0] if len(splitted) > 1 : os.environ['WSGI_DOMAIN'] = splitted[1] if len(splitted) > 2 : os.environ['WSGI_HOST'] = splitted[2] return _application(environ, start_response)` folder structure in case it matters (slightly shortened actually) /home/www-data/projectN/var/logs /project (contains manage.py, wsgi.py, settings.py) /project/apps (all the project ups are here) /django /libs Please forgive me in advance if I overlooked something obvious. My main question is about the apache2 wsgi settings. Are those fine? Is 25 threads an /ok/ number with a quad core for one only django project? Is it still ok with several django projects on different virtual hosts? Should I specify 'process'? Any other directive which I should add? Is there anything really bad in the wsgi.py file? I've been reading about potential issues with the standard wsgi.py file, should I switch to that? Or.. should this conf just be running fine, and I should look for issues somewhere else? So, what do I mean by "unsatisfied": well, I often get quite high CPU WAIT; but what is worse, is that relatively often apache2 gets stuck. It just does not answer anymore, and has to be restarted. I have setup a monit to take care of that, but it ain't a real solution. I have been wondering if it's an issue with the database access (postgresql) under heavy load, but even if it was, why would the apache2 processes get stuck? Beside these two issues, performance is overall great. I even tried New Relic and got very good average results.

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• shutdown.exe on Win Server2k3 64-bit cannot be found

  - by normalocity

  Server 2003 SP2 64-bit Verified my path settings are correct, as I can run other executables within the "system32" folder without issue. If I cd to "c:\windows\system32\" folder, and try to run "shutdown /?" I get "shutdown is not recognized as a valid..." you know - the message you get when you type a command that doesn't exist. Doing a "dir *.exe" inside the "system32" folder, also doesn't return "shutdown.exe" as one of the results. HOWEVER - if I go through Windows Explorer - there it is! I can see shutdown.exe. Also, if I go to "Start - Run" and type "shutdown /?", it works fine. So, works in the GUI, not on the command line. very strange. This is an excerpt of the last portion of "dir *.exe" when run on the "system32" folder. Note the lack of commonly used executables such as "shutdown.exe" and "tsadmin.exe" 02/18/2007 07:00 AM 24,064 route.exe 02/18/2007 07:00 AM 29,184 routemon.exe 02/18/2007 07:00 AM 14,848 rsh.exe 02/18/2007 07:00 AM 67,072 rsopprov.exe 02/18/2007 07:00 AM 77,824 rtcshare.exe 02/18/2007 07:00 AM 18,432 runas.exe 02/18/2007 07:00 AM 34,816 rundll32.exe 02/18/2007 07:00 AM 18,432 runonce.exe 02/18/2007 07:00 AM 13,312 savedump.exe 03/19/2009 07:51 PM 49,152 sc.exe 02/18/2007 07:00 AM 90,112 scardsvr.exe 02/18/2007 07:00 AM 152,064 schtasks.exe 02/18/2007 07:00 AM 16,384 schupgr.exe 02/18/2007 07:00 AM 31,232 sdbinst.exe 02/18/2007 07:00 AM 36,352 secedit.exe 02/18/2007 07:00 AM 32,768 sethc.exe 06/28/2006 12:12 AM 31,232 SetLACState.exe 02/18/2007 07:00 AM 41,472 setup.exe 02/18/2007 07:00 AM 25,088 setup16.exe 02/18/2007 07:00 AM 20,480 setupn.exe 02/18/2007 07:00 AM 60,416 setx.exe 02/18/2007 07:00 AM 10,752 sfc.exe 02/18/2007 07:00 AM 76,288 sfmprint.exe 02/18/2007 07:00 AM 11,776 sfmpsexe.exe 02/18/2007 07:00 AM 65,024 sfmsvc.exe 02/18/2007 07:00 AM 38,400 shmgrate.exe 02/18/2007 07:00 AM 71,168 sigverif.exe 02/18/2007 07:00 AM 26,112 skeys.exe 02/18/2007 07:00 AM 96,256 smlogsvc.exe 02/18/2007 07:00 AM 53,760 smss.exe 02/18/2007 07:00 AM 40,960 snmp.exe 02/18/2007 07:00 AM 25,088 sort.exe 02/18/2007 07:00 AM 9,728 sprestrt.exe 02/18/2007 07:00 AM 10,240 subst.exe 02/18/2007 07:00 AM 14,848 svchost.exe 02/18/2007 07:00 AM 54,272 syncapp.exe 02/18/2007 07:00 AM 18,896 sysedit.exe 02/18/2007 07:00 AM 29,696 syskey.exe 02/18/2007 07:00 AM 107,520 sysocmgr.exe 02/18/2007 07:00 AM 79,360 systeminfo.exe 02/18/2007 07:00 AM 3,072 systray.exe 02/18/2007 07:00 AM 58,880 takeown.exe 02/18/2007 07:00 AM 32,768 tapicfg.exe 02/18/2007 07:00 AM 84,480 taskkill.exe 02/18/2007 07:00 AM 87,552 tasklist.exe 02/18/2007 07:00 AM 168,960 taskmgr.exe 02/18/2007 07:00 AM 13,824 tcmsetup.exe 02/18/2007 07:00 AM 21,504 tcpsvcs.exe 02/18/2007 07:00 AM 28,672 timeout.exe 02/18/2007 07:00 AM 419,328 tracerpt.exe 02/18/2007 07:00 AM 12,800 tracert.exe 02/18/2007 07:00 AM 26,624 tsecimp.exe 02/18/2007 07:00 AM 37,376 typeperf.exe 10/24/2008 04:12 PM 64,000 tzchange.exe 02/18/2007 07:00 AM 5,632 unlodctr.exe 02/18/2007 07:00 AM 321,024 upg351db.exe 02/18/2007 07:00 AM 16,896 ups.exe 02/18/2007 07:00 AM 4,096 user.exe 02/18/2007 07:00 AM 26,112 userinit.exe 02/18/2007 07:00 AM 49,152 utilman.exe 02/18/2007 07:00 AM 47,104 uwdf.exe 02/18/2007 07:00 AM 29,184 verclsid.exe 02/18/2007 07:00 AM 112,640 verifier.exe 02/18/2007 07:00 AM 1,129 vwipxspx.exe 02/18/2007 07:00 AM 55,296 w32tm.exe 02/18/2007 07:00 AM 38,400 waitfor.exe 02/18/2007 07:00 AM 39,424 wdfmgr.exe 02/18/2007 07:00 AM 62,464 wextract.exe 02/18/2007 07:00 AM 38,400 where.exe 02/18/2007 07:00 AM 48,640 whoami.exe 02/18/2007 07:00 AM 36,864 winchat.exe 08/13/2007 06:45 PM 206,336 WinFXDocObj.exe 02/18/2007 07:00 AM 8,704 winhlp32.exe 02/18/2007 07:00 AM 12,800 winmsd.exe 02/18/2007 07:00 AM 2,112 winspool.exe 02/18/2007 07:00 AM 6,656 winver.exe 08/21/2002 05:13 AM 189,952 WISPTIS.EXE 02/18/2007 07:00 AM 67,072 wlbs.exe 02/18/2007 07:00 AM 10,560 wowexec.exe 02/18/2007 07:00 AM 10,752 wowreg32.exe 02/18/2007 07:00 AM 31,232 wpnpinst.exe 02/18/2007 07:00 AM 5,632 write.exe 02/18/2007 07:00 AM 114,688 wscript.exe 02/18/2007 07:00 AM 30,720 xcopy.exe

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• shutdown.exe on Win Server2k3 cannot be found

  - by normalocity

  Server 2003 SP2 64-bit Verified my path settings are correct, as I can run other executables within the "system32" folder without issue. If I cd to "c:\windows\system32\" folder, and try to run "shutdown /?" I get "shutdown is not recognized as a valid..." you know - the message you get when you type a command that doesn't exist. Doing a "dir *.exe" inside the "system32" folder, also doesn't return "shutdown.exe" as one of the results. HOWEVER - if I go through Windows Explorer - there it is! I can see shutdown.exe. Also, if I go to "Start - Run" and type "shutdown /?", it works fine. So, works in the GUI, not on the command line. very strange. This is an excerpt of the last portion of "dir *.exe" when run on the "system32" folder. Note the lack of commonly used executables such as "shutdown.exe" and "tsadmin.exe" 02/18/2007 07:00 AM 24,064 route.exe 02/18/2007 07:00 AM 29,184 routemon.exe 02/18/2007 07:00 AM 14,848 rsh.exe 02/18/2007 07:00 AM 67,072 rsopprov.exe 02/18/2007 07:00 AM 77,824 rtcshare.exe 02/18/2007 07:00 AM 18,432 runas.exe 02/18/2007 07:00 AM 34,816 rundll32.exe 02/18/2007 07:00 AM 18,432 runonce.exe 02/18/2007 07:00 AM 13,312 savedump.exe 03/19/2009 07:51 PM 49,152 sc.exe 02/18/2007 07:00 AM 90,112 scardsvr.exe 02/18/2007 07:00 AM 152,064 schtasks.exe 02/18/2007 07:00 AM 16,384 schupgr.exe 02/18/2007 07:00 AM 31,232 sdbinst.exe 02/18/2007 07:00 AM 36,352 secedit.exe 02/18/2007 07:00 AM 32,768 sethc.exe 06/28/2006 12:12 AM 31,232 SetLACState.exe 02/18/2007 07:00 AM 41,472 setup.exe 02/18/2007 07:00 AM 25,088 setup16.exe 02/18/2007 07:00 AM 20,480 setupn.exe 02/18/2007 07:00 AM 60,416 setx.exe 02/18/2007 07:00 AM 10,752 sfc.exe 02/18/2007 07:00 AM 76,288 sfmprint.exe 02/18/2007 07:00 AM 11,776 sfmpsexe.exe 02/18/2007 07:00 AM 65,024 sfmsvc.exe 02/18/2007 07:00 AM 38,400 shmgrate.exe 02/18/2007 07:00 AM 71,168 sigverif.exe 02/18/2007 07:00 AM 26,112 skeys.exe 02/18/2007 07:00 AM 96,256 smlogsvc.exe 02/18/2007 07:00 AM 53,760 smss.exe 02/18/2007 07:00 AM 40,960 snmp.exe 02/18/2007 07:00 AM 25,088 sort.exe 02/18/2007 07:00 AM 9,728 sprestrt.exe 02/18/2007 07:00 AM 10,240 subst.exe 02/18/2007 07:00 AM 14,848 svchost.exe 02/18/2007 07:00 AM 54,272 syncapp.exe 02/18/2007 07:00 AM 18,896 sysedit.exe 02/18/2007 07:00 AM 29,696 syskey.exe 02/18/2007 07:00 AM 107,520 sysocmgr.exe 02/18/2007 07:00 AM 79,360 systeminfo.exe 02/18/2007 07:00 AM 3,072 systray.exe 02/18/2007 07:00 AM 58,880 takeown.exe 02/18/2007 07:00 AM 32,768 tapicfg.exe 02/18/2007 07:00 AM 84,480 taskkill.exe 02/18/2007 07:00 AM 87,552 tasklist.exe 02/18/2007 07:00 AM 168,960 taskmgr.exe 02/18/2007 07:00 AM 13,824 tcmsetup.exe 02/18/2007 07:00 AM 21,504 tcpsvcs.exe 02/18/2007 07:00 AM 28,672 timeout.exe 02/18/2007 07:00 AM 419,328 tracerpt.exe 02/18/2007 07:00 AM 12,800 tracert.exe 02/18/2007 07:00 AM 26,624 tsecimp.exe 02/18/2007 07:00 AM 37,376 typeperf.exe 10/24/2008 04:12 PM 64,000 tzchange.exe 02/18/2007 07:00 AM 5,632 unlodctr.exe 02/18/2007 07:00 AM 321,024 upg351db.exe 02/18/2007 07:00 AM 16,896 ups.exe 02/18/2007 07:00 AM 4,096 user.exe 02/18/2007 07:00 AM 26,112 userinit.exe 02/18/2007 07:00 AM 49,152 utilman.exe 02/18/2007 07:00 AM 47,104 uwdf.exe 02/18/2007 07:00 AM 29,184 verclsid.exe 02/18/2007 07:00 AM 112,640 verifier.exe 02/18/2007 07:00 AM 1,129 vwipxspx.exe 02/18/2007 07:00 AM 55,296 w32tm.exe 02/18/2007 07:00 AM 38,400 waitfor.exe 02/18/2007 07:00 AM 39,424 wdfmgr.exe 02/18/2007 07:00 AM 62,464 wextract.exe 02/18/2007 07:00 AM 38,400 where.exe 02/18/2007 07:00 AM 48,640 whoami.exe 02/18/2007 07:00 AM 36,864 winchat.exe 08/13/2007 06:45 PM 206,336 WinFXDocObj.exe 02/18/2007 07:00 AM 8,704 winhlp32.exe 02/18/2007 07:00 AM 12,800 winmsd.exe 02/18/2007 07:00 AM 2,112 winspool.exe 02/18/2007 07:00 AM 6,656 winver.exe 08/21/2002 05:13 AM 189,952 WISPTIS.EXE 02/18/2007 07:00 AM 67,072 wlbs.exe 02/18/2007 07:00 AM 10,560 wowexec.exe 02/18/2007 07:00 AM 10,752 wowreg32.exe 02/18/2007 07:00 AM 31,232 wpnpinst.exe 02/18/2007 07:00 AM 5,632 write.exe 02/18/2007 07:00 AM 114,688 wscript.exe 02/18/2007 07:00 AM 30,720 xcopy.exe

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• Multiple data centers and HTTP traffic: DNS Round Robin is the ONLY way to assure instant fail-over?

  - by vmiazzo

  Hi, Multiple A records pointing to the same domain seem to be used almost exclusively to implement DNS Round Robin as a cheap load balancing technique. The usual warning against DNS RR is that it is not good for high availability. When 1 IP goes down clients will continue to use it for minutes. A load balancer is often suggested as a better choice. Both claims are not completely true: When the traffic is HTTP then, most of the HTML browsers are able to automatically try the next A record if the previous is down, without a new DNS look-up. Read here chapter 3.1 and here. When multiple data centers are involved then, DNS RR is the only option to distribute traffic across them. So, is it true that, with multiple data centers and HTTP traffic, the use of DNS RR is the ONLY way to assure instant fail-over when one data center goes down? Thanks, Valentino Edit: Off course each data center has a local Load Balancer with hot spare. It's OK to sacrifice session affinity for an instant fail-over. AFAIK the only way for a DNS to suggest a data center instead of another is to reply with just the IP (or IPs) associated to that data center. If the data center becomes unreachable then all those IP are also unreachables. This means that, even if smart HTML browsers are able to instantly try another A record , all the attempts will fail until the local cache entry expires and a new DNS lookup is done, fetching the new working IPs (I assume DNS automatically suggests to a new data center when one fail). So, "smart DNS" cannot assure instant fail-over. Conversely a DNS round-robin permits it. When one data center fail, the smart HTML browsers (most of them) instantly try the other cached A records jumping to another (working) data center. So, DNS round-robin doesn't assure session affinity or the lowest RTT but seems to be the only way to assure instant fail-over when the clients are "smart" HTML browsers. Edit 2: Some people suggest TCP Anycast as a definitive solution. In this paper (chapter 6) is explained that Anycast fail-over is related to BGP convergence. For this reason Anycast can employ from 15 minutes to 20 seconds to complete. 20 seconds are possible on networks where the topology was optimized for this. Probably just CDN operators can grant such fast fail-overs. Edit 3:* I did some DNS look-ups and traceroutes (maybe some expert can double check) and: The only CDN using TCP Anycast seems to be CacheFly, other operators like CDN networks and BitGravity use CacheFly. Seems that their edges cannot be used as reverse proxies. Therefore, they cannot be used to grant instant failover. Akamai and LimeLight seems to use geo-aware DNS. But! They return multiple A records. From traceroutes seems that the returned IPs are on the same data center. So, I'm puzzled on how they can offer a 100% SLA when one data center goes down.

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• IP Micro-outages, telephone micro-outages, and CATV micro-outages

  - by Michael Graff

  This is a long and complicated question, mostly because it has been going on for 2.5 years without a solution in sight. It also is only one-third computer related, the other two-thirds are cable TV and cable-phone related. Background I have COX Communications for a cable provider, and we get Internet, digital cable TV, and digital phone service through them. The Internet is a SB5101 right now, and has been a DPC2100 and SB5120 in the past. Same results. The phone service is provided through a telephone interface mounted on the outside of the house (not classic VoIP) and the CATV is through a Scientific Atlanta receiver without DVR. I do have a TiVo connected to the CATV box. Symptoms The CATV shows "blocking" -- sometimes very very short duration where a few blocks appear on the screen. Sometimes it lasts long enough that the video "pauses" for 2-5 seconds, and rarely but not unseen the audio also fails. The CATV decoder box shows no correctable (FEC) or uncorrectable errors. That is, all BER counters are zero for the video stream. The Internet shows "micro-outages" where it appears that sent packets are not making it out, but I continue to receive packets from local modems. That is, pings stop coming back, but I continue to see modems broadcast for DHCP, and sometimes they ask more than once. The cable modem shows no errors during this time, but cable modems lie like you would not believe. It is actually possible to unplug the coax from the modem for 20 seconds and it reports NO ERRORS to the provider's tools. The phone service cuts out for 1-3 seconds, infrequently. When this happens, I hear NOTHING (not even comfort noise) and the remote side hears a "click" as if I were getting a call waiting message. However, there is no call incoming, other than the one I'm currently on of course. Things SEEM to happen more frequently when the temperature outside swings from cold to warm, so fall/spring seems worse than summer/winter. All micro-outages occur between once or twice a day (which I could ignore) to 10 times per hour. All SNR, signal levels, noise levels, etc. show very close to optimal when measured. COX's diagnosis This is a continual pain for me. Over the last 2.5 years, they have opened, "fixed" something, and closed the tickets. They close it without confirming that it is indeed better, and when I reopen they cannot do that, but instead they open a new ticket and send yet another low-level tech out to do the same signal tests and report that all is OK. I've finally gotten a line tech who has a clue and is motivated enough to pursue this with me. We have tried things like switching the local nodes over to UPS and generator power, but this does not trigger the noise. We have tried replacing all cabling, the tap outside my house, the modem, the CATV decoder -- all without resolution. Recently they have decided it is both my computer or switch, my TiVo, and my phone that are all broken and causing this issue. My debugging steps I spent the worse day of my TV-watching life yesterday and part of today. I watched live TV without the TiVo. I witnessed blocking, but it did "feel different." and was actually more severe. Some days it is better, some days it is worse, so perhaps this was just a very bad day. Today, I connected the TiVo to my DVD player, and ran two very long movies through it. I saw no blocking at all during nearly 6 hours of video. Suggestions? Does anyone have any suggestions on what to do next? I understand perhaps only the IP side can be addressed here, but it is one of the more limiting debugging options.

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• Raid 1 array won't assemble after power outage. How do I fix this ext4 mirror?

  - by Forkrul Assail

  Two ext4 drives on Raid 1 with mdadm won't reassemble after the power went out for an extended period (UPS drained). After turning the machine back on, mdadm said that the array was degraded, after which it took about 2 days for a full resync, which completed without problems. On trying to remount the array I get: mount: you must specify the filesystem type cat /etc/fstab lines relevant to setup: /dev/md127 /media/mediapool ext4 defaults 0 0 dmesg | tail (on trying to mount) says: [ 1050.818782] EXT3-fs (md127): error: can't find ext3 filesystem on dev md127. [ 1050.849214] EXT4-fs (md127): VFS: Can't find ext4 filesystem [ 1050.944781] FAT-fs (md127): invalid media value (0x00) [ 1050.944782] FAT-fs (md127): Can't find a valid FAT filesystem [ 1058.272787] EXT2-fs (md127): error: can't find an ext2 filesystem on dev md127. cat /proc/mdstat says: Personalities : [raid1] [linear] [multipath] [raid0] [raid6] [raid5] [raid4] [raid10] md127 : active (auto-read-only) raid1 sdj[2] sdi[0] 2930135360 blocks super 1.2 [2/2] [UU] unused devices: <none> fsck /dev/md127 says: fsck from util-linux 2.20.1 e2fsck 1.42 (29-Nov-2011) fsck.ext2: Superblock invalid, trying backup blocks... fsck.ext2: Bad magic number in super-block while trying to open /dev/md127 The superblock could not be read or does not describe a correct ext2 filesystem. If the device is valid and it really contains an ext2 filesystem (and not swap or ufs or something else), then the superblock is corrupt, and you might try running e2fsck with an alternate superblock: e2fsck -b 8193 <device> mdadm -E /dev/sdi gives me: /dev/sdi: Magic : a92b4efc Version : 1.2 Feature Map : 0x0 Array UUID : 37ac1824:eb8a21f6:bd5afd6d:96da6394 Name : sojourn:33 Creation Time : Sat Nov 10 10:43:52 2012 Raid Level : raid1 Raid Devices : 2 Avail Dev Size : 5860271016 (2794.40 GiB 3000.46 GB) Array Size : 2930135360 (2794.39 GiB 3000.46 GB) Used Dev Size : 5860270720 (2794.39 GiB 3000.46 GB) Data Offset : 262144 sectors Super Offset : 8 sectors State : clean Device UUID : 3e6e9a4f:6c07ab3d:22d47fce:13cecfd0 Update Time : Tue Nov 13 20:34:18 2012 Checksum : f7d10db9 - correct Events : 27 Device Role : Active device 0 Array State : AA ('A' == active, '.' == missing) boot@boot ~ $ sudo mdadm -E /dev/sdj /dev/sdj: Magic : a92b4efc Version : 1.2 Feature Map : 0x0 Array UUID : 37ac1824:eb8a21f6:bd5afd6d:96da6394 Name : sojourn:33 Creation Time : Sat Nov 10 10:43:52 2012 Raid Level : raid1 Raid Devices : 2 Avail Dev Size : 5860271016 (2794.40 GiB 3000.46 GB) Array Size : 2930135360 (2794.39 GiB 3000.46 GB) Used Dev Size : 5860270720 (2794.39 GiB 3000.46 GB) Data Offset : 262144 sectors Super Offset : 8 sectors State : clean Device UUID : 7fb84af4:e9295f7b:ede61f27:bec0cb57 Update Time : Tue Nov 13 20:34:18 2012 Checksum : b9d17fef - correct Events : 27 Device Role : Active device 1 Array State : AA ('A' == active, '.' == missing) machine@user ~ dmesg | tail [ 61.785866] init: alsa-restore main process (2736) terminated with status 99 [ 68.433548] eth0: no IPv6 routers present [ 534.142511] EXT4-fs (sdi): ext4_check_descriptors: Block bitmap for group 0 not in group (block 2838187772)! [ 534.142518] EXT4-fs (sdi): group descriptors corrupted! [ 546.418780] EXT2-fs (sdi): error: couldn't mount because of unsupported optional features (240) [ 549.654127] EXT3-fs (sdi): error: couldn't mount because of unsupported optional features (240) Since this is Raid 1 it was suggested that I try and mount or fsck the drives separately. After a long fsck on one drive, it ended with this as tail: Illegal double indirect block (2298566437) in inode 39717736. CLEARED. Illegal block #4231180 (2611866932) in inode 39717736. CLEARED. Error storing directory block information (inode=39717736, block=0, num=1092368): Memory allocation failed Recreate journal? yes Creating journal (32768 blocks): Done. *** journal has been re-created - filesystem is now ext3 again *** The drive however still doesn't want to mount: dmesg | tail [ 170.674659] md: export_rdev(sdc) [ 170.675152] md: export_rdev(sdc) [ 195.275288] md: export_rdev(sdc) [ 195.275876] md: export_rdev(sdc) [ 1338.540092] CE: hpet increased min_delta_ns to 30169 nsec [26125.734105] EXT4-fs (sdc): ext4_check_descriptors: Checksum for group 0 failed (43502!=37987) [26125.734115] EXT4-fs (sdc): group descriptors corrupted! [26182.325371] EXT3-fs (sdc): error: couldn't mount because of unsupported optional features (240) [27083.316519] EXT4-fs (sdc): ext4_check_descriptors: Checksum for group 0 failed (43502!=37987) [27083.316530] EXT4-fs (sdc): group descriptors corrupted! Please help me fix this. I never in my wildest nightmares thought a complete mirror would die this badly. Am I missing something? Suggestions on fixing this? Could someone explain why it would resync after the powerout, only to seemingly nuke the drive? Thanks for reading. Any help much appreciated. I've tried everything I can think of, including booting and filesystem checking with SystemRescue and Ubuntu liveboot discs.

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