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• What is a good design pattern / lib for iOS 5 to synchronize with a web service?

  - by Junto

  We are developing an iOS application that needs to synchronize with a remote server using web services. The existing web services have an "operations" style rather than REST (implemented in WCF but exposing JSON HTTP endpoints). We are unsure of how to structure the web services to best fit with iOS and would love some advice. We are also interested in how to manage the synchronization process within iOS. Without going into detailed specifics, the application allows the user to estimate repair costs at a remote site. These costs are broken down by room and item. If the user has an internet connection this data can be sent back to the server. Multiple photographs can be taken of each item, but they will be held in a separate queue, which sends when the connection is optimal (ideally wifi). Our backend application controls the unique ids for each room and item. Thus, each time we send these costs to the server, the server echoes the central database ids back, thus, that they can be synchronized in the mobile app. I have simplified this a little, since the operations contract is actually much larger, but I just want to illustrate the basic requirements without complicating matters. Firstly, the web service architecture: We currently have two operations: GetCosts and UpdateCosts. My assumption is that if we used a strict REST architecture we would need to break our single web service operations into multiple smaller services. This would make the services much more chatty and we would also have to guarantee a delivery order from the app. For example, we need to make sure that containing rooms are added before the item. Although this seems much more RESTful, our perception is that these extra calls are expensive connections (security checks, database calls, etc). Does the type of web api (operation over service focus) determine chunky vs chatty? Since this is mobile (3G), are we better handling lots of smaller messages, or a few large ones? Secondly, the iOS side. What is the current advice on how to manage data synchronization within the iOS (5) app itself. We need multiple queues and we need to guarantee delivery order in each queue (and technically, ordering between queues). The server needs to control unique ids and other properties and echo them back to the application. The application then needs to update an internal database and when re-updating, make sure the correct ids are available in the update message (essentially multiple inserts and updates in one call). Our backend has a ton of business logic operating on these cost estimates. We don't want any of this in the app itself. Currently the iOS app sends the cost data, and then the server echoes that data back with populated ids (and other data). The existing cost data is deleted and the echoed response data is added to the client database on the device. This is causing us problems, because any photos might not have been sent, but the original entity tree has been removed and replaced. Obviously updating the costs tree rather than replacing it would remove this problem, but I'm not sure if there are any nice xcode libraries out there to do such things. I welcome any advice you might have.

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• Checking form input data on submit with pure PHP [migrated]

  - by Leron

  I have some experience with PHP but I have never even try to do this wit pure PHP, but now a friend of mine asked me to help him with this task so I sat down and write some code. What I'm asking is for opinion if this is the right way to do this when you want to use only PHP and is there anything I can change to make the code better. Besides that I think the code is working at least with the few test I made with it. Here it is: <?php session_start(); // define variables and initialize with empty values $name = $address = $email = ""; $nameErr = $addrErr = $emailErr = ""; $_SESSION["name"] = $_SESSION["address"] = $_SESSION["email"] = ""; $_SESSION["first_page"] = false; if ($_SERVER["REQUEST_METHOD"] == "POST") { if (empty($_POST["name"])) { $nameErr = "Missing"; } else { $_SESSION["name"] = $_POST["name"]; $name = $_POST["name"]; } if (empty($_POST["address"])) { $addrErr = "Missing"; } else { $_SESSION["address"] = $_POST["address"]; $address = $_POST["address"]; } if (empty($_POST["email"])) { $emailErr = "Missing"; } else { $_SESSION["email"] = $_POST["email"]; $email = $_POST["email"]; } } if ($_SESSION["name"] != "" && $_SESSION["address"] != "" && $_SESSION["email"] != "") { $_SESSION["first_page"] = true; header('Location: http://localhost/formProcessing2.php'); //echo $_SESSION["name"]. " " .$_SESSION["address"]. " " .$_SESSION["email"]; } ?> <DCTYPE! html> <head> <style> .error { color: #FF0000; } </style> </head> <body> <form method="POST" action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]);?>"> Name <input type="text" name="name" value="<?php echo htmlspecialchars($name);?>"> <span class="error"><?php echo $nameErr;?></span> <br /> Address <input type="text" name="address" value="<?php echo htmlspecialchars($address);?>"> <span class="error"><?php echo $addrErr;?></span> <br /> Email <input type="text" name="email" value="<?php echo htmlspecialchars($email);?>"> <span class="error"><?php echo $emailErr;?></span> <br /> <input type="submit" name="submit" value="Submit"> </form> </body> </html>

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• E-Business Suite : Role of CHUNK_SIZE in Oracle Payroll

  - by Giri Mandalika

  Different batch processes in Oracle Payroll flow have the ability to spawn multiple child processes (or threads) to complete the work in hand. The number of child processes to fork is controlled by the THREADS parameter in APPS.PAY_ACTION_PARAMETERS view. THREADS parameter The default value for THREADS parameter is 1, which is fine for a single-processor system but not optimal for the modern multi-core multi-processor systems. Setting the THREADS parameter to a value equal to or less than the total number of [virtual] processors available on the system may improve the performance of payroll processing. However on the down side, since multiple child processes operate against the same set of payroll tables in HR schema, database may experience undesired consequences such as buffer busy waits and index contention, which results in giving up some of the gains achieved by using multiple child processes/threads to process the work. Couple of other action parameters, CHUNK_SIZE and CHUNK_SHUFFLE, help alleviate the database contention. eg., Set a value for THREADS parameter as shown below. CONNECT APPS/APPS_PASSWORD UPDATE PAY_ACTION_PARAMETERS SET PARAMETER_VALUE = DESIRED_VALUE WHERE PARAMETER_NAME = 'THREADS'; COMMIT; (I am not aware of any maximum value for THREADS parameter) CHUNK_SIZE parameter The size of each commit unit for the batch process is controlled by the CHUNK_SIZE action parameter. In other words, chunking is the act of splitting the assignment actions into commit groups of desired size represented by the CHUNK_SIZE parameter. The default value is 20, and each thread processes one chunk at a time -- which means each child process inserts or processes 20 assignment actions at any time. When multiple threads are configured, each thread picks up a chunk to process, completes the assignment actions and then picks up another chunk. This is repeated until all the chunks are exhausted. It is possible to use different chunk sizes in different batch processes. During the initial phase of processing, CHUNK_SIZE number of assignment actions are inserted into relevant table(s). When multiple child processes are inserting data at the same time into the same set of tables, as explained earlier, database may experience contention. The default value of 20 is mostly optimal in such a case. Experiment with different values for the initial phase by +/-10 for CHUNK_SIZE parameter and observe the performance impact. A larger value may make sense during the main processing phase. Again experimentation is the key in finding the suitable value for your environment. Start with a large value such as 2000 for the chunk size, then increment or decrement the size by 500 at a time until an optimal value is found. eg., Set a value for CHUNK_SIZE parameter as shown below. CONNECT APPS/APPS_PASSWORD UPDATE PAY_ACTION_PARAMETERS SET PARAMETER_VALUE = DESIRED_VALUE WHERE PARAMETER_NAME = 'CHUNK_SIZE'; COMMIT; CHUNK_SIZE action parameter accepts a value that is as low as 1 or as high as 16000. CHUNK SHUFFLE parameter By default, chunks of assignment actions are processed sequentially by all threads - which may not be a good thing especially given that all child processes/threads performing similar actions against the same set of tables almost at the same time. By saying not a good thing, I mean to say that the default behavior leads to contention in the database (in data blocks, for example). It is possible to relieve some of that database contention by randomizing the processing order of chunks of assignment actions. This behavior is controlled by the CHUNK SHUFFLE action parameter. Chunk processing is not randomized unless explicitly configured. eg., Set chunk shuffling as shown below. CONNECT APPS/APPS_PASSWORD UPDATE PAY_ACTION_PARAMETERS SET PARAMETER_VALUE = 'Y' WHERE PARAMETER_NAME = 'CHUNK SHUFFLE'; COMMIT; Finally I recommend checking the following document out for additional details and additional pay action tunable parameters that may speed up the processing of Oracle Payroll.     My Oracle Support Doc ID: 226987.1 Oracle 11i & R12 Human Resources (HRMS) & Benefits (BEN) Tuning & System Health Checks Also experiment with different combinations of parameters and values until the right set of action parameters and values are found for your deployment.

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• I am trying to figure out the best way to understand how to cache domain objects

  - by Brett Ryan

  I've always done this wrong, I'm sure a lot of others have too, hold a reference via a map and write through to DB etc.. I need to do this right, and I just don't know how to go about it. I know how I want my objects to be cached but not sure on how to achieve it. What complicates things is that I need to do this for a legacy system where the DB can change without notice to my application. So in the context of a web application, let's say I have a WidgetService which has several methods: Widget getWidget(); Collection<Widget> getAllWidgets(); Collection<Widget> getWidgetsByCategory(String categoryCode); Collection<Widget> getWidgetsByContainer(Integer parentContainer); Collection<Widget> getWidgetsByStatus(String status); Given this, I could decide to cache by method signature, i.e. getWidgetsByCategory("AA") would have a single cache entry, or I could cache widgets individually, which would be difficult I believe; OR, a call to any method would then first cache ALL widgets with a call to getAllWidgets() but getAllWidgets() would produce caches that match all the keys for the other method invocations. For example, take the following untested theoretical code. Collection<Widget> getAllWidgets() { Entity entity = cache.get("ALL_WIDGETS"); Collection<Widget> res; if (entity == null) { res = loadCache(); } else { res = (Collection<Widget>) entity.getValue(); } return res } Collection<Widget> loadCache() { // Get widgets from underlying DB Collection<Widget> res = db.getAllWidgets(); cache.put("ALL_WIDGETS", res); Map<String, List<Widget>> byCat = new HashMap<>(); for (Widget w : res) { // cache by different types of method calls, i.e. by category if (!byCat.containsKey(widget.getCategory()) { byCat.put(widget.getCategory(), new ArrayList<Widget>); } byCat.get(widget.getCatgory(), widget); } cacheCategories(byCat); return res; } Collection<Widget> getWidgetsByCategory(String categoryCode) { CategoryCacheKey key = new CategoryCacheKey(categoryCode); Entity ent = cache.get(key); if (entity == null) { loadCache(); } ent = cache.get(key); return ent == null ? Collections.emptyList() : (Collection<Widget>)ent.getValue(); } NOTE: I have not worked with a cache manager, the above code illustrates cache as some object that may hold caches by key/value pairs, though it's not modelled on any specific implementation. Using this I have the benefit of being able to cache all objects in the different ways they will be called with only single objects on the heap, whereas if I were to cache the method call invocation via say Spring It would (I believe) cache multiple copies of the objects. I really wish to try and understand the best ways to cache domain objects before I go down the wrong path and make it harder for myself later. I have read the documentation on the Ehcache website and found various articles of interest, but nothing to give a good solid technique. Since I'm working with an ERP system, some DB calls are very complicated, not that the DB is slow, but the business representation of the domain objects makes it very clumsy, coupled with the fact that there are actually 11 different DB's where information can be contained that this application is consolidating in a single view, this makes caching quite important.

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• Notes - Part II - Play with JavaFX

  - by Silviu Turuga

  Open the project from last lesson Double click on NotesUI.fmxl, this will open the JavaFX Scene Builder On the left side you have a area called Hierarchy, from there press Del or Shift+Backspace on Mac to delete the Button and the Label. You'll receive a warning, that some components have been assigned an fx:id, click Delete as we don't need them anymore. Resize the AnchorPane to have enough room for our design, eg. 820x550px From the top left pick the Container called Accordion and drag over the AnchorPane design Chose then from Controls a List View and drag inside the Accordion. You'll notice that by default the Accordion has 2 TitledPane, and you can switch between them by clicking on their name. I'll let you the pleasure to do the rest in order to get the following result  Here is the list of objects used Save it and then return to NetBeans Run the application and it should be run without any issue. If you click on buttons they all are functional, but nothing happens as we didn't link them with any action. We'll see this in the next episode. Now, let's play a little bit with the application and try to resize it… Have you notice the behavior? If the form is too small, some objects aren't visible, if it is too large there is too much space . That's for sure something that your users won't like and you as a programmer have to care about this. From NetBeans double click NotesUI.fmxl so to return back to JavaFX Scene Builder Select the TextField from bottom left of Notes, the one where I put the text Category and then from the right part of JavaFX Scene Builder you'll notice a panel called Inspector. Chose Layout and then click on the dotted lines from left and bottom of the square, like you see in the below image This will make the textfield to have always the same distance from left and bottom no matter the size of the form. Save and run the application. Note that whenever the form is changing the Height, the Category TextField has the same distance from the bottom. Select Accordion and do the same steps but also check the top dotted line, because we want the Accordion to have the same height as the main form has. I'll let you the pleasure to do the same for the rest of components. It's very important to design an application that can be resize by user and in the same time, all the buttons are on place. Last step is to make sure our application is not getting smaller then a certain size, as this will hide parts of our layout. So select the AnchorPane and from Inspector go to Layout and note down the Width and Height. Go back to NetBeans and open the file Main.java and add the following code just after stage.setScene(scene); (around line 26) stage.setMinWidth(820); stage.setMinHeight(550); Use your own width and height. This will prevent user to reduce the width or height of your application to a value that will hide parts of your layout. So now you should have done most of the design part and next time we'll see how can we enter some data into our newly created application… Note: in case you miss something, here are the source files of the project till this point. 

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• How much is a subscriber worth?

  - by Tom Lewin

  This year at Red Gate, we’ve started providing a way to back up SQL Azure databases and Azure storage. We decided to sell this as a service, instead of a product, which means customers only pay for what they use. Unfortunately for us, it makes figuring out revenue much trickier. With a product like SQL Compare, a customer pays for it, and it’s theirs for good. Sure, we offer support and upgrades, but, fundamentally, the sale is a simple, upfront transaction: we’ve made this product, you need this product, we swap product for money and everyone is happy. With software as a service, it isn’t that easy. The money and product don’t change hands up front. Instead, we provide a service in exchange for a recurring fee. We know someone buying SQL Compare will pay us $X, but we don’t know how long service customers will stay with us, or how much they will spend. How do we find this out? We use lifetime value analysis. What is lifetime value? Lifetime value, or LTV, is how much a customer is worth to the business. For Entrepreneurs has a brilliant write up that we followed to conduct our analysis. Basically, it all boils down to this equation: LTV = ARPU x ALC To make it a bit less of an alphabet-soup and a bit more understandable, we can write it out in full: The lifetime value of a customer equals the average revenue per customer per month, times the average time a customer spends with the service Simple, right? A customer is worth the average spend times the average stay. If customers pay on average $50/month, and stay on average for ten months, then a new customer will, on average, bring in $500 over the time they are a customer! Average spend is easy to work out; it’s revenue divided by customers. The problem comes when we realise that we don’t know exactly how long a customer will stay with us. How can we figure out the average lifetime of a customer, if we only have six months’ worth of data? The answer lies in the fact that: Average Lifetime of a Customer = 1 / Churn Rate The churn rate is the percentage of customers that cancel in a month. If half of your customers cancel each month, then your average customer lifetime is two months. The problem we faced was that we didn’t have enough data to make an estimate of one month’s cancellations reliable (because barely anybody cancels)! To deal with this data problem, we can take data from the last three months instead. This means we have more data to play with. We can still use the equation above, we just need to multiply the final result by three (as we worked out how many three month periods customers stay for, and we want our answer to be in months). Now these estimates are likely to be fairly unreliable; when there’s not a lot of data it pays to be cautious with inference. That said, the numbers we have look fairly consistent, and it’s super easy to revise our estimates when new data comes in. At the very least, these numbers give us a vague idea of whether a subscription business is viable. As far as Cloud Services goes, the business looks very viable indeed, and the low cancellation rates are much more than just data points in LTV equations; they show that the product is working out great for our customers, which is exactly what we’re looking for!

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• Customer owes me half my payment. Should I take ownership of his AWS account for charging? How?

  - by Cawas

  Background They paid me my first half (back in April 15th) before even we could get into an agreement. Very nice of him! Then I've finished the 2 weeks job of setting up the servers, using his AWS credentials he had just bought. I waited for another 2 weeks for everything settling up, and it was all running fine. He did what he needed with his sftp account, everyone were happy. Now, it has been almost 2 months since I've finished the job and I still didn't get the 2nd half. I must assume, it's not much money (about U$400, converted), but it would help me pay the bills at least. Heck, the Amazon bills they are paying are little less than that (for now). Measures I'm wondering how I can go to charge him now. First thought, of course, would be taking everything down and say "pay now, or be doomed". If that's not good enough, then I lost it. I have no contracts and I doubt I could get a law suit in this country for such a low value based only on emails. And I don't really want to get too agressive here - there might be a business chance in the future and I don't want to ruin it. Second though would be just changing the password. But then he probably could gain access again by some recovery means. That's where my question may mainly relay. How can I do it and not leaving any room for recovery from his side? I even got the first AWS "your account was created" mail from himself, showing me I could begin my job, back then. Lastly, do you have any other idea on what I can and what I should do in this case? Responding to Answers Please, consider reading the current answers and comments. This is not a very simple case. I've considered many, many options (including all lawful ones) before considering this ones I've listed here, and I am willing to take the loss and all that. That's not the point. The point is being practical here. I will call him again and talk about it. I will do terrorism on getting lawyers and getting contract. I am ready to go all forth while I have time and energy for it. But, in practice, there is this extra thing I can do to assure myself of the work I've done. I can basically take it back and delete everything! I'd only take his password because I can find no other way to do it within Amazon. Maybe, contacting Amazon and explaining the situation? I don't know. Give me ideas on this technical side! And thank everyone for the attention and helping me clarifying the issue so far! :)

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• The Social Enterprise: Gangnam Style

  - by Mike Stiles

  Are only small and medium businesses able to put social strategies in place, generate consistent, compelling content for customers, and be nimble enough to listen and respond to the social communities they build? Or are enterprise organizations eagerly and effectively adopting social as well? It depends on whom inside the organization you ask. A study from Attensity looked at who “gets” social inside enterprise organizations. The results were unsurprising. Mostly, Generation X and Y employees who came of age with social as part of their lives and as a key communications vehicle understand it. Imagine being a 25-year-old at a company that bans employees from accessing Facebook at work. You may as well tell them they can’t use phones and must do all calculations on an abacus. To them, such policy is absent of real-world logic and signals to them the organization is destined to be the victim of an up-and-comer. After that, it’s senior management that gets social. You don’t get to be in senior management without reading a few things and paying attention. Most senior managers are well aware of the impact social has had and will have, though they may be unsure of what to do about it. The better ones will utilize those on the inside who do inherently know how to communicate and build virtual relationships using social. The very best will get the past out of the way for these social innovators, so the new communications can be enacted minus counterproductive dictums, double-clutching, meeting-creep, and all the other fading internal practices that water down content and impede change. Organizationally, the Attensity study found 81% of enterprise companies believe failing to embrace social will result in their being left behind. Yet our old friend fear still has many captive in its clutches. 79% feel overwhelmed by the volume of social data available, something a social technology partner with goal-oriented analytics expertise could go a long way toward alleviating. Then there’s the fear of social having a negative impact. This comes from a lack of belief in the product, the customer service, or both. The public uses social not to go out and slay brands. They’re using it to be honest. If the fear is that honesty will reflect badly on the brand, the brand has much bigger, broader problems than what happens on Facebook. Sadly, most enterprise organizations still see social as a megaphone, a one-way channel with which to hit people with ads. They either don’t understand social relationships, or don’t want any. The truly unenlightened manager will always say, “We help them by selling them our stuff.” “Brand affinity” is a term, it’s just not one assigned much value in enterprise organizations. Which brings us to Psy, the Korean performer whose Internet video phenom “Gangnam Style,” as of this writing, has been viewed 438,550,238 times on YouTube. It’s bigger than anything a brand will probably ever publish. Most brands would never have seen the point of making or publishing it. But a funny thing happened on the way to Internet success. The video literally doubled the stock price of Psy’s father’s software firm. NH Investment and Securities said, "The positive sentiment has attracted investors just because of the fact the company is owned by Psy's father and uncle.” The company wasn’t mentioned or seen in the video in any way, yet reaped tangible rewards just for being tangentially associated with it. Imagine your brand being visibly and directly responsible for such a smash and tell me it’s worthless. When enterprise organizations embrace the value of igniting passions, making people happier, solving their problems, informing them, helping them have fun, etc., then they will have fully embraced social, and will reap the brand affinity rewards of heightened awareness, brand loyalty and yes, sales.

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• 2D Tile based Game Collision problem

  - by iNbdy

  I've been trying to program a tile based game, and I'm stuck at the collision detection. Here is my code (not the best ^^): void checkTile(Character *c, int **map) { int x1,x2,y1,y2; /* Character position in the map */ c->upY = (c->y) / TILE_SIZE; // Top left corner c->downY = (c->y + c->h) / TILE_SIZE; // Bottom left corner c->leftX = (c->x) / TILE_SIZE; // Top right corner c->rightX = (c->x + c->w) / TILE_SIZE; // Bottom right corner x1 = (c->x + 10) / TILE_SIZE; // 10px from left side point x2 = (c->x + c->w - 10) / TILE_SIZE; // 10px from right side point y1 = (c->y + 10) / TILE_SIZE; // 10px from top side point y2 = (c->y + c->h - 10) / TILE_SIZE; // 10px from bottom side point /* Top */ if (map[c->upY][x1] > 2 || map[c->upY][x2] > 2) c->topCollision = 1; else c->topCollision = 0; /* Bottom */ if ((map[c->downY][x1] > 2 || map[c->downY][x2] > 2)) c->downCollision = 1; else c->downCollision = 0; /* Left */ if (map[y1][c->leftX] > 2 || map[y2][c->leftX] > 2) c->leftCollision = 1; else c->leftCollision = 0; /* Right */ if (map[y1][c->rightX] > 2 || map[y2][c->rightX] > 2) c->rightCollision = 1; else c->rightCollision = 0; } That calculates 8 collision points My moving function is like that: void movePlayer(Character *c, int **map) { if ((c->dirX == LEFT && !c->leftCollision) || (c->dirX == RIGHT && !c->rightCollision)) c->x += c->vx; if ((c->dirY == UP && !c->topCollision) || (c->dirY == DOWN && !c->downCollision)) c->y += c->vy; checkPosition(c, map); } and the checkPosition: void checkPosition(Character *c, int **map) { checkTile(c, map); if (c->downCollision) { if (c->state != JUMPING) { c->vy = 0; c->y = (c->downY * TILE_SIZE - c->h); } } if (c->leftCollision) { c->vx = 0; c->x = (c->leftX) * TILE_SIZE + TILE_SIZE; } if (c->rightCollision) { c->vx = 0; c->x = c->rightX * TILE_SIZE - c->w; } } This works, but sometimes, when the player is landing on ground, right and left collision points become equal to 1. So it's as if there were collision coming from left or right. Does anyone know why this is doing this?

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• Move over DFS and Robocopy, here is SyncToy!

  - by andywe

  Ever since Windows 2000, I have always had the need to replicate data to multiple endpoints with the same content. Until DFS was introduced, the method of thinking was to either manually copy the data location by location, or to batch script it with xcopy and schedule a task. Even though this worked (and still does today), it was cumbersome, and intensive on the network, especially when dealing with larger amounts of data. Then along came robocopy, as an internal tool written by an enterprising programmer at Microsoft. We used it quite a bit, especially when we could not use DFS in the early days. It was received so well, it made it into the public realm. At least now we could have the ability to determine what files had changed and only replicate those. Well, over time there has been evolution of this ideal. DFS is obviously the Windows enterprise class service to do this, along with BrancheCache..however you don’t always need or want the power of DFS, especially when it comes to small datacenter installations, or remote offices. I have specific data sets that are on closed or restricted networks, that either have a security need for this, or are in remote countries where bandwidth is a premium. FOr this, I use the latest evolution for one off replication names Synctoy. Synctoy is from Microsoft, seemingly released in 2009, that wraps a nice GUI around setting up a paired set of folders (remember the mobile briefcase from Windows 98?), and allowing you the choice of synchronization methods. 1 way, or 2 way. Simply create a paired set of folders on the source and destination, choose your options for content, exclude any file types you don’t want to replicate, and click run. Scheduling is even easier. MS has included a wrapper for doing just this so all you enter in your task schedule in the SynToyCMD.exe, a –R as an argument, and the time schedule. No more complicated command lines or scripts.   I find this especially useful when I use MS backup to back up a system volume, but only want subsets of backup information of a data share and ONLY when that dataset has changed. Not relying on full backups and incremental. An example of this is my application installation master share. I back this up with SyncToy because I do not need multiple backup copies..one copy elsewhere suffices to back it up. At home, very useful for your pictures, videos, music, ect..the backup is online and ready to access, not waiting for you to restore a backup file, and no need to institute a domain simply to have DFS.'   Do note there is a risk..if you accidently delete a file and do not catch this before the next sync, then depending on your SyncToy settings, you can indeed lose that file as the destination updates..so due diligence applies. I make it a rule to sync manly one way…I use my master share for making changes, and allow the schedule to follow suit. Any real important file I lock down as read only through file permissions so it cannot be deleted unless I intervene.   Check out the tool and have some fun! http://www.microsoft.com/en-us/download/details.aspx?DisplayLang=en&id=15155

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• Omni-directional light shadow mapping with cubemaps in WebGL

  - by Winged

  First of all I must say, that I have read a lot of posts describing an usage of cubemaps, but I'm still confused about how to use them. My goal is to achieve a simple omni-directional (point) light type shading in my WebGL application. I know that there is a lot more techniques (like using Two-Hemispheres or Camera Space Shadow Mapping) which are way more efficient, but for an educational purpose cubemaps are my primary goal. Till now, I have adapted a simple shadow mapping which works with spotlights (with one exception: I don't know how to cut off the glitchy part beyond the reach of a single shadow map texture): glitchy shadow mapping<<< So for now, this is how I understand the usage of cubemaps in shadow mapping: Setup a framebuffer (in case of cubemaps - 6 framebuffers; 6 instead of 1 because every usage of framebufferTexture2D slows down an execution which is nicely described here <<<) and a texture cubemap. Also in WebGL depth components are not well supported, so I need to render it to RGBA first. this.texture = gl.createTexture(); gl.bindTexture(gl.TEXTURE_CUBE_MAP, this.texture); gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_MIN_FILTER, gl.LINEAR); gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_MAG_FILTER, gl.LINEAR); for (var face = 0; face < 6; face++) gl.texImage2D(gl.TEXTURE_CUBE_MAP_POSITIVE_X + face, 0, gl.RGBA, this.size, this.size, 0, gl.RGBA, gl.UNSIGNED_BYTE, null); gl.bindTexture(gl.TEXTURE_CUBE_MAP, null); this.framebuffer = []; for (face = 0; face < 6; face++) { this.framebuffer[face] = gl.createFramebuffer(); gl.bindFramebuffer(gl.FRAMEBUFFER, this.framebuffer[face]); gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_CUBE_MAP_POSITIVE_X + face, this.texture, 0); gl.framebufferRenderbuffer(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.RENDERBUFFER, this.depthbuffer); var e = gl.checkFramebufferStatus(gl.FRAMEBUFFER); // Check for errors if (e !== gl.FRAMEBUFFER_COMPLETE) throw "Cubemap framebuffer object is incomplete: " + e.toString(); } Setup the light and the camera (I'm not sure if should I store all of 6 view matrices and send them to shaders later, or is there a way to do it with just one view matrix). Render the scene 6 times from the light's position, each time in another direction (X, -X, Y, -Y, Z, -Z) for (var face = 0; face < 6; face++) { gl.bindFramebuffer(gl.FRAMEBUFFER, shadow.buffer.framebuffer[face]); gl.viewport(0, 0, shadow.buffer.size, shadow.buffer.size); gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT); camera.lookAt( light.position.add( cubeMapDirections[face] ) ); scene.draw(shadow.program); } In a second pass, calculate the projection a a current vertex using light's projection and view matrix. Now I don't know If should I calculate 6 of them, because of 6 faces of a cubemap. ScaleMatrix pushes the projected vertex into the 0.0 - 1.0 region. vDepthPosition = ScaleMatrix * uPMatrixFromLight * uVMatrixFromLight * vWorldVertex; In a fragment shader calculate the distance between the current vertex and the light position and check if it's deeper then the depth information read from earlier rendered shadow map. I know how to do it with a 2D Texture, but I have no idea how should I use cubemap texture here. I have read that texture lookups into cubemaps are performed by a normal vector instead of a UV coordinate. What vector should I use? Just a normalized vector pointing to the current vertex? For now, my code for this part looks like this (not working yet): float shadow = 1.0; vec3 depth = vDepthPosition.xyz / vDepthPosition.w; depth.z = length(vWorldVertex.xyz - uLightPosition) * linearDepthConstant; float shadowDepth = unpack(textureCube(uDepthMapSampler, vWorldVertex.xyz)); if (depth.z > shadowDepth) shadow = 0.5; Could you give me some hints or examples (preferably in WebGL code) how I should build it?

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• Hyper-V for Developers Part 1 Internal Networks

  Over the last year, weve been working with Microsoft to build training and demo content for the next version of Office Communications Server code-named Microsoft Communications Server 14.  This involved building multi-server demo environments in Hyper-V, getting them running on demo servers which we took to TechEd, PDC, and other training events, and sometimes connecting the demo servers to the show networks at those events.  ITPro stuff that should scare the hell out of a developer! It can get ugly when I occasionally have to venture into ITPro land.  Lets leave it at that. Having gone through this process about 10 to 15 times in the last year, I finally have it down.  This blog series is my attempt to put all that knowledge in one place if anything, so I can find it somewhere when I need it again.  Ill start with the most simple scenario and then build on top of it in future blog posts. If youre an ITPro, please resist the urge to laugh at how trivial this is. Internal Hyper-V Networks Lets start simple.  An internal network is one that intended only for the virtual machines that are going to be on that network it enables them to communicate with each other. Create an Internal Network On your host machine, fire up the Hyper-V Manager and click the Virtual Network Manager in the Actions panel. Select Internal and leave all the other default values. Give the virtual network a name, and leave all the other default values. After the virtual network is created, open the Network and Sharing Center and click Change Adapter Settings to see the list of network connections. The only thing I recommend that you do is to give this connection a friendly label, e.g. Hyper-V Internal.  When you have multiple networks and virtual networks on the host machines, this helps group the networks so you can easily differentiate them from each other.  Otherwise, dont touch it, only bad things can happen. Connect the Virtual Machines to the Internal Network Im assuming that you have more than 1 virtual machine already configured in Hyper-V, for example a Domain Controller, and Exchange Server, and a SharePoint Server. What you need to do is basically plug in the network to the virtual machine.  In order to do this, the machine needs to have a virtual network adapter.  If the VM doesnt have a network adapter, open the VMs Settings and click Add Hardware in the left pane.  Choose the virtual network to which to bind the adapter to. If you already have a virtual network adapter on the VM, simply connect it to the virtual network. Assign IP Addresses to the Virtual Machines on the Internal Network Open the Network and Sharing Center on your VM, there should only be 1 network at this time.  Open the Properties of the connection, select Internet Protocol Version 4 (TCP/IPv4) and hit Properties. In this environment, Im assigning IP addresses as 192.168.0.xxx.  This particular VM has an IP address of 192.168.0.40 with a subnet mask of 255.255.255.0, and a DNS Server of 192.168.0.18.  DNS is running on the Domain Controller VM which has an IP address of 192.168.0.18. Repeat this process on every VM in your environment, obviously assigning a unique IP address to each.  In an environment with a domain controller, you should now be able to ping the machines from each other. What Next? After completing this process, heres what you still cannot do: Access the internet from any of the VMs Remote desktop to a VM from the host Remote desktop to a VM over the network In the next post, well take a look configuring an External network adapter on the virtual machines.  Well then build on top of that so that you can RDP into the VMs from the host machine and over the network.Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• DBA Best Practices - A Blog Series: Episode 2 - Password Lists

  - by Argenis

    Digital World, Digital Locks One of the biggest digital assets that any company has is its secrets. These include passwords, key rings, certificates, and any other digital asset used to protect another asset from tampering or unauthorized access. As a DBA, you are very likely to manage some of these assets for your company - and your employer trusts you with keeping them safe. Probably one of the most important of these assets are passwords. As you well know, the can be used anywhere: for service accounts, credentials, proxies, linked servers, DTS/SSIS packages, symmetrical keys, private keys, etc., etc. Have you given some thought to what you're doing to keep these passwords safe? Are you backing them up somewhere? Who else besides you can access them? Good-Ol’ Post-It Notes Under Your Keyboard If you have a password-protected Excel sheet for your passwords, I have bad news for you: Excel's level of encryption is good for your grandma's budget spreadsheet, not for a list of enterprise passwords. I will try to summarize the main point of this best practice in one sentence: You should keep your passwords on an encrypted, access and version-controlled, backed-up, well-known shared location that every DBA on your team is aware of, and maintain copies of this password "database" on your DBA's workstations. Now I have to break down that statement to you: - Encrypted: what’s the point of saving your passwords on a file that any Windows admin with enough privileges can read? - Access controlled: This one is pretty much self-explanatory. - Version controlled: Passwords change (and I’m really hoping you do change them) and version control would allow you to track what a previous password was if the utility you’ve chosen doesn’t handle that for you. - Backed-up: You want a safe copy of the password list to be kept offline, preferably in long term storage, with relative ease of restoring. - Well-known shared location: This is critical for teams: what good is a password list if only one person in the team knows where it is? I have seen multiple examples of this that work well. They all start with an encrypted database. Certainly you could leverage SQL Server's native encryption solutions like cell encryption for this. I have found such implementations to be impractical, for the most part. Enter The World Of Utilities There are a myriad of open source/free software solutions to help you here. One of my favorites is KeePass, which creates encrypted files that can be saved to a network share, Sharepoint, etc. KeePass has UIs for most operating systems, including Windows, MacOS, iOS, Android and Windows Phone. Other solutions I've used before worth mentioning include PasswordSafe and 1Password, with the latter one being a paid solution – but wildly popular in mobile devices. There are, of course, even more "enterprise-level" solutions available from 3rd party vendors. The truth is that most of the customers that I work with don't need that level of protection of their digital assets, and something like a KeePass database on Sharepoint suits them very well. What are you doing to safeguard your passwords? Leave a comment below, and join the discussion! Cheers, -Argenis

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• Web Services Example - Part 1: Declarative

  - by Denis T

  In this edition of the ADF Mobile blog we'll tackle part 1 of our Web Service examples. In this posting we'll take a look at using a declarative SOAP Web Service. Getting the sample code: Just click here to download a zip of the entire project. You can unzip it and load it into JDeveloper and deploy it either to iOS or Android. Please follow the previous blog posts if you need help getting JDeveloper or ADF Mobile installed. Defining our Web Service: First off, we should mention that this sample code is using a public web service provided free by CDYNE Corporation that provides weather forecasts by zipcode. Sometimes this service goes down so please ensure you know it's up before reporting this example isn't working. Let's take a look at the web service.  We created this by using the "Web Service Data Control" from the New Gallery and using this link to this wsdl:  "http://wsf.cdyne.com/WeatherWS/Weather.asmx?WSDL"   This web service has several methods but we're interested in GetCityForecastByZIP which takes a single string parameter for the zipcode and the second method, GetWeatherInformation that enumerates all possible forecast descriptions and associated image URLs.  The latter we'll use in the next edition but we included it here for completeness. Defing the Application: After adding a feature to the adfmf-feature.xml file, we added a taskflow to host the application flow.  This comprises of a home screen with a list with items for each method in the web service, "Forecast by Zip" and "Weather Info".  In this application we've also decided to hide the navigation bar since there is only one feature in the application. Forecast by Zip: The "Forecast By ZIP" option first presents the user with a screen where they can enter a zipcode and when the "Search" button is tapped, it executes the GetCityForecastByZIP method.  This is done by binding an Action binding to that method. The easiest way to accomplish this is to just drag & drop the method from the Data Control palette to the AMX page and drop it as a button and let the framework hook it up for you.  There is an inputText component on the page that is bound to a pageFlowScope variable called "zip".  This is used as the parameter to the Action binding when it is executed.  Because the actionListener attribute of the commandButton executes the Web Service each time, we ensure that the method is invoked every time the button is clicked. Weather Info: Unlike the previous method, this time instead of explictly executing the web service method we are using deferred invocation.  What this means is that we will bind to the results of the method and the framework will execute the method when it the data is required to be rendered.  We do this by simply doing a drag & drop of the results of the GetWeatherInformation to the AMX page.  When the page is rendered and the bindings are resolved the framework invokes the method.  This executes the method only when it is needed and fills the Data Control provider.  Because we never re-execute the method, you can click from Home to Weather Info and back many times and the web service is only ever invoked once. Issues and Possible Improvements: One thing you will quickly realize with this example is that the error handling is done by the framework for you. For simple examples this is fine but for real applications you'll want to customize these error messages.  With the declarative invocation of web services, this is difficult.  This is one aspect we'll address in the second installment of the web service examples where we will show you how to do programmatic invocation which allows you better error handling. Another issue you will notice with this example is that we can enumerate the weather information but there isn't an easy way to use that information to show the corresponding description and image as part of the forecast results.  We'll show you how to do this in the next example.

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• Test your internet connection - Emtel Fixed Broadband

  Already at the begin of April, I had a phone conversation with my representative at Emtel Ltd. about some upcoming issues due to the ongoing construction work in my neighbourhood. Unfortunately, they finally raised the house two levels above ours, and of course this has to have a negative impact on the visibility between the WiMAX outdoor unit on the roof and the aimed access point at Medine. So, today I had a technical team here to do a site survey and to come up with potential solutions. Short version: It doesn't look good after all. The site survey Well, the two technicians did their work properly, even re-arranged the antenna to check the connection with another end point down at La Preneuse. But no improvements. Looks like we are out of luck since the construction next door hasn't finished yet and at the moment, it even looks like they are planning to put at least one more level on top. I really wonder about the sanity of the responsible bodies at the local district council. But that's another story. Anyway, the outdoor unit was once again pointed towards Medine and properly fixed with new cable guides (air from the sea and rust...). Both of them did a good job and fine-tuned the reception signal to a mere 3 over 9; compared to the original 7 over 9 I had before the daily terror started. The site survey has been done, and now it's up to Emtel to come up with (better) solutions. Well, I wouldn't mind to have an unlimited, symmetric 3G/UMTS or even LTE connection. Let's see what they can do... Testing the connection There are several online sites available which offer you to check certain aspects of your internet connection. Personally, I'm used to speedtest.net and it works very well. I think it is good and necessary to check your connection from time to time, and only a couple of days ago, I posted the following on Emtel's wall at Facebook (21.05.2013 - 14:06 hrs): Dear Emtel, could you eventually provide an answer on the miserable results of SpeedTest? I chose Rose Hill (Hosted by Emtel Ltd.) as testing endpoint... Sadly, no response to this. Seems that the marketing department is not willing to deal with customers on Facebook. Okay, over at speedtest.net you can use their Flash-based test suite to check your connection to quite a number of servers of different providers world-wide. It's actually very interesting to see the results for different end points and to compare them to each other. The results Following are the results of Rose Hill (hosted by Emtel) and respectively Frankfurt, Germany (hosted by Vodafone DE): Speedtest.net result of 30.05.2013 between Flic en Flac and Rose Hill, Mauritius (Emtel - Fixed Broadband) Speedtest.net result of 30.05.2013 between Flic en Flac and Frankfurt, Germany (Emtel - Fixed Broadband) Luckily, the results are quite similar in terms of connection speed; which is good. I'm currently on a WiMAX tariff called 'Classic Browsing 2', or Fixed Broadband as they call it now, which provides a symmetric line of 768 Kbps (or roughly 0.75 Mbps). In terms of downloads or uploads this means that I would be able to transfer files in either direction with approximately 96 KB/s. Frankly speaking, thanks to compression, my choice of browser and operating system I usually exceed this value and I have download rates up to 120 KB/s - not too bad after all. Only the ping times are a little bit of concern. Due to the difference in distance, or better said based on the number of hubs between the endpoints, they indicate the amount of time that it takes to send a package from your machine to the remote server and get a response back. A lower value is better, and usually the ping is less than 300 ms between Mauritius and Europe. The alternatives in Mauritius Not sure whether I should note this done because for my requirements there are no alternatives to Emtel WiMAX at the moment. It would be great to have your opinion on the situation of internet connectivity in Mauritius. Are there really alternatives? And if so, what are the conditions?

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• Free hosting solution for a very low-traffic website [duplicate]

  - by user966939

  This question already has an answer here: How to find web hosting that meets my requirements? 4 answers I run a very low-traffic website (about 40 users, basically all of which are daily active on the site). I don't see it changing anytime soon either, as there is no way to sign up on the site right now. Until now I have just been using a sub-directory on a friend's host (shared), to host the web site. But in only a few weeks from now, his subscription will end, and he has no plans on renewing it. So of course this means I'll have to move on to something else. But I don't think I'll find someone who'd be willing to share a... shared host with me again. And besides, the software used on that server is ancient (PHP 4.4.9 + MySQL 4.1.22). There's one obvious solution that comes to mind, I guess: choose a better host and pay for it myself. The problem here is that I have no real fixed income, as I'm only a student. So even if the pricing is dirt cheap, I just can't be certain I will be able to afford it, every single month, for... at least 2 years maybe? So I've looked at free hosting solutions instead. The least requirement I had was that it was completely free of ads. But no matter where I look, I always find something in a corner or two ("what can you expect from a free host?" - yeah I know, but I guess it was worth a shot). For example, on Byethost (one of the free hosts I tried), if you trigger a PHP error while error reporting is set to E_ALL, you will spawn some hidden ad... Besides Byethost, I've tried 000Webhost, x10Hosting, 2Freehosting/1Freehosting, Wink.ws, and they are only worse. Okay, I'm running low on ideas. But! What if I just hosted the site myself, on my own computer? That could work. I actually do have my computer on practically 24/7. But not really. Sometimes I need to reboot it, and sometimes we even have power outages. And what if the hardware needs an upgrade? It's not such a big deal for me if the site went down, because I know what's going on; but what about the users? If I do decide to host it myself, is there some way to show users an alternate page instead of them just seeing a generic "server not found" page in the browser when the site is not accessible? Or is there something I have been missing out on? Is there a different kind of "web hosting" solution out there that I haven't heard of? Here is what I'm really looking for: Free (as in, no costs) NO ads Bandwidth enough for a low-traffic forum with roughly 40 users (Semi-)Up-to-date PHP and MySQL (at least not older than a year) No standard (non-extension) PHP functions turned off - such as sleep() The mbstring extension is enabled Disk space: at least 5 MB At least one MySQL database Some bonus points would be: Max execution time of PHP scripts can be set Remote access to MySQL database What would be the best solution for me? Is there one?

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• Bios Memory settings and Virtualization + Ubuntu (Unofficial Answers Welcome) [closed]

  - by TardisGuy

  Attempting to optimize my (Main Windowless) Ubuntu system for my uses I will detail questions below, I understand this might be the wrong place to ask these questions. If so, my apologies and I thank you so much for your patience. Thanks to all the volenteers that have helped me learn ubuntu over the years (Since 5.10) This is a "short" list of questions I have been trying to figure out for some time. If you feel you can answer one but not another, that's already more than I could ask for. I have wrote this up in a format for easy navigation to important points Hopefully to less annoy your eyes. You're welcome :) or i'm sorry i annoy you. :( If you would be so kind, Please format answers as follows: question 1: _ _ _ _ _ or question 1-a: _ _ _ _ _ If you want to simply link me to relevant information, rather than type up something really detailed; that would be more than awesome! Memory Specific Questions Goal: Maximizing memory bandwith to better perform in Virtualization, and Large file compression. (Possible conflict?) Ganged vs Unganged "which is better?"** is relative, i know. But what about ganged vs unganged - With or without Bank/channel interleaving? a: Speculation - If i understand correctly, "channel interleaving has something to do with using both channels to read or write in a kind of "striping" pattern, as opposed to a standard half duplex operation.(probably wrong) but wouldn't ganged channels make this irrelevant? Memory Interleaving(bank). Does it have a down side? Does it require a ratio of clocks? (If I run 4x4gig ddr3) a. If im reading correctly(trying to learn), this is designed to spread operations between latency cycles to work around the higher latency of "normal" operation. b. However it seems to me that it has to be: divisible by fractions of a master clock? So if i run memory at 1333mhz, then the mean between 2 (physical) banks would operate every (roughly) 600Mhz? Warning! Possibly utter nonsense: (1333/2 interleaving to act like 1 memory module per 2 sticks of a total of 4 sticks, meaning 2x channels@4) c. which makes me wonder if there would be left over clock cycles the system would have to... "truncate/balance" or something? But I'm certain theres a feature somewhere i don't understand. Virtualization Questions AMD-V - Option of IOMMU Turned it on, why do i have extra option of "64MB"? If IOMMU is on, but "64MB" is "disabled", Is it on? (have scoured google, I still dont know) a. I think i understand that its supposed to (kind of) "set aside" a part of ram to act as a faster interactive zone for "stuff" (usb, Graphics, and... what?) b. I am using Nvidia graphics on AMD (Used kernel option "iommu=pt iommu=1, pt "passthrough"? No idea what they do, found it on google to solve boot up issue) c. Will this option help me use low latency sound hardware, like my midi keyboard? Can you recommend any additional tweaks? a. sysctl settings? b. swap settings? Grats, youve reached the end. Thanks for Reading.

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• XNA 2D Board game - trouble with the cursor

  - by Adorjan

  I just have started making a simple 2D board game using XNA, but I got stuck at the movement of the cursor. This is my problem: I have a 10x10 table on with I should use a cursor to navigate. I simply made that table with the spriteBatch.Draw() function because I couldn't do it on another way. So here is what I did with the cursor: public override void LoadContent() { ... mutato.Position = new Vector2(X, Y); //X=103, Y=107; mutato.Sebesseg = 45; ... mutato.Initialize(content.Load<Texture2D>("cursor"),mutato.Position,mutato.Sebesseg); ... } public override void HandleInput(InputState input) { if (input == null) throw new ArgumentNullException("input"); // Look up inputs for the active player profile. int playerIndex = (int)ControllingPlayer.Value; KeyboardState keyboardState = input.CurrentKeyboardStates[playerIndex]; if (input.IsPauseGame(ControllingPlayer) || gamePadDisconnected) { ScreenManager.AddScreen(new PauseMenuScreen(), ControllingPlayer); } else { // Otherwise move the player position. if (keyboardState.IsKeyDown(Keys.Down)) { Y = (int)mutato.Position.Y + mutato.Move; } if (keyboardState.IsKeyDown(Keys.Up)) { Y = (int)mutato.Position.Y - mutato.Move; } if (keyboardState.IsKeyDown(Keys.Left)) { X = (int)mutato.Position.X - mutato.Move; } if (keyboardState.IsKeyDown(Keys.Right)) { X = (int)mutato.Position.X + mutato.Move; } } } public override void Draw(GameTime gameTime) { mutato.Draw(spriteBatch); } Here's the cursor's (mutato) class: using System; using System.Collections.Generic; using System.Linq; using System.Text; using Microsoft.Xna.Framework; using Microsoft.Xna.Framework.Graphics; namespace Battleship.Components { class Cursor { public Texture2D Cursortexture; public Vector2 Position; public int Move; public void Initialize(Texture2D texture, Vector2 position,int move) { Cursortexture = texture; Position = position; Move = move; } public void Update() { } public void Draw(SpriteBatch spriteBatch) { spriteBatch.Draw(Cursortexture, Position, Color.White); } } } And here is a part of the InputState class where I think I should change something: public bool IsNewKeyPress(Keys key, PlayerIndex? controllingPlayer, out PlayerIndex playerIndex) { if (controllingPlayer.HasValue) { // Read input from the specified player. playerIndex = controllingPlayer.Value; int i = (int)playerIndex; return (CurrentKeyboardStates[i].IsKeyDown(key) && LastKeyboardStates[i].IsKeyUp(key)); } } If I leave the movement operation like this it doesn't have any sense: X = (int)mutato.Position.X - mutato.Move; However if I modify it to this: X = (int)mutato.Position.X--; it moves smoothly. Instead of this I need to move the cursor by fields (45 pixels), but I don't have any idea how to manage it.

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

  - by Jefffrey

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

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• Drawing random smooth lines contained in a square [migrated]

  - by Doug Mercer

  I'm trying to write a matlab function that creates random, smooth trajectories in a square of finite side length. Here is my current attempt at such a procedure: function [] = drawroutes( SideLength, v, t) %DRAWROUTES Summary of this function goes here % Detailed explanation goes here %Some parameters intended to help help keep the particles in the box RandAccel=.01; ConservAccel=0; speedlimit=.1; G=10^(-8); % %Initialize Matrices Ax=zeros(v,10*t); Ay=Ax; vx=Ax; vy=Ax; x=Ax; y=Ax; sx=zeros(v,1); sy=zeros(v,1); % %Define initial position in square x(:,1)=SideLength*.15*ones(v,1)+(SideLength*.7)*rand(v,1); y(:,1)=SideLength*.15*ones(v,1)+(SideLength*.7)*rand(v,1); % for i=2:10*t %Measure minimum particle distance component wise from boundary %for each vehicle BorderGravX=[abs(SideLength*ones(v,1)-x(:,i-1)),abs(x(:,i-1))]'; BorderGravY=[abs(SideLength*ones(v,1)-y(:,i-1)),abs(y(:,i-1))]'; rx=min(BorderGravX)'; ry=min(BorderGravY)'; % %Set the sign of the repulsive force for k=1:v if x(k,i)<.5*SideLength sx(k)=1; else sx(k)=-1; end if y(k,i)<.5*SideLength sy(k)=1; else sy(k)=-1; end end % %Calculate Acceleration w/ random "nudge" and repulive force Ax(:,i)=ConservAccel*Ax(:,i-1)+RandAccel*(rand(v,1)-.5*ones(v,1))+sx*G./rx.^2; Ay(:,i)=ConservAccel*Ay(:,i-1)+RandAccel*(rand(v,1)-.5*ones(v,1))+sy*G./ry.^2; % %Ad hoc method of trying to slow down particles from jumping outside of %feasible region for h=1:v if abs(vx(h,i-1)+Ax(h,i))<speedlimit vx(h,i)=vx(h,i-1)+Ax(h,i); elseif (vx(h,i-1)+Ax(h,i))<-speedlimit vx(h,i)=-speedlimit; else vx(h,i)=speedlimit; end end for h=1:v if abs(vy(h,i-1)+Ay(h,i))<speedlimit vy(h,i)=vy(h,i-1)+Ay(h,i); elseif (vy(h,i-1)+Ay(h,i))<-speedlimit vy(h,i)=-speedlimit; else vy(h,i)=speedlimit; end end % %Update position x(:,i)=x(:,i-1)+(vx(:,i-1)+vx(:,i))/2; y(:,i)=y(:,i-1)+(vy(:,i-1)+vy(:,1))/2; % end %Plot position clf; hold on; axis([-100,SideLength+100,-100,SideLength+100]); cc=hsv(v); for j=1:v plot(x(j,1),y(j,1),'ko') plot(x(j,:),y(j,:),'color',cc(j,:)) end hold off; % end My original plan was to place particles within a square, and move them around by allowing their acceleration in the x and y direction to be governed by a uniformly distributed random variable. To keep the particles within the square, I tried to create a repulsive force that would push the particles away from the boundaries of the square. In practice, the particles tend to leave the desired "feasible" region after a relatively small number of time steps (say, 1000)." I'd love to hear your suggestions on either modifying my existing code or considering the problem from another perspective. When reading the code, please don't feel the need to get hung up on any of the ad hoc parameters at the very beginning of the script. They seem to help, but I don't believe any beside the "G" constant should truly be necessary to make this system work. Here is an example of the current output: Many of the vehicles have found their way outside of the desired square region, [0,400] X [0,400].

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• AABB vs OBB Collision Resolution jitter on corners

  - by patt4179

  I've implemented a collision library for a character who is an AABB and am resolving collisions between AABB vs AABB and AABB vs OBB. I wanted slopes for certain sections, so I've toyed around with using several OBBs to make one, and it's working great except for one glaring issue; The collision resolution on the corner of an OBB makes the player's AABB jitter up and down constantly. I've tried a few things I've thought of, but I just can't wrap my head around what's going on exactly. Here's a video of what's happening as well as my code: Here's the function to get the collision resolution (I'm likely not doing this the right way, so this may be where the issue lies): public Vector2 GetCollisionResolveAmount(RectangleCollisionObject resolvedObject, OrientedRectangleCollisionObject b) { Vector2 overlap = Vector2.Zero; LineSegment edge = GetOrientedRectangleEdge(b, 0); if (!SeparatingAxisForRectangle(edge, resolvedObject)) { LineSegment rEdgeA = new LineSegment(), rEdgeB = new LineSegment(); Range axisRange = new Range(), rEdgeARange = new Range(), rEdgeBRange = new Range(), rProjection = new Range(); Vector2 n = edge.PointA - edge.PointB; rEdgeA.PointA = RectangleCorner(resolvedObject, 0); rEdgeA.PointB = RectangleCorner(resolvedObject, 1); rEdgeB.PointA = RectangleCorner(resolvedObject, 2); rEdgeB.PointB = RectangleCorner(resolvedObject, 3); rEdgeARange = ProjectLineSegment(rEdgeA, n); rEdgeBRange = ProjectLineSegment(rEdgeB, n); rProjection = GetRangeHull(rEdgeARange, rEdgeBRange); axisRange = ProjectLineSegment(edge, n); float axisMid = (axisRange.Maximum + axisRange.Minimum) / 2; float projectionMid = (rProjection.Maximum + rProjection.Minimum) / 2; if (projectionMid > axisMid) { overlap.X = axisRange.Maximum - rProjection.Minimum; } else { overlap.X = rProjection.Maximum - axisRange.Minimum; overlap.X = -overlap.X; } } edge = GetOrientedRectangleEdge(b, 1); if (!SeparatingAxisForRectangle(edge, resolvedObject)) { LineSegment rEdgeA = new LineSegment(), rEdgeB = new LineSegment(); Range axisRange = new Range(), rEdgeARange = new Range(), rEdgeBRange = new Range(), rProjection = new Range(); Vector2 n = edge.PointA - edge.PointB; rEdgeA.PointA = RectangleCorner(resolvedObject, 0); rEdgeA.PointB = RectangleCorner(resolvedObject, 1); rEdgeB.PointA = RectangleCorner(resolvedObject, 2); rEdgeB.PointB = RectangleCorner(resolvedObject, 3); rEdgeARange = ProjectLineSegment(rEdgeA, n); rEdgeBRange = ProjectLineSegment(rEdgeB, n); rProjection = GetRangeHull(rEdgeARange, rEdgeBRange); axisRange = ProjectLineSegment(edge, n); float axisMid = (axisRange.Maximum + axisRange.Minimum) / 2; float projectionMid = (rProjection.Maximum + rProjection.Minimum) / 2; if (projectionMid > axisMid) { overlap.Y = axisRange.Maximum - rProjection.Minimum; overlap.Y = -overlap.Y; } else { overlap.Y = rProjection.Maximum - axisRange.Minimum; } } return overlap; } And here is what I'm doing to resolve it right now: if (collisionDetection.OrientedRectangleAndRectangleCollide(obb, player.PlayerCollision)) { var resolveAmount = collisionDetection.GetCollisionResolveAmount(player.PlayerCollision, obb); if (Math.Abs(resolveAmount.Y) < Math.Abs(resolveAmount.X)) { var roundedAmount = (float)Math.Floor(resolveAmount.Y); player.PlayerCollision._position.Y -= roundedAmount; } else if (Math.Abs(resolveAmount.Y) <= 30.0f) //Catch cases where the player should be able to step over the top of something { var roundedAmount = (float)Math.Floor(resolveAmount.Y); player.PlayerCollision._position.Y -= roundedAmount; } else { var roundedAmount = (float)Math.Floor(resolveAmount.X); player.PlayerCollision._position.X -= roundedAmount; } } Can anyone see what might be the issue here, or has anyone experienced this before that knows a possible solution? I've tried for a few days to figure this out on my own, but I'm just stumped.

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• Some PowerShell goodness

  - by KyleBurns

  Ever work somewhere where processes dump files into folders to maintain an archive?  Me too and Windows Explorer hates it.  Very often I find myself needing to organize these files into subfolders so that I can go after files without locking up Windows Explorer and my answer used to be to write a program in something like C# to do the job.  These programs will typically enumerate the files in a folder and move each file to a subdirectory named based on a datestamp.  The last such program I wrote had to use lower-level Win32 API calls to perform the enumeration because it appears the standard .Net calls make use of the same method of enumerating the directories that Windows Explorer chokes on when dealing with a large number of entries in a particular directory, so a simple task was accomplished with a lot of code. Of course, this little utility was just something I used to make my life easier and "not a production app", so it was in my local source folder and not source control when my hard drive died.  So... I was getting ready to re-create it and thought it might be a good idea to play with PowerShell a bit - something I had been wanting to do but had not yet met a requirement to make me do it.  The resulting script was amazingly succinct and even building the flexibility for parameterization and adding line breaks for readability was only about 25 lines long.  Here's the code with discussion following: param(     [Parameter(         Mandatory = $false,         Position = 0,         HelpMessage = "Root of the folders or share to archive.  Be sure to end with appropriate path separator"     )]     [String] $folderRoot="\\fileServer\pathToFolderWithLotsOfFiles\",       [Parameter(         Mandatory = $false,         Position = 1     )]     [int] $days = 1 ) dir $folderRoot|?{(!($_.PsIsContainer)) -and ((get-date) - $_.lastwritetime).totaldays -gt $days }|%{     [string]$year=$([string]$_.lastwritetime.year)     [string]$month=$_.lastwritetime.month     [string]$day=$_.lastwritetime.day     $dir=$folderRoot+$year+"\"+$month+"\"+$day     if(!(test-path $dir)){         new-item -type container $dir     }     Write-output $_     move-item $_.fullname $dir } The script starts by declaring two parameters.  The first parameter holds the path to the folder that I am going to be sorting into subdirectories.  The path separator is intended to be included in this argument because I didn't want to mess with determining whether this was local or UNC and picking the right separator in code, but this could be easily improved upon using Path.Combine since PowerShell has access to the full framework libraries.  The second parameter holds a minimum age in days for files to be removed from the root folder.  The script then pipes the dir command through a query to include only files (by excluding containers) and of those, only entries that meet the age requirement based on the last modified datestamp.  For each of those, the datestamp is used to construct a folder name in the format YYYY\MM\DD (if you're in an environment where even a day's worth of files need further divided, you could make this more granular) and the folder is created if it does not yet exist.  Finally, the file is moved into the directory. One of the things that was really cool about using PowerShell for this task is that the new-item command is smart enough to create the entire subdirectory structure with a single call.  In previous code that I have written to do this kind of thing, I would have to test the entire tree leading down to the subfolder I want, leading to a lot of branching code that detracted from being able to quickly look at the code and understand the job it performs. Overall, I have to say I'm really pleased with what has been done making PowerShell powerful and useful.

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• How do you deal with poor management [closed]

  - by Sybiam

  I come from a company where during a project, we saw the client 3 time during the whole project. We were never informed when did the client came in office in order to discuss with him about his requirements. I did setup redmine and told them that if they have any request they can post an issue there. But they never really used redmine to publish anything. They would instead: harass a team member on the phone at any time of the day or night hand us over sheets of paper with new requests or changes hand us over new design (graphical) They requested how much time it would take us to finish the project, I gave them a date and a week to test everything and deployment. I calculated that time taking into account the current features we had to do. And then blamed us that our deadline was wrong and that we lied. But the truth is that one week before that deadline they added a couple of monster feature from nowhere and that week were we were supposed to test and deploy, my friends spent all day in the office changing all little things. After that project, my friend got some kind of depression and got scared everytime his phone rang. They kind of used him as a communication proxy. After that project of hell, (every body got pissed off on that project) as far as I know the designer who was working with us left work after that project and she had some kind of issue too with managers. My team also started looking for work somewhere else. At first I tried to get things straight with management, I tried to make a meeting to discuss about the communication issues and so on.. What really pissed me off and made me leave that job for good is the following. Me: "We have to discuss about what went wrong on the last project. It's quite important" Him: "Lets talk about it in a week or two. Just make a list of all the things you did wrong" Me: "We already have a new project and we want to prevent what happened on the last project to happen again" Him: "Just do it and well have our meeting in a week, make a list of all the thing you did wrong." It kind of ended there then he organized a meeting at a moment I wasn't unable to come. My friend discussed with him and tried to explained him that we really had to discuss about organization issue on how to manage a project. And his answer was pretty much: "During the meeting I don't want to ear how you want to us to manage a project but I want to know what you guys did wrong" After that I felt it wasn't even worth it discussing anything since they weren't even ready listening to us. Found a new job and I'm pretty happy with my choice. I'd like to know how you'd handle such situation. Is there anything to do to solve communication problem? After that project my friend got a depression and some other employee had their down too as far as I know. I wonder what else we can do other than leave these place as soon as possible. Feel sad for the people that are still there and get screamed at just because they need money in order to eat and finding an other job like that isn't that easy. note I died a little when our boss asked us to make a list of things we (programmers) did wrong. This is probably the stupidest request I ever got. If everybody thinks they did everything right, it doesn't mean that there is no problems. Individual problem are rarely the big issue. Colleagues help each others and solve theses issues to prevent problems.

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• Class design issue

  - by user2865206

  I'm new to OOP and a lot of times I become stumped in situations similar to this example: Task: Generate an XML document that contains information about a person. Assume the information is readily available in a database. Here is an example of the structure: <Person> <Name>John Doe</Name> <Age>21</Age> <Address> <Street>100 Main St.</Street> <City>Sylvania</City> <State>OH</State> </Address> <Relatives> <Parents> <Mother> <Name>Jane Doe</Name> </Mother> <Father> <Name>John Doe Sr.</Name> </Father> </Parents> <Siblings> <Brother> <Name>Jeff Doe</Name> </Brother> <Brother> <Name>Steven Doe</Name> </Brother> </Siblings> </Relatives> </Person> Ok lets create a class for each tag (ie: Person, Name, Age, Address) Lets assume each class is only responsible for itself and the elements directly contained Each class will know (have defined by default) the classes that are directly contained within them Each class will have a process() function that will add itself and its childeren to the XML document we are creating When a child is drawn, as in the previous line, we will have them call process() as well Now we are in a recursive loop where each object draws their childeren until all are drawn But what if only some of the tags need to be drawn, and the rest are optional? Some are optional based on if the data exists (if we have it, we must draw it), and some are optional based on the preferences of the user generating the document How do we make sure each object has the data it needs to draw itself and it's childeren? We can pass down a massive array through every object, but that seems shitty doesnt it? We could have each object query the database for it, but thats a lot of queries, and how does it know what it's query is? What if we want to get rid of a tag later? There is no way to reference them. I've been thinking about this for 20 hours now. I feel like I am misunderstanding a design principle or am just approaching this all wrong. How would you go about programming something like this? I suppose this problem could apply to any senario where there are classes that create other classes, but the classes created need information to run. How do I get the information to them in a way that doesn't seem fucky? Thanks for all of your time, this has been kicking my ass.

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• When things go awry

  - by Phil Factor

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

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