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• Hyper-V Live Migration across Sites!

  - by Ryan Roussel

  One of the great sessions I sat in on at Tech Ed this week was stretching a Windows 2008 R2 Hyper-V  Failover Cluster across sites.  With this ability, you could actually implement a Hyper-V cluster where you could migrate or even Live Migrate VMs across sites.   With this area’s propensity for Hurricanes, this will be a very popular topic for me over the next few months. While this technology is possible today, it’s also very complicated and can be very expensive to implement.    First your WAN connection has to support the ability to trunk your VLAN across both sites in order to Live Migrate.  This means you can’t use a Layer 3 routed connection like MPLS.  It has to be a Metro Ethernet connection or "Dark Fiber”.  Dark Fiber is unused Fiber already in the ground that can be leased from  various providers. Both of these connections would allow you to trunk layer 2 across your WAN.  Cisco does have the ability to trunk layer 2 across a routed connection by muxing the traffic but this is only available in their Nexus product line which has a very steep price tag.   If you are stuck with MPLS or the like and Nexus switching is not a realistic possibility, you will have to implement a multi-subnet cluster in which case Live Migration won’t be possible.  However you can still failover VMs to the remote site with some planning and manual intervention.  The consideration here is that the VMs will be on a different subnet once migrated, so you will have to change the IP addressing of your VMs.  This also has ramifications with DNS and Name resolution to control your down time.  DHCP with Reservations for your VMs is the preferred method to achieve the IP changes as this will automate that part of the process.   Secondly, you will have to have  a mechanism to replicate your storage across both sites.  Many SAN vendors natively support hardware based synchronous and asynchronous replication.  Some even support cluster shared volumes which were introduced in 2008 R2.   If your SANs do not support this natively, there are alternative file based replication products either software based like Double Take or hardware appliance like EMC.  Be sure to check with your vendor on the support of Disk majority if you’re replicating your quorum disk between SANs.   The last consideration is the ability to maintain quorum for your cluster.  If your replication provider does not support Disk Majority through replication, you will have to explore Node Majority with File Share Witness.  This will affect your design as a 3 node cluster with 1 node at the remote site and FSW at the production site would not have the ability to maintain quorum if the production site was lost. MS best practice for this would be to implement an even node cluster with 2 nodes at  each site and the FSW at a third site.   And there you have it.  While some considerations and research goes into implementing this solution, even a multi-subnet solution would be invaluable to organizations in the implementations of “warm” DR sites.

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• C# Open Source software that is useful for learning Design Patterns

  - by Fathom Savvy

  In college I took a class in Expert Systems. The language the book taught (CLIPS) was esoteric - Expert Systems: Principles and Programming, Fourth Edition. I remember having a tough time with it. So, after almost failing the class, I needed to create the most awesome Expert System for my final presentation. I chose to create an expert system that would calculate risk analysis for a person's retirement portfolio. In short, the system would provide the services normally performed by one's financial adviser. In other words, based on personality, age, state of the macro economy, and other factors, should one's portfolio be conservative, moderate, or aggressive? In the appendix of the book (or on the CD-ROM), there was this in-depth example program for something unrelated to my presentation. Over my break, I read and re-read every line of that program until I understood it to the letter. Even though it was unrelated, I learned more than I ever could by reading all of the chapters. My presentation turned out to be pretty damn good and I received praises from my professor and classmates. So, the moral of the story is..., by understanding other people's code, you can gain greater insight into a language/paradigm than by reading canonical examples. Still, to this day, I am having trouble with everyday design patterns such as the Factory Pattern. I would like to know if anyone could recommend open source software that would help me understand the Gang of Four design patterns, at the very least. I have read the books, but I'm having trouble writing code for the concepts in the real world. Perhaps, by studying code used in today's real world applications, it might just "click". I realize a piece of software may only implement one kind of design pattern. But, if the pattern is an implementation you think is good for learning, and you know what pattern to look for within the source, I'm hoping you can tell me about it. For example, the System.Linq.Expressions namespace has a good example of the Visitor Pattern. The client calls Expression.Accept(new ExpressionVisitor()), which calls ExpressionVisitor (VisitExtension), which calls back to Expression (VisitChildren), which then calls Expression (Accept) again - wooah, kinda convoluted. The point to note here is that VisitChildren is a virtual method. Both Expression and those classes derived from Expression can implement the VisitChildren method any way they want. This means that one type of Expression can run code that is completely different from another type of derived Expression, even though the ExpressionVisitor class is the same in the Accept method. (As a side note Expression.Accept is also virtual). In the end, the code provides a real world example that you won't get in any book because it's kinda confusing. To summarize, If you know of any open source software that uses a design pattern implementation you were impressed by, please list it here. I'm sure it will help many others besides just me. public class VisitorPatternTest { public void Main() { Expression normalExpr = new Expression(); normalExpr.Accept(new ExpressionVisitor()); Expression binExpr = new BinaryExpression(); binExpr.Accept(new ExpressionVisitor()); } } public class Expression { protected internal virtual Expression Accept(ExpressionVisitor visitor) { return visitor.VisitExtension(this); } protected internal virtual Expression VisitChildren(ExpressionVisitor visitor) { if (!this.CanReduce) { throw Error.MustBeReducible(); } return visitor.Visit(this.ReduceAndCheck()); } public virtual Expression Visit(Expression node) { if (node != null) { return node.Accept(this); } return null; } public Expression ReduceAndCheck() { if (!this.CanReduce) { throw Error.MustBeReducible(); } Expression expression = this.Reduce(); if ((expression == null) || (expression == this)) { throw Error.MustReduceToDifferent(); } if (!TypeUtils.AreReferenceAssignable(this.Type, expression.Type)) { throw Error.ReducedNotCompatible(); } return expression; } } public class BinaryExpression : Expression { protected internal override Expression Accept(ExpressionVisitor visitor) { return visitor.VisitBinary(this); } protected internal override Expression VisitChildren(ExpressionVisitor visitor) { return CreateDummyExpression(); } protected internal Expression CreateDummyExpression() { Expression dummy = new Expression(); return dummy; } } public class ExpressionVisitor { public virtual Expression Visit(Expression node) { if (node != null) { return node.Accept(this); } return null; } protected internal virtual Expression VisitExtension(Expression node) { return node.VisitChildren(this); } protected internal virtual Expression VisitBinary(BinaryExpression node) { return ValidateBinary(node, node.Update(this.Visit(node.Left), this.VisitAndConvert<LambdaExpression>(node.Conversion, "VisitBinary"), this.Visit(node.Right))); } }

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• Speakers, Please Check Your Time

  - by AjarnMark

  Woodrow Wilson was once asked how long it would take him to prepare for a 10 minute speech. He replied "Two weeks". He was then asked how long it would take for a 1 hour speech. "One week", he replied. 2 hour speech? "I'm ready right now," he replied.  Whether that is a true story or an urban legend, I don’t really know, but either way, it is a poignant reminder for all speakers, and particularly apropos this week leading up to the PASS Community Summit. (Cross-posted to the PASS Professional Development Virtual Chapter blog #PASSProfDev.) What’s the point of that story?  Simply this…if you have plenty of time to do your presentation, you don’t need to prepare much because it is easy to throw in more and more material to stretch out to your allotted time.  But if you are on a tight time constraint, then it will take significant preparation to distill your talk down to only the essential points. I have attended seven of the last eight North American Summit events, and every one of them has been fantastic.  The speakers are great, the material is timely and relevant, and the networking opportunities are awesome.  And every year, there is one little thing that just bugs me…speakers going over their allotted time.  Why does it bother me so?  Well, if you look at a typical schedule for a Summit, you’ll see that there are six or more sessions going on at the same time, and only 15 minutes to move from one to another.  If you’re trying to maximize your training dollar by attending something during every session time slot, and you don’t want to be the last guy trying to squeeze into the middle of the row, then those 15 minutes can be critical.  All the more so if you need to stop and use the bathroom or if you have to hike to the opposite end of the convention center.  It is really a bad position to find yourself having to choose between learning the last key points of Speaker A who is going over time, and getting over to Speaker B on time so you don’t miss her key opening remarks. And frankly, I think it is just rude.  Yes, the speakers are the function, after all they are bringing the content that the rest of us are paying to learn.  But it is also an honor to be given the opportunity to speak at a conference like this, and no one speaker is so important that the conference would be a disaster without him.  Speakers know when they submit their abstract, long before the conference, how much time they will have.  It has been the same pattern at the Summit for at least the last eight years.  Program Sessions are 75 minutes long.  Some speakers who have a good track record, and meet other qualifying criteria, are extended an invitation to present a Spotlight Session which is 90 minutes (a 20% increase).  So there really is no excuse.  It’s not like you were promised a 2-hour segment and then discovered when you got here that it was only 75 minutes.  In fact, it’s not like PASS advertised 90-minute sessions for everyone and then a select few were cut back to only 75.  As a speaker, you know well before you get here which type of session you are doing and how long it is, so as a professional, you should plan accordingly. Now you might think that this only happens to rookies, but I’ll tell you that some of the worst offenders are big-name veterans who draw huge attendance numbers for their sessions.  Some attendees blow this off as, “Hey, it’s so-and-so, and I’d stay here for hours and listen to him/her talk.”  To which I would reply, “Then they should have submitted for a pre- or post-conference day-long seminar instead, but don’t try to squeeze your day-long talk into a 90-minute session.”  Now I don’t really believe that these speakers are being malicious or just selfishly trying to extend their time in the spotlight.  I think that most of them are merely being undisciplined and did not trim their presentation sufficiently, or allowed themselves to get off-track (often in a generous attempt to help someone in the audience with a question or problem that really should have been noted for further discussion after the session). So here is my recommendation…my plea, even.  TRIM THE FAT!  Now.  Before it’s too late.  Before you even get on the airplane, take a long, hard look at your presentation and eliminate some of the points that you originally thought you had to make, but in reality are not truly crucial to your main topic.  Delete a few slides.  Test your demos and have them already scripted rather than typing them during your talk.  It is better to cut out too much and end up with plenty of time at the end for Questions & Answers.  And you can always keep some notes on the stuff that you cut out so that you could fill it back in at the end as bonus material if you really do end up with a whole bunch of time on your hands.  But I don’t think you will.  And if you do, that will look even better to the audience as it will look like you’re giving them something extra that not every audience gets.  And they will thank you for that.

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• Why won't my code work in Ubuntu Server 11.10? Is it because of gd library?

  - by Derrick

  I get this error when running the following code: No such file found at "widgets/104-text.png" I know that the code works because it works on my other non-ubuntu server. I do not know if it is gd library or what. I tried both the bundled version and the non-bundled and both do not make this code work. $con = mysql_connect("localhost","user","abc123"); if (!$con) { die('Could not connect: ' . mysql_error()); } mysql_select_db("satabase_name", $con); $productid2 = $this->product->id; $thename = mysql_query("SELECT * FROM pshop_product_lang WHERE id_product = '$productid2' LIMIT 1"); $thename2 = mysql_fetch_array($thename); $string2 = $thename2['name']; $string = (strlen($string2) > 25) ? substr($string2, 0, 25) . '...' : $string2; $font = 4; $width = imagefontwidth($font) * strlen($string); $height = imagefontheight($font); $image = imagecreatetruecolor ($width,$height); $white = imagecolorallocate ($image,255,255,255); $black = imagecolorallocate ($image,0,0,0); imagefill($image,0,0,$white); imagestring($image,$font,0,0,$string, $black); imagepng($image, 'widgets/' . $productid2 . '-text.png'); $getimg110 = mysql_query("SELECT * FROM pshop_image WHERE id_product = '$productid2'"); $gotimg110 = mysql_fetch_array($getimg110); $slash110 = addcslashes($gotimg110[id_image], '\0..\999999999999999999999'); $str110 = str_replace('\\', '/', $slash110); $newimg110 = '<img src="img/p' . $str110 . '/' . $gotimg110[id_image] . '-large_default.jpg" />'; include("conf.inc.php"); include('ImageWorkshop.php'); // Initialization of layer you need $pinguLayer = new ImageWorkshop(array( 'imageFromPath' => 'widgets/background.png', )); $pinguLayer2 = new ImageWorkshop(array( 'imageFromPath' => 'img/p' . $str110 . '/' . $gotimg110[id_image] . '-large_default.jpg', )); $pinguLayer3 = new ImageWorkshop(array( 'imageFromPath' => 'widgets/' . $productid2 . '-text.png', )); // resize pingu layer $thumbWidth2 = 150; // px $thumbHeight2 = 150; $thumbWidth = 400; // px $thumbHeight = 200; $pinguLayer2->resizeInPixel($thumbWidth2, $thumbHeight2); $pinguLayer->resizeInPixel($thumbWidth, $thumbHeight); // Add 2 layers on pingu layer $pinguLayer->addLayerOnTop($pinguLayer2, null, null, 'LM'); $pinguLayer->addLayerOnTop($pinguLayer3, 70, 25, 'MM'); // Saving the result in a folder $pinguLayer->save("widgets/", $productid2 . ".gif", true, null, 95); The file path is correct, however this part of the code is not creating the image as it is supposed to: $thename2 = mysql_fetch_array($thename); $string2 = $thename2['name']; $string = (strlen($string2) > 25) ? substr($string2, 0, 25) . '...' : $string2; $font = 4; $width = imagefontwidth($font) * strlen($string); $height = imagefontheight($font); $image = imagecreatetruecolor ($width,$height); $white = imagecolorallocate ($image,255,255,255); $black = imagecolorallocate ($image,0,0,0); imagefill($image,0,0,$white); imagestring($image,$font,0,0,$string, $black); imagepng($image, 'widgets/' . $productid2 . '-text.png');

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• How can I have multiple layers in my map array?

  - by Manl400

  How do I load Levels in my game, as in Layer 1 would be Objects, Layer 2 would be Characters and so on. I only need 3 layers, and they will all be put on top of each other. i.e having a flower with a transparent background to be put on grass or dirt on the layer below.I would like to Read From the same file too. How would i go about doing this? Any help would be appreciated. I load the map from a level file which are just numbers corresponding to a tile in the tilesheet. Here is the level file [Layer1] 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 [Layer2] 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 [Layer3] 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 And here is the code that interprets it void LoadMap(const char *filename, std::vector< std::vector <int> > &map) { std::ifstream openfile(filename); if(openfile.is_open()) { std::string line, value; int space; while(!openfile.eof()) { std::getline(openfile, line); if(line.find("[TileSet]") != std::string::npos) { state = TileSet; continue; } else if (line.find("[Layer1]") != std::string::npos) { state = Map; continue; } switch(state) { case TileSet: if(line.length() > 0) tileSet = al_load_bitmap(line.c_str()); break; case Map: std::stringstream str(line); std::vector<int> tempVector; while(!str.eof()) { std::getline(str, value, ' '); if(value.length() > 0) tempVector.push_back(atoi(value.c_str())); } map.push_back(tempVector); break; } } } else { } } and this is how it draws the map. Also the tile sheet is 1280 by 1280 and the tilesizeX and tilesizeY is 64 void DrawMap(std::vector <std::vector <int> > map) { int mapRowCount = map.size(); for(int i, j = 0; i < mapRowCount; i ++) { int mapColCount = map[i].size(); for (int j = 0; j < mapColCount; ++j) { int tilesetIndex = map[i][j]; int tilesetRow = floor(tilesetIndex / TILESET_COLCOUNT); int tilesetCol = tilesetIndex % TILESET_COLCOUNT; al_draw_bitmap_region(tileSet, tilesetCol * TileSizeX, tilesetRow * TileSizeY, TileSizeX, TileSizeY, j * TileSizeX, i * TileSizeX, NULL); } } } EDIT: http://i.imgur.com/Ygu0zRE.jpg

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• Using NSpec at various architectural layers

  - by nono

  Having read the quick start at nspec.org, I realized that NSpec might be a useful tool in a scenario which was becoming a bit cumbersome with NUnit alone. I'm adding an OAuth (or, DotNetOpenAuth) to a website and quickly made a mess of writing test methods such as [Test] public void UserIsLoggedInLocallyPriorToInvokingExternalLoginAndExternalLoginSucceedsAndExternalProviderIdIsNotAlreadyAssociatedWithUserAccount() { ... } ... and I wound up with maybe a dozen permutations of this theme, for the user already being logged in locally and not locally, the external login succeeding or failing, etc. Not only were the method names unwieldy, but every test needed a setup that contained parts in common with a different set of other tests. I realized that NSpec's incremental setup capabilities would work great for this, and for a while I was trucking a long wonderfully, with code like act = () => { actionResult = controller.ExternalLoginCallback(returnUrl); }; context["The user is already logged in"] = () => { before = () => identity.Setup(x => x.IsAuthenticated).Returns(true); context["The external login succeeds"] = () => { before = () => oauth.Setup(x => x.VerifyAuthentication(It.IsAny<string>())).Returns(new AuthenticationResult(true, providerName, "provideruserid", "username", new Dictionary<string, string>())); context["External login already exists for current user"] = () => { before = () => authService.Setup(x => x.ExternalLoginExistsForUser(It.IsAny<string>(), It.IsAny<string>(), It.IsAny<string>())).Returns(true); it["Should add 'login sucessful' alert"] = () => { var alerts = (IList<Alert>)controller.TempData[TempDataKeys.AlertCollection]; alerts[0].Message.should_be_same("Login successful"); alerts[0].AlertType.should_be(AlertType.Success); }; it["Should return a redirect result"] = () => actionResult.should_cast_to<RedirectToRouteResult>(); }; context["External login already exists for another user"] = () => { before = () => authService.Setup(x => x.ExternalLoginExistsForAnyOtherUser(It.IsAny<string>(), It.IsAny<string>(), It.IsAny<string>())).Returns(true); it["Adds an error alert"] = () => { var alerts = (IList<Alert>)controller.TempData[TempDataKeys.AlertCollection]; alerts[0].Message.should_be_same("The external login you requested is already associated with a different user account"); alerts[0].AlertType.should_be(AlertType.Error); }; it["Should return a redirect result"] = () => actionResult.should_cast_to<RedirectToRouteResult>(); }; This approach seemed to work magnificently until I prepared to write test code for my ApplicationServices layer, to which I delegate viewmodel manipulation from my MVC controllers, and which coordinates the operations of the lower data repository layer: public void CreateUserAccountFromExternalLogin(RegisterExternalLoginModel model) { throw new NotImplementedException(); } public void AssociateExternalLoginWithUser(string userName, string provider, string providerUserId) { throw new NotImplementedException(); } public string GetLocalUserName(string provider, string providerUserId) { throw new NotImplementedException(); } I have no idea what in the world to name the test class, the test methods, or even if I should perhaps include the testing for this layer into the test class from my large code snippet above, so that a single feature or user action could be tested without regard to architectural layering. I can't find any tutorials or blog posts which cover more than simple examples, so I would appreciate any recommendations or pointing in the right direction. I would even welcome "your question is invalid"-type answers as long as some explanation is provided.

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• DRY Validation with MVC2

  - by Matthew

  Hi All, I'm trying to figure out how I can define validation rules for my domain objects in one single location within my application but have run in to a snag... Some background: My location has several parts: - Database - DAL - Business Logic Layer - SOAP API Layer - MVC website The MVC website accesses the database via the SOAP API, just as third parties would. We are using server and and client side validation on the MVC website as well as in the SOAP API Layer. To avoid having to manually write client side validation we are implementing strongly typed views in conjunction with the Html.TextBoxFor and Html.ValidationMessageFor HTML helpers, as shown in Step 3 here. We also create custom models for each form where one form takes input for multiple domain objects. This is where the problem begins, the HTML helpers read from the model for the data annotation validation attributes. In most cases our forms deal with multiple domain objects and you can't specify more than one type in the <%@Page ... Inherits="System.Web.Mvc.ViewPage" % page directive. So we are forced to create a custom model class, which would mean duplicating validation attributes from the domain objects on to the model class. I've spent quite some time looking for workarounds to this, such has referencing the same MetadataType from both the domain class and the custom MVC models, but that won't work for several reasons: You can only specify one MetadataType attribute per class, so its a problem if a model references multiple domain objects, each with their own metadata type. The data annotation validation code throws an exception if the model class doesn't contain a property that is specified in the referenced MetadataType which is a problem with the model only deals with a subset of the properties for a given domain object. I've looked at other solutions as well but to no avail. If anyone has any ideas on how to achieve a single source for validation logic that would work across MVC client and server side validation functionality and other locations (such as my SOAP API) I would love to hear it! Thanks in advance, Matthew

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• Why does Adding Core Animation slow down drawing of my NSTableView?

  - by Will Goring

  I have a simple App that displays a list of items using NSTableView. There are usually about 15-25 items in the list, and the table has 10 columns, all but one of which are text (the other's an icon.) There are simple data transformers on a couple of the columns. So nothing taxing; you'd expect it to run just fine. And as it stands, it is; the app is responsive and everything draws pretty much instantly. Scrolling, changing column sizes, resizing the window; whatever you do the redraws keep up with the mouse-pointer. Tonight, I thought I'd try adding a little visual flair to the app with Core Animation (which I've never used before,) but I've found that if anything above the NSTableView in the hierarchy is set 'Wants Core Animation Layer,' then the NSTableView redraws go to hell. Scrolling is usually fine, but resizing columns or the window causes it to pick up an effect like texture tearing, where some of the rows have the new size, and some have the old one, and everything flickers horribly. It looks terrible. Basically it looks like what you'd expect if rendering the individual rows or columns was taking a long time. I've put it through Shark and, sure enough, it looks like it's spending most of its time drawing the text in the cells; what I don't understand is why that should take longer when there's a Core Animation layer involved than when there isn't - and quite noticeably longer at that. Has anyone got any ideas? Is there any Core Animation initialisation or config I've missed or something (I've literally just ticked the "Wants Core Animation Layer" box in IB)? Cheers, Will

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• little more help with a CATiledLayer

  - by Brodie4598

  Okay so I am trying to adapt an online tutorial for CATiledLayer to use in my app. The example uses a PDF but I need to display a JPG. I'm getting close, but I just cant figure this out. Should I be using a UIImage or something else? #import <QuartzCore/QuartzCore.h> #import "practiceViewController.h" @implementation practiceViewController - (void)viewDidLoad { [super viewDidLoad]; NSBundle *bundle = [[NSBundle mainBundle]autorelease]; NSString *path = [bundle pathForResource:@"H-5" ofType:@"jpg"]; NSData *data = [NSData dataWithContentsOfFile:path]; image = [UIImage imageWithData:data]; CGRect pageRect = CGRectMake(0, 0, 1600, 2400); CATiledLayer *tiledLayer = [CATiledLayer layer]; tiledLayer.delegate = self; tiledLayer.tileSize = CGSizeMake(1024.0, 1024.0); tiledLayer.levelsOfDetail = 1000; tiledLayer.levelsOfDetailBias = 1000; tiledLayer.frame = pageRect; myContentView = [[UIView alloc] initWithFrame:pageRect]; [myContentView.layer addSublayer:tiledLayer]; CGRect viewFrame = self.view.frame; viewFrame.origin = CGPointZero; UIScrollView *scrollView = [[UIScrollView alloc] initWithFrame:viewFrame]; scrollView.delegate = self; scrollView.contentSize = pageRect.size; scrollView.maximumZoomScale = 1000; [scrollView addSubview:myContentView]; [self.view addSubview:scrollView]; } - (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView { return myContentView; } - (void)drawLayer:(CALayer *)layer inContext:(CGContextRef)ctx { NEED HE:LP WITH THIS } @end

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• Explicit behavior with checks vs. implicit behavior

  - by Silviu

  I'm not sure how to construct the question but I'm interested to know what do you guys think of the following situations and which one would you prefer. We're working at a client-server application with winforms. And we have a control that has some fields automatically calculated upon filling another field. So we're having a field currency which when filled by the user would determine an automatic filling of another field, maybe more fields. When the user fills the currency field, a Currency object would be retrieved from a cache based on the string introduced by the user. If entered currency is not found in the cache a null reference is returned by the cache object. Further down when asking the application layer to compute the other fields based on the currency, given a null currency a null specific field would be returned. This way the default, implicit behavior is to clear all fields. Which is the expected behavior. What i would call the explicit implementation would be to verify that the Currency object is null in which case the depending fields are cleared explicitly. I think that the latter version is more clear, less error prone and more testable. But it implies a form of redundancy. The former version is not as clear and it implies a certain behavior from the application layer which is not expressed in the tests. Maybe in the lower layer tests but when the need arises to modify the lower layers, so that given a null currency something else should be returned, i don't think a test that says just that without a motivation is going to be an impediment for introducing a bug in upper layers. What do you guys think?

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• Service Oriented Architecture & Domain-Driven Design

  - by Michael

  I've always developed code in a SOA type of way. This year I've been trying to do more DDD but I keep getting the feeling that I'm not getting it. At work our systems are load balanced and designed not to have state. The architecture is: Website ===Physical Layer== Main Service ==Physical Layer== Server 1/Service 2/Service 3/Service 4 Only Server 1,Service 2,Service 3 and Service 4 can talk to the database and the Main Service calls the correct service based on products ordered. Every physical layer is load balanced too. Now when I develop a new service, I try to think DDD in that service even though it doesn't really feel like it fits. I use good DDD principles like entities, value types, repositories, aggregates, factories and etc. I've even tried using ORM's but they just don't seem like they fit in a stateless architecture. I know there are ways around it, for example use IStatelessSession instead of ISession with NHibernate. However, ORM just feel like they don't fit in a stateless architecture. I've noticed I really only use some of the concepts and patterns DDD has taught me but the overall architecture is still SOA. I am starting to think DDD doesn't fit in large systems but I do think some of the patterns and concepts do fit in large systems. Like I said, maybe I'm just not grasping DDD or maybe I'm over analyzing my designs? Maybe by using the patterns and concepts DDD has taught me I am using DDD? Not sure if there is really a question to this post but more of thoughts I've had when trying to figure out where DDD fits in overall systems and how scalable it truly is. The truth is, I don't think I really even know what DDD is?

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• Extract <name> attribute from KML

  - by Ozaki

  I am using OpenLayers for a mapping service. In which I have several KML layers that are using KML feeds from server to populate data on the map. It currently plots: images / points / vector lines & shapes. But on these points it will not add a label with the value of the for the placemark in the KML. What I have currently tried is: ////////////////////KML Feed for * Layer// var surveylinelayer = new OpenLayers.Layer.Vector("First KML Layer", { projection: new OpenLayers.Projection("EPSG:4326"), strategies: [new OpenLayers.Strategy.Fixed()], protocol: new OpenLayers.Protocol.HTTP({ url: firstKMLURL, format: new OpenLayers.Format.KML({ extractStyles: true, extractAttributes: true }) }), styleMap: new OpenLayers.StyleMap({ "default": KMLStyle }) }); then the Style as follows: var KMLStyle = new OpenLayers.Style({ //label: "${name}", // This method will display nothing fillOpacity: 1, pointRadius: 10, fontColor: "#7E3C1C", fontSize: "13px", fontFamily: "Courier New, monospace", fontWeight: "strong", labelXOffset: "0", labelYOffset: "-15" }, { //dynamic label context: { label: function(feature) { return "Feature Name: " + feature.attributes.name; // also displays nothing } } }); Example of the KML: <Placemark> <name>POI1</name> <Style> <LabelStyle> <color>ffffffff</color> </LabelStyle> </Style> <Point> <coordinates>0.000,0.000</coordinates> </Point> </Placemark> When debugging I just hit "feature is undefined" and am unsure why it would be undefined in this instance?

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• Java repaint is slow under certain conditions.

  - by Gabriel A. Zorrilla

  I'm doing a simple grid which each square is highlighted by the cursor: They are a couple of JPanels, mapgrid and overlay inside a JLayeredPane, with mapgrid on the bottom. Mapgrid just draws on initialization the grid, its paint metodh is: public void paintComponent(Graphics g) { super.paintComponent(g); Graphics2D g2d = (Graphics2D) g; g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); for (int i = 0; i < h; i++) { for (int j = 0; j < w; j++) { g2d.setColor(new Color(128, 128, 128, 255)); g2d.drawRect(tileSize * j, i * tileSize, tileSize, tileSize); } } In the overlay JPanel is where the highlighting occurs, this is what is repainted when the mouse is moved: public void paintComponent(Graphics g) { super.paintComponent(g); Graphics2D g2d = (Graphics2D) g; g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); g2d.setColor(new Color(255, 255, 128, 255)); g2d.drawRect((pointerX/tileSize)*tileSize,(pointerY/ tileSize)*tileSize, tileSize, tileSize); } I noticed that even though the base layer (mapgrid) is NOT repainted when the mouse moves, just the transparent overlay layer, the performance is lacking. If i give the overlay JPanel a background, its way faster. If i remove the mapgrid Antialiasing, its a bit faster too. I don't know why giving a background to the overlay layer (and thus, hiding the mapgrid) or disabling antialiasing in the mapgrid leads to much better performance. Is there a better way to do this? Why does this happen?

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• General N-Tier Architecture Question

  - by whatispunk

  In an N-Tier app you're supposed to have a business logic layer and a data access layer. Is it bad to simply have two assemblies: BusinessLogicLayer.dll and DataAccessLayer.dll to handle all this logic? How do you actually represent these layers. It seems silly, the way I've seen it, to have a BusinessLogic class library containing classes like: CustomerBusinessLogic.cs, OrderBusinessLogic.cs, etc. each calling their appropriately named cousin in the DataAccessLayer class library, i.e. CustomerDataAccess.cs, OrderDataAccess.cs. I want to create a web app using MVP and it doesn't seem so cut and dry as this. There are lots of opinions about where the business logic is supposed to be put in MVP and I'm not sure I've found a really great answer yet. I want this project to be easily testable, and I am trying to adhere to TDD methodologies as best I can. I intend to use MSTest and Rhino Mocks for testing. I was thinking of something like the following for my architecture: I'd use LINQ-To-SQL to talk to the database. WCF services to define data contract interfaces for the business logic layer. Then use MVP with ASP.NET Forms for the UI/BLL. Now, this isn't the start of this project, most of the LINQ stuff is already done, so its stuck. The WCF service would replace the existing DataAccessLayer assembly and the UI/BLL would replace the BusinessLogicLayer assembly etc. This sort of makes sense in my head, but its getting really late. Anyone that's traveled down this path have any guidance? Good links? Warnings? Thanks!

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• Project Architecture For Enhancing Legacy project.

  - by vijay.shad

  I am working on legacy project. Now the situation demands project to be divided into parts. What strategy I should follow to do this task. Description: The legacy project (A) is fully functional web application with almost well defined layers. But now i need to extend the project to a further enhancement. This project usage maven as build tool. But it is used only for dependency managements only. (project exported to war form inside eclipse). The new enhancement needs me to add new data table, new UI(jsp, css, js and images). What should be my strategy to enhance to application. My proposed design. I am planing to create two new projects Project B : Main Enhancement works will done in this project. Will have all layers like service layer, dao layer and UI layer in itself. And will be a web application in itself. Project C : Extract some common model and service code form project-A and create this project. This project will be added as dependency to both the projects. If my this approach is okay! Then i presume there will be problem be problem in deployment. These two projects will demand to deploy separately(currently tomcat is used). But I must deploy these two projects as one war. So, i need to have a plan to change the web.xml entries to have configurations for both projects. This will comes with some more complexities with project. What should be my design for the project? Does my plan sounds good.

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• Design: Website calling a webservice on the same machine

  - by Chris L

  More of a design/conceptual question. At work the decision was made to have our data access layer be called through webservices. So our website would call the webservices for any/all data to and from the database. Both the website & the webservices will be on the same machine(so no trip across the wire), but the database is on a separate machine(so that would require a trip across the wire regardless). This is all in-house, the website, webservice, and database are all within the same company(AFAIK, the webservices won't be reused by another other party). To the best of my knowledge: the website will open a port to the webservices, and the webservices will in turn open another port and go across the wire to the database server to get/submit the data. The trip across the wire can't be avoided, but I'm concerned about the webservices standing in the middle. I do agree there needs to be distinct layers between the functionality(such as business layer, data access layer, etc...), but this seems overly complex to me. I'm also sensing there will be some performance problems down the line. Seems to me it would be better to have the (DAL)assemblies referenced directly within the solution, thus negating the first port to port connection. Any thoughts(or links) both for and against this idea would be appreciated P.S. We're a .NET shop(migrating from vb to C# 3.5)

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• CGContext problems

  - by Peyman

  Hi I have a CALayer tree hierarchy A B C D where A is the view's root layer (and I create and add B,C and D layers. I am using the same delegate method `- (void) drawLayer:(CALayer *) theLayer inContext:(CGContextRef)context to provide content to each of these layers (implemented through a switch statement in the above method). At initiation A's content is drawn (A.contents) sequentially through these methods `- (void) drawLayer:(CALayer *) theLayer inContext:(CGContextRef)context -(void) drawCircle:(CALayer *) theLayer inContext:(CGContextRef)context where drawCircle does CGContextSaveGState(context); / draws circle and other paths here / CGContextRestoreGState(context); CGImageRef contentImage = CGBitmapContextCreateImage(context); theLayer.contents = (id) contentImage; CGImageRelease(contentImage); (i.e I save the Context, do the drawing, restore the context, make a bitmap of the context, update the layer's contents, in this case A's, then release the contentimage). When the user then clicks somewhere in the circle at touchesEnded:(NSSet*)touches withEvent:(UIEvent*)event delegate method I then try to paint the content of B by (still in touchesEnded:) CGContextRef context = UIGraphicsGetCurrentContext(); [self drawLayer:self.B inContext:context]; [self.B setNeedsDisplay]; the setNeedsDisplay call the delegate - drawLayer:(CALayer *) theLayer inContext:(CGContextRef)context again but this time the switch statement (using a layer flag) calls [self drawCircle:theLayer inContext:context]; with color red. The problem I am facing is that when -drawCircle: inContext: is called I get a long list of CGContext errors, starting with <Error>: CGContextSaveGState: invalid context and ending with CGBitmapContextCreateImage: invalid context I played around with making context the view's ivar and it worked so i am sure the context is the problem but I don't know what. I've tried CGContextFlush but it didn't help. Any help would be appreciated thank you

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• Neural Network with softmax activation

  - by Cambium

  This is more or less a research project for a course, and my understanding of NN is very/fairly limited, so please be patient :) ============== I am currently in the process of building a neural network that attempts to examine an input dataset and output the probability/likelihood of each classification (there are 5 different classifications). Naturally, the sum of all output nodes should add up to 1. Currently, I have two layers, and I set the hidden layer to contain 10 nodes. I came up with two different types of implementations 1) Logistic sigmoid for hidden layer activation, softmax for output activation 2) Softmax for both hidden layer and output activation I am using gradient descent to find local maximums in order to adjust the hidden nodes' weights and the output nodes' weights. I am certain in that I have this correct for sigmoid. I am less certain with softmax (or whether I can use gradient descent at all), after a bit of researching, I couldn't find the answer and decided to compute the derivative myself and obtained softmax'(x) = softmax(x) - softmax(x)^2 (this returns an column vector of size n). I have also looked into the MATLAB NN toolkit, the derivative of softmax provided by the toolkit returned a square matrix of size nxn, where the diagonal coincides with the softmax'(x) that I calculated by hand; and I am not sure how to interpret the output matrix. I ran each implementation with a learning rate of 0.001 and 1000 iterations of back propagation. However, my NN returns 0.2 (an even distribution) for all five output nodes, for any subset of the input dataset. My conclusions: o I am fairly certain that my gradient of descent is incorrectly done, but I have no idea how to fix this. o Perhaps I am not using enough hidden nodes o Perhaps I should increase the number of layers Any help would be greatly appreciated! The dataset I am working with can be found here (processed Cleveland): http://archive.ics.uci.edu/ml/datasets/Heart+Disease

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• VEMap and a GeoRSS feed(hosted separately)

  - by Alexis Abril

  The scenario is as follows: A WCF web service exists that outputs a valid GeoRSS feed. This lives in its own domain as a number of different applications have access to it. A web page(on a different site) has been created with an instance of a VEMap(Bing/Virtual Earth map object). Now, VEMap can accept an input feed in this format via the following: var layer = new VEShapeLayer(); var veLayerSpec = new VEShapeSourceSpecification(VEDataType.GeoRSS, "someurl", layer); map.ImportShapeLayerData(veLayerSpec, onComplete, true); onComplete is a callback function I'm using to replace the default pin graphic with something custom. The question is in regards to "someurl", which is a path to a local xml file containing the geographic information(georss simple format). I've realized this feed and the map must be hosted in the same domain, so I've created a generic handler that reads the remote feed and returns it in the same format. var veLayerSpec = new VEShapeSourceSpecification(VEDataType.GeoRSS, "/somelocalhandler.ashx", layer); When I do this, I get the VEMap error("z is null"). This is the same error one would receive when trying to access a remote feed. When I copy the feed into a local xml file(ie, "feed.xml") there is no error. The order of operations is currently: remote feed - local handler - VEMap import If I'm over complicating this procedure, let me know! I'm a bit new to the Bing Maps API and might have missed something. Any assistance is appreciated.

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• Why won't my CATiledLayer scroll in a UIScrollView after zooming?

  - by Brodie4598

  I'm currently having the following problem with CATiledLayer: when the view first loads, the scrolling works perfectly, but then when you zoom once, the view snaps to the anchor point (top left corner) and it can no longer scroll at all. The zooming works in that it will zoom in and out, but it will only zoom to the top left corner. My code is as follows: #import <QuartzCore/QuartzCore.h> #import "PracticeViewController.h" @implementation practiceViewController //@synthesize image; - (void)viewDidLoad { NSString *path = [[NSBundle mainBundle] pathForResource:@"H-5" ofType:@"jpg"]; NSData *data = [NSData dataWithContentsOfFile:path]; image = [UIImage imageWithData:data]; CGRect pageRect = CGRectMake(0, 0, image.size.width, image.size.height); CATiledLayer *tiledLayer = [CATiledLayer layer]; tiledLayer.anchorPoint = CGPointMake(0.0f, 1.0f); tiledLayer.delegate = self; tiledLayer.tileSize = CGSizeMake(1000, 1000); tiledLayer.levelsOfDetail = 6; tiledLayer.levelsOfDetailBias = 0; tiledLayer.bounds = pageRect; tiledLayer.transform = CATransform3DMakeScale(1.0f, -1.0f, 0.3f); myContentView = [[UIView alloc] initWithFrame:self.view.bounds]; [myContentView.layer addSublayer:tiledLayer]; UIScrollView *scrollView = [[UIScrollView alloc] initWithFrame:self.view.bounds]; scrollView.delegate = self; scrollView.contentSize = pageRect.size; scrollView.minimumZoomScale = .2; scrollView.maximumZoomScale = 1; [scrollView addSubview:myContentView]; [self.view addSubview:scrollView]; } - (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView { return myContentView; } - (void)drawLayer:(CALayer *)layer inContext:(CGContextRef)ctx { NSString *path = [[NSBundle mainBundle] pathForResource:@"H-5" ofType:@"jpg"]; NSData *data = [NSData dataWithContentsOfFile:path]; image = [UIImage imageWithData:data]; CGRect imageRect = CGRectMake (0.0, 0.0, image.size.width, image.size.height); CGContextDrawImage (ctx, imageRect, [image CGImage]); } @end

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• Spring - Transaction Readonly

  - by AAK

  Hello Gurus! Just wanted your expert opinions on declarative transaction management for Spring. Here is my setup - A. DAO Layer is Plain old JDBC using jdbcTemplete (No hibernate etc) B. Service Layer is POJO with declarative trasnactions as follows - save*, readonly=false, rollback for Throwable Things work fine with above setup. However when I say get*, readonly=true I see errors in my log file saying - Database connection cannot be marked as readonly. This happens for all get* methods in Service Layer. Now my questions - A. Do I have to say get* as readonly? All my get* methods are pure read DB operations. I do not wish to run them in any transaction context. How serious is the above error? B. When I remove the get* confiiguration, I do not see the errors, morever all my simple get* operations are performed without transactions. Is this the way to go? C. Why would anyone want to have transactional methods where readonly = true? Is there any practical significance of this configuration? Thank you! As always your resposes are much appreciated!

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• SQL Alchemy MVC and cross controller joins

  - by Khorkrak

  When using SQL Alchemy for abstracting your data access layer and using controllers as the way to access objects from that abstraction layer, how should joins be handled? So for example, say you have an Orders controller class that manages Order objects such that it provides getOrder, saveOrder, etc methods and likewise a similar controller for User objects. First of all do you even need these controllers? Should you instead just treat SQL Alchemy as "the" thing for handling data access. Why bother with object oriented controller stuff there when you instead have a clean declarative way to obtain and persist objects without having to write SQL directly either. Well one reason could be that perhaps you may want to replace SQL Alchemy with direct SQL or Storm or whatever else. So having controller classes there to act as an intermediate layer helps limit what would need to change then. Anyway - back to the main question - so assuming you have these two controllers, now lets say you want the list of orders for a certain set of users meeting some criteria. How do you go about doing this? Generally you don't want the controllers crossing domains - the Orders controllers knows only about Orders and the User controller just about Users - they don't mess with each other. You also don't want to go fetch all the Users that match and then feed a big list of user ids to the Orders controller to go find the matching Orders. What's needed is a join. Here's where I'm stuck - that seems to mean either the controllers must cross domains or perhaps they should be done away with altogether and you simply do the join via SQL Alchemy directly and get the resulting User and / or Order objects as needed. Thoughts?

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• Custom UIView using CALayers disappears after 180º rotation or navigation controller pop

  - by Steve Madsen

  I have a created a custom UIView subclass that is exhibiting some strange behavior. It is a spinning wheel selector, and for performance reasons it is drawn entirely into two CALayer instances. The bottom layer is the wheel itself, which is rotated using setAffineTransform: according to touches. The top layer is eye candy. drawRect: is fairly simple. If the control hasn't been drawn yet (or it's been invalidated), it calls a method that creates the images and assigns them to the layer contents property. - (void) drawRect:(CGRect)rect { if (imageLayer == nil) { [self drawIntoImageLayer]; } [self updateWheelRotation]; } When the view controller using this view first appears, everything is fine. There are two instances where the view completely disappears, however: If the device is rotated a full 180°. After a view controller is popped off the navigation stack and the view becomes visible again. drawRect: is not called either time. Interestingly enough, it IS called after a 90° orientation change, and that causes the view to re-appear. How can I ensure that a custom view using CALayers is redrawn properly in these situations?

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• Patterns for non-layered applications

  - by Paul Stovell

  In Patterns of Enterprise Application Architecture, Martin Fowler writes: This book is thus about how you decompose an enterprise application into layers and how those layers work together. Most nontrivial enterprise applications use a layered architecture of some form, but in some situations other approaches, such as pipes and filters, are valuable. I don't go into those situations, focussing instead on the context of a layered architecture because it's the most widely useful. What patterns exist for building non-layered applications/parts of an application? Take a statistical modelling engine for a financial institution. There might be a layer for data access, but I expect that most of the code would be in a single layer. Would you still expect to see Gang of Four patterns in such a layer? How about a domain model? Would you use OO at all, or would it be purely functional? The quote mentions pipes and filters as alternate models to layers. I can easily imagine a such an engine using pipes as a way to break down the data processing. What other patterns exist? Are there common patterns for areas like task scheduling, results aggregation, or work distribution? What are some alternatives to MapReduce?

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• How do i pass arbitary date format from C# to sql backend

  - by Jims

  I have a datetime field for the transaction date in the back end. So I am passing that date from front C#.net, in the below format: 2011-01-01 12:17:51.967 to do this I have written: presentation layer: string date = DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss.fff", CultureInfo.InvariantCulture); PropertyClass prp=new PropertyClass(); Prp.TransDate=Convert.ToDateTime(date); PropertyClass structure: Public class property { private DateTime transdate; public DateTime TransDate { get { return transdate; } set { transdate = value; } } } From DAL layer passing the TransactionDate like this: Cmd.Parameters.AddWithValue("@TranSactionDate”, SqlDbType.DateTime).value=propertyobj.TransDate; While debugging from presntation layer: string date = DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss.fff", CultureInfo.InvariantCulture); in this I am getting correct expected date format, but when debugs goes to this line Prp.TransDate=Convert.ToDateTime(date); again date format changing to 1/1/2011. But my backend sql datefield wants the date paramter 2011-01-01 12:17:51.967 in this format otherwise throwing exception invalid date format. Note: While passing date as string without converting to datetime getting exceptions like: System.Data.SqlTypes.SqlTypeException: SqlDateTime overflow. Must be between 1/1/1753 12:00:00 AM and 12/31/9999 11:59:59 PM. at System.Data.SqlTypes.SqlDateTime.FromTimeSpan(TimeSpan value) at System.Data.SqlTypes.SqlDateTime.FromDateTime(DateTime value) at System.Data.SqlTypes.SqlDateTime..ctor(DateTime value) at System.Data.SqlClient.MetaType.FromDateTime(DateTime dateTime, Byte cb) at System.Data.SqlClient.TdsParser.WriteValue(Object value, MetaType type, Byte scale, Int32 actualLength, Int32 encodingByteSize, Int32 offset, TdsParserStateObject stateObj) at System.Data.SqlClient.TdsParser.TdsExecuteRPC(_SqlRPC[] rpcArray, Int32 timeout, Boolean inSchema, SqlNotificationRequest notificationRequest, TdsParserStateObject stateObj, Boolean isCommandProc)

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