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  • How do I recover from an unchecked exception?

    - by erickson
    Unchecked exceptions are alright if you want to handle every failure the same way, for example by logging it and skipping to the next request, displaying a message to the user and handling the next event, etc. If this is my use case, all I have to do is catch some general exception type at a high level in my system, and handle everything the same way. But I want to recover from specific problems, and I'm not sure the best way to approach it with unchecked exceptions. Here is a concrete example. Suppose I have a web application, built using Struts2 and Hibernate. If an exception bubbles up to my "action", I log it, and display a pretty apology to the user. But one of the functions of my web application is creating new user accounts, that require a unique user name. If a user picks a name that already exists, Hibernate throws an org.hibernate.exception.ConstraintViolationException (an unchecked exception) down in the guts of my system. I'd really like to recover from this particular problem by asking the user to choose another user name, rather than giving them the same "we logged your problem but for now you're hosed" message. Here are a few points to consider: There a lot of people creating accounts simultaneously. I don't want to lock the whole user table between a "SELECT" to see if the name exists and an "INSERT" if it doesn't. In the case of relational databases, there might be some tricks to work around this, but what I'm really interested in is the general case where pre-checking for an exception won't work because of a fundamental race condition. Same thing could apply to looking for a file on the file system, etc. Given my CTO's propensity for drive-by management induced by reading technology columns in "Inc.", I need a layer of indirection around the persistence mechanism so that I can throw out Hibernate and use Kodo, or whatever, without changing anything except the lowest layer of persistence code. As a matter of fact, there are several such layers of abstraction in my system. How can I prevent them from leaking in spite of unchecked exceptions? One of the declaimed weaknesses of checked exceptions is having to "handle" them in every call on the stack—either by declaring that a calling method throws them, or by catching them and handling them. Handling them often means wrapping them in another checked exception of a type appropriate to the level of abstraction. So, for example, in checked-exception land, a file-system–based implementation of my UserRegistry might catch IOException, while a database implementation would catch SQLException, but both would throw a UserNotFoundException that hides the underlying implementation. How do I take advantage of unchecked exceptions, sparing myself of the burden of this wrapping at each layer, without leaking implementation details?

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  • Accessing the DI container from anywhere

    - by ChrisR
    I've implemented the Symfony2 Dependency Injection container in my Zend Framework project and it works fine in the MVC layer of my application. I've initialized the DIC in my bootstrap and can access it anywhere by calling: Zend_Controller_Front::getInstance()->getParam('bootstrap')->getDic() The problem is that there are some parts of my application that do not utilize the Zend Framework application/MVC layer. My CLI tools for example. I could perfectly initialize a new DIC there but that would just be some copy paste work from the Bootstrap file which is asking for trouble down the road (DRY principles, etc) Is it a better solution to make my DIC available in the Zend_Registry or as a singleton called by a static method DIC::getInstance() for example? I know Registry and singletons are considered bad things but the DIC is such a high level part of the application that I will probably never run into the problems that make it a bad thing. Is this a good solution or are there better ways of accomplishing a globally accessible DIC?

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  • Should I use DTOs as my data models in MVVM?

    - by JonC
    I'm currently working on what will be my first real foray into using MVVM and have been reading various articles on how best to implement it. My current thoughts are to use my data models effectively as data transfer objects, make them serializable and have them exist on both the client and server sides. It seems like a logical step given that both object types are really just collections of property getters and setters and another layer in between seems like complete overkill. Obviously there would be issues with INotifyPropertyChanged not working correctly on the server side as there is no ViewModel to which to communicate, but as long as we are careful about constructing our proper domain model objects from data models in the service layer and not dealing the the data models on the server side I don't think it should be a big issue. I haven't found too much info about this approach in my reading, so I would like to know if this is a pretty standard thing, is this just assumed to be the de facto way of doing MVVM in a multi-tier environment? If I've got completely the wrong idea about things then thoughts on other approaches would be appreciated too.

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  • End User Ad-Hoc Reporting Tool: Microsoft SQL Server Management Studio or Microsoft Access?

    - by schultkl
    Our centralized IT department has suggested two primary ad hoc query tools for our general user base of approximately 200 staff members: Microsoft SQL Server Management Studio 2008 (SSMS) Microsoft Access 2003 Environment The backend database is a read-only Microsoft SQL Server 2005 database. The schema is 400+ tables; allowing access to the raw data for our general staff would be a disaster. We will be building an "abstraction layer" over the raw data for our general staff to run ad hoc queries against. The abstraction layer will most likely contain a number of views. A number of users have basic knowledge in Microsoft Access; none have used SSMS. Which of the above tools (or alternative) would be best for a decidedly non-techie user base of approximately 200 people? What are the pros and cons of each? Also, the IT department has suggested teaching people T-SQL so they may use SSMS. Is this reasonable?

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  • What simple methods are there to wrap a c++ based object model with a COM interface

    - by Rich
    I have a pre-existing c++ object model which represents the business layer tier of an application. I want to be able to expose the object model to applications written in other languages i.e vbscript, VB, javascript etc. I believe the best way of doing this is to wrap the business objects with a COM layer. What fast and effective methods are there for doing this. Any advice, links to practical "How to" documentation would be very much appreciated. Because I'm starting a bounty on this , here's a few extra guidelines for potential bounty hunters :- 1)I've decided on an ATL approach 2)I'm now specifically looking for links to really good "how to and quickly" documentation on wrapping a pre-existing c++ object model to make it useable by a scripting language like javascript 3) Something with small working examples showing me what code needs to be added to what files, e.g what goes into the cpp , idl and hpp/h etc. It' must include an example I can compile test and change to get a better understanding.

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  • Is it OK to pass SQLCommand as a parameter?

    - by TooFat
    I have a Business Layer that passes a Conn string and a SQLCommand to a Data Layer like so public void PopulateLocalData() { System.Data.SqlClient.SqlCommand cmd = new System.Data.SqlClient.SqlCommand(); cmd.CommandType = System.Data.CommandType.StoredProcedure; cmd.CommandText = "usp_PopulateServiceSurveyLocal"; DataLayer.DataProvider.ExecSQL(ConnString, cmd); } The DataLayer then just executes the sql like so public static int ExecSQL(string sqlConnString, System.Data.SqlClient.SqlCommand cmd) { int rowsAffected; using (SqlConnection conn = new SqlConnection(sqlConnString)) { conn.Open(); cmd.Connection = conn; rowsAffected = cmd.ExecuteNonQuery(); cmd.Dispose(); } return rowsAffected; } Is it OK for me to pass the SQLCommand as a parameter like this or is there a better more accepted way of doing it. One of my concerns is if an error occurs when executing the query the cmd.dispose line will never execute. Does that mean it will continue to use up memory that will never be released?

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  • LLBLGen and the repository pattern

    - by user137348
    I was wondering if building a repository on the top LLBLGen (adapter) is a good idea. I don't want to overengineer and reinvent the wheel again. The DataAccessAdapter class could be some kind of a generic repository.It has all the CRUD methods you need. But on the other side for a larger project it could be good to have a layer between your ORM and service layer. I'd like to hear your opinions, if your using the repository pattern with LLBLGen,if yes why if no why not. If you have some implementation, post it please.

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  • Can hitTestPoint be used with local coordinates at all?

    - by mars
    In AS3 I have a game where a vehicle rotates to the direction of the cursor, but when it "moves", its sprite stays stationary in the middle of the stage while the map layer below it actually moves, causing the illusion of movement of the vehicle on the map. There are obstacles on the map that the vehicle cannot pass. The obstacles are in a movie clip that is a part of the map layer and move with it. hitTestPoint seems only to be able to check if the obstacle clip is touching points on the stage rather than points on the map, meaning that I cannot feed it the same coordinates I use to check the map boundaries, which are points on the map. I don't think I can use localToGlobal because the function I use to check obstacle collisions does not have access to a reference to the obstacle movie clip. Is there a way in these conditions to force hitTestPoint to use its local coordinate system on the map? I have included a diagram:

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  • Communication between layers in an application

    - by Petar Minchev
    Hi guys! Let's assume we have the following method in the business layer. What's the best practice to tell the UI layer that something went wrong and give also the error message? Should the method return an empty String when it was OK, otherwise the error message, or should it throw another exception in the catch code wrapping the caught exception? If we choose the second variant then the UI should have another try,catch which is too much try,catch maybe. Here is a pseudocode for the first variant. public String updateSomething() { try { //Begin transaction here dataLayer.do1(); dataLayer.do2(); dataLayer.doN(); } catch(Exception exc) { //Rollback transaction code here return exc.message; } return ""; } Is this a good practice or should I throw another exception in the catch(then the method will be void)?

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  • How to find points that intersect an envelope of a line, but not the line itself?

    - by Jacques Bosch
    I have 2 layers. A lines layer and a points layer. For any given line, how can I find the points that intersect the envelope of the line, but not the line itself, or more specifically, not the to point or from point of the line. I can obviously find all the points that intersect the line's envelope, and then do 1 by 1 tests on the found points to see if they intersect the to or from points of the line, but I was hoping there is an easier, faster way to do something of this nature.

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  • Is there any framework for Windows Forms, DB driven application development/prototyping?

    - by dolzenko
    I'm writing simple database driven application, 80% of functionality is CRUD operations on about 15 tables. Coming from web development background I figured I can cover almost all of these CRUD cases with Rails scaffolding or say Django admins. So I started to look around for Rails/Django-like framework but for Windows Forms applications (ofcourse I understand that "rich client" application development significantly differs from a web development and I'm not expecting anything really similar). I was surprised that except for a variety of ORMs (let's call it Model-layer) it seems like I'm left with little choice when it comes to View-Controller layer. Maybe I'm missing something? PS. I evaluated Visual Studio DataSet Designer, but it seems to work only for the most simple cases, and requires additional code for any slightly nontrivial task. (added) so far I've found: TrueView for .NET (thanks to Vijay Patel) NConstruct

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  • Create generic class instance throws TypeLoadException

    - by Elisa
    My TestLayer class has the namespace: "BLL.Infrastructure.TestLayer" and is inside the assembly: "BLL" public class LayerFactory<T, U> { public static IBaseLayer<T, U> Get() { var obj = Activator.CreateInstance("BLL", "BLL.Infrastructure.TestLayer", new object[] { (IBaseLayer<T, U>)null }); } } When I run the code the Activator throws an TypeLoadException with no more details Thats the concrete class it should create: GenericBaseLayer implements the IBaseLayer. public class TestLayer<T, U> : GenericBaseLayer<MyRequest, MyInfo.ActionType> { public TestLayer(IBaseLayer<MyRequest, MyInfo.ActionType> layer) : base(layer) { } } What do I wrong?

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  • help in security assignment

    - by scatman
    i have to write a program that sniffs network packets (part1-the simple part). and i have to update the program (part2) so that it will be able to terminate connections. the specific requirements are: construct raw packets by specifying data link layer and network layer information including appropriate source and destination MAC and IP addresses. These packets are intended to terminate the connection. To do so, you should used SOCK_RAW as the socket type to be able to set the header information by yourself. can anybody give me some ideas on the second part? should i hijack the session,apply a dos attack on one of the users?? all i need is some tips of how to terminate the connection. i am using c programming language. and this is a course assignment for the security course.

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  • Visual Studio 2010 UML Tools. How do they integrate with the code? For small/mid size products is t

    - by punkouter
    I just got a book that goes over all the VS2010 tools. Most I have never used like load testing/web testing, UML Tools, Layer Diagrams.... Has anyone had any real world experience with using these VS2010 tools like the UML diagramming? I am wondering if it is something that would really be useful starting a new project or is it just busy work that no one ever uses once they are made? How are the UML diagrams integrated with the rest of development in VS2010 ? The last project we just made some really basic Visio diagrams but maybe this is better. Alot of VS2010 Ultimate tools are over kill (layer diagram) for small/mid level projects it seems. UML seems to be one of those things I hear about past 10 years but never seem to use.

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  • fscommand2 support in Actionscript 3.0 ?

    - by Andhravaala
    Hi All, I am very new to Action Script. I am using Flash Professional CS5 with ActionScript 3.0. The problem is, When I am trying use fscommand2 function, Compiler throwing an error saying: Scene 1, Layer 'Layer 1', Frame 1, Line 7 1180: Call to a possibly undefined method fscommand2. But, I am able to use fscommand. But, it will not fulfill my requirement to get Device(Mobile) properties like DeviceID etc. Please help me in using fscommand2 or any equivalent API support in ActionScript 3.0. Thanks in advance.

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  • How to integrate access control with my ORM in a .net windows form application?

    - by Ying
    I am developing a general database query tools, a .Net 3.5 Windows Form application. In order to make the presentation layer is independent of the database layer. I use an ORM framework, XPO from DevExpress. But, I have no access control function built in. I surfed Internet and I found in WCF Data Services, there is an interesting concept, Interceptor, which is following AOP(Aspect Oriented Programming). I am wondering who has such an experience to build access control in ORM. My basic requirement is : It should be a general method and controlled by users in runtime. So any hard coding is not acceptable. It could be based on attribute, database table, or even an external assembly. I am willing to buy a ready solution. According to the idea of AOP, an access control function can be integrated with existing functions easily and nearly not knowingly to the previous developer;) Any suggestions are welcome.

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  • Maintaining last stage when rotating through CATransform3DIdentity

    - by Mikhail Naimy
    Hi. i am rotating imageview through following code.it rotates fine..but when i rotate again , Imageview goes to previous angle( which is in initial stage) and then it rotates...any one can help in this?rotationTransform has been declared as CABasicAnimation* rotationAnimation in .h file.... - (void) touchesBegan:(NSSet*)touches withEvent:(UIEvent*)event { UITouch *touch = [touches anyObject]; startTouchPosition = [touch locationInView:self.view]; } - (void) touchesMoved:(NSSet*)touches withEvent:(UIEvent*)event { UITouch *touch = [[event allTouches] anyObject]; location = [touch locationInView:self.view]; currentLocationRadians = atan2f(location.y - self.view.frame.size.height/2, location.x - self.view.frame.size.width/2); lastLocationRadians = atan2f(startTouchPosition.y - self.view.frame.size.height/2, startTouchPosition.x - self.view.frame.size.width/2); rotationTransform = CATransform3DIdentity; rotationTransform = CATransform3DRotate(rotationTransform, currentLocationRadians-lastLocationRadians + rad, 0.0, 0.0, 1.0); _imgview.layer.transform = rotationTransform; } - (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event { rotationTransform = _imgview.layer.transform; }

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  • Looking for design patterns to isolate framework layers from each other

    - by T Reddy
    Hi, I'm wondering if anyone has any experience in "isolating" framework objects from each other (Spring, Hibernate, Struts). I'm beginning to see design "problems" where an object from one framework gets used in another object from a different framework. My fear is we're creating tightly coupled objects. For instance, I have an application where we have a DynaActionForm with several attributes...one of which is a POJO generated by the Hibernate Tools. This POJO gets used everywhere...the JSP populates data to it, the Struts Action sends it down to a Service Layer, the DAO will persist it...ack! Now, imagine that someone decides to do a little refactoring on that POJO...so that means the JSP, Action, Service, DAO all needs to be updated...which is kind of painful...There has got to be a better way?! There's a book called Core J2EE Patterns: Best Practices and Design Strategies (2nd Edition)...is this worth a look? I don't believe it touches on any specific frameworks, but it looks like it might give some insight on how to properly layer the application... Thanks!

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  • Why are all my masked views unmasked in my view snapshot?

    - by mystify
    I'm taking a snapshot of an view. This view has got some subviews which have layer masks applied to them. For some reason, those masks take no effect in the snapshot and the masked parts are completely visible. UIGraphicsBeginImageContext(theView.frame.size); [theView.layer renderInContext:UIGraphicsGetCurrentContext()]; UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); I assume this is a bug in the framework. But maybe it's not? Did I do anything wrong here?

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  • How to permanently leave a CALayer rotated at its final location?

    - by David
    Hello, I am trying to rotate a CALayer to a specific angle however, once the animation is done, the layer jumps back to its original position. How would I rotate the layer properly so that it stays at its final destination? Here is the code that I am using CABasicAnimation *rotationAnimation =[CABasicAnimation animationWithKeyPath:@"transform.rotation.z"]; //Rotate about z-axis [rotationAnimation setFromValue:[NSNumber numberWithFloat:fromDegree]]; [rotationAnimation setToValue:[NSNumber numberWithFloat:toDegree]]; [rotationAnimation setDuration:0.2]; [rotationAnimation setRemovedOnCompletion:YES]; [rotationAnimation setFillMode:kCAFillModeForwards]; Any suggestions? Thank you.

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  • addsubview animation works only first time

    - by Priya
    I am trying add subview with animation effect using the code which work fine for the first time below. CATransition *transition = [CATransition animation]; transition.duration = 1.0; transition.type = kCATransitionMoveIn; transition.subtype = kCATransitionFromRight; [newView.layer removeAllAnimations] [newView.layer addAnimation:transition forKey:nil]; [self.masterview addSubview:newView]; There is a back button in newView which removes the View from the superview. [newView removeFromSuperview]; Now when I try adding newView as subview again using the above code,its first adds the view as a subview(without animation) and again with animation.

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  • Setting Corner Radius on UIImageView not working

    - by MarkPowell
    I'm at a bit of a loss. I've used the layer property of UIView to round the corners of multiple elements in my app. However, this one UIImageView is simply not complying. Not sure what I am missing. The UIImageView (called previewImage) is contained in a Table View Cell. I've tried setting the cornerRadius property multiple location (in the cell itself and in the controller that creates the cell) to no avail. static NSString *CellIdentifier = @"MyTableViewCell"; MyTableViewCell *cell = (MyTableViewCell *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier]; if (cell == nil) { NSArray *topLevelObjects = [[NSBundle mainBundle] loadNibNamed:CellIdentifier owner:self options:nil]; cell = [topLevelObjects objectAtIndex:0]; cell.previewImage.layer.cornerRadius = 20; //Made it 20 to make sure it's obvious. } Is there something about the way cells are loaded that I'm missing?

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  • Ways to make your WCF services compatible with non-.NET consumers

    - by Mayo
    I'm working on adding a WCF services layer to my existing .NET application. This layer will be hosted in IIS and will be consumed by a variety of UIs, at least one of which will not use Microsoft technologies. I can make a Web service in WCF that is consumed by my .NET application. However, I'm concerned about things that work in the .NET world but not with other technologies. For example, simply throwing an exception from my WCF service works fine in .NET. But according to this article, one should approach exception handling with fault contracts to ensure compatibility with non-.NET consumers. The author labels this lack of foresight as The Fallacy of the .NET-Only World. Does anyone have any high level suggestions or links to articles that cover interoperability between WCF and non-.NET consumers? I realize I'm potentially working against the YAGNI principle. I'm only really looking to avoid things that will be incredibly difficult to overcome later when the developers of the non-.NET consumer report problems to me.

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  • How to know the Geometry coordinates for google Maps

    - by Sam
    I found a sample script on Google Code about : Google Maps Javascript API V3 Overlays - http://code.google.com/apis/maps/documentation/javascript/overlays.html#OverlaysOverview And I want to apply this code to other countries (France, spain...) but I don't know where/how to find the Geometry code like in this script (see commented line) Here is the code: var australia = new google.maps.LatLng(-25, 133); map = new google.maps.Map(document.getElementById('map_canvas'), { center: australia, zoom: 4, mapTypeId: google.maps.MapTypeId.ROADMAP }); layer = new google.maps.FusionTablesLayer({ query: { select: 'geometry', from: '815230' // This one }, styles: [{ polygonOptions: { fillColor: "#00FF00", fillOpacity: 0.3 } }, { where: "birds > 300", polygonOptions: { fillColor: "#0000FF" } }, { where: "population > 5", polygonOptions: { fillOpacity: 1.0 } }] }); layer.setMap(map); P.S. I tried to change the google.maps.LatLng(-25, 133) to France Lat&Long but this is used only to center the map on that position. Thank you for your help

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  • How we should load theMFMailComposeViewController in cocos2d ?

    - by srikanth rongali
    I am writing an app in using cocos2d. This method I have written for the selector goToFirstScreen: . The view is in landscape mode. I need to send an email. So, I need to launch the MFMailComposeViewController. I need it in portrait mode. But, the control is not entering in to viewDidLoad of the mailMe class. The problem is in goToScreen: method. But, I do not get where I am wrong ? -(void)goToFirstScreen:(id)sender { CCScene *Scene = [CCScene node]; CCLayer *Layer = [mailME node]; [Scene addChild:Layer]; [[CCDirector sharedDirector] setAnimationInterval:1.0/60]; [[CCDirector sharedDirector] pushScene: Scene]; } Thank you .

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