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  • What is the relationship between the business logic layer and the data access layer?

    - by Matt Fenwick
    I'm working on an MVC-ish app (I'm not very experienced with MVC, hence the "-ish"). My model and data access layer are hard to test because they're very tightly coupled, so I'm trying to uncouple them. What is the nature of the relationship between them? Should just the model know about the DAL? Should just the DAL know about the model? Or should both the model and the DAL be listeners of the other? In my specific case, it's: a web application the model is client-side (javascript) the data is accessed from the back-end using Ajax persistence/back-end is currently PHP/MySQL, but may have to switch to Python/GoogleDataStore on the GAE

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  • Design Patterns - Service Layer

    - by garfbradaz
    I currently reading a lot about Design Patterns and I have been watching various Pluralsight videos from their library. Now so far I have learnt the following: Repository Pattern Unit of Work Pattern Abstract Factory Pattern Reading the awesome "DI in .NET" book Now I read lot about Services and Service Layers and wanted some advice about the best place to read up and learn about these. I presume this fits into Domain Driven Design and I should start there? The term "Service" just seem to be used widely within IT and it can be confusing the exact meaning. So my questions is: What is the Service Layer Where is the best place to learn about them. I know there are probably tonnes of interweb/books/blogs on the subject, but some good areas to start from would be nice. If I'm being too vague, let me know.

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  • C# and SQL data layer code generator

    I've created a simple yet efficient tool to help generate stored procedures and a C# data access layer from a table.  Instead of using an ORM, this uses standard ADO .NET (SqlConnection, SqlDataReader, etc).  Check it out at www.asteio.com.  It's saved me a ton of time and I'm hoping it does the same for you....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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  • Can Layer Masks Achieve This Effect

    - by Julian
    If you look at the image below you will see the player surrounded by a dotted yellow box. The dotted yellow box is also part of the player and represented a portion of the player being masked from both rendering and affected by physics. My question is if layer masks in Unity can achieve the following effect. -In Area 1, the red box/animations of the player are visible and the rigidbody of this shape is affected by all Physics. -Any portion of the player that enters Area 2 makes the larger yellow box within the area become visible (and affected by physics) and vice versa for any portion of the smaller red box that enters. -This can persist when both entering and leaving either area from any direction. Thank you for any help!

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  • PHP - Data Access Layer

    - by scarpacci
    I am currently reviewing a code base and noticed that a majority of the calls (along with DB connections) are just buried inside the PHP scripts. I would have assumed that like other languages they would have developed some sort of data access layer (Like I would do in .Net or Java) for all of the communication to the DB (or implemented MVC, etc). Is this still a common pattern in PHP or is there alternative methodologies/patterns for this technology? I am just trying to understand why the subs would have developed it this way. Any insight/info on how experienced developers design an approach data access in PHP would be very much appreciated.

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  • Organizing your Data Access Layer

    - by nighthawk457
    I am using Entity Framework as my ORM in an ASP.Net application. I have my database already created so ended up generating the entity model from it. What is a good way to organize files/classes in the data access layer. My entity framework model is in a class library and I was planning on adding additional classes per Entity(i.e per database table) and putting all the queries related to those tables in their respective classes. I am not sure if this is a right approach and if it is then where do the queries requiring data from multiple tables go? Am I completely wrong in organizing my files based on entities/tables and should I organize them based on functional areas instead.

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  • Motivation for service layer (instead of just copying dlls)?

    - by BornToCode
    I'm creating an application which has 2 different UIs so I'm making it with a service layer which I understood is appropriate for such case. However I found myself just creating web methods for every single method I have in the BL layer, so the services basically built from methods that looks like this: return customers_bl.Get_Customer_Prices(customer_id); I understood that a main point of the service layer is to prevent duplication of code so I asked myself - well, why not just import the BL.dll (and the DAL.dll) to the other UI, and whenever making a change re-copy the dll files, it might not be so 'neat', but is the all purpose of the service layer to prevent this? {I know something is wrong in my approach, I'm probably missing the importance of service layer, I'd like to get more motivation to create another layer, especially because as it is I found that many of my BL functions ALREADY looks like: return customers_dal.Get_Customer_Prices(cust_id) which led me to ask: was it really necessary to create the BL just because on several functions I actually have LOGIC inside the BL?} so I'm looking for more motivation to creating ONE MORE layer, I'm sure it's not just to make it more convenient that I won't have to re-copy the dlls on changes? Am I grasping it wrong? Any simple guidelines on how to design service layer (corresponding to all the BL layer functions or not? any simple example?) any enlightenment on the subject?

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  • Motivation for a service layer (instead of just copying dlls)?

    - by BornToCode
    I'm creating an application which has 2 different UIs so I'm making it with a service layer which I understood is appropriate for such scenario. However I found myself just creating web methods for every single method I have in the BL layer, so the services basically built from methods that looks like this: return customers_bl.Get_Customer_Prices(customer_id); I understood that a main point of the service layer is to prevent duplication of code so I asked myself - why not just import the BL.DLL (and the dal.dll) to the other UI, and whenever making a change re-copy the dlls, it might not be so 'neat', but still less hassle than one more layer? {I know something is wrong in my approach, I'm probably missing the importance of service layer, I'd like to get more motivation to create another layer, especially because as it is I found that many of my BL functions ALREADY looks like: return customers_dal.Get_Customer_Prices(cust_id) which led me to ask: was it really necessary to create the BL just because on several functions I actually have LOGIC inside the BL?} so I'm looking for more motivation to creating ONE MORE layer, I'm sure it's not just to make it more convenient that I won't have to re-copy the dlls on changes? Am I grasping it wrong? Any simple guidelines on how to design service layer (corresponding to all the BL layer functions or not? any simple example?) any enlightenment on the subject?

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  • Passing Request Object into Service Layer

    - by SpringTrickery
    In a spring mvc + spring core app, we have have a view layers, a facade, a service layer, a dao layer and a stored-proc based persistance layer. The service layer is unaware of the clients that utilitize its methods. Is it fine to propagate raw http requests into the service layer? Or is it bad practice and a violation of the loose coupling principles? If it is, then what's a clean workaround?

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  • How to take a layer's snapshot with mask layer?

    - by OpenThread
    I added a mask to UIView's layer: CGImageRef maskImageRef = [UIImage imageNamed:"Icon.png"].CGImage; CALayer maskLayer = [CALayer layer]; maskLayer.contents = (__bridge id)maskImageRef; self.layer.mask = maskLayer; Then I use this code to get snapshot from a UIView: [self.layer renderInContext:mainViewContentContext]; But the mask wasn't drawn. How to draw self.layer with mask? Special thx!

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  • Implement service layer in MVC

    - by Dan H
    We have a defined service layer hosted in WCF. We are now building a website that will need to use the services functionality. The website is being written in ASP.NET MVC 4 and I'm trying to decide how to reference the WCF service from the MVC app. It's a large complex website and it will be changing on a weekly basis. My first reaction is to abstract out the service references (About 7 services on this one WCF host) and create a service ref facade library with which the website interacts. But, I don't know exactly how to use the service facade in MVC. I'm starting to think the Models will be responsible for it because when the controller gets a model, that model should call the service (if needed) and return what the controller asked. I'm trying to avoid having the MVC app know details of the service references. So, I could have a model factory that creates whatever model the controllers need and they can use the service facade to accomplish it. Is this a good plan, or am I off track?

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  • Web Application: Combining View Layer Between PHP and Javascript-AJAX

    - by wlz
    I'm developing web application using PHP with CodeIgniter MVC framework with a huge real time client-side functionality needs. This is my first time to build large scale of client-side app. So I combine the PHP with a large scale of Javascript modules in one project. As you already know, MVC framework seperate application modules into Model-View-Controller. My concern is about View layer. I could be display the data on the DOM by PHP built-in script tag by load some data on the Controller. Otherwise I could use AJAX to pulled the data -- treat the Controller like a service only -- and display the them by Javascript. Here is some visualization I could put the data directly from Controller: <label>Username</label> <input type="text" id="username" value="<?=$userData['username'];?>"><br /> <label>Date of birth</label> <input type="text" id="dob" value="<?=$userData['dob'];?>"><br /> <label>Address</label> <input type="text" id="address" value="<?=$userData['address'];?>"> Or pull them using AJAX: $.ajax({ type: "POST", url: config.indexURL + "user", dataType: "json", success: function(data) { $('#username').val(data.username); $('#dateOfBirth').val(data.dob); $('#address').val(data.address); } }); So, which approach is better regarding my application has a complex client-side functionality? In the other hand, PHP-CI has a default mechanism to put the data directly from Controller, so why using AJAX?

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  • C# XNA: Effecient mesh building algorithm for voxel based terrain ("top" outside layer only, non-destructible)

    - by Tim Hatch
    To put this bluntly, for non-destructible/non-constructible voxel style terrain, are generated meshes handled much better than instancing? Is there another method to achieve millions of visible quad faces per scene with ease? If generated meshes per chunk is the way to go, what kind of algorithm might I want to use based on only EVER needing the outer layer rendered? I'm using 3D Perlin Noise for terrain generation (for overhangs/caves/etc). The layout is fantastic, but even for around 20k visible faces, it's quite slow using instancing (whether it's one big draw call or multiple smaller chunks). I've simplified it to the point of removing non-visible cubes and only having the top faces of my cube-like terrain be rendered, but with 20k quad instances, it's still pretty sluggish (30fps on my machine). My goal is for the world to be made using quite small cubes. Where multiple games (IE: Minecraft) have the player 1x1 cube in width/length and 2 high, I'm shooting for 6x6 width/length and 9 high. With a lot of advantages as far as gameplay goes, it also means I could quite easily have a single scene with millions of truly visible quads. So, I have been trying to look into changing my method from instancing to mesh generation on a chunk by chunk basis. Do video cards handle this type of processing better than separate quads/cubes through instancing? What kind of existing algorithms should I be looking into? I've seen references to marching cubes a few times now, but I haven't spent much time investigating it since I don't know if it's the better route for my situation or not. I'm also starting to doubt my need of using 3D Perlin noise for terrain generation since I won't want the kind of depth it would seem best at. I just like the idea of overhangs and occasional cave-like structures, but could find no better 'surface only' algorithms to cover that. If anyone has any better suggestions there, feel free to throw them at me too. Thanks, Mythics

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  • The Differences between MAC Address and Network Layer Address

    A Mac address is a fixed number associated with a NICs onboard memory. It is initially assigned at the factory. The MAC address is broken up into 2 parts. The first part is the Block id which is six digit sequences that is unique to each vender. The second section is the device id which is created and assigned by the manufacture. A Network layer address is different because there format based on the type of protocol and network used. Also, there unique id is based on a hierarchal addressing theme on subsets of data  and narrowing it down. Just like in an address you can narrow down your house, for example: Florida, Boca Raton, 33428, SW 53th street states that you live in Florida. You also live in the area located in Florida called Boca Raton and you are also in the area of 33428 which is located in Boca Raton. Finally you live on SW 8th street which is in the area of 33428 which is located in Boca Raton which is also located in Florida.

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  • Service layer coupling

    - by Justin
    I am working on writing a service layer for an order system in php. It's the typical scenario, you have an Order that can have multiple Line Items. So lets say a request is received to store a line item with pictures and comments. I might receive a json request such as { 'type': 'Bike', 'color': 'Red', 'commentIds': [3193,3194] 'attachmentIds': [123,413] } My idea was to have a Service_LineItem_Bike class that knows how to take the json data and store an entity for a bike. My question is, the Service_LineItem class now needs to fetch comments and file attachments, and store the relationships. Service_LineItem seems like it should interact with a Service_Comment and a Service_FileUpload. Should instances of these two other services be instantiated and passed to the Service_LineItem constructor,or set by getters and setters? Dependency injection seems like the right solution, allowing a service access to a 'service fetching helper' seems wrong, and this should stay at the application level. I am using Doctrine 2 as a ORM, and I can technically write a dql query inside Service_LineItem to fetch the comments and file uploads necessary for the association, but this seems like it would have a tighter coupling, rather then leaving this up to the right service object.

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  • How to choose between using a Domain Event, or letting the application layer orchestrate everything

    - by Mr Happy
    I'm setting my first steps into domain driven design, bought the blue book and all, and I find myself seeing three ways to implement a certain solution. For the record: I'm not using CQRS or Event Sourcing. Let's say a user request comes into the application service layer. The business logic for that request is (for whatever reason) separated into a method on an entity, and a method on a domain service. How should I go about calling those methods? The options I have gathered so far are: Let the application service call both methods Use method injection/double dispatch to inject the domain service into the entity, letting the entity do it's thing and then let it call the method of the domain service (or the other way around, letting the domain service call the method on the entity) Raise a domain event in the entity method, a handler of which calls the domain service. (The kind of domain events I'm talking about are: http://www.udidahan.com/2009/06/14/domain-events-salvation/) I think these are all viable, but I'm unable to choose between them. I've been thinking about this a long time and I've come to a point where I no longer see the semantic differences between the three. Do you know of some guidelines when to use what?

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  • What layer to introduce human readable error messages?

    - by MrLane
    One of the things that I have never been happy with on any project I have worked on over the years and have really not been able to resolve myself is exactly at what tier in an application should human readable error information be retrieved for display to a user. A common approach that has worked well has been to return strongly typed/concrete "result objects" from the methods on the public surface of the business tier/API. A method on the interface may be: public ClearUserAccountsResult ClearUserAccounts(ClearUserAccountsParam param); And the result class implementation: public class ClearUserAccountsResult : IResult { public readonly List<Account> ClearedAccounts{get; set;} public readonly bool Success {get; set;} // Implements IResult public readonly string Message{get; set;} // Implements IResult, human readable // Constructor implemented here to set readonly properties... } This works great when the API needs to be exposed over WCF as the result object can be serialized. Again this is only done on the public surface of the API/business tier. The error message can also be looked up from the database, which means it can be changed and localized. However, it has always been suspect to me, this idea of returning human readable information from the business tier like this, partly because what constitutes the public surface of the API may change over time...and it may be the case that the API will need to be reused by other API components in the future that do not need the human readable string messages (and looking them up from a database would be an expensive waste). I am thinking a better approach is to keep the business objects free from such result objects and keep them simple and then retrieve human readable error strings somewhere closer to the UI layer or only in the UI itself, but I have two problems here: 1) The UI may be a remote client (Winforms/WPF/Silverlight) or an ASP.NET web application hosted on another server. In these cases the UI will have to fetch the error strings from the server. 2) Often there are multiple legitimate modes of failure. If the business tier becomes so vague and generic in the way it returns errors there may not be enough information exposed publicly to tell what the error actually was: i.e: if a method has 3 modes of legitimate failure but returns a boolean to indicate failure, you cannot work out what the appropriate message to display to the user should be. I have thought about using failure enums as a substitute, they can indicate a specific error that can be tested for and coded against. This is sometimes useful within the business tier itself as a way of passing via method returns the specifics of a failure rather than just a boolean, but it is not so good for serialization scenarios. Is there a well worn pattern for this? What do people think? Thanks.

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  • Openlayers - Redraw() layer. Add / Remove layer.

    - by Ozaki
    TLDR: I have an Openlayers map with a layer called 'track' I want to remove track and add track back in. I have an image 'imageFeature' on a layer that rotates on load to the direction being set. I want it to update this rotation that is set in 'styleMap' on a layer called 'tracking'. I set the var 'stylemap' to apply the external image & rotation. The 'imageFeature' is added to the layer at the coords specified. 'imageFeature' is removed. 'imageFeature' is added again in its new location. Rotation is not applied.. As the 'styleMap' applies to the layer I think that I have to remove the layer and add it again rather than just the 'imageFeature' Layer: var tracking = new OpenLayers.Layer.GML("Tracking", "coordinates.json", { format: OpenLayers.Format.GeoJSON, styleMap: styleMap }); styleMap: var styleMap = new OpenLayers.StyleMap({ fillOpacity: 1, pointRadius: 10, rotation: heading, }); Now wrapped in a timed function the imageFeature: map.layers[3].addFeatures(new OpenLayers.Feature.Vector( new OpenLayers.Geometry.Point(longitude, latitude), {rotation: heading, type: parseInt(Math.random() * 3)} )); Type refers to a lookup of 1 of 3 images.: styleMap.addUniqueValueRules("default", "type", lookup); var lookup = { 0: {externalGraphic: "Image1.png", rotation: heading}, 1: {externalGraphic: "Image2.png", rotation: heading}, 2: {externalGraphic: "Image3.png", rotation: heading} } I have tried the 'redraw()' function: but it returns "tracking is undefined" or "map.layers[2]" is undefined. tracking.redraw(true); map.layers[2].redraw(true); Heading is a variable: from a JSON feed. var heading = 13.542; But so far can't get anything to work it will only rotate the image onload. The image will move in coordinates as it should though. So what am I doing wrong with the redraw function or how can I get this image to rotate live? Thanks in advance -Ozaki Add: I managed to get map.layers[2].redraw(true); to sucessfully redraw layer 2. But it still does not update the rotation. I am thinking because the stylemap is updating. But it runs through the style map every n sec, but no updates to rotation and the variable for heading is updating correctly if i put a watch on it in firebug.

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  • Which layer should create DataContext?

    - by Kevin
    I have a problem to decide which layer in my system should create DataContext. I have read a book, saying that if do not pass the same DataContext object for all the database updates, it will sometimes get an exception thrown from the DataContext. That's why i initially create new instance of DataContext in business layer, and pass it into data access layer. So that the same datacontext is used for all the updates. But this lead to one design problem, if i wanna change my DAL to Non-LinqToSQL in future, i need to re-write the code in business layer as well. Please give me some advice on this. Thanks. Example code 'Business Layer Public Sub SaveData(name As String) Using ts AS New TransactionScope() Using db As New MyDataContext() DAL.Insert(db,name) DAL.Insert(db,name) End Using ts.Complete() End Using End Sub 'Data Access Layer Public Sub Insert(db as MyDataContext,name As string) db.TableAInsert(name) End Sub

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  • MVC Client Validation from Service Layer

    - by GibboK
    I'm following this article http://www.asp.net/mvc/tutorials/older-versions/models-(data)/validating-with-a-service-layer-cs to include a Service Layer with Business Logic in my MVC Web Application. I'm able to pass messages from the Service Layer to the View Model in a Html.ValidationSummary using ModelState Class. I perform basic validation logic on the View Model (using DataAnnotation attributes) and I have ClientValidation enabled by default which displaying the error message on every single field of my form. The Business logic error message which come from the Service Layer are being displayed on Html.ValidationSummary only after Posting the form to the Server. After Validation from the Service Layer I would like highlight one or more fields and have the message from the Service Layer showing on these fields instead that the Html.ValidationSummary. Any idea how to do it? Thanks

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  • Service Layer Patter - Could we avoid the service layer on a specific case?

    - by lidermin
    Hi, we are trying to implement an application using the Service Layer Pattern cause our application needs to connect to other multiple applications too, and googling on the web, we found this link of a demostrative graphic for the "right" way of apply the pattern: martinfowler.com - Service Layer Pattern But now we have a question: what if our system needs to implement some business logic, only for our application (like some maintenance data for the system itself) that we don't need to share with other systems. Based on this graphic: As it seems, it will be unnecesary to implement a service layer just for that; it will be more practical to avoid the service layer, and just go from User Interface to the Business Layer (for example). What should be the right way in this case to implement the Service Layer Pattern? What do you suggest us for a scenario like the one I told you? Thanks in advance.

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  • Service Layer Patter - Could we avoid the service layer on a specific case?

    - by lidermin
    Hi, we are trying to implement an application using the Service Layer Pattern cause our application needs to connect to other multiple applications too, and googling on the web, we found this link of a demostrative graphic for the "right" way of apply the pattern: martinfowler.com - Service Layer Pattern But now we have a question: what if our system needs to implement some business logic, only for our application (like some maintenance data for the system itself) that we don't need to share with other systems. Based on this graphic: As it seems, it will be unnecesary to implement a service layer just for that; it will be more practical to avoid the service layer, and just go from User Interface to the Business Layer (for example). What should be the right way in this case to implement the Service Layer Pattern? What do you suggest us for a scenario like the one I told you? Thanks in advance.

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  • What is the suggested way to show exception messages on UI which were produced in Business Layer?

    - by burak ozdogan
    Hi, Is there a pattern OR 'a best practice' on creating user's friendly messages in the presentation layer by using exceptions which were thrown from the Business Layer? Actually in many cases I prefer to throw Application Exceptions and this is forcing me to catch them on UI (aspx.cs pages). And if the process is complex which may produce many different types of exceptions I have to have many catch blocks to produce specific error messages. Is there a better way coming to your mind? A pattern maybe for similar cases? thanks

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