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• Integrating with a payment provider; Proper and robust OOP approach

  - by ExternalUse

  History We are currently using a so called redirect model for our online payments (where you send the payer to a payment gateway, where he inputs his payment details - the gateway will then return him to a success/failure callback page). That's easy and straight-forward, but unfortunately quite inconvenient and at times confusing for our customers (leaving the site, changing their credit card details with an additional login on another site etc). Intention & Problem description We are now intending to switch to an integrated approach using an exchange of XML requests and responses. My problem is on how to cater with all (or rather most) of the things that may happen during processing - bearing in mind that normally simplicity is robust whereas complexity is fragile. Examples User abort: The user inputs Credit Card details and hits submit. An XML message to the provider's gateway is sent and waiting for response. The user hits "stop" in his browser or closes the window. ignore_user_abort() in PHP may be an option - but is that reliable? might it be better to redirect the user to a "please wait"-page, that in turn opens an AJAX or other request to the actual processor that does not rely on the connection? Database goes away sounds over-complicated, but with e.g. a webserver in the States and a DB in the UK, it has happened and will happen again: User clicks together his order, payment request has been sent to the provider but the response cannot be stored in the database. What approach could I use, using PHP to sort of start an SQL like "Transaction" that only at the very end gets committed or rolled back, depending on the individual steps? Should then neither commit or roll back have happened, I could sort of "lock" the user to prevent him from paying again or to improperly account for payments - but how? And what else do I need to consider technically? None of the integration examples of e.g. Worldpay, Realex or SagePay offer any insight, and neither Google or my search terms were good enough to find somebody else's thoughts on this. Thank you very much for any insight on how you would approach this!

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• Should single purpose utility app use a class

  - by jmoreno

  When writing a small utility app, that does just one thing, should that one thing be encapsulated in a seperate class, or just let it be part of whatever class/module is used to start the application? I.e. Main would consist of 2 or three lines calling the constructor and then the DoIt methods, nothing else. Or should Main be the DoIt method, with whatever functions it needs added to the main class? Asking because I want to get some alternative perspective, but couldn't find a similar question. If my google-fu is bad and there's a dup, please close.

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• Do you have a data roadmap?

  - by BuckWoody

  I often visit companies where they asked me “What is SQL Server’s Roadmap?” What they mean is that they want to know where Microsoft is going with our database products. I explain that we’re expanding not only the capacities in SQL Server but the capabilities – we’re trying to make an “information platform”, rather than just a data store. But it’s interesting when I ask the same question back. “What is your data roadmap?” Most folks are surprised by the question, thinking only about storage and archival. To them, data is data. Ah, not so. Your data is one of the most valuable, if not the most valuable asset in your organization. And you should be thinking about how you’ll acquire it, how it will be distributed, how you’ll archive it (which includes more than just backing it up) and most importantly, how you’ll leverage it. Because it’s only when data becomes information that it is truly useful. to be sure, the folks on the web that collect lots of data have a strategy for it – do you? Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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• Is the Observer pattern adequate for this kind of scenario?

  - by Omega

  I'm creating a simple game development framework with Ruby. There is a node system. A node is a game entity, and it has position. It can have children nodes (and one parent node). Children are always drawn relatively to their parent. Nodes have a @position field. Anyone can modify it. When such position is modified, the node must update its children accordingly to properly draw them relatively to it. @position contains a Point instance (a class with x and y properties, plus some other useful methods). I need to know when a node's @position's state changes, so I can tell the node to update its children. This is easy if the programmer does something like this: @node.position = Point.new(300,300) Because it is equivalent to calling this: # Code in the Node class def position=(newValue) @position = newValue update_my_children # <--- I know that the position changed end But, I'm lost when this happens: @node.position.x = 300 The only one that knows that the position changed is the Point instance stored in the @position property of the node. But I need the node to be notified! It was at this point that I considered the Observer pattern. Basically, Point is now observable. When a node's position property is given a new Point instance (through the assignment operator), it will stop observing the previous Point it had (if any), and start observing the new one. When a Point instance gets a state change, all observers (the node owning it) will be notified, so now my node can update its children when the position changes. A problem is when this happens: @someNode.position = @anotherNode.position This means that two nodes are observing the same point. If I change one of the node's position, the other would change as well. To fix this, when a position is assigned, I plan to create a new Point instance, copy the passed argument's x and y, and store my newly created point instead of storing the passed one. Another problem I fear is this: somePoint = @node.position somePoint.x = 500 This would, technically, modify @node's position. I'm not sure if anyone would be expecting that behavior. I'm under the impression that people see Point as some kind of primitive rather than an actual object. Is this approach even reasonable? Reasons I'm feeling skeptical: I've heard that the Observer pattern should be used with, well, many observers. Technically, in this scenario there is only one observer at a time. When assigning a node's position as another's (@someNode.position = @anotherNode.position), where I create a whole new instance rather than storing the passed point, it feels hackish, or even inefficient.

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• OOP PHP make separate classes or one

  - by user2956219

  I'm studying OOP PHP and working on a small personal project but I have hard time grasping some concepts. Let's say I have a list of items, each item belongs to subcategory, and each subcategory belongs to category. So should I make separate classes for category (with methods to list all categories, add new category, delete category), class for subcategories and class for items? Or should I make creating, listing and deleting categories as methods for item class? Both category and subcategory are very simple and basically consist of ID, Name and parentID (for subcategory).

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• How to implement string matching based on a pattern

  - by Vincent Rischmann

  I was asked to build a tool that can identify if a string match a pattern. Example: {1:20} stuff t(x) {a,b,c} would match: 1 stuff tx a 20 stuff t c It is a sort of regex but with a different syntax Parentheses indicate an optional value {1:20} is a interval; I will have to check if the token is a number and if it is between 1 and 20 {a,b,c} is just an enumeration; it can be either a or b or c Right now I implemented this with a regex, and the interval stuff was a pain to do. On my own time I tried implementing some kind of matcher by hand, but it turns out it's not that easy to do. By experimenting I ended up with a function that generates a state table from the pattern and a state machine. It worked well until I tried to implement the optional value, and I got stuck and how to generate the state table. After that I searched how I could do this, and that led me to stuff like LL parser, LALR parser, recursive-descent parser, context-free grammars, etc. I never studied any of this so it's hard to know what is relevant here, but I think this is what I need: A grammar A parser which generates states from the grammar and a pattern A state machine to see if a string match the states So my first question is: Is this right ? And second question, what do you recommend I read/study to be able to implement this ?

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• Charakter coding / programming

  - by Jery

  lately I tryed a few times to create charakters for some games, but at some certain point (especially when collision detection came in) everything became messy and the interaction between chars, the world and certain items had a lot of bugs. So here is my question, how do you ussualy keep track of actions that your charakter is allowed to do, or more in general do you have some links / advices how to set up a char efficiantly? I´m working on a char right now, who should at least be able to run, jump, pick items up and use different fighting animations. Most ideas I came up with until now use some kind of action.priority / action.duration system to determain whats possible and what not, or a "action-manager" which defines for every action what is possible from that action on but it all doesnt work that well together =\ thx in advance for some input

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• Settings object with singleton pattern

  - by axis

  I need to build an object that will have only one instance because this Object is dedicated to the storage of vital settings for my application and I would like to avoid a misuse of this type or a conflict at run-time. The most popular solution for this, according to the internet, is the Singleton pattern. But I would like to know about other ideas or solutions for this; also I would like to know if other solutions can be much more easy to grasp for an user of this hypothetical library. Thanks.

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• share code between check and process methods

  - by undu

  My job is to refactor an old library for GIS vector data processing. The main class encapsulates a collection of building outlines, and offers different methods for checking data consistency. Those checking functions have an optional parameter that allows to perform some process. For instance: std::vector<Point> checkIntersections(int process_mode = 0); This method tests if some building outlines are intersecting, and return the intersection points. But if you pass a non null argument, the method will modify the outlines to remove the intersection. I think it's pretty bad (at call site, a reader not familiar with the code base will assume that a method called checkSomething only performs a check and doesn't modifiy data) and I want to change this. I also want to avoid code duplication as check and process methods are mostly similar. So I was thinking to something like this: // a private worker std::vector<Point> workerIntersections(int process_mode = 0) { // it's the equivalent of the current checkIntersections, it may perform // a process depending on process_mode } // public interfaces for check and process std::vector<Point> checkIntersections() /* const */ { workerIntersections(0); } std::vector<Point> processIntersections(int process_mode /*I have different process modes*/) { workerIntersections(process_mode); } But that forces me to break const correctness as workerIntersections is a non-const method. How can I separate check and process, avoiding code duplication and keeping const-correctness?

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• Is there a pattern to restrict which classes can update another class?

  - by Mike

  Say I have a class ImportantInfo with a public writable property Data. Many classes will read this property but only a few will ever set it. Basically, if you want to update Data you should really know what you're doing. Is there a pattern I could use to make this explicit other than by documenting it? For example, some way to enforce that only classes that implement IUpdateImportantData can do it (this is just an example)? I'm not talking about security here, but more of a "hey, are you sure you want to do that?" kind of thing.

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• C#.NET: How to update multiple .NET pages when a particular event occurs in one .Net page? In another words how to use Observer pattern(Publish and subscribe to events)

  Problem: Suppose you have a scenario in which you have to update multiple pages when an event occurs in main page. For example imagine you have a main page where you are dispalying a tab control. This tab control has 3 tab pages where you are loading 3 different user controls. On click of an update button in main page imagine if you have do something in all the 3 tab panels. In other words an event in main page has to be handled in many other pages. An event in main page which contains the tab control has to be handled in all the tab panels(user controls) Answer: Use Observer pattern Define a base page for the page that contains the tab control. Main page which contains the tab: Baseline_Baseline Basepage for the above main page: BaselineBasePage User control that has to be udpated for an event in main page: Baseline_PriorNonDeloitte Source Code: public class BaselineBasePage : System.Web.UI.Page { IList lstControls = new List(); public void Add(IObserver userControl) { lstControls.Add(userControl); } public void Remove(IObserver userControl) { lstControls.Remove(userControl); } public void RemoveAllUserControls() { lstControls.Clear(); } public void Update(SaveEventArgs e) { foreach (IObserver LobjControl in lstControls) { LobjControl.Save(e); } } } public interface IObserver { void Update(SaveEventArgs e); } public partial class Baseline_Baseline : BaselineBasePage { . . . this.Add(_ucPI); this.Add(_ucPI1); protected void abActionBar_saveClicked(object sender, EventArgs e) { SaveEventArgs se = new SaveEventArgs(); se.TabType = (BaselineTabType)tcBaseline.ActiveTabIndex; this.Update(se); } } Public class Baseline_PriorNonDeloitte : System.Web.UI.UserControl,IObserver { public void Update(SaveEventArgs e) { } } More info at: http://www.dofactory.com/Patterns/PatternObserver.aspx span.fullpost {display:none;}

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• When you’re on a high, start something big

  - by BuckWoody

  Most days are pretty average – we have some highs, some lows, and just regular old work to do. But some days the sun is shining, your co-workers are especially nice, and everything just falls into place. You really *enjoy* what you do. Don’t let that moment pass. All of us have “big” projects that we need to tackle. Things that are going to take a long time, and a lot of money. Those kinds of data projects take a LOT of planning, and many times we put that off just to get to the day’s work. I’ve found that the “high” moments are the perfect time to take on these big projects. I’m more focused, and more importantly, more positive. And as the quote goes, “whether you think you can or you think you can’t, you’re probably right.” You’ll find a way to make it happen if you’re in a positive mood. Now – having those “great days” is actually something you can influence, but I’ll save that topic for a future post. I have a project to work on. :) Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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• Calculate Quantity Available for POS - Inventory [closed]

  - by tunmise fasipe

  From what I have read Quantity on Hand is the physical number of Items in stock http://www.businessdictionary.com/definition/quantity-on-hand.html Quantity Available is Quantity On Hand minus outbound items (e.g Ordered Quantity) http://community.intuit.com/posts/quantity-on-hand-vs-quantity-available-2 Does this still hold for POS? Can there be outbound items in POS system since items are picked up immediately? If not does that mean QtyOnHand = QtyAvailable for POS?

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• "Collection Wrapper" pattern - is this common?

  - by Prog

  A different question of mine had to do with encapsulating member data structures inside classes. In order to understand this question better please read that question and look at the approach discussed. One of the guys who answered that question said that the approach is good, but if I understood him correctly - he said that there should be a class existing just for the purpose of wrapping the collection, instead of an ordinary class offering a number of public methods just to access the member collection. For example, instead of this: class SomeClass{ // downright exposing the concrete collection. Things[] someCollection; // other stuff omitted Thing[] getCollection(){return someCollection;} } Or this: class SomeClass{ // encapsulating the collection, but inflating the class' public interface. Thing[] someCollection; // class functionality omitted. public Thing getThing(int index){ return someCollection[index]; } public int getSize(){ return someCollection.length; } public void setThing(int index, Thing thing){ someCollection[index] = thing; } public void removeThing(int index){ someCollection[index] = null; } } We'll have this: // encapsulating the collection - in a different class, dedicated to this. class SomeClass{ CollectionWrapper someCollection; CollectionWrapper getCollection(){return someCollection;} } class CollectionWrapper{ Thing[] someCollection; public Thing getThing(int index){ return someCollection[index]; } public int getSize(){ return someCollection.length; } public void setThing(int index, Thing thing){ someCollection[index] = thing; } public void removeThing(int index){ someCollection[index] = null; } } This way, the inner data structure in SomeClass can change without affecting client code, and without forcing SomeClass to offer a lot of public methods just to access the inner collection. CollectionWrapper does this instead. E.g. if the collection changes from an array to a List, the internal implementation of CollectionWrapper changes, but client code stays the same. Also, the CollectionWrapper can hide certain things from the client code - from example, it can disallow mutation to the collection by not having the methods setThing and removeThing. This approach to decoupling client code from the concrete data structure seems IMHO pretty good. Is this approach common? What are it's downfalls? Is this used in practice?

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• Do open world games need less backstory?

  - by Raceimaztion

  I've played a few open-world games and really enjoyed them, though the ones I've really enjoyed have generally received complaints about how little story there is to them. The Saboteur is one example of this. Fully open-world, good enough story (for me, anyway), engaging gameplay, and still has received complaints in reviews about not having enough story. Do open-world games actually need a full, all-encompassing story? Or can fun and engaging gameplay fill in the gap and let the designer get away with a slightly less complete story?

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• Connect divs with (non-straight) lines [migrated]

  - by Snailer

  I'd like to develop my site with a layout that looks somewhat like houses with connected plumbing, or multiple computers connected to a network. Basically, the will be boxes floating in space, with lines connecting some of the boxes. I'd like these lines to have some turns in them as well (just simple 90 degree corners) rather than just a straight line. My question is what is the best way to achieve this, and perhaps a small example. My thoughts were to use: PHP and CSS: I could create a background grid and then, with some complicated algorithms, draw paths using the grid's borders. This would be more dynamic, but I'm not sure I can plot the math all by myself. just CSS: Perhaps this is as simple as making some pre-drawn lines like L-shapes and T-junctions, then just placing and scaling them. But I don't believe there's a way to scale an image by slicing it.. so the line width would be scaled and thus each image would look different. Any thoughts?

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• What's wrong with this answer? [migrated]

  - by MikeLJ

  I wrote an answer to this question, but I can't post it even though it's not opinion based. which tile size to choice for 16-bits What's wrong with my answer? The Answer: I'll use these classic 16-bit consoles as reference: http://en.wikipedia.org/wiki/History_of_video_game_consoles_(fourth_generation) Super Nintendo: Max Resolution: 512x478 Sprites On Screen: 128 Max Sprite Size: 8×8. TurboGrafx-16: Max Resolution: 565x242 "Normal" resolution: 256×239 Sprites On Screen: 64 Max Sprite Sizes: 32×64 Neo Geo: Display resolution: 320×224 "Normal" Resolution: 304x224 Sprites on screen: 380 Max Sprite Size: 16x512

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• Synthetic database records

  - by michipili

  Assume we are getting some statistics from a customer which we analyse and we send our comments to the customer. Now, the customer tells us that the statistic they computed between January and March are based on a wrong methodology and sends us corrected series. We want perform analysis with the wrong and with the correct set of data, which are huge and only differ from January to March. Therefore, we need something like synthetic database records implementing the following logic: synthetic[1] = wrong_data synthetic[2] = correct_data between Januar and March, wrong_data otherwise With this, we can easily perform our analyses on synthetic records. Should such synthetic records be implemented in the application logic or on the side of the database? What are common pitfalls of such an implementation?

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• How does process of updating code with Continous Integration work?

  - by BleakCabalist

  I want to draw a model of process of updating the source code with the use of Continous Integration. The main issue is I don't really understand how it works when there are several programmers working on various aspects of the code at the same time. I can't visualize it in my mind. Here's what I know but I might be wrong: New code is sent to repository. Continous Integration server asks Version Control System if there is a new code in repository. If there is than CIS executes tests on the code. If tests show there are problems than CIS orders VCS to revert back to working wersion of the code and communicates it to programmer. If tests are passed positively it compiles the repository code and makes new build of a game? New build is made not after ever single change, but at the end of the day I believe? Are my assumptions above correct? If yes, does it also work when there are several programmers updating repository at once? Is this enough to draw a model of the process in your opinions or did I miss something? Also, what software would I need for above process? Can you guys give examples for CIS software and VCS software and whatever else I need? Does CIS software perform code tests or do I need another tool for that and integrate it with CIS? Is there a repository software?

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• Managing different utility classes between engine and libraries

  - by hayer

  I'm currently in updating some engine code (which does not work, so it is more like creating a engine). I've decided to swap over to SFML (instead of my own crappy renderer, window manager, and audio), Box2D (since I need physics, but have none), and some small utilities I've built myself. The problem is that each of the project mentioned over use different types for things like Vector2, etc. So to the question: is it a good idea to replace Box2D and SFML vectors with my own vector class (which is one of my better implementations)? My idea then was to have a separate .lib with all my classes that should be shared between all the projects in the solution.

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• Content of AUTHORS file

  - by user14284

  GNU recommend make AUTHORS file for list of authors and contributos of a program. But how many "levels" of authors and contributors should contain the file? E.g. I write a program foo, that actively use some library. Should I include authors of the library in the AUTHORS? It seems to yes, because total code of foo contain code from library. But if yes, I should include also authors of all others libraries, including standard libraries of compiler, authors of the compiler and other tools for producing final executable code, authors of OS... When I should stop?

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• How can I refactor my code to use fewer singletons?

  - by fish

  I started a component based, networked game (so far only working on the server). I know why singletons can be bad, but I can't think of another way to implement the same thing. So far I have: A GameState singleton (for managing the global state of the game, i.e. pre-game, running, exiting). A World singleton, which is the root entity for my entity graph An EntityFactory A ComponentFactory I'm thinking about adding a "MessageDispatcher" so individual components can subscribe to network messages. The factories do not have state, so I suppose they aren't so bad. However, the others do have global state, which is asking for trouble. How can I refactor my code so it uses fewer singletons?

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• Architecture or Pattern for handling properties with custom setter/getter?

  - by Shelby115

  Current Situation: I'm doing a simple MVC site for keeping journals as a personal project. My concern is I'm trying to keep the interaction between the pages and the classes simplistic. Where I run into issues is the password field. My setter encrypts the password, so the getter retrieves the encrypted password. public class JournalBook { private IEncryptor _encryptor { get; set; } private String _password { get; set; } public Int32 id { get; set; } public String name { get; set; } public String description { get; set; } public String password { get { return this._password; } set { this.setPassword(this._password, value, value); } } public List<Journal> journals { get; set; } public DateTime created { get; set; } public DateTime lastModified { get; set; } public Boolean passwordProtected { get { return this.password != null && this.password != String.Empty; } } ... } I'm currently using model-binding to submit changes or create new JournalBooks (like below). The problem arises that in the code below book.password is always null, I'm pretty sure this is because of the custom setter. [HttpPost] public ActionResult Create(JournalBook book) { // Create the JournalBook if not null. if (book != null) this.JournalBooks.Add(book); return RedirectToAction("Index"); } Question(s): Should I be handling this not in the property's getter/setter? Is there a pattern or architecture that allows for model-binding or another simple method when properties need to have custom getters/setters to manipulate the data? To summarize, how can I handle the password storing with encryption such that I have the following, Robust architecture I don't store the password as plaintext. Submitting a new or modified JournalBook is as easy as default model-binding (or close to it).

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• Creating a Predicate Builder extension method

  - by Rippo

  I have a Kendo UI Grid that I am currently allowing filtering on multiple columns. I am wondering if there is a an alternative approach removing the outer switch statement? Basically I want to able to create an extension method so I can filter on a IQueryable<T> and I want to drop the outer case statement so I don't have to switch column names. private static IQueryable<Contact> FilterContactList(FilterDescriptor filter, IQueryable<Contact> contactList) { switch (filter.Member) { case "Name": switch (filter.Operator) { case FilterOperator.StartsWith: contactList = contactList.Where(w => w.Firstname.StartsWith(filter.Value.ToString()) || w.Lastname.StartsWith(filter.Value.ToString()) || (w.Firstname + " " + w.Lastname).StartsWith(filter.Value.ToString())); break; case FilterOperator.Contains: contactList = contactList.Where(w => w.Firstname.Contains(filter.Value.ToString()) || w.Lastname.Contains(filter.Value.ToString()) || (w.Firstname + " " + w.Lastname).Contains( filter.Value.ToString())); break; case FilterOperator.IsEqualTo: contactList = contactList.Where(w => w.Firstname == filter.Value.ToString() || w.Lastname == filter.Value.ToString() || (w.Firstname + " " + w.Lastname) == filter.Value.ToString()); break; } break; case "Company": switch (filter.Operator) { case FilterOperator.StartsWith: contactList = contactList.Where(w => w.Company.StartsWith(filter.Value.ToString())); break; case FilterOperator.Contains: contactList = contactList.Where(w => w.Company.Contains(filter.Value.ToString())); break; case FilterOperator.IsEqualTo: contactList = contactList.Where(w => w.Company == filter.Value.ToString()); break; } break; } return contactList; } Some additional information, I am using NHibernate Linq. Also another problem is that the "Name" column on my grid is actually "Firstname" + " " + "LastName" on my contact entity. We can also assume that all filterable columns will be strings.

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• Should Business Interfaces be part of the Model layer?

  - by Mik378

  In an oriented-services enterprise application, isn't it an antipattern to mix Service APIs (containing interface that external users depends on) with Model objects (entities, custom exceptions objects etc...) ? According to me, Services should only depends on Model layer but never mixed with it. In fact, my colleague told me that it doesn't make sense to separate it since client need both. (model and service interfaces) But I notice that everytime a client asks for some changes, like adding a new method in some interface (means a new service), Model layer has to be also delivered... Thus, client who has not interested by this "addition" is constrained to be concerned by this update of Model... and in a large enterprise application, this kind of delivery is known to be very risked... What is the best practice ? Separate services(only interfaces so) and model objects or mix it ?

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