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• Large invoice database structure and rendering

  - by user132624

  Our client has a MS SQL database that has 1 million customer invoice records in it. Using the database, our client wants its customers to be able to log into a frontend web site and then be able to view, modify and download their company’s invoices. Given the size of the database and the large number of customers who may log into the web site at any time, we are concerned about data base engine performance and web page invoice rendering performance. The 1 million invoice database is for just 90 days sales, so we will remove invoices over 90 days old from the database. Most of the invoices have multiple line items. We can easily convert our invoices into various data formats so for example it is easy for us to convert to and from SQL to XML with related schema and XSLT. Any data conversion would be done on another server so as not to burden the web interface server. We have tentatively decided to run the web site on a .NET Framework IIS web server using MS SQL on MS Azure. How would you suggest we structure our database for best performance? For example, should we put all the invoices of all customers located within the same 5 digit or 6 digit zip codes into the same table? Or could we set up a separate home directory for each customer on IIS and place each customer’s invoices in each customer’s home directory in XML format? And secondly what would you suggest would be the best method to render customer invoices on a web page and allow customers to modify for best performance? The ADO.net XML Data Set looks intriguing to us as a method, but we have never used it.

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• Music Notation Editor - Refactoring view creation logic elsewhere

  - by Cyril Silverman

  Let me preface by saying that knowing some elementary music theory and music notation may be helpful in grasping the problem at hand. I'm currently building a Music Notation and Tablature Editor (in Javascript). But I've come to a point where the core parts of the program are more or less there. All functionality I plan to add at this point will really build off the foundation that I've created. As a result, I want to refactor to really solidify my code. I'm using an API called VexFlow to render notation. Basically I pass the parts of the editor's state to VexFlow to build the graphical representation of the score. Here is a rough and stripped down UML diagram showing you the outline of my program: In essence, a Part has many Measures which has many Notes which has many NoteItems (yes, this is semantically weird, as a chord is represented as a Note with multiple NoteItems, individual pitches or fret positions). All of the relationships are bi-directional. There are a few problems with my design because my Measure class contains the majority of the entire application view logic. The class holds the data about all VexFlow objects (the graphical representation of the score). It contains the graphical Staff object and the graphical notes. (Shouldn't these be placed somewhere else in the program?) While VexFlowFactory deals with actual creation (and some processing) of most of the VexFlow objects, Measure still "directs" the creation of all the objects and what order they are supposed to be created in for both the VexFlowStaff and VexFlowNotes. I'm not looking for a specific answer as you'd need a much deeper understanding of my code. Just a general direction to go in. Here's a thought I had, create an MeasureView/NoteView/PartView classes that contains the basic VexFlow objects for each class in addition to any extraneous logic for it's creation? but where would these views be contained? Do I create a ScoreView that is a parallel graphical representation of everything? So that ScoreView.render() would cascade down PartView and call render for each PartView and casade down into each MeasureView, etc. Again, I just have no idea what direction to go in. The more I think about it, the more ways to go seem to pop into my head. I tried to be as concise and simplistic as possible while still getting my problem across. Please feel free to ask me any questions if anything is unclear. It's quite a struggle trying to dumb down a complicated problem to its core parts.

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• Where and how to reference composite MVP components?

  - by Lea Hayes

  I am learning about the MVP (Model-View-Presenter) Passive View flavour of MVC. I intend to expose events from view interfaces rather than using the observer pattern to remove explicit coupling with presenter. Context: Windows Forms / Client-Side JavaScript. I am led to believe that the MVP (or indeed MVC in general) pattern can be applied at various levels of a user interface ranging from the main "Window" to an embedded "Text Field". For instance, the model to the text field is probably just a string whereas the model to the "Window" contains application specific view state (like a persons name which resides within the contained text field). Given a more complex scenario: Documentation viewer which contains: TOC navigation pane Document view Search pane Since each of these 4 user interface items are complex and can be reused elsewhere it makes sense to design these using MVP. Given that each of these user interface items comprises of 3 components; which component should be nested? where? who instantiates them? Idea #1 - Embed View inside View from Parent View public class DocumentationViewer : Form, IDocumentationViewerView { public DocumentationViewer() { ... // Unclear as to how model and presenter are injected... TocPane = new TocPaneView(); } protected ITocPaneView TocPane { get; private set; } } Idea #2 - Embed Presenter inside View from Parent View public class DocumentationViewer : Form, IDocumentationViewerView { public DocumentationViewer() { ... // This doesn't seem like view logic... var tocPaneModel = new TocPaneModel(); var tocPaneView = new TocPaneView(); TocPane = new TocPanePresenter(tocPaneModel, tocPaneView); } protected TocPanePresenter TocPane { get; private set; } } Idea #3 - Embed View inside View from Parent Presenter public class DocumentationViewer : Form, IDocumentationViewerView { ... // Part of IDocumentationViewerView: public ITocPaneView TocPane { get; set; } } public class DocumentationViewerPresenter { public DocumentationViewerPresenter(DocumentationViewerModel model, IDocumentationViewerView view) { ... var tocPaneView = new TocPaneView(); var tocPaneModel = new TocPaneModel(model.Toc); var tocPanePresenter = new TocPanePresenter(tocPaneModel, tocPaneView); view.TocPane = tocPaneView; } } Some better idea...

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• Representation of data in application versus database

  - by user1815201

  I'm going to make an application that will be given data to put in a database. The data will for the most part be the same, but the way it is formatted will vary a lot (could be in anything from text files to .xls to .doc). I'm not a very experienced developer, but I can see some potential issues and I want to minimize them. First off I have decided to use the DAO pattern, so that I can easily support new file formats or file suddenly formatted in different ways. What I really wonder about though, is how I should manage the data itself within my application. I'm thinking that the database DAO should have models representing each table of the database with the same relations between them, to make the uploading process easy. But should the filesystem DAO's have to use the same models? I can imaging that when the database changes, the change will suddenly propagate throughout the entire system, all DAOs and models alike. And that is obviously a bad thing. I'm a little bit tired and out of time. Will update with what ever questions you have. Thanks!

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• Game timings and formats

  - by topright

  There are more or less standardized TV-show/movie formats and recommended timings: 1. By the early 1960s, television companies commonly presented half-hour long "comedy" series, or one hour long "dramas." Half-hour series were mostly restricted to situation comedy or family comedy, and were usually aired with either a live or artificial laugh track. One hour dramas included genre series such as police and detective series, westerns, science fiction, and, later, serialized prime time soap operas. Programs today still overwhelmingly conform to these half-hour and one hour guidelines. Source 2. In the United States, most medical dramas are one hour long. Source 3. Traditionally serials were broadcast as fifteen minute installments each weekday in daytime slots. In 1956 As the World Turns debuted as the first half-hour soap opera. All soap operas broadcast half-hour episodes by the end of the 1960s. With increased popularity in the 1970s most soap operas expanded to an hour (Another World even expanded to ninety minutes for a short time). More than half of the serials had expanded to one hour episodes by 1980. As of 2010, six of the seven US serials air one hour episodes each weekday. Source Interesting. Are there any standards of timing in game development? Well, 5-20 minutes casual games, of course. There is even a "5-minutes-game" site. And 1-hour-gamer site. Are there 1-week, 1-year, 1-eternity game formats? Chess and Go - deep games that you can study all your life; but they are played in hour or several days (pro games). Addictive long-term online role-playing games (without win-condition) are played in monthes and, possibly, years. Replayability is an important factor to consider. It's good when game design document contains a line: "A game is designed for solving in X hours". How can it be measured before there is any prototype or demo? When you know your game format, you know your audience (and vice versa). It is practical question. Are there psychological researches about dynamic of gaming interest and involvement? And is there a correlation between game format and game genre?

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• Database Schema Usage

  - by CrazyHorse

  I have a question regarding the appropriate use of SQL Server database schemas and was hoping that some database gurus might be able to offer some guidance around best practice. Just to give a bit of background, my team has recently shrunk to 2 people and we have just been merged with another 6 person team. My team had set up a SQL Server environment running off a desktop backing up to another desktop (and nightly to the network), whilst the new team has a formal SQL Server environment, running on a dedicated server, with backups and maintenance all handled by a dedicated team. So far it's good news for my team. Now to the query. My team designed all our tables to belong to a 3-letter schema name (e.g. User = USR, General = GEN, Account = ACC) which broadly speaking relate to specific applications, although there is a lot of overlap. My new team has come from an Access background and have implemented their tables within dbo with a 3-letter perfix followed by "_tbl" so the examples above would be dbo.USR_tblTableName, dbo.GEN_tblTableName and dbo.ACC_tblTableName. Further to this, neither my old team nor my new team has gone live with their SQL Servers yet (we're both coincidentally migrating away from Access environments) and the new team have said they're willing to consider adopting our approach if we can explain how this would be beneficial. We are not anticipating handling table updates at schema level, as we will be using application-level logins. Also, with regards to the unwieldiness of the 7-character prefix, I'm not overly concerned myself as we're using LINQ almost exclusively so the tables can simply be renamed in the DMBL (although I know that presents some challenges when we update the DBML). So therefore, given that both teams need to be aligned with one another, can anyone offer any convincing arguments either way?

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• Questions re: Eclipse Jobs API

  - by BenCole

  Similar to http://stackoverflow.com/questions/8738160/eclipse-jobs-api-for-a-stand-alone-swing-project This question mentions the Jobs API from the Eclipse IDE: ...The disadvantage of the pre-3.0 approach was that the user had to wait until an operation completed before the UI became responsive again. The UI still provided the user the ability to cancel the currently running operation but no other work could be done until the operation completed. Some operations were performed in the background (resource decoration and JDT file indexing are two such examples) but these operations were restricted in the sense that they could not modify the workspace. If a background operation did try to modify the workspace, the UI thread would be blocked if the user explicitly performed an operation that modified the workspace and, even worse, the user would not be able to cancel the operation. A further complication with concurrency was that the interaction between the independent locking mechanisms of different plug-ins often resulted in deadlock situations. Because of the independent nature of the locks, there was no way for Eclipse to recover from the deadlock, which forced users to kill the application... ...The functionality provided by the workspace locking mechanism can be broken down into the following three aspects: Resource locking to ensure multiple operations did not concurrently modify the same resource Resource change batching to ensure UI stability during an operation Identification of an appropriate time to perform incremental building With the introduction of the Jobs API, these areas have been divided into separate mechanisms and a few additional facilities have been added. The following list summarizes the facilities added. Job class: support for performing operations or other work in the background. ISchedulingRule interface: support for determining which jobs can run concurrently. WorkspaceJob and two IWorkspace#run() methods: support for batching of delta change notifications. Background auto-build: running of incremental build at a time when no other running operations are affecting resources. ILock interface: support for deadlock detection and recovery. Job properties for configuring user feedback for jobs run in the background. The rest of this article provides examples of how to use the above-mentioned facilities... In regards to above API, is this an implementation of a particular design pattern? Which one?

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• Programming and Ubiquitous Language (DDD) in a non-English domain

  - by Sandor Drieënhuizen

  I know there are some questions already here that are closely related to this subject but none of them take Ubiquitous Language as the starting point so I think that justifies this question. For those who don't know: Ubiquitous Language is the concept of defining a (both spoken and written) language that is equally used across developers and domain experts to avoid inconsistencies and miscommunication due to translation problems and misunderstanding. You will see the same terminology show up in code, conversations between any team member, functional specs and whatnot. So, what I was wondering about is how to deal with Ubiquitous Language in non-English domains. Personally, I strongly favor writing programming code in English completely, including comments but ofcourse excluding constants and resources. However, in a non-English domain, I'm forced to make a decision either to: Write code reflecting the Ubiquitous Language in the natural language of the domain. Translate the Ubiquitous Language to English and stop communicating in the natural language of the domain. Define a table that defines how the Ubiquitous Language translates to English. Here are some of my thoughts based on these options: 1) I have a strong aversion against mixed-language code, that is coding using type/member/variable names etc. that are non-English. Most programming languages 'breathe' English to a large extent and most of the technical literature, design pattern names etc. are in English as well. Therefore, in most cases there's just no way of writing code entirely in a non-English language so you end up with mixed languages anyway. 2) This will force the domain experts to start thinking and talking in the English equivalent of the UL, something that will probably not come naturally to them and therefore hinders communication significantly. 3) In this case, the developers communicate with the domain experts in their native language while the developers communicate with each other in English and most importantly, they write code using the English translation of the UL. I'm sure I don't want to go for the first option and I think option 3 is much better than option 2. What do you think? Am I missing other options? UPDATE Today, about year later, having dealt with this issue on a daily basis, I have to say that option 3 has worked out pretty well for me. It wasn't as tedious as I initially feared and translating in real time while talking to the client wasn't a problem either. I also found the following advantages to be true, based on my experience. Translating the UL makes you pay more attention to defining the UL and even the domain itself, especially when you don't know how to translate a term and you have to start looking through dictionaries etc. This has even caused me to reconsider domain modeling decisions a few times. It helps you make your knowledge of the English language more profound. Obviously, your code is much more pleasant to look at instead of being a mind boggling obscenity.

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• Working with data and meta data that are separated on different servers

  - by afuzzyllama

  While developing a product, I've come across a situation where my group wants to store meta data for data entry forms (questions, layout, etc) in a different database then the database where the collected data is stored. This is mostly for security because we want to be able to have our meta data public facing, while keeping collected data as secure as possible. I was thinking about writing a web service that provides the meta information that the data collection program could access. The only issue I see with this approach is the front end is going to have to match the meta data with the collected data, which would be more efficient as a join on the back end. Currently, this system is slated to run on .NET and MSSQL. I haven't played around with .NET libraries running in SQL, but I'm considering trying to create logic that would pull from the web service, convert the meta data into a table that SQL can join on, and return the combined data and meta data that way. Is this solution the wrong way to approach the problem? Is there a pattern or "industry standard" way of bringing together two datasets that don't live in the same database?

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• As a web designer, which language should I learn first for my feature career? (PHP or JavaScript) [closed]

  - by kdevs3

  Possible Duplicates: Best Programming Language for Web Development How can I choose a web development language? What language will you choose if you are going to build something big? What is the right option of programming languages and tools for building our website? What is the easiest web programing language at....? Well, I'm more of a basic web designer. I know the easy stuff pretty well. (Ya know, html, css) But I've been trying to take it to the next step and I'm contemplating about what I should learn that will help me out the most in my future web design/programming career, should it be JavaScript or maybe I should try to learn a back end programming language such as PHP. Lately, I have been hearing about a lot how JavaScript is so great and useful now, because of libraries such as jQuery and what possibility's it can bring by using Node.js and other frameworks. I've only learned the most basic of JavaScript and used some jQuery (mostly plugins) so i wouldn't know at all of what it can actually do. Would JS being so popular as it is now and useful, be a reason to stick with JavaScript and only learn it that for now? Or as a web designer, how important would it be to learn how to make a web application/website operate and functional, and know how to work with servers, etc? (Such as getting forms to work and sending data to the server and back) I've took a look at frameworks such as Code Igniter before, and looks really simple to get started with if I try to learn PHP, But I'm not sure how important it is for my career and what I would gain out of it. I'm asking because I can't decide what I should learn first. When I select it, I really want to take my time and learn the language. I don't want to spend time on learning multiple languages at the same time, so I need to pick wisely. I'm trying to turn the right direction so my career can hopefully be successful in the feature. (If money/gaining a job asked if its important, then its a yeah, it is a bit) I'm hoping I can get opinions and suggestions on this question, thanks for giving me your thoughts also.

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• Javascript Implementation Patterns for Server-side MVC Websites

  - by tmo256

  I'm looking for information on common patterns for initializing and executing Javascript page by page in a "traditional" server-side MVC website architecture. A few months ago, my development team began, but abandoned, a major re-architecture of our company's primary web app, including a full front-end redesign. In the process, there was some debate about the architecture of the Javascript in the current version of the site, and whether it fit into a clear, modern design pattern. Now I've returned to the process of overhauling the front end of this and several other MVC websites (Ruby on Rails and MVC.net) to implement a responsive framework (Bootstrap), and in the process will again need to review then revamp and update a lot of Javascript. These web applications are NOT single-page Javascript applications (in fact, we are ripping out a lot of Ajax) or designed to require a Javascript MVC pattern; these apps are basically brochure, catalog and administrative sites that follow a server-side MVC pattern. The vast majority of the Javascript required is behavioral, pre-built plugins (JQuery and Bootstrap, et al) that execute on specific DOM nodes. I'm going to give a very brief (as brief as I can be) run-down of the current architecture only in order to illustrate the scope and type of paradigm I'm talking about. Hopefully, it will help you understand the nature of the patterns I'm looking for, but I'm not looking for commentary on the specifics of this code. What I've done in the past is relatively straight-forward and easy to maintain, but, as mentioned above, some of the other developers don't like the current architecture. Currently, on document ready, I execute whatever global Javascript needs to occur on every page, and then call a page-specific init function to initialize node-specific functionality, retrieving the init method from a JS object. On each page load, something like this will happen: $(document).ready(function(){ $('header').menuAction(); App.pages.executePage('home','show'); //dynamic from framework request object }); And the main App javascript is like App = { usefulGlobalVar: 0, pages: { executePage: function(action, controller) { // if exists, App.pages[action][controller].init() }, home: { show: { init: function() { $('#tabs').tabs(); //et. al }, normalizeName: function() { // dom-specific utility function that // doesn't require a full-blown component/class/module } }, edit: ... }, user_profile: ... } } Any common features and functionality requiring modularization or compotentizing is done as needed with prototyping. For common implementation of plugins, I often extend JQuery, so I can easily initialize a plugin with the same options throughout the site. For example, $('[data-tabs]').myTabs() with this code in a utility javascript file: (function($) { $.fn.myTabs = function() { this.tabs( { //...common options }); }; }) Pointers to articles, books or other discussions would be most welcome. Again, I am looking for a site-wide implementation pattern, NOT a JS MVC framework or general how-tos on creating JS classes or components. Thanks for your help!

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• Designing for an algorithm that reports progress

  - by Stefano Borini

  I have an iterative algorithm and I want to print the progress. However, I may also want it not to print any information, or to print it in a different way, or do other logic. In an object oriented language, I would perform the following solutions: Solution 1: virtual method have the algorithm class MyAlgoClass which implements the algo. The class also implements a virtual reportIteration(iterInfo) method which is empty and can be reimplemented. Subclass the MyAlgoClass and override reportIteration so that it does what it needs to do. This solution allows you to carry additional information (for example, the file unit) in the reimplemented class. I don't like this method because it clumps together two functionalities that may be unrelated, but in GUI apps it may be ok. Solution 2: observer pattern the algorithm class has a register(Observer) method, keeps a list of the registered observers and takes care of calling notify() on each of them. Observer::notify() needs a way to get the information from the Subject, so it either has two parameters, one with the Subject and the other with the data the Subject may pass, or just the Subject and the Observer is now in charge of querying it to fetch the relevant information. Solution 3: callbacks I tend to see the callback method as a lightweight observer. Instead of passing an object, you pass a callback, which may be a plain function, but also an instance method in those languages that allow it (for example, in python you can because passing an instance method will remain bound to the instance). C++ however does not allow it, because if you pass a pointer to an instance method, this will not be defined. Please correct me on this regard, my C++ is quite old. The problem with callbacks is that generally you have to pass them together with the data you want the callback to be invoked with. Callbacks don't store state, so you have to pass both the callback and the state to the Subject in order to find it at callback execution, together with any additional data the Subject may provide about the event is reporting. Question My question is relative to the fact that I need to implement the opening problem in a language that is not object oriented, namely Fortran 95, and I am fighting with my usual reasoning which is based on python assumptions and style. I think that in Fortran the concept is similar to C, with the additional trouble that in C you can store a function pointer, while in Fortran 95 you can only pass it around. Do you have any comments, suggestions, tips, and quirks on this regard (in C, C++, Fortran and python, but also in any other language, so to have a comparison of language features that can be exploited on this regard) on how to design for an algorithm that must report progress to some external entity, using state from both the algorithm and the external entity ?

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• Is throwing an error in unpredictable subclass-specific circumstances a violation of LSP?

  - by Motti Strom

  Say, I wanted to create a Java List<String> (see spec) implementation that uses a complex subsystem, such as a database or file system, for its store so that it becomes a simple persistent collection rather than an basic in-memory one. (We're limiting it specifically to a List of Strings for the purposes of discussion, but it could extended to automatically de-/serialise any object, with some help. We can also provide persistent Sets, Maps and so on in this way too.) So here's a skeleton implementation: class DbBackedList implements List<String> { private DbBackedList() {} /** Returns a list, possibly non-empty */ public static getList() { return new DbBackedList(); } public String get(int index) { return Db.getTable().getRow(i).asString(); // may throw DbExceptions! } // add(String), add(int, String), etc. ... } My problem lies with the fact that the underlying DB API may encounter connection errors that are not specified in the List interface that it should throw. My problem is whether this violates Liskov's Substitution Principle (LSP). Bob Martin actually gives an example of a PersistentSet in his paper on LSP that violates LSP. The difference is that his newly-specified Exception there is determined by the inserted value and so is strengthening the precondition. In my case the connection/read error is unpredictable and due to external factors and so is not technically a new precondition, merely an error of circumstance, perhaps like OutOfMemoryError which can occur even when unspecified. In normal circumstances, the new Error/Exception might never be thrown. (The caller could catch if it is aware of the possibility, just as a memory-restricted Java program might specifically catch OOME.) Is this therefore a valid argument for throwing an extra error and can I still claim to be a valid java.util.List (or pick your SDK/language/collection in general) and not in violation of LSP? If this does indeed violate LSP and thus not practically usable, I have provided two less-palatable alternative solutions as answers that you can comment on, see below. Footnote: Use Cases In the simplest case, the goal is to provide a familiar interface for cases when (say) a database is just being used as a persistent list, and allow regular List operations such as search, subList and iteration. Another, more adventurous, use-case is as a slot-in replacement for libraries that work with basic Lists, e.g if we have a third-party task queue that usually works with a plain List: new TaskWorkQueue(new ArrayList<String>()).start() which is susceptible to losing all it's queue in event of a crash, if we just replace this with: new TaskWorkQueue(new DbBackedList()).start() we get a instant persistence and the ability to share the tasks amongst more than one machine. In either case, we could either handle connection/read exceptions that are thrown, perhaps retrying the connection/read first, or allow them to throw and crash the program (e.g. if we can't change the TaskWorkQueue code).

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• How to build a 4x game?

  - by Marco

  I'm trying to study how succefully implement a 4x game. Area of interest: 1) map data: how to store stellars systems (graphs?), how to generate them and so on.. 2) multiplayer: how to organize code in a non graphical server and a client to display it 3) command system: what are patters to catch user and ai decisions and handle them, adding at first "explore" and "colonize" then "combat", "research", "spy" and so on (commands can affect ships, planets, research, etc..) 4) ai system: ai can use commands to expand, upgrade planets and ship I know is a big questions, so help is appreciated :D 1) Map data Best choice is have a graph to model a galaxy. A node is a stellar system and every system have a list of planets. Ship cannot travel outside of predefined paths, like in Ascendancy: http://www.abandonia.com/files/games/221/Ascendancy_2.png Every connection between two stellar systems have a cost, in turns. Generate a galaxy is only a matter of: - dimension: number of stellar systems, - variety: randomize number of planets and types (desertic, earth, etc..), - positions of each stellar system on game space - connections: assure that exist a path between every node, so graph is "connected" (not sure if this a matematically correct term) 2) Multiplayer Game is organized in turns: player 1, player 2, ai1, ai2. Server take care of all data and clients just diplay it and collect data change. Because is a turn game, latency is not a problem :D 3) Command system I would like to design a hierarchy of commands to take care of this aspect: abstract Genericcommand (target) ExploreCommand (Ship) extends genericcommand colonizeCommand (Ship) buildcommand(planet, object) and so on. In my head all this commands are stored in a queue for every planets, ships or reasearch center or spy, and each turn a command is sent to a server to apply command and change data state 4) ai system I don't have any idea about this. Is a big topic and what I want is a simple ai. Something like "expand and fight against everyone". I think about a behaviour tree to control ai moves, so I can develop an ai that try to build ships to expand and then colonize planets, upgrade them throught science and combat enemies. Could be done with a finite state machine too ? any ideas, resources, article are welcome!

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• Music Notation Editor - Refactoring view creation logic elseware

  - by Cyril Silverman

  Let me preface by saying that knowing some elementary music theory and music notation may be helpful in grasping the problem at hand. I'm currently building a Music Notation and Tablature Editor (in Javascript). But I've come to a point where the core parts of the program are more or less there. All functionality I plan to add at this point will really build off the foundation that I've created. As a result, I want to refactor to really solidify my code. I'm using an API called VexFlow to render notation. Basically I pass the parts of the editor's state to VexFlow to build the graphical representation of the score. Here is a rough and stripped down UML diagram showing you the outline of my program: In essence, a Part has many Measures which has many Notes which has many NoteItems (yes, this is semantically weird, as a chord is represented as a Note with multiple NoteItems, individual pitches or fret positions). All of the relationships are bi-directional. There are a few problems with my design because my Measure class contains the majority of the entire application view logic. The class holds the data about all VexFlow objects (the graphical representation of the score). It contains the graphical Staff object and the graphical notes. (Shouldn't these be placed somewhere else in the program?) While VexFlowFactory deals with actual creation (and some processing) of most of the VexFlow objects, Measure still "directs" the creation of all the objects and what order they are supposed to be created in for both the VexFlowStaff and VexFlowNotes. I'm not looking for a specific answer as you'd need a much deeper understanding of my code. Just a general direction to go in. Here's a thought I had, create an MeasureView/NoteView/PartView classes that contains the basic VexFlow objects for each class in addition to any extraneous logic for it's creation? but where would these views be contained? Do I create a ScoreView that is a parallel graphical representation of everything? So that ScoreView.render() would cascade down PartView and call render for each PartView and casade down into each MeasureView, etc. Again, I just have no idea what direction to go in. The more I think about it, the more ways to go seem to pop into my head. I tried to be as concise and simplistic as possible while still getting my problem across. Please feel free to ask me any questions if anything is unclear. It's quite a struggle trying to dumb down a complicated problem to its core parts.

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• Partition table corrupted (USB flash drive)

  - by 13ren

  It's an 8 GB Patriot thumb drive, which I've used extensively with lots of data. Today, it is detected, but all data is gone: (EDIT at least some data is still there, but the partition table is gone) EDIT @Sathya (thanks) here's the relevant output from sudo fdisk -l: Disk /dev/sdc: 8019 MB, 8019509248 bytes 247 heads, 62 sectors/track, 1022 cylinders Units = cylinders of 15314 * 512 = 7840768 bytes Disk /dev/sdc doesn't contain a valid partition table It looks like it is /dev/sdc, with that 8 GB... and no partition table. I tried to mount /dev/sdc (and then dmesg | tail): /media> sudo mount /dev/sdc mytmp mount: wrong fs type, bad option, bad superblock on /dev/sdc, missing codepage or other error In some cases useful info is found in syslog - try dmesg | tail or so /media> dmesg | tail [ 24.300000] sdc: unknown partition table [ 24.320000] sd 2:0:0:0: Attached scsi removable disk sdc [ 24.370000] usb-storage: device scan complete [ 26.870000] EXT2-fs error (device sdc): ext2_check_descriptors: Block bitmap for group 1 not in group (block 0)! [ 26.870000] EXT2-fs: group descriptors corrupted! [ 50.420000] unhashed dentry being revalidated: .DCOPserver_eeepc-brendanma__0 [ 50.430000] unhashed dentry being revalidated: .DCOPserver_eeepc-brendanma__0 [ 50.430000] unhashed dentry being revalidated: .DCOPserver_eeepc-brendanma__0 [ 5565.470000] EXT2-fs error (device sdc): ext2_check_descriptors: Block bitmap for group 1 not in group (block 0)! [ 5565.470000] EXT2-fs: group descriptors corrupted! EDIT @Col: results from testdisk Disk /dev/sdc - 8013 MB / 7642 MiB - CHS 1022 247 62 Current partition structure: Partition Start End Size in sectors Partition sector doesn't have the endmark 0xAA55 After I hit [proceed], it says: Structure: Ok. Keys A: add partition, L: load backup, Enter: to continue The "Structure: Ok." seems reassuring... will "A: add partition" make my old data accessible (if it's still there), or will it make a new, fresh partition? Another option is "[ MBR Code ] Write TestDisk MBR code to first sector" - would it be better to do this? EDIT I found that at least some of my data is still on the flash drive, by using the below, and searching for English text in less (like " the "): cat /dev/sde | tr -cd '\11\12\40\1540-\176' | less (The drive changed from "/dev/sdb" to "/dev/sde" because I connected some extra drives today). I've learnt that "/dev/sde1" would be the first partition; and "/dev/sde" is the whole drive. Because unix treats these devices just like files, you can use all the ordinary unix file commands on them, like cat, and then process them like any other stream of data. The tr above removes non-printable characters ("\40" is space, which I wanted to preserve). In less, you can use "/" to search, similar to Vim. How can I get my data back (assuming it's still there)? If only the partition table is corrupted, is there a standard "partition recovery tool"? Is there a way to "repartition" without deleting everything?

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• Is it evil to model JSON responses to classes when they are mostly smilar?

  - by Aybe

  Here's the problem : While implementing a C# wrapper for an online API (Discogs) I've been faced to a dilemma : quite often the responses returned have mostly similar members and while modeling these responses to classes, some questions surfaces on which way to go would be the best. Example : Querying for a 'release' or a 'master' will return an object that contains an array of 'artist', however these 'artists' do not exactly have the same members. Currently I decided to represent these 'artists' as a single 'Artist' class, against having respective 'ReleaseArtist' and 'MasterArtist' classes which soon becomes very confusing even though another problem arises : when a category (master or release) does not return these members, they will be null. Though it might sound confusing as well I find it less confusing than the former situation as I've tackled the problem by simply not showing null members when visualizing these objects. Is this the right approach to follow ? An example of these differences : public class Artist { public List<Alias> Aliases { get; set; } public string DataQuality { get; set; } public List<Image> Images { get; set; } public string Name { get; set; } public List<string> NameVariations { get; set; } public string Profile { get; set; } public string Realname { get; set; } public string ReleasesUrl { get; set; } public string ResourceUrl { get; set; } public string Uri { get; set; } public List<string> Urls { get; set; } } public class ReleaseArtist { public string Join { get; set; } public string Name { get; set; } public string Anv { get; set; } public string Tracks { get; set; } public string Role { get; set; } public string ResourceUrl { get; set; } public int Id { get; set; } }

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• What is meant by, "A user shouldn't decide whether it is an Admin or not. The Privileges or Security system should."

  - by GlenPeterson

  The example used in the question pass bare minimum data to a function touches on the best way to determine whether the user is an administrator or not. One common answer was: user.isAdmin() This prompted a comment which was repeated several times and up-voted many times: A user shouldn't decide whether it is an Admin or not. The Privileges or Security system should. Something being tightly coupled to a class doesn't mean it is a good idea to make it part of that class. I replied, The user isn't deciding anything. The User object/table stores data about each user. Actual users don't get to change everything about themselves. But this was not productive. Clearly there is an underlying difference of perspective which is making communication difficult. Can someone explain to me why user.isAdmin() is bad, and paint a brief sketch of what it looks like done "right"? Really, I fail to see the advantage of separating security from the system that it protects. Any security text will say that security needs to be designed into a system from the beginning and considered at every stage of development, deployment, maintenance, and even end-of-life. It is not something that can be bolted on the side. But 17 up-votes so far on this comment says that I'm missing something important.

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• Recommendations for a web-based help system

  - by ggkmath

  Hi Experts, I'm putting together a fairly large GUI. I'm a tech person, but more on the hardware side, not software. I'm wondering what software package would be best suited to enable me to generate a web-based help-system. Preferably it takes care of a lot of coding, allowing me to focus on the content. For example, the user would click on a link in the GUI when they have a question, that brings them to a web-based Help Guide, for example, providing an overview of how to use the GUI, perhaps a searchable index (key-word based index), table of contents, etc, for navigating through the Help Guide. My first thought was to program everything in XHTML using Dreamweaver, but my layout requirements are fairly modest (just figures and text, maybe a few equations), and I'd prefer not to spend a lot of time concentrating on the programming. Was wondering if any software existed that made generating web-based navigatable pages easy to create/publish. Again, I'm not really a programmer, so if there's something obvious out there, I'm probably not aware of it. Any advice much appreciated! Thanks in advance.

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• Do ORMs enable the creation of rich domain models?

  - by Augusto

  After using Hibernate on most of my projects for about 8 years, I've landed on a company that discourages its use and wants applications to only interact with the DB through stored procedures. After doing this for a couple of weeks, I haven't been able to create a rich domain model of the application I'm starting to build, and the application just looks like a (horrible) transactional script. Some of the issues I've found are: Cannot navigate object graph as the stored procedures just load the minimum amount of data, which means that sometimes we have similar objects with different fields. One example is: we have a stored procedure to retrieve all the data from a customer, and another to retrieve account information plus a few fields from the customer. Lots of the logic ends up in helper classes, so the code becomes more structured (with entities used as old C structs). More boring scaffolding code, as there's no framework that extracts result sets from a stored procedure and puts it in an entity. My questions are: has anyone been in a similar situation and didn't agree with the store procedure approch? what did you do? Is there an actual benefit of using stored procedures? appart from the silly point of "no one can issue a drop table". Is there a way to create a rich domain using stored procedures? I know that there's the posibility of using AOP to inject DAOs/Repositories into entities to be able to navigate the object graph. I don't like this option as it's very close to voodoo.

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• JS closures - Passing a function to a child, how should the shared object be accessed

  - by slicedtoad

  I have a design and am wondering what the appropriate way to access variables is. I'll demonstrate with this example since I can't seem to describe it better than the title. Term is an object representing a bunch of time data (a repeating duration of time defined by a bunch of attributes) Term has some print functionality but does not implement the print functions itself, rather they are passed in as anonymous functions by the parent. This would be similar to how shaders can be passed to a renderer rather than defined by the renderer. A container (let's call it Box) has a Schedule object that can understand and use Term objects. Box creates Term objects and passes them to Schedule as required. Box also defines the print functions stored in Term. A print function usually takes an argument and uses it to return a string based on that argument and Term's internal data. Sometime the print function could also use data stored in Schedule, though. I'm calling this data shared. So, the question is, what is the best way to access this shared data. I have a lot of options since JS has closures and I'm not familiar enough to know if I should be using them or avoiding them in this case. Options: Create a local "reference" (term used lightly) to the shared data (data is not a primitive) when defining the print function by accessing the shared data through Schedule from Box. Example: var schedule = function(){ var sched = Schedule(); var t1 = Term( function(x){ // Term.print() return (x + sched.data).format(); }); }; Bind it to Term explicitly. (Pass it in Term's constructor or something). Or bind it in Sched after Box passes it. And then access it as an attribute of Term. Pass it in at the same time x is passed to the print function, (from sched). This is the most familiar way for my but it doesn't feel right given JS's closure ability. Do something weird like bind some context and arguments to print. I'm hoping the correct answer isn't purely subjective. If it is, then I guess the answer is just "do whatever works". But I feel like there are some significant differences between the approaches that could have a large impact when stretched beyond my small example.

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• How to implment the database for event conditions and item bonuses for a browser based game

  - by Saifis

  I am currently creating a browser based game, and was wondering what was the standard approach in making diverse conditions and status bonuses database wise. Currently considering two cases. Event Conditions Needs min 1000 gold Needs min Lv 10 Needs certain item. Needs fulfillment of another event Status Bonus Reduces damage by 20% +100 attack points Deflects certain type of attack I wish to be able to continually change these parameters during the process of production and operation, so having them hard-coded isn't the best way. All I could come up with are the following two methods. Method 1 Create a table that contains each conditions with needed attributes Have a model named conditions with all the attributes it would need to set them conditions condition_type (level, money_min, money_max item, event_aquired) condition_amount prerequisite_condition_id prerequisite_item_id Method 2 write it in a DSL form that could be interpreted later in the code Perhaps something like yaml, have a text area in the setting form and have the code interpret it. condition_foo: condition_type :level min_level: 10 condition_type :item item_id: 2 At current Method 2 looks to be more practical and flexible for future changes, trade off being that all the flex must be done on the code side. Not to sure how this is supposed to be done, is it supposed to be hard coded? separate config file? Any help would be appreciated. Added For additional info, it will be implemented with Ruby on Rails

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• .Net Application & Database Modularity/Reuse

  - by Martaver

  I'm looking for some guidance on how to architect an app with regards to modularity, separation of concerns and re-usability. I'm working on an application (ASP.Net, C#) that has distinctly generic chunks of functionality, that I'd love to be able to lift out, all layers, into re-usable components. This means the module handles the database schema, data access, API, everything so that the next time I want to use it I can just register the module and hook into it. Developing modules of re-usable functionality is a no-brainer, but what is really confusing me is what to do when it comes to handling a core re-usable database schema that serves the module's functionality. In an ideal world, I would register a module and it would ensure that the associated database schema exists in the DB. I would code on the assumption that the tables exist, calling the module's functionality through the DLL, agnostic of the database layer. Kind of like Enterprise Library's Caching/Logging Application Block, which can create a DB schema in the target DB to use as a data store. My Questions is: What do you think is the best way to achieve this, firstly, in terms design architecture, and secondly solution structure. What patterns/frameworks do you know that exist & support this kind of thing? My thoughts so far: I mostly use Entity Framework and SQL Server DB Projects. I thought about a 'black box' approach to modules of functionality. I could use use a code-first approach in EF4, and use the ObjectContext to create a database when the module is initialized. However this means that all of the entities that my module encapsulates would be disconnected from the rest of the application because they belonged to an abstracted ObjectContext. Further - Creating appropriate indexes and references between domain entities and the module's entities would be impossible to do practically. I've thought of adopting Enterprise Library and creating my own Application Blocks. I'm not sure how this would play nice with Entity Framework (if at all) though. I like the idea of building on proven patterns & practices to encapsulate established, reusable functionality. I thought of abandoning Entity Framework for the Module, and just creating a separate DB schema for the module with its own set of stored procedures & ADO.Net. Then deploying the script at run-time if interrogation shows that it doesn't exist. But once again, for application developing outside of the application, I would want to use Entity Framework and I would have to use the module separately, disconnected from the domain ObjectContext. Has anyone had experience developing these sorts of full-stack modules? What advice can you offer? Am I biting off more than I can chew?

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• Why do Core Data sqlite table columns start with 'Z'?

  - by Dia

  I was looking at the sqlite table that Core Data generates and noticed that all table columns start with 'Z'. I realize this is an implementation detail, but I was curious as to why that's the case and if there was a design decision involved in this. Anyone happen to know or guess why? Here's a sample schema output of Core Data sqlite database: sqlite .schema CREATE TABLE ZPOST ( Z_PK INTEGER PRIMARY KEY, Z_ENT INTEGER, Z_OPT INTEGER, ZPOSTID INTEGER, ZUSER INTEGER, ZCREATEDAT TIMESTAMP, ZTEXT VARCHAR ); CREATE TABLE ZUSER ( Z_PK INTEGER PRIMARY KEY, Z_ENT INTEGER, Z_OPT INTEGER, ZUSERID INTEGER, ZAVATARIMAGEURLSTRING VARCHAR, ZUSERNAME VARCHAR ); CREATE TABLE Z_METADATA (Z_VERSION INTEGER PRIMARY KEY, Z_UUID VARCHAR(255), Z_PLIST BLOB); CREATE TABLE Z_PRIMARYKEY (Z_ENT INTEGER PRIMARY KEY, Z_NAME VARCHAR, Z_SUPER INTEGER, Z_MAX INTEGER);

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• What are the differences between abstract classes, interfaces, and when to use them

  - by user66662

  Recently I have started to wrap my head around OOP, and I am now to the point where the more I read about the differences between Abstract classes and Interfaces the more confused I become. So far, neither can be instantiated. Interfaces are more or less structural blueprints that determine the skeleton and abstracts are different by being able to partially develop code. I would like to learn more about these through my specific situation. Here is a link to my first question if you would like a little more background information: What is a good design model for my new class? Here are two classes I created: class Ad { $title; $description $price; function get_data($website){ } function validate_price(){ } } class calendar_event { $title; $description $start_date; function get_data($website){ //guts } function validate_dates(){ //guts } } So, as you can see these classes are almost identical. Not shown here, but there are other functions, like get_zip(), save_to_database() that are common across my classes. I have also added other classes Cars and Pets which have all the common methods and of course properties specific to those objects (mileage, weight, for example). Now I have violated the DRY principle and I am managing and changing the same code across multiple files. I intend on having more classes like boats, horses, or whatever. So is this where I would use an interface or abstract class? From what I understand about abstract classes I would use a super class as a template with all of the common elements built into the abstract class, and then add only the items specifically needed in future classes. For example: abstract class content { $title; $description function get_data($website){ } function common_function2() { } function common_function3() { } } class calendar_event extends content { $start_date; function validate_dates(){ } } Or would I use an interface and, because these are so similar, create a structure that each of the subclasses are forced to use for integrity reasons, and leave it up to the end developer who fleshes out that class to be responsible for each of the details of even the common functions. my thinking there is that some 'common' functions may need to be tweaked in the future for the needs of their specific class. Despite all that above, if you believe I am misunderstanding the what and why of abstracts and interfaces altogether, by all means let a valid answer to be stop thinking in this direction and suggest the proper way to move forward! Thanks!

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