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• Software development company business plan

  - by Navi

  I apologize in advance if this is the wrong forum for this question, so please forward me to the right place. I have about 10 years professional experience as software developer. Mostly on the Java platform doing server side programs. I have picked up a bit of Linux skills on the way as well. I know HTML and Javascript, so I can make a website that would not be too ugly, but I am not going to win any prizes with it. In fact I think I am pretty terrible in the user interface department. My initial plan is to do Android development. I read a few Android books and tried making a few apps. Since it is Java based I think I got the technical side down. Lately I have been thinking about iphone and Mac development, because of the relevant app store/development programs. The trouble is I don't know Objective C. As a side question, how long would it take me to become proficient in Objective C? Considering that I am working on my own and could hire somebody to help me for a short time for low wages if necessary what are my options? What are the pro and cons of the development programs app stores of Android and Apple? Which development/app stores are out there beside the ones I mentioned? Do you think it is necessary to find funds to get me started or should I just use my savings? If you have positive/negative experiences in a similar situations can you please share them? Thanks for your help.

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• What is the recommended MongoDB schema for this quiz-engine scenario?

  - by hughesdan

  I'm working on a quiz engine for learning a foreign language. The engine shows users four images simultaneously and then plays an audio file. The user has to match the audio to the correct image. Below is my MongoDB document structure. Each document consists of an image file reference and an array of references to audio files that match that image. To generate a quiz instance I select four documents at random, show the images and then play one audio file from the four documents at random. The next step in my application development is to decide on the best document schema for storing user guesses. There are several requirements to consider: I need to be able to report statistics at a user level. For example, total correct answers, total guesses, mean accuracy, etc) I need to be able to query images based on the user's learning progress. For example, select 4 documents where guess count is 10 and accuracy is <=0.50. The schema needs to be optimized for fast quiz generation. The schema must not cause future scaling issues vis a vis document size. Assume 1mm users who make an average of 1000 guesses. Given all of this as background information, what would be the recommended schema? For example, would you store each guess in the Image document or perhaps in a User document (not shown) or a new document collection created for logging guesses? Would you recommend logging the raw guess data or would you pre-compute statistics by incrementing counters within the relevant document? Schema for Image Collection: _id "505bcc7a45c978be24000005" date 2012-09-21 02:10:02 UTC imageFileName "BD3E134A-C7B3-4405-9004-ED573DF477FE-29879-0000395CF1091601" random 0.26997075392864645 user "2A8761E4-C13A-470E-A759-91432D61B6AF-25982-0000352D853511AF" audioFiles [ 0 { audioFileName "C3669719-9F0A-4EB5-A791-2C00486665ED-30305-000039A3FDA7DCD2" user "2A8761E4-C13A-470E-A759-91432D61B6AF-25982-0000352D853511AF" audioLanguage "English" date 2012-09-22 01:15:04 UTC } 1 { audioFileName "C3669719-9F0A-4EB5-A791-2C00486665ED-30305-000039A3FDA7DCD2" user "2A8761E4-C13A-470E-A759-91432D61B6AF-25982-0000352D853511AF" audioLanguage "Spanish" date 2012-09-22 01:17:04 UTC } ]

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• Oracle Customer Experience (CX) Solutions Make Retailers Merry

  - by Tuula Fai

  Tis the season to be jolly. If you’re a retailer, your level of jolliness depends on sales. So you watch trends like U.S. store traffic increasing 3.5% to 308 million on Black Friday but sales actually falling 1.8% to $11.2 billion. Fortunately, by the end of November, retail sales were up 3.7% over the previous year, thanks to life recovering after Hurricane Sandy. And online sales topped $1 billion for the first time ever! Who are the companies improving their sales online? They are big names like Walgreen’s Drugstore.com, Nordstrom’s HauteLook, and Intuit. More importantly, how are they doing it? They use cutting-edge business practices enabled by Oracle’s CX Cloud Service & Support solutions to: Increase conversions rates and order sizes (Customer Acquisition) Enhance customer satisfaction and loyalty (Customer Retention) Reduce contact center costs and improve agent productivity (Operational Efficiency). Acquisition + Retention + Operational Efficiency = Sustainable Growth and Profits. That’s the magic formula for retail customer service success. Don’t take our word for it. Look at the results of these Oracle customers: Walgreen’s Drugstore—30% sales conversion rate on chat sessions with 20% increase in shopping cart size Nordstrom’s HauteLook—40,000+ interactions per month—20% growth over last year— efficiently managed by 40 agents, with no increase in IT costs Intuit—50% increase in customer satisfaction and 70% decrease in cost per interaction Using Oracle’s CX Cloud & Service solutions, these retailers deliver consistent, relevant, and personalized experiences across all touchpoints, including social, mobile, and web. Their ability to connect with customers anytime, anywhere—providing the right answer at the right time—helps them create a defensible advantage in the marketplace. Want to learn more? Please visit http://www.oracle.com/goto/cloudlaunchpad for free resources on delivering exceptional customer service in the Cloud. Also, watch our YouTube channel to learn more about seamless multichannel retail and Winston Furnishings’ exceptional customer experience.

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• Octrees and Vertex Buffer Objects

  - by sharethis

  As many others I want to code a game with a voxel based terrain. The data is represented by voxels which are rendered using triangles. I head of two different approaches and want to combine them. First, I could once divide the space in chunks of a fixed size like many games do. What I could do now is to generate a polygon shape for each chunk and store that in a vertex buffer object (vbo). Each time a voxel changes, the polygon and vbo of its chunk is recreated. Additionally it is easy to dynamically load and reload parts of the terrain. Another approach would be to use octrees and divide the space in eight cubes which are divided again and again. So I could efficiently render the terrain because I don't have to go deeper in a solid cube and can draw that as a single one (with a repeated texture). What I like to use for my game is an octree datastructure. But I can't imagine how to use vbos with that. How is that done, or is this impossible?

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• What Pattern will solve this - fetching dependent record from database

  - by tunmise fasipe

  I have these classes class Match { int MatchID, int TeamID, //used to reference Team ... other fields } Note: Match actually have 2 teams which means 2 TeamID class Team { int TeamID, string TeamName } In my view I need to display List<Match> showing the TeamName. So I added another field class Match { int MatchID, int TeamID, //used to reference Team ... other fields string TeamName; } I can now do Match m = getMatch(id); m.TeamName = getTeamName(m.TeamId); //get name from database But for a List<Match>, getTeamName(TeamId) will go to the database to fetch TeamName for each TeamID. For a page of 10 Matches per page, that could be (10x2Teams)=20 trip to database. To avoid this, I had the idea of loading everything once, store it in memory and only lookup the TeamName in memory. This made me have a rethink that what if the records are 5000 or more. What pattern is used to solve this and how?

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• Static pages for large photo album

  - by Phil P

  I'm looking for advice on software for managing a largish photo album for a website. 2000+ pictures, one-time drop (probably). I normally use MarginalHack's album, which does what I want: pre-generate thumbnails and HTML for the pictures, so I can serve without needing a dynamic run-time, so there's less attack surface to worry about. However, it doesn't handle pagination or the like, so it's unwieldy for this case. This is a one-time drop for pictures from a wedding, with a shared usercode/password for distribution to the guests; I don't wish to put the pictures in a third-party hosting environment. I don't wish to use PHP, simply because that's another run-time to worry about, I might relent and use something dynamic if it's Python or Perl based (as I can maintain things written in those). I currently have: Apache serving static files, Album-generated, some sub-directories to divide up the content to be a little more manageable. Something like Album but with pagination already handled would be great, but I'm willing to have something a little more dynamic, if it lets people comment or caption and store the extra data in something like an sqlite DB. I'd want something light-weight, not a full-blown CMS with security updates every three months. I don't want to upload pictures of other peoples' children into a third-party free service where I don't know what the revenue model is. (For my site: revenue is none, costs out of pocket). Existing server hosting is *nix, Apache, some WSGI. Client-side I have MacOS. Any advice?

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• Why does my mic boost automatically go to 100 on every boot?

  - by Ben

  When my computer turns on, it automatically sets the "mic boost" sound setting to 100. This causes a loud static sound in my speakers. I can manually go to alsamixer and turn the mic boost down manually, but I would prefer it if I didn't have to do this every time I turn the computer on. I've tried running sudo alsactl store after fixing the settings, and this does save them, but I have to run sudo alsactl restore to restore the settings. This means that I have to manually fix the sound every time I start the computer anyway, so it isn't really a fix. I tried putting sudo alsactl restore in my startup programs, but that didn't seem to fix anything. I'm running Ubuntu 12.04, but I started having this problem before upgrading from 11.10. I'm using a Sony Vaio laptop. I'm not really sure what made it start; it seemed like I just started having the problem randomly one day. Any help would be appreciated! Edit: here is the output from running amixer: http://paste.ubuntu.com/1060080/

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• Microsoft Changes Developer Account Registration Requirements

  - by Tim Murphy

  Over the last couple of weeks I have noticed that Microsoft seems to have changed the requirements for Corporate accounts.  These requirements were not in effect when I originally setup the account for the company that I work for.  We also recently had our corporate account canceled without explanation and are in the process of working to get it reinstated.  This all seems to revolve around rules to increase confidence that in the producers of content.  They are now having Symantec validate a company based on legal documents. In the past there have been problems with getting credit cards accepted.  We have had to setup new Live IDs to satisfy whatever glitch the system had or unexplainable requirement.  I am hoping that in the time that has elapsed these problems have been resolved. In truth I can’t say that these new requirements weren’t always in place, but it is getting frustrating to help clients setup accounts.  I am encourage that they have taken steps to safeguard the consumer from Joe-fly-by-night, but they also need to make sure that the process doesn’t become so complex that it drives away companies from participating in the store.  We will have to keep an eye on this as things evolve. del.icio.us Tags: Windows Phone Development,Windows 8 Development,Windows Phone,Windows 8,Registration,Corporate Accounts

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• How to handle multiple pages of the same site with the same outlinks

  - by pandafromchina

  I am developing a back link tool for Chinese SEO (our web site URL is: http://link.aizhan.com just like ahrefs.com. I encountered a problem which is how to handle multiple pages of the same site with the same out links. For example: Most pages of bbs.chinaz.com have the same out links such as: bbs.chinaz.com/Tea/thread-6293993-1-1.html bbs.chinaz.com/Tea/list-1.html bbs.chinaz.com/alimama/thread-6265032-1-1.html bbs.chinaz.com/alimama/thread-6265032-2-1.html?userid=-1&extParms= bbs.chinaz.com/Shuiba/list-1.html bbs.chinaz.com/FeedBack/thread-4456753-1-1.html etc.. All of the pages have the same out links in the top of the page: www.cnzz.com(anchor text:????) www.313.com(????) www.idc123.com(????) Suppose I store these outlinks into database. The SEO will find there are six backlinks from bbs.chinaz.com of www.cnzz.com. This is obviously no sense for the SEO. Can you tell me how do you deal with this problem?

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• What's the best way to manage reusable classes/libraries separately?

  - by Tom

  When coding, I naturally often come up with classes or a set of classes with a high reusability. I'm looking for an easy, straight-forward way to work on them separately. I'd like to be able to easily integrate them into any project; it also should be possible to switch to a different version with as few commands as possible. Am I right with the assumption that git (or another VCS) is best suited for this? I thought of setting up local repositories for each class/project/library/plugin and then just cloning/pulling them. It would be great if I could reference those projects by name, not by the full path. Like git clone someproject. edit: To clarify, I know what VCS are about and I do use them. I'm just looking for a comfortable way to store and edit some reusable pieces of code (including unit tests) separately and to be able to include them (without the unit tests) in other projects, without having to manually copy files. Apache Maven is a good example, but I'm looking for a language-independent solution, optimally command-line-based.

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• Storing editable site content?

  - by hmp

  We have a Django-based website for which we wanted to make some of the content (text, and business logic such as pricing plans) easily editable in-house, and so we decided to store it outside the codebase. Usually the reason is one of the following: It's something that non-technical people want to edit. One example is copywriting for a website - the programmers prepare a template with text that defaults to "Lorem ipsum...", and the real content is inserted later to the database. It's something that we want to be able to change quickly, without the need to deploy new code (which we currently do twice a week). An example would be features currently available to the customers at different tiers of pricing. Instead of hardcoding these, we read them from database. The described solution is flexible but there are some reasons why I don't like it. Because the content has to be read from the database, there is a performance overhead. We mitigate that by using a caching scheme, but this also adds some complexity to the system. Developers who run the code locally see the system in a significantly different state compared to how it runs on production. Automated tests also exercise the system in a different state. Situations like testing new features on a staging server also get trickier - if the staging server doesn't have a recent copy of the database, it can be unexpectedly different from production. We could mitigate that by committing the new state to the repository occasionally (e.g. by adding data migrations), but it seems like a wrong approach. Is it? Any ideas how best to solve these problems? Is there a better approach for handling the content that I'm overlooking?

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• How did we get saddled with the (hierarchical) filesystem as the basic data structure?

  - by user1936

  I'm self-taught and I don't have a CS degree. The more I've been learning about data structure, the more I wonder, in this day and age, how are we still saddled with the filesystem, with directories and files, as the basic data storage structure on the OS? I understand the simplicity of it, but it seems nowadays that there could be more options available natively. As far as I'm aware, the only project to improve the basic functionality of the filesystem was ReiserFS, where you could tell what line of a file was changed by whom, and when. For instance, if I could have native tagging for files, where I could tag images, diagrams, word-processing documents, an entire code repository, all as belonging to a single project, that would really be helpful to me. Since I'm stuck in the filesystem paradigm, I know that I could put all those into a single folder/directory, but what if they already exist in disparate directories, and they need to stay there? I know there are programs out there that can do this, but why aren't they on the filesystem? Something that would be nice to have is some kind of relational feature in the filesystem, like you get with RDBMSes. I understand that that was supposed to be part of Vista/7, but that fell off the feature list too. Sure, any program can store a binary file and have any data structure it wants in it, by why couldn't the OS offer more complex ways of storing data, beyond the simple heirarchy of the filesystem?

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• Matrices: Arrays or separate member variables?

  - by bjz

  I'm teaching myself 3D maths and in the process building my own rudimentary engine (of sorts). I was wondering what would be the best way to structure my matrix class. There are a few options: Separate member variables: struct Mat4 { float m11, m12, m13, m14, m21, m22, m23, m24, m31, m32, m33, m34, m41, m42, m43, m44; // methods } A multi-dimensional array: struct Mat4 { float[4][4] m; // methods } An array of vectors struct Mat4 { Vec4[4] m; // methods } I'm guessing there would be positives and negatives to each. From 3D Math Primer for Graphics and Game Development, 2nd Edition p.155: Matrices use 1-based indices, so the first row and column are numbered 1. For example, a12 (read “a one two,” not “a twelve”) is the element in the first row, second column. Notice that this is different from programming languages such as C++ and Java, which use 0-based array indices. A matrix does not have a column 0 or row 0. This difference in indexing can cause some confusion if matrices are stored using an actual array data type. For this reason, it’s common for classes that store small, fixed size matrices of the type used for geometric purposes to give each element its own named member variable, such as float a11, instead of using the language’s native array support with something like float elem[3][3]. So that's one vote for method one. Is this really the accepted way to do things? It seems rather unwieldy if the only benefit would be sticking with the conventional math notation.

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• Implementing my Entity System. Questions about some problems I have found.

  - by Notbad

  Hi!, Well during this week I have deciding about implementation of my entity system. It is a big topic so it has been difficult to take one option from the whole. This has been my decision: 1) I don't have an entity class it is just an id. 2) I have systems that contain a list of components (the list is homegenous, I mean, RenderSystem will just have RenderComponents). 3) Compones will be just data. 4) There would be some kind of "entity prototypes" in a manager or something from we will create entity instances.Ideally they will define the type of components it has and initialization data. 5) Prototype code to create an entity (this is from the top of my head): int id=World::getInstance()->createEntity("entity template"); 6) This will notify all systems that a new entity has been created, and if the entity needs a component that the system handles it will add it to the entity. Ok, this are the ideas. Let's see if some can help with the problems: 1) The main problem is this templates that are sent to the systems in creation process to populate the entity with needed components. What would you use, an OR(ed) int?, a list of strings?. 2) How to do initialization for components when the entity has been created? How to store this in the template? I have thought about having a function in the template that is virtual and after entity is created an populated, gets the components and sets initialization values. 3) Don't you think this is a lot of work for just an entity creation?. Sorry for the long post, I have tried to expose my ideas and finding in order other could have a start beside exposing my problems. Thanks in advance, Notbad.

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• MultiSelectChoice: How to get underlying values selected

  - by Vijay Mohan

  Let's say you include a multiselectchoice component in your jspx/jsff page, which has <f;selectItem> or <af:forEach> binded to a VO iterator to populate the multiselectchoice and the value property of which is binded to a List attribute binding.When the user selects some items in that choice List then u want the actual values to be posted.You can check the valuepassthrough flag to true , but many a times it doesn't help and you end up getting the indexes of multiselect values.Here is a way to get the actual values..Lets say in the bean u have a utility method to achieve this as follows..You can associate a valueChangeListener for the multiselectchoice as follows..public void onValueChangeOfLOV(ValueChangeEvent valueChangeEvent) { //get array of indexes of selected items in master list List valueIndexes = (List)valueChangeEvent.getNewValue(); String concatCodes = returnSelectmanyChoiceValues(valueIndexes,"YourIterator", "YourAttribute"); } public String returnSelectmanyChoiceValues(List valueIndexes,String iterName, String idAttrName){ DCBindingContainer dc = (DCBindingContainer)BindingContext.getCurrent().getCurrentBindingsEntry(); DCIteratorBinding iter = dc.findIteratorBinding(iterName); ViewObject vo = iter.getViewObject(); String codes = ""; for(Object index : valueIndexes){ String iIndex = (String)index; Row row = vo.getRowAtRangeIndex(Integer.parseInt(iIndex)); codes = codes +(String)row.getAttribute(idAttrName)+","; } //remove last "," if(codes.endsWith(",")) codes = codes.substring(0,codes.lastIndexOf(",")); return codes; }This will return u a comma separated values of the selected items. if you want thenYou can store it in a List.

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• Retrieving database column using JSON [migrated]

  - by arokia

  I have a database consist of 4 columns (id-symbol-name-contractnumber). All 4 columns with their data are being displayed on the user interface using JSON. There is a function which is responisble to add new column to the database e.g (countrycode). The coulmn is added successfully to the database BUT not able to show the new added coulmn in the user interface. Below is my code that is displaying the columns. Can you help me? table.php $(document).ready(function () { // prepare the data var theme = getDemoTheme(); var source = { datatype: "json", datafields: [ { name: 'id' }, { name: 'symbol' }, { name: 'name' }, { name: 'contractnumber' } ], url: 'data.php', filter: function() { // update the grid and send a request to the server. $("#jqxgrid").jqxGrid('updatebounddata', 'filter'); }, cache: false }; var dataAdapter = new $.jqx.dataAdapter(source); // initialize jqxGrid $("#jqxgrid").jqxGrid( { source: dataAdapter, width: 670, theme: theme, showfilterrow: true, filterable: true, columns: [ { text: 'id', datafield: 'id', width: 200 }, { text: 'symbol', datafield: 'symbol', width: 200 }, { text: 'name', datafield: 'name', width: 100 }, { text: 'contractnumber', filtertype: 'list', datafield: 'contractnumber' } ] }); }); data.php <?php #Include the db.php file include('db.php'); $query = "SELECT * FROM pricelist"; $result = mysql_query($query) or die("SQL Error 1: " . mysql_error()); $orders = array(); // get data and store in a json array while ($row = mysql_fetch_array($result, MYSQL_ASSOC)) { $pricelist[] = array( 'id' => $row['id'], 'symbol' => $row['symbol'], 'name' => $row['name'], 'contractnumber' => $row['contractnumber'] ); } echo json_encode($pricelist); ?>

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• How do I simplify a 2D game grid for level management while keeping its by-pixel features?

  - by Eric Thoma

  (I cross-posted this from StackOverflow as this seems to be a more appropriate forum. I've looked around a little here and I did not find an answer, so I hope this is not a recurring question.) This is a question dealing with 2D world design. I am playing around by creating a 2D bird's eye view shooter game, and I am looking to make the game sleek and advanced. I hope to be able to write physics so projectiles have momentum and knock-down properties. I am immediately running into the problem of world design. I need a way to have level files that store everything there is about a game. This is easiest by just having a grid of objects. But there are thin-walls and other objects that don't seem to fit into a traditional cell of a grid. I want to be able to fit all these together so I can streamline level design; so I don't have to put in the exact pixel-specific start and end of a wall. There doesn't seem to be an obvious translation from level file to game without forcing myself into a pacman-life scenario, meaning a scenario where the game feels boxy and discrete. There is a contrast between the smoothly (relatively) moving characters and finite jumps in a grid. I would appreciate an answer that would describe implementation options or point me to resources that do. I would also appreciate references to sites that teach game design. The language I am using is Java (although I would love to use C or C++, but I can never find convenient resources in those languages). Thank you for any answers. Please leave any questions in the space below; I will be able to answer them later tonight (28th Nov).

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• Is it reasonable to require passwords when users sign into my application through social media accounts?

  - by BrMcMullin

  I've built an application that requires users to authenticate with one or more social media accounts from either Facebook, Twitter, or LinkedIn. Edit Once the user has signed in, an 'identity' for them is maintained in the system, to which all content they create is associated. A user can associate one account from each of the supported providers with this identity. I'm concerned about how to protect potential users from connecting the wrong account to their identity in our application. /Edit There are two main scenarios that could happen: User has multiple accounts on one of the three providers, and is not logged into the one s/he desires. User comes to a public or shared computer, in which the previous user left themselves logged into one of the three providers. While I haven't encountered many examples of this myself, I'm considering requiring users to password authenticate with Facebook, Twitter, and LinkedIn whenever they are signing into our application. Is that a reasonable approach, or are there reasons why many other sites and applications don't challenge users to provide a user name and password when authorizing applications to access their social media accounts? Thanks in advance! Edit A clarification, I'm not intending to store anyone's user name and password. Rather, when a user clicks the button to sign in, with Facebook as an example, I'm considering showing an "Is this you?" type window. The idea is that a user would respond to the challenge by either signing into Facebook on the account fetched from the oauth hash, or would sign into the correct account and the oauth callback would run with the new oauth hash data.

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• Is there an idiot's guide to software licensing somewhere?

  - by Karpie

  Basically, my knowledge on the issue is zilch other than the fact that open-source and closed-source exists. I'm a web developer (not a designer in the slightest), so I look online for things like icons. I've always been a big fan of these icons, which have a Creative Commons Attribution 2.5 License. As far as I can see, this license says 'do whatever you want with them as long as you have a link back to me somewhere'. Is that assumption correct? Just today I found a new icon set, with a much more confusing license (found here), and to be quite honest I have no idea if I'm allowed to use them or not. At the moment I want to just use them for toy stuff that might never see the light of day, but then my source code is stored on Github, is it legal to store the icons there where they're publicly accessible? If I put them on my personal website that might have ads on it to make me five cents every now and then, is that legal? If I use them on a site that offers a free service to users, is that legal? If that site then starts making money (via things like paid subscriptions) or gets bought out by someone (highly unlikely but one day possible) is that legal? Is there some noob guide out there that explains all this stuff, because I would hate to start using this sort of stuff now only to have to change it all later. Even if I buy the icons, there's still licensing issues that I don't understand! :( And this sort of stuff keeps popping up more and more often...

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• How do I dissuade users from using the same password with similar systems?

  - by Resorath

  I'm building a web application that connects to other web services (using strictly anonymous binding, so no user passwords are being used). However the web application maintains its own users itself, and is required to ask certain details such as e-mail addresses and public linking information to these other web services (for example, a username but not a password). I want to deter or prevent users from reusing passwords in my application that they have also used in the applications I'm linking to. For example, if I ask for their e-mail and provide me with their gmail address, I don't want them using their gmail password for my system. Another example would be reusing a password to a linked system in which they also gave me their username. One idea I had was to simply try using the information they gave me, along with the password they are trying to store and log in to these external web applications to test the password - then immediately unbind if I was successful and ask the user to use a different password. However I suspect there is a host of morale and legal issues there. The reason this is a big deal to me is accountability. My application is simply not funded enough to invest properly in security around user passwords. A salted, hashed password in a public SQL-like database is as secure as it gets. So if passwords and linked usernames or e-mails get out, I don't want my userbase compromised.

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• Are there design patterns or generalised approaches for particle simulations?

  - by romeovs

  I'm working on a project (for college) in C++. The goal is to write a program that can more or less simulate a beam of particles flying trough the LHC synchrotron. Not wanting to rush into things, me and my team are thinking about how to implement this and I was wondering if there are general design patterns that are used to solve this kind of problem. The general approach we came up with so far is the following: there is a World that holds all objects you can add objects to this world such as Particle, Dipole and Quadrupole time is cut up into discrete steps, and at each point in time, for each Particle the magnetic and electric forces that each object in the World generates are calculated and summed up (luckily electro-magnetism is linear). each Particle moves accordingly (using a simple estimation approach to solve the differential movement equations) save the Particle positions repeat This seems a good approach but, for instance, it is hard to take into account symmetries that might be present (such as the magnetic field of each Quadrupole) and is this thus suboptimal. To take into account such symmetries as that of the Quadrupole field, it would be much easier to (also) make space discrete and somehow store form of the Quadrupole field somewhere. (Since 2532 or so Quadrupoles are stored this should lead to a massive gain of performance, not having to recalculate each Quadrupole field) So, are there any design patterns? Is the World-approach feasible or is it old-fashioned, bad programming? What about symmetry, how is that generally taken into acount?

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• Is there a simple, flat, XML-based query-able data storage solution? [closed]

  - by alex gray

  I have been in long pursuit of an XML-based query-able data store, and despite continued searches and evaluations, I have yet to find a solution that meets the my needs, which include: Data is wholly contained within XML nodes, in flat text files. There is a "native" - or at least unobtrusive - method with which to perform Create/Read/Update/Delete (CRUD) operations onto the "schema". I would consider access via http, XHR, javascript, PHP, BASH, or PERL to be unobtrusive, dependent on the complexity of the set of dependencies. Server-side file-system reads and writes. A client-side interface element, accessible in any browser without a plug-in. Some extra, preferred (but optional) requirements include: Respond to simple SQL, or similarly syntax queries. Serve the data on a bare bones https server, with no "extra stuff", either via XMLHTTPRequest, HTTP proper, or JSON. A few thoughts: What I'm looking for may be possible via some Java server implementations, but for the sake of this question, please do not suggest that - unless it meets ALL the requirements. Java, especially on the client-side is not really an option, nor is it appealing from a development viewpoint.* I know walking the filesystem is a stretch, and I've heard it's possible with XPATH or XSLT, but as far as I know, that's not ready for primetime, nor even yet a recommendation. However the ability to recursively traverse the filesystem is needed for such a system to be of useful facility. At this point, I have basically implemented what I described via, of all things, CGI and Bash, but there has to be an easier way. Thoughts?

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• What is the standard technique for shifting the frames of a sprite according to user input?

  - by virtual__

  From my own experience, I developed two techniques for changing the sprites of a character that's reacting to user input -- this in the context of a classic 2D platformer. The first one is to store all character's pixmaps in a list, putting the index of the currently used pixmap in an ordinary variable. This way, every time the player presses a key -- say the right arrow for moving the character forward -- the graphics engine sees what's the next pixmap to draw, draws it, and increments the index counter. That's a pretty common approach I believe, the problem is that in this case the animation's quality depends not only on the number of sprites available but also on how often your engine listens to user input. The second technique is to actually play an animation every key press event. For this you can use any sort of animation framework you want. It's only necessary to set the timer, the animation steps and to call the animation's play() method on your key press event handler. The problem with that approach is that is lacks responsiveness, since the character won't react to any input while the current animation is still being played. What I want to know is whether you are using one of these techniques -- or something similar -- in your games, or whether there's a standard method for animating sprites out there that's widely known by everybody but me.

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• Tips on how to notify a user of new features in your game (Android)

  - by brent777

  I have noticed a problem when releasing new features for a game that I wrote for Android and published on Google Play Store. Because my game is "stage-based" - and not a game like Hay Day, for example, where users will just go into the game every day since it can't really be finished - my users are not aware of new features that I release for the game. For example, if I publish a new version of my game and it contains a couple new stages, most of their devices will just auto-update the game and they don't even notice this and think to check out what's new. So this is why an approach like popping open a dialog that showcases the new feature(s) when they open the game for the first time after the update was done is not really sufficient. I am looking for some tips on an approach that will draw my users back into the game and then they could read more detail about new features on such a dialog. I was thinking of something like a notification that tells them to check out the new features after an update is done but I am not sure if this is a good idea. Any suggestions to help me solve this problem would be awesome.

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• How can I malloc an array of struct to do the following using file operation?

  - by RHN

  How can malloc an array of struct to do the following using file operation? the file is .txt input in the file is like: 10 22 3.3 33 4.4 I want to read the first line from the file and then I want to malloc an array of input structures equal to the number of lines to be read in from the file. Then I want to read in the data from the file and into the array of structures malloc. Later on I want to store the size of the array into the input variable size. return an array.After this I want to create another function that print out the data in the input variable in the same form like input file and suppose a function call clean_data will free the malloc memory at the end. I have tried somthing like: struct input { int a; float b,c; } struct input* readData(char *filename,int *size); int main() { return 0; } struct input* readData(char *filename,int *size) { char filename[] = "input.txt"; FILE *fp = fopen(filename, "r"); int num; while(!feof(fp)) { fscanf(fp,"%f", &num); struct input *arr = (struct input*)malloc(sizeof(struct input)); } }

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