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  • Doing powerups in a component-based system

    - by deft_code
    I'm just starting really getting my head around component based design. I don't know what the "right" way to do this is. Here's the scenario. The player can equip a shield. The the shield is drawn as bubble around the player, it has a separate collision shape, and reduces the damage the player receives from area effects. How is such a shield architected in a component based game? Where I get confused is that the shield obviously has three components associated with it. Damage reduction / filtering A sprite A collider. To make it worse different shield variations could have even more behaviors, all of which could be components: boost player maximum health health regen projectile deflection etc Am I overthinking this? Should the shield just be a super component? I really think this is wrong answer. So if you think this is the way to go please explain. Should the shield be its own entity that tracks the location of the player? That might make it hard to implement the damage filtering. It also kinda blurs the lines between attached components and entities. Should the shield be a component that houses other components? I've never seen or heard of anything like this, but maybe it's common and I'm just not deep enough yet. Should the shield just be a set of components that get added to the player? Possibly with an extra component to manage the others, e.g. so they can all be removed as a group. (accidentally leave behind the damage reduction component, now that would be fun). Something else that's obvious to someone with more component experience?

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  • implementing match-making & community system for multiplayer games

    - by kamziro
    These days, games often have multiplayer portals with chat channels & match making system for the multiplayer aspects of the game. An example would be battle.net, magic the gathering online's chat rooms, halo etc. Now, for the rest of us indie gamers that probably won't be able to spend much development effort on creating those back-ends from scratch, what options do we have? I was thinking of something along the line of using IRC as the backbone of the system. From there, the "community" aspect and implement player tracking, game tracking and match making on top of that. It seems to be what the old battle.net (brood war era) used to be. The question is, is this easy to do? What does it take to run an irc server, and I suppose this also requires writing an IRC client (which seems to have been done a lot these days?)? If there are other ways as well (say, an open framework for this stuff), let's hear them too.

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  • Updating a database connection password using a script

    - by Tim Dexter
    An interesting customer requirement that I thought was worthy of sharing today. Thanks to James for the requirement and Bryan for the proposed solution and me for testing the solution and proving it works :0) A customers implementation of Sarbanes Oxley requires them to change all database account passwords every 90 days. This is scripted leveraging shell scripts today for most of their environments. But how can they manage the BI Publisher connections? Now, the customer is running 11g and therefore using weblogic on the middle tier, which is the first clue to Bryans proposed solution. To paraphrase and embellish Bryan's solution a little; why not use a JNDI connection from BIP to the database. Then employ the web logic scripting engine to make updates to the JNDI as needed? BIP is completely uninvolved and with a little 'timing' users will be completely unaware of the password updates i.e. change the password when reports are not being executed. Perfect! James immediately tracked down the WLST script that could be used here, http://middlewaremagic.com/weblogic/?p=4261 (thanks Ravish) Now it was just a case of testing the theory. Some steps: Create the JNDI connection in WLS Create the JNDI connection in BI Publisher pointing to the WLS connection Build new data models using or re-point data sources to use the JNDI connection. Create the WLST script to update the WLS JNDI password as needed. Test! Some details. Creating the JNDI connection in web logic is pretty straightforward. Log into hte console and look for Data Sources under the Services section of the home page and click it Click New >> Generic Datasource Give the connection a name. For the JNDI name, prefix it with 'jdbc/' so I have 'jdbc/localdb' - this name is important you'll need it on the BIP side. Select your db type - this will influence the drivers and information needed on the next page. Being a company man, Im using an Oracle db. Click Next Select the driver of choice, theres lots I know, you can read about them I just chose 'Oracle's Driver (Thin) for Instance connections; Versions 9.0.1 and later' Click Next >> Next Fill out the db name (SID), server, port, username to connect and password >> Next Test the config to ensure you can connect. >> Next Now you need to deploy the connection to your BI server, select it and click Next. You're done with the JNDI config. Creating the JNDI connection on the Publisher side is covered here. Just remember to the connection name you created in WLS e.g. 'jdbc/localdb' Not gonna tell you how to do this, go read the user guide :0) Suffice to say, it works. This requires a little reading around the subject to understand the scripting engine and how to execute scripts. Nicely covered here. However a bit of googlin' and I found an even easier way of running the script. ${ServerHome}/common/bin/wlst.sh updatepwd.py Where updatepwd.py is my script file, it can be in another directory. As part of the wlst.sh script your environment is set up for you so its very simple to execute. The nitty gritty: Need to take Ravish's script above and create a file with a .py extension. Its going to need some modification, as he explains on the web page, to make it work in your environment. I played around with it for a while but kept running into errors. The script as is, tries to loop through all of your connections and modify the user and passwords for each. Not quite what we are looking for. Remember our requirement is to just update the password for a given connection. I also found another issue with the script. WLS 10.x does not allow updates to passwords using clear type ie un-encrypted text while the server is in production mode. Its a bit much to set it back to developer mode bounce it, change the passwords and then bounce and then change back to production and bounce again. After lots of messing about I finally came up with the following: ############################################################################# # # Update password for JNDI connections # ############################################################################# print("*** Trying to Connect.... *****") connect('weblogic','welcome1','t3://localhost:7001') print("*** Connected *****") edit() startEdit() print ("*** Encrypt the password ***") en = encrypt('hr') print "Encrypted pwd: ", en print ("*** Changing pwd for LocalDB ***") dsName = 'LocalDB' print 'Changing Password for DataSource ', dsName cd('/JDBCSystemResources/'+dsName+'/JDBCResource/'+dsName+'/JDBCDriverParams/'+dsName) set('PasswordEncrypted',en) save() activate() Its pretty simple and you can expand on it to loop through the data sources and change each as needed. I have hardcoded the password into the file but you can pass it as a parameter as needed using the properties file method. Im not going to get into the detail of that here but its covered with an example here. Couple of points to note: 1. The change to the password requires a server bounce to get the changes picked up. You can add that to the shell script you will use to call the script above. 2. The script above needs to be run from the MW_HOME\user_projects\domains\bifoundation_domain directory to get the encryption libraries set correctly. My command to run the whole script was: d:\oracle\bi_mw\wlserver_10.3\common\bin\wlst.cmd updatepwd.py - where wlst.cmd is the scripting command line and updatepwd.py was my update password script above. I have not quite spoon fed everything you need to make it a robust script but at least you know you can do it and you can work out the rest I think :0)

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  • Reuse the data CRUD methods in data access layer, but they are updated too quickly

    - by ValidfroM
    I agree that we should put CRUD methods in a data access layer, However, in my current project I have some issues. It is a legacy system, and there are quite a lot CRUD methods in some concrete manager classes. People including me seem to just add new methods to it, rather than reuse the existing methods. Because We don't know whether the existing method is what we need Even if we have source code, do we really need read other's code then make decision? It is updated too quickly. Do not have time get familiar with the DAO API. Back to the question, how do you solve that in your project? If we say "reuse", it really needs to be reusable rather than just an excuse.

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  • Low coupling and tight cohesion

    - by hidayat
    Of course it depends on the situation. But when a lower lever object or system communicate with an higher level system, should callbacks or events be preferred to keeping a pointer to higher level object? For example, we have a world class that has a member variable vector<monster> monsters. When the monster class is going to communicate with the world class, should I prefer using a callback function then or should I have a pointer to the world class inside the monster class?

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  • Lending epub files for limited time to users

    - by JP Hellemons
    I am looking for components to build a digital library who lends people epub (ebooks) for about a week. It's like a digital version of the offline old public library. Now I have found several flash (pdf) file streaming solutions. But that would require an active internet link. And like the public library, you are able to take your books to the beach or pool on holiday abroad where you have no connection. So streaming is no option. The other file restriction method I have found was DRM, but that would require a really expensive license of Adobe Content Server 4 which is not suitable for my little hobby project. But it seems that adobe content server and Adobe Digital Editions is the only option at the moment. Or are there open source alternatives?

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  • Leveraging Code in Ever Bigger Games

    - by ashes999
    Summary: The same way that I continually build complex engines and libraries within a single platform and technology to allow me to build increasingly bigger and better games, how to continue this when development crosses into different platforms? If I switch platforms, how do I leverage past code and experiences? Games are hard to build. Big games are even harder to build. I've decided that to be able to make big games, I need to start building smaller games, and building up an asset base of code, assets (graphics, sounds), tools, and most importantly, game engines, so that I can eventually get there. One game at a time. Let me give an analogy. To build an MMO 3D RPG, I would approach this by building and releasing small games with increasingly more features. This could entail, for example: A simple 2D game A tile-based game A game with RPG elements (items, equipment, monsters, battle) A full-fledged RPG A 3D RPG The problem now is if I have to change platforms or tools, I don't know how to leverage past code-bases (and experience) to start with a mature product. Right now, I'm writing Silverlight (FlatRedBall) games. Let's say I stick with this for ten years, and then suddenly decide to write a PS6 game, which is in a different programming language entirely. Granted, I have ten years of game-development experience (and correspondingly ten years of professional software development experience from my day job) to back me up. But I would still like some way to transplant that 2D RPG engine into the new programming language, or else leverage it somehow. Is this even possible? What are my options?

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  • When using membership provider, do you use the user ID or the username?

    - by Chris
    I've come across this is in a couple of different applications that I've worked on. They all used the ASP.NET Membership Provider for user accounts and controlling access to certain areas, but when we've gotten down into the code I've noticed that in one we're passing around the string based user name, like "Ralph Waters", or we're passing around the Guid based user ID from the membership table. Now both seem to work. You can make methods which get by username, or get by user ID, but both have felt somewhat "funny". When you pass a string like "Ralph Waters" you're passing essentially two separate words that make up a unique identifier. And with a Guid, you're passing around a string/number combination which can be cast and made unique. So my question is this; when using Membership Provider, which do you use, the username or the user ID to get back to the user? Thanks all!

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  • Doing powerups in a component-based system

    - by deft_code
    I'm just starting really getting my head around component based design. I don't know what the "right" way to do this is. Here's the scenario. The player can equip a shield. The the shield is drawn as bubble around the player, it has a separate collision shape, and reduces the damage the player receives from area effects. How is such a shield architected in a component based game? Where I get confused is that the shield obviously has three components associated with it. Damage reduction / filtering A sprite A collider. To make it worse different shield variations could have even more behaviors, all of which could be components: boost player maximum health health regen projectile deflection etc Am I overthinking this? Should the shield just be a super component? I really think this is wrong answer. So if you think this is the way to go please explain. Should the shield be its own entity that tracks the location of the player? That might make it hard to implement the damage filtering. It also kinda blurs the lines between attached components and entities. Should the shield be a component that houses other components? I've never seen or heard of anything like this, but maybe it's common and I'm just not deep enough yet. Should the shield just be a set of components that get added to the player? Possibly with an extra component to manage the others, e.g. so they can all be removed as a group. (accidentally leave behind the damage reduction component, now that would be fun). Something else that's obvious to someone with more component experience?

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  • When to use SOAP over REST

    So, how does REST based services differ from SOAP based services, and when should you use SOAP? Representational State Transfer (REST) implements the standard HTTP/HTTPS as an interface allowing clients to obtain access to resources based on requested URIs. An example of a URI may look like this http://mydomain.com/service/method?parameter=var1&parameter=var2. It is important to note that REST based services are stateless because http/https is natively stateless. One of the many benefits for implementing HTTP/HTTPS as an interface is can be found in caching. Caching can be done on a web service much like caching is done on requested web pages. Caching allows for reduced web server processing and increased response times because content is already processed and stored for immediate access. Typical actions performed by REST based services include generic CRUD (Create, Read, Update, and Delete) operations and operations that do not require state. Simple Object Access Protocol (SOAP) on the other hand uses a generic interface in order to transport messages. Unlike REST, SOAP can use HTTP/HTTPS, SMTP, JMS, or any other standard transport protocols. Furthermore, SOAP utilizes XML in the following ways: Define a message Defines how a message is to be processed Defines the encoding of a message Lays out procedure calls and responses As REST aligns more with a Resource View, SOAP aligns more with a Method View in that business logic is exposed as methods typically through SOAP web service because they can retain state. In addition, SOAP requests are not cached therefore every request will be processed by the server. As stated before Soap does retain state and this gives it a special advantage over REST for services that need to preform transactions where multiple calls to a service are need in order to complete a task. Additionally, SOAP is more ideal for enterprise level services that implement standard exchange formats in the form of contracts due to the fact that REST does not currently support this. A real world example of where SOAP is preferred over REST can be seen in the banking industry where money is transferred from one account to another. SOAP would allow a bank to perform a transaction on an account and if the transaction failed, SOAP would automatically retry the transaction ensuring that the request was completed. Unfortunately, with REST, failed service calls must be handled manually by the requesting application. References: Francia, S. (2010). SOAP vs. REST. Retrieved 11 20, 2011, from spf13: http://spf13.com/post/soap-vs-rest Rozlog, M. (2010). REST and SOAP: When Should I Use Each (or Both)? Retrieved 11 20, 2011, from Infoq.com: http://www.infoq.com/articles/rest-soap-when-to-use-each

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  • Game editor integration with the engine?

    - by Daniel
    What I am trying to figure out is what is the best way to integrate the editor(level, effects, model, etc...) in the most effective way? Now the first thing I thought would be to create the game engine(*) extremely modular. For example I took the example of game states. You could have multiple game states that all have their own update() and draw() methods among others. Each game state class would inherit from a base GameState class. This allows for a more modular approach and a useful one at that. Now would the most efficient approach be to implement the editor along with the modular engine, or create two different designs for both the game, and editor? I thought to take the game state example and extend it to window states, and well could be used for a lot more systems. Is there a better implementation of this design(game state) for use in other systems used in the engine? *: Now I know the term game engine is sorta irrelevant, and misused in many situations. What I am referring to as the "game engine" is the combination of the systems that the game must interact with for short. Also this is more of a theory / design question than an implementation. Even though both mix, i'd rather like to have a more general idea on how the editor is built in an efficient way and still using the same engine code as what the game uses. Thanks, Daniel P.S If you need more clarification or extra bits just leave a comment.

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  • Examples of limitations in IT due to different bit length by design

    - by Alaudo
    I am teaching the course "Introduction in Programming" for the first-year students and would like to find interesting examples where the datatype size in bits, chosen by design, led to certain known restrictions or important values. Here are some examples: Due to the fact that the Bell teleprinter used 7-bit-code (later accepted as ASCII) until now have we often to encode attachments in electronic messages to contain only 7 bit data. Classical limitation of 32-bit address space leads to the 4Gb maximal RAM size available for 32-bit systems and 4Gb maximal file size in FAT32. Do you know some other interesting examples how the choice of the data type (and especially its binary length) influenced the modern IT world. Added after some discussion in comments: I am not going to teach how to overcome limitations. I just want them to know that 1 byte can hold the values from -127..0..+127 o 0..255, 2 bytes cover the range 0..65535 etc by proving examples they know from other sources, like the above-mentioned base64 encoding etc. We are just learning the basic datatypes and I am trying to find a good reference for "how large" these types are.

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  • How to design a character animation system?

    - by Andrea Benedetti
    I'm searching for suggestions and resources on the possible ways to design a character animation system. I mean a system built on top of the graphics engine (as graphics engine I use Ogre3D, that provide an animation layer), and in strict contact with the logic of the game. It's for a sports title, so the question is not easy. Edit: What I'm searching for are suggestions and resources about the action state mechines (or animation state machines), that is build on top of the animation pipeline already provided by the graphics engine. So, a state-driver animation interface for use by virtually all higher-level game code.

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  • What tools, libraries, or framework is needed to create a completely offline Javascript application?

    - by makerofthings7
    I am interested in creating a HTML application that can run as disconnected from the server as possible. Two examples of this include OWA in Exchange 2013 and to a lesser extent and the client available at www.ripple.com With the focus on OWA in Exchange 2013, what is needed to replicate the offline functionality available in a different application? A list technologies, frameworks, etc would be immensely helpful

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  • Use of Service Bus in a Pub-Sub Engine

    - by JoseK
    In one of our projects, we've built a Publisher - Subscriber Engine on Oracle Service Bus. The functionality being a series of events are published and subscribers (JMS queues) receive these whenever a new event is published. We are facing some technical issues now, performance-wise and hence an architectural review is underway. Now for my questions: Architecturally the ESB has to publish events into a DB and read from the DB which users wish to be notified, then push the event onto their respective queues. There is a high amount of DB interaction and the question is whether ESB should be having such high amount of interaction with the DB in the first place? Or should there have been some alternate component responsible for doing this. Alternately is there any non-DB approach in which we can store the events and subscribers? Where else can this application data be held within the ESB context?

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  • Reuse Business Logic between Web and API

    - by fesja
    We have a website and two mobile apps that connect through an API. All the platforms do the exactly same things. Right now the structure is the following: Website. It manages models, controllers, views for the website. It also executes all background tasks. So if a user create a place, everything is executed in this code. API. It manages models, controllers and return a JSON. If a user creates a place on the mobile app, the place is created here. After, we add a background task to update other fields. This background task is executed by the Website. We are redoing everything, so it's time to improve the approach. Which is the best way to reuse the business logic so I only need to code the insert/edit/delete of the place & other actions related in just one place? Is a service oriented approach a good idea? For example: Service. It has the models and gets, adds, updates and deletes info from the DB. Website. It send the info to the service, and it renders HTML. API. It sends info to the service, and it returns JSON. Some problems I have found: More initial work? Not sure.. It can work slower. Any experience? The benefits: We only have the business logic in one place, both for web and api. It's easier to scale. We can put each piece on different servers. Other solutions Duplicate the code and be careful not to forget anything (do tests!) DUplicate some code but execute background tasks that updates the related fields and executes other things (emails, indexing...) A "small" detail is we are 1.3 person in backend, for now ;)

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  • REST - Tradeoffs between content negotiation via Accept header versus extensions

    - by Brandon Linton
    I'm working through designing a RESTful API. We know we want to return JSON and XML for any given resource. I had been thinking we would do something like this: GET /api/something?param1=value1 Accept: application/xml (or application/json) However, someone tossed out using extensions for this, like so: GET /api/something.xml?parm1=value1 (or /api/something.json?param1=value1) What are the tradeoffs with these approaches? Is it best to rely on the accept header when an extension isn't specified, but honor extensions when specified? Is there a drawback to that approach?

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  • Is event sourcing ready for prime time?

    - by Dakotah North
    Event Sourcing was popularized by LMAX as a means to provide speed, performance scalability, transparent persistence and transparent live mirroring. Before being rebranded as Event Sourcing, this type of architectural pattern was known as System Prevalence but yet I was never familiar with this pattern before the LMAX team went public. Has this pattern proved itself in numerous production systems and therefore even conservative individuals should feel empowered to embrace this pattern or is event sourcing / system prevalence an exotic pattern that is best left for the fearless?

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  • SceneManagers as systems in entity system or as a core class used by a system?

    - by Hatoru Hansou
    It seems entity systems are really popular here. Links posted by other users convinced me of the power of such system and I decided to try it. (Well, that and my original code getting messy) In my project, I originally had a SceneManager class that maintained needed logic and structures to organize the scene (QuadTree, 2D game). Before rendering I call selectRect() and pass the x,y of the camera and the width and height of the screen and then obtain a minimized list containing only visible entities ordered from back to front. Now with Systems, originally in my first attempt my Render system required to get added all entities it should handle. This may sound like the correct approach but I realized this was not efficient. Trying to optimize It I reused the SceneManager class internally in the Renderer system, but then I realized I needed methods such as selectRect() in others systems too (AI principally) and make the SceneManager accessible globally again. Currently I converted SceneManager to a system, and ended up with the following interface (only relevant methods): /// Base system interface class System { public: virtual void tick (double delta_time) = 0; // (methods to add and remove entities) }; typedef std::vector<Entity*> EntitiesVector; /// Specialized system interface to allow query the scene class SceneManager: public System { public: virtual EntitiesVector& cull () = 0; /// Sets the entity to be used as the camera and replaces previous ones. virtual void setCamera (Entity* entity) = 0; }; class SceneRenderer // Not a system { vitual void render (EntitiesVector& entities) = 0; }; Also I could not guess how to convert renderers to systems. My game separates logic updates from screen updates, my main class have a tick() method and a render() method that may not be called the same times. In my first attempt renderers were systems but they was saved in a separated manager, updated only in render() and not in tick() like all other systems. I realized that was silly and simply created a SceneRenderer interface and give up about converting them to systems, but that may be for another question. Then... something does not feel right, isn't it? If I understood correctly a system should not depend on another or even count with another system exposing an specific interface. Each system should care only about its entities, or nodes (as optimization, so they have direct references to relevant components without having to constantly call the component() or getComponent() method of the entity).

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  • Using an actor model versus a producer-consumer model?

    - by hewhocutsdown
    I'm doing some early-stage research towards architecting a new software application. Concurrency and multithreading will likely play a significant part, so I've been reading up on the various topics. The producer-consumer model, at least how it is expressed in Java, has some surface similarities but appears to be deeply dissimilar to the actor model in use with languages such as Erlang and Scala. I'm having trouble finding any good comparative data, or specific reasons to use or avoid the one or the other. Is the actor model even possible with Java or C#, or do you have do use one of the languages built for the purpose? Is there a third way?

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  • How would you gather client's data on Google App Engine without using Datastore/Backend Instances too much?

    - by ruslan
    I'm relatively new to StackExchange and not sure if it's appropriate place to ask design question. Site gives me a hint "The question you're asking appears subjective and is likely to be closed". Please let me know. Anyway.. One of the projects I'm working on is online survey engine. It's my first big commercial project on Google App Engine. I need your advice on how to collect stats and efficiently record them in DataStore without bankrupting me. Initial requirements are: After user finishes survey client sends list of pairs [ID (int) + PercentHit (double)]. This list shows how close answers of this user match predefined answers of reference answerers (which identified by IDs). I call them "target IDs". Creator of the survey wants to see aggregated % for given IDs for last hour, particular timeframe or from the beginning of the survey. Some surveys may have thousands of target/reference answerers. So I created entity public class HitsStatsDO implements Serializable { @Id transient private Long id; transient private Long version = (long) 0; transient private Long startDate; @Parent transient private Key parent; // fake parent which contains target id @Transient int targetId; private double avgPercent; private long hitCount; } But writing HitsStatsDO for each target from each user would give a lot of data. For instance I had a survey with 3000 targets which was answered by ~4 million people within one week with 300K people taking survey in first day. Even if we assume they were answering it evenly for 24 hours it would give us ~1040 writes/second. Obviously it hits concurrent writes limit of Datastore. I decided I'll collect data for one hour and save that, that's why there are avgPercent and hitCount in HitsStatsDO. GAE instances are stateless so I had to use dynamic backend instance. There I have something like this: // Contains stats for one hour private class Shard { ReadWriteLock lock = new ReentrantReadWriteLock(); Map<Integer, HitsStatsDO> map = new HashMap<Integer, HitsStatsDO>(); // Key is target ID public void saveToDatastore(); public void updateStats(Long startDate, Map<Integer, Double> hits); } and map with shard for current hour and previous hour (which doesn't stay here for long) private HashMap<Long, Shard> shards = new HashMap<Long, Shard>(); // Key is HitsStatsDO.startDate So once per hour I dump Shard for previous hour to Datastore. Plus I have class LifetimeStats which keeps Map<Integer, HitsStatsDO> in memcached where map-key is target ID. Also in my backend shutdown hook method I dump stats for unfinished hour to Datastore. There is only one major issue here - I have only ONE backend instance :) It raises following questions on which I'd like to hear your opinion: Can I do this without using backend instance ? What if one instance is not enough ? How can I split data between multiple dynamic backend instances? It hard because I don't know how many I have because Google creates new one as load increases. I know I can launch exact number of resident backend instances. But how many ? 2, 5, 10 ? What if I have no load at all for a week. Constantly running 10 backend instances is too expensive. What do I do with data from clients while backend instance is dead/restarting? Thank you very much in advance for your thoughts.

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  • Materialized View vs POJO View based on Objects representing Oracle tables

    - by Zack Macomber
    I have about 12 Oracle tables that represent data that's being integrated from an external system into my web application. This data is going to be used in an informational and comparative manner for the clients using my web application. On one particular page of my web application, I need to combine data from 3 - 5 Oracle tables for display as an HTML table on the page. We are NOT currently using a framework (Apache Struts for instance) and we're not in a position to move this Java web application into one at this moment (I'm trying to get us there...). I am certainly not an architect, but I see one of two ways that I can effectively build this page (I know there are other ways, but these seem like they would be good ones...): 1. Create an Oracle Materialized View that represents what the HTML table should look like and then create a POJO based on the View that I can then integrate into my JSP. 2. Create POJOs that represent the Oracle tables themselves and then create another POJO that is the View used for the HTML table and then integrate that POJO into my JSP. To me, it seems the Materialized View would possibly offer quicker results which is always what we strive for in web applications. But, if I just create 12 POJOs that represent the Oracle tables and then build POJO Views off of those, I have the advantage of keeping all the code in one place for this and possibility for creating any number of different views and reusable components in my web application. Any thoughts on which one might be the better route? Or, maybe you know of an even better one?

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  • How can I save state from script in a multithreaded engine?

    - by Peter Ren
    We are building a multithreaded game engine and we've encountered some problems as described below. The engine have 3 threads in total: script, render, and audio. Each frame, we update these 3 threads simultaneously. As these threads updating themselves, they produce some tasks and put them into a public storage area. As all the threads finish their update, each thread go and copy the tasks for themselves one by one. After all the threads finish their task copying, we make the threads process those tasks and update these threads simultaneously as described before. So this is the general idea of the task schedule part of our engine. Ok, well, all the task schedule part work well, but here's the problem: For the simplest, I'll take Camera as an example: local oldPos = camera:getPosition() -- ( 0, 0, 0 ) camera:setPosition( 1, 1, 1 ) -- Won't work now, cuz the render thread will process the task at the beginning of the next frame local newPos = camera:getPosition() -- Still ( 0, 0, 0 ) So that's the problem: If you intend to change a property of an object in another thread, you have to wait until that thread process this property-changing message. As a result, what you get from the object is still the information in the last frame. So, is there a way to solve this problem? Or are we build the task schedule part in a wrong way? Thanks for your answers :)

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  • How do I create my own programming language and a compiler for it

    - by Dave
    I am thorough with programming and have come across languages including BASIC, FORTRAN, COBOL, LISP, LOGO, Java, C++, C, MATLAB, Mathematica, Python, Ruby, Perl, JavaScript, Assembly and so on. I can't understand how people create programming languages and devise compilers for it. I also couldn't understand how people create OS like Windows, Mac, UNIX, DOS and so on. The other thing that is mysterious to me is how people create libraries like OpenGL, OpenCL, OpenCV, Cocoa, MFC and so on. The last thing I am unable to figure out is how scientists devise an assembly language and an assembler for a microprocessor. I would really like to learn all of these stuff and I am 15 years old. I always wanted to be a computer scientist someone like Babbage, Turing, Shannon, or Dennis Ritchie. I have already read Aho's Compiler Design and Tanenbaum's OS concepts book and they all only discuss concepts and code in a high level. They don't go into the details and nuances and how to devise a compiler or operating system. I want a concrete understanding so that I can create one myself and not just an understanding of what a thread, semaphore, process, or parsing is. I asked my brother about all this. He is a SB student in EECS at MIT and hasn't got a clue of how to actually create all these stuff in the real world. All he knows is just an understanding of Compiler Design and OS concepts like the ones that you guys have mentioned (i.e. like Thread, Synchronization, Concurrency, memory management, Lexical Analysis, Intermediate code generation and so on)

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  • Is it convenient to use a XML/JSON generated based system? [closed]

    - by Marcelo de Assis
    One of my clients insists that we missed a requisite for the project(a little social network, using PHP + MySql), is that all queries are made from XML / JSON static files (using AJAX) and not directly from the database. Edit: The main reason, stated by client, is a way to economize bandwith. Even the file loading, has to be using AJAX, to avoid server side processing. We will still use a database to store and insert data. These XML / JSON files will be (re) generated whenever any data is changed by CMS or users. As the project was developed without this "technique", we'll have a lot of work ahead, so I would like to avoid that. I'm asking if it's convenient to use a XML generated based system, because I think a database is already "optimized" and secure to deal with a lot of data traffic. Other issue I'm afraid of, is a chance of conflict when a user is trying to read a XML/JSON which is being just generated.

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