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• I'm creating my own scalable, rapid prototyping web server. How should I design it?

  - by Mike Willliams

  I'm going to create my own web server that focuses on scalability, rapid prototyping and the use of JavaScript as the server's scripting language, much like node.js. It will use a Model-View-Controller design pattern so a web application can support more concurrent users just by adding hardware -- and not having to redesign the software. Basically, I'm aiming to produce a framework that allows for fast and easy development of cloud applications without the need to write lots of boiler plate code. I've got some questions about this... How hard will it be to put MySQL in the cloud? How could I go about implementing this and make the resulting product free? Will I have to write my own engine or modify an existing one, if I do what should I watch out for? To make this scalable I need to adjust from one server to hundreds of servers this creates the requirement for the servers to be load balancing, how should I do this? If I balance based on the work load per server I would need gateway to handle all the incoming requests. Is it the right idea to have all the servers check into the gateway and update there status. By having the servers run through a gateway if the gateway dies all the incoming requests are ignored. I'm thinking that having all the servers maintain a list of each other, or at least a few I could rebuild the list of servers and establish a new gateway. Is it worth it? Or should I have a backup gateway that could switch out? Should I let the user choose? How should I pick which server handles the database and which handles the page serving? Should I spread the database so that queries are preformed on multiple servers? Which would theoretically improve performance. The servers would need to mirror the database at least once so that if a server goes down the database isn't corrupted. So this brings up writing another question, should I broadcast SQL queries so that all the servers can take a bit of the work load? If I do it that way wouldn't a query clog up the network so that other queries couldn't be preformed? What are my alternatives? Finally, is there a free solution already out there that might need a little modification that suits my needs?

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• Class Design -- Multiple Calls from One Method or One Call from Multiple Methods?

  - by Andrew

  I've been working on some code recently that interfaces with a CMS we use and it's presented me with a question on class design that I think is applicable in a number of situations. Essentially, what I am doing is extracting information from the CMS and transforming this information into objects that I can use programatically for other purposes. This consists of two steps: Retrieve the data from the CMS (we have a DAL that I use, so this is essentially just specifying what data from the CMS I want--no connection logic or anything like that) Map the parsed data to my own [C#] objects There are basically two ways I can approach this: One call from multiple methods public void MainMethodWhereIDoStuff() { IEnumerable<MyObject> myObjects = GetMyObjects(); // Do other stuff with myObjects } private static IEnumerable<MyObject> GetMyObjects() { IEnumerable<CmsDataItem> cmsDataItems = GetCmsDataItems(); List<MyObject> mappedObjects = new List<MyObject>(); // do stuff to map the CmsDataItems to MyObjects return mappedObjects; } private static IEnumerable<CmsDataItem> GetCmsDataItems() { List<CmsDataItem> cmsDataItems = new List<CmsDataItem>(); // do stuff to get the CmsDataItems I want return cmsDataItems; } Multiple calls from one method public void MainMethodWhereIDoStuff() { IEnumerable<CmsDataItem> cmsDataItems = GetCmsDataItems(); IEnumerable<MyObject> myObjects = GetMyObjects(cmsDataItems); // do stuff with myObjects } private static IEnumerable<MyObject> GetMyObjects(IEnumerable<CmsDataItem> itemsToMap) { // ... } private static IEnumerable<CmsDataItem> GetCmsDataItems() { // ... } I am tempted to say that the latter is better than the former, as GetMyObjects does not depend on GetCmsDataItems, and it is explicit in the calling method the steps that are executed to retrieve the objects (I'm concerned that the first approach is kind of an object-oriented version of spaghetti code). On the other hand, the two helper methods are never going to be used outside of the class, so I'm not sure if it really matters whether one depends on the other. Furthermore, I like the fact that in the first approach the objects can be retrieved from one line-- most likely anyone working with the main method doesn't care how the objects are retrieved, they just need to retrieve the objects, and the "daisy chained" helper methods hide the exact steps needed to retrieve them (in practice, I actually have a few more methods but am still able to retrieve the object collection I want in one line). Is one of these methods right and the other wrong? Or is it simply a matter of preference or context dependent?

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• How to overcome shortcomings in reporting from EAV database?

  - by David Archer

  The major shortcomings with Entity-Attribute-Value database designs in SQL all seem to be related to being able to query and report on the data efficiently and quickly. Most of the information I read on the subject warn against implementing EAV due to these problems and the commonality of querying/reporting for almost all applications. I am currently designing a system where almost all the fields necessary for data storage are not known at design/compile time and are defined by the end-user of the system. EAV seems like a good fit for this requirement but due to the problems I've read about, I am hesitant in implementing it as there are also some pretty heavy reporting requirements for this system as well. I think I've come up with a way around this but would like to pose the question to the SO community. Given that typical normalized database (OLTP) still isn't always the best option for running reports, a good practice seems to be having a "reporting" database (OLAP) where the data from the normalized database is copied to, indexed extensively, and possibly denormalized for easier querying. Could the same idea be used to work around the shortcomings of an EAV design? The main downside I see are the increased complexity of transferring the data from the EAV database to reporting as you may end up having to alter the tables in the reporting database as new fields are defined in the EAV database. But that is hardly impossible and seems to be an acceptable tradeoff for the increased flexibility given by the EAV design. This downside also exists if I use a non-SQL data store (i.e. CouchDB or similar) for the main data storage since all the standard reporting tools are expecting a SQL backend to query against. Do the issues with EAV systems mostly go away if you have a seperate reporting database for querying? EDIT: Thanks for the comments so far. One of the important things about the system I'm working on it that I'm really only talking about using EAV for one of the entities, not everything in the system. The whole gist of the system is to be able to pull data from multiple disparate sources that are not known ahead of time and crunch the data to come up with some "best known" data about a particular entity. So every "field" I'm dealing with is multi-valued and I'm also required to track history for each. The normalized design for this ends up being 1 table per field which makes querying it kind of painful anyway. Here are the table schemas and sample data I'm looking at (obviously changed from what I'm working on but I think it illustrates the point well): EAV Tables Person ------------------- - Id - Name - ------------------- - 123 - Joe Smith - ------------------- Person_Value ------------------------------------------------------------------- - PersonId - Source - Field - Value - EffectiveDate - ------------------------------------------------------------------- - 123 - CIA - HomeAddress - 123 Cherry Ln - 2010-03-26 - - 123 - DMV - HomeAddress - 561 Stoney Rd - 2010-02-15 - - 123 - FBI - HomeAddress - 676 Lancas Dr - 2010-03-01 - ------------------------------------------------------------------- Reporting Table Person_Denormalized ---------------------------------------------------------------------------------------- - Id - Name - HomeAddress - HomeAddress_Confidence - HomeAddress_EffectiveDate - ---------------------------------------------------------------------------------------- - 123 - Joe Smith - 123 Cherry Ln - 0.713 - 2010-03-26 - ---------------------------------------------------------------------------------------- Normalized Design Person ------------------- - Id - Name - ------------------- - 123 - Joe Smith - ------------------- Person_HomeAddress ------------------------------------------------------ - PersonId - Source - Value - Effective Date - ------------------------------------------------------ - 123 - CIA - 123 Cherry Ln - 2010-03-26 - - 123 - DMV - 561 Stoney Rd - 2010-02-15 - - 123 - FBI - 676 Lancas Dr - 2010-03-01 - ------------------------------------------------------ The "Confidence" field here is generated using logic that cannot be expressed easily (if at all) using SQL so my most common operation besides inserting new values will be pulling ALL data about a person for all fields so I can generate the record for the reporting table. This is actually easier in the EAV model as I can do a single query. In the normalized design, I end up having to do 1 query per field to avoid a massive cartesian product from joining them all together.

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• How can I write classes that don't rely on "global" variables?

  - by Joel

  When I took my first programming course in university, we were taught that global variables were evil & should be avoided at all cost (since you can quickly develop confusing and unmaintainable code). The following year, we were taught object oriented programming, and how to create modular code using classes. I find that whenever I work with OOP, I use my classes' private variables as global variables, i.e., they can be (and are) read and modified by any function within the class. This isn't really sitting right with me, as it seems to introduce the same problems global variables had in languages like C. So I guess my question is, how do I stop writing classes with "global" variables? Would it make more sense to pretend I'm writing in a functional language? By this I mean having all functions take parameters & return values instead of directly modifying class variables. If I need to set any fields, I can just take the output of the function and assign it instead of having the function do it directly. This seems like it might make more maintainable code, at least for larger classes. What's common practice? Thanks!

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• Help with 2-part question on ASP.NET MVC and Custom Security Design

  - by JustAProgrammer

  I'm using ASP.NET MVC and I am trying to separate a lot of my logic. Eventually, this application will be pretty big. It's basically a SaaS app that I need to allow for different kinds of clients to access. I have a two part question; the first deals with my general design and the second deals with how to utilize in ASP.NET MVC Primarily, there will initially be an ASP.NET MVC "client" front-end and there will be a set of web-services for third parties to interact with (perhaps mobile, etc). I realize I could have the ASP.NET MVC app interact just through the Web Service but I think that is unnecessary overhead. So, I am creating an API that will essentially be a DLL that the Web App and the Web Services will utilize. The API consists of the main set of business logic and Data Transfer Objects, etc. (So, this includes methods like CreateCustomer, EditProduct, etc for example) Also, my permissions requirements are a little complicated. I can't really use a straight Roles system as I need to have some fine-grained permissions (but all permissions are positive rights). So, I don't think I can really use the ASP.NET Roles/Membership system or if I can it seems like I'd be doing more work than rolling my own. I've used Membership before and for this one I think I'd rather roll my own. Both the Web App and Web Services will need to keep security as a concern. So, my design is kind of like this: Each method in the API will need to verify the security of the caller In the Web App, each "page" ("action" in MVC speak) will also check the user's permissions (So, don't present the user with the "Add Customer" button if the user does not have that right but also whenever the API receives AddCustomer(), check the security too) I think the Web Service really needs the checking in the DLL because it may not always be used in some kind of pre-authenticated context (like using Session/Cookies in a Web App); also having the security checks in the API means I don't really HAVE TO check it in other places if I'm on a mobile (say iPhone) and don't want to do all kinds of checking on the client However, in the Web App I think there will be some duplication of work since the Web App checks the user's security before presenting the user with options, which is ok, but I was thinking of a way to avoid this duplication by allowing the Web App to tell the API not check the security; while the Web Service would always want security to be verified Is this a good method? If not, what's better? If so, what's a good way of implementing this. I was thinking of doing this: In the API, I would have two functions for each action: // Here, "Credential" objects are just something I made up public void AddCustomer(string customerName, Credential credential , bool checkSecurity) { if(checkSecurity) { if(Has_Rights_To_Add_Customer(credential)) // made up for clarity { AddCustomer(customerName); } else // throw an exception or somehow present an error } else AddCustomer(customerName); } public void AddCustomer(string customerName) { // actual logic to add the customer into the DB or whatever // Would it be good for this method to verify that the caller is the Web App // through some method? } So, is this a good design or should I do something differently? My next question is that clearly it doesn't seem like I can really use [Authorize ...] for determining if a user has the permissions to do something. In fact, one action might depend on a variety of permissions and the View might hide or show certain options depending on the permission. What's the best way to do this? Should I have some kind of PermissionSet object that the user carries around throughout the Web App in Session or whatever and the MVC Action method would check if that user can use that Action and then the View will have some ViewData or whatever where it checks the various permissions to do Hide/Show?

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• WinForm Design View Error

  - by Ramiz Uddin

  I'm getting the following error on form design: Hide Call Stack at EnvDTE80.CodeModel2.DotNetNameFromLanguageSpecific(String LanguageName) at Microsoft.VisualStudio.Design.Serialization.CodeDom.VSCodeDomParser.CodeTypeDeclarationFromCodeClass(CodeClass vsClass) at Microsoft.VisualStudio.Design.Serialization.CodeDom.VSCodeDomParser.OnNamespacePopulateTypes(Object sender, EventArgs e) at System.CodeDom.CodeNamespace.get_Types() at Microsoft.VisualStudio.Design.Serialization.CodeDom.VSCodeDomParser.Parse(TextReader codeStream) at Microsoft.VisualStudio.Design.Serialization.CodeDom.MergedCodeDomParser.System.CodeDom.Compiler.ICodeParser.Parse(TextReader stream) at System.CodeDom.Compiler.CodeDomProvider.Parse(TextReader codeStream) at Microsoft.VisualStudio.Shell.Design.Serialization.CodeDom.CodeDomDocDataAdapter.get_CompileUnit() at Microsoft.VisualStudio.Design.Serialization.CodeDom.VSCodeDomDesignerLoader.PerformLoad(IDesignerSerializationManager serializationManager) at System.ComponentModel.Design.Serialization.BasicDesignerLoader.BeginLoad(IDesignerLoaderHost host) Need help!

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• Working with PHP and MySQL - need a good and secure design with OO design

  - by Andrew

  I am new to PHP- first time developer. I am working on my web application and it is nearly done; nevertheless, most of my sql was done directly via code using direct mysql requests. This is the way I approached it: In classes_db.php I declared the db settings and created methods that I use to open and close DB connections. I declare those objects on my regular pages: class classes_db { public $dbserver = 'server; public $dbusername = 'user'; public $dbpassword = 'pass'; public $dbname = 'db'; function openDb() { $dbhandle = mysql_connect($this->dbserver, $this->dbusername, $this->dbpassword); if (!$dbhandle) { die('Could not connect: ' . mysql_error()); } $selected = mysql_select_db($this->dbname, $dbhandle) or die("Could not select the database"); return $dbhandle; } function closeDb($con) { mysql_close($con); } } On my regular page, I do this: <?php require 'classes_db.php'; session_start(); //create instance of the DB class $db = new classes_db(); //get dbhandle $dbhandle = $db->openDb(); //process query $result = mysql_query("update user set username = '" . $usernameFromForm . "' where iduser= " . $_SESSION['user']->iduser); //close the connection if (isset($dbhandle)) { $db->closeDb($dbhandle); } ?> My questions is: how to do it right and make it OO and secure? I know that I need incorporate prepared queries- how to do it the best way? Please provide some code

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• MVC - Cocoa interface - Cocoa Design pattern book

  - by Idan

  So I started reading this book: http://www.amazon.com/Cocoa-Design-Patterns-Erik-Buck/dp/0321535022 On chapter 2 it explains about the MVC design pattern and gives and example which I need some clarification to. The simple example shows a view with the following fields: hourlyRate, WorkHours, Standarthours , salary. The example is devided into 3 parts : View - contains some text fiels and a table (the table contains a list of employees' data). Controller - comprised of NSArrayController class (contains an array of MyEmployee) Model - MyEmployee class which describes an employee. MyEmployee class has one method which return the salary according to the calculation logic, and attributes in accordance with the view UI controls. MyEmployee inherits from NSManagedObject. Few things i'm not sure of : 1. Inside the MyEmplpyee class implemenation file, the calculation method gets the class attributes using sentence like " [[self valueForKey:@"hourlyRate"] floatValue];" Howevern, inside the header there is no data member named hourlyRate or any of the view fields. I'm not quite sure how does it work, and how it gets the value from the right view field. (does it have to be the same name as the field name in the view). maybe the conncetion is made somehow using the Interface builder and was not shown in the book ? and more important: 2. how does it seperate the view from the model ? let's say ,as the book implies might happen, I decide one day to remove one of the fields in the view. as far as I understand, that means changing the way the salary method works in MyEmplpyee (cause we have one field less) , and removing one attribute from the same calss. So how is that separate the View from the Model if changing one reflect on the other ? I guess I get something wrong... Any comments ? Thanks

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• Global User Experience Research: Mobile

  - by ultan o'broin

  A shout out to the usableapps.oracle.com blog article Going Native to Understand Mobile Workers. Oracle is a global company and with all that revenue coming from outside the US, international usability research is essential. So read up about how the Applications User Experience team went about this important user-centered ethnographic research. Personalization is king in the mobile space. Going native is a great way to uncover exactly what users want as they work and use their mobile devices, but you need to do it worldwide!

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• Design Patterns Recommendation for Filtering Option

  - by Tarik

  Hi people, I am thinking to create a filter object which filters and delete everything like html tags from a context. But I want it to be independent which means the design pattern I can apply will help me to add more filters in the future without effecting the current codes. I thought Abstract Factory but it seems it ain't gonna work out the way I want. So maybe builder but it looks same. I don't know I am kinda confused, some one please recommend me a design pattern which can solve my problem but before that let me elaborate the problem a little bit. Lets say I have a class which has Description field or property what ever. And I need filters which remove the things I want from this Description property. So whenever I apply the filter I can add more filter in underlying tier. So instead of re-touching the Description field, I can easily add more filters and all the filters will run for Description field and delete whatever they are supposed to delete from the Description context. I hope I could describe my problem. I think some of you ran into the same situation before. Thanks in advance...

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• iPhone User Interface Design

  - by Blaenk

  Hey guys, I've just had a nagging question for a while regarding iPhone app user interfaces. For example, consider WeightBot's User Interface. I am wondering, how are most of these user interfaces created? In general, of course. Is there a way to simply design controls (that is, the images) in a program like Photoshop, then use that 'skin' for controls in UIKit? I realize that there are some controls that are probably created by the programmer (custom controls), but I'm referring to the ready-made ones that come in UIKit. In other words, is the concept similar to 'splicing' web site designs? Where a designer draws out the design of the website in something like Photoshop, and then it is cut up into pieces which can be applied to form the actual website? I know this can be done for UIButtons, can this also be done for other controls, and is this how it is usually done? Or perhaps this is done with Core Animation? I've heard this from time to time, so does this mean that the User Interfaces are 'hard-coded'? Or is Core Animation only use for the 'effects', such as applying the glowing effect to the numbers in WeightBot? If there are any resources you can point me to I would really appreciate it. Thanks!

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• Global Webcast: Increase Pharmaceutical Sales Effectiveness

  - by charles.knapp

  See a next-generation approach to Pharmaceutical sales challenges! • Increase the quality of sales interactions with enhanced call planning and eDetailing • Improve sample management with electronic signature storage and inventory tracking on the go • Increase marketing effectiveness with closed loop marketing and personalized content delivery Watch as senior vice president of CRM, Anthony Lye, and director of life sciences product strategy, Piers Evans, provide the first public look at Oracle's new Pharmaceutical Sales On The Go solution, powered by Oracle CRM On Demand Release 17 -- Life Sciences Edition. Register now for this informative GLOBAL webcast on March 31, 9 AM PDT/4 PM GMT.

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• “if” statement vs OO Design - 2

  - by hilal

  I encountered similar problem “if” statement vs OO Design - 1 but it is slightly different. Here is the problem that open the popup (different objects/popups) onValueChange of listbox Popup1 p1; // different objects Popup2 p2; // different objects Popup3 p3; ... listbox.add("p1"); listbox.add("p2"); listbox.add("p3"); ... listbox.addChangeHandler() { if(getSelectedItem().equals("p1")){ p1 = new Popup1(); p1.show(); } else if() {...} .... } I don't want to write "if" that if p1 then p1 = new Popup1(); p1.center(); How I can handle this situation? Any design-pattern? Here is my solution but it is so costly map() { map.put("p1", new Popup1()); map.put("p2", new Popup2()); map.put("p3", new Popup3()); } onValueChange() { map.get(selectedItem).show(); } One drawback is initialization all the popups. but it is require only when valueChange

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• CVE-2011-3192 and CVE-2011-0419 affect Oracle Secure Global Desktop

  - by chandan

  CVE DescriptionCVSSv2 Base ScoreComponentProduct and Resolution CVE-2011-0419 Resource Management Errors vulnerability 4.3 Apache HTTP Server Oracle Secure Global Desktop 4.62 CVE-2011-3192 Resource Management Errors vulnerability 7.8 This notification describes vulnerabilities fixed in third-party components that are included in Sun's product distribution.Information about vulnerabilities affecting Oracle Sun products can be found on Oracle Critical Patch Updates and Security Alerts page.

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• Correct OOP design without getters?

  - by kane77

  I recently read that getters/setters are evil and I have to say it makes sense, yet when I started learning OOP one of the first things I learned was "Encapsulate your fields" so I learned to create class give it some fields, create getters, setters for them and create constructor where I initialize these fields. And every time some other class needs to manipulate this object (or for instance display it) I pass it the object and it manipulate it using getters/setters. I can see problems with this approach. But how to do it right? For instance displaying/rendering object that is "data" class - let's say Person, that has name and date of birth. Should the class have method for displaying the object where some Renderer would be passed as an argument? Wouldn't that violate principle that class should have only one purpose (in this case store state) so it should not care about presentation of this object. Can you suggest some good resources where best practices in OOP design are presented? I'm planning to start a project in my spare time and I want it to be my learning project in correct OOP design..

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• First-Global-Teach for the Oracle Imaging and Process Management 11g: Administration: San Francisco

  - by stephen.schleifer

  First-Global-Teach for the Oracle Imaging and Process Management 11g: Administration: San Francisco | June 23-25 This course enables participants to use Oracle Imaging and Process Management (I/PM) 11g to access, track, and annotate documents. In addition, they also get an overview of the product architecture of Oracle I/PM running on Oracle WebLogic Server.The course also delves into administration tasks such as security permissions, configuration such as creating BPEL connections, and procedures for creating applications, searches, and input mappings. Customer and partners can register by looking up the course (#D61575GC10) on http://education.oracle.com

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• Best Practice, objects design ASP.NET MVC

  - by DoomStone

  Hello Stackoverflow I have a code design question that have been torbeling me for a while, you see I’m doing a refactoring of my website Cosplay Denmark, a site where cospalyers can upload images of them self in their costumes. The original site was done in php, Zend MVC, but my refactoring is being done in ASP.NET MVC 2. If you take the site http://www.cosplaydanmark.dk/Costumes/ (You can switch to English in the left column (Sprog)) Here you see a list of all the anime’s we have on the site with images, we show the name, how many different characters and how many images there are under this anime. http://www.cosplaydanmark.dk/Costumes/Bleach If you click on an anime will you get a list of characters within the given anime which we have images in, here do we show the character name, how many galleries and how many images. http://www.cosplaydanmark.dk/Costumes/Bleach/Ichigo_Kurosaki/ If you click on the character name, will you get a list of the galleries under the given character in the given anime. Here we have some information about the gallery, such as image count. http://www.cosplaydanmark.dk/Costumes/Bleach/Ichigo_Kurosaki/Admi/ Should you click the gallery do you get a list of the images in the gallery. My database look like this at the moment. As you can might imagine there are a lot of different query’s to create the site, on the first site I need to do a select on the on the “animes” table and for each result, I need to do a count select on characters and galleries. My plan to create this will be one of the following Where the IList, would be a lazy load list. But I can’t decide what would be the best solution for this would be, also if there is a better way of doing this. My priority is to have good performance with a minimum lose of features and code upkeep. I’m using a service pattern with a linq to sql repository. My design is not absolute, I’m willing to change it if it could increase performance :D I hope that I have describe my question good enough for you to understand what I mean, but ask away if there are anything I have missed.

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• C# Item system design approach, should I use abstract classes, interfaces or virutals?

  - by vexe

  I'm working on a Resident Evil 1/2/3/0/Remake type of game. Currently I've done a big part of the inventory system (here's a link if you wanna see my inventory, pretty outdated, added a lot of features and made a lot of enhancements) Now I'm thinking about how to approach the items system, If you've played any Resident Evil game or any of its likes you should be familiar with what I'm trying to achieve. Here's a very simple category I made for the items: So you have different items, with different operations you could perform on them, there are usable items that you could use, like for example herbs and first aid kits that 'using' them would affect your health, keys to unlock doors, and equipable items that you could 'equip' like weapons. Also, you can 'combine' two items together to get new one, like for example mixing a green and red herb would give you a new type of herb, or combining a lighter with a paper, would give you a burnt paper, or ammo with a gun, would reload the gun or something. etc. You know the usual RE drill. Not all items are 'transformable', in that, for example: lighter + paper = burnt paper (it's the paper that 'transforms' to burnt paper and not the lighter, the lighter is not transformable it will remain as it is) green herb + red herb = newHerb1 (both herbs will vanish and transform to this new type of herb) ammo + gun = reload gun (ammo state will remain as it is, it won't change but it will just decrease, nothing will happen to the gun it just gets reloaded) Also a key note to remember is that you can't just combine items randomly, each item has a 'mating' item(s). So to sum up, different items, and different operations on them. The question is, how to approach this, design-wise? I've been learning about interfaces, but it just doesn't quite get into my head, I mean, why not just use classes with the good old inheritance? I know the technical details of interfaces and that the cool thing about them is that they don't require an inheritance chain, but I just can't see how to use them properly, that is, if they were the right thing to use here. So should I go with just classes and inheritance? just like in the tree I showed you? or should I think more about how to use interfaces? (IUsable, IEquipable, ITransformable) - why not just use classes UsableItem, Equipable item, TransformableItem? I want something that won't give me headaches in the long run, something resilient/flexible to future changes. I'm OK using classes, but I smell something better here. The way I'm thinking is to possibly use both inheritance and interfaces, so that you have a branch like this: item - equipable - weapon. but then again, the weapon has methods like 'reload' 'examine' 'equip' some of them 'combine' so I'm thinking to make weapon implement ICombinable?... not all items get used the same way, using herbs will increase your health, using a key will open a door, so IUsable maybe? Should I use a big database (XML for example) for all the items, items names, mates, nRowsReq, nColsReq, etc? Thanks so much for your answers in advanced, note that demo 3 is coming after I'm done with items :D

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• Java - Is this a bad design pattern?

  - by Walter White

  Hi all, In our application, I have seen code written like this: User.java (User entity) public class User { protected String firstName; protected String lastName; ... getters/setters (regular POJO) } UserSearchCommand { protected List<User> users; protected int currentPage; protected int sortColumnIndex; protected SortOder sortOrder; // the current user we're editing, if at all protected User user; public String getFirstName() {return(user.getFirstName());} public String getLastName() {return(user.getLastName());} } Now, from my experience, this pattern or anti-pattern looks bad to me. For one, we're mixing several concerns together. While they're all user-related, it deviates from typical POJO design. If we're going to go this route, then shouldn't we do this instead? UserSearchCommand { protected List<User> users; protected int currentPage; protected int sortColumnIndex; protected SortOder sortOrder; // the current user we're editing, if at all protected User user; public User getUser() {return(user);} } Simply return the user object, and then we can call whatever methods on it as we wish? Since this is quite different from typical bean development, JSR 303, bean validation doesn't work for this model and we have to write validators for every bean. Does anyone else see anything wrong with this design pattern or am I just being picky as a developer? Walter

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• Database design for invoices, invoice lines & revisions

  - by FreshCode

  I'm designing the 2nd major iteration of a relational database for a franchise's CRM (with lots of refactoring) and I need help on the best database design practices for storing job invoices and invoice lines with a strong audit trail of any changes made to each invoice. Current schema Invoices Table InvoiceId (int) // Primary key JobId (int) StatusId (tinyint) // Pending, Paid or Deleted UserId (int) // auditing user Reference (nvarchar(256)) // unique natural string key with invoice number Date (datetime) Comments (nvarchar(MAX)) InvoiceLines Table LineId (int) // Primary key InvoiceId (int) // related to Invoices above Quantity (decimal(9,4)) Title (nvarchar(512)) Comment (nvarchar(512)) UnitPrice (smallmoney) Revision schema InvoiceRevisions Table RevisionId (int) // Primary key InvoiceId (int) JobId (int) StatusId (tinyint) // Pending, Paid or Deleted UserId (int) // auditing user Reference (nvarchar(256)) // unique natural string key with invoice number Date (datetime) Total (smallmoney) Schema design considerations 1. Is it sensible to store an invoice's Paid or Pending status? All payments received for an invoice are stored in a Payments table (eg. Cash, Credit Card, Cheque, Bank Deposit). Is it meaningful to store a "Paid" status in the Invoices table if all the income related to a given job's invoices can be inferred from the Payments table? 2. How to keep track of invoice line item revisions? I can track revisions to an invoice by storing status changes along with the invoice total and the auditing user in an invoice revision table (see InvoiceRevisions above), but keeping track of an invoice line revision table feels hard to maintain. Thoughts? 3. Tax How should I incorporate sales tax (or 14% VAT in SA) when storing invoice data?

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• Database design for credit based purchases

  - by FreshCode

  I need an elegant way to implement credit-based purchases for an online store with a small variety of products which can be purchased using virtual credit or real currency. Alternatively, products could only be priced in credits. Previous work I have implemented credit-based purchasing before using different product types (eg. Credit, Voucher or Music) with post-order processing to assign purchased credit to users in the form of real currency, which could subsequently be used to discount future orders' charge totals. This worked fairly well as a makeshift solution, but did not succeed in disconnecting the virtual currency from the real currency, which is what I'd like to do, since spending credits is psychologically easier for customers than spending real currency. Design I need guidance on designing the database correctly with support for the simultaneous bulk purchase of credits at a discount along with real currency products. Alternatively, should all products be priced in credits and only credit have a real currency value? Existing Database Design Partial Products table: ProductId Title Type UnitPrice SalePrice Partial Orders table: OrderId UserId (related to Users table, not shown) Status Value Total Partial OrderItems table (similar to CartItems table): OrderItemId OrderId (related to Orders table) ProductId (related to Products table) Quantity UnitPrice SalePrice Prospective UserCredits table: CreditId UserId (related to Users table, not shown) Value (+/- value. Summed over time to determine saldo.) Date I'm using ASP.NET MVC and LINQ-to-SQL on a SQL Server database.

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• Database design for sharing photos site?

  - by javaLearner.java

  I am using php and mysql. If I want to do a sharing photos website, whats the best database design for upload and display photos. This is what I have in mind: domain: |_> photos |_> user Logged in user will upload photo in [http://www.domain.com/user/upload.php] The photos are stored in filesystems, and the path-to-photos stored in database. So, in my photos folder would be like: photos/userA/subfolders+photos, photos/userB/subfolders+photos, photos/userC/subfolders+photos etc Public/others people may view his photo in: [http://www.domain.com/photos/user/?photoid=123] where 123 is the photoid, from there, I will query from database to fetch the path and display the image. My questions: Whats the best database design for photo-sharing website (like flickr)? Will there be any problems if I keep creating new folder in "photos" folder. What if hundreds of thousands users registered? Whats the best practices What size of photos should I keep? Currently I only stored thumbnail (100x100) and (max) 1600x1200 px photos. What others things I should take note when developing photos-sharing website?

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• Easy way to set up global API hooks

  Discover an easy way to set up system-wide global API hooks using AppInit_DLLs registry key for DLL injection and Mhook library for API hooking. To illustrate this technique we will show how to easily hide calc.exe from the list of running processes.

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• Android Multiple Handlers Design Question

  - by Soumya Simanta

  This question is related to an existing question I asked. I though I'll ask a new question instead of replying back to the other question. Cannot "comment" on my previous question because of a word limit. Marc wrote - I've more than one Handlers in an Activity." Why? If you do not want a complicated handleMessage() method, then use post() (on Handler or View) to break the logic up into individual Runnables. Multiple Handlers makes me nervous. I'm new to Android. Is having multiple handlers in a single activity a bad design ? I'm new to Android. My question is - is having multiple handlers in a single activity a bad design ? Here is the sketch of my current implementation. I've a mapActivity that creates a data thread (a UDP socket that listens for data). My first handler is responsible for sending data from the data thread to the activity. On the map I've a bunch of "dynamic" markers that are refreshed frequently. Some of these markers are video markers i.e., if the user clicks a video marker, I add a ViewView that extends a android.opengl.GLSurfaceView to my map activity and display video on this new vide. I use my second handler to send information about the marker that the user tapped on ItemizedOverlay onTap(int index) method. The user can close the video view by tapping on the video view. I use my third handler for this. I would appreciate if people can tell me what's wrong with this approach and suggest better ways to implement this. Thanks.

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• Movies recommendation engine conceptual database design

  - by Supyxy

  I am working at an movie recommendations engine and i'm facing a DB design issue. My actual database looks like this: MOVIES [ID,TITLE] KEYWORDS_TABLE [ID,KEY_ID] - where ID is Foreign Key for MOVIES.id and KEY_ID is a key for a text keywords table This is not the entire DB, but i showed here what's important for my problem. I have about 50,000 movies and about 1,3 milion keywords correlations, and basically my algorithm consists in extracting all the who have the same keywords with a given movie, then ordering them by the number of keywords correlations. For example i looked for a movie similar to 'Cast away' and it returned 'Six days and six nights' because it had the most keywords correlations (4 keywords): Island Airplane crash Stranded Pilot The algorithm is based on more factors, but this one is the most important and the most difficult for the approach. Basically what i do now is getting all the movies that have at least one keyword similar to the given movie and then ordering them by other factors which are not important for a moment. There wouldn't be any problem if there weren't so many records, a query lasts in many cases up to 10-20 seconds and some of them return even over 5000 movies. Someone already helped me on here (thanks Mark Byers) with optimizing the query but that's not enough because it takes too longer SELECT DISTINCT M.title FROM keywords_table K1 JOIN keywords_table K2 ON K2.key_id = K1.key_id JOIN movies M ON K2.id = M.id WHERE K1.id = 4 So i thought it would be better if i pre-made those lists with movies recommendations for each movie, but i'm not sure how to design the tables.. whatever is it a good idea or how would you take this approach?

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