Search Results

Search found 6209 results on 249 pages for 'composite pattern'.

Page 184/249 | < Previous Page | 180 181 182 183 184 185 186 187 188 189 190 191  | Next Page >

• Data access strategy for a site like SO - sorted SQL queries and simultaneous updates that affect th

  - by Kaleb Brasee

  I'm working on a Grails web app that would be similar in access patterns to StackOverflow or MyLifeIsAverage - users can vote on entries, and their votes are used to sort a list of entries based on the number of votes. Votes can be placed while the sorted select queries are being performed. Since the selects would lock a large portion of the table, it seems that normal transaction locking would cause updates to take forever (given enough traffic). Has anyone worked on an app with a data access pattern such as this, and if so, did you find a way to allow these updates and selects to happen more or less concurrently? Does anyone know how sites like SO approach this? My thought was to make the sorted selects dirty reads, since it is acceptable if they're not completely up to date all of the time. This is my only idea for possibly improving performance of these selects and updates, but I thought someone might know a better way.

  Read the article

• Efficient persistent storage for simple id to table of values map for java

  - by wds

  I need to store some data that follows the simple pattern of mapping an "id" to a full table (with multiple rows) of several columns (i.e. some integer values [u, v, w]). The size of one of these tables would be a couple of KB. Basically what I need is to store a persistent cache of some intermediary results. This could quite easily be implemented as simple sql, but there's a couple of problems, namely I need to compress the size of this structure on disk as much as possible. (because of amount of values I'm storing) Also, it's not transactional, I just need to write once and simply read the contents of the entire table, so a relational DB isn't actually a very good fit. I was wondering if anyone had any good suggestions? For some reason I can't seem to come up with something decent atm. Especially something with an API in java would be nice.

  Read the article

• Can we you the attached properties in C# class library?

  - by Manas Agarwal

  Hi I have implemented the Observer Pattern with lazy load. The class that requests the data from the database is a singleton class. Now I am able to load the data from one database (located in one datacenter) very easily. But I need to get the data from other data centers too and display on the same UI. I can somehow pass the address of second data center and fetch the data from there also. But once I will get the data from second data center, it will be added to earlier list only. So later it will be thought for me to distinguish between the data. So I thought of attaching a property with the result set, so that while displaying the output I can show the data for both the data centers separately but on the same UI. I thought of attached property as an option where I can attach the data center name with the list of the data obtained. How is it possible to do in C#? Thanks Manas

  Read the article

• Partitioning requests in code among several servers

  - by Jacques René Mesrine

  I have several forum servers (what they are is irrelevant) which stores posts from users and I want to be able to partition requests among these servers. I'm currently leaning towards partitioning them by geographic location. To improve the locality of data, users will be separated into regions e.g. North America, South America and so on. Is there any design pattern on how to implement the function that maps the partioning property to the server, so that this piece of code has high availability and would not become a single point of failure ? f( Region ) -> Server IP

  Read the article

• Thread used for ServiceConnection callback (Android)

  - by Jannick

  Hi I'm developing an activity that binds to a local service (in onCreate of the activity): bindService(new Intent(this, CommandService.class), svcConn, BIND_AUTO_CREATE); I would like to be able to call methods through the IBinder in my lifecycle methods, but can not be sure that onServiceConnected have been called prior to these. I'm thinking of handling this by adding a queue of sorts in the ServiceConnection implementation, so that the method calls (Command pattern) will be executed once the connection is established. My questions are then: Is this stupid, any better ways? :) Are there any specification for which thread will be used to execute the ServiceConnection callbacks? More to the point, do I need to worry about synchronizing a queue datastructure? Edit - something like: public void onServiceConnected(ComponentName name, IBinder service) { dispatchService = (DispatchAsync)service; for(ExecutionTask task : queue){ dispatchService.execute(task.getCommand(), task); } }

  Read the article

• Is it possible to listen to relational database update?

  - by Morgan Cheng

  Is it possible to listen to relation database update? For example, my web app want to send data update to client through Comet technology. I can have the program to poll the database periodically, but that would not be performant and scalable. If app can hood to a "event handler" of database, then app can get notification every time given database table data is updated. This sounds more promising, but I didn't find any concrete example for it. This is listener pattern. Does common relational database support such feature?

  Read the article

• Why use hashing to create pathnames for large collections of files?

  - by Stephen

  Hi, I noticed a number of cases where an application or database stored collections of files/blobs using a has to determine the path and filename. I believe the intended outcome is a situation where the path never gets too deep, or the folders ever get too full - too many files (or folders) in a folder making for slower access. EDIT: Examples are often Digital libraries or repositories, though the simplest example I can think of (that can be installed in about 30s) is the Zotero document/citation database. Why do this? EDIT: thanks Mat for the answer - does this technique of using a hash to create a file path have a name? Is it a pattern? I'd like to read more, but have failed to find anything in the ACM Digital Library

  Read the article

• Using NSThread to solve waiting for image from URL on the iPhone

  - by james.ingham

  So I have the following code in a method which I want to set a UIImageView image to that of one from an online source: [NSThread detachNewThreadSelector:@selector(loadImage) toTarget:self withObject:nil]; Then in the method called by the thread I have this: - (void) loadImage { NSURL *url = [NSURL URLWithString:logoPath]; // logoPath is an NSString with path details NSData *data = [NSData dataWithContentsOfURL:url]; logoImage.image = [UIImage imageWithData:data]; } This works great however I get many warnings within the Debugger Console along the lines of: 2010-05-10 14:30:14.052 ProjectTitle[2930:633f] * _NSAutoreleaseNoPool(): Object 0x169d30 of class NSHTTPURLResponse autoreleased with no pool in place - just leaking This occurs many times each time I call the new thread and then eventually, under no pattern, after calling a few of these threads I get the classic 'EXC_BAD_ACCESS' run-time error. I understand that this is happening because I'm not retaining the object but how can I solve this with the code in 'loadImage' shown above? Thanks

  Read the article

• Is it a bad idea to use the new Dynamic Keyword as a replacement switch statement?

  - by WeNeedAnswers

  I like the new Dynamic keyword and read that it can be used as a replacement visitor pattern. It makes the code more declarative which I prefer. Is it a good idea though to replace all instances of switch on 'Type' with a class that implements dynamic dispatch. class VistorTest { public string DynamicVisit(object obj) { return Visit((dynamic)obj); } private string Visit(string str) { return "a string was called with value " + str; } private string Visit(int value) { return "an int was called with value " + value; } }

  Read the article

• how to open many files simultaneously for reading in c

  - by monkeyking

  I'm trying to port some of my c++ code into c. I have the following construct class reader{ private: FILE *fp; alot_of_data data;//updated by read_until() method public: reader(const char*filename) read_until(some conditional dependent on the contents of the file, and the arg supplied) } Im then instantiating hundreds of these object and iterate over them using several 'read_until()' for each file until allfiles is at eof. I'm failing to see any clever way to do this in c, the only solution I can come up with is making an array of FILE pointers, and do the same with all the private member data from my class. But this seems very messy, can I implement the functionality of my class as a function pointer, or anything better, I think I'm missing a fundamental design pattern? The files are way to big to have all in memory, so reading everything from every file is not feasible Thanks

  Read the article

• JSF tags not being rendered as HTML

  - by Toto

  I'm following the Java EE firstcup tutorial using Netbeans and Glassfish. When I execute the JSF web tier I've been instructed to code, the browser gets the same JSF markup coded in the .xhtml file, and the tags are not rendered as HTML tags. I know this by using the view source code in my browser. For example, for this code: <html xmlns="http://www.w3.org/1999/xhtml" xmlns:f="http://java.sun.com/jsf/core" xmlns:h="http://java.sun.com/jsf/html"> <h:head> <title>Page title here</title> </h:head> <h:body> <h2> <h:outputText value="#{bundle.WelcomeMessage}" /> </h2> </h:body> </html> The browser should get something like: <html ...> <head> <title>Page title here</title> </head> <body> <h2> the welcome message goes here </h2> </body> </html> Right? Well, my browser is getting jsf code (the first piece of code above) and not the html code (the second piece of code above). It seems to be a configuration problem in netbeans or glassfish but don't know what. Any ideas? This is my web.xml file: <?xml version="1.0" encoding="UTF-8"?> <web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"> <context-param> <param-name>javax.faces.PROJECT_STAGE</param-name> <param-value>Development</param-value> </context-param> <servlet> <servlet-name>Faces Servlet</servlet-name> <servlet-class>javax.faces.webapp.FacesServlet</servlet-class> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>Faces Servlet</servlet-name> <url-pattern>/firstcup/*</url-pattern> </servlet-mapping> <session-config> <session-timeout> 30 </session-timeout> </session-config> <welcome-file-list> <welcome-file>greetings.xhtml</welcome-file> </welcome-file-list> </web-app> This is my faces-config.xml file: <?xml version='1.0' encoding='UTF-8'?> <!-- =========== FULL CONFIGURATION FILE ================================== --> <faces-config version="2.0" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-facesconfig_2_0.xsd"> <application> <resource-bundle> <base-name>firstcup.web.WebMessages</base-name> <var>bundle</var> </resource-bundle> <locale-config> <default-locale>en</default-locale> <supported-locale>es</supported-locale> </locale-config> </application> <navigation-rule> <from-view-id>/greetings.xhtml</from-view-id> <navigation-case> <from-outcome>success</from-outcome> <to-view-id>/response.xhtml</to-view-id> </navigation-case> </navigation-rule> </faces-config> Moreover: The url I'm entering in the browser is http://localhost:8081/firstcup/ but I've also tried: http://localhost:8081/firstcup/greetings.xhtml I've checked Glassfish logs and there's no information about not being able to load FacesServlet

  Read the article

• Do I still have to implement a singleton class by hand in .net, even when using .Net4.0?

  - by Hamish Grubijan

  Once the singleton pattern is understood, writing subsequent singleton classes in C# is a brainless exercise. I would hope that the framework would help you by providing an interface or a base class to do that. Here is how I envision it: public sealed class Schablone : ISingleton<Schablone> { // Stuff forced by the interface goes here // Extra logic goes here } Does what I am looking for exist? Is there some syntactic sugar for constructing a singleton class - whether with an interface, a class attribute, etc.? Can one write a useful and bullet-proof ISingleton themselves? Care to try? Thanks!

  Read the article

• Configuration and Model-View

  - by HH

  I am using the Model-View pattern on a small application I'm writing. Here's the scenario: The model maintains a list of directories from where it can extract the data that it needs. The View has a Configuration or a Setting dialog where the user can modify this list of directories (the dialog has a JList displaying the list in addition to add and remove buttons). I need some advice from the community: The View needs to communicate these changes to the model. I thought first of adding to the model these methods: addDirectory() and removeDirectory(). But I am trying to limit the number of methods (or channels) that the View can use to communicate with and manipulate the model. Is there any good practice for this? Thank you.

  Read the article

• Architecting a generic search result web control

  - by Bartek Tatkowski

  In a project I'm currently working for we've stumbled upon the need for several kinds of search results presentation controls. The search result are similar, but not identical. For example, in the "office search" result we might want to present the office name and location, while in the "document search" could contain document name, author and publishing date. These fields should be sortable. My current strategy is to employ the Factory pattern and do something like this: ISearchResult officeResults = SearchResultFactory.CreateOfficeSearchResults(data); ISearchResult documentResults = SearchResultFactory.CreateDocumentSearchResults(data); The problem is: I don't know how to implement the markup code. Should I just do Controls.Add(officeResults); in the containing page? Or is there some ASPX trickery to create generic web controls? Or maybe I'm overthinking this and just should create five classes? ;)

  Read the article

• Unit Testing User Interface. What is an effective way ?

  - by pierocampanelli

  I have an accounting & payroll client/server application where there are several input form with complex data validation rules. I am finding an effective way to perform unit testing of user interface. For complex validation rules I mean: "Disable button X if I Insert a value in textfield Y" "Enable a combobox if I insert a value in a textfield" ...... ...... Most promising pattern i have found is suggested by M. Fowler (http://martinfowler.com/eaaDev/ModelViewPresenter.html). Have you any experience about Unit Testing of User Interface? As technology stack I am using: .NET 3.5 & Windows Forms Widget Library.

  Read the article

• VS 2010 Entity Repository Error Class member EntityBase.id is unmapped.

  - by Steve

  In my project I have it set up so that all the tables in the DB has the property "id" and then I have the entity objects inherit from the EntityBase class using a repository pattern. I then set the inheritance modifier for "id" property in the dbml file o/r designer to "overrides" Public MustInherit Class EntityBase MustOverride Property id() As Integer End Class Public MustInherit Class RepositoryBase(Of T As EntityBase) Protected _Db As New DataClasses1DataContext Public Function GetById(ByVal Id As Integer) As T Return (From a In _Db.GetTable(Of T)() Where a.id = Id).SingleOrDefault End Function End Class Partial Public Class Entity1 Inherits EntityBase End Class Public Class TestRepository Inherits RepositoryBase(Of Entity1) End Class the line Return (From a In _Db.GetTable(Of T)() Where a.id = Id).SingleOrDefault however produces the error "Class member EntityBase.id is unmapped" when i use VS 2010 using the 4.0 framework but I never received that error with the old one. Any help would be greatly appreciated. Thanks in advance.

  Read the article

• URL rewrite module for IIS7

  - by Learner

  I am trying to test if the redirect that I wrote works or not. If I do IISReset the redirect does not work. But if I recycle the app then this works. Is this how it works? <rule name="RedirectToanothercity" patternSyntax="ECMAScript" stopProcessing="true"> <match url="^home/cities.aspx?$" /> <conditions> <add input="{QUERY_STRING}" pattern="city=jerseycity" /> </conditions> <action type="Redirect" url="jerseycity" appendQueryString="false" />

  Read the article

• regular expression and escaping

  - by pstanton

  Sorry if this has been asked, my search brought up many off topic posts. I'm trying to convert wildcards from a user defined search string (wildcard is "*") to postgresql like wildcard "%". I'd like to handle escaping so that "%" => "\%" and "\*" => "*" I know i could replace \* with something else prior to replacing * and then swap it back, but i'd prefer not to and instead only convert * using a pattern that selects it when not proceeded by \. String convertWildcard(String like) { like = like.replaceAll("%", "\\%"); like = like.replaceAll("\\*", "%"); return like; } Assert.assertEquals("%", convertWildcard("*")); Assert.assertEquals("\%", convertWildcard("%")); Assert.assertEquals("*", convertWildcard("\*")); // FAIL Assert.assertEquals("a%b", convertWildcard("a*b")); Assert.assertEquals("a\%b", convertWildcard("a%b")); Assert.assertEquals("a*b", convertWildcard("a\*b")); // FAIL ideas welcome.

  Read the article

• Singelton on iPhone Simulator vs Singelton on real Device

  - by Helge Becker

  I am using a Singelton for some shared stuff. In the simulator, the app crashes ocasionally. Tracking the crash down shows that the the properties of my Singelton became dealocated. Those crashes never happend on a real device. Does the iPHone simulator handle memory managemend different? GC maybe? Changed the singelton to match this pattern. The iPhone Simulator dont crash now, but I am not sure about the memory handling on the real device. I assume that this solution will cause problems. What do you think?

  Read the article

• Are today's young programmers getting wrapped around the axle with patterns and practices?

  - by Robert Harvey

  Recently I have noticed a number of questions on SO that look something like this: I am writing a small program to keep a list of the songs that I keep on my ipod. I'm thinking about writing it as a 3-tier MVC Ruby on Rails web application with TDD, DDD and IOC, using a factory pattern to create the classes and a singleton to store my application settings. Do you think I'm taking the right approach? Do you think that we're handing novice programmers a very sharp knife and telling them, "Don't cut yourself with this"? NOTE: Despite the humorous tone, this is a serious (and programming-related) question.

  Read the article

• sed replacement does not work

  - by Robin Hood

  Hello, I have trouble using sed. I need to replace some lines in very deprecated HTML sites which consist of many files. My script does not work and I do not why. When I tried to find exact pattern with Netbeas it worked. find . -type f -name "*.htm?" -exec sed -i -r 's/ing\. Šuhajda Dušan\, Mírová 767\, 518 01 Dobruška\, \+420 737 980 333\,/REPLACEMENT/g' {} \; Where is the mistake? Is there an alternative to replace text without searching regular expression but plain text? Thanks for any respond.

  Read the article

• preg_replace hell

  - by Jason

  I'm trying to use preg_replace to get some data from a remote page, but I'm having a bit of an issue when it comes to sorting out the pattern. function getData($Url){ $str = file_get_contents($Url); if(strlen($str)>0){ preg_match("/\<span class=\"SectionHeader\"\>title\</span>/<br/>/\<div class=\"header2\"\>(.*)\</div\></span\>/",$str,$title); return $title[1]; } } Here's the HTML as is before I ended up throwing a million slashes at it (looks like I forgot a part or two): <span class="cell CellFullWidth"><span class="SectionHeader">mytitle</span><br/><div class="Center">Event Name</div></span> Where Event Name is the data I want to return in my function. Thanks a lot guys, this is a pain in the ass.

  Read the article

• Avoiding Nested Blocks

  - by Helium3

  If there is a view controller that wants to execute a number of block based tasks one at a time, how can the control be given back to the view controller after a completion block has executed. Lets say ViewControllerOne wants to execute a number of tasks, each relying on the result of the previous one, how would this control be given back to the viewcontroller after each completion block has been executed? I started thinking about this and I was heading towards a deeply nested block pattern that will surely only cause confusion to whoever else reads or tests it. A task executes and the completion block returns the result or error which is needed by the next task, which has its own completion task, that the next task relies on and so forth. How can the control be managed in one place, the viewcontroller? Would the completion block just call the next function that handles the next task, using a pointer to the view controller?

  Read the article

• Why should I use MVVM when it breaks built in functionality

  - by Jakob

  I'm struggling to grasp why MVVM is really a good pattern to implement in riaserivces, To me there's nothing but trouble to it, it just add's another tier that I have to code. I Get that I could change the UI, but really I don't need to. Instead i won't be able to user out of the box functionality with riaservices, datagrid, dataform all controls require some implementation. Why can't it just be simple? Is there really no way to get MVVM to automatically set "IsBusy" and all the dataform edit functionality. It's like reinventing the wheel to me, and it seems that I'd be able to write code much faster just using riaservices

  Read the article

• Dependency Injection -Colloquial explanation

  - by nettguy

  Recently I was asked to express the DI in colloquial explanation. I answered : 1) I am going to a hotel.I ordered food.The hotel management asks me to clean the plates and clean the tables.So here i am a client,I am responsible for managing the service (Instantiating,executing,disposing).But DI decouples such tasks so the service consumer no need not worry about controlling the life cycle of the service. 2) He also asked is there any microsoft API follows DI ?.I answered (This was my guess) In WCF you can create a Proxy using ChannelFactory that controls the life time of your factory. for item (1) he said only 10% is correct for item(2) he said that is factory pattern not dependency injection. Actually what went wrong in my explanation (apart from my bad English) ? What is the real answers for those? I am waiting for your valuable suggestions.

  Read the article

< Previous Page | 180 181 182 183 184 185 186 187 188 189 190 191  | Next Page >