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• What to choose API based server or Socket based server for data driven application

  - by Imdad

  I am working on a project which has a Desktop Application for MAC/COCOA, a native application for iPhone another native application in iPad. All the application do almost same thing. The applications are data driven applications. Every communication to server is made via a restful API developed in PHP. When a user logs in a lot of data is fetched from server. And to remain in sync with server pooling is done. As there are lot of data to pool it makes application slower and un-reliable. A possible solution that comes into my mind is to use Socket based server. My question is that will it reasonably improve the performance? And which technology (of sockets) will be good as a server side solution for data driven application? I have heard a lot about Node.js. Please give your suggestions.

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• singleton factory connection pdo

  - by Scarface

  Hey guys I am having a lot of trouble trying to understand this and I was just wondering if someone could help me with some questions. I found some code that is supposed to create a connection with pdo. The problem I was having was having my connection defined within functions. Someone suggested globals but then pointed to a 'better' solution http://stackoverflow.com/questions/130878/global-or-singleton-for-database-connection. My questions with this code are. PS I cannot format this code on this page so see the link if you cannot read What is the point of the connection factory? What goes inside new ConnectionFactory(...) When the connection is defined $db = new PDO(...); why is there no try or catch (I use those for error handling)? Does this then mean I have to use try and catch for every subsequent query? class ConnectionFactory { private static $factory; public static function getFactory() { if (!self::$factory) self::$factory = new ConnectionFactory(...); return self::$factory; } private $db; public function getConnection() { if (!$db) $db = new PDO(...); return $db; } } function getSomething() { $conn = ConnectionFactory::getFactory()-getConnection(); . . . }

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• javascript plugin - singleton pattern?

  - by Adam Kiss

  intro Hello, I'm trying to develop some plugin or/*and* object in javascript, which will control some properties over some object. It will also use jQuery, to ease development. idea This is in pseudocode to give you an idea, since I can't really describe it in english with the right words, it's impossible to go and use google to find out what I want to use (and learn). I will have plugin (maybe object?) with some variables and methods: plugin hideshow(startupconfig){ var c, //collection add: function(what){ c += what; }, do: function(){ c.show().hide().stop(); //example code } } and I will use it this way (or sort-of): var p = new Plugin(); p .add($('p#simple')) .add($('p#simple2')) .do(); note I'm not really looking for jQuery plugin tutorials - it's more like usage of singleton pattern in document in javascript, jQuery is mentione only because it will be used to modify dom and simplify selectors, jQuery plugin maybe just for that one little function add. I'm looking for something, that will sit on top of my document and call functions from itselft based on timer, or user actions, or whatever. problems I don't really know where to start with construction of this object/plugin I'm not really sure how to maintain one variable, which is collection of jQuery objects (something like $('#simple, #simple2');) I would maybe like to extedn jQuery with $.fn.addToPlugin to use chaining of objects, but that should be simple (really just each( p.add($(this)); )) I hope I make any sense, ideas, links or advices appreciated.

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• java singleton instantiation

  - by jurchiks

  I've found three ways of instantiating a Singleton, but I have doubts as to whether any of them is the best there is. I'm using them in a multi-threaded environment and prefer lazy instantiation. Sample 1: private static final ClassName INSTANCE = new ClassName(); public static ClassName getInstance() { return INSTANCE; } Sample 2: private static class SingletonHolder { public static final ClassName INSTANCE = new ClassName(); } public static ClassName getInstance() { return SingletonHolder.INSTANCE; } Sample 3: private static ClassName INSTANCE; public static synchronized ClassName getInstance() { if (INSTANCE == null) INSTANCE = new ClassName(); return INSTANCE; } The project I'm using ATM uses Sample 2 everywhere, but I kind of like Sample 3 more. There is also the Enum version, but I just don't get it. The question here is - in which cases I should/shouldn't use any of these variations? I'm not looking for lengthy explanations though (there's plenty of other topics about that, but they all eventually turn into arguing IMO), I'd like it to be understandable with few words.

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• Dependency Injection into your Singleton

  - by Langali

  I have a singleton that has a spring injected Dao (simplified below): public class MyService<T> implements Service<T> { private final Map<String, T> objects; private static MyService instance; MyDao myDao; public void set MyDao(MyDao myDao) { this. myDao = myDao; } private MyService() { this.objects = Collections.synchronizedMap(new HashMap<String, T>()); // start a background thread that runs for ever } public static synchronized MyService getInstance() { if(instance == null) { instance = new MyService(); } return instance; } public void doSomething() { myDao.persist(objects); } } My spring config will probably look like this: <bean id="service" class="MyService" factory-method="getInstance"/> But this will instantiate the MyService during startup. Is there a programmatic way to do a dependency injection of MyDao into MyService, but not have spring manage the MyService? Basically I want to be able to do this from my code: MyService.getInstance().doSomething(); while having spring inject the MyDao for me.

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• PHP OOP singleton doesn't return object

  - by Misiur

  Weird trouble. I've used singleton multiple times but this particular case just doesn't want to work. Dump says that instance is null. define('ROOT', "/"); define('INC', 'includes/'); define('CLS', 'classes/'); require_once(CLS.'Core/Core.class.php'); $core = Core::getInstance(); var_dump($core->instance); $core->settings(INC.'config.php'); $core->go(); Core class class Core { static $instance; public $db; public $created = false; private function __construct() { $this->created = true; } static function getInstance() { if(!self::$instance) { self::$instance = new Core(); } else { return self::$instance; } } public function settings($path = null) { ... } public function go() { ... } } Error code Fatal error: Call to a member function settings() on a non-object in path It's possibly some stupid typo, but I don't have any errors in my editor. Thanks for the fast responses as always.

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• Using block around a static/singleton resource reference

  - by byte

  This is interesting (to me anyway), and I'd like to see if anyone has a good answer and explanation for this behavior. Say you have a singleton database object (or static database object), and you have it stored in a class Foo. public class Foo { public static SqlConnection DBConn = new SqlConnection(ConfigurationManager.ConnectionStrings["BAR"].ConnectionString); } Then, lets say that you are cognizant of the usefulness of calling and disposing your connection (pretend for this example that its a one-time use for purposes of illustration). So you decide to use a 'using' block to take care of the Dispose() call. using (SqlConnection conn = Foo.DBConn) { conn.Open(); using (SqlCommand cmd = new SqlCommand()) { cmd.Connection = conn; cmd.CommandType = System.Data.CommandType.StoredProcedure; cmd.CommandText = "SP_YOUR_PROC"; cmd.ExecuteNonQuery(); } conn.Close(); } This fails, with an error stating that the "ConnectionString property is not initialized". It's not an issue with pulling the connection string from the app.config/web.config. When you investigate in a debug session you see that Foo.DBConn is not null, but contains empty properties. Why is this?

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• efficient thread-safe singleton in C++

  - by user168715

  The usual pattern for a singleton class is something like static Foo &getInst() { static Foo *inst = NULL; if(inst == NULL) inst = new Foo(...); return *inst; } However, it's my understanding that this solution is not thread-safe, since 1) Foo's constructor might be called more than once (which may or may not matter) and 2) inst may not be fully constructed before it is returned to a different thread. One solution is to wrap a mutex around the whole method, but then I'm paying for synchronization overhead long after I actually need it. An alternative is something like static Foo &getInst() { static Foo *inst = NULL; if(inst == NULL) { pthread_mutex_lock(&mutex); if(inst == NULL) inst = new Foo(...); pthread_mutex_unlock(&mutex); } return *inst; } Is this the right way to do it, or are there any pitfalls I should be aware of? For instance, are there any static initialization order problems that might occur, i.e. is inst always guaranteed to be NULL the first time getInst is called?

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• Using a Data Management Singleton

  - by Dan Ray

  Here's my singleton code (pretty much boilerplate): @interface DataManager : NSObject { NSMutableArray *eventList; } @property (nonatomic, retain) NSMutableArray *eventList; +(DataManager*)sharedDataManager; @end And then the .m: #import "DataManager.h" static DataManager *singletonDataManager = nil; @implementation DataManager @synthesize eventList; +(DataManager*)sharedDataManager { @synchronized(self) { if (!singletonDataManager) { singletonDataManager = [[DataManager alloc] init]; } } NSLog(@"Pulling a copy of shared manager."); return singletonDataManager; } So then in my AppDelegate, I load some stuff before launching my first view: NSMutableArray *eventList = [DataManager sharedDataManager].eventList; .... NSLog(@"Adding event %@ to eventList", event.title); [eventList addObject:event]; NSLog(@"eventList now has %d members", [eventList count]); [event release]; As you can see, I've peppered the code with NSLog love notes to myself. The output to the Log reads like: 2010-05-10 09:08:53.355 MyApp[2037:207] Adding event Woofstock Music Festival to eventList 2010-05-10 09:08:53.355 MyApp[2037:207] eventList now has 0 members 2010-05-10 09:08:53.411 MyApp[2037:207] Adding event Test Event for Staging to eventList 2010-05-10 09:08:53.411 MyApp[2037:207] eventList now has 0 members 2010-05-10 09:08:53.467 MyApp[2037:207] Adding event Montgomery Event to eventList 2010-05-10 09:08:53.467 MyApp[2037:207] eventList now has 0 members 2010-05-10 09:08:53.524 MyApp[2037:207] Adding event Alamance County Event For June to eventList 2010-05-10 09:08:53.524 MyApp[2037:207] eventList now has 0 members ... What gives? I have no errors getting to my eventList NSMutableArray. But I addObject: fails silently?

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• Create table class as a singleton

  - by Mark

  I got a class that I use as a table. This class got an array of 16 row classes. These row classes all have 6 double variables. The values of these rows are set once and never change. Would it be a good practice to make this table a singleton? The advantage is that it cost less memory, but the table will be called from multiple threads so I have to synchronize my code which way cause a bit slower application. However lookups in this table are probably a very small portion of the total code that is executed. EDIT: This is my code, are there better ways to do this or is this a good practice? Removed synchronized keyword according to recommendations in this question. final class HalfTimeTable { private HalfTimeRow[] table = new HalfTimeRow[16]; private static final HalfTimeTable instance = new HalfTimeTable(); private HalfTimeTable() { if (instance != null) { throw new IllegalStateException("Already instantiated"); } table[0] = new HalfTimeRow(4.0, 1.2599, 0.5050, 1.5, 1.7435, 0.1911); table[1] = new HalfTimeRow(8.0, 1.0000, 0.6514, 3.0, 1.3838, 0.4295); //etc } @Override @Deprecated public Object clone() throws CloneNotSupportedException { throw new CloneNotSupportedException(); } public static HalfTimeTable getInstance() { return instance; } public HalfTimeRow getRow(int rownumber) { return table[rownumber]; } }

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• VB.NET looping through XML to store in singleton

  - by rockinthesixstring

  I'm having a problem with looping through an XML file and storing the value in a singleton My XML looks like this <values> <value></value> <value>$1</value> <value>$5,000</value> <value>$10,000</value> <value>$15,000</value> <value>$25,000</value> <value>$50,000</value> <value>$75,000</value> <value>$100,000</value> <value>$250,000</value> <value>$500,000</value> <value>$750,000</value> <value>$1,000,000</value> <value>$1,250,000</value> <value>$1,500,000</value> <value>$1,750,000</value> <value>$2,000,000</value> <value>$2,500,000</value> <value>$3,000,000</value> <value>$4,000,000</value> <value>$5,000,000</value> <value>$7,500,000</value> <value>$10,000,000</value> <value>$15,000,000</value> <value>$25,000,000</value> <value>$50,000,000</value> <value>$100,000,000</value> <value>$100,000,000+</value> </values> And my function looks like this Public Class LoadValues Private Shared SearchValuesInstance As List(Of SearchValues) = Nothing Public Shared ReadOnly Property LoadSearchValues As List(Of SearchValues) Get Dim sv As New List(Of SearchValues) If SearchValuesInstance Is Nothing Then Dim objDoc As XmlDocument = New XmlDataDocument Dim objRdr As XmlTextReader = New XmlTextReader(HttpContext.Current.Server.MapPath("~/App_Data/Search-Values.xml")) objRdr.Read() objDoc.Load(objRdr) Dim root As XmlElement = objDoc.DocumentElement Dim itemNodes As XmlNodeList = root.SelectNodes("/values") For Each n As XmlNode In itemNodes sv.Add(New SearchValues(n("@value").InnerText, n("@value").InnerText)) Next SearchValuesInstance = sv Else : sv = SearchValuesInstance End If Return sv End Get End Property End Class My problem is that I'm getting an object not set to an instance of an object on the sv.Add(New SearchValues(n("@value").InnerText, n("@value").InnerText)) line.

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• Should I create protected constructor for my singleton classes?

  - by Vijay Shanker

  By design, in Singleton pattern the constructor should be marked private and provide a creational method retuning the private static member of the same type instance. I have created my singleton classes like this only. public class SingletonPattern {// singleton class private static SingletonPattern pattern = new SingletonPattern(); private SingletonPattern() { } public static SingletonPattern getInstance() { return pattern; } } Now, I have got to extend a singleton class to add new behaviors. But the private constructor is not letting be define the child class. I was thinking to change the default constructor to protected constructor for the singleton base class. What can be problems, if I define my constructors to be protected? Looking for expert views....

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• Problem with SIngleton Class

  - by zp26

  Hi, I have a prblem with my code. I have a viewController and a singleton class. When i call the method readXml and run a for my program update the UITextView. When i call the clearTextView method the program exit with EXC_BAD_ACCESS. The prblem it's the name of the variable position. This is invalid but i don't change anything between the two methods. You have an idea? My code: #import "PositionIdentifierViewController.h" #import "WriterXML.h" #import "ParserXML.h" #define timeToScan 0.1 @implementation PositionIdentifierViewController @synthesize accelerometer; @synthesize actualPosition; @synthesize actualX; @synthesize actualY; @synthesize actualZ; -(void)updateTextView:(NSString*)nomePosizione { NSString *string = [NSString stringWithFormat:@"%@",nomePosizione]; textEvent.text = [textEvent.text stringByAppendingString:@"\n"]; textEvent.text = [textEvent.text stringByAppendingString:string]; } -(IBAction)clearTextEvent{ textEvent.text = @""; //with this for my program exit for(int i=0; i<[[sharedController arrayPosition]count]; i++){ NSLog(@"sononelfor"); Position *tempPosition = [[Position alloc]init]; tempPosition = [[sharedController arrayPosition]objectAtIndex:i]; [self updateTextView:(NSString*)[tempPosition name]]; } } -(void)readXml{ if([sharedController readXml]){ UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Caricamento Posizioni" message:@"Caricamento effettuato con successo" delegate:self cancelButtonTitle:@"Cancel" otherButtonTitles:nil]; [alert show]; [alert release]; NSString *string = [NSString stringWithFormat:@"%d", [[sharedController arrayPosition]count]]; [self updateTextView:(NSString*)string]; //with only this the program is ok for(int i=0; i<[[sharedController arrayPosition]count]; i++){ NSLog(@"sononelfor"); Position *tempPosition = [[Position alloc]init]; tempPosition = [[sharedController arrayPosition]objectAtIndex:i]; [self updateTextView:(NSString*)[tempPosition name]]; } } else{ UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Caricamento Posizioni" message:@"Caricamento non riuscito" delegate:self cancelButtonTitle:@"Cancel" otherButtonTitles:nil]; [alert show]; [alert release]; } } // Implement viewDidLoad to do additional setup after loading the view, typically from a nib. - (void)viewDidLoad { [super viewDidLoad]; sharedController = [SingletonController sharedSingletonController]; actualPosition = [[Position alloc]init]; self.accelerometer = [UIAccelerometer sharedAccelerometer]; self.accelerometer.updateInterval = timeToScan; self.accelerometer.delegate = self; actualX=0; actualY=0; actualZ=0; [self readXml]; } - (void)dealloc { [super dealloc]; [actualPosition dealloc]; [super dealloc]; } @end #import "SingletonController.h" #import "Position.h" #import "WriterXML.h" #import "ParserXML.h" #define standardSensibility 2 #define timeToScan .1 @implementation SingletonController @synthesize arrayPosition; @synthesize arrayMovement; @synthesize actualPosition; @synthesize actualMove; @synthesize stopThread; +(SingletonController*)sharedSingletonController{ static SingletonController *sharedSingletonController; @synchronized(self) { if(!sharedSingletonController){ sharedSingletonController = [[SingletonController alloc]init]; } } return sharedSingletonController; } -(BOOL)readXml{ ParserXML *newParser = [[ParserXML alloc]init]; if([newParser startParsing:(NSString*)@"filePosizioni.xml"]){ [arrayPosition addObjectsFromArray:[newParser arrayPosition]]; return TRUE; } else return FALSE; } -(id)init{ self = [super init]; if (self != nil) { arrayPosition = [[NSMutableArray alloc]init]; arrayMovement = [[NSMutableArray alloc]init]; actualPosition = [[Position alloc]init]; actualMove = [[Movement alloc]init]; stopThread = FALSE; } return self; } -(void) dealloc { [super dealloc]; } @end

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• Application that will install application

  - by user23950

  I'm thinking of a software that comes with pc decrapifier. Which can do the exact opposite of what pc decrapifier can do. Install a number of applications in one click. Is there an application like that?Not a web app please, I already know of that but I forgot the name, so if you know that please comment.

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• How to customize application menu for java application in Mac OS

  - by Sunil Kumar Sahoo

  Hi I have created a java application. I found there is an application menu and about application in Mac. I donot know how to customize those about application dialog. i Want to write my own dialog instead of that dialog. How to do this. I found that I have to use Application Adapter. Thanks Sunil Kumar Sahoo

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• Choosing an application server for web application development

  - by harigm

  My manager has asked me to suggest an application server for web application development work. What are the factors that needs to be considered before we select any application server for web application development in Java J2EE development? If I select one now and IN future and I want to change to some other application server, is that minimum effort to change?

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• Chossing an application server for an web application development

  - by harigm

  My manager has asked me to suggest an application server for the web application development work, What are the factors that needs to be considered before we select any application server for web application development in Java J2ee development? If I select one now and IN future, if I want to change to some other application server, Is if that minimum effort to change?

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• Application switcher is broken

  - by Byron Hawkins

  After a normal update of my Ubuntu 12.04 install last week, my application switcher has stopped working. I've tried all different settings in CompizConfig, including a variety of shortcut keys and both switcher versions ("Application Switcher" and "Static Application Switcher"). So far there has been no way to get any form of application switcher to appear on my screen. Can anyone give me an idea what might be wrong, or where I might look for more information? Thanks for your help.

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• Curing the Database-Application mismatch

  - by Phil Factor

  If an application requires access to a database, then you have to be able to deploy it so as to be version-compatible with the database, in phase. If you can deploy both together, then the application and database must normally be deployed at the same version in which they, together, passed integration and functional testing.  When a single database supports more than one application, then the problem gets more interesting. I’ll need to be more precise here. It is actually the application-interface definition of the database that needs to be in a compatible ‘version’.  Most databases that get into production have no separate application-interface; in other words they are ‘close-coupled’.  For this vast majority, the whole database is the application-interface, and applications are free to wander through the bowels of the database scot-free.  If you’ve spurned the perceived wisdom of application architects to have a defined application-interface within the database that is based on views and stored procedures, any version-mismatch will be as sensitive as a kitten.  A team that creates an application that makes direct access to base tables in a database will have to put a lot of energy into keeping Database and Application in sync, to say nothing of having to tackle issues such as security and audit. It is not the obvious route to development nirvana. I’ve been in countless tense meetings with application developers who initially bridle instinctively at the apparent restrictions of being ‘banned’ from the base tables or routines of a database.  There is no good technical reason for needing that sort of access that I’ve ever come across.  Everything that the application wants can be delivered via a set of views and procedures, and with far less pain for all concerned: This is the application-interface.  If more than zero developers are creating a database-driven application, then the project will benefit from the loose-coupling that an application interface brings. What is important here is that the database development role is separated from the application development role, even if it is the same developer performing both roles. The idea of an application-interface with a database is as old as I can remember. The big corporate or government databases generally supported several applications, and there was little option. When a new application wanted access to an existing corporate database, the developers, and myself as technical architect, would have to meet with hatchet-faced DBAs and production staff to work out an interface. Sure, they would talk up the effort involved for budgetary reasons, but it was routine work, because it decoupled the database from its supporting applications. We’d be given our own stored procedures. One of them, I still remember, had ninety-two parameters. All database access was encapsulated in one application-module. If you have a stable defined application-interface with the database (Yes, one for each application usually) you need to keep the external definitions of the components of this interface in version control, linked with the application source,  and carefully track and negotiate any changes between database developers and application developers.  Essentially, the application development team owns the interface definition, and the onus is on the Database developers to implement it and maintain it, in conformance.  Internally, the database can then make all sorts of changes and refactoring, as long as source control is maintained.  If the application interface passes all the comprehensive integration and functional tests for the particular version they were designed for, nothing is broken. Your performance-testing can ‘hang’ on the same interface, since databases are judged on the performance of the application, not an ‘internal’ database process. The database developers have responsibility for maintaining the application-interface, but not its definition,  as they refactor the database. This is easily tested on a daily basis since the tests are normally automated. In this setting, the deployment can proceed if the more stable application-interface, rather than the continuously-changing database, passes all tests for the version of the application. Normally, if all goes well, a database with a well-designed application interface can evolve gracefully without changing the external appearance of the interface, and this is confirmed by integration tests that check the interface, and which hopefully don’t need to be altered at all often.  If the application is rapidly changing its ‘domain model’  in the light of an increased understanding of the application domain, then it can change the interface definitions and the database developers need only implement the interface rather than refactor the underlying database.  The test team will also have to redo the functional and integration tests which are, of course ‘written to’ the definition.  The Database developers will find it easier if these tests are done before their re-wiring  job to implement the new interface. If, at the other extreme, an application receives no further development work but survives unchanged, the database can continue to change and develop to keep pace with the requirements of the other applications it supports, and needs only to take care that the application interface is never broken. Testing is easy since your automated scripts to test the interface do not need to change. The database developers will, of course, maintain their own source control for the database, and will be likely to maintain versions for all major releases. However, this will not need to be shared with the applications that the database servers. On the other hand, the definition of the application interfaces should be within the application source. Changes in it have to be subject to change-control procedures, as they will require a chain of tests. Once you allow, instead of an application-interface, an intimate relationship between application and database, we are in the realms of impedance mismatch, over and above the obvious security problems.  Part of this impedance problem is a difference in development practices. Whereas the application has to be regularly built and integrated, this isn’t necessarily the case with the database.  An RDBMS is inherently multi-user and self-integrating. If the developers work together on the database, then a subsequent integration of the database on a staging server doesn’t often bring nasty surprises. A separate database-integration process is only needed if the database is deliberately built in a way that mimics the application development process, but which hampers the normal database-development techniques.  This process is like demanding a official walking with a red flag in front of a motor car.  In order to closely coordinate databases with applications, entire databases have to be ‘versioned’, so that an application version can be matched with a database version to produce a working build without errors.  There is no natural process to ‘version’ databases.  Each development project will have to define a system for maintaining the version level. A curious paradox occurs in development when there is no formal application-interface. When the strains and cracks happen, the extra meetings, bureaucracy, and activity required to maintain accurate deployments looks to IT management like work. They see activity, and it looks good. Work means progress.  Management then smile on the design choices made. In IT, good design work doesn’t necessarily look good, and vice versa.

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• Help in (re)designing my Swing application

  - by Harihar Das

  I have developed a Swing application that controls execution of several script like jobs. I need to display the interim output of the jobs concurrently. I have followed MVC while writing the application. The application is working as expected. But off late I have the following requirements in hand: A few of the script jobs need special user privileges to execute so as to access specialized resources. There seems to be now way in Java to impersonate as a different user while running an application.[examined in this question]. Also trying to run the Swing application as a scheduled task in windows is not helping. Once started the jobs should be running even if the user logs off after starting the jobs. I am thinking of separating the execution logic from the UI and run that as a service; and introduce JMS in between the two layers so as to store/retrieve the interim the output. Note: I need to run this application on windows Any ideas on meeting my requirements will be highly appreciated.

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• Application workflow

  - by manseuk

  I am in the planning process for a new application, the application will be written in PHP (using the Symfony 2 framework) but I'm not sure how relevant that is. The application will be browser based, although there will eventually be API access for other systems to interact with the data stored within the application, again probably not relavent at this point. The application manages SIM cards for lots of different providers - each SIM card belongs to a single provider but a single customer might have many SIM cards across many providers. The application allows the user to perform actions against the SIM card - for example Activate it, Barr it, Check on its status etc Some of the providers provide an API for doing this - so a single access point with multiple methods eg activateSIM, getStatus, barrSIM etc. The method names differ for each provider and some providers offer methods for extra functions that others don't. Some providers don't have APIs but do offer these methods by sending emails with attachments - the attachments are normally a CSV file that contains the SIM reference and action required - the email is processed by the provider and replied to once the action has been complete. To give you an example - the front end of my application will provide a customer with a list of SIM cards they own and give them access to the actions that are provided by the provider of each specific SIM card - some methods may require extra data which will either be stored in the backend or collected from the user frontend. Once the user has selected their action and added any required data I will handle the process in the backend and provide either instant feedback, in the case of the providers with APIs, or start the process off by sending an email and waiting for its reply before processing it and updating the backend so that next time the user checks the SIM card its status is correct (ie updated by a backend process). My reason for creating this question is because I'm stuck !! I'm confused about how to approach the actual workflow logic. I was thinking about creating a Provider Interface with the most common methods getStatus, activateSIM and barrSIM and then implementing that interface for each provider. So class Provider1 implements Provider - Then use a Factory to create the required class depending on user selected SIM card and invoking the method selected. This would work fine if all providers offered the same methods but they don't - there are a subset which are common but some providers offer extra methods - how can I implement that flexibly ? How can I deal with the processes where the workflow is different - ie some methods require and API call and value returned and some require an email to be sent and the next stage of the process doesn't start until the email reply is recieved ... Please help ! (I hope this is a readable question and that this is the correct place to be asking) Update I guess what I'm trying to avoid is a big if or switch / case statement - some design pattern that gives me a flexible approach to implementing this kind of fluid workflow .. anyone ?

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• How To Create Per-Request Singleton in Pylons?

  - by dave mankoff

  In our Pylons based web-app, we're creating a class that essentially provides some logging functionality. We need a new instance of this class for each http request that comes in, but only one per request. What is the proper way to go about this? Should we just create the object in middleware and store in in request.environ? Is there a more appropriate way to go about this?

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• Share same object instance (singleton) between processes

  - by Cory

  I can do this for a single process (single .exe) but how can I do it between processes?

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• What is design principle behind Servlets being Singleton

  - by Sandeep Jindal

  A servlet container "generally" create one instance of a servlet and different threads of the same instance to serve multiple requests. (I know this can be changed using deprecated SingleThreadModel and other features, but this is the usual way). I thought, the simple reason behind this is performance gain, as creating threads is better than creating instances. But it seems this is not the reason. On the other hand, creating instances have little advantage that developers never have to worry about thread safety. I am trying to understand the reason for this decision over the trade-off of thread-safety.

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• PHP Overloading, singleton instance

  - by jamalali81

  I've sort of created my own MVC framework and am curious as to how other frameworks can send properties from the "controller" to the "view". Zend does something along the lines of $this->view->name = 'value'; My code is: file: services_hosting.php class services_hosting extends controller { function __construct($sMvcName) { parent::__construct($sMvcName); $this->setViewSettings(); } public function setViewSettings() { $p = new property; $p->banner = '/path/to/banners/home.jpg'; } } file: controller.php class controller { public $sMvcName = "home"; function __construct($sMvcName) { if ($sMvcName) { $this->sMvcName = $sMvcName; } include('path/to/views/view.phtml'); } public function renderContent() { include('path/to/views/'.$this->sMvcName.'.phtml'); } } file: property.php class property { private $data = array(); protected static $_instance = null; public static function getInstance() { if (null === self::$_instance) { self::$_instance = new self(); } return self::$_instance; } public function __set($name, $value) { $this->data[$name] = $value; } public function __get($name) { if (array_key_exists($name, $this->data)) { return $this->data[$name]; } } public function __isset($name) { return isset($this->data[$name]); } public function __unset($name) { unset($this->data[$name]); } } In my services_hosting.phtml "view" file I have: <img src="<?php echo $this->p->banner ?>" /> This just does not work. Am I doing something fundamentally wrong or is my logic incorrect? I seem to be going round in circles at the moment. Any help would be very much appreciated.

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