Search Results

Search found 45920 results on 1837 pages for 'java design patterns'.

Page 649/1837 | < Previous Page | 645 646 647 648 649 650 651 652 653 654 655 656  | Next Page >

• How does a WCF server inform a WCF client about changes? (Better solution then simple polling, e.g.

  - by Ian Ringrose

  see also "WCF push to client through firewall" I need to have a WCF client that connect to a WCF server, then when some of the data changes on the server the clients need to update its display. As there is likely to be a firewall between the clients and the server. All communications must be over HTTP The server can not make an (physical) outgoing call to the client. As I am writing both the client and the server I do not need to limit the solution to only using soap etc. I am looking for built in surport for "long polling" / "Comet" etc Thanks for the most informative answer from Drew Marsh on how to implement long polling in WCF. However I thought the main “selling point” of WCF was that you could do this sort of thing just by configuring the channels to be used in the config file. E.g I want a channel that logically two way but physically incoming only.

  Read the article

• how to design a calendar control

  - by dhh

  I need to design a calendar control which should be added to our companie's application (I know there's already quite a lot calendar controls but I shall develop our own one...). How should I start, should I use a kind of table to display the days or should I completely draw my own grid? How can I do this (I do not need rdy-to-use code, I just need some ideas...)

  Read the article

• Row level user permissions, help with design

  - by bambam

  Hi, Say I am creating a forums application, I understand how to design a forum level permission system with Groups. i.e. you create a forum to group mapping, and assign users to a group to give them access to a particular forum. How can I refine the permissions to allow for row level permissions (or in forum terms, post level).

  Read the article

• How to do dependency injection python-way?

  - by Konstantin

  I've been reading a lot about python-way lately so my question is How to do dependency injection python-way? I am talking about usual scenarios when, for example, service A needs access to UserService for authorization checks.

  Read the article

• Joomla Template Design

  - by John

  Hi, Can I create any design I want and then use it in a Joomla template or is there certain rules you have to stick to? I ask this as most of the Joomla templates I see pretty much have the same layout e.g. top bar content box, right hand menu and bottom bar. Thanks

  Read the article

• eclipseFP2 haskell unix haveing issues connectiong to Scion Server

  - by Chris

  I am having troubles with using FP2 for eclipse and getting it to connect with the server. Eclipse seems to auto-detect scion_server, but I a error in the log file !ENTRY net.sf.eclipsefp.haskell.scion.client 4 4 2010-04-15 10:40:06.580 !MESSAGE The connection with the Scion server could not be established. !STACK 0 The connection with the Scion server could not be established. at net.sf.eclipsefp.haskell.scion.internal.client.ScionServer.connectToServer(ScionServer.java:328) at net.sf.eclipsefp.haskell.scion.internal.client.ScionServer.startServer(ScionServer.java:73) at net.sf.eclipsefp.haskell.scion.client.ScionInstance.start(ScionInstance.java:94) at net.sf.eclipsefp.haskell.scion.client.ScionInstance.runCommandSync(ScionInstance.java:207) at net.sf.eclipsefp.haskell.scion.internal.commands.ScionCommand.run(ScionCommand.java:136) at org.eclipse.core.internal.jobs.Worker.run(Worker.java:55) Caused by: java.net.ConnectException: Connection refused at java.net.PlainSocketImpl.socketConnect(Native Method) at java.net.PlainSocketImpl.doConnect(Unknown Source) at java.net.PlainSocketImpl.connectToAddress(Unknown Source) at java.net.PlainSocketImpl.connect(Unknown Source) at java.net.SocksSocketImpl.connect(Unknown Source) at java.net.Socket.connect(Unknown Source) at java.net.Socket.connect(Unknown Source) at java.net.Socket.<init>(Unknown Source) at java.net.Socket.<init>(Unknown Source) at net.sf.eclipsefp.haskell.scion.internal.client.ScionServer.connectToServer(ScionServer.java:345) at net.sf.eclipsefp.haskell.scion.internal.client.ScionServer.connectToServer(ScionServer.java:324)

  Read the article

• Displaying an NSString on a Custom View

  - by ilovetacos

  I have an interface that has an NSTextField, NSButton, and an NSView. When I type something in the textfield and press the button, I want the text to be drawn in the NSView. So far I have everything connected and working, except for the view. How can I connect the text and the view so that every time I press the button, the text is drawn to the view?

  Read the article

• Using DTOs and BOs

  - by ryanzec

  One area of question for me about DTOs/BOs is about when to pass/return the DTOs and when to pass/return the BOs. My gut reaction tells me to always map NHibernate to the DTOs, not BOs, and always pass/return the DTOs. Then whenever I needed to perform business logic, I would convert my DTO into a BO. The way I would do this is that my BO would have a have a constructor that takes a parameter that is the type of my interface (that defines the required fields/properties) that both my DTO and BO implement as the only argument. Then I would be able to create my BO by passing it the DTO in the constructor (since both with implement the same interface, they both with have the same properties) and then be able to perform my business logic with that BO. I would then also have a way to convert a BO to a DTO. However, I have also seen where people seem to only work with BOs and only work with DTOs in the background where to the user, it looks like there are no DTOs. What benefits/downfalls are there with this architecture vs always using BO's? Should I always being passing/returning either DTOs or BOs or mix and match (seems like mixing and matching could get confusing)?

  Read the article

• Messaging pattern question

  - by Al Bundy

  Process A is calculating values for objects a1, a2, a3 etc. and is sending results to the middleware queue (RabbitMQ). Consumers read the queue and process these results further. Periodically process A has to send a snapshot of these values, so consumers could do some other calculations. Values for these objects might change independently. The queue might look like this a1, a1, a2, a1, a2, a2, a3... Consumers process each item in the queue. The snapshot has to contain all objects and consumers will process this message for all objects in one go. So the requirement is to have a queue like this: a1, a1, a3, a2, a2, [snapshot, a1, a2, a3], a3, a1 ... The problem is that these items are of different types: one type for objects like a1, a2 and other for a snapshot. This means that they should be processed in a diferent queues, but in that case there is a race condition: consumers might process objects before processing a snapshot. Is there any pattern to solve this (quite common) problem? We are using RabbitMQ for message queueing.

  Read the article

• ASP.NET MVC Paging for a search form

  - by James Alexander

  I've read several different posts on paging w/ in MVC but none describe a scenario where I have something like a search form and then want to display the results of the search criteria (with paging) beneath the form once the user clicks submit. My problem is that, the paging solution I'm using will create <a href="..."> links that will pass the desired page like so: http://mysite.com/search/2/ and while that's all fine and dandy, I don't have the results of the query being sent to the db in memory or anything so I need to query the DB again. If the results are handled by the POST controller action for /Search and the first page of the data is rendered as such, how do I get the same results (based on the form criteria specified by the user) when the user clicks to move to page 2? Some javascript voodoo? Leverage Session State? Make my GET controller action have the same variables expected by the search criteria (but optional), when the GET action is called, instantiate a FormCollection instance, populate it and pass it to the POST action method (there-by satisfying DRY)? Can someone point me in the right direction for this scenario or provide examples that have been implemented in the past? Thanks!

  Read the article

• Can the Singleton be replaced by Factory?

  - by lostiniceland

  Hello Everyone There are already quite some posts about the Singleton-Pattern around, but I would like to start another one on this topic since I would like to know if the Factory-Pattern would be the right approach to remove this "anti-pattern". In the past I used the singleton quite a lot, also did my fellow collegues since it is so easy to use. For example, the Eclipse IDE or better its workbench-model makes heavy usage of singletons as well. It was due to some posts about E4 (the next big Eclipse version) that made me start to rethink the singleton. The bottom line was that due to this singletons the dependecies in Eclipse 3.x are tightly coupled. Lets assume I want to get rid of all singletons completely and instead use factories. My thoughts were as follows: hide complexity less coupling I have control over how many instances are created (just store the reference I a private field of the factory) mock the factory for testing (with Dependency Injection) when it is behind an interface In some cases the factories can make more than one singleton obsolete (depending on business logic/component composition) Does this make sense? If not, please give good reasons for why you think so. An alternative solution is also appreciated. Thanks Marc

  Read the article

• What is the best approach to binding commands in a ViewModel to elements in the View?

  - by Micah

  Anyone who has tried to implement RoutedCommands in WPF using M-V-VM has undoubtedly run into issues. Commands (non-UI commands that is) should be implemented in the ViewModel. For instance if I needed to save a CustomerViewModel then I would implement that as a command directly on my CustomerViewModel. However if I wanted to pop up a window to show the users addresses I would implement a ShowCustomerAddress command directly in the view since this a UI specific function. How do I define the command bindings in the viewmodel, and use them in the view?

  Read the article

• Why would it be a bad idea to have database connection open between client requests?

  - by AspOnMyNet

  1) Book I’m reading argues that connections shouldn’t be opened between client requests, since they are a finite resource. I realize that max pool size can quickly be reached and thus any further attempts to open a connection will be queued until connection becomes available and for that reason it would be imperative that we release connection as soon as possible. But assuming all request will open connection to the same DB, then I’m not sure how having a connection open between two client requests would be any less efficient than having each request first acquiring a connection from connection pool and later returning that object to connection pool? 2) Book also recommends that when database code is encapsulated in a dedicated data access class, then method M opening a database connection should also close that connection. a) I assume one reason why M should also close it, is because if method M opening the connection doesn’t also close it, but instead this connection object is used inside several methods, then it’s more likely that a programmer will forget to close it. b) Are there any other reasons why a method opening the connection should also close it? thanx

  Read the article

• Sharing a connection string

  - by coure06

  hi, I am developing a class library (C#) that i will use it for my different projects (later). My class library dll will use the connection string /data context of the project which will reference my new dll. How can i do it? Lets say i have a class Library Project named "CLP", and a website project "WP". I can add reference to CLP.dll file but how i will pass a connection string/data context object to that dll? as CLP.dll will access db based on the connection string of the "WP". Not sure my problem is clear or not!

  Read the article

• Bi-directional view model syncing with "live" collections and properties (MVVM)

  - by Schneider

  I am getting my knickers in a twist recently about View Models (VM). Just like this guy I have come to the conclusion that the collections I need to expose on my VM typically contain a different type to the collections exposed on my business objects. Hence there must be a bi-directional mapping or transformation between these two types. (Just to complicate things, on my project this data is "Live" such that as soon as you change a property it gets transmitted to other computers) I can just about cope with that concept, using a framework like Truss, although I suspect there will be a nasty surprise somewhere within. Not only must objects be transformed but a synchronization between these two collections is required. (Just to complicate things I can think of cases where the VM collection might be a subset or union of business object collections, not simply a 1:1 synchronization). I can see how to do a one-way "live" sync, using a replicating ObservableCollection or something like CLINQ. The problem then becomes: What is the best way to create/delete items? Bi-directinal sync does not seem to be on the cards - I have found no such examples, and the only class that supports anything remotely like that is the ListCollectionView. Would bi-directional sync even be a sensible way to add back into the business object collection? All the samples I have seen never seem to tackle anything this "complex". So my question is: How do you solve this? Is there some technique to update the model collections from the VM? What is the best general approach to this?

  Read the article

• Blackberry User Interface Design - Customizable UI?

  - by John Stewart

  I am trying to design a Blackberry Application and I am wondering if there are any resources on how to create custom user interface elements, skin existing ones and what other possibilities are there? I have developed a few iPhone applications with custom UI and stuff, so not sure what BB world offers in terms of UI development. Any tips, suggestions or ideas would be great.

  Read the article

• When to use Factory method pattern?

  - by Jaswant Agarwal

  When to use Factory method pattern? Please provide me some specific idea when to use it in project? and how it is a better way over new keyword?

  Read the article

• Is there any reason for an object pool to not be treated as a singleton?

  - by Chris Charabaruk

  I don't necessarily mean implemented using the singleton pattern, but rather, only having and using one instance of a pool. I don't like the idea of having just one pool (or one per pooled type). However, I can't really come up with any concrete situations where there's an advantage to multiple pools for mutable types, at least not any where a single pool can function just as well. What advantages are there to having multiple pools over a singleton pool?

  Read the article

• Disposing underlying object from finalizer in an immutable object

  - by Juan Luis Soldi

  I'm trying to wrap around Awesomium and make it look to the rest of my code as close as possible to NET's WebBrowser since this is for an existing application that already uses the WebBrowser. In this library, there is a class called JSObject which represents a javascript object. You can get one of this, for instance, by calling the ExecuteJavascriptWithResult method of the WebView class. If you'd call it like myWebView.ExecuteJavascriptWithResult("document", string.Empty).ToObject(), then you'd get a JSObject that represents the document. I'm writing an immutable class (it's only field is a readonly JSObject object) called JSObjectWrap that wraps around JSObject which I want to use as base class for other classes that would emulate .NET classes such as HtmlElement and HtmlDocument. Now, these classes don't implement Dispose, but JSObject does. What I first thought was to call the underlying JSObject's Dispose method in my JSObjectWrap's finalizer (instead of having JSObjectWrap implement Dispose) so that the rest of my code can stay the way it is (instead of having to add using's everywhere and make sure every JSObjectWrap is being properly disposed). But I just realized if more than two JSObjectWrap's have the same underlying JSObject and one of them gets finalized this will mess up the other JSObjectWrap. So now I'm thinking maybe I should keep a static Dictionary of JSObjects and keep count of how many of each of them are being referenced by a JSObjectWrap but this sounds messy and I think could cause major performance issues. Since this sounds to me like a common pattern I wonder if anyone else has a better idea.

  Read the article

• What is the basic pattern for using (N)Hibernate?

  - by Vilx-

  I'm creating a simple Windows Forms application with NHibernate and I'm a bit confused about how I'm supposed to use it. To quote the manual: ISession (NHibernate.ISession) A single-threaded, short-lived object representing a conversation between the application and the persistent store. Wraps an ADO.NET connection. Factory for ITransaction. Holds a mandatory (first-level) cache of persistent objects, used when navigating the object graph or looking up objects by identifier. Now, suppose I have the following scenario: I have a simple classifier which is a MSSQL table with two columns - ID (auto_increment) and Name (nvarchar). To edit this classifier I create a form which contains a single gridview and two buttons - OK and Cancel. The user can nearly directly edit the table in the gridview, and when he hits OK the changes he made are persisted to the DB (or if he hits cancel, nothing happens). Now, I have several questions about how to organize this: What should the lifetime of my ISession be? Should I create a single ISession for my whole application; an ISession for each of my forms (the application is single-threaded MDI); or an ISession for every DB operation/transaction? Does NHibernate offer some kind of built-in dirty tracking or must I do this myself? The manual mentions something like it here and there but does not go into details. How is this done? Is there not a huge overhead? Is it somehow tied with the cache(s) that NHibernate has? What are these caches for? Are they not specific to a single ISession? That is, if I use a seperate ISession for every transaction, won't it break the dirty tracking? How does the built-in dirty tracking detect deleted objects?

  Read the article

• doubleton pattern in C++

  - by benjamin button

  I am aware of the singleton pattern in C++. but what is the logic to get two instances of the object? is there any such pattern where we could easily get 2 pattern. for the logic i could think of is that i can change the singleton pattern itself to have two objects created inside the class.this works. but if the requirement grows like if i need only 3 or only 4 what is the deswign pattern that i could think of to qualify such requirement?

  Read the article

• What are the responsibilities of the data layer?

  - by alimac83

  I'm working on a project where I had to add a data layer to my application. I've always thought that the data layer is purely responsible for CRUD functions ie. shouldn't really contain any logic but should simply retrieve data for the business layer to manipulate. However I'm a little confused with my project because I'm not sure whether I've structured my app correctly for this scenario. Basically I'm trying to retrieve a list of products from the database that fall within a certain pricing threshold. At the moment I have a function in my data layer that basically returns all products where price min threshold and price < max threshold. But it got me thinking that maybe this is incorrect. Should the data layer simply return a list of ALL products and then the business logic do the filtering? I'm pretty confused over whether the data layer should simply provide methods that allow the business layer to get raw data or whether it should be responsible for getting filtered data too? If anyone has an article or something explaining this in detail it'd be very helpful. Thanks

  Read the article

• Implement Exception Handling in ASP.NET C# Project

  - by Shrewd Demon

  hi, I have an application that has many tiers. as in, i have... Presentation Layer (PL) - contains all the html My Codes Layer (CL) - has all my code Entity Layer (EL) - has all the container entities Business Logic Layer (BLL) - has the necessary business logic Data Logic Layer (DLL) - any logic against data Data Access Layer (DAL) - one that accesses data from the database Now i want to provide error handling in my DLL since it is responsible for executing statement like ExecureScalar and all.... And i am confused as to how to go about it...i mean do i catch the error in the DLL and throw it back to the BLL and from there throw it back to my code or what.... can any one please help me how do i implement a clean and easy error handling techinque help you be really appreciated. Thank you.

  Read the article

• android numberformat exception

  - by asifkt

  my application shows this number format exception errror while running. 1 0-22 11:09:06.095: WARN/System.err(290): at java.lang.Long.parseLong(Long.java:330) 10-22 11:09:06.095: WARN/System.err(290): at java.lang.Long.parseLong(Long.java:307) 10-22 11:09:06.105: WARN/System.err(290): at com.htc.socialnetwork.facebook.FacebookUtils.getSyncInterval(FacebookUtils.java:54) 10-22 11:09:06.105: WARN/System.err(290): at com.htc.socialnetwork.facebook.remote.FacebookReceiver.getSyncInterval(FacebookReceiver.java:269) 10-22 11:09:06.105: WARN/System.err(290): at com.htc.socialnetwork.facebook.remote.FacebookReceiver.onReceive(FacebookReceiver.java:196) 10-22 11:09:06.105: WARN/System.err(290): at android.app.ActivityThread.handleReceiver(ActivityThread.java:2751) 10-22 11:09:06.105: WARN/System.err(290): at android.app.ActivityThread.access$3100(ActivityThread.java:126) 10-22 11:09:06.105: WARN/System.err(290): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1982) 10-22 11:09:06.105: WARN/System.err(290): at android.os.Handler.dispatchMessage(Handler.java:99) 10-22 11:09:06.105: WARN/System.err(290): at android.os.Looper.loop(Looper.java:123) 10-22 11:09:06.105: WARN/System.err(290): at android.app.ActivityThread.main(ActivityThread.java:4603) 10-22 11:09:06.105: WARN/System.err(290): at java.lang.reflect.Method.invokeNative(Native Method) 10-22 11:09:06.105: WARN/System.err(290): at java.lang.reflect.Method.invoke(Method.java:521) 10-22 11:09:06.105: WARN/System.err(290): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860) 10-22 11:09:06.105: WARN/System.err(290): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618) 10-22 11:09:06.115: WARN/System.err(290): at dalvik.system.NativeStart.main(Native Method) anybody please help me to get the reason for this error

  Read the article

• Optional Member Objects

  - by David Relihan

  Okay, so you have a load of methods sprinkled around your systems main class. So you do the right thing and refactor by creating a new class and perform move method(s) into a new class. The new class has a single responsibility and all is right with the world again: class Feature { public: Feature(){}; void doSomething(); void doSomething1(); void doSomething2(); }; So now your original class has a member variable of type object: Feature _feature; Which you will call in the main class. Now if you do this many times, you will have many member-objects in your main class. Now these features may or not be required based on configuration so in a way it's costly having all these objects that may or not be needed. Can anyone suggest a way of improving this? At the moment I plan to test in the newly created class if the feature is enabled - so the when a call is made to method I will return if it is not enabled. I could have a pointer to the object and then only call new if feature is enabled - but this means I will have to test before I call a method on it which would be potentially dangerous and not very readable. Would having an auto_ptr to the object improve things: auto_ptr<Feature> feature; Or am I still paying the cost of object invokation even though the object may\or may not be required. BTW - I don't think this is premeature optimisation - I just want to consider the possibilites.

  Read the article

< Previous Page | 645 646 647 648 649 650 651 652 653 654 655 656  | Next Page >