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  • use Services in MVVM

    - by netmajor
    I want to use Services(WCF/RIA /Web) to take data from Entity Data Model class (maybe NHibernate class) and prepared it special for View layer binding. I have few Silverlight page, so should I create for each page separate service class ? Or create one interface and all method will implement it in one service class? Do You have some advice helped with my with services ?

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  • How are distributed services better than distributed objects?

    - by Gabriel Šcerbák
    I am not interested in the technology e.g. CORBA vs Web Services, I am interested in principles. When we are doing OOP, why should we have something so procedural at higher level? Is not it the same as with OOP and relational databases? Often services are supported through code generation, apart from boilerplate, I think it is because we new SOM - service object mapper. So again, what are the reasons for wervices rather than objects?

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  • implementation Services in MVVM

    - by netmajor
    I want to use Services(WCF/RIA /Web) to take data from Entity Data Model class (maybe NHibernate class) and prepared it special for View layer binding. I have few Silverlight page, so should I create for each page separate service class ? Or create one interface and all method will implement it in one service class? Do You have some advice helped with my with services ?

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  • Data access pattern

    - by andlju
    I need some advice on what kind of pattern(s) I should use for pushing/pulling data into my application. I'm writing a rule-engine that needs to hold quite a large amount of data in-memory in order to be efficient enough. I have some rather conflicting requirements; It is not acceptable for the engine to always have to wait for a full pre-load of all data before it is functional. Only fetching and caching data on-demand will lead to the engine taking too long before it is running quickly enough. An external event can trigger the need for specific parts of the data to be reloaded. Basically, I think I need a combination of pushing and pulling data into the application. A simplified version of my current "pattern" looks like this (in psuedo-C# written in notepad): // This interface is implemented by all classes that needs the data interface IDataSubscriber { void RegisterData(Entity data); } // This interface is implemented by the data access class interface IDataProvider { void EnsureLoaded(Key dataKey); void RegisterSubscriber(IDataSubscriber subscriber); } class MyClassThatNeedsData : IDataSubscriber { IDataProvider _provider; MyClassThatNeedsData(IDataProvider provider) { _provider = provider; _provider.RegisterSubscriber(this); } public void RegisterData(Entity data) { // Save data for later StoreDataInCache(data); } void UseData(Key key) { // Make sure that the data has been stored in cache _provider.EnsureLoaded(key); Entity data = GetDataFromCache(key); } } class MyDataProvider : IDataProvider { List<IDataSubscriber> _subscribers; // Make sure that the data for key has been loaded to all subscribers public void EnsureLoaded(Key key) { if (HasKeyBeenMarkedAsLoaded(key)) return; PublishDataToSubscribers(key); MarkKeyAsLoaded(key); } // Force all subscribers to get a new version of the data for key public void ForceReload(Key key) { PublishDataToSubscribers(key); MarkKeyAsLoaded(key); } void PublishDataToSubscribers(Key key) { Entity data = FetchDataFromStore(key); foreach(var subscriber in _subscribers) { subscriber.RegisterData(data); } } } // This class will be spun off on startup and should make sure that all data is // preloaded as quickly as possible class MyPreloadingThread { IDataProvider _provider; MyPreloadingThread(IDataProvider provider) { _provider = provider; } void RunInBackground() { IEnumerable<Key> allKeys = GetAllKeys(); foreach(var key in allKeys) { _provider.EnsureLoaded(key); } } } I have a feeling though that this is not necessarily the best way of doing this.. Just the fact that explaining it seems to take two pages feels like an indication.. Any ideas? Any patterns out there I should have a look at?

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  • Web Services API Versioning

    - by Paul Izzy
    I offer a small Web Services API to my clients which I plan to evolve over time. So I need some sort of versioning, but I can't find any information about how you do something like that. Is there a best practise? How can I keep adding new functionality without breaking compatibility with the web services consumers?

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  • How do you search between two columns using a parameter and a case when statement? SQL Server

    - by Kip Birgen
    I would like to search between to columns in a s query or a table depending on the variable on a paramenter e.g Declare @SelectAll as interger Set @SelectAll = 1 Declare @Column as interger Select mt.Column1, mtColumn2 From MyTable as mt Where Case When @SelectAll = 1 Then mt.Column1 IN(@Column) and mt.Column2 (' Selecting all") When @SelectAll = 1 Then mt.Column2 IN(@Column) and mt.Column1 (' Selecting all") End The purpose of this query is to allow the user to search between the column they choose. Further more the use of parameter is for the purposes of writing reporting services reports.

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  • Data access pattern, combining push and pull?

    - by andlju
    I need some advice on what kind of pattern(s) I should use for pushing/pulling data into my application. I'm writing a rule-engine that needs to hold quite a large amount of data in-memory in order to be efficient enough. I have some rather conflicting requirements; It is not acceptable for the engine to always have to wait for a full pre-load of all data before it is functional. Only fetching and caching data on-demand will lead to the engine taking too long before it is running quickly enough. An external event can trigger the need for specific parts of the data to be reloaded. Basically, I think I need a combination of pushing and pulling data into the application. A simplified version of my current "pattern" looks like this (in psuedo-C# written in notepad): // This interface is implemented by all classes that needs the data interface IDataSubscriber { void RegisterData(Entity data); } // This interface is implemented by the data access class interface IDataProvider { void EnsureLoaded(Key dataKey); void RegisterSubscriber(IDataSubscriber subscriber); } class MyClassThatNeedsData : IDataSubscriber { IDataProvider _provider; MyClassThatNeedsData(IDataProvider provider) { _provider = provider; _provider.RegisterSubscriber(this); } public void RegisterData(Entity data) { // Save data for later StoreDataInCache(data); } void UseData(Key key) { // Make sure that the data has been stored in cache _provider.EnsureLoaded(key); Entity data = GetDataFromCache(key); } } class MyDataProvider : IDataProvider { List<IDataSubscriber> _subscribers; // Make sure that the data for key has been loaded to all subscribers public void EnsureLoaded(Key key) { if (HasKeyBeenMarkedAsLoaded(key)) return; PublishDataToSubscribers(key); MarkKeyAsLoaded(key); } // Force all subscribers to get a new version of the data for key public void ForceReload(Key key) { PublishDataToSubscribers(key); MarkKeyAsLoaded(key); } void PublishDataToSubscribers(Key key) { Entity data = FetchDataFromStore(key); foreach(var subscriber in _subscribers) { subscriber.RegisterData(data); } } } // This class will be spun off on startup and should make sure that all data is // preloaded as quickly as possible class MyPreloadingThread { IDataProvider _provider; MyPreloadingThread(IDataProvider provider) { _provider = provider; } void RunInBackground() { IEnumerable<Key> allKeys = GetAllKeys(); foreach(var key in allKeys) { _provider.EnsureLoaded(key); } } } I have a feeling though that this is not necessarily the best way of doing this.. Just the fact that explaining it seems to take two pages feels like an indication.. Any ideas? Any patterns out there I should have a look at?

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  • Import csv data (SDK iphone)

    - by Ni
    I am new to cocoa. I have been working on these stuff for a few days. For the following code, i can read all the data in the string, and successfully get the data for plot. NSMutableArray *contentArray = [NSMutableArray array]; NSString *filePath = @"995,995,995,995,995,995,995,995,1000,997,995,994,992,993,992,989,988,987,990,993,989"; NSArray *myText = [filePath componentsSeparatedByString:@","]; NSInteger idx; for (idx = 0; idx < myText.count; idx++) { NSString *data =[myText objectAtIndex:idx]; NSLog(@"%@", data); id x = [NSNumber numberWithFloat:0+idx*0.002777778]; id y = [NSDecimalNumber decimalNumberWithString:data]; [contentArray addObject: [NSMutableDictionary dictionaryWithObjectsAndKeys:x, @"x", y, @"y", nil]]; } self.dataForPlot = contentArray; then, i try to load the data from csv file. the data in Data.csv file has the same value and the same format as 995,995,995,995,995,995,995,995,1000,997,995,994,992,993,992,989,988,987,990,993,989. I run the code, it is supposed to give the same graph output. however, it seems that the data is not loaded from csv file successfully. i can not figure out what's wrong with my code. NSMutableArray *contentArray = [NSMutableArray array]; NSString *filePath = [[NSBundle mainBundle] pathForResource:@"Data" ofType:@"csv"]; NSString *Data = [NSString stringWithContentsOfFile:filePath encoding:NSUTF8StringEncoding error:nil ]; if (Data) { NSArray *myText = [Data componentsSeparatedByString:@","]; NSInteger idx; for (idx = 0; idx < myText.count; idx++) { NSString *data =[myText objectAtIndex:idx]; NSLog(@"%@", data); id x = [NSNumber numberWithFloat:0+idx*0.002777778]; id y = [NSDecimalNumber decimalNumberWithString:data]; [contentArray addObject: [NSMutableDictionary dictionaryWithObjectsAndKeys:x, @"x", y, @"y",nil]]; } self.dataForPlot = contentArray; } The only difference is NSString *filePath = [[NSBundle mainBundle] pathForResource:@"Data" ofType:@"csv"]; NSString *Data = [NSString stringWithContentsOfFile:filePath encoding:NSUTF8StringEncoding error:nil ]; if (data){ } did i do anything wrong here?? Thanks for your help!!!!

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  • Web Services Primer for a WinForms Developer?

    - by Unicorns
    I've been writing client/server applications with Winforms for about six years now, but I have yet to venture into the web space (neither ASP.NET nor web services). Given the direction that the job market has been heading for some time and the fact that I have a basic curiosity, I'd like to get involved with writing web services, but I don't know where to start. I've read about various options (XML/SOAP vs. JSON, REST vs...well, actually I don't know what it's called, etc.), but I'm not sure what sort of criteria are in play when making the determination to use one or the other. Obviously, I'd like to leverage the tools that I have (Visual Studio, the .NET framework, etc.) without hamstringing myself into only targeting a particular audience (i.e. writing the service in such a way as to make it difficult to consume from a Windows Mobile/Android/iPhone client, for example). For the record, my plan--for now--is to use WCF for my web service development, but I'm open to using another .NET approach if that's advisable. I realize that this question is pretty open-ended so it may get closed, but here are some things I'm wondering: What are some things to consider when choosing the type of web service (REST, etc.) I intend to write? Is it possible (and, if so, feasible) to move from one approach to another? Can web services be written in an event-driven way? As I said I'm a Winforms developer, so I'm used to objects raising events for me to react to. For instance, if I have two clients connected to my service, is there a way for me to "push" information to one of them as a result of an action by the other? If this is possible, is this advisable or am I just not thinking about it correctly? What authentication mechanisms seem to work best for public-facing services? What about if I plan to have different types of OS'es and clients connecting to the service? Is there a generally accepted platform-agnostic approach? In the line of authentication, is this something that I should be doing myself (authenticating an managing sessions, etc.) or is this something should be handled at the framework level and I just define exactly how it should work? If that's the case, how do I tell who the requester has authenticated themselves as? I started writing an authentication mechanism (simple username/password combinations stored in the database and a corresponding session table with a GUID key) within my service and just requiring that key to be passed with every operation (other than logging in, of course), but I want to make sure that I'm not reinventing the wheel here. However, I also don't want to clutter up the server with a bunch of machine user accounts just to use Basic authentication. I'm also under the impression that Digest (and of course Windows) authentication requires a machine (or AD) user account.

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  • Mysterious constraints problem with SQL Server 2000

    - by Ramon
    Hi all I'm getting the following error from a VB NET web application written in VS 2003, on framework 1.1. The web app is running on Windows Server 2000, IIS 5, and is reading from a SQL server 2000 database running on the same machine. System.Data.ConstraintException: Failed to enable constraints. One or more rows contain values violating non-null, unique, or foreign-key constraints. at System.Data.DataSet.FailedEnableConstraints() at System.Data.DataSet.EnableConstraints() at System.Data.DataSet.set_EnforceConstraints(Boolean value) at System.Data.DataTable.EndLoadData() at System.Data.Common.DbDataAdapter.FillFromReader(Object data, String srcTable, IDataReader dataReader, Int32 startRecord, Int32 maxRecords, DataColumn parentChapterColumn, Object parentChapterValue) at System.Data.Common.DbDataAdapter.Fill(DataSet dataSet, String srcTable, IDataReader dataReader, Int32 startRecord, Int32 maxRecords) at System.Data.Common.DbDataAdapter.FillFromCommand(Object data, Int32 startRecord, Int32 maxRecords, String srcTable, IDbCommand command, CommandBehavior behavior) at System.Data.Common.DbDataAdapter.Fill(DataSet dataSet, Int32 startRecord, Int32 maxRecords, String srcTable, IDbCommand command, CommandBehavior behavior) at System.Data.Common.DbDataAdapter.Fill(DataSet dataSet) The problem appears when the web app is under a high load. The system runs fine when volume is low, but when the number of requests becomes high, the system starts rejecting incoming requests with the above exception message. Once the problem appears, very few requests actually make it through and get processed normally, about 2 in every 30. The vast majority of requests fail, until a SQL Server restart or IIS reset is performed. The system then start processing requests normally, and after some time it starts throwing the same error. The error occurs when a data adapter runs the Fill() method against a SELECT statement, to populate a strongly-typed dataset. It appears that the dataset does not like the data it is given and throws this exception. This error occurs on various SELECT statements, acting on different tables. I have regenerated the dataset and checked the relevant constraints, as well as the table from which the data is read. Both the dataset definition and the data in the table are fine. Admittedly, the hardware running both the web app and SQL Server 2000 is seriously outdated, considering the numbers of incoming requests it currently receives. The amount of RAM consumed by SQL Server is dynamically allocated, and at peak times SQL Server can consume up to 2.8 GB out of a total of 3.5 GB on the server. At first I suspected some sort of index or database corruption, but after running DBCC CHECKDB, no errors were found in the database. So now I'm wondering whether this error is a result of the hardware limitations of the system. Is it possible for SQL Server to somehow mess up the data it's supposed to pass to the dataset, resulting in constraint violation due to, say, data type/length mismatch? I tried accessing the RowError messages of the data rows in the retrieved dataset tables but I kept getting empty strings. I know that HasErrors = true for the datatables in question. I have not set the EnableConstraints = false, and I don't want to do that. Thanks in advance. Ray

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  • WCF v.s. legacy ASP.Net Web Services

    - by George2
    Duplicate: although this is a good discussion, this is a duplicate of Web Services — WCF vs. Standard. Please consider adding any new information to the earlier question and closing this one. Could anyone recommend me some documents to describe why WCF is better than legacy ASP.Net web services? I am especially interested in performance and security. Thanks!

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  • How do I set a SQL Server 2008 Reporting Services Template to a Default Font?

    - by David Stein
    I'm creating a new template to create reports from at a later date. I know how to create one, and I know where to save it. However, the problem is this. Everything that is created on the report uses the default font of Arial with a size of 10pt. I need to set mine to default to Tahoma 11pt. I can create a mock title, mock tables, etc and save those to Tahoma 11pt, but any new controls that are used on any version of this report will default back to Arial 10pt. How do I fix this?

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  • Accessing Amazon E-Commerce Services through Cocoa Touch

    - by Gregory Hill
    Has anyone successfully accessed AWS (Amazon E-Commerce Services) through Cocoa Touch? I've been digging around, and haven't seen the issue addressed directly. I've created an AWS account, and have seen some sample code for accessing web services through Cocoa, but I'm not quite sure how to tie it all together. If anyone has any sample code, I'd love to see it. I'm just trying to get my head around the concepts.

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  • Can Django be used for web services?

    - by alex
    My friend said, "Pylons is so much better for web services." My other friend said, "You can modify Django in a way to do exactly whatever you like." In Django, what is necessary to be modified (urls.py? models classes? settings?) in order to do "web services" with APIs and REST and versioning, etc etc.?

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  • Web Services, Memory Leaks and CRM

    - by Neil
    Hi, I have a website that allows users to upload a csv file. This calls a service that reads the information from the csv, puts it into DynamicEntity objects and calls the CRM service to Create/Update entities in CRM. When this service creates/updates an entity this kicks off other plugins to apply certain business rules. These rules can also Create or Update entites in CRM. The issue here is that the handle count of the w3wp.exe process that the website is calling increases every time the an entity is created or updated and it never comes back down. I tried putting Garbage Collection code in the business rules and this reduces the handle count of the CRM w3wp process (run by the Network Service), but not the other w3wp process. Should I have Dispose methods on the Web Service that calls the CRM service? I hope that makes sense. I'm not overly familiar with memory management issues so any help is appreciated. Can anybody give me some tips on how to stop this from occurring? Thanks, Neil -- EDIT Okay well the handle count goes up when I call the Service.Create(DynamicEntity) method. I don't think placing any code here would be beneficial. When I exit the method/class/service that contains this call the handle count stays as it is. What I need to know is whether this is something I should be managing or is it something CRM takes care of (or doesn't take care of but I can't do anything about it) -- Another Edit Right this is how it works. 1) We have CRM and its related services 2) We have another service independent of CRM that uses the CRM services (number 1 above) to create entities based on csv info passed into it 3) We have a website that allows a user to upload a csv, and calls service no 2 above to Create/Update entities in CRM 4) We have plugins fired by CRM which use Service 1 above to create/update entities So the user uploads a csv to the website (3), this fires a service(2). When service 2 creates an entity using service 1, Service 4 fires. Service 4 calls also uses service 1 to Create entities, and when these services are called (using the Service.Create() method) the handle count of the process increases. When the method/class/services finish the handle count remains the same, and so when the whole process occurs again the handle count will increased again.

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  • web services & php

    - by pareja
    Hi... I need help because I don't know about web services using php somebody help me I need to create a web services with php and I need some any reference (free) Thanks for your help

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  • what are software and hardware requirement for building REST web services in java

    - by user1846545
    I want to build rest web services in java. can some body tell me what are the software and hardware requirements for that? I want to know it in sense like one computer, which one database and which one server and if any other because i want to use these web services globally and want to post JSON in request and also want to get response in json for an android app. thanx, any answer would be a great help for me.

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  • Why should I prefer OSGi Services over exported packages?

    - by Jens
    Hi, I am trying to get my head around OSGi Services. The main question I keep asking myself is: What's the benefit of using services instead of working with bundles and their exported packages? As far as I know it seems the concept of Late Binding has something to do with it. Bundle dependencies are wired together at bundle start, so they are pretty fixed I guess. But with services it seems to be almost the same. A bundle starts and registers services or binds to services. Of course services can come and go whenever they want and you have to keep track of these chances. But the core idea doesn't seem that different to me. Another aspect to this seems to be that services are more flexible. There could be many implementations for one specific Interface. On the other hand there can be a lot of different implementations for a specific exported package too. In another text I read that the disadvantage of using exported packages is that they make the application more fragile than services. The author wrote that if you remove one bundle from the dependency graph other dependencies would no longer be met, thus possibly causing a domino effect on the whole graph. But couldn't the same happen if a service would go offline? To me it looks like service dependencies are no better than bundle dependencies. So far I could not find a blog post, book or presentation that could clearly describe why services are better than just exposing functionality by exporting and importing packages. To sum my questions up: What are the key benefits of using OSGi Services that make them superior to exporting and importing packages?

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