I have an application that is multilingual. I'm using the out-of-the-box .Net features for this. Each language has its own file in the App_GlobalResources (see iamge below)
In the code behind what is better?
GetGlobalResourceObject("LocalizedText", "ErrorOccured")
Resources.LocalizedText.ErrorOccured
The 2nd one uses less code and it's type safe, it will return an error during compile time and not run time.
alt text http://img340.imageshack.us/img340/5562/langl.gif
These are the advantages of each approach:
Advantages of GetGlobalResourceObject (and GetLocalResourceObject):
You can specify a particular culture instead of using the CurrentCulture.
You can use a late-bound expression (i.e. a string) to decide which resource to load. This is useful if you can't know ahead of time which resource you will need to load.
It works with any resource provider type. For example, it works not only with the built-in default RESX-based provider but it'll work the same against a database-based provider.
Advantages of strongly-typed RESX types:
You get compile-time errors if you access a resource that doesn't exist.
You get Intellisense while working on the project.
So, as with many "which is best" questions, the answer is: It depends! Choose the one that has advantages that will benefit your particular scenarios the most.
So use the second one, if you know up-front what the resource file and key will be.
The GetGlobalResourceObject() method is useful if you don't know what the resource file or (more likely) the key will be at compile time.
Related
Basically, I want to be able to generate class definitions, compile the system, and save it for reuse. Would that involve a code walker, or is there a simpler option?
(save-lisp-and-die "isn't going to work for me")
Expanding to explain. I'm generating systems based on OpenAPI definitions, so a system roughly corresponds to an API client.
There will be dozens, if not hundreds of these.
The idea is to NOT keep them all in the image, but load at run time as required.
I see two possible routes here, and to some extent, I suspect they mainly differ in "the last mile" (as it were).
The route you seem to have settled on, run-time definition of classes and functions.
A route whereby you generate your function/class forms, but don't go the full way to get them "Live" in the image and instead emit the form(s) to a file.
I suspect that it would be possible to have most of the generating code shared between the two and for the first route have a wrapping macro that effectively returns a PROGN, and in the second calls a function to pretty-print what the macro would have returned on a stream.
Saying that, building a tailored environment and saving it to a "core" file is a pretty good way of getting excellent startup times.
I have been trying to get culture specific resources to work on an asp.net mvc 3 application.
If I have a LanguageResources.resx and a LanguageResources.en-UK.resx in my App_GlobalResources folder then I get an error "The namespace 'Resources' already contains a definition for 'LanguageResources'"
This is the end of a long line of issues that I have had with trying to get culture specific resources to work. I must say, I'm not impressed with the documentation Microsoft provide for using this feature.
I'm considering using a database table to store my culture specific strings instead, then I can just build a dictionary of all the values that will be available to my controller and views.
Has anyone else made such a decision, or have any direct knowledge on performance issues related to using a database for culture specific strings?
Has anyone else given up on resources too?
I must admit, I tried to reproduce your defect and I was successful. It looks like, Visual Studio generates additional class when you add something.en-UK.resx. Strange. It should not allow you to add anything like this in the first place for there is no such culture.
How to resolve the problem? Just add LanguageResources.en-GB.resx and delete
LanguageResources.en-GB.resx. That helps.
I would not use database for storing language-related resources, unless they are changing very frequently or must be entered by end users (i.e. there are some kind of templates).
Using the database hurts Localizability and requires much effort. It is hard to design correctly (I have seen a lot of mistakes in that area). Don't go that road unless you really have to.
I'm conducting a project in which a website should have multi-language support.
Now, this website is supposed to serve about 500K+ visitors a day, so it must be super-efficient.
I've created a table of parameters {[ID],[Name]} AND a linkage-table {[objectID],[parameterID],[languageID],[value]}. I think it's the best way to deploy multi-language support while having the privilege to translate different parameters for each language.
As far as I know, server's memory is much faster than a physical HDD. Therefore, I'm planning to store ASP.NET Application State objects for my translation architecture.
(http://msdn.microsoft.com/en-us/library/ms178594.aspx)
How does my plan sound so far? any suggestions?
If you are planning on making an app that support multiple languages, your instant reflex should be let .net do the work for you. What i'm reading in your question is that you are setting up something to support that. You should know that localization is the way to go when you want to develop a multi-language environment.
Take a look at this msdn article, it should give you a general idea on the topic.
So, localizing an application can be divided into two parts:
Localizing business logic entities.
Localizing everything else.
In the question I see words which are related to business entity localization. For that purpose I agree with the concept to have separation between entities and their localizations.
Part 1 - Localizing entities:
Personally I do this way in database:
table Entity {EntityID, Name} -this is the entity-related table.
table EntityByLang {EntityID, LanguageID, Name} -this is the localized version of the table for each supported language.
This way allows me to have default values for each localizable property like Name and its localization, if such is available in the localized table. What's left here up to you is - you need to implement the data-access-layer which takes the Name localized for the current user language, or the default value (if language or the translation is not available for the given language).
Part 2 - Localizing everything else:
Here, with no alternatives in terms of the performance, I would recommend using some kind of static resources. Personally I live with static resources available for standard asp.net applications.
From the architectural point of view, don't directly refer to localization code from your UI code, like this (which I don't like):
var translation = HttpContext.Current.GetGlobalResourceObject("hello");
//excuse me, if I don't exactly remember the GetGlobalResourceObject() method name...
Instead, I would recommend using this kind of approach:
var translation = AppContext.GetLocalizationService().Translate("hello");
Where: AppContext - some kind of facade/factory (in fact, implementation of abstract facade/factory). GetLocalizationService - initially returns some kind of ILocalizationService, when implemented it returns StaticResLocalizationService (which implements ILocalizationService). This way allowing switching from one kind of localization to another. And particularly StaticResLocalizationService works with asp.net static resources
Sorry for messy sample codes, but I hope you understand my approach.
I hope this helps!
I would suggest to create custom resource provider, you can read more here:
http://msdn.microsoft.com/en-us/library/aa905797.aspx
with this model you can leverage existing asp .net localization functionality
We're currently migrating our ASP Intranet to .NET and we started to develop this Intranet in one ASP.NET website. This, however, raised some problems regarding Visual Studio (performance, compile-time, ...).
Because our Intranet basically exists of modules, we want to seperate our project in subprojects in Visual Studio (each module is a subproject).
This raises also some problems because the modules have references to each other.
Module X uses Module Y and vice versa... (circular dependencies).
What's the best way to develop such an Intranet?
I'll will give an example because it's difficult to explain.
We have a module to maintain our employees. Each employee has different documents (a contract, documents created by the employee, ...).
All documents inside our Intranet our maintained by a document module.
The employee-module needs to reference the document-module.
What if in the future I need to reference the employee-module in the document-module?
What's the best way to solve this?
It sounds to me like you have two problems.
First you need to break the business orientated functionality of the system down into cohesive parts; in terms of Object Orientated design there's a few principles which you should be using to guide your thinking:
Common Reuse Principle
Common Closure Principle
The idea is that things which are closely related, to the extent that 'if one needs to be changed, they all are likely to need to be changed'.
Single Responsibility Principle
Don't try to have a component do to much.
I think you also need to look at you dependency structure more closely - as soon as you start getting circular references it's probably a sign that you haven't broken the various "things" apart correctly. Maybe you need to understand the problem domain more? It's a common problem - well, not so much a problem as simply a part of designing complex systems.
Once you get this sorted out it will make the second part much easier: system architecture and design.
Luckily there's already a lot of existing material on plugins, try searching by tag, e.g:
https://stackoverflow.com/questions/tagged/plugins+.net
https://stackoverflow.com/questions/tagged/plugins+architecture
Edit:
Assets is defined in a different module than employees. But the Assets-class defines a property 'AssignedTo' which is of the type 'Employee'. I've been breaking my head how to disconnect these two
There two parts to this, and you might want to look at using both:
Using a Common Layer containing simple data structures that all parts of the system can share.
Using Interfaces.
Common Layer / POCO's
POCO stands for "Plain Old CLR Objects", the idea is that POCO's are a simple data structures that you can use for exchanging information between layers - or in your case between modules that need to remain loosely Coupled. POCO's don't contain any business logic. Treat them like you'd treat the String or DateTime types.
So rather than referencing each other, the Asset and Employee classes reference the POCO's.
The idea is to define these in a common assembly that the rest of your application / modules can reference. The assembly which defines these needs to be devoid of unwanted dependencies - which should be easy enough.
Interfaces
This is pretty much the same, but instead of referring to a concrete object (like a POCO) you refer to an interface. These interfaces would be defined in a similar fashion to the POCO's described above (common assembly, no dependencies).
You'd then use a Factory to go and load up the concrete object at runtime. This is basically Dependency Inversion.
So rather than referencing each other, the Asset and Employee classes reference the interfaces, and concrete implementations are instantiated at runtime.
This article might be of assistance for both of the options above: An Introduction to Dependency Inversion
Edit:
I've got the following method GetAsset( int assetID ); In this method, the property asset.AssignedTo (type IAssignable) is filled in. How can I assign this properly?
This depends on where the logic sits, and how you want to architect things.
If you have a Business Logic (BL) Layer - which is mainly a comprehensive Domain Model (DM) (of which both Asset and Employee were members), then it's likely Assets and Members would know about each other, and when you did a call to populate the Asset you'd probably get the appropriate Employee data as well. In this case the BL / DM is asking for the data - not isolated Asset and Member classes.
In this case your "modules" would be another layer that was built on top of the BL / DM described above.
I variation on this is that inside GetAsset() you only get asset data, and atsome point after that you get the employee data separately. No matter how loosely you couple things there is going to have to be some point at which you define the connection between Asset and Employee, even if it's just in data.
This suggests some sort of Register Pattern, a place where "connections" are defined, and anytime you deal with a type which is 'IAssignable' you know you need to check the register for any possible assignments.
I would look into creating interfaces for your plug-ins that way you will be able to add new modules, and as long as they follow the interface specifications your projects will be able to call them without explicitly knowing anything about them.
We use this to create plug-ins for our application. Each plugin in encapsulated in user control that implements a specific interface, then we add new modules whenever we want, and because they are user controls we can store the path to the control in the database, and use load control to load them, and we use the interface to manipulate them, the page that loads them doesn't need to know anything about what they do.
I am VERY new to ASP.NET. I come from a VB6 / ASP (classic) / SQL Server 2000 background. I am reading a lot about Visual Studio 2008 (have installed it and am poking around). I have read about "reflection" and would like someone to explain, as best as you can to an older developer of the technologies I've written above, what exactly Reflection is and why I would use it... I am having trouble getting my head around that. Thanks!
Reflection is how you can explore the internals of different Types, without normally having access (ie. private, protected, etc members).
It's also used to dynamically load DLL's and get access to types and methods defined in them without statically compiling them into your project.
In a nutshell: Reflection is your toolkit for peeking under the hood of a piece of code.
As to why you would use it, it's generally only used in complex situations, or code analysis. The other common use is for loading precompiled plugins into your project.
Reflection lets you programmatically load an assembly, get a list of all the types in an assembly, get a list of all the properties and methods in these types, etc.
As an example:
myobject.GetType().GetProperty("MyProperty").SetValue(myobject, "wicked!", null)
It allows the internals of an object to be reflected to the outside world (code that is using said objects).
A practical use in statically typed languages like C# (and Java) is to allow invocation of methods/members at runtime via a string (eg the name of the method - perhaps you don't know the name of the method you will use at compile time).
In the context of dynamic languages I haven't heard the term as much (as generally you don't worry about the above), other then perhaps to iterate through a list of methods/members etc...
Reflection is .Net's means to manipulate or extract information of an assembly, class or method at run time. For example, you can create a class at runtime, including it's methods. As stated by monoxide, reflection is used to dynamically load assembly as plugins, or in advance cases, it is used to create .Net compiler targeting .Net, like IronPython.
Updated: You may refer to the topic on metaprogramming and its related topics for more details.
When you build any assembly in .NET (ASP.NET, Windows Forms, Command line, class library etc), a number of meta-data "definition tables" are also created within the assembly storing information about methods, fields and types corresponding to the types, fields and methods you wrote in your code.
The classes in System.Reflection namespace in .NET allow you to enumerate and interate over these tables, providing an "object model" for you to query and access items in these tables.
One common use of Reflection is providing extensibility (plug-ins) to your application. For example, Reflection allows you to load an assembly dynamically from a file path, query its types for a specific useful type (such as an Interface your application can call) and then actually invoke a method on this external assembly.
Custom Attributes also go hand in hand with reflection. For example the NUnit unit testing framework allows you to indicate a testing class and test methods by adding [Test] {TestFixture] attributes to your own code.
However then the NUnit test runner must use Reflection to load your assembly, search for all occurrences of methods that have the test attribute and then actually call your test.
This is simplifying it a lot, however it gives you a good practical example of where Reflection is essential.
Reflection certainly is powerful, however be ware that it allows you to completely disregard the fundamental concept of access modifiers (encapsulation) in object oriented programming.
For example you can easily use it to retrieve a list of Private methods in a class and actually call them. For this reason you need to think carefully about how and where you use it to avoid bypassing encapsulation and very tightly coupling (bad) code.
Reflection is the process of inspecting the metadata of an application. In other words,When reading attributes, you’ve already looked at some of the functionality that reflection
offers. Reflection enables an application to collect information about itself and act on this in-
formation. Reflection is slower than normally executing static code. It can, however, give you
a flexibility that static code can’t provide