Why two different WorkflowServiceHost classes - .net-4.0

I was wondering why there are two different WorkflowServiceHost class implementation in following namespaces
1. System.ServiceModel
2. System.ServiceModel.Activities
What are the purpose of these different implementation?
IMO different names would be better. It creates a lot of confusion.

This is because in the .NET 4 framework there are 2 different workflow stacks.
The System.ServiceModel.Activities namespace contains the WF4 version.
The System.ServiceModel namespace contains the WF3 version.
And the same is true for other classes like Activity where there are multiple version. Different class names might help but they do have the same purpose. And namespaces are there to solve these kinds of differences.

Related

Using Autofac in Ninject

Hello I have many many projects in many solutions and all use Ninject as IoC container. Common libraries have Ninject modules, the applications (like console application) usually have modules too and combine the modules in one StandardKernel. Now I have to change all common libraries to Autofac.
Let's say I make modifications and use Autofac (by defining Autofac modules) in a project named A (common library). A is referenced in project B (a console application) which still uses Ninject. Let's assume that for now I do not want to modify project B too much and I want to leave Ninject there.
It is possible to use Autofac modules from project A when in the end I use Ninject's StandardKernel in the "final" project B?
To the best of my knowledge there is no adapter that just "converts" one IoC format to the other. I don't think Ninject supports Microsoft.Extensions.DependencyInjection format registrations, either, so trying to use the IServiceCollection from there as a bridge also won't work.
Unfortunately, I think you're stuck. You'll have to do it all at once. Sorry.

Strange namespacing in .net core

in Visual Studio 2017 I have a solution with aspnet core project and about 10 net core libraries referenced to each other.
One of the libraries is xUnit test project. It referenced to another project it should use as aim for testing.
For example I have:
Project: MyProject.Domain
Test Project: MyProject.Domain.Tests
MyProject.Domain.Tests is referenced to MyProject.Domain.
In these projects I have classes with namespaces like project names.
So the strange thing happened when I can use public class from MyProject.Domain WITHOUT using MyProject.Domain.
Can anybody explain it ?
If I understand you correctly, you're wondering why a type in the namespace MyProject.Domain.Tests can access types in the namespace MyProject.Domain without any usings. The reason for that is that the specification says so. From Namespace and type names (edited by removing irrelevant parts):
The meaning of a namespace_or_type_name is determined as follows:
If the namespace_or_type_name is of the form I:
For each namespace N, starting with the namespace in which the namespace_or_type_name
occurs, continuing with each enclosing namespace (if any), and ending
with the global namespace, the following steps are evaluated until an
entity is located:
If N contains an accessible type having name I, then:
The namespace_or_type_name refers to the type.

Where is ProviderBase in .NET 5?

We have many projects based on the provider model/pattern. (Reading files from various sources, create reports from various sources, etc.) I have been unable to find anything equivalent to the ProviderBase in .net 5. We need an abstract interface/class that can be configured at runtime.
I suspect ProviderBase is something we will never see in ASP.NET 5 and beyond. Configuration is simpler in 5, and dependency injection is prevalent. Now you can create a class implementing your own custom interface and not have forced inheritance from ProviderBase. You can register the class or an instance of the class with a container and it will appear throughout the application. It might look like a bit more work at first, but I also suspect embracing DI will result in less code, and simpler code.

Include Extension Methods in Generated Proxies File

We have two assemblies, DataContracts and Core. We are currently using svcutil to generate our DataContracts, while referencing Core. We've got a couple of extension methods on different enum types that would be useful on the client side.
Is there any way to get svcutil to include these extension methods into our generated proxies file?
Any methods that you want exposed you need to have as part of the operational contract. I don't know of any other way to expose the metadata in the WSDL without learning more about how the WSDLImporter works. Irregardless - Metadata is only contracts - you can't share operations/behaviors in your metadata. The only way to share method behaviors (your extensions) is to include them in the shared contract/core assembly or expose them as operation contracts.
The classes generated by svcutil are partial. Therefore the functionality of those classes can be split in multiple files. One file is the one generated by the svcutil with the functionality exposed by the service. Other files could contain the functionality you want to append, which is not part of the data contract.
More info on partial classes Partial Classes and Methods (C# Programming Guide) on MSDN

In what namespace should you put interfaces relative to their implementors?

Specifically, when you create an interface/implementor pair, and there is no overriding organizational concern (such as the interface should go in a different assembly ie, as recommended by the s# architecture) do you have a default way of organizing them in your namespace/naming scheme?
This is obviously a more opinion based question but I think some people have thought about this more and we can all benefit from their conclusions.
The answer depends on your intentions.
If you intend the consumer of your namespaces to use the interfaces over the concrete implementations, I would recommend having your interfaces in the top-level namespace with the implementations in a child namespace
If the consumer is to use both, have them in the same namespace.
If the interface is for predominantly specialized use, like creating new implementations, consider having them in a child namespace such as Design or ComponentModel.
I'm sure there are other options as well, but as with most namespace issues, it comes down to the use-cases of the project, and the classes and interfaces it contains.
I usually keep the interface in the same namespace of as the concrete types.
But, that's just my opinion, and namespace layout is highly subjective.
Animals
|
| - IAnimal
| - Dog
| - Cat
Plants
|
| - IPlant
| - Cactus
You don't really gain anything by moving one or two types out of the main namespace, but you do add the requirement for one extra using statement.
What I generally do is to create an Interfaces namespace at a high level in my hierarchy and put all interfaces in there (I do not bother to nest other namespaces in there as I would then end up with many namespaces containing only one interface).
Interfaces
|--IAnimal
|--IVegetable
|--IMineral
MineralImplementor
Organisms
|--AnimalImplementor
|--VegetableImplementor
This is just the way that I have done it in the past and I have not had many problems with it, though admittedly it might be confusing to others sitting down with my projects. I am very curious to see what other people do.
I prefer to keep my interfaces and implementation classes in the same namespace. When possible, I give the implementation classes internal visibility and provide a factory (usually in the form of a static factory method that delegates to a worker class, with an internal method that allows a unit tests in a friend assembly to substitute a different worker that produces stubs). Of course, if the concrete class needs to be public--for instance, if it's an abstract base class, then that's fine; I don't see any reason to put an ABC in its own namespace.
On a side note, I strongly dislike the .NET convention of prefacing interface names with the letter 'I.' The thing the (I)Foo interface models is not an ifoo, it's simply a foo. So why can't I just call it Foo? I then name the implementation classes specifically, for example, AbstractFoo, MemoryOptimizedFoo, SimpleFoo, StubFoo etc.
(.Net) I tend to keep interfaces in a separate "common" assembly so I can use that interface in several applications and, more often, in the server components of my apps.
Regarding namespaces, I keep them in BusinessCommon.Interfaces.
I do this to ensure that neither I nor my developers are tempted to reference the implementations directly.
Separate the interfaces in some way (projects in Eclipse, etc) so that it's easy to deploy only the interfaces. This allows you to provide your external API without providing implementations. This allows dependent projects to build with a bare minimum of externals. Obviously this applies more to larger projects, but the concept is good in all cases.
I usually separate them into two separate assemblies. One of the usual reasons for a interface is to have a series of objects look the same to some subsystem of your software. For example I have all my Reports implementing the IReport Interfaces. IReport is used is not only used in printing but for previewing and selecting individual options for each report. Finally I have a collection of IReport to use in dialog where the user selects which reports (and configuring options) they want to print.
The Reports reside in a separate assembly and the IReport, the Preview engine, print engine, report selections reside in their respective core assembly and/or UI assembly.
If you use the Factory Class to return a list of available reports in the report assembly then updating the software with new report becomes merely a matter of copying the new report assembly over the original. You can even use the Reflection API to just scan the list of assemblies for any Report Factories and build your list of Reports that way.
You can apply this techniques to Files as well. My own software runs a metal cutting machine so we use this idea for the shape and fitting libraries we sell alongside our software.
Again the classes implementing a core interface should reside in a separate assembly so you can update that separately from the rest of the software.
I give my own experience that is against other answers.
I tend to put all my interfaces in the package they belongs to. This grants that, if I move a package in another project I have all the thing there must be to run the package without any changes.
For me, any helper functions and operator functions that are part of the functionality of a class should go into the same namespace as that of the class, because they form part of the public API of that namespace.
If you have common implementations that share the same interface in different packages you probably need to refactor your project.
Sometimes I see that there are plenty of interfaces in a project that could be converted in an abstract implementation rather that an interface.
So, ask yourself if you are really modeling a type or a structure.
A good example might be looking at what Microsoft does.
Assembly: System.Runtime.dll
System.Collections.Generic.IEnumerable<T>
Where are the concrete types?
Assembly: System.Colleections.dll
System.Collections.Generic.List<T>
System.Collections.Generic.Queue<T>
System.Collections.Generic.Stack<T>
// etc
Assembly: EntityFramework.dll
System.Data.Entity.IDbSet<T>
Concrete Type?
Assembly: EntityFramework.dll
System.Data.Entity.DbSet<T>
Further examples
Microsoft.Extensions.Logging.ILogger<T>
- Microsoft.Extensions.Logging.Logger<T>
Microsoft.Extensions.Options.IOptions<T>
- Microsoft.Extensions.Options.OptionsManager<T>
- Microsoft.Extensions.Options.OptionsWrapper<T>
- Microsoft.Extensions.Caching.Memory.MemoryCacheOptions
- Microsoft.Extensions.Caching.SqlServer.SqlServerCacheOptions
- Microsoft.Extensions.Caching.Redis.RedisCacheOptions
Some very interesting tells here. When the namespace changes to support the interface, the namespace change Caching is also prefixed to the derived type RedisCacheOptions. Additionally, the derived types are in an additional namespace of the implementation.
Memory -> MemoryCacheOptions
SqlServer -> SqlServerCatchOptions
Redis -> RedisCacheOptions
This seems like a fairly easy pattern to follow most of the time. As an example I (since no example was given) the following pattern might emerge:
CarDealership.Entities.Dll
CarDealership.Entities.IPerson
CarDealership.Entities.IVehicle
CarDealership.Entities.Person
CarDealership.Entities.Vehicle
Maybe a technology like Entity Framework prevents you from using the predefined classes. Thus we make our own.
CarDealership.Entities.EntityFramework.Dll
CarDealership.Entities.EntityFramework.Person
CarDealership.Entities.EntityFramework.Vehicle
CarDealership.Entities.EntityFramework.SalesPerson
CarDealership.Entities.EntityFramework.FinancePerson
CarDealership.Entities.EntityFramework.LotVehicle
CarDealership.Entities.EntityFramework.ShuttleVehicle
CarDealership.Entities.EntityFramework.BorrowVehicle
Not that it happens often but may there's a decision to switch technologies for whatever reason and now we have...
CarDealership.Entities.Dapper.Dll
CarDealership.Entities.Dapper.Person
CarDealership.Entities.Dapper.Vehicle
//etc
As long as we're programming to the interfaces we've defined in root Entities (following the Liskov Substitution Principle) down stream code doesn't care where how the Interface was implemented.
More importantly, In My Opinion, creating derived types also means you don't have to consistently include a different namespace because the parent namespace contains the interfaces. I'm not sure I've ever seen a Microsoft example of interfaces stored in child namespaces that are then implement in the parent namespace (almost an Anti-Pattern if you ask me).
I definitely don't recommend segregating your code by type, eg:
MyNamespace.Interfaces
MyNamespace.Enums
MyNameSpace.Classes
MyNamespace.Structs
This doesn't add value to being descriptive. And it's akin to using System Hungarian notation, which is mostly if not now exclusively, frowned upon.
I HATE when I find interfaces and implementations in the same namespace/assembly. Please don't do that, if the project evolves, it's a pain in the ass to refactor.
When I reference an interface, I want to implement it, not to get all its implementations.
What might me be admissible is to put the interface with its dependency class(class that references the interface).
EDIT: #Josh, I juste read the last sentence of mine, it's confusing! of course, both the dependency class and the one that implements it reference the interface. In order to make myself clear I'll give examples :
Acceptable :
Interface + implementation :
namespace A;
Interface IMyInterface
{
void MyMethod();
}
namespace A;
Interface MyDependentClass
{
private IMyInterface inject;
public MyDependentClass(IMyInterface inject)
{
this.inject = inject;
}
public void DoJob()
{
//Bla bla
inject.MyMethod();
}
}
Implementing class:
namespace B;
Interface MyImplementing : IMyInterface
{
public void MyMethod()
{
Console.WriteLine("hello world");
}
}
NOT ACCEPTABLE:
namespace A;
Interface IMyInterface
{
void MyMethod();
}
namespace A;
Interface MyImplementing : IMyInterface
{
public void MyMethod()
{
Console.WriteLine("hello world");
}
}
And please DON'T CREATE a project/garbage for your interfaces ! example : ShittyProject.Interfaces. You've missed the point!
Imagine you created a DLL reserved for your interfaces (200 MB). If you had to add a single interface with two line of codes, your users will have to update 200 MB just for two dumb signaturs!