I am testing some WCF service. What I want to is to have a object generator for given classes. Then I will send the object as parameter to WCF service. It need to traverse the (nested) data member of the class and do data generate for each of them of different data types. It's great if it can be defined some rules e.g. certain data member can only have the value from a enum.
Could some one give me some direction on this?
Related
We are building a real-estate portal. We have Services, Mappers and Entites. At the stage we are allowing users to either
Create a property via a form.
Upload a batch file containing 1 or more properties.
So if he create a property via the form we can validate the form and if its a valid property, we can add it into our system. But if he upload via a batch file, we think that the responsibility of the form is
to validate that the user provided a file
the file type is valid
and the file size is within the allowed limits.
After this it should hand over the file to the controller or service.
Now the pending tasks are
Process the file and retrieve the contents
Validate the contents
If validated, save the properties or display an error.
So which part(s) are responsible for the above tasks?
I am thinking that the controller should do the initial file processing and pass the data to the service. This means that we will create/fetch the form object in the controller and validate the form within the controller.
Now the next section is to validate the contents, which is actually a collection of entities. So we have following ideas for this stage
Service will validate the data and create the entities, it will save them.
Or service will create the entity with the provided data and then call the validation function of the entity.
Or the service will try to create an entity with the provided data (send the data to the entity constructor), and if the data is valid, the entity will be created or will generate an error etc.
The possible issues I can think about above approaches are
If the service is validating the data, it means the service will know the inner structure of the entity, so if down the road we need to update the entity structure, we have to update the service as well. Which will introduce some sort of dependency.
In the 2nd approach, I don't think that an entity should be created at first place if it isn't valid.
In the 3rd approach, we are creating a functionality within entity's constructor, so making the entity dependent on the data. So when we need to fetch the entity from persistent, we need to provide some stub data.
Or am I over-thinking??
Now the next section is to validate the contents, which is actually a collection of entities.
The Contents, that Controller sends to Service, is a graph of objects / a structure / a plain string in the simplest case, but never a collection of business entities.
If the service is validating the data, it means the service will know the inner structure of the entity
What exactly is Service validating?
Service is validating the data means that Service ensures invariant of every structure / object that it receives.
For example, if F(T) is service method and T is structure with properties { A, B, C } that represents a triangle with three edges, then Service has to ensure the invariants (the length of each site is greater then zero and the sum of the lengths of any two sides must be greater than the length of the third side) of this structure after this structure has been deserialized.
This validation has to be done because deserializer doesn't use constructors to ensure invariants during deserialization.
When these validations are done, all objects passed to Service are valid and can be freely used in business layer directly or converted to objects (for example, entities) known to business layer.
if down the road we need to update the entity structure, we have to update the service as well. Which will introduce some sort of dependency.
This dependency is inavoidable. Since Transfer Objects and Entity Objects are separated, there always exists mapper that knows how to convert them.
Service will validate the data and create the entities, it will save them.
I'd go with this. Service validates data, converts into business layer objects, invokes business layer functions, persists changes.
It depends on what kind of constraints you're validating.
1.parameter validation like notEmpty property name or max length etc.
In this case you could extract the validation logic to a Validator object. This is useful when you have multiple property creating form(web form, file uploading), the validator may be invoked by multiple "client", but the validation logic keeps in one object.
2.business rule validation.
I prefer using domain models, you may have a look at the PhoneNumber example in this presentation
Suppose this simple scenario:
My client has an already working .net application and he/she wants to expose some functionality through WCF. So he gives me an assembly, containg a public class that exposes the followig method.
OrderDetail GetOrderDetail (int orderId) // Suppose OrderDetail has {ProductId, Quantity, Amount)
Now, I want some members of OrderDetail (Amount) not to be serialized.
According to http://msdn.microsoft.com/en-us/library/aa738737.aspx, the way to do this is by means of the [DataContract] and [DataMember]/[IgnoreDataMember] attributes. However, that's not an option for me because I can not modify client's source code. So I'm looking for a way to specify which members I want to serialize out, outside the type's definition. Something that should look like this:
[OperationContract]
[IgnoreMember(typeof(OrderDetail), "Amount" )]
OrderDetail QueryOrder(int orderId){
return OrderDetail.GetOrderDetail(orderId)
}
Is there any way to to this?
Thanks,
Bernabé
Don't send the clients objects across the wire, create a DTO from the clients object containing only the information that you want to send and send that instead.
This allows you to control exactly what information gets sent, and is in keeping with the WCF intentions of passing messages and not objects
So create an OrderDetailDto class and populate this with the data from the OrderDetail returned by the call to the method in the clients code. Decorate The OrderDetailDto with the DataContract and DataMember attributes (you can rename the class in here so that when it is returned by WCF it is returned with the name OrderDetail)
Repeat this for all objects in the client code, so that at the service boundary you basically convert from DTO->Client objects and Client Objects->DTO
EDIT
Whilst there might be an option which allows what you have asked for (I am not aware of one, but hopefully someone else might be) consider that when you send use your client objects as DTOs you are using them for two purposes (the client object and the message contract), which is against the Single Responsibility Principle and when you get them on the client side they will not be the same client side objects, just DTOs with the same properties, you will not be able to get behaviour in the client side objects (at least not without sharing libraries on the server side and client side).
By binding the data contract to the objects you also end up having to manage the changes to client objects and data contracts as one thing. When they are separate you can manage the changes to client side objects without neccessarily changing the DTOs, you can just populate the differently.
Whilst it seems like it is a lot of work to create the DTOs, in the end I think it will be worth it.
You will have to write a wrapper class that only exposes the desired properties and simply calls the class your client provided to gets its values.
The only other option would be to emit a new dynamic class using reflection and serialize that (see http://msdn.microsoft.com/en-us/library/system.reflection.emit.typebuilder.aspx), but its probably not worth the effort unless you need to build a lot of wrapper classes.
I have a server side service called ConstructionManager, one of its operation is GetAll() which return a list of constructions. Construction is a data contract, and there are several types which inherit from Construction (Buildings, Apartments etc..)
When I send the list of apartments all is good, all properties is on their place, but when i receive that list at client side, and see what it is in the received object at run time, in Non Public Members i saw all the properties that are specific to type that inherits from Construction, like Rooms, Floor, but in Result View it shows all properties have the value "0", and not the value with which they were sent.
On data contract Construction, at the top of class, are KnownType attributes to inherited classes.
It maybe helpful to know, I use Web Service Software Factory.
Sorry for my bad English.
If you see that properties are populated in an object in your service just before it is sent over the wire to the client (i.e. just before serialization), and then see that the received object is missing the values in those properties just after it is received by the client, it means that they were lost in the serialization process.
There are 2 things you need to remember about serialization:
You need to make sure the classes you send over the wire are marked with the [DataContract] attribute, and that all properties within that are marked with the [DataMember] attribute. If a property is not a .NET type, then the class that defines (and the properties within it) it also needs to be marked up with these attributes.
Class Inheritance is lost in serialization. If you create an object of type "Building", and your WCF service method returns a type of "Construction", then the message sent to the client might not serialize correctly (eg. could it only be serializing the properties defined in the base type "Construction"?). I suggest you test this out by making your service return the inherited type rather than the base type, and see if it fixes the problem.
I think that the 2nd point is the most likely cause of your issues. If you provide your code I can help you in more detail
I have inherited an application that is logically split into 4 tiers, but physically resides across two. The 4 logical tiers are:
asp.net website
business logic in a C# .Net assembly (referenced from website)
data access c# assembly - classes generated by codesmith tool (referenced from business logic)
sql server database
An example of the way that the website interacts with the business layer is:
Booking b = new Booking();
b.property1 = x;
b.property2 = y;
result = b.method();
ie. it sets the data on public properties of the biz class then executes a method that in-turn reads from the properties.
Unfortunately, there are lots of properties and some of these are not base types, they are other objects eg the Booking object contains collection of Vouchers objects
I need to make the tiers 2-4 available to a new user interface (a very different website that will serve in-store kiosks).
I would like to expose the business layer through WCF. I have created an IBooking interface, defined the method signatures and decorted with [OperationContract] etc. Where I'm stuck is how to manage the data. I realise that I could define a data contract to match the various public properties of the Booking object but then I would need to make significant changes to the existing website - rather than it setting the properties and calling a method withouth parameters it would need to populate an instance of the data contract and pass this as a parameter to every method call.
Could anyone advise on the best way to approach this please. I am able to make changes to the exisiting website but I'd like to keep these to a minimum.
Many thanks,
Rob.
I'd suggest the simplest means of implementing this would be to create a WCF wrapper around your existing business logic without altering your current website. This can be done without any (significant) code changes to what you already have. The 'downside', if you consider it such, is that your existing website won't use your WCF services.
You've already created an contract for the service. If you haven't already, create message contracts for the operation parameters. Then you can create your 'new' website by working with the service contract & message contracts.
Services are different to OO, in that you don't normally set properties & then call parameterless methods - instead you invoke an operation and include any relevant, required data at the same time. Your service implementation - the class that implements the IBooking contract - will do the work of
instantiating your existing classes
populating those objects
calling the parameterless methods, and
returning results.
e.g.
// contract
[OperationContract]
MyResponseMessage DoMethod(MyResultRequest requestData);
// and the implementing class (the 'service')
public MyResponseMessage DoMethod(MyResultRequest requestData)
{
MyResponseMessage responseData = new MyResponseMessage();
Booking b = new Booking();
b.property1 = requestData.X;
b.property2 = requestData.y;
responseData = b.method();
}
I am trying to use Generic DataContract class so that I don't have to implement several types for a collection of different objects.
Exp :
I have a Profile object which contains a collection of objects.
So I want to have one Profile<Foo> and Profile<Foo1> where profile contains a collection of Foo or Foo1 objects.
I have been reading that WCF does not support generic classes and actually the error that I get is the following.
Type 'GL.RequestResponse.ProfileResponse1[T]' cannot be exported as a schema type because it is an open generic type. You can only export a generic type if all its generic parameter types are actual types.`
Now the ProfileResponse is this Profile object that I am trying to use.
Now in my host I am doing the following. :
ServiceConfig(typeof(ProfileHandler<EducationResponse>).Assembly,
typeof(ProfileRequest).Assembly,
typeof(Container)).Initialize();
This is dhe definition of the handler with the datacontract.
public class ProfileHandler<T> : RequestHandler<ProfileRequest,
ProfileResponse<T>>
The Container is using Windsor Container to register the objects.
The registration works fine but after I instantiated the Service Host for WCF processor, and call Open Method of the host I get the above error.
Is there really no way for me to write generic response requests for wcf with agatha ?
It feels like such a waste to have to define a Profile container class for each type being contained in that collection.
thanks.
One cannot have open generic handlers, because the server side needs to know what the type is.
One can use so called closed generic methods. This way the server side knows the types for witch to load the handler.
Also, one could potentially configure Agatha so that it allows to receive extra information related to the request. In this case, it would be the type wrapped in the response.
One could do this by defining a a BaseRequest class and having all the request extend this class. This class can have a property which takes the type of the response. Or the type to be wrapped in the response.
In the process, when examining the request, the process can get the type to be wrapped in the Response, so that i knows how to load the class.
I have not implemented this, since it would take too much time and I am not sure I want to be responsible for maintaining Agatha for our application, but this is how I would do it.