I am creating a WFC Restful service and there is a need to persist a variable that will be persist per user, is there a way I can achieve this without having to pass the variable to all my calls?
I am using trying to log the process of the user throughout the process, weather their request has failed or succeed, IP address, when they requested the action, failure time, etc.
Please note I am new to WCF, thanks in advance.
I recently worked on this (except it wasn't RESTFUL). You could transmit information through HTTP headers and extract that information on the service-side. See http://trycatch.me/adding-custom-message-headers-to-a-wcf-service-using-inspectors-behaviors/
For the client ID itself I can suggest two places to put it. One is OperationContext.Current.IncomingMessageProperties. Another is CorrelationManager.StartLogicalOperation which allows you to define a logical operation - that could be the service request, beginning to end - or multiple operations - and retrieve a unique ID for each operation.
I would lean toward the latter because it's part of System.Diagnostics and can prevent dependencies on System.ServiceModel. (The name CorrelationManager even describes what you're trying to do.)
In either case I would look at interception. That's the ideal way to read the value (wherever you store it) without having to pollute the individual methods with knowledge of logging and client IDs. (I saw from your message that you're trying to avoid that direct dependency on client IDs.)
Here's some documentation on adding Windsor to your WCF service. (At some point I'll add some end-to-end documentation on my blog.) Then, when you're using Windsor to instantiate your services, you can also use it to instantiate the dependencies and put interceptors around them that will perform your logging before or after those dependencies do their work. Within those interceptors you can access or modify that stack of logical operations.
I'm not doing Windsor justice by throwing out a few links. I'd like to flesh it out with some blog posts. But I recommend looking into it. It's beneficial for lots of reasons - interception just one. It helps with the way we compose services and dependencies.
Update - I added a blog post - how to add Windsor to a WCF service in five minutes.
Related
I think elements of this question have been answered elsewhere, but I couldn't find an answer to my specific circumstance.
I work with an enterprise application. This application interfaces with various 3rd party APIs & services via what is currently a single class and a plethora of proxy dlls. This means that each of these dlls is referenced in the main project. In addition to this, over time as we've added new service calls, a lot of code has been duplicated, with only very small amendments. Most of the service calls do roughly the same thing and take largely the same objects as parameters.
As you can imagine, this presents us with a number of problems, not least of which is the time it takes to add a new service.
We have a task now to refactor and streamline this process to make it more manageable and resilient - I have an idea in my head and I've done a lot of research but I just wanted to see if anyone had any better ideas or similar experiences before I dive in.
What I want to do is add a facade layer so that the base code gets all the data commonly used and bundles it off to the facade along with a parameter stipulating which service it wants to call. The facade would then pass the data to either the proxies or a bridge, which would transform it into the right format for the target service, make the required calls in order, and return any responses back to the facade to pass on.
Although I have an idea of the architecture I want, I'm not 100% sure which way to go in terms of concrete C# code - whether to add the facade and bridge/adapter code in a new project which also has the proxy dlls referenced, or whether to go down the base/interface route and add the required transformation classes directly into the proxy dlls.
Edited to add: I am unable to consider consolidating this functionality into a service or microservice due to wider infrastructure considerations that I am unable to discuss here.
Any suggestions appreciated!
I have a set of services I want to be able to access via one end point altogether.
Now I want to build something in wcf rather than use an existing framework/software so that is out of the question.
Suppose I have 10 contracts each representing a contract of an indepedent service that I want to "route" to, what direction should I go?
public partial class ServiceBus : ICardsService
{
//Proxy
CMSClient cards = new CMSClient();
public int methodExample()
{
return cards.methodExample();
}
So far I've tried using a partial class "ServiceBus" that implements each contract but then I have more than a few (60+) recurrences of identical function signatures so I think I should think in a different angle.
Anyone got an idea of what I should do? or what direction to research? currently I'm trying to use a normal wcf service that's going to be configured with a lot of client end points directing to each of the services it routes TO - and one endpoint for the 'application' to consume.
I'm rather new at wcf so anything that may seem too trivial to mention please do mention it anyway.
Thanks in advance.
I have a set of services I want to be able to access via one end point
altogether.
...
So far I've tried using a partial class "ServiceBus" that implements
each contract
It's questionable whether this kind of "service aggregation" pattern should be achieved by condensing multiple endpoints into an uber facade endpoint. Even when implemented well, this will still result in a brittle single failure point in your solution.
Suppose I have 10 contracts each representing a contract of an
indepedent service that I want to "route" to, what direction should I
go?
Stated broadly, your aim seems to be to decouple the caller and service so that the caller makes a call and based on the call context the call is routed the relevant services.
One approach would be to do this call mediation on the client side. This is an unusual approach but would involve creating a "service bus" assembly containing the capability to dynamically call a service at run-time, based on some kind of configurable metadata.
The client code would consume the assembly in-process, and at run-time call into the assembly, which would then make a call to the metadata store, retrieving the contract, binding, and address information for the relevant service, construct a WCF channel, and return it to the client. The client can then happily make calls against the channel and dispose it when finished.
An alternative is to do the call mediation remotely and luckily WCF does provide a routing service for this kind of thing. This allows you to achieve the service aggregation pattern you are proposing, but in a way which is fully configurable so your overall solution will be less brittle. You will still have a single failure point however, unless you load balance the router service.
I'm not sure about making it client side as I can't access some of the
applications (external apis) that are connecting to our service
Well, any solution you choose will likely involve some consumer rewrite - this is almost unavoidable.
I need to make it simple for the programmers using our api
This does not rule out a client side library approach. In fact in some ways this will make it really easy for the developers, all they will need to do is grab a nuget package, wire it up and start calling it. However I agree it's an unusual approach and would also generate a lot of work for you.
I want to implement the aggregation service with one endpoint for a
few contracts
Then you need to find a way to avoid having to implment multiple duplicate (or redundant) service operations in a single service implementation.
The simplest way would probably be to define a completely new service contract which exposes only those operations distinct to each of the services, and additionally a single instance of each of the redundant operations. Then you would need to have some internal routing logic to call the backing service operations depending on what the caller wanted to do. On second thoughts not so simple I think.
Do you have any examples of a distinct service operation and a redundant one?
I have a small website I implemented with AngularJS, C# and Entity Framework. The whole website is a Single Page Application and gets all of its data from one single C# web service.
My question deals with the interface that the C# web service should expose. For once, the service can provide the Entities in a RESTful way, providing them directly or as DTOs. The other approach would be that the web service returns an object for exactly one use case so that the AngularJS Controller only needs to invoke the web service once and can work with the responded model directly.
To clarify, please consider the following two snippets:
// The service returns DTOs, but has to be invoked multiple
// times from the AngularJS controller
public Order GetOrder(int orderId);
public List<Ticket> GetTickets(int orderId);
And
// The service returns the model directly
public OrderOverview GetOrderAndTickets(int orderId);
While the first example exposes a RESTful interface and works with the resource metaphor, it has the huge drawback of only returning parts of the data. The second example returns an object tailored to the needs of the MVC controller, but can most likely only be used in one MVC controller. Also, a lot of mapping needs to be done for common fields in the second scenario.
I found that I did both things from time to time in my webservice and want to get some feedback about it. I do not care too much for performance, altough multiple requests are of course problematic and once they slow down the application too much, they need refactoring. What is the best way to design the web service interface?
I would advise going with the REST approach, general purpose API design, rather than the single purpose remote procedure call (RPC) approach. While the RPC is going to be very quick at the beginning of your project, the number of end points usually become a liability when maintaining code. Now, if you are only ever going to have less than 20 types of server calls, I would say you can stick with this approach without getting bitten to badly. But if your project is going to live longer than a year, you'll probably end up with far more end points than 20.
With a rest based service, you can always add an optional parameter to describe child records said resource contains, and return them for the particular call.
There is nothing wrong with a RESTful service returning child entities or having an optional querystring param to toggle that behavior
public OrderOverview GetOrder(int orderId, bool? includeTickets);
When returning a ticket within an order, have each ticket contain a property referring to the URL endpoint of that particular ticket (/api/tickets/{id} or whatever) so the client can then work with the ticket independent of the order
In this specific case I would say it depends on how many tickets you have. Let's say you were to add pagination for the tickets, would you want to be getting the Order every time you get the next set of tickets?
You could always make multiple requests and resolve all the promises at once via $q.all().
The best practice is to wrap up HTTP calls in an Angular Service, that multiple angular controllers can reference.
With that, I don't think 2 calls to the server is going to be a huge detriment to you. And you won't have to alter the web service, or add any new angular services, when you want to add new views to your site.
Generally, API's should be written independently minded of what's consuming it. If you're pressed for time and you're sure you'll never need to consume it from some other client piece, you could write it specifically for your web app. But generally that's how it goes.
I'm working on a system right now that is in a single process space; we are breaking this up into several processes, initially to run on the same box but ultimately to distribute across several separate machines. I'm leaning towards using an ESB (NServiceBus, Rhino ESB) or possibly rolling my own with WCF + queues to handle the pub/sub and request/response scenarios our app has.
However, I'm struggling with the abstraction: I don't want the various components to know they are talking over the bus. The current APIs connecting the various services translate pretty well to this kind of model, but I want to hide that from the client and server sides. Short of writing a lot of custom proxy code for the client and server, is there a better way to approach this? I realize WCF can auto-generate proxies based on the service definition, but I really like some of the other stuff I get with (say) rhino servicebus.
Ideally, I'd like to be able to swap out different implementations (with and without an ESB/messaging layer) just using IoC (knowing there would have to be limits enforced by convention on what can be passed across the interfaces), but I'm not sure where to go with that. I'd really prefer to not have to change every method call on the current interfaces into its own discrete message class, either.
Any resources/patterns/tools to help me do this? Please ask questions if I'm not clear. Thanks.
There may not be one solution/off-the-shelf component that might help you.
Problem 1:
The basic problem can be solved via an ESB, as it provides location transparency and service aggregation. A regular ESB mediates/brokers requests between service consumer and service provider.
Take a simple example:
Service_A depends on Service_B
Service_C depends on Service_B
Service_B depends on Service_D
In this scenario, the best way to progress is this:
Define contracts exposed by Service_B and Service_D as external dependencies (possibly as a web service, though an ESB supports multiple protocols) in services Service_A, Service_C and Service_B, and consume via an ESB.
In ESB, to start with, route thes services Service_B and Service_D on the same instance.
If you migrate Service_D and Service_B as Service_Dx and Service_Bx on a different location, the ESB can be reconfigured to route to the new location. Also, an ESB can be configured to route to Service_B or Service_Bx based on some set of parameters (eg., test data to Service_B and production data to Service_Bx)
Problem 2:
The problem of IOC could probably be hard to achieve; there may not be a need.
I presume the clients, instead of consuming from a known location, are injected with the whereabouts of service location. This in reality transfers the configuration to client side. With this, for every new client added to the system there needs to be a separate configuration control. This might lead to logistical issues.
Please post your final solution, very interested to know your approach.
A project I am working on requires a structure as such:
{BasePrefix}/Application/{id}/Security/Users/{userId}
{BasePrefix}/Application/{id}/Objects/{objectId}
etc.
Application.svc would be end up being my WCF Web Service. I tried to convince them to do:
{BasePrefix}/Security/Application/{id}/Users/{userId}
This would allow me to have multiple WCF Web Services as Security.svc, Objects.svc, etc.
They still want it all under application so instead of throwing all my service methods into a single file, I wanted to break it out by functionality and use partial classes to combine it all into one resource.
I saw an article about how to do this here: http://www.meineck.net/2008/04/wcf-hosting-multiple-wcf-services-as.html
The developer in that article is working with a Net TCP binding, however, so I am not sure if this will work with a WebHttpBinding and how IIS will handle the multiple resources.
Has anyone done this? Is the article I linked a good resource? Or is there a better alternative method to achieve the same results?
The methodology in the linked article is sound, and will work for bindings other than netTcpBinding (including webHttpBinding, wsHttpBinding and so on).
However, I believe what you are trying to do is use a URL rewriting scheme (probably using the UriTemplate property), which is subtly different from what that article actually talks about. It is referring to the creation and implementation of multiple interfaces, by the same service, and mapping each interface to its own endpoint.
The approach does not work with a single endpoint. So if your endpoint is {BasePrefix}/Application, that can only be mapped to one interface (say IApplicationService) in the configuration.
In your case, I don't think you'll be able to go the multiple-interface route because you need to have just one endpoint. So you'll still need a single monolithic interface with all of the methods (ugly), but you could in theory use partial classes to split up the implementation of those methods into logical groups. It's better, but not exactly ideal.
You were on the right track with your original assessment. If your scheme looked like:
{BasePrefix}/Security/Application/{id}/Users/{userId}
{BasePrefix}/Repository/Application/{id}/Objects/{objectId}
Then you would be able to use either of the approaches - either have multiple services, or have a single service that implements multiple interfaces and hosts multiple endpoints.
What the code/configuration in that article is really designed to do is enable a single service instance to host multiple endpoints. The main reason to do this is if you would otherwise have to duplicate a lot of code between services. Unfortunately that's not your goal here, so you will either have to push harder for your proposed URI scheme, or deal with a monolithic service contract (interface) and do the best you can to keep the implementation clean through #region directives and/or partial classes.