is it possible to build a web services (let's call it A) that can communicate with one or more webservices?
kind of a SOAP proxy?
the webservice A will build it's functions based on other web service in server B and C
so clients will just send request to A and A will know here to send the request to (B or C)
is it possible to build such app?
It's definitely possible and it's not something that lives or is bound to SOAP Web Services as this is an application implementation concern. What you should be more concerned with is how you are going to go about doing it.
Using Data Transfer Objects
Having spent many years developing Web Services I believe the best approach in the design of your web services is to follow Martin Fowler's DTO pattern where you communicate using remote-service-specific DTO's using a client proxy (aka Service Gateway) to the Web Service (aka Service Interface). This 'message style' of web services is great from a Performance, SOA, re-usability point of view. Which forms the foundation of how my ServiceStack web services framework was built.
The WCF RPC Approach
Unfortunately this best-practices convention is effectively discouraged by Microsoft's WCF SOAP Web Services framework as they encourage you to develop API-specific RPC method calls by insisting you to use method signatures to define your web services. You can of course still develop 'message based' apis however it requires more effort to do so and is rarely demonstrated in their online tutorials. In my opinion this results in a client-specific API which encourages more remote method calls which as a result are less performant. At times I really wish Microsoft would follow well established practices as published by industry experts instead of their often primary motivation of catering for drag-n-drop developers.
Calling multiple Web Services Asynchronously
Going back to your original question you would define a web service that takes a request and if you're lucky that all your proxy web services share the same interface you should be able to use the same client proxy in a loop by changing the url for each service endpoint. I generally recommend that you fire each request off asynchronously (and join at the end) to speed up the execution time of your 'master web service'.
Don't know if I understand your question the way it was meant, but it's possible to add a service reference to your webservice.
Which webservice to send the request to, you probably have to code ;-)
If I understand correctly, you have 3 components in your app :
The client App
A "frontend" web service "WS A"
two other "backend" web services, "WS B" and "WS C"
by frontend, I mean the web service is the only one exposed to the client, in other words a "facade".
If this is correct, you can reference the "WS B" and "WS C" from the "WS A" project. The code in the "WS A" can act as a client to these web services. This is often called an SOA architecture (service oriented architecture), where each service provides a functionnality, and can communicate with each others.
Thinks starts to be a bit difficult when you have infrastructures requirements (like delegating the client credentials), but I think it's the cleanest way to achieve what you want.
Related
I know that ASP.net web service supports only HTTP protocol and with WCF you have more options like TCP and Named pipes etc. Can you think of any scenarios in which one might have to consume a WCF service through an ASP.net Web API?
Following would be one of them use case where you want to call wcf service from web API.
If you already have a wcf service running and available which is doing some complex operations and you do not want it to be available directly to your consumers, you can create a web API and call the wcf service to perform the complex tasks and let the consumers to use the web API. In web API you can put extra logic of validation and authorization of the incoming requests.
Wcf being an older technology it would be better to write something new and eventually replace wcf rather than maintaining it.
Also If the current wcf is setup is not available via http protocol then not all the clients can communicate with it. Web API has that edge over wcf service.
How web API would connect to wcf service?
This depends on lot of factors such as network, deployment strategy, security etc.
But following would be one of the examples.
If the wcf service is available on tcp and web API and wcf are running on the same network, then web API can call wcf.
There may be a different answer to this question based on what exact problem you are trying to solve.
My answer is based on what information you have provided and the experience I gained by solving similar issue in real life.
I have read many articles in the web so far, about the differences between WCF and ASP.Net web API. Unfortunately I could not come up to a clear idea about what will serve my purpose. Most of the Articles I have read highlighted on the design point of view of the two web services. But I am confused what will work best for my project and why? Here is my brief description of the project.
I need to create a communication channel between two servers (both are written in C#). The servers will communicate using messages (certain type of commands). The messages sometimes can be only acknowledgements, and sometimes the messages may contain instructions to do some computation. For example, one message can be draw something, or send an SMS etc. And not necessarily the messages will involve any database transactions. But the messages can sometimes send large text files as payload (around 1-5 MB maxm). What I believe WCF is very will surely do this, but can I do the same with ASP.net web API. Because so far all the example I have seen for ASP.Net web api: they are good for RESTful services that manipulate some kind of DB store (GET, PUT, DELETE). But in my case I will need to expose service points that will
do some kind of processing such as return the value of a computation, sending and acknowledging messages, etc.
Not just manipulating a DB-store.
So, what should be the best and simplest way to do so? It is needed to be mentioned that I did not find any straight forward example of achieving this using ASP.Net web API.
The Question you have asked is an overly-broad or primarily opinion-based, and its hard to give an example for what you have asked.
Important Points:
Firstly, if you are going to create a service which would be used on different platforms, then go with WCF.
Secondly, if you are creating internet service which is going to use external resource, then go with Web API.
Web API is the best choice if you are going to create a service for low bandwidth devices or mobile devices to access client.HTTP
request/response is also more readable as compared to SOAP because it
contains header, body, etc. which makes it complex.
Just take few minutes and read the below article, until you get complete understanding of few principles.
Original Source Can be found Here, Here and Here.
To whom choose between WCF or WEB API :
Choose WCF when you want to create a service that should support special scenarios such as one way messaging, message queues, duplex communication etc.
Choose WCF when you want to create a service that can use fast transport channels when available, such as TCP, Named Pipes, or maybe even UDP (in WCF 4.5), and you also want to support HTTP when all other transport channels are unavailable.
Choose Web API when you want to create a resource-oriented services over HTTP that can use the full features of HTTP (like URIs, request/response headers, caching, versioning, various content formats).
Choose Web API when you want to expose your service to a broad range of clients including browsers, mobiles, iphone and tablets.
Why to choose Web API
Web API doesn't have tedious and extensive configuration like WCF REST service.
It is very simple, creating service with Web API. Where as With WCF REST, service creation is bit difficult (requires clear understanding of configurations).
Web API is only based on HTTP and HTTPS and easy to define, expose and consume in a REST-full way.
Web API is light weight architecture and good for devices which have limited bandwidth like smart phones.
My Opinion:
Simplest way to do so - Web API (Since you dont have any examples for this)
Hardest Way is (Configurations) - WCF (Better go with WCF, since you have examples)
I hope this gives you a clear idea about what to choose...
First things first, RESTful is a stateless and uniform interface norm that can be applied to web services. It doesn't have to be automatically and only plain old CRUD service backed by a DB.
In the real world, we can hardly say that all web REST API respect fully the norm, in fact they don't most of the time, especially the stateless part.
For your message based API, especially if it's bidirectional and event based, you can use websockets and consider the REST API a way to expose an uniform, stateless web interface to create those. And yes you can use websockets with ASP.NET WebApi there's plenty of tutorial out there, even for the newer ASP.NET Core.
The "between services" interactions part is no different than the usual Web browser <=> Web service, you're just using C# code instead of JS for the client.
I can hardly recommend WCF that uses SOAP since it's hardly portable considering the web standards nowadays. For instance if want to use a browser client instead of another ASP.NET service, well you'll have to do additional code client side to handle supports.
You can use WCF websockets, providing the almost all the advantages of WCF SOAP.
tl;dr :
You can mix RESTful and Websockets, it can actually be better than going full REST or full Websockets
It's personal preference to use SOAP over websockets but do comes with a potential technical debt considering what you want to do afterwards
Message API between services is no different than a message API between a service and a browser
WebAPI is not just good for RESTful webservices. You can easily send requests to a WebAPI controller and handle it the way you want : calculations, sending messages, interact with a CRM, interact with DB or anything else.
WCF was created to manage SOAP based webservices and brings extra complexity. It handles TCP, Mime...
If you just need to handle HTTP requests, the simplest way is to go with WebAPI.
I would suggest Web API if it is for RESTful services as WCF was never made to serve as Restful services although you can serve as one where as Web API was made particularly for this.
I'm looking at converting an existing web service into a Web API. I've only worked with a WS a little bit and it was a long time ago. What I do remember is that in my project I would make reference to a service location and then use that reference to call whatever method I needed.
EX: I would reference http://mydomain/webservicename/mobile.asmx and then would call objWS.MethodName() what was coded within the mobile.asmx file.
If I convert over to using a Web API I would basically call the HTTP by going to something like http://mydomain/controllername/myMethod.
As of right now I don't have access to the client code to be able to change the way that it calls the service. That being said am I stuck with using a traditional web service vs web api?
This is an app on a handheld scanner that I believe is running Windows CE. We are having some connectivity issues/database deadlocks and I was asked to look at it and see if I can help out. The current WS code is overly complicated IMO since it's only doing either an insert or an update to a database. I would also think that going with a Web API would make it a faster app since it's depending on cellular access for it's communication. JSON should be a smaller payload than XML.
So, I would like to just re-write it using Web API 2 and Entity Framework. However, I'm afraid I'm stuck to using WS since I don't have access to the client code.
Any suggestions?
It's a fairly broad architectural suggestion, but what you're proposing certainly sounds possible and even quite reasonable.
If I understand correctly, you currently have this:
Client -> ASMX Service
And you can't change the Client, only the ASMX Service. The first thing you're going to want to do this ensure that server-side business logic is de-coupled from the platform technology:
Client -> ASMX Service -> Business Logic
The idea here is that any application host should be able to reasonably invoke the same business logic, even if that logic is nothing more than direct database access. The application host itself should be little more than a pass-through set of operations to be invoked.
At that point, you can create a second application host alongside the first one:
Client -> ASMX Service ----|
|-> Business Logic
WebAPI Service --|
So now you have two different services which expose the same business logic, using two different web service technologies. Each of them should be very thin, as application host technologies should always be easily replaceable.
At this point, assuming there are no significant gaps in the operations available between the two services, you can publish the new service's specifications to clients and begin plans to deprecate the old service. When you can deprecate it is more of a contractual issue than a technical issue. However long you've committed to maintaining it, that's how long clients will have a reasonable expectation to still use it.
If you really want to, you can even have the ASMX Service be a pass-through to the WebAPI Service, but in my personal experience that adds unnecessary layering to the whole setup and artificially complicates the abstraction of the business logic. Either way, the interface exposed by the ASMX Service wouldn't change.
The main thing here is the logical abstraction of the operations being exposed and the analysis of any gaps between what the ASMX Service can do and what the WebAPI Service can do. If that gets complex, then that's an indication that the business logic (and indeed the whole solution domain) is tightly coupled to the application technology being used, namely ASMX web services. That is the problem to be solved. Once solved, creating different application hosts and exposing different services which invoke the same underlying business operations becomes almost trivial.
You are right; you are stuck if you can't change the client and you want to change service protocols. Your client currently has a specific .asmx endpoint it is configured to point to and until you can update that endpoint and have the client stop using the proxy generated from the service, you can't change to Web API.
I'd still rewrite the service to use EF, though.
I am working on a Visual Studio Application that references a WCF web service, and after some reading online I am pretty confused.
I have read that WCF is a framework for building a web service, but it is not an API. Is this true?
I was under the impression that Web Services are APIs; I always thought that APIs were Software as a Service (SaaS). Doesn't that mean that APIs and Web Services are pretty much the same thing? Or do I have the wrong idea?
Could this be a misconception of my understandings of SOAP and REST?
Basically I want to know whether a WCF built web service counts as an API, and why/why not?
WCF is an API that can be used to create APIS within your application.
Web Services usually involves creating an API within your application. There are valid APIs that are not Web Services, like the Win32 API.
Its possible to build a WCF web service with one web method for an application that would not be considered an API specifically since it does not contain a set of routines, protocols, or tools for building applications.
Review http://en.wikipedia.org/wiki/Application_programming_interface for what an API is.
According to wikipedia, yes, yes it is:
APIs often come in the form of a library that includes specifications
for routines, data structures, object classes, and variables. In other
cases, notably SOAP and REST services, an API is simply a
specification of remote calls exposed to the API consumers.
An API (Application Program Interface) is a way to interact with components of a system. It defines the operations that can be used to get data out or push it in.
WCF (Windows Communication Foundation) itself is a framework for building web services and other applications that need a communication channel to share data with other services/applications, it is actually a lot larger on what it can do. You can read more about it on MSDN. It is an API as it gives you objects that allow you to tell it interact with its' components.
REST and SOAP are just architecture styles that can be used to serve data via a service, it is defining how you should interact with the data rather than the components themselves.
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I've spent a few months trying to grasp the concepts behind WCF and recently I've developed my first WCF service application.
I've struggled quite a bit to understand all the settings in the config file.
I am not convinced about the environment but it seems that you can do amazing stuff with it.
The other day I've found out that Microsoft has come out with a new thing called ASP.NET Web API.
For what I can read it's a RESTful framework, very easy to use and implement.
Now, I am trying to figure out what are the main differences between the 2 frameworks and if I should try and convert my old WCF service application with the new API.
Could someone, please, help me to understand the differences and usage of each?
For us, WCF is used for SOAP and Web API for REST. I wish Web API supported SOAP too. We are not using advanced features of WCF. Here is comparison from MSDN:
The new ASP.NET Web API is a continuation of the previous WCF Web API project (although some of the concepts have changed).
WCF was originally created to enable SOAP-based services. For simpler RESTful or RPCish services (think clients like jQuery) ASP.NET Web API should be good choice.
ASP.net Web API is all about HTTP and REST based GET,POST,PUT,DELETE with well know ASP.net MVC style of programming and JSON returnable; web API is for all the light weight process and pure HTTP based components. For one to go ahead with WCF even for simple or simplest single web service it will bring all the extra baggage. For light weight simple service for ajax or dynamic calls always WebApi just solves the need. This neatly complements or helps in parallel to the ASP.net MVC.
Check out the podcast : Hanselminutes Podcast 264 - This is not your father's WCF - All about the WebAPI with Glenn Block by Scott Hanselman for more information.
In the scenarios listed below you should go for WCF:
If you need to send data on protocols like TCP, MSMQ or MIME
If the consuming client just knows how to consume SOAP messages
WEB API is a framework for developing RESTful/HTTP services.
There are so many clients that do not understand SOAP like Browsers, HTML5, in those cases WEB APIs are a good choice.
HTTP services header specifies how to secure service, how to cache the information, type of the message body and HTTP body can specify any type of content like HTML not just XML as SOAP services.
Since using both till now, I have found many differences between WCF and Web API. Both technology stacks are suited well to different scenarios, so it is not possible to say which is better, this depends on configuration and scenario.
Properties ASP.Net Web API WCF
--------------------------------------------------------------------------------------------------
End point (mainly) Http based SOAP based
Service Type Front End Back-end
Support caching, compression, versioning No
Framework ASP.net WCF
Orientation Resource Oriented Service Oriented
Transports http http, tcp, MSMQ, Named pipe
Message pattern Request reply request Reply, one way, duplex
Configuration overhead Less Much
Security lesser than WCF (web standard security) Very high (WS-I standard)
Hosting IIS IIS, Windows Service, Self hosting
Performance Fast A bit slower than Web API
In use from .NET 4.0 .NET 3.5
Note: The data is not only my view, it is also collected from other official websites.
WCF will give you so much of out the box, it's not even comparable to anything. Unless you want to do on your own implementation of (to name a few) authentication, authorization, encryption, queuing, throttling, reliable messaging, logging, sessions and so on. WCF is not [only] web services; WCF is a development platform for SOA.
Why I'm answering:
I took huge amount of time to understand the difference between these two technologies. I'll put all those points here that I think "If I had these points at the time when I was wondering around in search of this answer, then I have decided very earlier in selecting my required technology."
Source of Information:
Microsoft® Visual Studio® 2015 Unleashed
ISBN-13: 978-0-672-33736-9 ISBN-10: 0-672-33736-3
Why ASP.NET Web API and WCF:
Before comparing the technologies of ASP.NET Web API and WCF, it is important to understand there are actually two styles/standards for creating web services: REST (Representational State Transfer) and SOAP/WSDL. The SOAP/WSDL was the original standard on which web services were built. However, it was difficult to use and had bulky message formats (like XML) that degraded performance. REST-based services quickly became the alternative. They are easier to write because they leverage the basic constructs of HTTP (GET, POST, PUT, DELETE) and typically use smaller message formats (like JSON). As a result, REST-based HTTP services are now the standard for writing services that strictly target the Web.
Let's define purpose of ASP.NET Web API
ASP.NET Web API is Microsoft’s technology for developing REST-based HTTP web services. (It long ago replaced Microsoft’s ASMX, which was based on SOAP/WSDL.) The Web API makes it easy to write robust services based on HTTP protocols that all browsers and native devices understand. This enables you to create services to support your application and call them from other web applications, tablets, mobile phones, PCs, and gaming consoles. The majority of applications written today to leverage the ever present Web connection use HTTP services in some way.
Let's now define purpose of WCF:
Communicating across the Internet is not always the most efficient means. For example, if both the client and the service exist on the same technology (or even the same machine), they can often negotiate a more efficient means to communicate (such as TCP/IP). Service developers found themselves making the same choices they were trying to avoid. They now would have to choose between creating efficient internal services and being able to have the broad access found over the Internet. And, if they had to support both, they might have to create multiple versions of their service or at least separate proxies for accessing their service. This is the problem Microsoft solved with WCF.
With WCF, you can create your service without concern for boundaries. You can then let WCF worry about running your service in the most efficient way, depending on the calling client. To manage this task, WCF uses the concept of endpoints. Your service might have multiple endpoints (configured at design time or after deployment). Each endpoint indicates how the service might support a calling client: over the Web, via remoting, through Microsoft Message Queuing (MSMQ), and more. WCF enables you to focus on creating your service functionality. It worries about how to most efficiently speak with calling clients. In this way, a single WCF service can efficiently support many different client types.
Example of WCF:
Consider the example:
The customer data is shared among the applications. Each application might be written on a different platform, and it might exist in a different location. You can extract the customer interface into a WCF service that provides common access to shared customer data. This centralizes the data, reduces duplication, eliminates synchronization, and simplifies management. In addition, by using WCF, you can configure the service endpoints to work in the way that makes sense to the calling client. Figure shows the example from before with centralized access of customer data in a WCF service.
Conclusion:
i) When to choose Web API:
There is no denying that REST-based HTTP services like those created using ASP.NET Web API have become the standard for building web services. These services offer an easy, straightforward approach for web developers building services. Web developers understand HTTP GET and POST and thus adapt well to these types of services. Therefore, if you are writing services strictly targeted to HTTP, ASP.NET Web API is the logical choice.
ii) When to choose WCF:
The WCF technology is useful when you need to support multiple service endpoints based on different protocols and message formats. Products like Microsoft BizTalk leverage WCF for creating robust services that can be used over the Web as well via different machine-to-machine configurations.If, however, you do need to write an application that communicates over TCP/IP when connected to the local network and works over HTTP when outside the network, WCF is your answer.
Be Warned:
Web developers often view WCF as more difficult and complex to develop against. Therefore, if you do not foresee the need for multiprotocol services, you would likely stick with ASP.NET Web API.
There is a comparison on MSDN about this
WCF and ASP.NET Web API
For me, the choice was about Who the clients are, and where are they located?
Within the company Network and .NET based clients : Use WCF with TCP binding (Fast communication than HTTP)
Outside the company Network, and use diverse technologies like PHP, Python etc: Use Web API with REST
Business speaking, WebApi lacks of a WSDL, so the developers should document all manually. And if, for example, the WebApi operation returns a list of objects then, the client should creates the objects manually, i.e. WebAPI is really prone to errors of definitions.
The pro of Webapi is its more lightweight than WCF.
Regarding the statement "WebApi lacks of WSDL" there are several ways to generate Rest client. One popular approach is Swagger UI / (Swashbukkle Nuget). This gives a rich interface to understand the REST end point's input and output schema and online tool to test the end points.
JSON LD (Json Linked Documents) is another emerging standard which will further improve the JSON based REST developer experience by exposing the JSON schema with better semantics.
With wcf we can configure and expose the same service support for multiple endpoints like tcp, http.if you want your service to be only http based then it will be better to go with web API. Web API has very less configuration when compared to wcf and is bit faster than wcf. Wcf also supports restful services. If you have limitation of .Net framework 3.5 then your option is wcf.