I am learning WCF,one of the benefits of WCF is that you can use WCF even the client and service are not in the same network.Can anyone explain why?
Why using normal asp.net services, .NET remoting or Windows enterprise service client and service have to be in the same network?
Another question is that does the client needs to have a service contract interface and data contract? I assume not ,but how the client understand the type returned from the WCF services?
Edit: Reflecting More comments
A primer on WCF (such as What Is Windows Communication Foundation?) is a good place to start. WCF can use SOAP to implement the contracts way down deep. WCF also uses a variety of communication facilities within windows (and any custom ones you want to create) so talking across machines is built in.
The very essence of contract (IMO) implies that this is present on both sides of the communication. In a pure .net cases I've usually put the contract definitions in separate assemblies and share them. In other places I've used WSDL to be the main contract definition so that the client and service share definitions.
Edit: Answering comments
You can knock up simple examples of communication in WCF easilyy (provided you know the basics of comms on windows including firewalls etc). However doing something custom is not easy but there are many many resources on the web and books to help you get there.
The books i used:
http://www.amazon.com/Programming-WCF-Services-Juval-Lowy/dp/0596526997
http://www.amazon.com/Essential-Windows-Communication-Foundation-WCF/dp/0321440064/ref=pd_bxgy_b_img_c
http://www.amazon.com/Inside-Windows-Communication-Foundation-Developer/dp/0735623066/ref=sr_1_1?ie=UTF8&s=books&qid=1252111759&sr=1-1
Another question on SO with a set of resources is "WCF for the Totally Clueless"
I don't know where you read that a benefit of WCF is that it allows the client and server to be on different networks. They can already be on different networks using .NET Remoting or DCOM (Enterprise Services).
The client does need to know the service contract and any other contracts required in order to use the service. This can be provided through WSDL or the Metadata Exchange Protocol (mex). If using .NET on both sides, then it is possible to share the contract assemblies, but this introduces a coupling between client and service.
Previous Microsoft technologies were designed for some specific needs in particular environment. For example ASMX Web Services were designed to send and receive messages using SOAP over Http only. .NET Remoting specific to Microsoft environment, no interoperability. But WCF is designed to send and receive messages using any format (SOAP as default) over any transport protocol i.e. HTTP, TCP, NamedPipes, MSMQ etc.
And your second question "but how the client understand the type returned from the WCF services?"
Its through proxy, client interacts with proxy which contains all the types etc.
You can find a good concepts and questions here for understanding WCF core concepts.
Related
I am relatively new to WCF. I am developing Web application.
I am trying to understanding "Why WCF" and read many articles .
But in many places it has been mentioned "to developed service oriented architecture ,to asynchronously send data" without any detailed explanation / any basic example.
Can somebody please let me know one simple example in layman's term ,"Why WCF" so that I can appreciate its existence.
I have had conversations with many people but none of them were able to answer this basic question.
I am also aware that ,many hundreds of applications have gone live before WCF was there...
Suppose, you do have a task to make a procedure of recieving of the coordinate point (lat,lon) and and returning the picture of the surrounding area. Or to make a language translator from voise input to text output. These jobs could uses several servers with a lot of data and could makes some huge mathimatic calculations. But you procedure should me quick, platform independend, secured, protocol-independent, consumed by different technologies (Web, Mobile, Applications). And at the same time it should be easy to consume by the end users, which do know nothing about you. As the main aim of ASP to handle web requests and generate the html responses, so the aim of WCF is to supply the end user with some useful functionality, developed by another user, remotly.
The developer creates a service (WCF) where he specifies its adress, binding and contract. Knowing these parameters other developers can consume this service. They can consume it by ASP, SilverLight, WPF, WinForms or any other technology (even none-microsoft), using SOAP protocol.
From Wikipedia:
The Windows Communication Foundation (or WCF) is an application
programming interface (API) in the .NET Framework for building
connected, service-oriented applications.
WCF is meant for designing and deploying distributed applications
under service-oriented architecture (SOA) implementation. **
Architechture
** WCF is designed using service oriented architecture principles to support distributed computing where services have remote consumers.
Clients can consume multiple services; services can be consumed by
multiple clients. Services are loosely coupled to each other. Services
typically have a WSDL interface (Web Services Description Language)
that any WCF client can use to consume the service, regardless of
which platform the service is hosted on. WCF implements many advanced
Web services (WS) standards such as WS-Addressing,
WS-ReliableMessaging and WS-Security. With the release of .NET
Framework 4.0, WCF also provides RSS Syndication Services,
WS-Discovery, routing and better support for REST services. Endpoint A
WCF client connects to a WCF service via an Endpoint. Each service
exposes its contract via one or more endpoints. An endpoint has an
address (which is a URL specifying where the endpoint can be accessed)
and binding properties that specify how the data will be transferred.
http://en.wikipedia.org/wiki/Windows_Communication_Foundation
Useful resources:
http://msdn.microsoft.com/sv-se/library/dd943056%28en-us%29.aspx
http://www.wcftutorial.net/
http://blah.winsmarts.com/2008-4-Writing_the_WCF_Hello_World_App.aspx
http://blah.winsmarts.com/2008-4-Writing_your_first_WCF_client.aspx
I am starting a new webservice project which will be consumed by multiple consumer applications done in different technology like ASP, ASP.Net and PHP. I am planning to develop this service as a WCF service. I am new to WCF and I understand WCF is like umbrella tech which has all the features for developing a distributed SOA applications.
I would like to get your advice on whether my choice of opting WCF service over classic asmx service is correct. The consumer applications are existing application done different technologies as I said before. This service is a simple service that creates and updates user information in a centralized DB.
If my decision of choosing WCF is correct, then please let me know if there are any specific things I need to consider so that the existing application can consume my WCF service without any hiccups. In other words, I can provide a asmx service for this which they can consume directly without any issues (and currently they are consuming some of our asmx service. Since the current requirement is new I want it to be done with WCF). Likewise, the consumer should be able to consume my service like they consume asmx service.
I am asking this question because WCF provides additional features like security, etc. and hence the consumers should also follow the practice to communicate with the service.
Any advice is highly appreciated.
You probably want to use BasicHttpBinding in your WCF service and, although I'm not a PHP developer, I understand that PHP 5 has a SOAP library that can be used to create a service proxy based on the WSDL document exposed by the WCF service, assuming metadata exchange is enabled.
I am new to .net and am trying to use c# as the basis of my .net learning. I have a project where I need a service to connect to mutliple tcpip applications that are a 3rd party application written in vb6. Someone has mentioned using WCF as the base, but i'm not sure how it would make an outbound connection (instead of receiving incoming ones) to a non .net application? Please help
With C# and WCF, you can either create:
a WCF service which will offer up some functionality that other applications can call
or:
a client that connects to some other SOAP or REST service to consume functionality.
So which one is it you're looking for??
Also: WCF is a SOAP or REST based service stack - you cannot use it to connect to low-level TCP calls (socket programming). Your "other" side must understand either SOAP (the web service protocol) or REST (the URL-based lightweight protocol). If you other sides don't speak neither SOAP nor REST, you're out of luck and can't really use WCF for that.
You'll have to deal with socket programming, WCF won't help you here.
Try reading this: http://www.codeproject.com/KB/IP/socketsincsharp.aspx
I use the term network services to refer to things such as NNTP, IMAP, POP3... things which have a defined protocol layered on top of TCP/IP.
I'm having a very difficult time figuring out how I can connect to an existing network service using a WCF client. I haven't found any examples other than ones that are basically using C#-ified socket code.
Can anyone refer me to any examples of using WCF to talk to a legacy service as something other than a glorified socket?
Is WCF even appropriate for this type of requirement?
Thanks.
WCF comes with a set of standard bindings, here is a list of the bindings provided in 3.5:
http://msdn.microsoft.com/en-us/library/ms730879.aspx
If you need to use anything else, WCF is probably not the way to go. Even if you could build your own binding, the cost would outweigh the benefit.
If you have a requirement in your project that everything should use WCF, you could build a WCF facade over your sockets code.
Well, the term "WCF" actually means 2 things:
The framework: "ABC" - Address, binding, contract
Actual use of a combination of the above (for example, a WCF webservice using BasicHttpBinding)
There's not built in bindings for the protocols you mentioned, which is why the examples you'll see looks like "glorified sockets" - That's what they are. That's what a binding is: A level of abstraction built on a basic protocol (typically UDP/IP or TCP/IP).
Now, with all this being said, you need to build / borrow / steal / whatever a binding that is usable with your protocol of choice. This might look like you're just injecting sockets into the WCF framework, and honestly, that's just what it is :)... So what's so great about it?
If you managed to implement your binding to-the-specs, you got yourself a very easily substituted component, which will fit into all WCF applications. Whether you want this behaviour or not, is up to you and your requirements :)
Good luck with it.
Well, WCF at its heart is the unified communication engine offering by Microsoft, based on SOAP - it replaces ASMX web services, WSE, .NET Remoting and more.
As such, it's SOAP based and therefore can talk to anything that talks SOAP - which I doubt is the case for POP3 or other services. So I don't think you can write a WCF client for these services, really.
As for writing these services from scratch and exposing them as WCF services - that might work, since basically the WCF service implementation can do anything, and then present itself to the outside world as a SOAP service - could work, question is: what's the benefit?
Marc
I am learning wcf but I have trouble understanding the benefits. Is there ever a time I would want to use traditional web services?
I read another thread with these benefits:
Opt in model for members using a certain attribute
Better security
No need to worry about binding (can't understand how this is true)
No need to worry about the xml
I read Programming WCF Services however this was an advanced book a bit like CLR via C#. I am now reading Learning WCF Services and will read Essential WCF (is recommended).
What would happen if I use a normal class to try to talk to a web/service reference? I know this sounds really naive, it's just my lack of experience in web services.
I am coding some WCF services so I am getting exposed to the specifics. They are interacting with a SOAP web service provided by my web host so I can get stats on my site. Is there anything wrong in this approach?
Thanks
WCF is a unified programming model for developing connected systems. What this means is that you use a single framework to develop service-oriented solutions. WCF allows you to keep your service implementation relatively unaware and care free of what's going on under the covers as far as how your service is consumed by clients and communication is handled. This allows you to take your service implementation and expose it in various ways by configuring it differently without touching your service implementation. This is the unified part. Without WCF, you have to get familiar with a framework specific for a particular communication technology such as ASP.NET asmx web service, .NET remoting, MSMQ etc and usually those frameworks impose on your service implementation and creep in such as using WebMethod attribute or having to derive from MarshallByRefObject object etc and you just can not take your service implementation and easily expose it over another communication stack. If I have a service that adds two numbers, why can it not be exposed over http or tcp easily without having to worry about low level details? This is the question in your post regarding binding. Binding allows you take a service and configure it so that it can be exposed over different transports and protocols using different encodings without ever touching your service implementation.
Is there ever a time I would want to use traditional web service?
Web service uses well defined, accepted, and used standards such as HTTP and SOAP. So if you want your service to be consumed by wide range of clients, then you would want to expose your service as a web service. WCF comes with pre-configured bindings out of the box that allows your service to be exposed as a web service easily: basicHttpBinding and wsHttpBinding. You may also want to consider RESTful services which is an architectural style that fits more natural with the HTTP model. WCF supports RESTful services as well
What would happen if I use a normal
class to try to talk to a web/service
reference? I know this sounds really
naive, it's just my lack of experience
in web services.
WCF service can expose the wsdl for a service just like ASP.NET asmx web service does. You can generate a client side proxy by simply adding a service reference to your client project. There is also a command line tool called svcutil that also generates the client side code that allows you to easily communicate with the service. The client side service class basically mirrors the service interface. You create an instance of the client side proxy for the service and then simply call methods on it just like any other .NET object. Under the covers, your method call will get converted to a message and sent over the wire to the server. On the server side, that message will get dispatched to the appropriate service method.
I hope this helps a bit.There are lots of online content such as videos on MSDN and channel 9 that you check out. The more you pound on it and expose yourself to it, the clearer WCF will get I am sure. Also, WCF is THE framework Microsoft recommends to develop connected system in .NET. The other technologies ASP.NET asmx, WSE, and .NET Remoting will most likely still be available going forward but may not be supported and developed further.
There are a number of existing approaches to building distributed applications. These include Web services, .NET Remoting, Message Queuing and COM Services. Windows Communication Foundation unifies these into a single framework for building and consuming services.
Here is a link from MSDN Why Use Windows Communication Foundation?
WCF is really the "new" standard and new generation of web service - and even more generally, communications - protocols and libraries for the .NET world.
Whenever you feel the need to have two systems talk to one another - think WCF. Whether that'll be behind the corporate firewall in your company LAN, whether it's across the internet, by means of a direct call or a delayed message queueing system - WCF is your answer. Mehmet has written a really nice summary of how WCF is the unification of a great many communication standards that existed in the Microsoft world before WCF.
I would think with the "Learning WCF" book, you should be a lot better off than with Programming WCF - that's quite advanced stuff already!
One of the mainstays of WCF is the architecture that you always talk to your service through a proxy - whether that service runs on the same machine using NetNamedPipe binding or halfway around the world in Down Under on a server - no difference, you always go through a proxy. That then also allows WCF to be so extensible - thanks to the proxy always being between the client (your application) and the service, it offers excellent ways of extending the behavior and the inner workings of WCF to your liking and needs.
WCF basically builds on SOAP communications - so interfacing and using existing SOAP services should be no problem at all. With the WCF REST Starter Kit and in the upcoming .NET 4.0 release cycle, WCF will also extend its reach into the REST style web communications, if that's ever going to be a requirement of yours.
All this really shows one of the biggest strenghts of WCF: it's a unified and extremely flexible and extensible communication framework, that can handle just about anything you throw at it. That alone is more than enough reason to learn WCF (which can be dauting at first, I agree!), and you won't regret the effort you put into this endeavor.
Marc
Have you a specific application you are writing for, or just getting your feet wet?
Google protocol buffers, is a very good choice of communications. John Skeet & Marc Gravell have both done C# implementations. See here