Develop Reference

Custom Business Object : AJAX Enabled WCF

Can I pass a custom object between AJAX enabled WCF and my asp.net page?
I searched the web but could not find any examples. Most shows simple types like string and integers.
I also do not know how to populate custom object's property through JavaScript on the client side.
We have a browser add on and we have to pass data to that addon from a web service, I researched and looks like AJAX enabled WCF is way to go
Using .net framework 3.5 and VS 2008

You can't pass the actual custom objects, but you can of course pass the serialized version of them through your service and to your page, javascript, etc. Basically, you have to map the fields of your complex custom .NET types to classes decorated with the DataContract attribute. These classes are the types that your service will return. The DataContract-decorated classes will contain fields with primitive types, like strings, integers, etc. The WCF service will serialize these into XML or JSON.
On the client side, jQuery will be your best friend. I personally prefer JSON because the properties of your objects are much easier to get at that way instead having to deal with parsing a bunch of XML. So, setup your service to output JSON.
Also, to make your service URLs easier to read, make sure to use a RESTful approach. It's as easy as decorating your service methods with the WebGet attribute and supplying a UriTemplate. Once you see some examples, it'll blow your mind. Note: if you ever encounter a WebInvoke with Method="GET", just use WebGet instead...it's more compact...no Method specification needed.
This particular article was EXTREMELY useful to me when I was developing my WCF service and the ASP.NET app that consumed it: http://www.c-sharpcorner.com/UploadFile/sridhar_subra/116/
Here's another person asking the same question as you: http://social.msdn.microsoft.com/forums/en-US/wcf/thread/879d46af-9c78-4b5d-b746-82843d742a6f
Hope this helps! Long live WCF!

With .NET 3.5 your best bet is WebHttpBinding which accepts plain old XML (POX) and you need to send XML to the WCF service.
You can also use WCF REST using REST starter kit. For samples have a look here. This supports JSON as well.
If you were using .NET 4.0, JSON-enabled WCF HTTP was the way to go. WCF REST with 4.0 was an alternative although I really do not like it.

Making an ASP.NET ASMX web service easily callable by ColdFusion web clients

I've written an ASP.NET webservice (.asmx style rather than WCF) and I have the main web methods working now in my prototype enviroment. Now I need to add several new parameters to one of the webmethods but, more significantly, I need to make my webservice as "consumable" (callable) as possible from a ColdFusion web application. I'm confused about how to best design parameter types for the webservice methods in light of usage by CF (or other client callers).
My prototype relies on my own ASP.NET web page which calls my webservice; here is how the proxy class for my service is called from the .aspx page:
BrokerASMXProxy.Svc.FileService brokerService = new BrokerASMXProxy.Svc.FileService();
recNumber = brokerService.UploadFile(binData, fileNameOnly, kvData);
Here is the signature of the webmethod:
[WebMethod]
public string UploadFile(byte[] incomingArray
, string FileName
, MetaData[] metaDataArray)
I'm a little concerned already about the byte array and the MetaData array (will ColdFusion have a problem calling this service with argument types like that?). I assume strings are not a problem but what are the best practices for designing webmethods (and their types) for use by ALL types of callers?
p.s. I also have a DownloadFile webmethod that has "out" parameters:
[WebMethod]
public bool DownloadFile(string recNumString, out byte[] docContents, out string returnFiletype)
..and I wonder similarly about ColdFusion's accomodation of these outputs. Thank you in advance.

If you're running ColdFusion 8, and happen to have that on the same physical server as your .NET code, you may be better off using .NET integration, where you can write a .NET class and intantiate it inside your CF code as if it were a CFC or a Java object.
Here's a good example (with tons more on the same blog) of writing a .NET class that's used in CFML code.
However, if your .NET and CF app servers are not on the same machine, you may have to go with a web service as you originally thought.
The great thing about web services is that they are language agnostic. It looks like you have a MetaData type or class defined, and you're expecting a collection of those to be sent as an input parameter. What that's going to ultimately translate to is some XML that represents that array, and each item in the array will be broken down to its core parts (strings, numbers, bools, etc)... In theory, it should just work, as long as you design your input XML accordingly.
It's been a while since I last created a .NET web service, but I'm sure there's a way to look at the expected XML structure (aka WSDL). Find that, and you've got your answer. Then you just need to create XML that fits that definition from your ColdFusion code and you're all set.

WCF: Individual methods or a generic ProcessMessage method accepting xml

My company is developing an application that receives data from another company via TCP sockets and xml messages. This is delivered to a single gateway application which then broadcasts it to multiple copies of the same internal application on various machines in our organisation.
WCF was chosen as the technology to handle the internal communications (internally bi-directional). The developers considered two methods.
Individual methods exposed by the
WCF service for each different
message received by the gateway
application. The gateway
application would parse the incoming
external message and call the
appropriate WCF service method. The
incoming XML would be translated
into DataContract DTO’s and supplied
as argument to the appropriate WCF
method.
The internal application
exposed a WCF service with one
method “ProcessMessage” which
accepted an Xml string message as
argument. The internal app would
parse then deserialize the received
xml and process it accordingly.
The lead developer thought option two was the better option as it was “easier” to serialized/deserialize the xml. I thought the argument didn’t make sense because DataContracts are serialized and deserialized by WCF and by using WCF we had better typing of our data. In option 2 someone could call the WCF service and pass in any string. I believe option 1 presents a neater interface and makes the application more maintainable and useable.
Both options would still require parsing and validation of the original xml string at some point, so it may also be a question where is the recommended place to perform this validation.
I was wondering what the current thoughts are for passing this kind of information and what people’s opinions on both alternatives are.

Option 1 is suited if you can ensure that the client always sends serialized representations of data contracts to the server.
However if you need some flexibility in the serialization/deserialization logic and not get tightly coupled with DataContracts, then option 2 looks good. Particularly useful when you want to support alternate forms of xml (say Atom representations, raw xml in custom format etc)
Also in option 2 inside the ProcessMessage() method, you have the option of deciding whether or not to deserialize the incoming xml payload (based on request headers or something that is specific to your application).
In option 1, the WCF runtime will always deserialize the payload.

I recently asked a couple of questions around this area: XML vs Objects and XML vs Objects #2. You'll find the answers to those questions interesting.
For our particular problem we've decided on a hybrod approach, with the interface looking something like this:
// Just using fields for simplicity and no attributes shown.
interface WCFDataContract
{
// Header details
public int id;
public int version;
public DateTime writeDateTime;
public string xmlBlob;
// Footer details
public int anotherBitOfInformation;
public string andSoemMoreInfo;
public book andABooleanJustInCase;
}
The reason we use an xmlBlob is because we own the header and footer schema but not the blob in the middle. Also, we don't really have to process that blob, rather we just pass it to another library (created by another department). The other library returns us more strongly typed data.
Good luck - I know from experience that your option 2 can be quite seductive and can sometimes be hard to argue against without being accused of being overly pure and not pragmatic enough ;)

I hope I understood this right. I think it might make sense to have your gateway app handle all the deserialization and have your internal app expose WCF services that take actual DataContract objects.
This way, your deserialization of the TCP-based XML is more centralized at the gateway, and your internal apps don't need to worry about it, they just need to expose whatever WCF services make sense, and can deal with actual objects.
If you force the internal apps to do the deserialization, you might end up with more maintenance if the format changes or whatever.
So I think I would say option 1 (unless I misunderstood).

Should I bind directly to objects returned from a webservice?

Should I bind directly to objects returned from a webservice or should I have client-side objects that I bind to my gridcontrols? For instance if I have a service that returns object Car should I have a client side Car object that I populate with values from the webservice Car object?
What is considered best-practice?
In C# do I need to mark my classes as serializable or do something special to them?

This is a good question, which follows the sames lines as two questions I have asked myself:
Large, Complex Objects as a Web Service Result.
ASP.NET Web Service Results, Proxy Classes and Type Conversion.
Both of these may be a worthwhile read for you.
Heres my two bits:
Try to keep the return types of your Web Services to primitives where possible. This not only helps reduce the size of the messages, but also reduces complexity at the receiving end.
If you do need to return complex objects, return them as a raw xml string (I'll explain below).
What I then do is create a seperate class which represents the object and handles it's xml. I ensure the class can be instantiated from and serialized to xml easily. Then both projects (the web service and the client) can reference the DLL with the concrete object in, but there is none of the annoying coupling with the proxy class. This coupling causes issues if you have shared code.
For example (using your Car class):
Web Service (CarFactory) method BuyCar(string make, string model) is a factory method that returns a car.
You also write a Mechanic class that works on Car objects to repair them, this is developed without knowledge of the Web Service.
You then right a Garage class for your application. You add a web reference to the CarFactory service to get your cars, and then add some Mechanic's to your garage and then crack your knuckles and get ready to get some cars from the factory to get them working on.
Then it all falls over, when you get the result of CarFactory.BuyCar("Audi", "R8") and then tell your Mechanic.Inspect(myAudi) the compiler moans, because the Car is actually of type CarFactory.Car not the original Car type, yes?
So, using the method I suggested:
Create your Car class in its own DLL. Add methods to instantiate it and serialize it from/to XML respectively.
Create your CarFactory web service, add a reference to the DLL, build your cars as before, but instead of returning the object, return the XML.
Create your Garage adding a reference to the Mechanic, Car DLL and the CarFactory web service. Call your BuyCar method and now it returns a string, you then pass this string to the Car class, which re-builds its object model. The Mechanic's can happily work on these Car's too because everything is singing from the same hymn sheet (or DLL?) :)
One major benefit is that if the object changes in its design, all you need to do is update the DLL and the web service and client apps are completely decoupled from the process.
Note: Often it can be useful to then create a Facade layer two work with the web services and auto-generate objects from the XML results.
I hope that makes sense, if not, then please shout and I will clarify .

This really depends on what you are getting from the web service. If they are simple data transfer objects and you are only displaying data, then yes, you can bind. If you plan to edit the objects, it may not be usefull as you will need to track changes.
Do your objects and/or collections on the client track changes? If so you can use them.
If you have no change tracking, then you will need to track changes yourself, so you may need to translate the objects or wrap them in something to track changes.
Again, it really depends on what you are getting, what they support, what you are doing with them, as well as what response the server wants back for changes.

One thing you can do is to create client classes corresponding to the web service data contracts with any additional functionality that you want and set the web service reference to reuse existing types. Then there is no reason to create an additional wrapper class to bind to.

If you bind directly to the Web service types, you're introducing a coupling. Should the Web service change in future, this may have undesired side-effects that mean lots of code changes.
For example, what if you're using .asmx Web services today, then shift to WCF tomorrow? That might mean quite a few changes through your code if you've used types that WCF won't serialize.
It's often better in the long run to create specific client-side objects and then translate to and from Web service data contract types. It may seem a lot of work, but this is often repaid greatly when it's time to refactor, as your changes are localised in one place.

If you are the owner of both the web service and the client.
And you need the parameters of the web service calls to be complex classes which contain not only data but also behavior (actual coded logic) then you are in a bit of a pickle when developing these web services using web service frame works.
As suggested in the answer by Rob Cooper you can use pure xml as web service parameters and xml serialization, but there is a cleaner solution.
If you are using Visual Studio 2005 (probably applies the same for 2008), You can customize the way VS creates you proxy as described in this article:
Customizing generated Web Service proxies in Visual Studio 2005
This way you can tell VS to use your own classes instead of generating a proxy class.
Well when I think of it, it's pretty much same solution as proposed by Rob Cooper, with the little twist, that you wont be writing a Facade layer your self but will be using VS itself as this layer.

ASP.NET Web Service Results, Proxy Classes and Type Conversion

I'm still new to the ASP.NET world, so I could be way off base here, but so far this is to the best of my (limited) knowledge!
Let's say I have a standard business object "Contact" in the Business namespace. I write a Web Service to retrieve a Contact's info from a database and return it. I then write a client application to request said details.
Now, I also then create a utility method that takes a "Contact" and does some magic with it, like Utils.BuyContactNewHat() say. Which of course takes the Contact of type Business.Contact.
I then go back to my client application and want to utilise the BuyContactNewHat method, so I add a reference to my Utils namespace and there it is. However, a problem arises with:
Contact c = MyWebService.GetContact("Rob);
Utils.BuyContactNewHat(c); // << Error Here
Since the return type of GetContact is of MyWebService.Contact and not Business.Contact as expected. I understand why this is because when accessing a web service, you are actually programming against the proxy class generated by the WSDL.
So, is there an "easier" way to deal with this type of mismatch? I was considering perhaps trying to create a generic converter class that uses reflection to ensure two objects have the same structure than simply transferring the values across from one to the other.

You are on the right track. To get the data from the proxy object back into one of your own objects, you have to do left-hand-right-hand code. i.e. copy property values. I'll bet you that there is already a generic method out there that uses reflection.
Some people will use something other than a web service (.net remoting) if they just want to get a business object across the wire. Or they'll use binary serialization. I'm guessing you are using the web service for a reason, so you'll have to do property copying.

You don't actually have to use the generated class that the WSDL gives you. If you take a look at the code that it generates, it's just making calls into some .NET framework classes to submit SOAP requests. In the past I have copied that code into a normal .cs file and edited it. Although I haven't tried this specifically, I see no reason why you couldn't drop the proxy class definition and use the original class to receive the results of the SOAP call. It must already be doing reflection under the hood, it seems a shame to do it twice.

I would recommend that you look at writing a Schema Importer Extension, which you can use to control proxy code generation. This approach can be used to (gracefully) resolve your problem without kludges (such as copying around objects from one namespace to another, or modifying the proxy generated reference.cs class only to have it replaced the next time you update the web reference).
Here's a (very) good tutorial on the subject:
http://www.microsoft.com/belux/msdn/nl/community/columns/jdruyts/wsproxy.mspx