We Keep Coding

WCF returning different types of data

I'm just starting out really with WCF and Web Services in general. I have a pretty firm understanding on the purposes behind them and how they work, but I was wondering what the capabilities with them are if you wished to return something other than Text; such as a straight HTML form, or an image.
I've done some simple googling but alas all I can find is how to handle data passed from a form, rather than how to return a form.
I hope someone could give me a good starting point on what I should be looking at. I looked at a thread stating to look at Streaming with WCF but that may seem a bit excessive and was wondering if someone could give me some general advice and input.
Many thanks,
Ronald.

WCF services can return any object that the runtime can seralize. We return custom objects in our services with no issues, provided it's a .NET Client consuming them. Other languages may have to work harder to de-serialize complex objects.
(Meaning you have to write more code because non-Visual Studio IDE's probably won't know how to auto-generate the required client code.)

It probably depends on the actual binding but, for the sake of simplicity, assume that you bind your WCF service over http. Then, everything you pass to and from the service should somehow be translated to string. Simple types, ints, doules, strings, are easily convertible. Compound types - also, as they consist of simple types. When it comes to specific types like images or html forms, you always try to find a way to convert them at one side and convert back on the other side. In many cases the serializer can do it for you, for example if you return byte[], the data will be encoded as base64 string. If the serializer fails for some reason, you have to find your own way to pass your specific types. Please also remember that for WCF, it is you to select a particular serializer:
http://nirajrules.wordpress.com/2009/08/26/wcf-serializers-xmlserializer-vs-datacontratserializer-vs-netdatacontractserializer/

WCF is designed to build web API using standard or custom protocols. If you use the default configuration, WCF will output objects serialized using SOAP, but JSON is available too, for instance.
WCF is certainly able to output plain HTML, but it isn't designed with this goal in mind. It is meant to be used for communication between processes.

Using JSON with ASP.net vs IIS

I am in a situation where I possibly can influence a decision about some web service work on the C# side and need some nice info (ammunition) that I can use to choose what I think would be better(JSON).
Could anyone give me any help as to the pros and cons of each? One of things that I like about JSON is that is it much cleaner to maintain, it supports any web browser(i think) and it supports(i am pretty sure) the ability to send non-primitive objects across the pipe. If IIS can do all of those things then please inform me differently. thanks!

If the decision is for the data transport, is best to use JSON than xml, since the footprint is smaller, the translation from the string to the object is easily supported in all languages (javascript, C#), you can use JSON services to communicate cross domains (which fails if you are using an XML web service).
a non primitive data type is transformed to a JSON string, you can have really complex objects in JSON format, the only issue you may find is the Date transformation, but if the code is only for your company, that may not pose a problem since the serialization and de-serialization will be the same.
you can find the description of JSON here.
To be able to get more help you will have to be more specific on what do you want to do.

Not sure how to send complex data using Web Services

I've looked at quite a few of the questions on the site, but I'm still having trouble fulling understanding where to begin.
I've never done anything with webservices before, so bear with me.
The current project I've been assigned is to write a webservice that queries a database and returns the data back to the client. (using .NET 2008 programming in C#)
So far, I've been able to do basic data types no problem, but I'm not 100% sure where to go from there. I've been returning an XmlDocument type, but I'm not sure that that's the best way, or even the correct way to do it.
Currently creating an ASP.NET Web service, though it's been suggested I use a WCF Web service.
Can anyone shed light on where to go from here? Or perhaps a a link to a tutorial on sending and recieving large amounts of data via webservices?
EDIT: The answers are great so far, but I'm still not 100% sure how to answer. I think the webservice will be interacted with a combination of client programs, but also websites, if that is all possible... That's how new I am to this.

Depending on the structure of the data that you're sending back to the client, I wouldn't recommend using XmlDocument as the return type. It will add a lot of unnecessary bulk to your response.
You really didn't state the protocol that you want to support, but if you're transporting data via HTTP, then sending your data back to the client as a JSON-formatted string would streamline it better.
You can define that you're returning your complex type formatted as JSON like this:
[WebGet(ResponseFormat=WebMessageFormat.Json, UriTemplate="GetComplexObject/{id}")]
public MyComplexType GetComplexObject(int id){
//do work to get your object
return myObject;
}
WCF will take care of serializing your object as JSON if MyComplexType is defined as a DataContract...
[DataContract]
public class MyComplexType{
[DataMember]
String Name {get;set;}
}
If you're looking for REST-ful services, then WCF is probably the preferred approach using the WebHttp functionality.
The WCF team put together a great series of walk-throughs on using WCF WebHttp (which is new to .NET 4). They assume a little knowledge of web http programming, but they're pretty good and hopefully help put you on the right track.
I hope this helps!! Good luck.

http://msdn.microsoft.com/en-us/library/ms733127.aspx
WCF uses this concept of a data contract - which provides serialization help on complex objects.

If you decide to use WCF there is a tutorial available at : http://dotnetslackers.com/articles/ajax/JSON-EnabledWCFServicesInASPNET35.aspx .
In general, this article gives a walk through of building an ASP.NET web service that sends JSON.
JSON is faster than XML, and is becoming a standard for most new web services. I highly recommend the JSON.NET library for JSON serialization.

There are two ways that I have implemented this using a regular ASPX.NET web service:
Have the same underlying object libraries on the client and the server and functions to translate the data from the web service object to the client object.
Have the same underlying object libraries on the client and the server and pass data to/from the server as a string representation of the data object (usually XML format, but could be JSON or another similar format)
The first option I found is VERY cumbersome. The web service will claim that its versions of the libraries are unique, even if you have the same classes/objects on both the server and the client. Even if the namespace is the same, the object returned from the web service will have the web service namespace in it somewhere, so you have to write functions to convert them. I know of a way to fix this, but it is not worth the effort, at least not for me.
The second option is the one I am using right now. I again have one library on both client and server. It has objects that get and hold data from the database. I then have generic utility functions that serialize objects to and from XML strings. When I send data from the server I serialize it to an XML string on the server and deserialize it at the client. I do the reverse when sending data to the server. I also break up large amounts of data being passed to/from the web service to reduce errors and data transfer time.
WCF may be better. Never used it. But the above is what I have done with standard web services.

The best way to send data back to client it's throught xml, because almost all languages know how to handle xml document.
If you want to return something that it's in some way language dependent is't not worst to implement if you want your web service to be implemented using virtually all languages posible.
Another posibility is to return json objects.

LINQ to JSON in .NET

Is there such a thing as a JSON file? That is, *.json?
Can JSON be used in C# code without any JavaScript stuff, sort of as a replacement for XML?
And is there any official LINQ to JSON stuff around for C#?
I did find one website for my last question, but it took me to a page to download JSON.NET, and that page doesn't seem to mention anything about LINQ.

Yes, there is such a thing as a *.json file. The MIME type is application/json (source). JSON is a text-based format though, so you could hypothetically store JSON-formatted data in a text file with whatever extension you choose.
JSON can absolutely be used independently of JavaScript. In some cases, it's probably better suited to representing your data than XML. JSON.org has a great comparison page between JSON and XML.
JSON.org lists several JSON libraries for C# (for example, JSON.NET which you have already discovered), and most (if not all) of the collections that these libraries use should support LINQ. JSON.NET definitely does offer support for it. See here or here.

Everyone tends to stick with the JavaScriptSerializer (from the System.Web.Extensions library) when working with JSON in .NET. The handy part about this is the ability to create a custom JavaScriptConverter that will take custom objects and serialize them the way you chose. Likewise, you can make a deserialization method to receive in custom JSON formatting.
Though this of course depends on your application. Given that it's a Windows Forms application, is there any particular reason you'd chose JSON over storing the information natively or just use the XML format? If your application communicates with webpages, the JavaScriptSerializer is probably the best bet, though if you're using it to store/retrieve settings I'd use XML. And, if it's necessary to synchronize your application with a web-based one, just serialize to JSON when the time is ready.

You can deserialize your JSON file into C# objects. After that, you can query with LINQ on these objects.

Does C# have any built in objects for turning JSON text into manageable objects or do I need a third party library?

I have all this JSON text that I want to deserialize (or something) into an object with variables so I can run through it and add/change some things and then serialize it back to text. Is there something built in from Microsoft for this?

WCF has the DataContractJsonSerializer but I haven't used it myself - I've always gone for Json.NET which I've found to be broadly excellent.
I'd expect the WCF serializer to be a good fit if you're using WCF, but if you're writing a standalone app, I'd go for Json.NET. It's a pretty straightforward dependency. In particular, I like the fact that I don't actually have to model the classes directly in order to use Json.NET - I tend to use the "LINQ" side of the library which is a little like LINQ to XML, but applied to JSON. I deal directly in JArray, JObject, JToken etc and let Json.NET just do the parsing/formatting.

If you were using MVC, there are JSON methods, for output, but it is also possible to use action filters to deserialise json that is passed in. There are some quirks to this but it does work well with json submitted via jQuery etc.
Check this out

The fancy new "AJAX" stuff come with JavaScriptSerializer (built into Framework 3.5 and later, at least) It's not quite as flexible as, say, the XML serializers but it does the job in many cases.

I believe there are some built in, but I don't think they are terribly powerful by themselves. We have always used this library. It's very powerful and easy to use.
It's fantastic for serializing objects and lists or deserializing JSON.
http://json.codeplex.com/