What is old, is still oldBeing a C#/Web App programmer for most of my life, SOAP XML Web Services have been a staple of development. Just - it is how you did everything. It was perfect. Visual Studio would build all your classes for you based upon your WSDL and viola - you were up and running within a few clicks of a button.
Which, was nice.
Once I started pushing to "The Cloud" to build Mobile Apps which can communicate with one another or do remote storage - I quickly learned how bad XML based Web Services actually were. To which, my favorite quote:
XML is like violence: if it doesn't solve your problem, you're not using enough of it.After trying to consume Web Services with iOS - it became painfully obvious that it simply doesn't work well.
My frustrations grew worse when trying to use Microsoft SharePoint Web Services. Which, in their infinite wisdom, returned XML within XML. Yes, brilliant.
There are several factors that come into play with Web Services and mobile development.
ParsingXML parsing of the Web Service HTTP Response is necessary. This is tedious. In iOS, XML parsing just wasn't fun. You had to build extensive classes to handle and parse out things how you desired. Then, if you want to port that to Android, you have to do the same.
Consuming Web Services is expensive. And, this means more than just dollars and cents, but it does mean so in dollars and cents, when you consider metered rates for mobile devices.
Lets look at this example to get a ticker price of a stock
To send a 3 character stock symbol, we have to send 223 characters in the request body. While, this may not seem like a lot to most - when you are trying to squeeze in efficiency to your product, reducing your payload by 98.5% is pretty dramatic.
Cross Platform Ease
With Web Services, as stated before, XML parsing is a bear. It just isn't fun. With JSON, you can easily port your "Parsing Engine" over from iOS to Android and Windows Phone. In our latest project, going from iOS to Android, converting the parser took a whole 30 minutes of my time.
What to use
Plus, there are tons of amazing libraries out there for C# and iOS to do JSON. For C#, I love Newtonsoft's JSON library. With iOS, you simply cannot beat JSONKit. With Android, the built in libraries from org.json work perfectly.
I'll write more on this later, but I just wanted to put it out there, stay away from Web Services if you develop Mobile Apps. Rewrite the Web Services if you have to, just - don't use them. You'll thank me later.