this post doesn’t assume that u have any background on what the services is , so let’s start with a simple definitions

Service-oriented architecture :

simply it’s when your architecture is divided into separated components of code each one have it’s own functionality and they communicate together through a standard protocol of communication  , so these services or components can communicate interoperably also each component can serve multiple clients so it can be reused from different domains

Main benefits from SOA  

  • interoperability : for example a Java based project could use a .net based web service , because the use same communication standard
  • reuse : let’s assume a translator web service written once and could serve   millions of applications ( phone , desktop , web applications )
  • scalability  and agility : the same translator web service when i change in it’s functions or add new dictionaries or languages i don’t need to contact all the clients that use this service to rechange their code . i can just change the service and it’s changed in all clients because they don’t copy the code they only use the service . as long as i keep the same contract

WEB services : 

it’s a standard way for communication between web based applications in two  devices over a network (internet ) using XML , SOAP , WSDL  . XML is used to tag data and SOAP is the protocol of sending data  and WSDL is the web services describing language used to describe the available webservice . unlike normal web applications  WEBservices don’t need a browser also it doesn’t offer a GUI

web services examples :

  • bing search service
  • Microsoft translator service
  • IMDB service
  • AMAZON services
  • Twitter / Facebook services
  • Google API services

some drawbacks of WEBservices :

  • internet connection is required
  • transfer of large data across the internet may affects the performance

WCF services : 

a part of the .NET Framework that provides a unified programming model for rapidly building service-oriented applications that communicate across the web and the enterprise.

WCF ABC : 

  • address : it’s the uri of the service or where you can find the service on the web
  • binding : Specifies how a service is accessible. In other words: how the two parties will communicate in terms of transport (HTTP , TCP ,NamedPipe , Peer2Peer ,MSMQ)
  • contract : it’s simply what the service can do  ( the data and methods that the service can provide )
and now comes the Fun Part

DEMO1 : Building a WCF service:

open microsoft visual studio and open a new project
from the open window choose C# , WCF  and from the left choose new WCF service
after creating the new project  you will find the project explorer file called IService.cs
which is the Interface the service  the “web contract”  mentioned before which contains all the methods and data variables
that the service offers
methods offered by the services their definition is written and  followed by [OperationContract]
to add a new method in the service  add the function definition in the Iservice.cs  file followed by [OperationContract]
and in the file  service1.cs  add the function code inside the service1 class that implements the Iservice1 interface   
now you can run the service this is the landing page of the created  service in which you can find the service address from the service url of written in the page

DEMO2 : Consuming a WCF service from Windows phone 7 :

this will be a sample demo on how to consume a webservice in windows phone 7

the only difference between normal consumption of webservices  in WP7 and in any normal application

is that in normal application the communication is synchronous  ( application calls web services and services responds in the same time to the application )   but in WP7 it’s asynchronous communication ( in which when windows phone calls the webservice the response in not in the same time but when the web service is done with the response it fires an event in the windows phone and we need to write in the event handler the code that needed to utilize the response ) don’t get confused with the above comparison , it will be elaborated in the code below

to consume a webservice , let’s take for an example microsoft translator web service which we can find on this link

http://msdn.microsoft.com/en-us/library/ff512435.aspx

the service uri  (adress) is : http://api.microsofttranslator.com/V2/Soap.svc

now open a new windows phone project

from the project explorer right click the project icon and add service reference

copy paste the service URL :  http://api.microsofttranslator.com/V2/Soap.svc   in the address field and click Go

then change the namespace to  TranslatorService for example  in which all the Generated code will be under this namespace

once you added a reference to the web service now you can create new object of the service client class this object you will use it to call all the methods of the service

so open the mainpage.xaml.cs file and let’s write some code

let’s assume that the program that we are writing will translate  the sentence in the textbox1   in french and show it in a text Block called textblock1 when we click a button called button1

from the toolbox drag  a textbox  textblock and a button  , it’s supposed to look like this  after changing the page title and subtitle and labels of the components

double click the button to handle the on click event

in the on click event  , initialize a new object from the service  by writing the following code :

        private void button1_Click(object sender, RoutedEventArgs e)
        {
            TranslatorService.LanguageServiceClient myclient = new TranslatorService.LanguageServiceClient(); 

        }

after this myclient object is the object that i’ll use to call all the service methods

now we are going to call the translateasync  function to translate  it takes appid , text , from , to , contenttype , category

you can create your own appid or just feel free to use my temp one i’d generated

you can see the function documentation in the service website

        private void button1_Click(object sender, RoutedEventArgs e)
        {
            TranslatorService.LanguageServiceClient myclient = new TranslatorService.LanguageServiceClient();

            myclient.TranslateAsync("5F5CBEB15E4D9847AEB2C93B525EAC9B2A89465", textBox1.Text, "en", "fr", "text/plain", "general");
        }

we know that when the service is done with the response  a translatecompleted  event will be fired so we will add to this event a new event handler  with arguments inside the <>  and  the function name to be executed between the ()

        private void button1_Click(object sender, RoutedEventArgs e)
        {
            TranslatorService.LanguageServiceClient myclient = new TranslatorService.LanguageServiceClient();

            myclient.TranslateAsync("5F5CBEB15E4D9847AEB2C93B525EAC9B2A89465", textBox1.Text, "en", "fr", "text/plain", "general");

            myclient.TranslateCompleted += new EventHandler<TranslatorService.TranslateCompletedEventArgs>(translatecompleted);

        }
  • <TranslatorService.TranslateCompletedEventArgs>  is the event args to be passed to the invoked function when executed 
  • tanslatecompleted is then name of the function to be executed  of the new event handler 

and we will add the function implementation in a separate function

        private void translatecompleted(object obj , TranslatorService.TranslateCompletedEventArgs e )
        {

            textBlock1.Text = e.Result.ToString();

        }

the object ” e ” of type  TranslatorService.TranslateCompletedEventArgs

contains the event arguments and it’s attribute Result contains the results of the invoked method in the webservice

which will be the translated text which then we will convert it to string and display it in the textblock1

the whole file would look like this :

now we are done let’s compile Run and try to see if there will be any bugs

now you are supposed to know:

  • what’s the SOA , and webservices , WCF services
  • how to build a WCF services
  • how to consume a web service in windows phone 7 applcations
imagine the unlimited number of applications that you can build and creative ideas you can generate depending on existing webservices that gives u a lot of capabilities
and always remember those available services when Generating ideas for WP7 applications
for any Questions or feedback don’t hesitate to ask me here or  on twitter @hadyelsahar 
and to keep updated with all Microsoft  similar Events  follow the hashtag #mspegypt and the twitteraccount   @mspegypt  on twitter  or our Fanpage
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