Your first C# Web Service (2024)

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Introduction

Creating your first web service is incredibly easy. In fact, by using the wizards in Visual Studio. NET you can have your first service up and running in minutes with no coding.

For this example I have created a service called MyService in the /WebServices directory on my local machine. The files will be created in the /WebServices/MyService directory.

A new namespace will be defined called MyService, and within this namespace will be a set of classes that define your Web Service. By default the following classes will be created:

There are also a number of files created:

The class for your service that is created by default is called (in this case) WebService1, and is within the MyService namespace. The code is partially shown below.

namespace MyService{ ... /// <summary> /// Summary description for WebService1. /// </summary> [WebService(Namespace="http://codeproject.com/webservices/", Description="This is a demonstration WebService.")] public class WebService1 : System.Web.Services.WebService { public WebService1() { //CODEGEN: This call is required by the ASP+ Web Services Designer InitializeComponent(); } ... [WebMethod] public string HelloWorld() { return "Hello World"; } }}

A default method HelloWorld is generated and commented out. Simply uncomment and build the project.Hey Presto, you have a walking talking WebService.

A WebService should be associated with a namespace. Your Wizard-generatedservice will have the name space http://tempuri.org. If you compile and run theservice as-is you'll get a long involved message indicating you should choose anew namespace, so we add the namespace, and the WebService description asfollows:

[WebService(Namespace="http://codeproject.com/webservices/", Description="This is a demonstration WebService.")]public class WebService1 : System.Web.Services.WebService{ ...

To test the service you can right click on WebService1.asmx in the Solution Explorer in Visual Studio andchoose "View in Browser". The test page is shown below,

When invoked this returns the following:

Getting the demo application to run

If you downloaded the source code with this article then you will need tocreate a directory 'WebServices' in your web site's root directory and extractthe downloaded zip into there. You should then have:

\WebServices\WebServices\bin\WebServices\WebService1.asmx...

Navigating to http://localhost/WebServices/WebService1.asmx won't showyou the WebService because you need to ensure that the webservice's assembly isin the application's /bin directory. You will also find that you can't load upthe solution file MyService.sln. To kill two birds with one stone youwill need to fire up the IIS management console, open your website's entry,right click on the WebServices folder and click Properties. Click the'Create' button to create a new application the press OK. The /WebServices directoryis now an application and so the .NET framework will load the WebServiceassembly from the /WebServices/bin directory, and you will be able toload and build the MyService.sln solution.

Extending the example

So we have a WebService. Not particularly exciting, but then again we haven't exactly taxed ourselves getting here. To make things slightly more interesting we'll define a method that returns an array of custom structures.

Within the MyService namespace we'll define a structurecalled ClientData:

public struct ClientData{ public String Name; public int ID;}

and then define a new method GetClientData. Note the use ofthe WebMethod attribute in front of the method. This specifiesthat the method is accessible as a WebService method.

[WebMethod]public ClientData[] GetClientData(int Number){ ClientData [] Clients = null; if (Number > 0 && Number <= 10) { Clients = new ClientData[Number]; for (int i = 0; i < Number; i++) { Clients[i].Name = "Client " + i.ToString(); Clients[i].ID = i; } } return Clients;}

If we compile, then navigate to the the .asmx page then we are presented witha form that allows us to enter a value for the parameter. Entering a non-integervalue will cause a type-error, and entering a value not in the range 1-10 willreturn a null array. If, however, we manage to get the input parameter correct,we'll be presented with the following XML file:

It's that easy.

Caching WebServices

Often a WebService will return the same results over multiple calls, so itmakes sense to cache the information to speed things up a little. Doing so inASP.NET is as simple as adding a CacheDuration attribute to yourWebMethod:

[WebMethod(CacheDuration = 30)]public ClientData[] GetClientData(int Number){

The CacheDuration attribute specifies the length of time in seconds that themethod should cache the results. Within that time all responses from theWebMethod will be the same.

You can also specify the CacheDuration using a constant member variable in your class:

private const int CacheTime = 30;// seconds[WebMethod(CacheDuration = CacheTime)]public ClientData[] GetClientData(int Number){

Adding Descriptions to your WebMethods

In the default list of WebMethods created when you browse to the .asmx fileit's nice to have a description of each method posted. The Descriptionattribute accomplishes this.

[WebMethod(CacheDuration = 30, Description="Returns an array of Clients.")]public ClientData[] GetClientData(int Number){

Your default .asmx page will then look like the following:

There are other WebMethod attributes to control buffering, session state andtransaction support.

Deploying the WebService

Now that we have a WebService it would be kind of nice to allow others touse it (call me crazy, but...). Publishing your WebService on your serverrequires that your solution be deployed correctly. On the Build menu of Visual Studio is a "Deploy" option that, when first selected, starts a Wizard that allows youto add a Deployment project to your solution. This creates an installation packagethat you can run on your server which will create the necessary directories, setthe correct parameters and copy over the necessary files.

This doesn't really give you an idea of what, exactly, is happening, sowe'll deploy our MyService manually.

Deploying the application is done using the steps in Getting the demo application to run. We need to create a directory for our service (oruse an existing directory) for our .asmx file, and we need to have the service'sassembly in the application's bin/ directory. Either place the .asmx file ina subdirectory on your website and place the assembly in the /bin folder in yourwebsite's root, or place the /bin in the subdirectory containing the .asmx file andmark that directory as an application (see above).

If you choose to create a separate directory and mark it as an application thenWithin this directory you need to add the following files and directories:

Conclusion

Writing WebServices is extremely easy. Using the Visual Studio. NET wizards makeswriting and deploying these services a point and click affair, but even if you wishto do it by hand then the steps involved are extremely simple.