Home > Articles > Programming > Windows Programming

  • Print
  • + Share This
This chapter is from the book

Implementing the Web Service Client

Although being able to access a Web Service from a Web browser is nice, a more realistic use is to create custom client programs that access a Web Service remotely, such as Web pages and standalone applications. To demonstrate how to create such programs, we'll create two different clients for our TimeUtils Web Service: a console application and a Web page.

TIP

You can create Web Service clients easily by using Visual Studio.NET; we'll explain how to create them a little later. However, to show some of the "plumbing" behind Web Services, let's continue using a text editor to create our client programs.

Before creating the client to our TimeUtils application, we need to create a proxy class. A proxy class allows us to call the GetTime method without worrying about how to connect to the server and how to pass and return parameters to and from the method. In general, a proxy is an object that wraps up method calls and parameters, forwards them to a remote host, and returns the results to us. Proxies serve the role as a middleman on the client computer.

.NET comes with a special utility called WSDL.exe for creating Web Service proxies. As you might imagine from the utility's name, WSDL.exe takes a Web Service's WSDL description and creates a proxy. Follow these steps to create the proxy with WSDL.exe:

  1. Open a Visual Studio.NET command prompt (from the Start menu, choose Visual Studio.NET, Visual Studio.NET Tools, and then Visual Studio.Net Command Prompt). This DOS command prompt contains all the paths for the .NET tools.

  2. Create a new directory for the client projects, such as C:\src\timeclient.

  3. Type the following command at the prompt (try to fit the entire command at the second prompt onto one line):

    C:>cd src\timeclient
    C:\src\timeclient> wsdl /l:CS /n:WebBook
      /out:TimeProxy.cs
      http://localhost/TimeService/TimeUtils.asmx?WSDL

    This command creates the TimeProxy.cs file, which you can use in your client applications:

    • /l:CS tells the utility to create the proxy using C#.

    • /n:WebBook specifies a namespace for the WSDL tools to use when it creates the proxy class. You can use any namespace name you want.

    • /out:TimeProxy.cs specifies the name of the output file.

    • The last parameter is an URL for getting a WSDL description of the Web Service. You can also specify a file containing WSDL. However, if you use an URL, as in this example, the utility will automatically browse to the Web address and use the WSDL file that it finds.

  4. Compile the new proxy file:

    C:\src\timeclient> csc /t:libarary TimeProxy.cs

The proxy that the WSDL.exe utility creates should look like the file shown in Listing 3.

Listing 3—An Automatically Generated Proxy Class for the TimeUtils Client

 1: //-----------------------------------------------------------------------
 2: // <autogenerated>
 3: //   This code was generated by a tool.
 4: //   Runtime Version: 1.0.2914.16
 5: //
 6: //   Changes to this file may cause incorrect behavior and will be lost
 7: //   if the code is regenerated.
 8: // </autogenerated>
 9: //-----------------------------------------------------------------------
10:
11: //
12: // This source code was auto-generated by wsdl, Version=1.0.2914.16.
13: //
14: namespace WebBook {
15:   using System.Diagnostics;
16:   using System.Xml.Serialization;
17:   using System;
18:   using System.Web.Services.Protocols;
19:   using System.Web.Services;
20:
21:   [System.Web.Services.WebServiceBindingAttribute(
22:     Name="TimeUtilitiesSoap",
23:     Namespace="http://tempuri.org/webservices")]
24:   public class TimeUtilities : 
25:     System.Web.Services.Protocols.SoapHttpClientProtocol {
26:
27:     [System.Diagnostics.DebuggerStepThroughAttribute()]
28:     public TimeUtilities() {
29:       this.Url = "http://localhost/TimeService/TimeUtils.asmx";
30:     }
31:
32:     [System.Diagnostics.DebuggerStepThroughAttribute()]
33:     [System.Web.Services.Protocols.SoapDocumentMethodAttribute(
34:       "http://tempuri.org/webservices/GetTime",
35:        RequestNamespace="http://tempuri.org/webservices",
36:        ResponseNamespace="http://tempuri.org/webservices",
37:        Use=System.Web.Services.Description.SoapBindingUse.Literal,
38: ParameterStyle=System.Web.Services.Protocols.SoapParameterStyle.Wrapped)]
39:     public string GetTime() {
40:       object[] results = this.Invoke("GetTime", new object[0]);
41:       return ((string)(results[0])); 
42:     }
43:
44:     [System.Diagnostics.DebuggerStepThroughAttribute()]
45:     public System.IasyncResult
46:       BeginGetTime(System.AsyncCallback callback,
47:              object asyncState) {
48:       return this.BeginInvoke("GetTime", new object[0],
49:           callback, asyncState);
50:     }
51:
52:     [System.Diagnostics.DebuggerStepThroughAttribute()]
53:     public string EndGetTime(System.IAsyncResult asyncResult) {
54:       object[] results = this.EndInvoke(asyncResult);
55:       return ((string)(results[0]));
56:     }
57:   }
58: }

The proxy file contains a new definition for the TimeUtilities class, different from the one created earlier in Listing 1. This new definition is the version that all our client programs will use. Although this new class is defined differently than the original created for the Web Service, this new TimeUtilities class will work the same way for any client program that uses it. Rather than execute code directly, this new class will call the Web Service to execute each method.

Notice also the two new methods in the proxy class, BeginGetTime (Lines 44–50) and EndGetTime (Lines 52–56). These methods are created so that we can call the Web Service asynchronously. This means that we can call the Web Service in our client program and then do other work immediately. Then, when the Web Service returns a result, we can process the results at that time. This asynchronous method for calling remote Web Services might not be responsive because of a slow network connection.

Now that we've created our proxy class, we can create client programs that use our Web Service. To begin, let's create a simple console application to call the Web Service. The client is shown in Listing 4.

Listing 4—CallService.cs: A Console Application That Calls the TimeUtils Web Service

using System; 
using WebBook;

namespace WebBook
{
 public class CallService
 {
  public static void Main()
  {
   TimeUtilities remoteService = new TimeUtilities();

   Console.WriteLine("Calling web service...");

   Console.WriteLine(remoteService.GetTime());
  }
 }
}

If you save the CallService.cs client in the TimeClient project directory that you created, you can compile it by using this command:

csc CallService.cs /r:TimeProxy.dll

This command creates a file named CallService.exe in the client directory, which you can run now. For this command to work, you must have compiled the proxy class in Listing 3 according to the instructions in step 4 of this section.

After running the CallService.exe program you created, you should see output like the following:

Calling web service...
The current time on the server is: 7/9/2001 12:19:08 PM

Creating a Web Service Client

Now that you've seen how to create a Web Service proxy and client program manually, let's use Visual Studio.NET to make a Web page that calls the TimeUtils Web Service. Visual Studio.NET automates the process by creating a proxy file using a wizard. For the example in this section, we'll create an ASP.NET page that calls the Web Service.

To create the client application, follow these steps:

  1. Create a new ASP.NET Web application by selecting New Project on Visual Studio's start page.

  2. In the New Project dialog, select Visual C# Projects in the Project Types list and then select ASP.NET Web Application from the Templates list. Name the Web application ASPClient and click OK (see Figure 3).

    Figure 3 The New Project dialog.

  3. From the Project menu, choose Add Web Reference. You should see a dialog similar to Figure 4.

    Figure 4 The Add Web Reference dialog.

  4. In the Address text box, enter http://localhost/TimeService/TimeUtils.asmx and then click the Add Reference button to create a proxy file for the Web Service and add it to your project.

  5. Change the Page_Load method in WebForm1.aspx to use the code in Listing 5.

  6. Run the project.

Listing 5—Page_Load Method for the Visual Studio Client ASP.NET Page

private void Page_Load(object sender, System.EventArgs e)
{
  localhost.TimeUtilities remoteService = new localhost.TimeUtilities();
  Response.Write(remoteService.GetTime());
}

If the remote Web Service resides on another machine, the localhost string in Listing 5 changes to the name of that machine. After running the project, you should see a screen similar to Figure 5.

Figure 5 The ASP.NET client for the Web Service.

  • + Share This
  • 🔖 Save To Your Account

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.

Overview


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information


To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information


Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children


This site is not directed to children under the age of 13.

Marketing


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information


If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information


Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents


California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure


Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact


Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice


We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020