Visual CSharp 2005 Express Edition (2006) [eng]

Chapter 15

6.Click the plus sign next to the Delayed Stock Quote, and scroll down in the browser. You now see the full description of the Web service, as shown in Figure 15-7.

7.Click the http:// address displayed as the Interface Definition. You now see the definition displayed, and the Add Reference button is enabled. The definition for the Web service is shown in Figure 15-10.

Figure 15-10

It is not a bad idea to copy and paste the information displayed here into a text file, or better yet, press Ctrl + Print Screen and save it to a file. While you can look in the object browser to get this information, it is nice to have it displayed in this format. Otherwise, you will have to go to the provider’s Web site to locate this information, and a lot of times they won’t have it documented as well.

8.Click Add Reference. The Web reference is now created in your project.

Because the UDDI is so dynamic, here is the actual URL for the Web service as well:

http://ws.cdyne.com/delayedstockquote/delayedstockquote.asmx.

At this point, you won’t be actually using the Web service that you have created a reference to. You will use it shortly, but before that, I want to show you how to locate and use a reference that you get from searching the Internet directly. I will come back to this Web service to show you how to use it in your code.

Searching for Web Services on the Web

This task and the task covered in the next section use nearly the same method, except here you use a search engine such as Google to locate a particular type of Web service. For example, if I want to locate a weather Web service that could give me the weather for particular locations, I would go to Google and search for “weather Web service”. When I do, I see the results shown in Figure 15-11.

264

Using Web Services from Your C# Application

Figure 15-11

As you can see from 15-11, I immediately found a Web service that is what I am looking for. In fact, this service is used in an example that you perform later in this chapter, so you will see how to include a Web service that isn’t found using C# Express directly. When clicking the link for GlobalWeather Web Service, the Web services page is displayed with a link to the Web service itself. Further information about the service is given, as shown in Figure 15-12.

The data for this Web service is supplied by NOAA, which is pretty amazing if you think about the fact that you are actually using data provided by the National Oceanic and Atmospheric Administration with less then an hour between updates.

Scrolling down the page, you can see the exact details on how to use this Web service in an application. You can see the methods and properties that are exposed for the Web service, as well as details on the link you need to create a Web reference, in Figure 15-13.

265

Chapter 15

Figure 15-12

Figure 15-13

266

Using Web Services from Your C# Application

When on the page displayed in Figure 15-13, you can see the WSDL URL listed. At this point you can highlight the string, up to where it says (Simplify this WSDL). Then copy and paste it into the address in the Add Web Reference dialog box discussed in the previous section. Once you do that and press Enter, the Web server details appear, as shown in Figure 15-14.

Figure 15-14

This saves you from all the steps taken in the previous section to locate the WSDL URL that was eventually provided by the UDDI directory.

Notice that the description for this Web service isn’t as detailed as the one displayed for the Delayed Stock Quote Web service in Figure 15-10. Also, not all Web services are as easy to find or as nicely supported as the ones described in this book. Also, all Web services are subject to change at the whim of the developers who create them.

Now it is your chance to create a Web reference to the GlobalWeather web service. For this Try It Out you use your Web browser along with the project that you have been using in this chapter.

1.Open your browser.

2.Type www.google.com in the address bar.

3.Type Weather Web Service in the Search field.

4.Click the Google Search button. The list of search results appears.

5.Click the first choice in the list, GlobalWeather Web Service. You are taken to the Web site for the Web service.

267

Chapter 15

6.Scroll down the Web page until you now see the definition for the Web service as was displayed in Figure 15-13.

7.Highlight the WSDL URL.

8.Choose Edit Copy.

9.Switch back to the C# Express project you created for this chapter.

10.Choose Project Add Web Reference . . . .

11.Place the cursor in the URL field, and click Edit Paste. The WSDL URL is copied into the URL field of the Add Web Reference dialog box.

12.Click Go. The Global Web Service definition is displayed in the browse window.

13.Click Add Reference. The Web reference is created in the project, and you are ready to go with two Web services in your project.

There you go; you have now created Web references using two different methods. The method you use to locate the Web service will depend on whether you can find the Web service faster using one way than the other. The way just shown it is my preferred method, since you can specify what you are looking for a little bit more precisely than the first method you used in C# Express.

One last thing to keep in mind when comparing Web services is to make sure they have the various methods that you need to accomplish the job.

Now that you have the Web references in your project, it is time to do something with them. To make it as straightforward as possible, start off by creating the form and utilizing the DelayedStockQuote Web service, for which you set the Web reference earlier in this chapter. The form used to display the information from the Web service is shown in Figure 15-15.

Figure 15-15

268

Using Web Services from Your C# Application

Using the Web Ser vice in Your Code

The really cool thing about using Web services in your applications is that they don’t take much more to use than any of the other classes in .NET, and a lot less than many. Of course, how much work it takes to utilize them will depend on what features are included. The more features a Web service has, then possibly the more effort it will take to use them — although this is not necessarily true. Many services, such as

the GlobalWeather Web service, have an extensive object model, but also provide some methods and properties that can be used in a fairly straightforward manner.

Coding for the DelayedStockQuote Web Service

To get going, you will learn how to integrate the DelayedStockQuote in your application. When working with a Web service, you need to learn what classes and their methods and properties are available for use. One of the ways to do this is to examine the Web service classes in the Object Browser. If you were to do so with DelayedStockQuote, you would see that it is in fact only one of the classes that is used. The other useful thing to note is that the method you will want to use is called GetQuoteDataSet. This method takes a stock symbol as a parameter, and a license. Since you are only going to be testing the Web service, you will pass “0” as the license key. By double-clicking the new Web reference in the Solution Explorer, you can see that the Web service references have defined a namespace with types for you to use in your program.

While not all Web services do so, many let you test their services out for a trial period.

Knowing what you now know about the Web service, you can declare the necessary objects and get to work. Now it is just a matter of using the same syntax you have been using throughout the book:

com.cdyne.ws.DelayedStockQuote wsStock = new com.cdyne.ws.DelayedStockQuote();

Once this occurs you, get full IntelliSense on the properties and methods, as you can see in Figure 15-16.

You should be very familiar with the code displayed. I tend to use the full path of the Web services I use so I can remember them as I work with them. The line of code declares the variable wsStock as a DelayedStockQuote object. Next, you assign a DataSet object that is returned from the

GetQuoteDataSet method:

DataSet dsStocks = wsStock.GetQuoteDataSet(this.txtStockSymbol.Text, “0”);

DataSets were first introduced in Chapter 12. The last thing to do is to assign the dsStocks DataSet to the DataGridView control on the form. The DataGridView was also discussed in Chapter 12.

this.dataGridView1.DataSource = dsStocks.Tables[0];

Some code can be added for exception handling and such.

269

Chapter 15

Figure 15-16

By now, creating this form, and even the code introduced in this section, should be pretty old hat. As you keep using these examples and others, you will start to find it is just a matter of learning how to use the new classes that have been created. Using the project you created in this chapter:

1.Select Project Add Windows Form . . ., and name it as desired. For the purpose of this example, I named it frmGetQuotes.cs.

2.Add a Label (Text property set to “Stock Symbol”), TextBox (Name property set to txtStockSymbol), and Button (Name property set to btnGetStock) control as displayed in Figure 15-17.

3.Drag and drop a DataGridView control from the Toolbox onto the form, positioning as shown in Figure 15-16. Leave the name of the DataGridView of the control as it was, and just make a note of it.

4.Set the Anchor property to be Top, Bottom, Left, and Right.

5.Double-click the btnGetStock button. The code file is displayed with the Click routine created as shown here:

270

Using Web Services from Your C# Application

private void btnGetStock_Click(object sender, EventArgs e)

{

}

Figure 15-17

6.Type the following lines of code inside the opening and closing curly brackets:

com.cdyne.ws.DelayedStockQuote wsStock =

new com.cdyne.ws.DelayedStockQuote();

DataSet dsStocks = wsStock.GetQuoteDataSet(this.txtStockSymbol.Text, “0”);

this.dataGridView1.DataSource = dsStocks.Tables[0];

The complete code now looks as follows:

private void btnGetStock_Click(object sender, EventArgs e)

{

com.cdyne.ws.DelayedStockQuote wsStock =

new com.cdyne.ws.DelayedStockQuote();

DataSet dsStocks = wsStock.GetQuoteDataSet(this.txtStockSymbol.Text, “0”);

this.dataGridView1.DataSource = dsStocks.Tables[0];

}

7.Add a button to the main form created for the chapter. Add the following line of code, changing the name of the form called to what you named it:

271

Chapter 15

private void btnCheckStocks_Click(object sender, EventArgs e)

{

frmGetQuotes frmCurr = new frmGetQuotes(); frmCurr.Show();

}

8.Press F5 to build and run the application.

By typing in a stock symbols such as MSFT and FOX, you can test the Web service. Another good extension of this would be to access a Web service to populate a drop-down with the stocks available. When you want to bring back information on more than one stock, separate the symbols in the text box with a comma.

I have noticed that with most Web services the first time you call them in an application, the performance is somewhat slower than I liked. However, when you call them a consecutive time in the same instance of the application, the performance is much improved. This will, of course, depend on the Web services themselves.

Coding for the GlobalWeather Web Service

While the coding for the example using this Web service is a little more extensive, it is because more information will be displayed. Even then, it is actually pretty straightforward to display quite a bit of information. In this example, with an airport code supplied, not only will you display the current

temperature but also the current station information for sky coverage, visibility, and wind. You can see the form in action in Figure 15-18.

Figure 15-18

The example in Figure 15-18, which you will create, shows not even the tip of iceberg of the information available in this Web service, but maybe a seagull sitting on the tip of the iceberg. Each piece of weather information displayed in Figure 15-18 is made up of smaller properties strung together for convenience.

272

Using Web Services from Your C# Application

Each of the lines displayed happened to reflect a class of the WeatherReport class, which you can see in the Object Browser, shown in Figure 15-19.

Figure 15-19

You can see the information used in the example, and more. For this Web service, there are several steps you need to take when utilizing the classes within the service. The first object you need to create is a GlobalWeather object, as shown with the following code:

com.capescience.live.GlobalWeather wsWeather =

new com.capescience.live.GlobalWeather();

Once you have instantiated this object, you then have a number of methods you can execute to retrieve information various ways. For the purpose of this example, you will use the getWeatherReport method to retrieve the properties of the WeatherReport object. The instantiation of the WeatherReport object and calling of the getWeatherReport method can be seen here:

273