Integrating the Google Web Service Into ASP.NET

Integrating the Google Web Service Into ASP.NET
Google now offers the functionality of its search engine through a Web service.Over the past couple years, Google has become the most popular search engine used on the Web. Building upon its popularity, Google has developed additional search accessories and interfaces for both personal and commercial use. The most powerful interface offered by Google is exposure of its database and search capabilities through the use of a Web service.
If you're not already familiar with Google, it is located at http://www.google.com/ and is commonly known for its creative display logos. According to the Neilson NetRatings of January 2003, Google is rated as the top search engine on the Web with a 29.5% share of the market followed by Yahoo and MSN. In addition to an extremely robust standard search service, Google offers searches in various categories including images, groups, directory, and news. Figure 1 shows the Google home page.
Integrating the Google Web Service Into ASP.NET (Cont.)
Google Web Service API
Currently the Google Web service application programming interface (API) is in its beta testing period, hence support for using the API is limited. However, Google has fully documented the Google Web service API online at http://www.google.com/apis/index.html. You can also get minimal technical support via email at api-support@google.com. You'll find answers to many questions in the discussion group at google.public.web-apis.
Beta Terms and Limitations
Let me make you aware of a few additional notes regarding the use of the Google Web service API due to it being in beta. The service will return only 10 results per search processed although the estimated total number of results may be greater than 10. Also, with a developer license you can only make a maximum of 1,000 searches per day. Google is also adamant that you can only use the Web service API for personal use.
Obtaining a License Key
The best part of using the Google Web service API is that it is free to use in accordance with the terms and limitations listed in the section titled Terms and Limitations. You'll find it extremely simple and quick to obtain a license key. The license key issued by Google must accompany all searches processed.
" ________________________________________
With a developer license you can only make a maximum of 1,000 searches per day. You must obtain a developer license key from Google prior to using their Web service.
________________________________________ "
To obtain a license key, register with Google to create a new account in step 2 at http://www.google.com/apis/index.html. Once you've created a new account, Google will e-mail the license key to the email address entered.
Referencing the Web Service
Once you have your license key, you need to configure your application to consume the Google Web service. In Visual Studio .NET you add a Web Reference to the WSDL document. Remember that your WSDL document describes how to interact with the Web service and what functionality the Web service exposes.
To consume the Google Web service, start Visual Studio .NET and open the project where you want to use the Google Web service. Right-click on the project in the Solution Explorer and select Add Web Reference.
When the Add Web Reference dialog box appears, enter http://api.google.com/GoogleSearch.wsdl in the URL dropdown and click Go. If your application cannot locate the Web service, verify that the Google Web service API is online. Also verify that you have adequate access to the Web from your development machine. Figure 3 shows the Add Web Reference dialog box with the Google Web service located online. Once your application has located the Web service, enter an optional name for the Web service and click Add Reference. A folder named Web References should appear in the project folder structure with the newly added Google Web service listed inside of it.


Figure 3. The Add Web Reference dialog box with the Google Web service located. &


Resources
You can find the Google search engine at http://www.google.com/.
Point your browser to http://www.google.com/options/ to find the Google toolbar for Internet Explorer 5 or higher and other accessories.
Go to http://www.google.com/apis/index.html to find the Google Web service API documentation.
Shannon Horn
________________________________________


Integrating the Google Web Service Into ASP.NET (Cont.)
Calling the Web Service
Once you've added a Web Reference for the Google Web service, the functionality exposed by the Web service should be available to your code. The Web service will be referenced by prefixing it with the root namespace name for the project that the Web Reference was added to. The Google Web service exposes three methods: doGetCachedPage, doSpellingSuggestion, and doGoogleSearch.
" ________________________________________
The URL to use when creating a Web Reference to the Google Web service API is http://api.google.com/GoogleSearch.wsdl.
________________________________________ "
Use the doGetCachedPage method to submit a URL to the Google Web service and receive the contents of the URL that the Google database has cached. The Google search engine crawls the Web gathering new content and pages and indexes them in the Google database. When the search engine encounters a URL, it takes a snapshot of the contents of the URL and stores the snapshot in the database. Thus, the contents returned by the doGetCachedPage method will only be as recent as the last time that the Google search engine encountered the URL requested. An identifying key and the URL are passed to the method as strings and the resulting content is returned as System.Byte Base64 encoded text.
You'll use the doSpellingSuggestion method to create the same signature functionality found on the Google home search page. When you perform a search, Google lists a possible spelling correction suggestion i at the top of the page so that if a user misspells a key search term, the search engine will offer the correct spelling of the term. The doSpellingSuggestion accepts a word or phrase containing up to 10 individual words and 2048 bytes and it returns a text string with the suggested spelling term.
The doGoogleSearch method is the heart and soul of the Google Web service API. It performs the actual search functionality based on supplied search criteria. Table 1 lists the possible arguments that you can pass to the doGoogleSearch method. The key argument is the license key that Google issued. You must include it in any search requests made to the Google Web service. The q argument is the term that you want Google to search.
In my example project for this article I've incorporated the Google Web service into an ASP.NET page and my application consumes the Google Web service directly in the code behind page. To call the Google Web service, my application first creates an instance of the GoogleSearchService object as shown in this code snippet:
// Declare a new instance of the Google Search
// Service object.
Google.GoogleSearchService googleSearchService =
new Google.GoogleSearchService();
This code creates an instance of the GoogleSearchService using an identifier called googleSearchService. Next the application submits a search to the Web service by calling the doGoogleSearch, it pass the appropriate arguments, and then stores the results into a new instance of the GoogleSearchResult object. The snippet below illustrates the call to the doGoogleSearch function member.

// Declare a new instance of the Google Search
// Result object to hold the results of the query.
Google.GoogleSearchResult googleSearchResult =
googleSearchService.doGoogleSearch(_
"Oy5qm/bQFHJjWHJQjmyhFhLUidsqssF8", _
txtSearchCriteria.Text.ToString(),
startRange,_
numberResults,_
false,"",true,"","","");In this code snippet, I create a new instance of the GoogleSearchResult object using an identifier of googleSearchResult. GoogleSearchResult will hold a collection of search results returned by the GoogleSearchService.doGoogleSearch function member. The snippet above also illustrates the call made to the doGoogleSearch function member with the appropriate arguments. You can see the license key as the first argument. My application pulls the query terms from a textbox named txtSearchCriteria on the ASP.NET page. It passes a variable named startRange as the starting row number to be returned by the search, and it passes a variable named numberResults as the number of results for the search to return. &


// Build a table based on the results of the
// query.
dtResults.Columns.Add(new
DataColumn("Title",typeof(string)));

dtResults.Columns.Add(new
DataColumn("Summary",typeof(string)));

dtResults.Columns.Add(new
DataColumn("URL",typeof(string)));

// Iterate through the results collection and
// build a row for each result.
for (int resultCounter = 0; resultCounter <
numberResults;resultCounter++)
{

drResult = dtResults.NewRow();

drResult["Title"] =
googleSearchResult.resultElements[resultCounter].title;

drResult["Summary"] =
googleSearchResult.resultElements[resultCounter].snippet;

drResult["URL"] =
googleSearchResult.resultElements[resultCounter].URL;

dtResults.Rows.Add(drResult);
}

// Bind the datagrid.
dlResults.DataSource = dtResults;
dlResults.DataBind();
pnlResults.Visible = true;
In addition to the functionality shown above, the example project includes simplistic code that displays next and previous paging links at the bottom of the page. This lets the user navigate back and forth between the first five results and the second five results of the first ten results.
Just the Tip of the Iceberg
Hopefully this article has opened your eyes to the possibilities available for performing powerful Web searches using the Google Web service. The example project illustrates the basics of a straightforward search solution. However, the possibilities are quite broad. You could easily wrap up the entire search capabilities illustrated here into a Web User Control and use it in a small section of a page. You could perform searches using virtually any control event on an ASP.NET page including clicking linkbuttons and making a selection from a listbox.