URL ACCESS IN ACTION in Visual Basic .NET

Maker ECC200 in Visual Basic .NET URL ACCESS IN ACTION

To demonstrate how both a WinForm-based report consumer and a Web-based report consumer can leverage the URL access option to request reports, let s look at a couple of sample applications from the source code available with this book.

URL Access with WinForms: AccessOptions The code sample for this section can be launched from the chapter 10 menu in the AWReporterWin project. This one-form sample application actually uses both access options (URL and SOAP), but for the purposes of our discussion in this section, we describe only the URL access option. We cover the SOAP access methods that this sample code uses later in section 10.5. This code sample demonstrates two possible implementation approaches to integrate a WinForm-based report consumer with Reporting Services by URL: Using the Microsoft WebBrowser ActiveX control Shelling out to the browser We kept the code simple on purpose. For now, the design goals for the AccessOptions application are to show you the minimum steps needed to access reports using the URL access option. Figure 10.4 shows the AccessOptions form. To run a report by URL, the user has to specify the Report Server URL, the report path, and the export format. In the case of parameterized reports, the user must also enter all parameters (name and value) in the Parameters grid, that do not have default values specified.

Figure 10.4 The AccessOptions application demonstrates how a WinForm application can request reports via URL or the RS Web service (SOAP).

Let s first see how this code sample integrates with the Report Server by URL. Then in section 10.5 you ll learn how to do this by using the RS Web service. Using the Microsoft WebBrowser ActiveX control To request reports by URL, a WinForm application can leverage the Microsoft Web Browser ActiveX control to embed the report inside a form. One possibility where embedding the report can be useful is when your requirements call for implementing a Report Search form. Once the user selects a report, you may want to display the report inside the search form instead of navigating to a new form. If you haven t used the Microsoft WebBrowser control in the past, you will be happy to find that it allows you to add browsing, document viewing, and data downloading capabilities to your applications. Because the WebBrowser control is COMbased, this approach is also suitable for classic Windows-based applications, for example, Visual Basic 6 clients. The WebBrowser control is found in the Common Controls section of the Windows Application Project toolbox in Visual Studio 2005. If you need more information about this control, check the Resources section at the end of this book. Loading the export formats When the AccessOptions form is loaded, the Format drop-down is populated with the rendering formats that the Report Server supports. Rather than hardcoding the drop-down items, the AccessOptions application calls the ListExtensions method of the RS Web service. Although the method call incurs a performance hit, the advantage of not hardcoding the list is flexibility, because you don t have to redistribute the application if new rendering extensions have been added. Listing 10.1 shows how the LoadFormats function calls ListExtensions.

private void LoadFormats() { Calls the ReportingService2005 rs = RsHelpers.Proxy; ListExtensions API Extension[] extensions = null; extensions = rs.ListExtensions(ExtensionTypeEnum.Render); foreach (Extension extension in extensions) { if (extension.Name.ToLower()!="null") cmbFormat.Items.Add(extension.Name); } cmbFormat.SelectedText = "HTML4.0"; }

Because this method is executed when the form loads, be sure to update the Report Server URL, which defaults to localhost, before running the sample. The ListExtension method returns an array of all supported rendering extensions as specified in the RSReportServer.config file. Each rendering extension is exposed as of type Extension. Note that the code specifically ignores the NULL rendering extension b. This extension is not a rendering extension per se because it doesn t render reports in any specific format. Instead, it is useful for prepopulating the report session cache for subscribed report delivery, as we explain in more detail in chapter 12. Because this is a dummy extension and cannot be used for report rendering, we skip it. For the sake of simplicity, we don t retrieve the list of report parameters from the RS Web service, nor do we validate the parameters in any way. For the purposes of this example, the user is responsible for setting up the parameters correctly. To show the parameters in the grid, we use a typed dataset, EntityParameter, which we bind to the grid. Requesting the report Once the user has filled in the report parameters (if any), we are ready to request the report by calling the RunByURL function, whose abbreviated code is shown in listing 10.2.

Listing 10.2 The Microsoft WebBrowser control, which WinForm clients can use to place the report inside a form

private void RunByURL() Constructs the { report URL StringBuilder urlBuilder = new StringBuilder(); urlBuilder.Append(txtServer.Text); urlBuilder.Append (" "); Appends the report urlBuilder.Append (txtReportPath.Text); parameters EntityParameter.ParametersDataTable table = EntityParameter.ParametersDataTable)grdParams.DataSource; foreach (EntityParameter.ParametersRow row in table.Rows){ urlBuilder.Append (String.Format("&{0}={1}", row.Name, row.Value)); } urlBuilder.Append (@"&rs:Format=" + cmbFormat.Text); urlBuilder.Append (@"&rs:Command=Render"); ReportBrowser reportBrowser = new ReportBrowser(); reportBrowser.RenderReport(urlBuilder.ToString()); reportBrowser.Show(); }