Tài liệu Programming Microsoft SQL Server 2000 with Microsoft Visual Basic .Net - P12 ppt

Form 2 reappears after the user replies to the prompt, the form shows the first two text boxes with their prior values as well as the fourth text box for displaying a column value. The specific value in the bottom text box is the one matching row specified by the user’s reply to the prompt. Figu re 1 3 - 1 1 . The client applicat ion form for the Service1 W eb service in the Tab leProcessor folde r. The processing of the return values from the ColumnValues Web method illustrates a typical scenario. A developer engineers an application so that it can accommodate any of several scenarios. For example, a client application makes a selection from the total set of column values to show the column value for just one row instead of the whole set of column values as in Figure 13-10. Figure 13-12 tracks the process from designating database and table names to capturing the reply to the I nputBox prompt to showing the specific column value that a user wants to view. I n the top window, the user designates that they want results from the Custom ers table in the Northwind database before clicking the button labeled Get Column Value. The m iddle window shows the user indicated that the application should show the column value for the fifth row. By the way, the prompt adjusts automatically to show the maximum number of rows. The application does this by running the RowCount Web method when processing a request to show a specific row value from the first column. The bottom window in the figure reveals BERGS as the column value for the fifth row in the first column. You can easily confirm this outcome for yourself by examining the output in Figure 13-10, which shows all the column values for the first column in the Custom ers table from the Northwind database. Figu re 1 3 - 1 2 . The client applicat ion for t he Se rvice1 W eb service in the TablePr ocessor folder dem on stra t ing h ow it handles a request t o show a par t icular colum n va lu e from the first colum n of the Cu stom ers t able in the Northw ind dat aba se. The following listing shows the code behind Form 2 that manages the behavior of the client application for the Web service in the TableProcessor folder. The listing starts with the instantiation of a module-level variable, x ws1, for the proxy Web service. Notice how Visual Basic .NET systematically names the second-level reference in the proxy object. The proxy for the first Web service uses localhost as its second name. The proxy for the deployed version used localhost1 as its second name. This proxy variable, which is the third one in the chapter, has localhost2 as its second name. In all three cases, the first name for a proxy denotes the client application’s project— namely, XMLWebServiceClients. Also, the name for the proxy object in each case refers to the .asmx file in the Web service, which has the name Service1 in all three instances. The body of the listing includes three event procedures. One is a form Load event procedure. This event procedure merely readies the initial look of the form. In particular, it makes the third and fourth text boxes, along with their matching labels, invisible. The application also includes a Click event procedure for each button on the form. These event procedures invoke the RowCount and Colum nValues Web methods as well as processing their return values. As you can see, the xws1 proxy variable appears in both Click event procedures, which is why the listing starts by instantiating the variable at the module level. The But ton1_Click event procedure invokes the RowCount Web method and displays its result in TextBox3. This procedure actually starts by m aking sure Text Box4 and its matching label are invisible. These two controls are for displaying a column value and labeling the return value, but a click of the Row Count button (Butt on1) doesn’t show any column values. Next the procedure copies the Text property values of TextBox1 and TextBox2 to memory variables in the client application. These variables store the name of the database and the table for the Web service to examine. After saving the local m emory variables, the procedure uses them as arguments while invoking the RowCount Web method. The arguments specify for which table in which database to return a row count. The final group of lines in the event procedure makes the text box and label (TextBox3 and Label3) for the row count value visible on the form. The procedure’s final line passes the converted value type of the return value from the RowCount Web method to the Text property of TextBox3. The Click event procedure for Butt on2 is slightly more sophisticated than the one for Button1. There are three reasons for this. First, the Button2_Click event procedure invokes two Web methods instead of one. Second, the Click event procedure for Button2 presents a prompt to gather user feedback. Third, the event procedure stores the return value from the Colum nValues Web method as an array and then uses the reply to the prompt to pick a value from the array and display it on the form. Like the event procedure for Butt on1, the Butt on2_Click event procedure starts by making a text box and label invisible. I n this case, the text box and label are for the RowCount Web method’s return value, which a click to Button2 doesn’t show. Just because the procedure doesn’t directly show the return value from the RowCount Web method doesn’t mean the Web method is unused in the procedure. On the contrary, the RowCount Web method’s return value is used early and often throughout the procedure. In fact, the next three lines save arguments for the Web method, invoke it, and save the return value in a memory variable, m yRowCount. Next the procedure prom pts the user for which row in the first column to show a column value. The procedure uses an I nput Box function for this with the default value 1. After obtaining a reply to the I nput Box function prompt, the procedure concludes its data input phase from the user. All the data it needs is in memory or available via a Web method call. Next the procedure invokes the Colum nValues Web method and saves its result as a string. Then the procedure strips off the leading string ( "Values in column 1 are: " ) from the return value and saves the resulting string (st r1). This leaves str1 with just the column values from the table named in TextBox2. Perhaps the most interesting aspect of the procedure is the parsing of str1 to extract individual column values that go into cells in the m yVect or array. The array is dimensioned based on the row count from the table named in Text Box2. This value is available via a memory variable (m yRowCount) from the invocation of the RowCount Web method. The procedure then opens a loop that iterates through the column values in str1. On each pass through the loop, the code reads the first column value in str1, which is a substring up to but not including the first comm a. It then saves this value in the first em pty cell in the myVector array and removes the value, its trailing comma, and the blank space after the comma from the str1 variable. Therefore, successive passes always have a fresh value as the first column value in str1. The procedure concludes by m aking TextBox4 with its matching label visible and by selecting a cell from the m yVect or array to show based on the user’s response to the I nputBox function prompt. ’Use cabinc_NthRoot Web Service. Dim xws1 As New XMLWebServiceClients.localhost2.Service1( ) Private Sub Form2_Load(ByVal sender As System.Object, _ ByVal e As System.EventArgs) Handles MyBase.Load ’Hide RowCount text box and label. TextBox3.Visible = False Label3.Visible = False ’Hide ColumnValue text box and label. TextBox4.Visible = False Label4.Visible = False End Sub Private Sub Button1_Click(ByVal sender As System.Object, _ ByVal e As System.EventArgs) Handles Button1.Click ’Hide ColumnValue text box and label. Label4.Visible = False TextBox4.Visible = False ’Pass database name and table name from text boxes on ’the form to the RowCount Web method. Dim adbname As String = TextBox1.Text Dim atablename As String = TextBox2.Text Dim myRowCount As Integer = _ xws1.RowCount(adbname, atablename) ’Make the RowCount label and text box visible ’before populating the text box with a value ’from the RowCount Web method. Label3.Visible = True TextBox3.Visible = True TextBox3.Text = myRowCount.ToString End Sub Private Sub Button2_Click(ByVal sender As System.Object, _ ByVal e As System.EventArgs) Handles Button2.Click ’Hide RowCount text box and label. Label3.Visible = False TextBox3.Visible = False ’Pass database name and table name from text boxes on ’the form to the RowCount Web method. Dim adbname As String = TextBox1.Text Dim atablename As String = TextBox2.Text Dim myRowCount As Integer = _ xws1.RowCount(adbname, atablename) ’Print out the maximum number of rows as part of a pr ompt ’for a selected row from a user. Dim strInputMsg = _ "What row to max. of " & myRowCount.ToString & "? " Dim intReturnedRow As Integer = _ CInt(InputBox(strInputMsg, "", "1")) ’Pass database name and table name memory values to t he ’ColumnValues Web method and strip off leading string ’for column values. Dim myColumnValues As String = _ xws1.ColumnValues(adbname, atablename) Dim intToColon = InStr(myColumnValues, ":") Dim str1 = Mid(myColumnValues, intToColon + 2, _ Len(myColumnValues)) ’Dimension array and integer variable for loop. Dim myVector(myRowCount - 1) As String Dim intRow As Integer ’Pass string of column values to an array. For intRow = 0 To myRowCount - 1 myVector(intRow) = _ str1.substring(0, InStr(str1, ",") - 1) str1 = Mid(str1, InStr(str1, ",") + 2, Len(str1)) Next ’Make ColumnValue label and text box visible before ’passing array value corresponding to user selection in ’the text box. Label4.Visible = True TextBox4.Visible = True TextBox4.Text = myVector(intReturnedRow - 1) End Sub The SQL Se rver 2 0 0 0 W eb Ser vices Toolk it The Web Services Toolkit simplifies the creation of Web services based on SQL Server 2000 database objects and templates in IIS virtual directories. Microsoft built on an earlier approach for delivering XML functionality from SQL Server with the Web Services Toolkit— namely, by extending the capability of the IIS virtual directory so that it can host a Web service. The Web service from an IIS virtual directory exposes individual database objects and templates as Web m ethods. After the creation of a Web service based on an IIS virtual directory, you still use the same basic approach demonstrated in the preceding two sections for developing a client application for your Web service. This section starts by revealing how to design an IIS virtual directory to offer a Web service. The design of the virtual directory specifies the Web service based on a stored procedure. The review of a core client application and a simple extension of it equip you with the skills to build your own solutions for capturing XML fragm ents returned from Web methods based on database objects and templates. Scripting a SQL Se r ver User for a Virt ual Direct ory Although it isn’t essential to designate a SQL Server user when specifying an II S virtual directory, it can be useful— especially when the virtual directory hosts a Web service. Any Web service emanating from an IIS virtual directory can have a potentially large number of users. By using a special SQL Server user, you can set the permissions for the special SQL Server user and be sure that anyone who connects to the Web service will have permission to perform the tasks enabled through the exposed Web methods. You can also limit the ability to perform tasks through the Web service by lim iting the permission for its special SQL Server user. N ote The .NET Framework contains standard security conventions, including techniques for managing the use of encryption that your applications m ay require for protecting a user’s identity, managing data during transm ission, and authenticating data from designated clients. See the “Cryptography Overview” topic in the Visual Studio .NET documentation for more detail on this topic. This topic is a major section within the “Security Applications” topic, which you might also want to review. The following T-SQL script is meant for you to run from Query Analyzer for the SQL Server 2000 instance that you use for the remaining samples throughout this chapter. The script is available among the book’s sample files as ScriptsFor13.sql. The sample is built around the notion that this is the local SQL Server 2000 instance. If this isn’t the case, you’ll need to adjust the sample accordingly. The script drops any prior SQL Server login for the connected SQL Server instance and a prior user for the Northwind database named vbdotnet1. If you incur error messages because the user doesn’t exist, simply ignore them because the purpose of the script is to remove a login or user only if it does exist. After making sure vbdotnet1 is free for assignment, the script adds a new user named vbdotnet1 and grants access to the Northwind database. Recall that the Northwind database is one of the SQL Server sample databases. The database’s public role grants any user access to m ost database objects that ship as part of the database. For exam ple, vbdotnet1 has automatic permission to run all stored procedures, such as the Ten Most Expensive Products stored procedure, which is one of the built-in user-defined stored procedures for the database. Notice that this script uses “/ * ” to mark the beginning of the code com m ent that stretches over multiple lines, and “* / ” to end it. /*Run from member of sysadmin fixed server role. Ignore errors if user does not already exist. */ USE Northwind EXEC sp_revokedbaccess ’vbdotnet1’ EXEC sp_droplogin @loginame = ’vbdotnet1’ GO Add vbdotnet1 user with known permissions. EXEC sp_addlogin @loginame = ’vbdotnet1’, @passwd = ’passvbdotnet1’, @defdb = ’Northwind’ EXEC sp_grantdbaccess ’vbdotnet1’ GO Building a W eb Service in an I I S Virt ua l D irectory Now that we have a SQL Server user, we can proceed through the steps for creating an IIS virtual directory. This directory will contain the contract for a Web service. You can create a new IIS virtual directory by choosing Programs from the Windows Start menu, then SQLXML 3.0, and then Configure IIS Support. This opens the IIS Virtual Directory Management utility for SQLXML 3.0. In order to open the utility, you must, of course, have already installed Web Release 3 (SQLXML 3.0). See the “Web Services from the Web Services Toolkit” section for a URL to download Web Release 3 along with the Web Services Toolkit. With the IIS Virtual Directory Management utility open, expand the folder for the local Web server. Then right-click Default Web Site within the local Web server, choose New, and then choose Virtual Directory. This opens a multi-tabbed dialog box that lets you set the properties of a new virtual directory. You can use the New Virtual Directory Properties dialog box to create the virtual directory by following these instructions: 1. On the General tab, name the directory Chapter13, and give the virtual directory the path c: \ inetpub\ wwwroot\ Chapter13. You can type the path or use the Browse button to navigate to the folder. Although the utility allows you to create a new folder from within the utility, som e may find it easier to create the folder before opening the utility. 2. On the Security tab, select the SQL Server radio button. Then enter vbdotnet1 in the User Name text box and passvbdotnet1 in the Password text box. Confirm the password before moving off the tab. 3. On the Data Source tab, accept the default settings of the local SQL Server and default database for the current login. 4. On the Settings tab, leave Allow Template Queries selected and also select Allow POST. 5. On the Virtual Names tab, you set up the virtual directory through which you can deliver Web services. With < New virtual name> highlighted in the Defined Virtual Names list box, enter SoapFor13 in the Name text box. Then select soap from the Type list. Next, in the Path text box, enter the path for your virtual directory, namely c: \ inetput\ wwwroot\ Chapter13. Finally click Save to enable the configuration of your Web service associated with the SoapFor13 virtual name. Once you’ve clicked Save, the Configure button is enabled. 6. While still in the Virtual Names tab, click Configure (see Figure 13-13) to select SQL Server stored procedures and user- defined functions to expose as Web methods. You can also expose templates through the Web service. Although your database objects and templates m ust exist before you can expose them, the Web Services Toolkit doesn’t expose them until you explicitly configure it to make the Web service offer Web methods based on a stored procedure, user-defined function, or template. Figu re 1 3 - 1 3 . The V irt ual Nam e t ab for t he New Virtual Dire ctory Proper t ie s dialog box for the SoapFor 1 3 W eb service in the Chapt er1 3 virt ual dir ect ory. 7. After you click Configure, the Soap Virtual Name Configuration dialog box opens so that you can specify items to expose as Web methods. If you are going to expose a stored procedure or a user-defined function, designate SP as the Type; otherwise, select Template to designate a template as the source for a Web method. You can designate an item by using the Browse button (…) to browse sources for a Web m ethod in the Web service hosted by the virtual directory. By clicking the Browse button with SP selected as the Type, I was able to pick Ten Most Expensive Products as the source for a Web method. I accepted the default selection to return the result set from the stored procedure as XML objects. With this selection, you can retrieve m ultiple results (or just one) from a stored procedure. Figure 13-14 shows the dialog box just before I click Save to expose the stored procedure as a Web method. 8. Click OK to save the configuration of the Web Service and close the Soap Virtual Name Configuration dialog box. [...]... specializing in Microsoft SQL Server, Micr osoft Access, and Web t echnologies He is a big fan of program m at ic solut ions, part icular ly t hose t hat involv e Visual Basic NET, ADO.NET, ASP.NET, XML Web ser vices, and T- SQL t echnologies he feat ures prom inent ly in t his book I f you look at som e of his prior book s, you’ll discov er t hat he also program s in VBA, ADO, Jet SQL, and SQL- DMO This... Vir ginia j oint ly run t heir pract ice, CAB, I nc ( ht t p: / / www cabinc.net ) Rick aim s his cont ent pr oduct ion at int er m ediat e and advanced SQL Server , Access, and Web dev eloper s Rick also writ es for leading com put er r esources, such as SQL Server Magazine, MSDN Online Libr ar y, Microsoft TechNet , Visual Basic Pr ogr am m er’s Jour nal, and Micr osoft I nt er act iv e Developer... ’strXML is string with XML to parse ’int1 is start position ’int2 - int1 calculates number of characters Dim TagValue As String = Mid(strXML, _ int1, int2 - int1) Return TagValue End Function Mor e on Popu la t in g Con t r ols w it h W eb Se r vices This sect ion drills deeper int o building Web serv ices wit h t he SQL Server 2000 Web Services Toolkit and client applicat ions w it h Visual St udio NET... SQL, and SQL- DMO This is Rick ’s four t h book in four y ear s Bot h t his book and a form er one t it led Pr ofessional SQL Serv er Developm ent wit h Access 2000 ( Wrox Pr ess I nc., 2000) focus heavily on t he developm ent of SQL Server solut ions While his ot her t wo books are on Microsoft Access, t hey dem onst rat e his com m it m ent t o Micr osoft dat abase t echnology All of t hese book s include... s The Response obj ect is t he m ost basic kind of obj ect in Visual St udio NET; t his t ype of obj ect can accom m odat e any ot her k ind of obj ect or t y pe Since t he Web serv ice can present eit her an XML docum ent or a SqlMessage obj ect , t he applicat ion needs Response obj ect s t o accom m odat e eit her out com e The SqlMessage obj ect can ret urn SQL Ser ver er ror m essages and warnings... result.OuterXml ’Iterate through column values in XML string ’within Web service method output Do While InStr(str1, "") > 0 str2 = MyTagValue("TenMostExpensiveProduc ts", str1) str2 = str2 & ", " & MyTagValue("UnitPric e", str1) ListBox1.Items.Add(str2) str1 = Microsoft. VisualBasic.Right(str1, _ Len(str1) (InStr(str1, "")) - _ Len("") + 1) Loop Case Else ’Handles... g a Clie n t Applica t ion t o Show a n XM L Fr a gm e n t Web services creat ed wit h t he SQL Server 2000 Web Serv ices Toolkit don’t have a built - in t est int er face I n addit ion, you connect t hem t o a client applicat ion slight ly differ ent ly t han Web serv ices, which y ou build direct ly wit h Visual St udio NET Nev er t heless, t he broad out line of t he t est ing pr ocess wit h a client... beginning and ending of t he XML fr agm ent ( < SQLXML> and < / SQLXML > ) Figu r e 1 3 - 1 5 Form 3 from t h e X M LW eb Se rvice Clie n t s p roj e ct sh ow in g t h e ou t pu t from t h e Ten _ M ost _ Exp e n sive _ Produ ct s W eb m e t h od in t h e Soap For 1 3 W e b ser vice Popu la t ing a List Box Cont r ol w it h a n X M L Se r vice Figure 1 3- 15 is int er est ing, but it ’s unlik ely t... illust rat es t he synt ax and procedur es for using param et er s wit h Web serv ices The following T- SQL list ing is t o be r un from Query Analy zer The list ing is available am ong t he book ’s sam ple files as Scr ipt sFor13 .sql I f you want , you can adapt t he sam ples for running direct ly from Visual St udio NET ( See Chapt er 11 for sam ples dem onst rat ing t his approach.) Howev er , it is... service method as a data set ba sed on ’CategoryID value in text box; notice returnvalue par ameter ’is not necessary with a SQL Server function procedur e Dim das1 As System.Data.DataSet das1 = _ xws1.udfProductsInACategoryAsDataset(CInt(TextBox 1.Text)) ’Populate second list box with product names ’for products in currently selected category in the ’first list box ListBox2.DataSource = das1.Tables(0) . deeper into building Web services with the SQL Server 2000 Web Services Toolkit and client applications with Visual Studio .NET. I n particular, the emphasis. starts with the instantiation of a module-level variable, x ws1, for the proxy Web service. Notice how Visual Basic .NET systematically names the second-level