Implementation of Web services
In order to achieve this example, we create a Web service called CategoriesService, select a visual C # ASP.NET web service as analog version of the project. Once the project is created, we add a method called AddCategories and add the following code to this method:
[WebMethod]
Public Bool Addcategories (String XML)
{
Try
{
Using (SqlConnection Conn = New SqlConnection ())
{
ValidateXML (XML))
{
XmLDocument Doc = New XmLDocument ();
Doc.loadxml (XML);
Conn.connectionstring =
"Server = localhost; uid = sa; pwd = thiru; database = northwind";
Cn.open ();
XMLNameSpaceManager nsmanager = new
XMLNameSpaceManager (Doc.nametable);
// add the namespace to the namespacemanager
nsmanager.addnamespace ("catns",
"http://tempuri.org/categoriesnamespace");
XMLNode CategoryNode =
Doc.documentelement.selectsinglenode ("Catns: category",
nsmanager);
String categoryName =
CategoryNode.selectsinglenode ("catns: categoryname",
nsmanager .innertext;
String categoryDescription =
CategoryNode.selectsinglenode ("catns: categoryDescription",
nsmanager .innertext;
SQLCommand command = new
SQLCommand ("USP_INSERTCATEGORIES", CONN);
Command.commandtype = commandtype.storedProcedure;
// add the category name parameter
Sqlparameter paramcategoryName = new
Sqlparameter ("@ categoryname", sqldbtype.nvarchar, 15);
ParamcategoryName.Direction = parameterDirection.input;
ParamcategoryName.Value = categoryName;
Command.Parameters.Add (paramcategoryName);
// Add the description parameter
SQLParameter Paramdescription = New
Sqlparameter ("@ description", sqldbtype.text);
Paramdescription.direction = parameterdirection.input;
Paramdescription.value = categoryDescription;
Command.Parameters.Add (paramdescription); Command.executenonQuery ();
}
Else
Throw
RaiseException ("AddCategories",
"http://tempuri.org/categoriesservice",
Builder.toString (),
"2000", "AddCategories", Faultcode.Client;
}
Return True;
}
Catch (SOAPEXCEPTION SOAPEX)
{
Throw SOAPEX;
}
Catch (Exception EX)
{
EventLog.WriteEntry ("Test", EX.MESSAGE);
Throw
RaiseException ("AddCategories",
"http://tempuri.org/categoriesservice" ,ex.message,
"1000", ex. Source, Faultcode.server;
}
}
As suggested, the AddCategories method is responsible for adding Category's details to the categories table of the Northwind database. Before performing the Add Action, the AddCategories method uses an external XML schema file to verify the added XML data. If the verification fails, it throws an exception to the client client.
Let's come to lector to browse the above code. First, pass the XML data to it, call the validateXML method. After a while, let's see the code of the validatexml method. ValidateXML method returns true or false, depending on whether the XML verification is successful. If you return true, then create an XMLDocument object instance and import XML data, and set the connectionString property to initialize the SQLConnection object, then call the Open method of the SQLConnection object. Second, create an XMLNamespaceManager instance, call the AddNameSpace method to associate a namespace. Once the namespace is associated, we can use the namespace identifier to reference the correct XML element. Again, create a SQLParameter object instance to add parameters to the stored procedure. Finally, call the EXECUTENONQUERY method of the SQLCommand object to perform the stored procedure.
If the ValidateXML method returns false, the SOAPEXCEPTION is thrown with the assistant method named raiseexception. Let's discuss RaiseException now. RaiseException method A basic assistant method, which is encapsulated to throw an exception code from the web service. The last parameter of the RaiseException method is an enumeration, which is defined as follows.
Public enum faultcode
{
Client = 0,
Server = 1
}
Xml
The verification failure indicates that the client provides invalid.
Xml
data. In this case, we should set the enumeration.
Client
, Indicate this error to the client application. This makes us notify the client application again to call again
Web
It is possible to check the format of the input data before the service. in case
Web
Services fails due to some other reasons (for example, the database server is not available), then set the enumeration
Server
. This incidates that
Web
Service failure is due to some of the problems of the server, the client application can reclaim after a few seconds. In fact, in catch
Capture in block
EXCEPTION
This is exactly what we have to do.
