METHODS in visual basic

Deploy pdf417 in visual basic METHODS

Note The using statement is different than the using directives. The using directives are covered in

these changes. The same techniques are employed by people writing OS-portable applications such as the Oracle kernel developers.

the client). This approach allows you to call remote methods just like local methods within your application. The code in Listing 6-31 shows the reusable CheckFaultResponse method that allows you check if a response is a fault response. This method throws an exception if a fault occurred. The exception message contains the fault reason, detail, and the exception type indicated in the subcode. You need to call the CheckFaultResponse method and pass the response to it right after you receive the DpwsSoapResponse response from the SendRequest method of the DpwsHttpClient class. Listing 6-31. A Reusable Method to Check a Response for Faults private void CheckFaultResponse(DpwsSoapResponse response) { if (response == null) throw new Exception("Response was null."); // Check for fault message if (response.Header.Action == "http://schemas.xmlsoap.org/ws/2004/08/addressing/fault") { // Parse fault message response.Reader.ReadStartElement("Fault", WsWellKnownUri.WsaNamespaceUri); response.Reader.ReadStartElement("Code", WsWellKnownUri.WsaNamespaceUri); string code = response.Reader.ReadElementString("Value", WsWellKnownUri.WsaNamespaceUri); response.Reader.ReadStartElement("Subcode", WsWellKnownUri.WsaNamespaceUri); string subcode = response.Reader.ReadElementString("Value", WsWellKnownUri.WsaNamespaceUri); response.Reader.ReadEndElement(); response.Reader.ReadEndElement(); response.Reader.ReadStartElement("Reason", WsWellKnownUri.WsaNamespaceUri); string reason = response.Reader.ReadElementString("Text", WsWellKnownUri.WsaNamespaceUri); response.Reader.ReadEndElement(); string detail = response.Reader.ReadElementString("Detail", WsWellKnownUri.WsdpNamespaceUri); Debug.Print("Fault response received:"); Debug.Print("Code: " + code); Debug.Print("Subcode: " + subcode); Debug.Print("Reason: " + reason); Debug.Print("Detail: " + detail); string exceptionMessage = reason + "\n" + detail + "\nCode: " + code + "\nSubcode: " + subcode;

The service receives the SOAP message and checks the security token type. Once the service determines that an X.509 certificate was used, it decrypts the message signature using the public key. This process allows the services to retrieve the original message hash. If the decryption process fails, then the service assumes that the client is not the original sender of the message, or the message has been tampered with, and a SOAP exception is raised. The service then generates its own message digest using the same algorithm that the client used. The service compares its generated message digest against the one that has been obtained from the client. If the two message digests match, then the signature has passed verification. If it does not, then the service assumes that the message has been tampered with, and a SOAP exception is raised.

Notice that I have to call the AsEnumerable() extension method on the DataTable object. This converts the DataTable into a strongly typed collection of DataRow objects, which is a suitable data source for a LINQ query. Inside the query, I project only those DataRow objects whose value for the City field is London. In essence, I have used LINQ to further filter the data I got back from the database. I then create a second LINQ query using the same DataTable as the data source. I am able to do this without making a second SQL query because the DataSet is an in-memory cache of result data from the database. The query I perform projects an anonymous type that contains the FirstName and LastName fields of the DataRow objects in the DataTable whose value for the Title field is Sales Representative. I enumerate the results from both queries, and compiling and running Listing 31-7 produces the following output: City Result: Steven Buchanan City Result: Michael Suyama City Result: Robert King City Result: Anne Dodsworth Title Result: Nancy Davolio Title Result: Janet Leverling Title Result: Margaret Peacock Title Result: Michael Suyama Title Result: Robert King Title Result: Anne Dodsworth Press enter to finish It is important to realize that when you use LINQ to query a DataSet, you are only querying the data that was returned from the SQL query used to populate it. Unlike the Entity Framework, a LINQ to DataSet query won t query the database for additional data. If you populated a DataSet for rows in the Employees table that have a City value of London, using LINQ to query for rows that have a value of Seattle won t return any results, even though there are such rows in the database.

Streams support IO operations using either System::Byte (or the native equivalent type name, unsigned char) or a managed array of System::Byte. As an example, the whole contents of FileStream can be written into a byte array: array<Byte>^ bytes = gcnew array<Byte>(bytesInFile); // write whole file contents into bytes, starting from position 0 fs->Read(bytes, 0, bytesInFile); To get a string from the byte array, it is necessary to know how the file s text is encoded into bytes. The FCL provides different encoder implementations. If simple ASCII encoding can be assumed, the following code provides an easy decoding: String^ textInFile = Encoding::ASCII->GetString(bytes);