Programming Tutorials

By: Steven Holzner : 2009-02-24

Description: A dataset is a cache of data retrieved from a database, and, as we know, it's the major component of ADO.NET. A DataSet object is made up of a collection of DataTable objects that you can relate to each other using DataRelation objects. You also can guarantee data integrity with the UniqueConstraint and ForeignKeyConstraint objects.

By: Steven Holzner : 2009-02-24

Description: DataTable objects store data tables, and as such, they're central to datasets and data views (for more on data views, see "Using Data Views" in Chapter 20). In code, you create data tables and then add the fields in each row to them. For example, here's how I create a new table named Table1 in the DataTableCode example on the CD-ROM that we'll see in the "Creating a Data Table in Code" topic in this chapter. Note that after creating the table, I create a new DataColumn object, configure it, and add it to the table's Columns collection

By: Steven Holzner : 2009-02-24

Description: DataRow objects represent rows in a DataTable object. You use DataRow objects to get access to, insert, delete, and update the records in a table.

By: Issac : 2009-02-22

Description: Multithreaded Socket Programming is the basic idea behind a TCP Chat Server communication. A Multithreaded Server Socket Program communicates with more than one Client at the same time. But there the communication is happening only between Server to Client or Client to Server, there is no communication between Client to Client. In a Multithreaded Chat Server, a Client can communicate with any number of Clients, currently connected on the Chat Server.

By: Issac : 2009-02-22

Description: Chat server keeps listening to PORT 8888 for any request from clients, once a request is received it adds the name of the client into a client list maintained (in this code it is a Hash table) and then creates a new thread for communication with server. When the Server gets a message from a client, it selects all the Clients from clientsList and sends the message to all Clients (ie we can say Broadcast) in the clientsList. So each Client can see the message each other and they can communicate through Chat Server.

By: Issac : 2009-02-21

Description: When we want to read content of an HTML page from a remote webserver, in vb.net we are using WebRequest, WebResponse. WebResponse return a StreamReader and we can get the content from StreamReader.

By: Issac : 2009-02-21

Description: The Chat Client here is to connect the PORT 8888 of the Chat Server in "127.0.0.1 ". Here we have given "127.0.0.1", because Chat Server and Chat Client are running on the same machine. When we start the Chat Client program, we have to enter a User Name just for identifying in Server. The Client program connect to the Chat Server and starts a Thread for receiving the messages from client, Here we implement an infinite loop in the function getMessage () and call this function in a Thread.

By: Issac : 2009-02-21

Description: Since XML is a self describing language it specifies data and rules through which we can extract what data it contains, Reading an XML file means that we are reading the information embedded in XML tags in an XML file.

By: Issac : 2009-02-21

Description: XML is a platform independent language, so if we create an XML file in one platform it can be used in other platforms also.For creating a new XML file in VB.NET, we are using XmlTextWriter class. The class takes FileName and Encoding as arguments. Also we are here passing formating details. The following source code creating an XML file product.xml and add four rows in the file.

By: Issac : 2009-02-21

Description: XML – Extended Markup Language, which is a subset of SGML (Standard Generalized Markup Language) is a tag based language which is very apt in handling data across applications, also it is a platform independent language that is, information formatted in XML can be used in various Operating Systems, also it is a self describing language so it provides the data and rules which can be used to identify the information it contains.