XML Web Services

In this section we will build a more interesting Web service that returns a ADO .NET DataSet, containing the full set of records from a table. We will create our own database table and access the data from the table with this Web service. To Start, open Microsoft Access and create a new Database named Currency. Create a new table Table1 and add three columns named, Country Code, Country Name and Currency. Enter some values in the table and close it. Open Visual Studio .NET and select ASP .NET Web service from the projects type template. Drag a OleDb connection from the Data tab in the toolbox and using the properties window build a connection string that connects to the Currency database which we created. Switch to the code view and start writing the following code.

Imports System Imports System.Web.Services Imports System.Data.OleDb ‘import this namespace as we are working with an OleDb source<WebService(Namespace := “http://tempuri.org/&#8221;)> _Public Class Service1 Inherits System.Web.Services.WebService #Region ” Web Services Designer Generated Code ” #End Region <WebMethod()> Public Function GetData() As DataSet ‘WebMethod name is GetData,generate data set Dim da as OleDbDataAdapter=new OleDbDataAdapter(“Select * From Table1”,_ OleDbConnection1) ‘dataadapter Dim ds As DataSet=new DataSet() ‘declaring a new DataSet da.Fill(ds, “Table1”) ‘filling dataadapter Return ds ‘returning dataset End Function End Class

Consuming the Service

Once you finish with coding the Web service we need to consume this service. To do that, open a new Windows Application and from the toolbox drag a DataGrid and a Button. Our intention here is to load the data from Table1 in the Currency database into the DataGrid when we click the Button. Now, add a Web reference to the Web service by selecting Reference->Add WebReference in the Solution Explorer Window. Enter the URL of the service in the address bar and click “Add Reference“. That adds a reference to the Web Service. Now double-click on the Button and write the following code.

Public Class Form1Inherits System.Windows.Forms.Form #Region ” Windows Form Designer generated code ” #End Region Private Sub Button1_Click(ByVal sender As System.Object, ByVal e_ As System.EventArgs)Handles Button1.Click Dim myService As New localhost.Service1() ‘an instance of the Web service Dim ds1 As DataSet = myService.GetData DataGrid1.DataSource = ds1.Tables(“Table1”) ‘filling the datagrid with table End Sub End Class

Once you finish with the code, run the Windows Application and click on the Button. The data you entered in Table1 of the Currency database will be displayed in the datagrid. The difference, we are accessing the data with a Web service. The image below displays that.

Creating a Web service with VB.NET

Web services technology is based on HTTP, Simple Object Access Protocol (SOAP), and XML. Since Web services use open standards, calling Web services is fairly simple.

VB.NET allows you to use Web services as if they were entirely local objects since most of the marshaling between the client and the server is taking place in the background. This tip shows you how to create a simple Web service.

Example

I will create a Web service and add a Web function that will return the current machine’s IP address. Here are the steps for creating a Web service:

1. Open Visual Studio.Net and select Create New Website under VB.NET.
2. Select Web Service from the options listed.
3. Once you get the code window open, add the following code:

<WebMethod()> _
        Public Function GetMachineIPAddress() As String         

         Dim strHostName As String = ""
         Dim strIPAddress As String = ""
         Dim host As System.Net.IPHostEntry         

         strHostName = System.Net.Dns.GetHostName()
         strIPAddress = System.Net.Dns.GetHostEntry(strHostName).HostName.ToString()         

         host = System.Net.Dns.GetHostEntry(strHostName)
         Dim ip As System.Net.IPAddress
         For Each ip In host.AddressList
             Return ip.ToString()
         Next         

         Return ""         

     End Function

Once you debug the example, you will see a screen that looks like Figure A.

Figure A

It will list two available Web methods: the one that was generated (HelloWorld) and the one I created (GetMachineIPAddress). Click the link for GetMachineIPAddress, and you will see a screen allowing you to get more information about this method and invoking it (Figure B).

Figure B

Click the Invoke button, and the result will look like Figure C.
Figure C

ASP.NET Screen Scraping

ASP.NET and the .NET framework make it unbelievably easy to retrieve web content (that’s it, whole web pages) from remote servers. You might have various reasons to retrieve remote web content, for example you might want to get the latest news headlines from popular news sites and link to them from your website.

To accomplish screen scraping in classic ASP, we had to resort to COM objects like AspHttp, ASPTear and Microsoft.XMLHTTP. The good news is that the .NET framework has built-in classes allowing getting remote web content with ease.

We are going to use 2 .NET classes found in the System.Net namespace – WebRequest and WebResponse, to get the remote web page content.

Here is how ASP.NET screen scraping works. We need to create an instance of the WebRequest class and request a web page through it. We can request either a static page (.htm, .html, .txt, etc.) or dynamic page (.asp, .aspx, .php, .pl, etc.). The type of the page we are requesting it’s not important, because we are getting what the page displays in the browser (usually HTML), not the actual page code.

After we have requested the page with our WebRequest object, we’ll have to use the WebResponse class in order to get the web page response returned by the WebRequest object.

Once we get the response into our WebResponse object, we use the System.IO.Stream (this class provides a generic view of a sequence of bytes) and System.IO.StreamReader classes to read the web page response as a text. The StreamReader class is designed to read characters from a byte stream in a particular encoding, while the Stream class is designed for byte input and output.

In our example below, we just print the response in the browser window with Response.Write, but you can parse this content and use only the parts that you need.

Here is a full working example of ASP.NET screen scraping, written in ASP.NET (VB.NET):

<%@ Import Namespace=”System” %>
<%@ Import Namespace=”System.Net” %>
<%@ Import Namespace=”System.IO” %>

<script language=”VB” runat=”server”>

Sub Page_Load(Sender as Object, E as EventArgs)

Dim oRequest As WebRequest = WebRequest.Create(“http://www.aspdev.org/asp.net/&#8221;)
Dim oResponse As WebResponse = oRequest.GetResponse()

Dim oStream As Stream = oResponse.GetResponseStream()

Dim oStreamReader As New StreamReader(oStream, Encoding.UTF8)

Response.Write(oStreamReader.ReadToEnd())
oResponse.Close()
oStreamReader.Close()

End Sub

</script>

Cloud Computing

Cloud computing is a general term for anything that involves delivering hosted services over the Internet. These services are broadly divided into three categories: Infrastructure-as-a-Service (IaaS), Platform-as-a-Service (PaaS) and Software-as-a-Service (SaaS). The name cloud computing was inspired by the cloud symbol that’s often used to represent the Internet in flowcharts and diagrams.

A cloud service has three distinct characteristics that differentiate it from traditional hosting. It is sold on demand, typically by the minute or the hour; it is elastic — a user can have as much or as little of a service as they want at any given time; and the service is fully managed by the provider (the consumer needs nothing but a personal computer and Internet access). Significant innovations in virtualization and distributed computing, as well as improved access to high-speed Internet and a weak economy, have accelerated interest in cloud computing.

A cloud can be private or public. A public cloud sells services to anyone on the Internet. (Currently, Amazon Web Services is the largest public cloud provider.) A private cloud is a proprietary network or a data center that supplies hosted services to a limited number of people. When a service provider uses public cloud resources to create their private cloud, the result is called a virtual private cloud. Private or public, the goal of cloud computing is to provide easy, scalable access to computing resources and IT services.

Infrastructure-as-a-Service like Amazon Web Services provides virtual server instanceAPI) to start, stop, access and configure their virtual servers and storage. In the enterprise, cloud computing allows a company to pay for only as much capacity as is needed, and bring more online as soon as required. Because this pay-for-what-you-use model resembles the way electricity, fuel and water are consumed, it’s sometimes referred to as utility computing.

Platform-as-a-service in the cloud is defined as a set of software and product development tools hosted on the provider’s infrastructure. Developers create applications on the provider’s platform over the Internet. PaaS providers may use APIs, website portals orgateway software installed on the customer’s computer. Force.com, (an outgrowth of Salesforce.com) and GoogleApps are examples of PaaS. Developers need to know that currently, there are not standards for interoperability or data portability in the cloud. Some providers will not allow software created by their customers to be moved off the provider’s platform.

In the software-as-a-service cloud model, the vendor supplies the hardware infrastructure, the software product and interacts with the user through a front-end portal. SaaS is a very broad market. Services can be anything from Web-based email to inventory control and database processing. Because the service provider hosts both the application and the data, the end user is free to use the service from anywhere.

Web design layout tutorial

Create a new document 800×800 with a black background, select the color #01afee and create a rectangle. Once you have your rectangle press “CTRL + T”, now rotate your rectangle like this.

Now for this part you need some “splatter brushes” EITHER search yahoo or goto a site like brusheasy and download a set, once you have them make some randam splatters over your canvas, using the colors blue and black.

Select the type tool and add your site title and slogan.

Now if you have used two colors like mine above for your title then select one of the colors and add a splatter. If you have used white then you can just use a white splatter, you should have something like this.

Select the type tool again and add your navigation, use free transform (CTRL + T) to rotate the text.