HTML template files are made up of HTML tags, tag attributes, and text. HTML tags tell the system how to format and display the information on the page. Attributes provide additional detail about a specific item on the page. For example, for a picture in an HTML page, a tag called an IMG tag tells the system to format and display a picture. An attribute of that tag tells the system where to retrieve the picture from on the server.
When Visual Basic first adds a template to your webclass, it parses the file and lists all the tags for which one or more attributes can be treated as events. These attributes are not actual events, however, until they go through a process known as connecting. Prior to connection, it is more accurate to think of the tag attributes listed in the designer as event candidates.
You can connect an attribute in two ways:
For More Information See "Webclass Events" for more information on adding events to a webclass and the types of events a webclass can process. See "Responding to Events in IIS Applications" for more information on writing code to process your events.
The template events in a webclass generally correspond to attributes of HTML tags in the template file. For example, an image event corresponds to an attribute of the IMG tag in the HTML page, and a hyperlink event corresponds to an A tag attribute in the HTML page. However, the association between attributes and events is not automatic — you must connect to events those tag attributes that you want to treat as events.
Connecting an attribute to an event enables the webclass to launch an event procedure when the end user selects the HTML element the tag attribute represents. For example, suppose you are working with a template called FeedbackPage. When you add this template to the webclass, Visual Basic parses the file and discovers that there are two elements within it capable of submitting requests to the server: a Submit hyperlink and a Home hyperlink. It lists the tags and attributes for these two elements in the designer's Detail panel. You can connect the attributes to events if you want them to fire events in your application.
Only connected events can be programmed. That is, after you connect an event, it appears in the Procedure drop-down list in the Code Editor window, and you can write procedures for it. Disconnected events do not appear in this list.
The Webclass Designer indicates the events that have not been connected in two ways:
After you connect an attribute to an event, you can either write code for it in the Code Editor window, rename the event to which it is connected, or disconnect it. You might disconnect an event if you want to connect it to a webitem instead of to an event, or if you do not want it to function as an event. See "Connecting Attributes to a Custom WebItem" below for information on connecting to a webitem rather than an event.
To connect an attribute to an event
Visual Basic changes the text in the Target column to indicate that the attribute has been connected, and it displays the event in the tree view beneath the appropriate template.
To disconnect an attribute from an event
When you connect an attribute to a webitem rather than an event, you tell the webclass to activate that webitem when the HTML element the tag attribute represents is selected in the browser. When Visual Basic activates the webitem, it fires the webitem's Respond event. You must choose the specific webitem to which you want to connect the attribute.
For example, you might connect the attributes from a template file's IMG tag to a custom webitem that references an image stored on the server. When the user selects the element corresponding to the tag, it makes a call to the server that the webclass intercepts. The webclass tells Visual Basic to launch the associated webitem and fire its Respond event, which in turn retrieves the image from the database and returns it to the browser.
Visual Basic indicates that an attribute has been connected to a webitem in the Target column. Before you connect an attribute to a webitem, the word <None> appears in the Target column. After connection, the Target column displays the name of the webitem to which you connected the tag.
After you connect an attribute to a webitem, you can disconnect it and either leave it disconnected or connect it to another webitem. See "Connecting Attributes to Events" for more information on connecting to events.
To connect an attribute to a webitem
Visual Basic displays the name of the webitem to which the attribute has been connected in the Target column.
To disconnect an attribute from a webitem