4.1. Understand more details of the HTTP protocol
HTTP protocol is used to transfer resources between a client and a server.
HTTP is stateless.
HTTP is stateless.
The information is identified by URL (uniform resource locator).
URL structure: protocol://machine:port/context/resource
URL structure: protocol://machine:port/context/resource
Methods in HTTP
- HEAD : get metainfo contained in headers
- GET : get a resource from the server
- POST : send data included in the body to the server to be processed (get,add or update)
- PUT : send a resource(file) to the server by a new connection.
- DELETE: delete a resource
- TRACE : to obtain a response code from the server
- OPTIONS : to obtain http methods supported
- CONNECT : to transform connection to https
- PATCH : to modify partially a resource in the server.
Response codes in HTTP
The most common are:
- 4XX - Error in client side
- 5XX - Error in server
4.2. Understand fundamentals of HTML forms
A html form has these attributes:
- action : resource
- method : GET or POST
- GET : add form data to the URL using ? as separator (QueryString)
- POST : the data is sent into the body.
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| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <title>FORM EXAMPLE</title> | |
| <style> | |
| p { | |
| border:1px solid grey; | |
| padding:10px; | |
| margin:30px; | |
| } | |
| </style> | |
| </head> | |
| <body> | |
| <form action="order.jsp" method="GET" enctype="text/plain" name="sendInfo"> | |
| <p> | |
| ORDER <br> | |
| <input type="text" maxlength="20" size="20" name="order"> | |
| </p> | |
| <p> | |
| TAKE AWAY <br> | |
| <input type="Radio" name="takeAway" value="N" checked> No<br/> | |
| <input type="Radio" name="takeAway" value="Y"> Yes<br/> | |
| </p> | |
| <p> | |
| SIDES/DRINKS <br> | |
| <input type="checkbox" name="topic" value="chips" checked>chips<br/> | |
| <input type="checkbox" name="topic" value="salad" checked>salad<br/> | |
| <input type="checkbox" name="topic" value="coke">coke<br/> | |
| <textarea name="other" cols="20" rows="10">Other</textarea> | |
| </p> | |
| <p> | |
| MENU NUMBER <br> | |
| <select> | |
| <option value="menu1">menu1</option> | |
| <option value="menu2">menu2</option> | |
| <option value="menu3">menu3</option> | |
| </select> | |
| </p> | |
| <input type="Button" name="bt" value="Send"> | |
| </form> | |
| </body> | |
| </html> |
- Textfield
- Radiobutton
- Checkbox
- Buttons
- SelectionList
- TextArea
When the submit button is clicked the form-data is sent to a page on the server called "order.jsp"
See next post The Servlet's Environment (part2)
OCEJWCD (SCWCD) - 1Z0-899 - Web Component Developer Certification
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