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Http request&response


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Http request&response

  1. 1. Http Request & Response
  2. 2. HyperText Transfer Protocol (HTTP)     most popular application protocol used in the Internet (or The WEB) An HTTP client sends a request message to an HTTP server The server, in turn, returns a response message. In other words, HTTP is a pull protocol, the client pulls information from the server (instead of server pushes information down to the client). HTTP is a stateless protocol. In other words, the current request does not know what has been done in the previous requests.
  3. 3. Browser
  4. 4. Uniform Resource Locator (URL) A URL (Uniform Resource Locator) is used to uniquely identify a resource over the web. URL has the following syntax: protocol://hostname:port/path-and-file-name There are 4 parts in a URL: Protocol: The application-level protocol used by the client and server, e.g., HTTP, FTP, and telnet. Hostname: The DNS domain name (e.g., or IP address (e.g., of the server. Port: The TCP port number that the server is listening for incoming requests from the clients. Path-and-file-name: The name and location of the requested resource, under the server document base directory. For example, in the URL, the communication protocol is HTTP; the hostname is The port number was not specified in the URL, and takes on the default number, which is TCP port 80 for HTTP. The path and file name for the resource to be located is "/docs/index.html". Other examples of URL are:
  5. 5. Important Default Port numbers 443 TCP Hypertext Transfer Protocol over TLS/SSL (HTTPS). 115 TCP Simple/secure File Transfer Protocol (SFTP). 80 TCP Hypertext Transfer Protocol (HTTP). 21 TCP FTP control (command). 22 TCP Secure Shell (SSH) — used for secure logins. 23 TCP Telnet protocol. 25 TCP Simple Mail Transfer Protocol (SMTP). 115 TCP Simple File Transfer Protocol (SFTP). 110 TCP Post Office Protocol v3 (POP3). 1414TCP IBM WebSphere MQ (formerly known as MQSeries). 9060TCP WebSphere Application Server Administration Console. 9080TCP WebSphere Application Server HTTP Transport (port 1) default. 8080TCP Apache Tomcat. 5432TCP PostgreSQL database system. 3306TCP MySQL database system. 1521TCP Oracle database default listener.
  6. 6. Http Request Message
  7. 7. Http Request Message Format The format of an HTTP request message is as follow:
  8. 8. Http Request Message Request Line The first line of the header is called the request line, followed by optional request headers. The request line has the following syntax: request-method-name request-URI HTTP-version request-method-name: HTTP protocol defines a set of request methods, e.g., GET, POST, HEAD, and OPTIONS. The client can use one of these methods to send a request to the server. * case sensitive and must be in uppercase. request-URI: specifies the resource requested. HTTP-version: Two versions are currently in use: HTTP/1.0 and HTTP/1.1. Examples of request line are: GET /test.html HTTP/1.1 HEAD /query.html HTTP/1.0 POST /index.html HTTP/1.1
  9. 9. Http Request Message Request Headers The request headers are in the form of name:value pairs. Multiple values, separated by commas, can be specified. request-header-name: request-header-value1, requestheader-value2, ... Examples of request headers are: Host: Connection: Keep-Alive Accept: image/gif, image/jpeg, */* Accept-Language: us-en, fr, cn username=vignesh&password=qwer1234&......
  10. 10. Http Request Message Format GET /docs/index.html HTTP/1.1 Host: Accept: image/gif, image/jpeg, */* Accept: */* Accept-Language: en-us Accept-Encoding: gzip, deflate Referer:http://localhost:8080/home Cookie:JSESSIONID=DFC52DC1584F89D94009014A77C111EC;city=Coimbatore; User-Agent:Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Ubuntu Chromium/32.0.1700.102 Chrome/32.0.1700.102 Safari/537.36 Cache-Control: max-age=0 (blank line)
  11. 11. Http Response HTTP/1.1 200 OK Server: Apache-Coyote/1.1 Expires: Sun, 01 Mar 2015 13:46:19 GMT Cache-Control: max-age=31556926, must-revalidate Date: Sat, 01 Mar 2014 07:57:33 GMT Set-Cookie:JSESSIONID=1D9B00464C03A0923E0AE77ADE16416A; Path=/; HttpOnly Content-Type:text/html;charset=UTF-8 <html><body><h1>It works!</h1></body></html>
  12. 12. HTTP Response Message
  13. 13. Http Response Message Status Line The first line is called the status line, followed by optional response header(s). The status line has the following syntax: HTTP-version status-code reasonphrase HTTP-version: The HTTP version used in this session. Either HTTP/1.0 and HTTP/1.1. status-code: a 3-digit number generated by the server to reflect the outcome of the request.
  14. 14. Http Response Message Response Headers The response headers are in the form name:value pairs: response-header-name: response-header-value1, response-header-value2, ... Examples of response headers are: Content-Type: text/html Content-Length: 35 Connection: Keep-Alive Keep-Alive: timeout=15, max=100
  15. 15. Http Response Message
  16. 16. Http Response Status Code Some commonly encountered status codes are: 100 Continue: The server received the request and in the process of giving the response. 200 OK: The request is fulfilled. 301 Move Permanently: The resource requested for has been permanently moved to a new location. The URL of the new location is given in the response header called Location. The client should issue a new request to the new location. Application should update all references to this new location.
  17. 17. Http Request Using HTML Form <html> <head><title>Login</title></head> <body> <h2>LOGIN</h2> <form method="get/post/delete" action="/user/login"> Username: <input type="text" name="user" size="25" /><br /> Password: <input type="password" name="pw" size="10" /><br /><br />
  18. 18. HTML Form Fields A form contains fields. The types of field include: Text Box: produced by <input type="text">. Password Box: produced by <input type="password">. Radio Button: produced by <input type="radio">. Checkbox: produced by <input type="checkbox">. Selection: produced by <select> and <option>. Text Area: produced by <textarea>. Submit Button: produced by <input type="submit">.
  19. 19. HTML Form Fields The query string can be sent to the server using either HTTP GET or POST request method, which is specified in the <form>'s attribute "method". <form method="get" action="url"> If GET request method is used, the URL-encoded query string will be appended behind the requestURI after a "?" character, i.e., GET request-URI?query-string HTTP-version (other optional request headers)
  20. 20. HTML Form Fields <html> <head><title>Login</title></head> <body> <h2>LOGIN</h2> <form method="get" action="/bin/login"> Username: <input type="text" name="user" size="25" /><br /> Password: <input type="password" name="pw" size="10" /><br /><br /> <input type="hidden" name="action" value="login" /> <input type="submit" value="SEND" /> </form> </body> </html>
  21. 21. HTML Form Fields <html> <head><title>Login</title></head> <body> <h2>LOGIN</h2> <form method="post" action="/bin/login"> Username: <input type="text" name="user" size="25" /><br /> Password: <input type="password" name="pw" size="10" /><br /><br /> <input type="hidden" name="action" value="login" /> <input type="submit" value="SEND" /> </form> </body> </html>
  22. 22. HTML Form Fields File Upload using multipart/form-data POST Request <html> <head><title>File Upload</title></head> <body> <h2>Upload File</h2> <form method="post" enctype="multipart/form-data" action="servlet/UploadServlet"> Who are you: <input type="text" name="username" /><br /> Choose the file to upload: <input type="file" name="fileID" /><br /> <input type="submit" value="SEND" /> </form> </body> </html>
  23. 23. Thank you