Summary of UTL_URL Subprograms

Table 102-2 UTL_URL Package Subprograms

Subprogram	Description
ESCAPE Function	Returns a URL with illegal characters (and optionally reserved characters) escaped using the %2-digit-hex-code format
UNESCAPE Function	Unescapes the escape character sequences to their original forms in a URL. Convert the %XX escape character sequences to the original characters

ESCAPE Function

This function returns a URL with illegal characters (and optionally reserved characters) escaped using the %2-digit-hex-code format.

Syntax

UTL_URL.ESCAPE (
   url                   IN VARCHAR2,
   escape_reserved_chars IN BOOLEAN  DEFAULT FALSE,
   url_charset           IN VARCHAR2 DEFAULT
                                     utl_http.body_charset)
   RETURN VARCHAR2;

Parameters

Table 102-3 ESCAPE Function Parameters

Parameter	Description
url (IN)	The original URL
escape_reserved_chars (IN)	Indicates whether the URL reserved characters should be escaped. If set to TRUE, both the reserved and illegal URL characters are escaped. Otherwise, only the illegal URL characters are escaped. The default value is FALSE.
url_charset (IN)	When escaping a character (single-byte or multibyte), what is the target character set that character should be converted to before the character is escaped in %hex-code format? If url_charset is NULL, the database charset is assumed and no character set conversion will occur. The default value is the current default body character set of the UTL_HTTP package, whose default value is ISO-8859-1. The character set can be named in Internet Assigned Numbers Authority (IANA) or Oracle naming convention.

Usage Notes

Use this function to escape URLs that contain illegal characters as defined in the URL specification RFC 2396. The legal characters in URLs are:

• A through Z, a through z, and 0 through 9
• Hyphen (-), underscore (_), period (.), exclamation point (!), tilde (~), asterisk (*), accent ('), left parenthesis ( ( ), right parenthesis ( ) )

The reserved characters consist of:

• Semi-colon (;) slash (/), question mark (?), colon (:), at sign (@), ampersand (&), equals sign (=), plus sign (+), dollar sign ($), and comma (,)

Many of the reserved characters are used as delimiters in the URL. You should escape characters beyond those listed here by using escape_url. Also, to use the reserved characters in the name-value pairs of the query string of a URL, those characters must be escaped separately. An escape_url cannot recognize the need to escape those characters because once inside a URL, those characters become indistinguishable from the actual delimiters. For example, to pass a name-value pair $logon=scott/tiger into the query string of a URL, escape the $ and / separately as %24logon=scott%2Ftiger and use it in the URL.

Normally, you will escape the entire URL, which contains the reserved characters (delimiters) that should not be escaped. For example:

utl_url.escape('http://www.acme.com/a url with space.html')

Returns:

http://foo.com/a%20url%20with%20space.html

In other situations, you may want to send a query string with a value that contains reserved characters. In that case, escape only the value fully (with escape_reserved_chars set to TRUE) and then concatenate it with the rest of the URL. For example:

url := 'http://www.acme.com/search?check=' || utl_url.escape
('Is the use of the "$" sign okay?', TRUE);

This expression escapes the question mark (?), dollar sign ($), and space characters in 'Is the use of the "$" sign okay?' but not the ? after search in the URL that denotes the use of a query string.

The Web server that you intend to fetch Web pages from may use a character set that is different from that of your database. In that case, specify the url_charset as the Web server character set so that the characters that need to be escaped are escaped in the target character set. For example, a user of an EBCDIC database who wants to access an ASCII Web server should escape the URL using US7ASCII so that a space is escaped as %20 (hex code of a space in ASCII) instead of %40 (hex code of a space in EBCDIC).

This function does not validate a URL for the proper URL format.

UNESCAPE Function

This function unescapes the escape character sequences to its original form in a URL, to convert the %XX escape character sequences to the original characters.

Syntax

UTL_URL.UNESCAPE (
   url            IN VARCHAR2,
   url_charset    IN VARCHAR2 DEFAULT utl_http.body_charset)
                  RETURN VARCHAR2;

Parameters

Table 102-4 UNESCAPE Function Parameters

Parameter	Description
url (IN)	The URL to unescape
url_charset (IN)	After a character is unescaped, the character is assumed to be in the source_charset character set and it will be converted from the source_charset to the database character set before the URL is returned. If source_charset is NULL, the database charset is assumed and no character set conversion occurred. The default value is the current default body character set of the UTL_HTTP package, whose default value is "ISO-8859-1". The character set can be named in Internet Assigned Numbers Authority (IANA) or Oracle naming convention.

Usage Notes

The Web server that you receive the URL from may use a character set that is different from that of your database. In that case, specify the url_charset as the Web server character set so that the characters that need to be unescaped are unescaped in the source character set. For example, a user of an EBCDIC database who receives a URL from an ASCII Web server should unescape the URL using US7ASCII so that %20 is unescaped as a space (0x20 is the hex code of a space in ASCII) instead of a ? (because 0x20 is not a valid character in EBCDIC).

This function does not validate a URL for the proper URL format.