REQUEST DOCUMENT

REQUEST DOCUMENT FROM url

../graphics/sbo1.gif

 WITH [with-clause]

../graphics/sbc1.gif

../graphics/sbo1.gif

 RETURN [return-clause]

../graphics/sbc1.gif
RESPONSE http-response-code  
[GIVING natural-error-number]

This document covers the following topics:

For an explanation of the symbols used in the syntax diagram, see Syntax Symbols.

Related Statement: PARSE XML

Belongs to Function Group: Internet and XML

Function

The REQUEST DOCUMENT statement is used to retrieve and upload documents on the internet as described in REQUEST DOCUMENT in Statements for Internet and XML Access in the Programming Guide.

For information on Unicode support, see REQUEST DOCUMENT in the Unicode and Code Page Support documentation.

See also the description of the Natural profile and session parameter RQTOUT, which specifies the timeouts used for HTTP requests issued internally by the REQUEST DOCUMENT statement.

Restrictions for Cookies

Under the HTTP Protocol, a server uses cookies to maintain state information on the client workstation.

REQUEST DOCUMENT is implemented using internet option settings. This means that, depending on the security settings, cookies will be used.

If the internet option setting Disabled is set, no cookies will be sent, even if a cookie header (header-name-out/header-value-out) is sent.

For server environments, do not use the internet option setting Prompt. This setting leads to a "hanging" server, because no client will be able to answer the prompt.

Cookies are handled automatically by the Windows API. This means that, if cookies are enabled in the browser, all incoming cookies will be saved and sent automatically with the next request.

Syntax Description

Operand Definition Table:

Operand Possible Structure Possible Formats Referencing Permitted Dynamic Definition
url C S       A                       yes no
http-response-code   S               I4               yes yes
natural-error-number   S               I4               yes no

Syntax Element Description:

Syntax Element Description
url
Location of Document:

url is the URL to access a document.

with-clause
WITH Clause:

See with-clause.

return-clause
RETURN Clause:

See return-clause.

http-response-code
RESPONSE:

http-response-code is the HTTP response status code returned for the request, for example: 200 (request completed).

See also HTTP Responses Redirected and Denied.

For a list of possible HTTP status codes, refer to the RFC 2616 memorandum published by the World Wide Web Consortium (W3C).

natural-error-number
GIVING Option:
natural-error-number contains the 4-digit Natural error number if the request could not be performed.

with-clause

[USER user-id]
[PASSWORD user-password]
[HEADER {[NAME] header-name-out [VALUE] header-value-out} ...]
[DATA {ALL outbound-document [ENCODED [[IN] CODEPAGE code-page-out]]
      |{[NAME] variable-name-out [VALUE] variable-value-out} ...}]

The with-clause is used to specify optional user/password, header and data details for the request.

An empty with-clause (that is, no value specified after WITH) is ignored.

Operand Definition Table:

Operand Possible Structure Possible Formats Referencing Permitted Dynamic Definition
user-id C S       A                       yes no
user-password C S       A                       yes no
header-name-out C S       A                       yes no
header-value-out C S       A   N P I F   D T L     yes no
outbound-document C S       A U N P I F B D T L     yes no
code-page-out C S       A                       yes no
variable-name-out C S       A                       yes no
variable-value-out C S       A   N P I F   D T L     yes no

Syntax Element Description:

Syntax Element Description
user-id
USER:

user-id is the ID of the user that will be used for the request.

user-password
PASSWORD:

user-password is the password of the user that will be used for the request.

header-name-out

header-value-out

HEADER NAME/VALUE Option:

header-name-out and header-value-out can only be used in conjunction with each other:

  • header-name-out is the name of a header variable sent with this request.

  • header-value-out is the value of a header variable sent with this request.

header-name-out:

Header names must not contain a carriage return (CR), a line feed (LF) or a colon (:). This will not be checked by the REQUEST DOCUMENT statement. For valid header names, see the HTTP specifications. For compatibility with the web interface, header names can be written with underscore (_) instead of a dash (-). (Internally, the underscore is replaced by a dash).

header-value-out:

Header values are not allowed to contain CR/LF. This will not be checked by the REQUEST DOCUMENT statement. For valid header values and formats, see the HTTP specifications.

See also Automatically Generated Headers.

outbound-document
DATA ALL Option:

outbound-document is a complete document that is to be sent. This value is needed for the HTTP REQUEST-METHOD PUT (see Automatically Generated Headers).

code-page-out
DATA ALL ENCODED Option:

Data transfer with the REQUEST DOCUMENT statement normally does not involve any code page conversion. If you want to encode outgoing data in a specific code page, use the CODEPAGE option:

outbound-document will be encoded from the default code page (value of the system variable *CODEPAGE) to the code page given in code-page-out.

Encoding and Charset Attributes:

If the outbound document contains an encoding (XML) or a charset (HTML) attribute, we recommend that the value of the ENCODED option maps the attribute value of the document.

Example: If an outbound XML document contains the attribute encoding ="UTF-8", code the REQUEST DOCUMENT statement with the option DATA ALL #DOCUMENT ENCODED CODEPAGE 'UTF-8'.

variable-name-out

variable-value-out
DATA NAME/VALUE Option:

variable-name-out and variable-value-out request only specific DATA variable information instead of the complete document. They can only be used in conjunction with each other:

  • variable-name-out is the name of a DATA variable to be sent with this request.

  • variable-value-out is the value of a DATA variable to be sent with this request. This value is needed for the HTTP REQUEST-METHOD POST (URL encoding necessary, especially ampersand (&), equal sign (=), percent sign (%) characters).

Restriction:

If variable-name-out and variable-value-out are given and the communication is http:// or https://, by default, the REQUEST-METHOD POST (see Automatically Generated Headers) with content type application/x-www-form-urlencoded is used. During the request, variable-name-out and variable-value-out will be separated by equal sign (=) and ampersand (&) characters. Therefore, the operands are not allowed to contain equal sign (=), ampersand (&) and, because of URL encoding, percent sign (%) characters. These characters are considered reserved and need to be encoded as indicated in Reserved Characters.

return-clause

[HEADER [ALL header-all-in] [[NAME] header-name-in [VALUE] header-value-in ...]]
[PAGE inbound-document [ENCODED [[FOR TYPES mime-type ...] [IN] CODEPAGE code-page-in]]]

Operand Definition Table:

Operand Possible Structure Possible Formats Referencing Permitted Dynamic Definition
header-all-in   S       A                       yes yes
header-name-in C S       A                       yes no
header-value-in   S  A *     A   N P I F B D T L     yes yes
inbound-document   S       A U         B           yes yes
mime-type C S       A                       yes no
code-page-in C S       A                       yes no

This clause can be used to specify return information for the headers and/or the document.

Syntax Element Description:

Syntax Element Description
header-all-in
HEADER ALL Option:

header-all-in contains all header data delivered with the HTTP response.

The first line contains the status information and all following lines contain the headers as pairs of name and value. The names always end in a colon (:) and the values end in a line feed (LF). Internally, all carriage returns/line feeds (CR/LF) are transformed into line feeds (LF).

header-name-in

header-value-in

HEADER NAME/VALUE Option:

header-name-in and header-value-in return only specific header information. They can only be used in conjunction with each other:

  • header-name-in is the name for the header information returned by the HTTP request.

    For compatibility with the web interface, header names can be written with underscore (_) instead of dash (-) characters.

    Internally, the underscore is replaced by a dash. If header-name-in is a blank string, the status information is returned, for example: 

    HTTP/1.0 200 OK

  • header-value-in is the scalar or array value required to receive the header data returned by the HTTP request.

    An array definition is required if more than one occurrence of the same header is expected, for example, multiple Set-Cookie headers.

    Only one dimension of a multi-dimensional array may contain an index range (see Example 9).

    An X-array must be materialized before you can use it.

    If the number of array occurrences exceeds the number of headers, the unused occurrences are reset. If the number of headers exceeds the number of array occurrences, the remaining header values are ignored.

    For an example of an array definition, see Example 9 - RETURN HEADER NAME VALUE with Array Definition.

inbound-document
PAGE Option:

inbound-document is the document returned for this request. No encoding at all of the returned page will be done; that is, the page will remain encoded as delivered from the HTTP server.

code-page-in
PAGE ENCODED Option:

Data transfer with the REQUEST DOCUMENT statement normally does not involve any code page conversion. If you want to encode incoming data in a specific code page, use the ENCODED option:

If necessary, inbound-document will be encoded in the default code page (value of system variable *CODEPAGE) of the Natural session.

If the value of code-page-in is blank, no conversion occurs. inbound-document is then encoded in the default code page (profile parameter CP in the Configuration Utility).

Note:
"Returned MIME type contains an encoding" means that the HTTP server returns a content-type header with a charset= clause, for example: charset=ISO-8859-1.

mime-type
PAGE ENCODED FOR TYPES Option:

As a response of an HTTP/HTTPS request, incoming data may contain binary data (for example, image/gif) or character data (for example, text/html). Together with the response, the REQUEST DOCUMENT statement receives a parameter which specifies the type of content of the requested document (MIME type, also known as internet media type). This parameter may contain information about the code page in which the document is encoded. mime-type is the list of MIME types for which an encoding of the returned document in inbound-document will be performed.

If the returned MIME type contains an encoding, inbound-document will be encoded from this code page to the default code page (A/B) or (U).

If the returned MIME type does not contain an encoding, then inbound-document will be encoded from the code page defined with code-page-in to the default code page (value of the system variable *CODEPAGE) (A/B) or (U).

If the returned MIME type does not contain an encoding, then an additional check is performed if the returned MIME type matches one of the types given with mime-type. If a match is found, inbound-document will be encoded from the code page defined with code-page-in to the default code page (A/B) or (U).

Automatically Generated Headers

For an HTTP request, some headers are required, for example: REQUEST-METHOD or content type. These headers will be automatically generated depending on the parameters given with the REQUEST DOCUMENT statement.

Note:
It is possible to overwrite the automatically generated headers. Natural will not check them for errors. Unexpected errors may occur.

HTTP REQUEST-METHOD

The REQUEST DOCUMENT statement supports the following HTTP REQUEST-METHODs: HEAD, POST, GET and PUT.

The following table shows the HTTP REQUEST-METHOD generated depending on the given operands:

  WITH HEADER WITH DATA RETURN HEADER RETURN PAGE
HEAD o - x -
POST o x o x
GET o - o x
PUT o DATA ALL * o o

In addition to the standard REQUEST-METHODs mentioned above, the method DELETE can be specified in a REQUEST-METHOD header.

Explanation:

o Optional. Operand can be optionally specified.
- Operand cannot be specified.
x Operand is always specified.
* Only applies to DATA ALL and not DATA NAME VALUE.

Content Type

The REQUEST-METHOD POST requires a content-type header for the HTTP request. If no content type is explicitly specified, Natural inserts the following default content-type header into the request: 

application/x-www-form-urlencoded

URL Encoding for Special Characters

When sending POST data with the content type application/x-www-form-urlencoded, certain characters must be represented by means of URL encoding, which means substituting the character with %hexadecimal-character-code. Some basic details are given here:

For full details of when and why URL encoding is necessary, refer to the memorandums RFC 1630, RFC 1738 and RFC 1808 published by the World Wide Web Consortium (W3C).

Non-ASCII Characters

All non-ASCII characters (that is, valid ISO 8859/1 characters that are not also ASCII characters) must be URL encoded, for example, the file köln.html would appear in an URL as k%F6ln.html.

Unsafe Characters

URL encode the following unsafe characters when you request web pages to avoid server failures:

Unsafe Character URL Encoding
the tab character %09
the space character %20
[ %5B
\ %5C
] %5D
^ %5E
` %60
{ %7B
| %7C
} %7D
~ %7E

Reserved Characters

Some characters have special meanings in URLs, such as the colon (:) that separates the URL scheme from the rest of the URL, the double slash (//) that indicates that the URL conforms to the Common Internet Scheme syntax and the percent sign (%). Generally, when these characters appear as parts of file names, they must be URL encoded to distinguish them from their special meaning in URLs (this is a simplification, refer to the RFCs mentioned earlier for full details).

Reserved characters are:

Reserved Character URL Encoding
" %22
# %23
% %25
& %26
+ %2B
, %2C
/ %2F
: %3A
< %3C
= %3D
> %3E
? %3F
@ %40

HTTP Responses Redirected and Denied

For a list of HTTP status codes, refer to the RFC 2616 memorandum published by the World Wide Web Consortium (W3C).

The following special considerations apply to the HTTP responses for redirected and denied requests:

Response 301 - 303 (Redirected)

The HTTP response codes 301, 302 and 303 mean that the URL where the requested document resides has changed and that the request was therefore redirected to another URL. As a response, the return header with the name LOCATION will be displayed. This header contains the URL where the requested page has moved to. A new REQUEST DOCUMENT request can be used to retrieve the page moved.

HTTP browsers redirect automatically to the new URL, but the REQUEST DOCUMENT statement does not handle redirection automatically.

Response 401 (Denied/Unauthorized)

The HTTP response code 401 means that the requested page can only be accessed if a valid user ID and password are provided with the request. As a response, the return header with the name WWW-AUTHENTICATE will be delivered with the REALM needed for this request.

HTTP browsers normally display a dialog with user ID and password, but with the REQUEST DOCUMENT statement, no dialog is displayed.

Examples

Note:
There is an example dialog V5-RDOC for this statement in the example library SYSEXV.

Example 1 - General Request

REQUEST DOCUMENT FROM "http://bolsap1:5555/invoke/sap.demo/handle_RFC_XML_POST" 
  WITH
    USER #User PASSWORD #Password
    DATA
    NAME 'XMLData'       VALUE #Queryxml
    NAME 'repServerName' VALUE 'NT2'
  RETURN
    PAGE #Resultxml
RESPONSE #rc

Example 2 - Simple GET Request (no data)

REQUEST DOCUMENT FROM "http://pcnatweb:8080"
  RETURN
    PAGE #Resultxml
RESPONSE #rc

Example 3 - Simple HEAD Request (no return page)

REQUEST DOCUMENT FROM "http://pcnatweb"
RESPONSE #rc

Example 4 - Simple POST Request (default REQUEST-METHOD)

REQUEST DOCUMENT FROM "http://pcnatweb/cgi-bin/nwwcgi.exe/sysweb/nat-env"
  WITH 
    DATA 
    NAME 'XMLData'       VALUE #Queryxml
    NAME 'repServerName' VALUE 'NT2'
  RETURN
    PAGE #Resultxml
RESPONSE #rc

Example 5 - Simple PUT Request (with DATA ALL)

REQUEST DOCUMENT FROM "http://pcnatweb/test.txt"
  WITH 
    DATA ALL     #document
  RETURN
    PAGE #Resultxml
RESPONSE #rc

Example 9 - RETURN HEADER NAME VALUE with Array Definition

DEFINE DATA        
LOCAL
1 #FROM      (A) DYNAMIC
1 #HEADER    (A) DYNAMIC
1 #PAGE      (A) DYNAMIC
1 #COOKIES (A20/1:3,1:4,2:5)
1 #RC      (I4)
END-DEFINE
ASSIGN #FROM = 'http://www.myserver.com'
REQUEST DOCUMENT FROM #FROM
   RETURN
        HEADER NAME 'Set-Cookie' VALUE #COOKIES(1,2:3,3)
        PAGE   #PAGE  
        RESPONSE #RC 
PRINT #COOKIES(*,*,*)
END

In the example program above, invalid array definitions (with multiple dimensions) would be: 

RETURN HEADER NAME 'Set-Cookie' VALUE #COOKIES(1:3,2:3,3)
RETURN HEADER NAME 'Set-Cookie' VALUE #COOKIES(*,2,*)