TIdNNTP.XHDR Method (string, string, TIdStrings)

NNTP extension to retrieve article headers using selection criteria.

Approved Lines Xref

The range of articles to be searched is specifies by the AParm argument. AParm must be in the following forms:

an article number

an article number followed by a dash to indicate all following articles

an article number followed by a dash and another article number

For example, if the following values of AParm would result in the corresponding action:

23	retrieve article number 23.
1-23	retrieve all available articles number in the range 1 through 23.
23-	retrieve all articles numbered 23 and higher.

Article numbers are transitory. This means that you may specify a range of article numbers, such as 1-5, and you may receive only articles 1,3 and 4. This does not mean you have done anything wrong. The missing articles may have been expired (removed from the server), or for some other reason not under your control have become unavailable.

Pascal

procedure XHDR(
    AHeader: string; 
    AParam: string; 
    AResponse: TIdStrings
); overload;

Parameters

Parameters	Description
AHeader	Header to be searched.
AResponse	Server response.
AParm	Range of articles to search.

Description

XHDR is a method that retrieves specific article headers specified in AHeader from an article index or a range of articles as specified in AParam. XHDR is an extension to the NNTP protocol.

XHDR calls SendCmd using the arguments in AHeader and AParam.

XHDR calls Capture to store the server response lines in AResponse. You must have previously executed the SelectGroup command in order for this command to return a meaningful response.

AHeader can contain any of the following values for an RFC 1036-compliant server:

From

Date

Newsgroups

Subject

Message-ID

Path

The following headers may or may not work depending on the server configuration. Also, it should be noted that servers can and many do have local header definitions. If you know what these header designations are you can of course pass them in the AHeader argument.

Reply-To

Sender

Followup-To

Expires

References

Control

Distribution

Organization

Keywords