PEAK XOOPS - D3 Pipes Introduction (3)

Look the flow of (A) with detail.

(A) Outer XML fetch/parse pattern
XML fetching -> convert to UTF8 -> XML parsing -> convert to internal encoding -> extraction -> clipping

1) fetching XML string (fetch)
This must be used with parser.
This joint passes a XML sting to next joint. (without input)

2) converting XML string to UTF-8 (utf8to)
This joint converts from a XML string to a XML string.
This joints is disabled default because almost all RSS are encoded by UTF-8

3) XML parsing into array (parse)
This joint converts from a XML string to some entries can be treated as pipe data.

4) converting entries from UTF-8 to internal encoding (utf8to)
This joint converts from pipe data to pipe data recursively

5) extracting entries (filter)
This joint filters entries.
Input should be pipe data, also output is pipe data.
This joint can be placed after clip, union etc.

6) clipping into local (clip)
This joint stores entries into DB etc.
It is important that clipping_id is assigned for each entries.
Using clipping_id, you can post a comment/mark to an entry.

To distinguish the entry is stored formerly or not, "fingerprint" field is used.
With RSS2, <guid> of <item> should be the fingerprint, though <id> of <entry> should be fingerprint with ATOM.