I'm using the Heritrix 3.1 Java library. Just to be clear, I'm not interested in crawling but only in processing data from compressed WARC (*.warc.gz) files generated by another team. For each WWW document stored in the WARC file, I need some information from the record header, some from the HTTP headers, and the full content of the HTTP payload/body, so I think I need to use the HeaderedArchiveRecord class.
WARCReader warcReader = WARCReaderFactory.get(warcFile);
int inputSequence = -1;
ArchiveRecord record = warcReader.get();
while(record != null){
inputSequence++;
// Skip the 0th record, which is just the archive guff.
if (inputSequence == 0) {
// print some info but do not process this record
}
else if (! record.hasContentHeaders()) {
// print some info but do not process this record
}
else {
HeaderedArchiveRecord hRecord = new HeaderedArchiveRecord(record);
ArchiveRecordHeader archiveHeader = hRecord.getHeader();
gate.Document document = makeDocumentHeritrix(archiveHeader,
inputSequence, hRecord);
//...
}
record.close();
record = warcReader.get(); // line 754
}
warcReader.close();
When I run this, I get an exception with this cause
Caused by: java.io.IOException: Failed to read WARC_MAGIC
at org.archive.io.warc.WARCRecord.parseHeaders(WARCRecord.java:116)
at org.archive.io.warc.WARCRecord.<init>(WARCRecord.java:90)
at org.archive.io.warc.WARCReader.createArchiveRecord(WARCReader.java:94)
at org.archive.io.warc.WARCReader.createArchiveRecord(WARCReader.java:44)
at org.archive.io.ArchiveReader.get(ArchiveReader.java:159)
at
gate.arcomem.batch.Enrichment.makeCorpusWithHeritrix(Enrichment.java:754)
where my line 754 is as marked above. The code in my makeDocumentHeritrix(...)
method used to throw a similar exception but with Failed to find WARC_MAGIC
until I moved the line hrecord.skipHttpHeader();
to before Header[] httpHeader = record.getContentHeaders();
inside it.
I have tried to search the web for examples of code to loop through records in WARC files, but haven't found any, and I recall that when I used heritrix 1.14 several years ago to do something similar, I had to do some weird things to manipulate the offsets in the files, but the related methods in WARCReader are now all private or protected, so I would not expect to have to do that with the newer library.
I had success with the following code:
Iterator<ArchiveRecord> archIt = WARCReaderFactory.get(new File(args[0])).iterator();
while (archIt.hasNext()) {
handleRecord(archIt.next());
}
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