docs: metha command line invocation

[miku]

Thanks for including metha into your research and the benchmark.

I noticed that in your README, the metha invocation reads as:

$ metha-sync https://oai.deutsche-digitale-bibliothek.de/ -set 10443700598299947xcYN -format ddb

This works, but due to a limitation of the flag parser of metha, flags after arguments are ignored (so the above would harvest all of DDB, actually). If you wanted to harvest a set in a specific format, you would have to write:

$ metha-sync -set 10443700598299947xcYN -format ddb https://oai.deutsche-digitale-bibliothek.de/

If I run the above command, the process seems to finish in about 20-30s.

PS. Somehow, I also ran into a HTTP 500: https://oai.deutsche-digitale-bibliothek.de/?from=2023-06-01T00:00:00Z&metadataPrefix=ddb&set=10443700598299947xcYN&until=2023-06-30T23:59:59Z&verb=ListRecords - not sure why.

[karkraeg]

Hi @miku - I will look into this in May as I'll be away for a while. Thanks for your input, I will update the Readme when I can reproduce. The DDB OAI Provider seems dead, as https://oai.deutsche-digitale-bibliothek.de/oai/OAIHandler?verb=Identify and all other links provided here dont seem to work:

Perhaps @mbuechner can say something about that?

[miku]

Thanks, and no rush on this - I just ran into the argument-and-flag-order irritation in another issue.

I confirm some difficulty of getting data from oai.deutsche-digitale-bibliothek.de, e.g. HTTP 502

Proxy Error

The proxy server received an invalid response from an upstream server.
The proxy server could not handle the request GET /oai.

Reason: Error reading from remote server