datalinklint runs a series of tests on a VOTable that is supposed to conform to the {links}-response for‐
mat defined in the IVOA DataLink specification, and reports the results. This is not likely to be of use
to normal users, it is intended for people developing or operating DataLink-compliant services to assess
correctness, perhaps with a view to improving compliance.
To run it, you point it at the URL or filename of a VOTable of interest, and it runs various tests on it
and reports them to standard output. Only the input table itself, and if the input location uses HTTP the
HTTP headers, are tested, this validator does not inspect any other resources. As well as validation
checks, some reporting of the table's content (such as a summary of the link defined by each row and a
listing of the defined service descriptors) is provided as INFO-level output for convenience. This can be
suppressed if preferred by use of the report parameter.
This operates in much the same way as the taplint command, and the output has a similar format, though
unlike taplint this command does not divide the testing up into stages. Each report line is of the form:
T-MMMMxN aaaaa... where the parts have the following meanings:
* T: Report type, one of E(rror), W(arning), I(nfo), S(ummary), F(ailure). See the documentation of the
report parameter for further description of what these mean. The report parameter can be used to sup‐
press some of these; only E indicates actual service compliance errors, but including the others may
make it easier to see what's going on.
* MMMM: Message label, which is always the same for messages generated by the same test, is usually
different for messages generated by different tests, and may be somewhat mnemonic.
* x: Continuation indicator, either "-" or "+". In most cases it is "-", indicating the first line of a
message, but multi-line messages (rare) use "-" for the first line and "+" for any continuation
lines.
* N: Sequence number, which is 1 for the first time message T-MMMM is reported, and increases by one
for each subsequent appearance. After a certain maximum (determined by the maxrepeat parameter) addi‐
tional reports with the same code are no longer output individually, but a summary of the number of
reports so discarded is written at the end of the section with the character "x" instead of the se‐
quence number. This behaviour prevents the output being swamped by multiple reports of the same is‐
sue. If the maxrepeat parameter is increased above 9, more than one digit will be used here (so e.g.
for maxrepeat=999, the format would be NNN not N).
* aaaaa...: Message text, a free text description of what is being reported.
If you don't like that format, others may be selected using the format parameter, which currently also
supports JSON. For more flexible interaction with the output you can invoke datalinklint programmatically
and supply your own instance.
As with any validator, this command does not guarantee to pick up everything wrong with the indicated
VOTable, but it tries as hard as it can to check against the rules set out in the DataLink specification
and other related documents as appropriate. A non-exhaustive list of the items checked is:
* VOTable validation à la votlint
* Correct RESOURCE structure of VOTable document
* All required columns are present with mandated metadata
* Optional but documented columns have mandated metadata if present
* Each row contains one of access_url, service_def, error_message
* Service descriptors correctly specified and referenced
* Syntax of error_message column values
* Syntax of content_type column values
* Syntax of semantics column values
* Values of content_qualifier column values if present
* Syntax of link_auth column values if present
* Results for the same ID are contiguous (DataLink 1.1)
* StandardID INFO is present and correct (Datalink 1.1)
* Reported HTTP content-type, if applicable
* Correct serialization (TABLEDATA) is used
* DALI error-response checking, if applicable
At present nochecking is performed on the link targets; tests are confined to the presented document
itself.
HTTP connections made by this validator are flagged in the User-Agent field with the token "(IVOA-test)".
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