Today content type detection on an input stream works by peeking up to
twenty bytes into the stream. If the stream is headed by more whitespace
than twenty bytes, we might fail to detect the content type. We should
be ignoring this whitespace before attempting to detect the content
type. This commit does that by ignoring all leading whitespace in an
input stream before attempting to guess the content type.
This change adds Expected Reciprocal Rank (ERR) as a ranking evaluation metric
as descriped in:
Chapelle, O., Metlzer, D., Zhang, Y., & Grinspan, P. (2009).
Expected reciprocal rank for graded relevance.
Proceeding of the 18th ACM Conference on Information and Knowledge Management.
https://doi.org/10.1145/1645953.1646033
ERR is an extension of the classical reciprocal rank to the graded relevance
case and assumes a cascade browsing model. It quantifies the usefulness of a
document at rank `i` conditioned on the degree of relevance of the items at ranks
less than `i`. ERR seems to be gain traction as an alternative to (n)DCG, so it
seems like a good metric to support. Also ERR seems to be the default optimization
metric used for training in RankLib, a widely used learning to rank library.
Relates to #29653
This is the first x-pack API we're adding to the high level REST client
so there is a lot to talk about here!
= Open source
The *client* for these APIs is open source. We're taking the previously
Elastic licensed files used for the `Request` and `Response` objects and
relicensing them under the Apache 2 license.
The implementation of these features is staying under the Elastic
license. This lines up with how the rest of the Elasticsearch language
clients work.
= Location of the new files
We're moving all of the `Request` and `Response` objects that we're
relicensing to the `x-pack/protocol` directory. We're adding a copy of
the Apache 2 license to the root fo the `x-pack/protocol` directory to
line up with the language in the root `LICENSE.txt` file. All files in
this directory will have the Apache 2 license header as well. We don't
want there to be any confusion. Even though the files are under the
`x-pack` directory, they are Apache 2 licensed.
We chose this particular directory layout because it keeps the X-Pack
stuff together and easier to think about.
= Location of the API in the REST client
We've been following the layout of the rest-api-spec files for other
APIs and we plan to do this for the X-Pack APIs with one exception:
we're dropping the `xpack` from the name of most of the APIs. So
`xpack.graph.explore` will become `graph().explore()` and
`xpack.license.get` will become `license().get()`.
`xpack.info` and `xpack.usage` are special here though because they
don't belong to any proper category. For now I'm just calling
`xpack.info` `xPackInfo()` and intend to call usage `xPackUsage` though
I'm not convinced that this is the final name for them. But it does get
us started.
= Jars, jars everywhere!
This change makes the `xpack:protocol` project a `compile` scoped
dependency of the `x-pack:plugin:core` and `client:rest-high-level`
projects. I intend to keep it a compile scoped dependency of
`x-pack:plugin:core` but I intend to bundle the contents of the protocol
jar into the `client:rest-high-level` jar in a follow up. This change
has grown large enough at this point.
In that followup I'll address javadoc issues as well.
= Breaking-Java
This breaks that transport client by a few classes around. We've
traditionally been ok with doing this to the transport client.
ObjectParser should throw XContentParseExceptions, not IAE. A dedicated parsing
exception can includes the place where the error occurred.
Closes#30605
* Move ObjectParser into the x-content lib
This moves `ObjectParser`, `AbstractObjectParser`, and
`ConstructingObjectParser` into the libs/x-content dependency. This decoupling
allows them to be used for parsing for projects that don't want to depend on the
entire Elasticsearch jar.
Relates to #28504
* Begin moving XContent to a separate lib/artifact
This commit moves a large portion of the XContent code from the `server` project
to the `libs/xcontent` project. For the pieces that have been moved, some
helpers have been duplicated to allow them to be decoupled from ES helper
classes. In addition, `Booleans` and `CheckedFunction` have been moved to the
`elasticsearch-core` project.
This decoupling is a move so that we can eventually make things like the
high-level REST client not rely on the entire ES jar, only the parts it needs.
There are some pieces that are still not decoupled, in particular some of the
XContent tests still remain in the server project, this is because they test a
large portion of the pluggable xcontent pieces through
`XContentElasticsearchException`. They may be decoupled in future work.
Additionally, there may be more piecese that we want to move to the xcontent lib
in the future that are not part of this PR, this is a starting point.
Relates to #28504
Alpar Torok
Armin Braun
Jason Tedor
Christoph Büscher
Nik Everett
Tanguy Leroux
Lee Hinman
Adrien Grand