[FLINK-8047] [http connector] Add HTTP Sink to allow sending output to HTTP server

[genged]

What is the purpose of the change

Add HttpSink to enable sending events to an Http server

Brief change log

• Added a new connector flink-http-connector
• Created HttpSink that allows configuration of the HttpClient and the ResponseHandler
• The sink sends each element of the stream as a separate HTTP POST request to the configured server

Verifying this change

This change added tests and can be verified as follows:

• Added HttpSinkTest that starts a local cluster and an http server

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): yes
• The public API, i.e., is any changed class annotated with @Public(Evolving): no
• The serializers: no
• The runtime per-record code paths (performance sensitive): don't know
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Yarn/Mesos, ZooKeeper: no
• The S3 file system connector: no

Documentation

• Does this pull request introduce a new feature? yes
• If yes, how is the feature documented? JavaDocs

[kl0u]

Hi @genged and sorry for the pretty late review.

This sink seems to be pretty specific and I am not so sure how interesting it is to other users. Given this, and previous experience with connectors that ended up being more of a maintenance burden for the community rather than enablers for new usecases, I would recommend to wait until the Ecosystem Website is up (which is going to happen soon), and contribute the sink there as a start. You can find the discussion for the new site here.

This step will help at gauging the interest of the community on the sink and based on that, it may become part of the master. Until then, and if you are ok with it, I would recommend to close this PR.

What do you think?

[flinkbot]

CI report:

• 6e7c2a3 : FAILURE Build

Bot commands

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• @flinkbot run travis re-run the last Travis build

[kl0u]

Hi @genged , I will close this PR as there does not seem to have much activity.