Slack Notification Connector

Since CONNECTORS-1119 ManifoldCF has the ability to send notifications on certain job statuses. Notification endpoints are realized by INotificationConnector implementors.

It would be awesome to have a notification connector for Slack channel.

Slack has a HTTP API (https://api.slack.com/web) and there are a lot of java examples showing how to pull this off: https://api.slack.com/community#java
The simplest way for an integration are Slack incoming webhooks

Sample Request

POST https://hooks.slack.com/services/T00000000/B00000000/XXXXXXXXXXXXXXXXXXXXXXXX
Content-type: application/json
{
    "text": "This is a line of text.\nAnd this is another one."
}

We plan to contribute this connector on November 24th 2016 in the context of a Open Source Hackathon at DB Systel GmbH
See https://www.mail-archive.com/dev@manifoldcf.apache.org/msg11050.html

Design

• new connector module connectors/slack (similar to connectors/email)
• SlackConnector extending org.apache.manifoldcf.crawler.notifications.BaseNotificationConnector
• using Apache HTTP Client (is already a dependency in ManifoldCF) for HTTP Post
• gson jackson for creating the json request entity
• support markdown messages