[FLINK-3376] Add an illustration of Event Time and Watermarks to the docs

• Type: Improvement
• Status: Closed
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: 0.10.1
• Fix Version/s: 1.0.0
• Component/s: Documentation
• Assignee: Stephan Ewen
• Reporter: Stephan Ewen
• Created: 09/Feb/16 10:55
• Updated: 13/Apr/16 14:23
• Resolved: 13/Apr/16 14:23

Description

Users seem to get confused about how event time and watermarks work.
We need to add documentation with two sections:

1. Event time and watermark progress in general

• Watermarks are generated at the sources
• How Watermarks progress through the streaming data flow

2. Ways that users can generate watermarks

• EventTimeSourceFunctions
• AscendingTimestampExtractor
• TimestampExtractor general case