You can try Striim (shameless plug, I work there). You build all your stream processing pipelines in a simple, SQL-like language in a nice web-based UI. It also has built in adapters to convert log data, JSON, XML, database change capture, and other complex data formats into in-memory streams.

The product also comes with dashboards so you can do ad-hoc analytics and data visualization on your streams and windows.

It has support for stream replay built on top of Kafka-backed persistent streams. It has a commercial license, but we're pretty flexible with startups

http://www.striim.com/download-striim/