Wowza Community

Wowza does not set last-modified header

We’re attempting to use an Akamai Progressive Media Download and HTTP Origin mode to serve up Smooth Streaming VOD assets.

I’ve enabled HTTP Origin mode and added the Cache-Control headers. That is good, but we’ll also need Wowza to return last modified headers, and to properly respond with 304 if the client includes if-modified-since headers.

I couldn’t find this being requested elsewhere, which I find curious, as I would think this is a common request for people using a CDN w/ Wowza HTTP Origin.

I don’t think this can work. Wowza is supplying chunks to a CDN cache, clients are consuming those chunks. Wowza is not aware of the client. What do you expect to happen?

Richard

Bob,

I will forward your request.

Richard

I guess I expected Wowza to know if the source files have changed or not. Though I do understand that since Wowza is producing the chunks on the fly each time, that technically those chunks would always be new. But we also tried MediaCache, where that data is sitting there in the cache, but that doesn’t produce last modified headers either.

I’ll confer with Akamai some more to see if there are workarounds and if it’s really necessary

Richard, I thought some more about this. Akamai appears to rely on the origin’s ability to properly respond to “If-Modified-Since” headers to determine if content has changed or not. Wowza would need to be able to properly determine if the content has changed or not. If it hasn’t it would return a 304 w/o any content body. Otherwise it would return a 200 with the normal payload.

Here is what an Akamai engineer told me

we rely on the last modified headers if the end users machine sends a “if modified since” requests then a child server might send the same request to a parent server as well and if the content does not have last modified header then it might lead us to come to the origin every time with a GET request and receive a 200 resp with some payload …if wowza sends a 304 then there would not be any payload ( you save up on your monthly bandwidth usage )

Does that make sense?

I would be interested to know, if any steps are actually planned in this direction. https://www.wowza.com/docs/scaling-with-wowza-http-origin-applications states that:

-Some 3rd-party CDNs such as Akamai or EdgeCast can connect to Wowza Streaming Engine applications running in HTTP Origin mode and re-stream the content.

-The CDN ensures that everything is cached and load-balanced properly.

However, due to Wowza Streaming Engine not responding to Akamai’s If-Modified-Since HTTP header (tested the last time with version 4.3 and no mention of this functionality in release notes for 4.4 and 4.5), the caching part in above statement is not in Akamai’s case completely true.

Hello,

Are you stating that the cache control settings form this article:

https://www.wowza.com/docs/how-to-configure-a-wowza-server-as-an-http-caching-origin

Would these options not give you the control of changes that you are looking for as far as keeping the Caching edge properly updated?

This case may be better handled in a ticket where we can go over in greater detail your use case and work one on one with you to help get you to a solution for your needs.

We can then return to this thread and post a solution after going over this in greater detail.

Regards,

Jason Hatchett