On Wed, Jan 24, 2018 at 3:34 PM, Keerthika Mahendralingam <
[email protected]> wrote:

> Hi All,
>
> I need to get the cached response fetched time from origin server which is
> returned in the BE response with Date header. When I debugged the
> cache-mediator code, I found that when caching the response Date header is
> added to the cache. But when I retrieve the cached response for the
> subsequent request, Date header is removed from the cached response.
>
> This is due to we are removing the Date header from the response [1] and
> send a new Date header with the response to the user. If we set the
> preserveHeaders(in passthru-http.properties), I was able to get the Date
> header from the cached response as well.
>
> So, as I need the response fetched time to calculate the TTL value of the
> cached response, I am planning to add a property to the cached response to
> store the fetched time and use it to calculate the TTL. Or do we need to
> suggest the user to set the preserve header?
>
I think adding a property is better rather adding header to the response.

>
>
> [1]. https://github.com/wso2/wso2-synapse/blob/master/
> modules/transports/core/nhttp/src/main/java/org/apache/
> synapse/transport/passthru/util/PassThroughTransportUtils.java#L160
>
> Thanks,
> Keerthika.
>
> On Tue, Jan 23, 2018 at 8:26 PM, Keerthika Mahendralingam <
> [email protected]> wrote:
>
>> Hi All,
>>
>> I am trying to add an Age header when returning the cached response(as
>> discussed in [1]). I am following the steps as follows:
>>
>>    - If the response doesn't have the Date header, add Date header (with
>>    current time) when caching the response[2].
>>    - For the subsequent request, get the Date header value of the cached
>>    response, timeout and current requested time and find the TTL value as:
>>
>> TTL = difference ((DateHeaderValue + timeout), CurrentTime)
>>
>>
>>    - Set the TTL value as Age header.
>>
>> Please let me know if you have any concerns on this.
>>
>> [1]. [Architecture][RRT] Improving caching based on cache-control and
>> ETag headers
>> [2]. https://tools.ietf.org/html/rfc2616#page-124
>>
>> Thanks,
>> Keerthika.
>> --
>> <[email protected]>
>> Keerthika Mahendralingam
>> Software Engineer
>> Mobile :+94 (0) 776 121144 <+94%2077%20612%201144>
>> [email protected]
>> WSO2, Inc.
>> lean . enterprise . middleware
>>
>
>
>
> --
> <[email protected]>
> Keerthika Mahendralingam
> Software Engineer
> Mobile :+94 (0) 776 121144 <+94%2077%20612%201144>
> [email protected]
> WSO2, Inc.
> lean . enterprise . middleware
>



-- 
Harsha Kumara
Software Engineer, WSO2 Inc.
Mobile: +94775505618
Blog:harshcreationz.blogspot.com
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