Hi Keerthika, We should have an option for disregarding the cache-control headers and the default value should be that the cache-control headers be disregarded. This is because the current cache mediator is written so that it is fully backward compatible with the older versions of the cache mediators. Any one using cache mediator in a synape configuration in an older version can use the same synapse configuration in the new version and can expect the same behavior. If he/she wants to make use of the new features he/she may do so by editing the synapse configurations.
Thanks, Riyafa On Fri, Jan 12, 2018 at 12:24 PM, Keerthika Mahendralingam < [email protected]> wrote: > Thanks Isuru. Will check the existing functionality. > > @Vijitha, > +1 for providing the configuration option for omitting the cache-control > headers. > > @Sanjeewa > Will check with the latest cache mediator. > > Thanks, > Keerthika. > > On Fri, Jan 12, 2018 at 12:16 PM, Vijitha Ekanayake <[email protected]> > wrote: > >> Hi Sanjeewa, >> >> >> On Fri, Jan 12, 2018 at 12:01 PM, Sanjeewa Malalgoda <[email protected]> >> wrote: >> >>> So i think we can add latest cache mediator dependency to API Manager >>> 2.2.0 branch and test this feature. >>> If there are any gaps in documents or implementation we will be able to >>> fix them and officially support this feature from 2.2.0 onward. >>> WDYT? >>> >> >> +1 for this approach. >> >>> >>> @Vijitha, Cache mediator can engage per API basis. So if someone do not >>> interested on caching they can simply remove cache mediator for that >>> particular mediation flow. >>> >> >> I intended to state just an option of disregarding the HTTP caching >> however not the response caching. Shouldn't it be valuable to have a design >> alternative to disregard the HTTP Caching yet not the default response >> caching? >> >> Thanks. >> >>> >>> Thanks, >>> Sanjeewa. >>> >>> On Fri, Jan 12, 2018 at 11:07 AM, Isuru Udana <[email protected]> wrote: >>> >>>> Hi Keerthika, >>>> >>>> ETag caching support is already implemented at the http transport >>>> level. >>>> This feature was introduced long time ago but still the documentation >>>> is not added to the wiki. >>>> Please refer to following jiras for more information. >>>> >>>> >>>> https://wso2.org/jira/browse/ESBJAVA-3504 >>>> >>>> https://wso2.org/jira/browse/DOCUMENTATION-1435 >>>> >>>> >>>> Thanks. >>>> >>>> >>>> On Fri, Jan 12, 2018 at 10:51 AM, Keerthika Mahendralingam < >>>> [email protected]> wrote: >>>> >>>>> Hi Shazni, >>>>> >>>>> Please find the answers inline. >>>>> >>>>>> >>>>>> 1. Does the user specify whether the ETag header should present in >>>>>> the response or not? Or is it always available if the cache mediator is >>>>>> used? >>>>>> >>>>> If the backend returns the response with ETag header, cahce mediator >>>>> always need to validate the response before sending the cached response to >>>>> the user. >>>>> >>>>>> >>>>>>> - If it is available and ETag is present in the cached response, >>>>>>> make a request with "If-None-Match" header with the ETag value. >>>>>>> >>>>>>> >>>>>>> - If the server returns "304 Not Modified" response returns the >>>>>>> cached response to the user. >>>>>>> >>>>>>> 2. If the caller makes a request with "If-None-Match" header with >>>>>> the ETag value and if it matched, why would you need to respond with the >>>>>> cached message. Shouldn't it be only 304 with empty message as the >>>>>> response >>>>>> hasn't changed? >>>>>> >>>>> I considered only the use case where the backend server response has >>>>> the ETag header. But we need to consider the request as well. As you said, >>>>> if the user sends a request with "If-None-Match" header with the ETag >>>>> value and if it is matched with the cached response ETag value, then we >>>>> need to send 304 response. If it is not matched, cache mediator should >>>>> validate the cached response with the backend and return the response to >>>>> the user. Thanks for pointing this out. >>>>> >>>>>> >>>>>> >>>>>>> *Honor "max-age" cache-control header*If the "max-age" header >>>>>>> presents in the response it specifies the maximum time in seconds that >>>>>>> the >>>>>>> fetched response is allowed to be reused from the time of the request. >>>>>>> So >>>>>>> the response should be cached and reused within the max-age time limit. >>>>>>> So >>>>>>> the Cache mediator should honor max-age instead of timeout >>>>>>> configuration if >>>>>>> it is less than the timeout configuration. >>>>>> >>>>>> >>>>>> 3. What is the behavior when the timeout configuration is less than >>>>>> the max-age cache-control header? >>>>>> >>>>> Cached response expires after the timeout limit. >>>>> >>>>> Thanks, >>>>> Keerthika. >>>>> >>>>>> >>>>>> On Thu, Jan 11, 2018 at 3:20 AM, Keerthika Mahendralingam < >>>>>> [email protected]> wrote: >>>>>> >>>>>>> Hi All, >>>>>>> >>>>>>> In the current cache mediator implementation, cache control headers >>>>>>> and ETag haven't been considered when serving responses through the >>>>>>> cache >>>>>>> mediator. Basically, it caches all responses and responds with same >>>>>>> headers >>>>>>> for the subsequent requests. I am planning to improve the current cache >>>>>>> mediator with the following features: >>>>>>> >>>>>>> - Honor ETag header >>>>>>> - Honor "no-cache" & "no-store" cache-control header. >>>>>>> - Honor "max-age" cache-control header. >>>>>>> - Add Age header based on "max-age" cache-control header when >>>>>>> returning the cached response. >>>>>>> >>>>>>> >>>>>>> *1. ETag support:* >>>>>>> If ETag header is present in the response, subsequent requests need >>>>>>> to be issued with the "If-None-Match" header(with ETag value) and if the >>>>>>> requested resource is modified from the last response fetched time, a >>>>>>> new >>>>>>> modified response will be returned with new ETag. And this new response >>>>>>> needs to be cached. If it is not modified, the server returns a "304 Not >>>>>>> Modified" response. In that case, the cached response can be reused. >>>>>>> >>>>>>> Flow: >>>>>>> >>>>>>> - Cache mediator receives a request. >>>>>>> - Check whether a cached response is available for the same >>>>>>> request. >>>>>>> - If it is available and ETag is present in the cached response, >>>>>>> make a request with "If-None-Match" header with the ETag value. >>>>>>> - If the server returns "304 Not Modified" response returns the >>>>>>> cached response to the user. >>>>>>> - If the server returns a new modified response(200 OK response) >>>>>>> then cache the newly returned response. >>>>>>> >>>>>>> >>>>>>> *2. Honor "no-cache" and "no-store" header* >>>>>>> >>>>>>> - If the "no-cache" header is present in the response it >>>>>>> indicates that the returned response can’t be used to satisfy a >>>>>>> subsequent >>>>>>> request to the same URL without first checking with the server if the >>>>>>> response has changed. So before responding with the cached response >>>>>>> cache >>>>>>> mediator should validate the response with ETag. This can be >>>>>>> supported >>>>>>> through the ETag support. >>>>>>> - If the "no-store" header is present in the response, Cache >>>>>>> mediator should not cache the returned response. >>>>>>> >>>>>>> *3. Honor "max-age" cache-control header* >>>>>>> If the "max-age" header presents in the response it specifies the >>>>>>> maximum time in seconds that the fetched response is allowed to be >>>>>>> reused >>>>>>> from the time of the request. So the response should be cached and >>>>>>> reused >>>>>>> within the max-age time limit. So the Cache mediator should honor >>>>>>> max-age >>>>>>> instead of timeout configuration if it is less than the timeout >>>>>>> configuration. >>>>>>> >>>>>>> 4. *Include an ‘Age’ header with the response* >>>>>>> Cache mediator should return the true TTL value of a response >>>>>>> without altering the value of the cache-control max-age header returned >>>>>>> by >>>>>>> the back-end. >>>>>>> >>>>>>> >>>>>>> Flow: >>>>>>> >>>>>>> - Calculate the TTL using response fetched time and max-age >>>>>>> header >>>>>>> - Set the Age header to the cached response before returning it >>>>>>> to the user. >>>>>>> >>>>>>> >>>>>>> [1]. https://developers.google.com/web/fundamentals/performa >>>>>>> nce/optimizing-content-efficiency/http-caching >>>>>>> [2]. https://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html >>>>>>> >>>>>>> Thanks, >>>>>>> Keerthika. >>>>>>> -- >>>>>>> <[email protected]> >>>>>>> Keerthika Mahendralingam >>>>>>> Software Engineer >>>>>>> Mobile :+94 (0) 776 121144 <+94%2077%20612%201144> >>>>>>> [email protected] >>>>>>> WSO2, Inc. >>>>>>> lean . enterprise . middleware >>>>>>> >>>>>> >>>>>> >>>>>> >>>>>> -- >>>>>> Shazni Nazeer >>>>>> >>>>>> Mob : +94 777737331 >>>>>> LinkedIn : http://lk.linkedin.com/in/shazninazeer >>>>>> >>>>>> Blogs : >>>>>> >>>>>> https://medium.com/@mshazninazeer >>>>>> http://shazninazeer.blogspot.com >>>>>> >>>>>> <http://wso2.com/signature> >>>>>> >>>>> >>>>> >>>>> >>>>> -- >>>>> <[email protected]> >>>>> Keerthika Mahendralingam >>>>> Software Engineer >>>>> Mobile :+94 (0) 776 121144 <+94%2077%20612%201144> >>>>> [email protected] >>>>> WSO2, Inc. >>>>> lean . enterprise . middleware >>>>> >>>> >>>> >>>> >>>> -- >>>> *Isuru Udana* >>>> Senior Technical Lead >>>> WSO2 Inc.; http://wso2.com >>>> email: [email protected] cell: +94 77 3791887 <077%20379%201887> >>>> blog: http://mytecheye.blogspot.com/ >>>> >>> >>> >>> >>> -- >>> >>> *Sanjeewa Malalgoda* >>> WSO2 Inc. >>> Mobile : +94713068779 <+94%2071%20306%208779> >>> >>> <http://sanjeewamalalgoda.blogspot.com/>blog >>> :http://sanjeewamalalgoda.blogspot.com/ >>> <http://sanjeewamalalgoda.blogspot.com/> >>> >>> >>> >> >> >> -- >> Vijitha Ekanayake >> Senior Software Engineer*, *WSO2, Inc.; http://wso2.com/ >> Mobile : +94 777 24 73 39 | +94 718 74 44 08 >> 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 > -- Riyafa Abdul Hameed Software Engineer, WSO2 Lanka (Pvt) Ltd <http://wso2.com/> Email: [email protected] <[email protected]> Website: https://riyafa.wordpress.com/ <http://riyafa.wordpress.com/> <http://facebook.com/riyafa.ahf> <http://lk.linkedin.com/in/riyafa> <http://twitter.com/Riyafa1>
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