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Dispatcher Configuration to Cache Servlet Requests

pavanr6387218
Level 2
Level 2

Hi,

We have a requirement where in  we want to cache the servlet(AEM) response.

Servlet is making a REST call to third party to fetch a response which is constant(response remains same)

Response of the servlet to be cached:

Servlet :  /bin/servletpathname?queryParam=apiurl.

From clientside, we are making an ajax call to /bin/servletpathaname/apiurl/a.html (a.html is being appended so that the request has an extension.).

At Dispatcher We

are using internal redirect to redirect /bin/servletpathaname/apiurl/a.html  to /bin/servletpathname?queryParam=apiurl.

We are able to get a successful response back from servlet (Internal Redirect is successful). But at dispatcher we observe that the request is not getting cached.

Am I missing something?

I want to understand how can we cache the servlet response, this would greatly reduce the load on the end server and improve performance.

Dispatcher:

  • The request is a GET request
  • We have appended extension for the primary request.
  • No Query Param in the initial request
  • There is no authorization.

Dispatcher.any:

/rules
  {
    /0000  {  /glob "*"   /type "allow" }
  }
0 Replies
Andrew_Khoury
Employee
Employee

> At Dispatcher We are using internal redirect to redirect /bin/servletpathaname/apiurl/a.html  to /bin/servletpathname?queryParam=apiurl.

That will not make the request cacheable unfortunately, dispatcher will not cache 301 or 302 redirects or requests that it must send with a querystring.  Even though you are rewriting this or redirecting this at the Apache level you cannot cache it in dispatcher unless you create a mapping in AEM that maps from /bin/servletpathaname/apiurl/a.html  to /bin/servletpathname?queryParam=apiurl.  Alternatively, you could cache these requests at the CDN level.  Many CDNs do allow caching of requests with querystrings.

Andrew_Khoury
Employee
Employee

Note: The request received by Apache here is the /bin/servletpathaname/apiurl/a.html one, but the request being received and sent by the dispatcher module within apache has the querystring: /bin/servletpathname?queryParam=apiurl

pavanr6387218
Level 2
Level 2

I will try implementing resourcemapping and validate if dispatcher caches the request.

smacdonald2008
Level 10
Level 10

Just a general question here - does your servlet return static values. If it returns dynamic values that change each time (ie - return weather data that changes) - why would you cache it?

pavanr6387218
Level 2
Level 2

We are fetching articles from 3rd party system via REST API calls. The frequency of this content getting modified is very less. Within AEM, content author would then author the component with the Article API call. This API is forwarded to dispatcher as apiurl in below url.

/bin/servletpathaname/apiurl/a.html. We have a rewrite rule at dispatcher to send the servlet as /bin/servletpathname?queryParam=apiurl. Servlet would then make the call to thirdparty system( we are trying to minimize these calls)

When an enduser hits the page, if we have the servlet response cached we can render that from dispatcher instead of hitting third party system( they have concerns over the traffic to their system).

smacdonald2008
Level 10
Level 10

If the Data changes from the Servlet - will the data be updated in the component or will old cached data still be displayed?  Is that a concern here?

pavanr6387218
Level 2
Level 2

If the article changes(data changes from servlet changes), We are exposing another servlet which will be used to invalidate the cache.

VitthalaShiva
Level 2
Level 2

Can u create a servlet with the resouceType instead of path.

This will help u to cache the request on dispatcher and also just create a nide under /etc whose resource type will be ur servlet.

Let me know if this works.

pavanr6387218
Level 2
Level 2

Resoruce Type would not be an option as the apiurl will be authored.

pavankumarn993
Level 1
Level 1

Hi , Since in your case getting the same response always ,

Instead of using query params, you can also try selectors like /bin/servletpathaname/a.apiurl.html in Ajax call. Later you can read this selector in servlet , by this you can cache the response.

vikask76191633
Level 1
Level 1

Is this question answered ? As I am also trying to do something similar however I am trying to cache service response.

URL: domain:port/services/servicename/apiname

This URL is a calls AEM servlet internally using httpclient and bring tons of data in json format, (static data).  Since it is taking a minute or more to return the response, I want to cache it at dispatcher.

How I can proceed with ?

Regards

Vikas