Q: WLS 7 Cache Filters (Response Caching) Keys, Vars?

Question

          I can't seem to find any better docs about setting up cache filters than this
          http://edocs.bea.com/wls/docs70/servlet/progtasks.html#response_caching
          specifically, what are some examples of the init params, Keys and Vars?
          - especially in use with Servlets.
          Can Keys be Attribute names? Parameter names? Headers? Cookies? Other?
          And then what are examples of Vars?
          "variables calculated by the page that you want to cache"
          Does that really mean, it's cacheing a variable, like a resultset calculated in
          the doGet, instead of the page (response)? If so what can those be? Or should
          that have said "variables used to calculate the page"?
          Let's say I have a Servlet which might be called like
          myservlet?param1=A&param2=B&param3=C
          and there are a few cookies, cookie1=X;cookie2=Y;cookie3=Z
          In this case, only param1, param2, cookie1 can actually make a difference in the
          response. So I want my cached keyed off those (and only those).
          what would it look like?
          <init-param>
          <param-name>Key</param-name>
          <param-value>?</param-value>
          </init-param>
          <init-param>
          <param-name>Vars</param-name>
          <param-value>?</param-value>
          </init-param>
          

Answer 1

We are in process of updating the docs for cache filter. So they should be
          in
          better shape soon. Sorry for the inconvenience.
          Here is an example:
          <filter>
          <filter-name>CacheFilter</filter-name>
          <filter-class>weblogic.cache.filter.CacheFilter</filter-class>
          <init-param>
          <param-name>scope</param-name>
          <param-value>session</param-value>
          </init-param>
          <init-param>
          <param-name>timeout</param-name>
          <param-value>30m</param-value>
          </init-param>
          <init-param>
          <param-name>size</param-name>
          <param-value>10</param-value>
          </init-param>
          <init-param>
          <param-name>key</param-name>
          <param-value>parameter.userid,parameter.clientip</param-value>
          </init-param>
          <init-param>
          <param-name>vars</param-name>
          <param-value>request.var1,request.var2,request.var3</param-value>
          </init-param>
          </filter>
          <filter-mapping>
          <filter-name>CacheFilter</filter-name>
          <url-pattern>/cached/*</url-pattern>
          </filter-mapping>
          Various scopes:
          parameter -> request parameter
          request -> request attribute
          requestHeader -> request header
          responseHeader -> response header
          session -> http session
          application -> context
          cluster -> cluster scope (need to configure cluster listener for this)
          key:
          Syntax: Comma separated list of <scope>.<attribute name>
          Typically a given cache is identified by it's cache name that you configured
          in web.xml.
          If that's not specified the request uri is used as a cache name. But using
          keys you can
          specify additional values to identify a tag. For example if you want to
          separate out the
          cache for a given end user, then in addition to the cache name you can
          specify the keys
          as the userid, values for which you want to pick it up from the request
          parameter scope
          (query param/post params) plus perhaps a client ip. So you will specify your
          keys as:
          "parameter.userid,parameter.clientip"
          Here "parameter" is the scope (request parameter scope) and
          "userid"/"clientip" are the parameters/attributes.
          This means the primary key for the cache becomes the cache name (request uri
          in this
          case) + value of userid request param + value of clientip request param.
          Note: If you don't specify the scope the cache system will search all the
          scopes
          for the attribute.
          size:
          For caches that use keys, the size element defines the number of entries
          allowed.
          The default is an unlimited cache of keys. With a limited number of keys the
          tag
          uses a least-used system to order the cache (BubblingCache).
          vars:
          Same syntax as the key:
          Syntax: Comma separated list of <scope>.<attribute name>
          Variables are used to do input caching. So you can save the variables you
          used to calculate the cache. When the cache is retrieved the variables are
          restored back to the scope you specified. For example for retrieving results
          from
          a database you used var1 from request param, var2 from session etc. So
          when the cache is created the value of these variables are stored with the
          cache. When the cache is accessed next time these values are restored
          so you will be able to access them from respective scopes. For example
          var1 will be available from request and var2 from session.
          Hope this helps.
          --Vinod.
          "Stek" <[email protected]> wrote in message
          news:[email protected]...
          >
          > I can't seem to find any better docs about setting up cache filters than
          this
          >
          > http://edocs.bea.com/wls/docs70/servlet/progtasks.html#response_caching
          >
          > specifically, what are some examples of the init params, Keys and Vars?
          > - especially in use with Servlets.
          >
          > Can Keys be Attribute names? Parameter names? Headers? Cookies? Other?
          >
          > And then what are examples of Vars?
          > "variables calculated by the page that you want to cache"
          > Does that really mean, it's cacheing a variable, like a resultset
          calculated in
          > the doGet, instead of the page (response)? If so what can those be? Or
          should
          > that have said "variables used to calculate the page"?
          >
          > Let's say I have a Servlet which might be called like
          > myservlet?param1=A&param2=B&param3=C
          > and there are a few cookies, cookie1=X;cookie2=Y;cookie3=Z
          >
          > In this case, only param1, param2, cookie1 can actually make a difference
          in the
          > response. So I want my cached keyed off those (and only those).
          >
          > what would it look like?
          >
          > <init-param>
          > <param-name>Key</param-name>
          > <param-value>?</param-value>
          > </init-param>
          > <init-param>
          > <param-name>Vars</param-name>
          > <param-value>?</param-value>
          > </init-param>
          >