On 1/31/2012 5:04 AM, Shing Wai Chan wrote:
> On 1/30/12 3:15 PM, Greg Wilkins wrote:
>>
>> currently the spec says in 6.2.1 - 4
>>
>> /The filter may invoke the next entity in the filter chain. The next
>> entity may be
>> another filter, or if the filter making the invocation is the last
>> filter configured in the
>> deployment descriptor for this chain, the next entity is the target
>> Web resource. The
>> invocation of the next entity is effected by calling the doFilter
>> method on the
>> FilterChain object, and passing in the request and response with
>> which it was
>> called or passing in wrapped versions it may have created.
>> The filter chain’s implementation of the doFilter method, provided by the
>> container, must locate the next entity in the filter chain and invoke
>> its doFilter
>> method, passing in the appropriate request and response objects.
>> /
>>
>>
>> This strongly indicates that it is the thread calling doFilter that
>> invokes the next element of the chain, be that a filter or
>> servlet. Also it is a very common pattern to use try{}finally{}
>> in filters to allocate and free resources, so it is essential to keep
>> the invocation chain intact.
>>
>> Thus if we clarify this, is must be to say:
>>
>> The service method is required to run in the same thread as all
>> filters that apply to the servlet.
> +1
Agree. +1
>>
>>
>> regards
>>
>>
>>
>>
>> On 31 January 2012 08:08, Shing Wai Chan <shing.wai.chan_at_oracle.com
>> <mailto:shing.wai.chan_at_oracle.com>> wrote:
>>
>> In an internal platform discussion, there is a question of
>> whether all filters need to be run in the same thread as in servlets.
>> In Section 6.2 of Servlet 3.0, there is a description on how
>> filters work.
>> There is "no" explicit requirement that the filters need to be
>> run in the same thread.
>> Is it a tacit assumption?
>>
>> We propose that the spec ought to say either:
>>
>> - The service method is required to run in the same thread as all
>> filters
>> that apply to the servlet.
>>
>> or
>>
>> - The service method is **not** required to run in the same
>> thread as filters
>> that apply to the servlet, and filters should not depend on
>> sharing
>> thread local data with the servlet.
>>
>>
>> Shing Wai Chan
>>
>>
>