[jira] [Commented] (SCB-1929) provide new mechanism: Filter

["Willem Jiang (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SCB-1929?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17114481#comment-17114481 ] 

Willem Jiang commented on SCB-1929:
-----------------------------------

How can we unify the different handler or filter into one  new Filter?
If we want to assemble them together, how can I define the invocation priority of the new Filter?


> provide new mechanism: Filter
> -----------------------------
>
>                 Key: SCB-1929
>                 URL: https://issues.apache.org/jira/browse/SCB-1929
>             Project: Apache ServiceComb
>          Issue Type: New Feature
>          Components: Java-Chassis
>            Reporter: Jimin Wu
>            Assignee: Jimin Wu
>            Priority: Major
>             Fix For: java-chassis-2.1.0
>
>
> currently, we have extensions:
>  # HttpClientFilter
>  # HttpServerFilter
>  # Handler
>  # ProducerInvokeExtension
> and we hard code to invoke all the extensions:
>  # consumer:
>  ## invoke all handlers
>  ## invoke all HttpClientFilters
>  # producer:
>  ## schedule to operation related executor
>  ## invoke all HttpServerFilters
>  ## invoke all handlers
> PROBLEMS:
>  # all these extensions are about invocation, just have different prototype
>  # for consumer
>  ## when a sync invocation failed, and want to retry, retry schedule is conflict to sync mechanism
>  # for producer
>  ## qps-limiter should invoke before schedule, currently we hard code it
>  ## if want to write reactive extension before schedule, to not care for controller method is sync or async, currently can not do it
>  ## if executor is a real thread pool, and a reactive extension after schedule will break thread schedule plan, that maybe will cause block event loop
>  # exception convert only avaiable for controller method invoke, but all extensions exception need convert too
> SOLUTION:
> provide new mechanism: Filter, to unify all the extensions, and change main invocation process flow from hard code to by configuration
>  # prototype:
> {code:java}
> public @interface FilterMeta {
>   String name();
>   /**
>    *
>    * @return null for all transport
>    */
>   String transport();
>   /**
>    *
>    * @return true to use same instance for each filter chain
>    */
>   boolean shareable() default true;
> }
> public interface Filter {
>   CompletableFuture<Response> onFilter(Invocation invocation, FilterNode nextNode);
> }
> {code}
>  # configuration
> {code:java}
> servicecomb:
>   filter-chains:
>     defines:
>       consumer-v1: consumer-handlers, http-client-filters
>       producer-v1: schedule, http-server-filters, producer-handlers
>       consumer-v2: simple-load-balance
>       producer-v2: schedule
>     default-consumer: $consumer-v2
>     default-producer: $producer-v2
>     consumers:
>       ms-1: simple-retry, load-balance
>     producers:
>       ms-2: qps-limiter, $producer-v2
> {code}
>  ## free to pre-define multiple chains
>  ## reference pre-define chain, and combine to new chain
>  ## microservice scope chain
>  ## schema or operation scope chain, if have requirements in the future
>  # invoke exception converter when throwing a exception for all filter
> COMPATIBLE:
>  # wrap old HttpClientFilters to a Filter
>  # wrap old HttpServerFilters to a Filter
>  # wrap old consumer handlers to a Filter
>  # wrap old producer handlers to a Filter
>  # pre-define old filter chains, and default to old chains



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