CODEWITHSUNDEEP
javaspringspring-integration
pnescior
pnescior

Reputation: 136

What's the purpose of automatically added bridge component after router?

After visualizing my flow (using this great project, btw.), I've noticed that there are bridge components (together with DirectChannels) inserted right after my router:

flow visualization

My DSL configuration:

.route(Message.class, messageTypeHeader(), mapping -> mapping
    .id("filteringRouterEndpoint")
    .resolutionRequired(false)
    .defaultSubFlowMapping(rejectedByFiltersFlow)
    .subFlowMapping(MessageType.TYPE_1, s -> s
            .channel("type1MappingChannel")
            .filter(type1MappingFilter)
            .channel(ACCEPTED_BY_FILTERS_CHANNEL_NAME))
    .subFlowMapping(MessageType.TYPE_2, s -> s
            .channel("type2MappingChannel")
            .filter(type2MappingFilter)
            .channel(ACCEPTED_BY_FILTERS_CHANNEL_NAME))
    .subFlowMapping(MessageType.TYPE_3, s -> s
            .channel("type3MappingChannel")
            .filter(type3MappingFilter)
            .channel(ACCEPTED_BY_FILTERS_CHANNEL_NAME)))

(some names are different than on the flow, just to simplify)

I've noticed, that if I don't specify the channels explicitly on the beginning of the mapping subflows (i.e. typeXMappingChannels), then the bridges aren't created: flow visualization 2

but I want to specify channels by myself, just to know their exact name, or to have other than DirectChannel implementation for example.

What is the reason for that? Or maybe I made something wrong in my configuration?

Upvotes: 2

Views: 82

Answers (1)

Gary Russell
Gary Russell

Reputation: 174719

It's an artifact of how the flow is constructed.

When we call .subflowMapping() we start to build a flow that begins with a channel. Since we haven't encountered the first element of the flow yet .channel() in your case, we build a default input channel.

Then, when we encounter the .channel() we see the previous component is a channel, so we bridge it.

We could possibly optimize it out for this specific case; I'll take a look, but it will likely be a 5.2 change if we do it.

GH-2890

Upvotes: 1

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