A channel behaves differently depending on which direction it's attached to a feed with. The connector type stays the same — only the direction of the attachment determines how mapping and sync work.
Input channels
An input channel (in) reads
records from the external source and merges them into the feed's products. Its mappings run source column →
canonical field: from is the
column detected in the source data, and to
is the canonical field it should populate. Each product's raw incoming values are kept as its source data for
reference.
Output channels
An output channel (out) takes
the feed's products and delivers them to the external destination. Its mappings run the other way — canonical
field → destination field: from
is the canonical field, and to
is the attribute name the destination expects (defaulting to the Google Merchant Center spec name, e.g.
identifier →
id).
Both directions on one feed
Because direction lives on the attachment (not the channel), a single feed commonly has one or more input channels building the catalog and several output channels distributing it — for example, importing from Shopify while exporting to Google Merchant Center, Meta, and a comparison shopping engine, each with its own mapping and sync schedule.
Feed-to-feed chaining
The feed-to-feed connector lets one feed's output become another feed's input, which is useful for building a filtered or re-mapped sub-feed (for example, a region- or category-specific feed) from a larger master feed without duplicating the source connection.