Message Acceptor
The message acceptor is a component responsible to receive the message from the Ingress adapter and store it into the database.
Message Metadata#
Along with the payload the message must contain metadata represented by the MessageMetadata. This metadata is extracted from the channel settings,
message payload and other sources. Usually the MessageMetadata instance can't be constructed at one place, so we supply the MessageMetaDataExtractorChain
consisting of MessageMetaDataSnippetExtractor instances. By doing so, every aspect of metadata extraction is put in it own class and the result of the
extraction is gathered in one MessageMetadata instance.
To simplify the construction of MessageMetaDataExtractorChain we supply several MessageMetaDataSnippetExtractor implementations:
ChannelConfigMessageMetaDataSnippetExtractor#
The ChannelConfigMessageMetaDataSnippetExtractor is responsible for reading metadata from the channel configuration. Usually, channel configuration parameters
like message encoding are extracted that way.
HeaderMessageMessageMetaDataSnippetExtractor#
The HeaderMessageMessageMetaDataSnippetExtractor is responsible for reading metadata from message headers. Most communication technologies support some concept
of message headers and the corresponding Ingress Adapter is mapping those headers to message headers used in the library. By doing so,
you can influence message attributes on a message level. For example, if you are receiving different types of messages by the same ingress adapter, this is
the easiest way to detect the type of the message.
Message filtering#
Sometimes, more messages are sent through the channel as needed to be received by the Ingress Adapter and needs to be accepted and stored by the library.
For this purpose, a special filtering component MessageFilter is configured in the MessageAcceptor. For more details, how to use the filter please check the Filtering messages section.
You can configure what messages it will support and filter the messages that will be delivered to the message acceptor.
Persisting Channel Message Acceptor#
To implement the inbox pattern, the message acceptor stores received messages in a persistent storage. For this purpose, the PersistingChannelMessageAcceptor
is implemented. For more details, please check the Message Persistence section.