de.otto.synapse.messagestore

Interface MessageStore

All Superinterfaces:

java.lang.AutoCloseable

All Known Subinterfaces:

SnapshotMessageStore

All Known Implementing Classes:

DelegatingSnapshotMessageStore, OffHeapIndexingMessageStore, OnHeapCompactingMessageStore, OnHeapIndexingMessageStore, OnHeapRingBufferMessageStore

public interface MessageStore
extends java.lang.AutoCloseable

A repository used to store and retrieve Messages in their insertion order.

When using a Message Store, we can take advantage of the asynchronous nature of a messaging infrastructure. When we send a message to a channel, we send a duplicate of the message to a special channel to be collected by the Message Store.

This can be performed by the component itself or we can insert a Wire Tap into the channel. We can consider the secondary channel that carries a copy of the message as part of the Control Bus. Sending a second message in a 'fire-and-forget' mode will not slow down the flow of the main application messages. It does, however, increase network traffic. That's why we may not store the complete message, but just a few of fields that are required for later analysis, such as a message ID, or the channel on which the message was sent and a timestamp.

See Also:

EIP: Message Store

Method Summary

Modifier and Type	Method and Description
void	add(MessageStoreEntry entry) Appends the specified element to the end of this list (optional operation).
default void	close()
java.util.Set<java.lang.String>	getChannelNames() Returns a set containing the channel names of the messages contained in the MessageStore
com.google.common.collect.ImmutableSet<Index>	getIndexes()
default ChannelPosition	getLatestChannelPosition() Deprecated.
ChannelPosition	getLatestChannelPosition(java.lang.String channelName) Returns the latest ChannelPosition of the given channel, derived from the messages contained in this MessageStore.
default boolean	isCompacting()
default long	size() Returns the number of messages contained in the MessageStore.
java.util.stream.Stream<MessageStoreEntry>	stream() Returns a Stream of all entries contained in the MessageStore.
java.util.stream.Stream<MessageStoreEntry>	stream(Index index, java.lang.String value) Returns a Stream of all entries contained in the MessageStore that have are matching the given Index value (optional operation).

Method Detail

getChannelNames

java.util.Set<java.lang.String> getChannelNames()

Returns a set containing the channel names of the messages contained in the MessageStore

Returns:

set of channel names

getIndexes

com.google.common.collect.ImmutableSet<Index> getIndexes()

getLatestChannelPosition

ChannelPosition getLatestChannelPosition(java.lang.String channelName)

Returns the latest ChannelPosition of the given channel, derived from the messages contained in this MessageStore.

The position is calculated by merging the optional positions of the messages.

Messages without positions will not change the latest ChannelPosition. If no message contains position information, the returned ChannelPosition is ChannelPosition.fromHorizon()

Parameters:

channelName - the name of the channel

Returns:

ChannelPosition

getLatestChannelPosition

@Deprecated
default ChannelPosition getLatestChannelPosition()

Deprecated.

stream

java.util.stream.Stream<MessageStoreEntry> stream()

Returns a Stream of all entries contained in the MessageStore.

The stream will maintain the insertion order of the entries.

Returns:

Stream of entries

stream

@Beta
java.util.stream.Stream<MessageStoreEntry> stream(Index index,
                                                        java.lang.String value)

Returns a Stream of all entries contained in the MessageStore that have are matching the given Index value (optional operation).

The stream will maintain the insertion order of the entries.

Parameters:

index - the Index

value - the value identifying the requested messages in the specified index

Returns:

stream of message-store entries matching the index or emptyStream, if the index is not known, or if there are no entries

Throws:

java.lang.UnsupportedOperationException - if the stream(Index,String) operation is not supported by this store

add

void add(@Nonnull
         MessageStoreEntry entry)

Appends the specified element to the end of this list (optional operation).

MessageStores that support this operation may place limitations on what elements may be added to this list. In particular, some stores will refuse to add entries for more than a single channel. MessageStore classes should clearly specify in their documentation any restrictions on what elements may be added.

Parameters:

entry - element to be appended to this message store

Throws:

java.lang.UnsupportedOperationException - if the add operation is not supported by this store

java.lang.NullPointerException - if the specified element is null

java.lang.IllegalArgumentException - if some property of this element prevents it from being added to this list

size

default long size()

Returns the number of messages contained in the MessageStore.

Primarily used for testing purposes. If the MessageStore can not implement this without major performance impacts (like, for example, having to download and parse huge files from S3), the method is not required to be implemented.

Returns:

number of messages

close

default void close()

Specified by:

close in interface java.lang.AutoCloseable

isCompacting

default boolean isCompacting()