如何在QuickFix中创建Socket Initiator实例时避免使用MessageStoreFactory

Hey there! Great question—yes, you absolutely can skip creating a persistent MessageStoreFactory when setting up a QuickFix Socket Initiator, and there are two practical approaches depending on your use case. Let’s break them down:

1. Implement a "No-Op" Null Message Store (For Zero State Persistence) #

If your use case doesn’t require retaining session state (like sequence numbers) between restarts—say, for testing, one-off sessions, or if you’re managing sequence numbers entirely on your own—you can create a custom MessageStore and MessageStoreFactory that do nothing.

Here’s a Java example of the no-op store:

public class NullMessageStore implements MessageStore {
    // All methods are empty or return default values
    @Override public void setNextSenderSeqNum(int next) {}
    @Override public void setNextTargetSeqNum(int next) {}
    @Override public int getNextSenderSeqNum() { return 1; }
    @Override public int getNextTargetSeqNum() { return 1; }
    @Override public void incrementNextSenderSeqNum() {}
    @Override public void incrementNextTargetSeqNum() {}
    @Override public void reset() {}
    @Override public void refresh() {}
    @Override public void persist(Message message) {}
    @Override public void persist(int seqNum, String msg) {}
    @Override public boolean set(int seqNum, String msg) { return true; }
    @Override public String get(int seqNum) { return null; }
    @Override public void delete(int seqNum) {}
    @Override public void start() {}
    @Override public void stop() {}
    @Override public void destroy() {}
}

Then the corresponding factory:

public class NullMessageStoreFactory implements MessageStoreFactory {
    @Override public MessageStore create(SessionID sessionID) {
        return new NullMessageStore();
    }
}

Use it when initializing your Socket Initiator:

SocketInitiator initiator = new SocketInitiator(
    yourApplicationInstance,
    new NullMessageStoreFactory(), // No persistent storage here
    yourSessionSettings,
    new DefaultLogFactory(yourSessionSettings),
    new DefaultMessageFactory()
);

This setup will always start sequence numbers at 1 on every restart and won’t save any message history.

2. Use QuickFix’s Built-In Memory Store (For Temporary In-Memory State) #

If you need to retain session state during the runtime of your application (but don’t want to persist it to disk), QuickFix provides a MemoryStoreFactory in most implementations. This stores sequence numbers and message history in RAM—no file system required.

Here’s how to use it:

SocketInitiator initiator = new SocketInitiator(
    yourApplicationInstance,
    new MemoryStoreFactory(), // In-memory only, no disk I/O
    yourSessionSettings,
    new DefaultLogFactory(yourSessionSettings),
    new DefaultMessageFactory()
);

Unlike the null store, this will keep track of sequence numbers while your application is running. The state is lost once the app restarts, though.

Important Caveats #

• Don’t use these in production if you need message durability: If your application crashes or restarts, the null store will reset sequence numbers to 1, which can lead to message rejection or duplicate processing by the counterparty.
• Check your QuickFix version: Some older versions might not have MemoryStoreFactory built-in, so you’ll need to fall back to the custom null store.

内容的提问来源于stack exchange，提问作者sr123