Configuring a Transaction Log

Before demonstrating the power of the transaction log, we will first show how to configure the transaction log in the AMPS configuration file.

<!-- All transaction log definitions are contained within the TransactionLog block.
    The following global settings apply to all Topic blocks defined within the
    TransactionLog: JournalDirectory, PreallocatedJournalFiles, and JournalSize. -->
<TransactionLog>

    <!-- The JournalDirectory is the filesystem location where journal files and journal
        index files will be stored. -->
    <JournalDirectory>./amps/journal/</JournalDirectory>

    <!-- The JournalArchiveDirectory is the filesystem location to which AMPS will
        archive journals. Notice that AMPS does not archive files by default. You
        configure an action to archive journal files -->
    <JournalArchiveDirectory>/mnt/somedev0/amps/journal</JournalArchiveDirectory>

    <!-- PreallocatedJournalFiles defines the number of journal files AMPS will create as
        part of the server startup. Default: 2 Minimum: 1 -->
    <PreallocatedJournalFiles>1</PreallocatedJournalFiles>

    <!-- The JournalSize is the approximate size of the journal files
         that AMPS will create. -->

    <JournalSize>10MB</JournalSize> <!-- Suitable for development work on
                                         a local development system.
                                         A production deployment would
                                         typically use 250MB to 2GB
                                         depending on message size,
                                         message volume
                                         and retention policy. -->

    <!-- When a Topic is specified, then all messages which match exactly the specified
        topic or regular expression will be included in the transaction log. Otherwise,
        AMPS initializes the transaction logging, but does not record any messages to
        the transaction log. -->
    <Topic>
        <Name>orders</Name>
        <MessageType>nvfix</MessageType>
    </Topic>

</TransactionLog>