org.fcrepo.server.journal
Class JournalWriter

java.lang.Object
  org.fcrepo.server.journal.xmlhelpers.AbstractXmlWriter
      org.fcrepo.server.journal.JournalWriter

All Implemented Interfaces:

JournalConstants

Direct Known Subclasses:

MulticastJournalWriter, MultiFileJournalWriter, SingleFileJournalWriter

public abstract class JournalWriter
extends AbstractXmlWriter

The abstract base for all JournalWriter classes.

Each child class is responsible for providing an XMLEventWriter that will receive the JournalEntry tag. This class will format a JournalEntry object into XML and add it to the XMLEventWriter.

Note that the writing of an entry is necessarily a three step process, consisting of

1. calling prepareToWriteJournalEntry(),
2. invoking the management method,
3. calling writeJournalEntry(CreatorJournalEntry)

Several factors combine to require this sequence.

• Each new journal file starts with a repository hash.
• Repository hashes are expensive to calculate (on the order of 10 seconds). We don't want to calculate a hash unless it is needed for a new journal file.
• We cannot predict in advance which journal entry will require that a new journal file be opened. The preceding file may be closed asynchronously as a result of a period of inactivity.
• The repository hash must be calculated before the management method is invoked, so the receiver can confirm the file before making any changes to its own repository.
• The journal entry must be written after the management method is invoked. The management method may add values to the context object in the CreatorJournalEntry, and these values must be written to the journal.

Author:

Jim Blake

Field Summary

protected Map<String,String>	parameters
protected String	role
protected ServerInterface	server
static Object	SYNCHRONIZER A single object on which to synchronize all writing operations.

Fields inherited from interface org.fcrepo.server.journal.JournalConstants

ARGUMENT_NAME_ALT_IDS, ARGUMENT_NAME_CHECKSUM, ARGUMENT_NAME_CHECKSUM_TYPE, ARGUMENT_NAME_CONTEXT, ARGUMENT_NAME_CONTROL_GROUP, ARGUMENT_NAME_DATATYPE, ARGUMENT_NAME_DISSEMINATOR_ID, ARGUMENT_NAME_DISSEMINATOR_LABEL, ARGUMENT_NAME_DISSEMINATOR_STATE, ARGUMENT_NAME_DS_CONTENT, ARGUMENT_NAME_DS_ID, ARGUMENT_NAME_DS_LABEL, ARGUMENT_NAME_DS_LOCATION, ARGUMENT_NAME_DS_STATE, ARGUMENT_NAME_ENCODING, ARGUMENT_NAME_END_DATE, ARGUMENT_NAME_FORCE, ARGUMENT_NAME_FORMAT, ARGUMENT_NAME_FORMAT_URI, ARGUMENT_NAME_IN, ARGUMENT_NAME_IS_LITERAL, ARGUMENT_NAME_LABEL, ARGUMENT_NAME_LAST_MODIFIED_DATE, ARGUMENT_NAME_LOCATION, ARGUMENT_NAME_LOG_MESSAGE, ARGUMENT_NAME_MIME_TYPE, ARGUMENT_NAME_NAMESPACE, ARGUMENT_NAME_NEW_PID, ARGUMENT_NAME_NUM_PIDS, ARGUMENT_NAME_OBJECT, ARGUMENT_NAME_OWNERID, ARGUMENT_NAME_PID, ARGUMENT_NAME_RELATIONSHIP, ARGUMENT_NAME_SERIALIZATION, ARGUMENT_NAME_START_DATE, ARGUMENT_NAME_STATE, ARGUMENT_NAME_VERSION_DATE, ARGUMENT_NAME_VERSIONABLE, ARGUMENT_TYPE_BINDING_MAP, ARGUMENT_TYPE_BOOLEAN, ARGUMENT_TYPE_DATE, ARGUMENT_TYPE_INTEGER, ARGUMENT_TYPE_NULL, ARGUMENT_TYPE_STREAM, ARGUMENT_TYPE_STRING, ARGUMENT_TYPE_STRINGARRAY, CONTEXT_MAPNAME_ACTION, CONTEXT_MAPNAME_ENVIRONMENT, CONTEXT_MAPNAME_RECOVERY, CONTEXT_MAPNAME_RESOURCE, CONTEXT_MAPNAME_SUBJECT, DEFAULT_AGE_LIMIT, DEFAULT_FILENAME_PREFIX, DEFAULT_SIZE_LIMIT, DOCUMENT_ENCODING, DOCUMENT_VERSION, FORMAT_JOURNAL_FILENAME_TIMESTAMP, METHOD_ADD_DATASTREAM, METHOD_ADD_DISSEMINATOR, METHOD_ADD_RELATIONSHIP, METHOD_GET_NEXT_PID, METHOD_INGEST, METHOD_MODIFY_DATASTREAM_BY_REFERENCE, METHOD_MODIFY_DATASTREAM_BY_VALUE, METHOD_MODIFY_DISSEMINATOR, METHOD_MODIFY_OBJECT, METHOD_PURGE_DATASTREAM, METHOD_PURGE_DISSEMINATOR, METHOD_PURGE_OBJECT, METHOD_PURGE_RELATIONSHIP, METHOD_PUT_TEMP_STREAM, METHOD_SET_DATASTREAM_STATE, METHOD_SET_DATASTREAM_VERSIONABLE, METHOD_SET_DISSEMINATOR_STATE, PARAMETER_IGNORE_HASH, PARAMETER_JOURNAL_FILE_AGE_LIMIT, PARAMETER_JOURNAL_FILE_SIZE_LIMIT, PARAMETER_JOURNAL_FILENAME_PREFIX, PARAMETER_JOURNAL_MODE, PARAMETER_JOURNAL_READER_CLASSNAME, PARAMETER_JOURNAL_RECOVERY_LOG_CLASSNAME, PARAMETER_JOURNAL_WRITER_CLASSNAME, PARAMETER_RECOVERY_LOG_FILENAME, PARAMETER_RECOVERY_LOG_LEVEL, PASSWORD_CIPHER_TYPE, QNAME_ATTR_BIND_KEY_NAME, QNAME_ATTR_BIND_LABEL, QNAME_ATTR_CLIENT_IP, QNAME_ATTR_DATASTREAM_ID, QNAME_ATTR_DS_BIND_MAP_ID, QNAME_ATTR_DS_BIND_MAP_LABEL, QNAME_ATTR_DS_BIND_MECHANISM_PID, QNAME_ATTR_LOGIN_ID, QNAME_ATTR_METHOD, QNAME_ATTR_NAME, QNAME_ATTR_PASSWORD_TYPE, QNAME_ATTR_REPOSITORY_HASH, QNAME_ATTR_SEQ_NO, QNAME_ATTR_STATE, QNAME_ATTR_TIMESTAMP, QNAME_ATTR_TYPE, QNAME_ATTR_USERID, QNAME_TAG_ARGUMENT, QNAME_TAG_ARRAYELEMENT, QNAME_TAG_CONTEXT, QNAME_TAG_DS_BINDING, QNAME_TAG_DS_BINDING_MAP, QNAME_TAG_JOURNAL, QNAME_TAG_JOURNAL_ENTRY, QNAME_TAG_MULTI_VALUE_MAP, QNAME_TAG_MULTI_VALUE_MAP_KEY, QNAME_TAG_MULTI_VALUE_MAP_VALUE, QNAME_TAG_NOOP, QNAME_TAG_NOW, QNAME_TAG_PASSWORD, SYSTEM_PROPERTY_PREFIX, TIMESTAMP_FORMAT, VALUE_FALSE, VALUE_JOURNAL_MODE_NORMAL, VALUE_JOURNAL_MODE_RECOVER, VALUE_RECOVERY_LOG_LEVEL_HIGH, VALUE_RECOVERY_LOG_LEVEL_LOW, VALUE_RECOVERY_LOG_LEVEL_MEDIUM, VALUE_TRUE

Constructor Summary

protected

JournalWriter(Map<String,String> parameters, String role, ServerInterface server) Concrete sub-classes must implement this constructor.

Method Summary

static JournalWriter	getInstance(Map<String,String> parameters, String role, ServerInterface server) Create an instance of the proper JournalWriter child class, as determined by the server parameters.
abstract void	prepareToWriteJournalEntry() Concrete sub-classes should insure that a message transport is ready, and call {@link #writeDocumentHeader(XMLEventWriter) if needed.
abstract void	shutdown()
protected void	writeDocumentHeader(XMLEventWriter writer) Subclasses should call this method to initialize a new Journal file.
protected void	writeDocumentHeader(XMLEventWriter writer, String repositoryHash, Date currentDate) Subclasses should call this method to initialize a new Journal file, if they already know the repository hash and the current date.
protected void	writeDocumentTrailer(XMLEventWriter writer) Subclasses should call this method to close a Journal file.
abstract void	writeJournalEntry(CreatorJournalEntry journalEntry) Concrete sub-classes should provide an XMLEventWriter, and call #writeJournalEntry(XMLEventWriter), after which, they should probably flush the XMLEventWriter.
protected void	writeJournalEntry(CreatorJournalEntry journalEntry, XMLEventWriter writer) Format a JournalEntry object and write a JournalEntry tag to the journal.

Methods inherited from class org.fcrepo.server.journal.xmlhelpers.AbstractXmlWriter

putAttribute, putAttributeIfNotNull, putCharacters, putEndDocument, putEndTag, putStartDocument, putStartTag

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

SYNCHRONIZER

public static final Object SYNCHRONIZER

A single object on which to synchronize all writing operations. The most obvious use is in CreatorJournalEntry to be sure that Management methods are single-threaded. A less obvious, but necessary use is to synchronize the timeout on JournalFiles, so a file is not closed in the middle of an operation.

role

protected final String role

parameters

protected final Map<String,String> parameters

server

protected final ServerInterface server

Constructor Detail

JournalWriter

protected JournalWriter(Map<String,String> parameters,
                        String role,
                        ServerInterface server)

Concrete sub-classes must implement this constructor.

Method Detail

getInstance

public static JournalWriter getInstance(Map<String,String> parameters,
                                        String role,
                                        ServerInterface server)
                                 throws JournalException

Create an instance of the proper JournalWriter child class, as determined by the server parameters.

Throws:

JournalException

shutdown

public abstract void shutdown()
                       throws JournalException

Throws:

JournalException

prepareToWriteJournalEntry

public abstract void prepareToWriteJournalEntry()
                                         throws JournalException

Concrete sub-classes should insure that a message transport is ready, and call #writeDocumentHeader(XMLEventWriter) if needed. This method is called separately from {@link #writeJournalEntry(CreatorJournalEntry)}, so we can obtain the repository hash before the Management method is invoked.

Throws:

JournalException

writeJournalEntry

public abstract void writeJournalEntry(CreatorJournalEntry journalEntry)
                                throws JournalException

Concrete sub-classes should provide an XMLEventWriter, and call #writeJournalEntry(XMLEventWriter), after which, they should probably flush the XMLEventWriter. This method is called after the Management method is invoked, since the Management method may modify the context object in the journal entry.

Throws:

JournalException

writeDocumentHeader

protected void writeDocumentHeader(XMLEventWriter writer)
                            throws JournalException

Subclasses should call this method to initialize a new Journal file.

Throws:

JournalException

writeDocumentHeader

protected void writeDocumentHeader(XMLEventWriter writer,
                                   String repositoryHash,
                                   Date currentDate)
                            throws JournalException

Subclasses should call this method to initialize a new Journal file, if they already know the repository hash and the current date.

Throws:

JournalException

writeDocumentTrailer

protected void writeDocumentTrailer(XMLEventWriter writer)
                             throws JournalException

Subclasses should call this method to close a Journal file.

Throws:

JournalException

writeJournalEntry

protected void writeJournalEntry(CreatorJournalEntry journalEntry,
                                 XMLEventWriter writer)
                          throws JournalException

Format a JournalEntry object and write a JournalEntry tag to the journal.

Throws:

JournalException