com.google.enterprise.connector.spi

Interface DatabaseResourceBundle

All Known Implementing Classes:

DatabasePropertyResourceBundle

public interface DatabaseResourceBundle

Supplies SQL language syntax variations for the various database implementations. This mirrors java.util.ResourceBundle in form and function, but is designed to supply SQL language translations rather than spoken language translations.

Like java.util.PropertyResourceBundle, DatabaseResourceBundle resources are specified in Properties files. Unlike PropertyResourceBundle, DatabaseResourceBundle uses the EProperties enhanced Properties package, which extends the standard java.util.Properties and syntax to include things like: variable substitution, nesting, inclusion and lists. For instance:

• Variable substitution syntax that mirrors the syntax used in shell scripts, ant, etc.:

   table.name = connector_instances
   getvalue.query = "SELECT ${column.connector.name} FROM ${table.name} ..."
   

  Variables may be defined in the DatabaseResourceBundle in which they are used, or any of the ancestor DatabaseResourceBundles (see below). Variable substitution is done at the time of the call to getString(String) or getStringArray(String), so the returned string(s) have all known substitutions resolved.
• Lists that may be fetched as an array of Strings - great for potentially multi-statement DDL. For instance, this table creation DDL resource definition consists of three distinct SQL statements:

   create.table.ddl = ( "CREATE TABLE ...", "CREATE TRIGGER ...", "CREATE INDEX ..." )
   

  which can be retrieved using getStringArray(String):

   String[] ddlStatements = bundle.getStringArray("create.table.ddl");
   

These features allow the connector developer to write very powerful resource property files.

Connectors must locate the DatabaseResourceBundle property files in their config package. The properties files have a base name derived from the ConnectorType name (with any instances of '.' replaced with '_') concatenated with "_sql". Vendor-specific SQL syntax variations are formed by adding the product name, major and minor versions to the base name. So resource property file names would look like:

 <ConnectorTypeName>_sql[_productName][_majorVersion][_minorVersion].properties
 

For instance, suppose the ConnectorType name as defined in connectorType.xml is "File.List", and the configured JDBC DataSource is MySQL v5.1. The Connector Manager will attempt to load DatabaseResourceBundles from the following resources:

1. config.File_List_sql_mysql_5_1.properties
2. config.File_List_sql_mysql_5.properties
3. config.File_List_sql_mysql.properties
4. config.File_List_sql.properties

Resources are searched in that order, from most specific to least specific. Variable substitution are also resolved from most specific to least specific, so File_List_sql_mysql.properties may refer to a property defined in File_List_sql.properties, but not one defined in File_List_sql_mysql_5_1.properties.

Since:

2.8

Method Summary

Modifier and Type	Method and Description
java.lang.String	getString(java.lang.String key) Gets a resource that is specific to the active database implementation.
java.lang.String[]	getStringArray(java.lang.String key) The same comments apply as {getString(String), only this API corresponds to ResourceBundle.getStringArray(String).

Method Detail

getString

java.lang.String getString(java.lang.String key)

Gets a resource that is specific to the active database implementation. This API is modeled on ResourceBundle.getString(String) and is intended to be used in a similar way. That is, it may return a String (typically, SQL) into which parameter substitution may be done using Format.format(Object), JDBC PreparedStatement and similar techniques.

The implementation will assure that the correct resource is returned for this connector type and for the active database implementation.

If there is no resource defined for this key, null is returned (unlike ResourceBundle.getString(String), which throws an exception).

Parameters:

key - as ResourceBundle.getString(String)

Returns:

as ResourceBundle.getString(String)

getStringArray

java.lang.String[] getStringArray(java.lang.String key)

The same comments apply as {getString(String), only this API corresponds to ResourceBundle.getStringArray(String).

If there is no resource defined for this key, an array of length zero is returned (unlike ResourceBundle.getString(String), which throws an exception).

Parameters:

key - as ResourceBundle.getStringArray(String)

Returns:

as ResourceBundle.getStringArray(String)