Package com.ibm.di.server

Class ReconnectRuleEngine

  • public class ReconnectRuleEngine
extends java.lang.Object

    This class decides what to do when a connector raises an error. Possible actions are to attempt a reconnect or leave the error unhandled and let further mechanisms process it.

    The class makes decisions based on configured rules. Each rule describes what should be done when an error occurs. Each rule applies to certain connectors and certain errors. In a rule the connectors are described by their base Java class and their name in the current configuration. (there are match-all options for both the class and the name of the connector). A rule describes applicable errors by their base Java class and a regular expression that matches their messages (the regular expression is optional).

    The reconnect engine holds two collections of rules: in-built rules and user-defined rules.

    The in-built rules are defined in an '.inf' file in the jar file of the corresponding connector. They are specific to that connector class. In order to preserver the reconnect behaviour, which existed before the introduction of ReconnectRuleEngine, when the engine is created, it implicitly adds to the in-built rules rules, which prescribe to attempt reconnect on all IOException-s and all CommunicationException-s.

    The user defined rules reside in an external text file.

    • Field Summary

      Fields 
      Modifier and Type Field Description
      static int ERROR
      the situation is a fatal error which no reconnect could fix
      static java.lang.String ERROR_STRING
      error action - no reconnect will be attempted
      static int INVALID_RECONNECT_ACTION
      invalid reconnect action
      static int RECONNECT
      reconnect should be attempted to fix the error situation
      static char RECONNECT_RULE_PARTS_DELIMETER
      the delimiter of the parts of a rule in the config file
      static java.lang.String RECONNECT_STRING
      reconnect action - if an error occurs reconnect will be attempted

    • Constructor Summary

      Constructors 
      Constructor Description
      ReconnectRuleEngine​(Log log)
      Constructor, which loads the in-built rules and the user-defined rules.

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      int getReconnectChoice​(ConnectorInterface connector, java.lang.Throwable error)
      This method prescribes a response action for a given error situation.
      void loadRules​(java.lang.String userDefinedRulesFilePath, MetamergeConfig sysConfig)
      Loads the in-built and the user-defined rules.

      • Methods inherited from class java.lang.Object

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

    • Field Detail

      • INVALID_RECONNECT_ACTION

        public static final int INVALID_RECONNECT_ACTION
        invalid reconnect action
        See Also:
        Constant Field Values

      • ERROR

        public static final int ERROR
        the situation is a fatal error which no reconnect could fix
        See Also:
        Constant Field Values

      • RECONNECT

        public static final int RECONNECT
        reconnect should be attempted to fix the error situation
        See Also:
        Constant Field Values

      • RECONNECT_RULE_PARTS_DELIMETER

        public static final char RECONNECT_RULE_PARTS_DELIMETER
        the delimiter of the parts of a rule in the config file
        See Also:
        Constant Field Values

      • ERROR_STRING

        public static final java.lang.String ERROR_STRING
        error action - no reconnect will be attempted
        See Also:
        Constant Field Values

      • RECONNECT_STRING

        public static final java.lang.String RECONNECT_STRING
        reconnect action - if an error occurs reconnect will be attempted
        See Also:
        Constant Field Values

    • Constructor Detail

      • ReconnectRuleEngine

        public ReconnectRuleEngine​(Log log)
        Constructor, which loads the in-built rules and the user-defined rules.
        Parameters:
        log - a log object to be used during the lifetime of the engine

    • Method Detail

      • loadRules

        public void loadRules​(java.lang.String userDefinedRulesFilePath,
                      MetamergeConfig sysConfig)
               throws java.lang.Exception
        Loads the in-built and the user-defined rules.
        Parameters:
        userDefinedRulesFilePath - the file with user-defined rules
        sysConfig - system configuration object, which has the in-built rules of all connectors
        Throws:
        java.lang.Exception - problem while parsing the configured rules ClassNotFoundException problem while loading an exception/connector class, specified in a rule

      • getReconnectChoice

        public int getReconnectChoice​(ConnectorInterface connector,
                              java.lang.Throwable error)

        This method prescribes a response action for a given error situation.

        First searches the user-defined rules and if no matching rule is found, the method searches the Connector own rules. If a rule cannot be found in either collection, the default action (ERROR) is prescribed.

        When a collection (in-built or user-defined) is searched for a matching rule, first is sought a match for the error itself. If no match is found for the error and the error has a specified cause (getCause() returns non-null) then a match for the cause is searched. Only when both searched fail, another collection of rules is considered.

        Parameters:
        connector - the connector, which raised the error
        error - the error object
        Returns:
        the prescribed action - it is one of the following: ERROR or RECONNECT