Package com.lightstreamer.interfaces.metadata

Class MetadataProviderAdapter

java.lang.Object
com.lightstreamer.interfaces.metadata.MetadataProviderAdapter
All Implemented Interfaces:
MetadataProvider
Direct Known Subclasses:
LiteralBasedProvider
public abstract class MetadataProviderAdapter extends Object implements MetadataProvider
Provides a default implementation of all the MetadataProvider interface methods. Overriding this class may facilitate the coding of simple Metadata Adapters.

  • Constructor Summary

    Constructors
    Constructor
    Description
    MetadataProviderAdapter()
     

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    customizeUpdate(String user, String item, CustomizableItemEvent event)
    Called by Lightstreamer Kernel in order to customize events pertaining to an ItemEventBuffer, if such customization has been requested through the enableUpdateCustomization method.
    boolean
    enableUpdateCustomization(String user, String item)
    Called by Lightstreamer Kernel to know whether the Metadata Adapter must or must not be given a chance to modify the values carried by the updates for a supplied Item in a push Session owned by a supplied User.
    int
    getAllowedBufferSize(String user, String item)
    Called by Lightstreamer Kernel to ask for the maximum allowed size of the buffer internally used to enqueue subsequent ItemUpdates for the same Item.
    double
    getAllowedMaxBandwidth(String user)
    Called by Lightstreamer Kernel to ask for the bandwidth amount to be allowed to a User for a push Session.
    double
    getAllowedMaxItemFrequency(String user, String item)
    Called by Lightstreamer Kernel to ask for the ItemUpdate frequency to be allowed to a User for a specific Item.
    int
    getDistinctSnapshotLength(String item)
    Called by Lightstreamer Kernel to ask for the maximum allowed length for a Snapshot of an Item that has been requested with publishing Mode DISTINCT.
    double
    getMinSourceFrequency(String item)
    Called by Lightstreamer Kernel to ask for the minimum ItemEvent frequency that ensures that all subscribers of an Item can be fed with an adequate amount of information.
    void
    init(Map params, File configDir)
    No-op initialization.
    boolean
    isModeAllowed(String user, String item, Mode mode)
    Called by Lightstreamer Kernel to ask for the allowance of a publishing Mode for an Item.
    boolean
    isSelected(String user, String item, String selector, ItemEvent event)
    Called by Lightstreamer Kernel in order to filter events pertaining to an ItemEventBuffer, if the related Item was requested within a Table (i.e.: Subscription) with an associated Selector.
    boolean
    isSelectorAllowed(String user, String item, String selector)
    Called by Lightstreamer Kernel to ask for the allowance of a Selector for an Item.
    boolean
    modeMayBeAllowed(String item, Mode mode)
    Called by Lightstreamer Kernel to ask for the allowance of a publishing Mode for an Item (for at least one User).
    void
    notifyMpnDeviceAccess(String user, String sessionID, MpnDeviceInfo device)
    Called by Lightstreamer Kernel to check that a User is enabled to access the specified MPN device.
    void
    notifyMpnDeviceTokenChange(String user, String sessionID, MpnDeviceInfo device, String newDeviceToken)
    Called by Lightstreamer Kernel to check that a User is enabled to change the token of a MPN device.
    void
    notifyMpnSubscriptionActivation(String user, String sessionID, TableInfo table, MpnSubscriptionInfo mpnSubscription)
    Called by Lightstreamer Kernel to check that a User is enabled to activate a Push Notification subscription.
    void
    notifyNewSession(String user, String sessionID)
    2-arguments version of the User authentication method.
    void
    notifyNewSession(String user, String sessionID, Map clientContext)
    Called by Lightstreamer Kernel to check that a User is enabled to open a new push Session.
    void
    notifyNewTables(String user, String sessionID, TableInfo[] tables)
    Called by Lightstreamer Kernel to check that a User is enabled to add some Tables (i.e.: Subscriptions) to a push Session.
    void
    notifySessionClose(String sessionID)
    Called by Lightstreamer Kernel to notify the Metadata Adapter that a push Session has been closed.
    void
    notifyTablesClose(String sessionID, TableInfo[] tables)
    Called by Lightstreamer Kernel to notify the Metadata Adapter that some Tables (i.e.: Subscriptions) have been removed from a push Session.
    void
    notifyUser(String user, String password)
    2-arguments version of the User authentication method.
    void
    notifyUser(String user, String password, Map httpHeaders)
    Called by Lightstreamer Kernel as a preliminary check that a user is enabled to make Requests to the related Data Providers.
    void
    notifyUser(String user, String password, Map httpHeaders, String clientPrincipal)
    Extended version of the User authentication method, invoked by the Server in case it has been instructed (through the <use_client_auth> configuration flag) to acquire the client principal from the client TLS/SSL certificate, if available.
    void
    notifyUserMessage(String user, String sessionID, String message)
    Called by Lightstreamer Kernel to forward a message received by a User.
    boolean
    wantsTablesNotification(String user)
    Called by Lightstreamer Kernel to know whether the Metadata Adapter must or must not be notified any time a Table (i.e.: Subscription) is added or removed from a push Session owned by a supplied User.

    Methods inherited from class java.lang.Object

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

    Methods inherited from interface com.lightstreamer.interfaces.metadata.MetadataProvider

    getItems, getSchema, getSessionTimeToLive, setListener

  • Constructor Details

    • MetadataProviderAdapter

      public MetadataProviderAdapter()

  • Method Details

    • init

      public void init(@Nonnull Map params, @Nonnull File configDir) throws MetadataProviderException
      No-op initialization.
      Specified by:
      init in interface MetadataProvider
      Parameters:
      params - not used.
      configDir - not used.
      Throws:
      MetadataProviderException - never thrown.

    • notifyUser

      public void notifyUser(@Nullable String user, @Nullable String password, @Nonnull Map httpHeaders) throws AccessException, CreditsException
      Called by Lightstreamer Kernel as a preliminary check that a user is enabled to make Requests to the related Data Providers.
      In this default implementation, a simpler 2-arguments version of the method is invoked, where the httpHeaders argument is discarded. This also ensures backward compatibility with old adapter classes derived from this one.
      Note that, for authentication purposes, only the user and password arguments should be consulted.
      Specified by:
      notifyUser in interface MetadataProvider
      Parameters:
      user - A User name.
      password - A password optionally required to validate the User.
      httpHeaders - A Map-type value object that contains a name-value pair for each header found in the HTTP request that originated the call. Not used.
      Throws:
      AccessException - never thrown
      CreditsException - never thrown
      See Also:

    • notifyUser

      public void notifyUser(@Nullable String user, @Nullable String password) throws AccessException, CreditsException
      2-arguments version of the User authentication method. In case the 3-arguments version of the method is not overridden, this version of the method is invoked.
      In this default implementation, the Metadata Adapter poses no restriction.
      Parameters:
      user - not used.
      password - not used.
      Throws:
      AccessException - never thrown.
      CreditsException - never thrown.

    • notifyUser

      public void notifyUser(@Nullable String user, @Nullable String password, @Nonnull Map httpHeaders, @Nonnull String clientPrincipal) throws AccessException, CreditsException
      Extended version of the User authentication method, invoked by the Server in case it has been instructed (through the <use_client_auth> configuration flag) to acquire the client principal from the client TLS/SSL certificate, if available.
      In this default implementation, the base 3-arguments version of the method is invoked, where the clientPrincipal argument is discarded. This also ensures backward compatibility with old adapter classes derived from this one.
      Edition Note:
      https is an optional feature, available depending on Edition and License Type. To know what features are enabled by your license, please see the License tab of the Monitoring Dashboard (by default, available at /dashboard).
      Specified by:
      notifyUser in interface MetadataProvider
      Parameters:
      user - A User name.
      password - A password optionally required to validate the User.
      httpHeaders - A Map-type value object that contains a name-value pair for each header found in the HTTP request that originated the call.
      clientPrincipal - the identification name reported in the client TLS/SSL certificate supplied on the socket connection used to issue the request that originated the call; it can be null if client has not authenticated itself or the authentication has failed. Not used.
      Throws:
      AccessException - never thrown
      CreditsException - never thrown

    • getAllowedMaxBandwidth

      public double getAllowedMaxBandwidth(@Nullable String user)
      Called by Lightstreamer Kernel to ask for the bandwidth amount to be allowed to a User for a push Session. In this default implementation, the Metadata Adapter poses no restriction.
      Specified by:
      getAllowedMaxBandwidth in interface MetadataProvider
      Parameters:
      user - not used.
      Returns:
      always zero, to mean no bandwidth limit.

    • getAllowedMaxItemFrequency

      public double getAllowedMaxItemFrequency(@Nullable String user, @Nonnull String item)
      Called by Lightstreamer Kernel to ask for the ItemUpdate frequency to be allowed to a User for a specific Item. In this default implementation, the Metadata Adapter poses no restriction; this also enables unfiltered dispatching for Items subscribed in MERGE or DISTINCT mode.
      Specified by:
      getAllowedMaxItemFrequency in interface MetadataProvider
      Parameters:
      user - not used.
      item - not used.
      Returns:
      always zero, to mean no frequency limit.

    • getAllowedBufferSize

      public int getAllowedBufferSize(@Nullable String user, @Nonnull String item)
      Called by Lightstreamer Kernel to ask for the maximum allowed size of the buffer internally used to enqueue subsequent ItemUpdates for the same Item. In this default implementation, the Metadata Adapter poses no restriction.
      Specified by:
      getAllowedBufferSize in interface MetadataProvider
      Parameters:
      user - not used.
      item - not used.
      Returns:
      always zero, to mean no size limit.

    • isModeAllowed

      public boolean isModeAllowed(@Nullable String user, @Nonnull String item, @Nonnull Mode mode)
      Called by Lightstreamer Kernel to ask for the allowance of a publishing Mode for an Item. A publishing Mode can or cannot be allowed depending on the User. In this default implementation, the Metadata Adapter poses no restriction. As a consequence, conflicting Modes may be both allowed for the same Item, so the Clients should ensure that the same Item cannot be requested in two conflicting Modes.
      Specified by:
      isModeAllowed in interface MetadataProvider
      Parameters:
      user - not used.
      item - not used.
      mode - not used.
      Returns:
      always true.

    • modeMayBeAllowed

      public boolean modeMayBeAllowed(@Nonnull String item, @Nonnull Mode mode)
      Called by Lightstreamer Kernel to ask for the allowance of a publishing Mode for an Item (for at least one User). In this default implementation, the Metadata Adapter poses no restriction. As a consequence, conflicting Modes may be both allowed for the same Item, so the Clients should ensure that the same Item cannot be requested in two conflicting Modes.
      This is just to simplify the development phase; the final implementation of the method MUST be different, to ensure that conflicting modes (i.e. MERGE, DISTINCT and COMMAND) are not both allowed for the same Item.
      Specified by:
      modeMayBeAllowed in interface MetadataProvider
      Parameters:
      item - not used.
      mode - not used.
      Returns:
      always true.

    • isSelectorAllowed

      public boolean isSelectorAllowed(@Nullable String user, @Nonnull String item, @Nonnull String selector)
      Called by Lightstreamer Kernel to ask for the allowance of a Selector for an Item. Typically, a Selector is intended for one Item or for a specific set of Items with some characteristics. In this default implementation, selectors are always allowed.
      Specified by:
      isSelectorAllowed in interface MetadataProvider
      Parameters:
      user - not used.
      item - not used.
      selector - not used.
      Returns:
      always true, to mean that the Selector is allowed.

    • isSelected

      public boolean isSelected(@Nullable String user, @Nonnull String item, @Nonnull String selector, @Nonnull ItemEvent event)
      Called by Lightstreamer Kernel in order to filter events pertaining to an ItemEventBuffer, if the related Item was requested within a Table (i.e.: Subscription) with an associated Selector. If the return value is true, the event is dispatched to the ItemEventBuffer; otherwise, it is filtered out. In this default implementation, no event is filtered out, regardless of the Selector.
      Specified by:
      isSelected in interface MetadataProvider
      Parameters:
      user - not used.
      item - not used.
      selector - not used.
      event - not used.
      Returns:
      always true, to mean that the event is to be processed by the ItemEventBuffer.

    • enableUpdateCustomization

      public boolean enableUpdateCustomization(@Nullable String user, @Nonnull String item)
      Called by Lightstreamer Kernel to know whether the Metadata Adapter must or must not be given a chance to modify the values carried by the updates for a supplied Item in a push Session owned by a supplied User. In this default implementation, updates are never to be modified.
      Specified by:
      enableUpdateCustomization in interface MetadataProvider
      Parameters:
      user - not used.
      item - not used.
      Returns:
      always false, to mean that the Kernel should never ask for update values modifications.

    • customizeUpdate

      public void customizeUpdate(@Nullable String user, @Nonnull String item, @Nonnull CustomizableItemEvent event)
      Called by Lightstreamer Kernel in order to customize events pertaining to an ItemEventBuffer, if such customization has been requested through the enableUpdateCustomization method. In this default implementation, updates are never modified.
      Specified by:
      customizeUpdate in interface MetadataProvider
      Parameters:
      user - not used.
      item - not used.
      event - not used.

    • getMinSourceFrequency

      public double getMinSourceFrequency(@Nonnull String item)
      Called by Lightstreamer Kernel to ask for the minimum ItemEvent frequency that ensures that all subscribers of an Item can be fed with an adequate amount of information. In practice, in case of an incoming ItemEvent frequency from the Data Adapter that is greater than the specified value, Lightstreamer Kernel may prefilter the events flow, by resampling it down to the specified frequency, before feeding the ItemEventBuffers. Such prefiltering applies only for Items requested with publishing Mode MERGE or DISTINCT. In this default implementation, the Metadata Adapter can't set any minimum frequency; this also enables unfiltered dispatching for Items subscribed in MERGE or DISTINCT mode.
      Specified by:
      getMinSourceFrequency in interface MetadataProvider
      Parameters:
      item - not used.
      Returns:
      always zero, to mean that incoming ItemEvents must not be prefiltered.

    • getDistinctSnapshotLength

      public int getDistinctSnapshotLength(@Nonnull String item)
      Called by Lightstreamer Kernel to ask for the maximum allowed length for a Snapshot of an Item that has been requested with publishing Mode DISTINCT. In this default implementation, 0 events are specified, so snapshot will not be managed.
      Specified by:
      getDistinctSnapshotLength in interface MetadataProvider
      Parameters:
      item - An Item Name.
      Returns:
      a value of 0, to mean that no events will be kept in order to satisfy snapshot requests.

    • notifyUserMessage

      public void notifyUserMessage(@Nullable String user, @Nonnull String sessionID, @Nonnull String message) throws CreditsException, NotificationException
      Called by Lightstreamer Kernel to forward a message received by a User. In this default implementation, the Metadata Adapter does never accept the message.
      Specified by:
      notifyUserMessage in interface MetadataProvider
      Parameters:
      user - not used.
      sessionID - not used.
      message - not used.
      Throws:
      CreditsException - always thrown.
      NotificationException - never thrown.

    • notifyNewSession

      public void notifyNewSession(@Nullable String user, @Nonnull String sessionID, @Nonnull Map clientContext) throws CreditsException, NotificationException
      Called by Lightstreamer Kernel to check that a User is enabled to open a new push Session.
      In this default implementation, a simpler 2-arguments version of the method is invoked, where the clientContext argument is discarded. This also ensures backward compatibility with old adapter classes derived from this one.
      Specified by:
      notifyNewSession in interface MetadataProvider
      Parameters:
      user - A User name.
      sessionID - The ID of a new Session.
      clientContext - not used.
      Throws:
      CreditsException - never thrown
      NotificationException - never thrown

    • notifyNewSession

      public void notifyNewSession(@Nullable String user, @Nonnull String sessionID) throws CreditsException, NotificationException
      2-arguments version of the User authentication method. In case the 3-arguments version of the method is not overridden, this version of the method is invoked.
      In this default implementation, the Metadata Adapter poses no restriction.
      Parameters:
      user - not used.
      sessionID - not used.
      Throws:
      CreditsException - never thrown.
      NotificationException - never thrown.

    • notifySessionClose

      public void notifySessionClose(@Nonnull String sessionID) throws NotificationException
      Called by Lightstreamer Kernel to notify the Metadata Adapter that a push Session has been closed. In this default implementation, the Metadata Adapter does nothing, because it doesn't need to remember the open Sessions.
      Specified by:
      notifySessionClose in interface MetadataProvider
      Parameters:
      sessionID - not used.
      Throws:
      NotificationException - never thrown.

    • wantsTablesNotification

      public boolean wantsTablesNotification(@Nullable String user)
      Called by Lightstreamer Kernel to know whether the Metadata Adapter must or must not be notified any time a Table (i.e.: Subscription) is added or removed from a push Session owned by a supplied User. In this default implementation, the Metadata Adapter doesn't require such notifications.
      Specified by:
      wantsTablesNotification in interface MetadataProvider
      Parameters:
      user - not used.
      Returns:
      always false, to prevent being notified with notifyNewTables and notifyTablesClose.

    • notifyNewTables

      public void notifyNewTables(@Nullable String user, @Nonnull String sessionID, @Nonnull TableInfo[] tables) throws CreditsException, NotificationException
      Called by Lightstreamer Kernel to check that a User is enabled to add some Tables (i.e.: Subscriptions) to a push Session. If the check succeeds, this also notifies the Metadata Adapter that the Tables are being added to the Session. In this default implementation, the Metadata Adapter poses no restriction. Unless the wantsTablesNotification(java.lang.String) method is overridden, this method will never be called by Lightstreamer Kernel.
      Specified by:
      notifyNewTables in interface MetadataProvider
      Parameters:
      user - not used.
      sessionID - not used.
      tables - not used.
      Throws:
      CreditsException - never thrown.
      NotificationException - never thrown.

    • notifyTablesClose

      public void notifyTablesClose(@Nonnull String sessionID, @Nonnull TableInfo[] tables) throws NotificationException
      Called by Lightstreamer Kernel to notify the Metadata Adapter that some Tables (i.e.: Subscriptions) have been removed from a push Session. In this default implementation, the Metadata Adapter does nothing, because it doesn't need to remember the Tables used. Unless the wantsTablesNotification(java.lang.String) method is overridden, this method will never be called by Lightstreamer Kernel.
      Specified by:
      notifyTablesClose in interface MetadataProvider
      Parameters:
      sessionID - not used.
      tables - not used.
      Throws:
      NotificationException - never thrown.

    • notifyMpnDeviceAccess

      public void notifyMpnDeviceAccess(@Nullable String user, @Nonnull String sessionID, @Nonnull MpnDeviceInfo device) throws CreditsException, NotificationException
      Called by Lightstreamer Kernel to check that a User is enabled to access the specified MPN device. In this default implementation, the Metadata Adapter poses no restriction.
      Edition Note:
      Push Notifications is an optional feature, available depending on Edition and License Type. To know what features are enabled by your license, please see the License tab of the Monitoring Dashboard (by default, available at /dashboard).
      Specified by:
      notifyMpnDeviceAccess in interface MetadataProvider
      Parameters:
      user - not used.
      sessionID - not used.
      device - not used.
      Throws:
      CreditsException - never thrown.
      NotificationException - never thrown.

    • notifyMpnSubscriptionActivation

      public void notifyMpnSubscriptionActivation(@Nullable String user, @Nonnull String sessionID, @Nonnull TableInfo table, @Nonnull MpnSubscriptionInfo mpnSubscription) throws CreditsException, NotificationException
      Called by Lightstreamer Kernel to check that a User is enabled to activate a Push Notification subscription. In this default implementation, the Metadata Adapter poses no restriction.
      Edition Note:
      Push Notifications is an optional feature, available depending on Edition and License Type.
      Specified by:
      notifyMpnSubscriptionActivation in interface MetadataProvider
      Parameters:
      user - not used.
      sessionID - not used.
      table - not used.
      mpnSubscription - not used.
      Throws:
      CreditsException - never thrown.
      NotificationException - never thrown.

    • notifyMpnDeviceTokenChange

      public void notifyMpnDeviceTokenChange(@Nullable String user, @Nonnull String sessionID, @Nonnull MpnDeviceInfo device, @Nonnull String newDeviceToken) throws CreditsException, NotificationException
      Called by Lightstreamer Kernel to check that a User is enabled to change the token of a MPN device. In this default implementation, the Metadata Adapter poses no restriction.
      Edition Note:
      Push Notifications is an optional feature, available depending on Edition and License Type. To know what features are enabled by your license, please see the License tab of the Monitoring Dashboard (by default, available at /dashboard).
      Specified by:
      notifyMpnDeviceTokenChange in interface MetadataProvider
      Parameters:
      user - not used.
      sessionID - not used.
      device - not used.
      newDeviceToken - not used.
      Throws:
      CreditsException - never thrown.
      NotificationException - never thrown.