Package com.lightstreamer.kafka.adapters.pub

Class KafkaConnectorMetadataAdapter

java.lang.Object

com.lightstreamer.interfaces.metadata.MetadataProviderAdapter

com.lightstreamer.kafka.adapters.pub.KafkaConnectorMetadataAdapter

All Implemented Interfaces:

MetadataProvider

public class KafkaConnectorMetadataAdapter
extends MetadataProviderAdapter

Implementation of a Lightstreamer Metadata Adapter for Lightstreamer Kafka Connector.

For the sake of simplicity, this documentation shows only the hook methods.

Constructor Summary

Constructors

Constructor	Description
KafkaConnectorMetadataAdapter()

Method Summary

Modifier and Type	Method	Description
String[]	getSchema(String user, String sessionID, String group, String dataAdapter, String schema)	Resolves a Field List specification supplied in a Request.
void	onSubscription(String user, String sessionID, TableInfo[] tables)	Hook method invoked by Lightstreamer Kernel to notify that a user has submitted a Subscription.
void	onUnsubscription(String sessionID, TableInfo[] tables)	Hook method invoked by Lightstreamer Kernel to notify that a Subscription has been removed from a push session.
protected void	postInit(Map params, File configDir)	Hook method invoked by Lightstreamer Kernel after the initialization phase of the Kafka Connector Metadata Adapter has been completed.
String[]	remapItems(String user, String sessionID, String itemList, String dataAdapter)	Remaps a list of items for a specific user session and data adapter.

Methods inherited from class com.lightstreamer.interfaces.metadata.MetadataProviderAdapter

customizeUpdate, customizeUpdate, enableUpdateCustomization, enableUpdateCustomization, getAllowedBufferSize, getAllowedBufferSize, getAllowedMaxBandwidth, getAllowedMaxItemFrequency, getAllowedMaxItemFrequency, getDistinctSnapshotLength, getDistinctSnapshotLength, getMinSourceFrequency, getMinSourceFrequency, isModeAllowed, isModeAllowed, isSelected, isSelected, isSelectorAllowed, isSelectorAllowed, modeMayBeAllowed, modeMayBeAllowed, notifyMpnDeviceAccess, notifyMpnDeviceTokenChange, notifyMpnSubscriptionActivation, notifyNewSession, notifyNewSession, notifySessionClose, notifyUser, notifyUser, notifyUserMessage

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

getSessionTimeToLive, setListener

Constructor Details

KafkaConnectorMetadataAdapter

public KafkaConnectorMetadataAdapter()

Method Details

postInit

protected void postInit(Map params,
 File configDir)
                 throws MetadataProviderException

Hook method invoked by Lightstreamer Kernel after the initialization phase of the Kafka Connector Metadata Adapter has been completed.

Parameters:

params - a Map-type value object that contains name-value pairs corresponding to the param elements supplied in the KafkaConnector configuration file under the <metadata_provider> element

configDir - the path of the directory on the local disk where the KafkaConnector configuration file resides

Throws:

MetadataProviderException - if an error occurs that prevents the correct behavior of the Metadata Adapter. This causes the Server not to complete the startup and to exit.

See Also:

• MetadataProvider.init(java.util.Map, java.io.File)

getSchema

public String[] getSchema(String user,
 String sessionID,
 String group,
 String dataAdapter,
 String schema)
                   throws ItemsException,
SchemaException

Resolves a Field List specification supplied in a Request. The names of the Fields in the List are returned.

Field List specifications are expected to be formed by simply concatenating the names of the contained Fields, in a space separated way.

Parameters:

user - a User name

sessionID - a Session ID

group - the name of the Item Group (or specification of the Item List) whose Items the Schema is to be applied to

dataAdapter - the name of the Data Adapter to which the subscription is targeted

schema - a Field Schema name (or Field List specification)

Returns:

an array with the names of the Fields in the Schema

Throws:

ItemsException - if the supplied Item Group name (or Item List specification) is not recognized

SchemaException - if the supplied Field Schema name (or Field List specification) is not recognized

remapItems

public String[] remapItems(String user,
 String sessionID,
 String itemList,
 String dataAdapter)
                    throws ItemsException

Remaps a list of items for a specific user session and data adapter.

This method processes a whitespace-separated string of items and converts it into an array of individual item names. If the input is null or empty after trimming, an empty array is returned.

Override this method to provide custom item resolution logic

Parameters:

user - a User name

sessionID - a Session ID

itemList - an Item List specification (whitespace-separated item names)

dataAdapter - the name of the Data Adapter to which the Item List is targeted

Returns:

an array of strings containing the individual item names, or an empty array if the input is null or empty

Throws:

ItemsException - if there are issues with the items during the remapping process

onSubscription

public void onSubscription(@Nullable
 String user,
 @Nonnull
 String sessionID,
 @Nonnull
 TableInfo[] tables)
                    throws CreditsException,
NotificationException

Hook method invoked by Lightstreamer Kernel to notify that a user has submitted a Subscription.

In this default implementation, the KafkaConnector Metadata Adapter does nothing.

Parameters:

user - a user name

sessionID - the ID of a session owned by the user

tables - an array of TableInfo instances, each of them containing the details of a Subscription to be added to the session

Throws:

CreditsException - if the user is not allowed to submit the Subscription

NotificationException - if something is wrong in the parameters, such as the sessionID of a session that is not currently open or inconsistent information about the Subscription

See Also:

• MetadataProvider.notifyNewTables(java.lang.String, java.lang.String, com.lightstreamer.interfaces.metadata.TableInfo)

onUnsubscription

public void onUnsubscription(@Nonnull
 String sessionID,
 @Nonnull
 TableInfo[] tables)
                      throws NotificationException

Hook method invoked by Lightstreamer Kernel to notify that a Subscription has been removed from a push session.

In this default implementation, the KafkaConnector Metadata Adapter does nothing.

Parameters:

sessionID - the ID of a session owned by the user

tables - an array of TableInfo instances, each of them containing the details of a Subscription that has been removed from the session

Throws:

NotificationException - if something is wrong in the parameters, such as the sessionID of a session that is not currently open or inconsistent information about the Subscription

See Also:

• MetadataProvider.notifyTablesClose(java.lang.String, com.lightstreamer.interfaces.metadata.TableInfo)