com.tibco.ftl

Interface Publisher

public interface Publisher

Publisher objects send messages.

A publisher object realizes the message-sending functionality of an endpoint within a program.

A publisher object encapsulates all the information that a program needs to send a stream of messages. Publisher objects use the transport and format resources associated with an endpoint (as defined in the realm).

Programs can use a publisher to send messages one-to-many, or one-to-one.

To create a publisher object, call Realm.createPublisher.

Customers do not implement this interface.

Field Summary

Fields

Modifier and Type	Field and Description
static java.lang.String	PROPERTY_BOOL_RELEASE_MSGS_TO_SEND Ownership of outbound messages; boolean.
static java.lang.String	PROPERTY_DOUBLE_PERSISTENCE_CLOSE_LINGER Linger duration for persistent publisher close operation; double.
static java.lang.String	PROPERTY_DOUBLE_PERSISTENCE_RETRY_DURATION Retry duration for persistent publisher operations; double.
static java.lang.String	PROPERTY_INT_MAX_BATCH_COUNT Maximum batch count for non-inline publishers; integer.
static java.lang.String	PROPERTY_INT_SEND_POLICY Publisher send policy; string.
static java.lang.String	PROPERTY_STRING_LABEL Property name for a publisher label; string.
static java.lang.String	PROPERTY_STRING_REPLY_ENDPOINT Property name for a publisher reply endpoint; string.
static int	SEND_INLINE Publish with low latency; integer.
static int	SEND_NON_INLINE Publish with high throughput; integer.

Method Summary

Modifier and Type	Method and Description
void	close() Close a publisher.
void	flush() When the publisher's send policy is non-inline, flush all outsanding messages.
int	getMaxBatchCount() Returns the maximum batch count of a non-inline publisher.
int	getSendPolicy() Returns the send policy of a publisher.
void	send(Message msg) Send a message, one-to-many.
void	send(Message[] messages) Send an array of messages, one-to-many.
void	send(Message[] messages, int messageCount) Send a subset of messages from an array of messages.
void	sendReply(Message reply, Message request) Send a reply message to a requester.
Message	sendRequest(Message request, double timeout) Send a request and wait for reply.
void	sendToInbox(Inbox inbox, Message msg) Send an inbox message to an inbox.

Field Detail

PROPERTY_STRING_REPLY_ENDPOINT

static final java.lang.String PROPERTY_STRING_REPLY_ENDPOINT

Property name for a publisher reply endpoint; string.

For Publisher.sendRequest this specifies the endpoint on which the reply is received.

See Also:

Realm.createPublisher, Constant Field Values

PROPERTY_STRING_LABEL

static final java.lang.String PROPERTY_STRING_LABEL

Property name for a publisher label; string.

It is good practice to include this property in every publisher create call. Monitoring data incorporates these labels so administrators can identify and distinguish among publishers. Use labels that reveal the unique role and identity of each publisher within the application program.

If a non-inline persistence publisher fails to persist a message, the resulting advisory will include the publisher label. See Advisory.NAME_NONINLINE_SEND_LOSS.

See Also:

Realm.createPublisher, Constant Field Values

SEND_INLINE

static final int SEND_INLINE

Publish with low latency; integer.

If this value is set for property PROPERTY_INT_SEND_POLICY, then publish calls send(Message msg) and send(Message messages []) send messages immediately to reduce latency.

See Also:

Constant Field Values

SEND_NON_INLINE

static final int SEND_NON_INLINE

Publish with high throughput; integer.

If this value is set for property PROPERTY_INT_SEND_POLICY, then the publish call send(Message msg) may batch messages in the background for improved throughput.

See Also:

Constant Field Values

PROPERTY_INT_SEND_POLICY

static final java.lang.String PROPERTY_INT_SEND_POLICY

Publisher send policy; string.

Optimize the publisher for lower latency or greater throughput.

Values:

• SEND_INLINE Send the message immediately, to reduce latency.
• SEND_NON_INLINE Buffer and batch messages before sending to help improve throughput.

When publishing to a store, and the administrator has configured publisher mode store_confirm_send for the store, the inline send policy causes send(Message msg) and send(Message messages []) to block until the message(s) have been successfully persisted, or until a failure occurs.

When publishing to a store, and the administrator has configured publisher mode store_confirm_send for the store, the non-inline send policy changes the behavior of send(Message msg).

• Calls to send(Message msg) return immediately, unless the maximum batch count has been reached. The message will be persisted in the background. See PROPERTY_INT_MAX_BATCH_COUNT.
• If a failure occurs in the background, the next call to send(Message msg) or flush() will raise an exception. When this happens the application must assume that the most recent messages, up to the maximum batch count and including the message passed to send(Message msg), have been lost. See PROPERTY_INT_MAX_BATCH_COUNT.
• When the application calls close(), some messages may not have been persisted. In this case the close call may linger for some time before discarding the messages. See PROPERTY_DOUBLE_PERSISTENCE_CLOSE_LINGER.
• Applications may call flush() to wait for all outstanding messages to be persisted.
• If a failure occurs in the background, an advisory will be generated. This is a hint to the application that an error has occurred, and that a call to flush() will raise an exception. See Advisory.NAME_NONINLINE_SEND_LOSS.

The getSendPolicy() call returns the value currently in effect.

See Also:

Realm.createPublisher, Constant Field Values

PROPERTY_BOOL_RELEASE_MSGS_TO_SEND

static final java.lang.String PROPERTY_BOOL_RELEASE_MSGS_TO_SEND

Ownership of outbound messages; boolean.

When false or absent, client program code retains ownership of outbound messages that it sends through this publisher.

When true, the FTL library accepts ownership of outbound messages that the client sends through this publisher. Client code releases the message object when it invokes the send call; from that moment onward, client code must not reference the message object, because the FTL library can destroy the message object at any time.

Client code can release a message only if client owns the message. In particular, if a subscriber does not release its messages to the callback, then the callback must not send it through a publisher that releases messages. (See Subscriber.PROPERTY_BOOL_RELEASE_MSGS_TO_CALLBACK .)

See Also:

Realm.createPublisher, Constant Field Values

PROPERTY_DOUBLE_PERSISTENCE_RETRY_DURATION

static final java.lang.String PROPERTY_DOUBLE_PERSISTENCE_RETRY_DURATION

Retry duration for persistent publisher operations; double.

When Realm.createPublisher(java.lang.String) or send(com.tibco.ftl.Message) cannot access the persistence server (usually because of network failure or quorum unavailability), they can automatically retry the interaction. The value of this property overrides the retry behavior of the server. Supply it to the publisher create call.

Values:

• 0 No retry. The call raises an exception.
• -1 Synchronously retry the interaction until it succeeds. The call returns only upon success.
• n (Any positive double value) Retry the interaction for n seconds. Return upon success or raise an exception after timeout.

Closing the publisher or the realm supersedes and cancels retry behavior.

See Also:

Realm.createPublisher, Constant Field Values

PROPERTY_INT_MAX_BATCH_COUNT

static final java.lang.String PROPERTY_INT_MAX_BATCH_COUNT

Maximum batch count for non-inline publishers; integer.

When a persistence publisher is configured for non-inline send, this is the maximum number of messages that may be in flight to the persistence service at any given time. When this limit is reached, send(Message msg) blocks until some messages can be persisted, or a failure occurs. The default value is 100.

The getMaxBatchCount() call returns the value currently in effect.

See Also:

Realm.createPublisher, Constant Field Values

PROPERTY_DOUBLE_PERSISTENCE_CLOSE_LINGER

static final java.lang.String PROPERTY_DOUBLE_PERSISTENCE_CLOSE_LINGER

Linger duration for persistent publisher close operation; double.

When a persistence publisher is configured for non-inline send, and a call to close() is made while there are still messages waiting to be persisted, the call can be configured to wait for some time before closing the publisher. If the linger period elapses, and the messages have not been successfully persisted, the messages will be discarded. Set this property to control the linger behavior of close(). The default value is 30 seconds.

Values:

• 0 Close the publisher immediately.
• -1 Close the publisher only after it successfully persisted all outstanding messages
• n (Any positive double value) Wait for the publisher to persist outstanding messages for at most n seconds. Proceed with closing the publisher upon success or timeout, whichever comes first.

Closing the realm supersedes and cancels linger behavior.

See Also:

Realm.createPublisher, Constant Field Values

Method Detail

send

void send(Message msg)
   throws FTLException

Send a message, one-to-many.

If the administrator has configured publisher mode store_confirm_send for the store, a persistence publisher may block in this call until the message has been persisted. Otherwise the call returns immediately, and the message may or may not be stored.

For persistence publishers, the exact semantics depend on the send policy. See PROPERTY_INT_SEND_POLICY.

Parameters:

msg - The method sends this message.

Throws:

FTLException

send

void send(Message[] messages)
   throws FTLException

Send an array of messages, one-to-many.

The application sends each message in the array, in order.

Sending an array of messages eliminates the overhead cost of a separate call for each message.

If the administrator has configured publisher mode store_confirm_send for the store, a persistence publisher will block in this call until all messages have been persisted. Otherwise the call returns immediately, and the messages may or may not be stored.

Parameters:

messages - The method sends all the messages from this array.

Throws:

FTLException

send

void send(Message[] messages,
          int messageCount)
   throws FTLException

Send a subset of messages from an array of messages.

The application sends messageCount messages from the array, in order.

Sending an array of messages eliminates the overhead cost of a separate call for each message.

If the administrator has configured publisher mode store_confirm_send for the store, a persistence publisher will block in this call until all messages have been persisted. Otherwise the call returns immediately, and the messages may or may not be stored.

Parameters:

messages - The method sends messages from this array.

messageCount - Supply the number of messages to send.

Throws:

FTLException

sendToInbox

void sendToInbox(Inbox inbox,
                 Message msg)
          throws FTLException

Send an inbox message to an inbox.

Because inbox messages do not trigger the content matchers of other subscribers on the endpoint, they are an efficient way to target a message to a specific destination. For example, you might use an inbox message to query a specific data source, or to reply to a query.

For details about getting an inbox, see Realm.createInboxSubscriber, Message.getInbox and Inbox.

Parameters:

inbox - The method sends the message to this inbox.

msg - The method sends this message.

Throws:

FTLException

sendRequest

Message sendRequest(Message request,
                    double timeout)
             throws FTLException

Send a request and wait for reply.

Send a request and wait for a reply within a specified timeout.

Parameters:

request - The request message.

timeout - The maximum time (in seconds) to wait for a reply.

Throws:

FTLException

sendReply

void sendReply(Message reply,
               Message request)
        throws FTLException

Send a reply message to a requester.

Upon receiving a request message, send a reply message to the requester.

Parameters:

reply - The reply message.

request - The original request message.

Throws:

FTLException

close

void close()
    throws FTLException

Close a publisher.

Closing a publisher releases all the resources associated with it (for example, transport resources that are not used in other endpoints).

Throws:

FTLException

flush

void flush()
    throws FTLException

When the publisher's send policy is non-inline, flush all outsanding messages.

When a persistence publisher is configured for non-inline send, calls to send(Message msg) may return before the message is persisted. Applications may call this function to ensure that all outstanding messages have been persisted (for example, if the application intends to close the publisher). This function blocks until all messages have been persisted, or until a failure occurs. If a failure occurs, this call will raise an exception.

Throws:

FTLException

getSendPolicy

int getSendPolicy()
           throws FTLException

Returns the send policy of a publisher.

Returns the send policy that is in effect for this publisher. Applications may use this call to determine appropriate behavior if a persistence publisher fails to persist a message.

See PROPERTY_INT_SEND_POLICY.

Returns:

the send policy

Throws:

FTLException

getMaxBatchCount

int getMaxBatchCount()
              throws FTLException

Returns the maximum batch count of a non-inline publisher.

Returns the maximum batch count that is in effect for this publisher. Applications may use this call to determine appropriate behavior if a non-inline persistence publisher fails to persist a message.

See PROPERTY_INT_MAX_BATCH_COUNT.

Returns:

the maximum batch count

Throws:

FTLException