com.tibco.as.space.browser

Interface Browser

public interface Browser

A Browser is used to iterate over the entries in a Space as opposed to an EventBrowser which is used to iterate over events associated with the entries in a Space (e.g. put, take, expire). A Browser is created by calling Metaspace.browse(java.lang.String, com.tibco.as.space.browser.BrowserDef.BrowserType).

All Browsers implement a next() and a stop() method but unlike traditional iterators, a Browser does not have a hasNext() method. Instead Browsers have a timeout which is the amount of time that the next() method call will block while waiting for a new entry to be added to the Space.

There are different types of Browsers. What the next() method does depends upon the type of the Browser:

• A GET Browser's next() method gets the next entry in the space and returns it.
• A TAKE Browser's next() method takes the next entry from the space and returns it.
• A LOCK Browser's next() method locks the next entry in the space and returns it.

TAKE and LOCK Browsers are always consistent with the Space. For example, if two separate TAKE Browsers are browsing the same Space (regardless of their location), they will NEVER be able to take the same entry. Browsers are continuously updated (coherent) with the real-time changes occurring in the Space being browsed (unless the Browser's time scope is SNAPSHOT).

Browsers have several mechanisms which help to limit the entries being browsed.

The time scope setting limits the set of entries being iterated over based upon the time the Browser is created.

• Time scope ALL means that all of the entries stored in the Space will be browsed.
• Time scope NEW means that only the entries stored in the Space after the Browser creation time, will be browsed.
• Time scope SNAPSHOT means that only the entries stored in the Space at the time the Browser is created will be browsed.

The distribution scope setting limits the set of entries or events being iterated over based upon where they are stored in the space.

• Distribution scope ALL means that all of the entries in the Space will be browsed.
• Distribution scope SEEDED means that only the entries stored by the invoking member will be browsed.

An optional filter can be applied to Browsers to further refine the set of entries being iterated over.

Browsers do not guarantee any order of presentation of the entries.

See Also:

BrowserDef, EventBrowser

Method Summary

Methods

Modifier and Type	Method and Description
java.util.Map<Member,java.lang.String>	getQueryLogs() Deprecated.
BrowserDef.BrowserType	getType() Retrieve the type of the Browser.
boolean	isPartialResult() Indicates whether the results are incomplete due to query limit.
Tuple	next() Retrieve the next entry from the Space.
void	query(java.lang.String filter)
void	reset()
long	size() actual size of the browser if SNAPSHOT and prefetch_all is used otherwise estimated size of tuples to be returned from the browser
void	stop() Stop the Browser.

Method Detail

query

void query(java.lang.String filter)
           throws ASException

Parameters:

filter -

Throws:

ASException

reset

void reset()
           throws ASException

Throws:

ASException

next

Tuple next()
           throws ASException

Retrieve the next entry from the Space.

Returns:

A Tuple containing the values from the next entry in the Space.

Throws:

ASException - An exception is thrown if an error occurs while retrieving the values of the entry.

stop

void stop()
          throws ASException

Stop the Browser.

Throws:

ASException - An exception is thrown if an error occurs while trying to stop the Browser.

getType

BrowserDef.BrowserType getType()

Retrieve the type of the Browser.

Returns:

The type of the Browser. For example, GET, LOCK or TAKE.

getQueryLogs

@Deprecated
java.util.Map<Member,java.lang.String> getQueryLogs()

Deprecated.

Retrieve the query execution logs per seeder node.

Returns:

A map of Space Members who are seeders and the location of their query logs.

isPartialResult

boolean isPartialResult()

Indicates whether the results are incomplete due to query limit.

Returns:

true if the results are limited due to limit, false otherwise

size

long size()

actual size of the browser if SNAPSHOT and prefetch_all is used otherwise estimated size of tuples to be returned from the browser

Returns:

size of estimated number of tuples