net.fortytwo.stream

Interface StreamProcessor<Q,I,S>

Type Parameters:

Q - the query type

I - the input data type

S - the solution data type

All Known Implementing Classes:

BasicStreamProcessor

public interface StreamProcessor<Q,I,S>

Interface for a continuous query engine with a publish/subscribe API. A query engine receives queries in advance of input data, computing solutions incrementally.

Author:

Joshua Shinavier (http://fortytwo.net)

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static class	StreamProcessor.IncompatibleQueryException An exception thrown when a valid query is incompatible with a QueryEngine implementation
static class	StreamProcessor.InvalidQueryException An exception thrown when a query is not syntactically valid

Field Summary

Fields

Modifier and Type	Field and Description
static int	INFINITE_TTL A special time-to-live value for statements or queries which are valid indefinitely.
static long	NEVER_EXPIRE A special value representing an infinitely remote expiration time

Method Summary

Modifier and Type	Method and Description
boolean	addInputs(int ttl, I... inputs) Adds new input data to this query engine.
Subscription	addQuery(int ttl, Q query, java.util.function.BiConsumer<S,Long> consumer) Adds a new query subscription to this query engine
void	clear() Removes all triple patterns along with their associated partial solutions, queries, and subscriptions
void	setClock(java.util.function.Supplier<Long> clock) Sets the clock used by this query engine to determine the expiration of queries and solutions, overriding a default clock (e.g.

Field Detail

INFINITE_TTL

static final int INFINITE_TTL

A special time-to-live value for statements or queries which are valid indefinitely.

See Also:

Constant Field Values

NEVER_EXPIRE

static final long NEVER_EXPIRE

A special value representing an infinitely remote expiration time

See Also:

Constant Field Values

Method Detail

clear

void clear()

Removes all triple patterns along with their associated partial solutions, queries, and subscriptions

addQuery

Subscription addQuery(int ttl,
                      Q query,
                      java.util.function.BiConsumer<S,Long> consumer)
               throws IOException,
                      StreamProcessor.IncompatibleQueryException,
                      StreamProcessor.InvalidQueryException

Adds a new query subscription to this query engine

Parameters:

ttl - the time-to-live of the generated subscription, in seconds. If ttl is greater than 0, the query has a finite lifetime and will be automatically unregistered at the end of that lifetime. Note: the query engine may be configured to reject a ttl which is too high, including 0 (infinite).

query - the query to add

consumer - a handler for future query solutions together with their expiration time

Returns:

a subscription for computation of future query solutions

Throws:

StreamProcessor.InvalidQueryException - if the query is not valid

StreamProcessor.IncompatibleQueryException - if the query is valid, but it is not supported by this query engine

IOException - if there is a problem communicating with this query engine (for example, if there are network operations involved)

addInputs

boolean addInputs(int ttl,
                  I... inputs)

Adds new input data to this query engine. Depending on the queries registered with this engine, the inputs will either be discarded as irrelevant to the queries, trigger the creation of partial solutions which are stored in anticipation of further inputs, or trigger the production query solutions.

Parameters:

ttl - the time-to-live of the inputs, in seconds. If ttl is greater than 0, any partial solutions which are computed in response to those inputs have a finite lifetime, and will expire from the index at the end of that lifetime.

inputs - the input data to add. Inputs are added in array order

Returns:

whether the addition of the inputs changed the state of the stream processor; some inputs may pass through and have no effect, while others are used in query answering

setClock

void setClock(java.util.function.Supplier<Long> clock)

Sets the clock used by this query engine to determine the expiration of queries and solutions, overriding a default clock (e.g. based on System.currentTimeMillis()) The supplied clock must supply the real or virtual current time, in milliseconds. Values produced must be non-negative and monotonically non-decreasing.

Parameters:

clock - the new clock