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Use cases overview

At the core of the platform is the use case. A use case is defined by user who understand the required computation and output criteria needed by the business

Use case example

Below is a fully use case that performs a basic window aggregation computation using a metrics engine and tumbling window before publishing a filter stream of events to a connected publisher.
stream:
name: tumblingWindowQuoteStream
eventTimeType: EVENT_TIME
sources:
- nasdaq_quotes_stream
initialisation:
sql import:
schema: fxrates
parquet:
- table: quote
asView: false
files: [ 'fxrates.parquet' ]
drop table: true
index:
fields: [ 'ccy' ]
unique: false
processing unit:
metrics engine:
policy:
timeUnit: MINUTES
frequency: 1
startup delay: 2
foreach metric compute:
metrics:
- name: BidMovingAverage
metric key: symbol
table definition: standardQuoteAnalyticsStream.BidMovingAverage (symbol VARCHAR, avg_bid_min FLOAT, avg_bid_avg FLOAT,avg_bid_max FLOAT)
query:
SELECT symbol,
AVG(bid_MAX) AS mt_avg_bid_min,
AVG(bid_MAX) AS mt_avg_bid_max
OVER (
PARTITION BY symbol ORDER BY eventTime ASC
RANGE BETWEEN INTERVAL 1 SECONDS PRECEDING
AND INTERVAL 1 SECONDS FOLLOWING)
AS 'bid max Moving Average'
FROM quotesStream.tumblingQuoteAnalytics_View
ORDER BY 1;
truncate on start: true
compaction:
frequency: 8
timeUnit: HOURS
pipeline:
- filter:
expression: "symbol != 'A'"
- timeWindow:
emittingEventType: tumblingQuoteAnalytics
aggregateFunctions:
MIN: [ask, bid]
MAX: [ask, bid]
policy:
type: tumblingTime
windowSize: 5000
emit:
eventType: windowQuoteEvent
select: "symbol, ask_MIN, ask_MAX, bid_MIN, bid_MAX, BidMovingAverage.avg_bid_max;WHERE symbol=${symbol}"
having: "symbol !='A'"
group by:
- symbol

DSL Elements

Initialisation

Joule provide the ability to prime the system with static reference data at startup. Read the initialisation documentation for further information.

Procession Unit

The main objective of the platform was to build use cases easliy and clearly. To understand how to build use case read the processing unit documentation.

Emit

Ability to select required output feilds and to perform a final filter before publishing events to downstream systems. Read the emit documentation for further information.

Group by

Provides the ability to group similair events to perform a computation in order to reduce the overall downstream output. Read the group by documentation for more information.