Driveline Python SDK

At the core of the Python SDK is the class DrivelineClient.

import asyncio

from driveline import DrivelineClient, run_async

async def main():
    async with DrivelineClient('ws://127.0.0.1:8080') as client:

        # list all streams
        async for stream_name in await client.list_streams('*'):
            print('found stream:', stream_name)

        # list all keys is the document store
        async for key_name in await client.list_keys('*'):
            print('found document with key', key_name)


        # store a document in the document store
        await client.store('key/1', dict(title='Welcome', body='Hello, world!'))

        # load a key from the document store
        future_record = await client.load('key/1')
        record = await future_record
        print('document associated with key/1 is:', record.record, 'id:', record.record_id)

        # remove all records in the document store with keys matching 'key/...'
        await client.removeMatches('key/*')

        # run a live query against a stream. 
        # We want all records that have an odd index
        def query_handler(res):
            print('query returned record:', res.record, 'id:', res.record_id)
        query = await client.continuous_query('SELECT * FROM STREAM my_stream where index % 1 == 1', query_handler)


        # stop the query
        await asyncio.sleep(10)
        await client.cancel(query)

        # quit
        await client.close()

if __name__ == '__main__':
    run_async(main())

DQL Driveline Query Language

Query syntax

Basic syntax

SELECT <selector> FROM STREAM <stream> [WHERE <expression>]
SELECT * FROM STREAM stream_1
SELECT * FROM STREAM stream_1 WHERE key=value
SELECT time AS t,(2+3) AS five FROM STREAM stream_1 WHERE age BETWEEN 21 AND 25 OR name LIKE 'Joe%'

DQL supports standard SQL query syntax, excluding Joins and Aggregates. This means DQL can be used for all forms of data filtering and partitioning of data over live streams.

KV query

SELECT <selector> FROM <string-key-name-expression> [WHERE <expression>]
SELECT * FROM 'users/*' WHERE color='red'

Multi key query is a DQL extension that lets you subscribe to multiple event streams, automatically subscribing to new streams as they form, based on the stream name expression. Stream name expression use file-system/Pythong Glob, with ?, * and ** serving as the wildcard match characters.

ECMAScript Object Notation (JavaScript extensions)

SELECT {time,name:user.name,phone_number:user.phone.mobile.number,original:{...*}} FROM stream

With inputs of the form:

{time:123, user: {name:'joe', phone: {mobile: {number:'1-800-123-4567'}}}}

Results in:

{time:123,name:'joe',phone_number:'1-800-123-4567',original:{time:123,user:phone:{...}}}

Operators

The following table summarizes all language operators in order of precedence

Built-in functions