Integrate Solr with real-time stream processing applications

INTEGRATE SOLR WITH REAL-TIME STREAM PROCESSING APPLICATIONS

Timothy Potter@thelabdude

linkedin.com/thelabdude

whoami

independent consultant search / big data projectssoon to be joining engineering team @LucidWorks

co-author Solr In Actionpreviously big data architect Dachis Group

my storm story

re-designed a complex batch-oriented indexing pipeline based on Hadoop (Oozie, Pig, Hive,

Sqoop) to real-time storm topology

agenda

walk through how to develop a storm topologycommon integration points with Solr

(near real-time indexing, percolator, real-time get)

examplelisten to click events from 1.usa.gov URL

shortener (bit.ly) to determine trending US government sitesstream of click events:

http://developer.usa.gov/1usagov

http://www.smartgrid.gov -> http://1.usa.gov/ayu0Ru

beyond word count

tackle real challenges you’ll encounter when developing a storm topology

and what about ... unit testing, dependency injection, measure runtime behavior of your components,

separation of concerns, reducing boilerplate, hiding complexity ...

storm

open source distributed computation systemscalability, fault-tolerance, guaranteed

message processing (optional)

storm primitives

• tuple: ordered list of values • stream: unbounded sequence of tuples• spout: emit a stream of tuples (source)• bolt: performs some operation on each tuple• topology: dag of spouts and tuples

solution requirements

• receive click events from 1.usa.gov stream• count frequency of pages in a time window• rank top N sites per time window• extract title, body text, image for each link• persist rankings and metadata for

visualization

trending snapshot (sept 12, 2013)

Solr

MetricsDB

EnrichLinkBolt

SolrIndexing

Bolt

1.usa.govSpout

RollingCountBolt

IntermediateRankings

Bolt

TotalRankings

Bolt

embed.lyAPI

fieldgrouping

bit.ly hash

fieldgrouping

bit.ly hash

globalgrouping

PersistRankings

Bolt

fieldgrouping

objglobal

grouping

provided by in thestorm-starter project

data store

bolt

spout

stream

grouping

stream grouping

• shuffle: random distribution of tuples to all instances of a bolt

• field(s): group tuples by one or more fields in common

• global: reduce down to one• all: replicate stream to all instances of a bolt

source: https://github.com/nathanmarz/storm/wiki/Concepts

useful storm concepts

• bolts can receive input from many spouts• tuples in a stream can be grouped together• streams can be split and joined• bolts can inject new tuples into the stream• components can be distributed across a cluster at a

configurable parallelism level• optionally, storm keeps track of each tuple emitted by

a spout (ack or fail)

tools

• Spring framework – dependency injection, configuration, unit testing, mature, etc.

• Groovy – keeps your code tidy and elegant• Mockito – ignore stuff your test doesn’t care about• Netty – fast & powerful NIO networking library• Coda Hale metrics – get visibility into how your bolts

and spouts are performing (at a very low-level)

spout

easy! just produce a stream of tuples ...

and ... avoid blocking when waiting for more data, ease off throttle if topology is not processing fast enough, deal with failed tuples, choose if it should use message Ids for each tuple emitted, data

model / schema, etc ...

SpringBoltSpringSpout

StreamingDataAction

(POJO)

StreamingDataProvider

(POJO)

Spring container (1 per topology per JVM)

SpringDependency

Injection

JDBC WebService

Hide complexityof implementingStorm contract

developerfocuses onbusiness

logic

streaming data providerclass OneUsaGovStreamingDataProvider implements StreamingDataProvider, MessageHandler {

MessageStream messageStream

...

void open(Map stormConf) { messageStream.receive(this) }

boolean next(NamedValues nv) { String msg = queue.poll() if (msg) { OneUsaGovRequest req = objectMapper.readValue(msg, OneUsaGovRequest) if (req != null && req.globalBitlyHash != null) { nv.set(OneUsaGovTopology.GLOBAL_BITLY_HASH, req.globalBitlyHash) nv.set(OneUsaGovTopology.JSON_PAYLOAD, req) return true } }

return false }

void handleMessage(String msg) { queue.offer(msg) }

Spring Dependency Injection

non-blocking call to get thenext message from 1.usa.gov

use Jackson JSON parserto create an object from theraw incoming data

jackson json to java@JsonIgnoreProperties(ignoreUnknown = true)class OneUsaGovRequest implements Serializable {

@JsonProperty("a") String userAgent;

@JsonProperty("c") String countryCode;

@JsonProperty("nk") int knownUser;

@JsonProperty("g") String globalBitlyHash;

@JsonProperty("h") String encodingUserBitlyHash;

@JsonProperty("l") String encodingUserLogin;

...}

Spring converts json to java object for you: <bean id="restTemplate" class="org.springframework.web.client.RestTemplate"> <property name="messageConverters"> <list> <bean id="messageConverter” class="...json.MappingJackson2HttpMessageConverter"> </bean> </list> </property> </bean>

spout data provider spring-managed bean

<bean id="oneUsaGovStreamingDataProvider" class="com.bigdatajumpstart.storm.OneUsaGovStreamingDataProvider"> <property name="messageStream"> <bean class="com.bigdatajumpstart.netty.HttpClient"> <constructor-arg index="0" value="${streamUrl}"/> </bean> </property></bean>

builder.setSpout("1.usa.gov-spout", new SpringSpout("oneUsaGovStreamingDataProvider", spoutFields), 1)

Note: when building the StormTopology to submit to Storm, you do:

class OneUsaGovStreamingDataProviderTest extends StreamingDataProviderTestBase {

@Test void testDataProvider() {

String jsonStr = '''{ "a": "user-agent", "c": "US", "nk": 0, "tz": "America/Los_Angeles", "gr": "OR", "g": "2BktiW", "h": "12Me4B2", "l": "usairforce", "al": "en-us", "hh": "1.usa.gov", "r": "http://example.com/foo", ... }'''

OneUsaGovStreamingDataProvider dataProvider = new OneUsaGovStreamingDataProvider() dataProvider.setMessageStream(mock(MessageStream)) dataProvider.open(stormConf) // Config setup in base class dataProvider.handleMessage(jsonStr)

NamedValues record = new NamedValues(OneUsaGovTopology.spoutFields) assertTrue dataProvider.next(record) ... }}

spout data provider unit test

mock json to simulatedata from 1.usa.gov feed

use Mockito to satisfydependencies not neededfor this test

asserts to verifydata provider works correctly

rolling count bolt

• counts frequency of links in a sliding time window

• emits topN in current window every M seconds

• uses tick tuple trick provided by Storm to emit every M seconds (configurable)

• provided with the storm-starter project

http://www.michael-noll.com/blog/2013/01/18/implementing-real-time-trending-topics-in-storm/

• calls out to embed.ly API• caches results locally in the bolt

instance• relies on field grouping (incoming

tuples)• outputs data to be indexed in Solr• benefits from parallelism to enrich more

links concurrently (watch those rate limits)

enrich link metadata bolt

embed.ly serviceclass EmbedlyService {

@Autowired RestTemplate restTemplate

String apiKey

private Timer apiTimer = MetricsSupport.timer(EmbedlyService, "apiCall")

Embedly getLinkMetadata(String link) { String urlEncoded = URLEncoder.encode(link,"UTF-8") URI uri = new URI("https://api.embed.ly/1/oembed?key=${apiKey}&url=${urlEncoded}")

Embedly embedly = null MetricsSupport.withTimer(apiTimer, { embedly = restTemplate.getForObject(uri, Embedly) }) return embedly }}

simple closure to time ourrequests to the Web service

integrate coda hale metrics

• capture runtime behavior of the components in your topology

• Coda Hale metrics - http://metrics.codahale.com/

• output metrics every N minutes• report metrics to JMX, ganglia, graphite, etc

metrics

-- Meters ----------------------------------------------------------------------EnrichLinkBoltLogic.solrQueries count = 97 mean rate = 0.81 events/second 1-minute rate = 0.89 events/second 5-minute rate = 1.62 events/second 15-minute rate = 1.86 events/second

SolrBoltLogic.linksIndexed count = 60 mean rate = 0.50 events/second 1-minute rate = 0.41 events/second 5-minute rate = 0.16 events/second 15-minute rate = 0.06 events/second

-- Timers ----------------------------------------------------------------------EmbedlyService.apiCall count = 60 mean rate = 0.50 calls/second 1-minute rate = 0.40 calls/second 5-minute rate = 0.16 calls/second 15-minute rate = 0.06 calls/second min = 138.70 milliseconds max = 7642.92 milliseconds mean = 1148.29 milliseconds stddev = 1281.40 milliseconds median = 652.83 milliseconds 75% <= 1620.96 milliseconds ...

storm cluster concepts

• nimbus: master node (~job tracker in Hadoop)• zookeeper: cluster management / coordination• supervisor: one per node in the cluster to manage

worker processes• worker: one or more per supervisor (JVM process)• executor: thread in worker• task: work performed by a spout or bolt

Worker 1 (port 6701)

Nimbus

Supervisor (1 per node)

TopologyJAR

Node 1

JVM process

executor(thread) ... N workers

... M nodes

Each component (spout or bolt)is distributed across a cluster ofworkers based on a configurableparallelism

Zookeeper

@Override StormTopology build(StreamingApp app) throws Exception { ... TopologyBuilder builder = new TopologyBuilder()

builder.setSpout("1.usa.gov-spout", new SpringSpout("oneUsaGovStreamingDataProvider", spoutFields), 1)

builder.setBolt("enrich-link-bolt", new SpringBolt("enrichLinkAction", enrichedLinkFields), 3) .fieldsGrouping("1.usa.gov-spout", globalBitlyHashGrouping)

...

parallelism hint tothe framework

(can be rebalanced)

solr integration points

• real-time get • near real-time indexing (NRT)• percolate (match incoming docs to pre-

existing queries)

real-time getuse Solr for fast lookups by document ID

class SolrClient {

@Autowired SolrServer solrServer

SolrDocument get(String docId, String... fields) { SolrQuery q = new SolrQuery() q.setRequestHandler("/get") q.set("id", docId) q.setFields(fields) QueryRequest req = new QueryRequest(q) req.setResponseParser(new BinaryResponseParser()) QueryResponse rsp = req.process(solrServer) return (SolrDocument)rsp.getResponse().get("doc") }}

send the request to the “get” request handler

near real-time indexing

• If possible, use CloudSolrServer to route documents directly to the correct shard leaders (SOLR-4816)

• Use <openSearcher>false</openSearcher> for auto “hard” commits

• Use auto soft commits as needed• Use parallelism of Storm bolt to distribute indexing

work to N nodeshttp://searchhub.org/2013/08/23/understanding-transaction-logs-softcommit-and-commit-in-sorlcloud/

percolate

• match incoming documents to pre-configured queries (inverted search)– example: Is this tweet related to campaign Y for brand X?

• use storm’s distributed computation support to evaluate M pre-configured queries per doc

two possible approaches

• Lucene-only solution using MemoryIndex– See presentation by Charlie Hull and Alan Woodward

• EmbeddedSolrServer– Full solrconfig.xml / schema.xml– RAMDirectory– Relies on Storm to scale up documents / second– Easy solution for up to a few thousand queries

TwitterSpout

PercolatorBolt 1

EmbeddedSolrServer

Pre-configuredqueries stored in

a database

PercolatorBolt N

EmbeddedSolrServer

... Could be 100’s of these

randomstream

grouping ZeroMQpub/sub to pushquery changesto percolator

tick tuples

• send a special kind of tuple to a bolt every N seconds

if (TupleHelpers.isTickTuple(input)) { // do special work }

used in percolator to delete accumulated documents every minute or so ...

references• Storm Wiki

• https://github.com/nathanmarz/storm/wiki/Documentation

• Overview: Krishna Gade• http://www.slideshare.net/KrishnaGade2/storm-at-twitter

• Trending Topics: Michael Knoll• http://www.michael-noll.com/blog/2013/01/18/implementing-real-

time-trending-topics-in-storm/

• Understanding Parallelism: Michael Knoll• http://www.michael-noll.com/blog/2012/10/16/understanding-the-

parallelism-of-a-storm-topology/

get the code: https://github.com/thelabdude/lsrdublin

Q & A

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