Application Architectures with Hadoop

Application
Architectures with
Hadoop
Toronto Hadoop Users Group
December 18, 2014
tiny.cloudera.com/app-arch-toronto
Mark Grover | @mark_grover

2
About the book
•  @hadooparchbook
•  hadooparchitecturebook.com
•  github.com/hadooparchitecturebook
•  slideshare.com/hadooparchbook
©2014 Cloudera, Inc. All Rights Reserved.

3
About Me
•  Mark
–  Software Engineer
–  Committer on Apache Bigtop, committer and PPMC member on Apache
Sentry (incubating).
–  Contributor to Hadoop, Hive, Spark, Sqoop, Flume

4
Case Study
Clickstream Analysis

5
Analytics

6
Analytics

7
Web Logs – Combined Log Format
244.157.45.12 - - [17/Oct/2014:21:08:30 ] "GET /seatposts HTTP/1.0"
200 4463 "http://bestcyclingreviews.com/top_online_shops" "Mozilla/
5.0 (Macintosh; Intel Mac OS X 10_9_2) AppleWebKit/537.36 (KHTML,
like Gecko) Chrome/36.0.1944.0 Safari/537.36”
244.157.45.12 - - [17/Oct/2014:21:59:59 ] "GET /Store/cart.jsp?
productID=1023 HTTP/1.0" 200 3757 "http://www.casualcyclist.com"
"Mozilla/5.0 (Linux; U; Android 2.3.5; en-us; HTC Vision Build/
GRI40) AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile
Safari/533.1”

8
Clickstream Analytics
244.157.45.12 - - [17/Oct/
2014:21:08:30 ] "GET /seatposts
HTTP/1.0" 200 4463 "http://
bestcyclingreviews.com/
top_online_shops" "Mozilla/5.0
(Macintosh; Intel Mac OS X 10_9_2)
AppleWebKit/537.36 (KHTML, like
Gecko) Chrome/36.0.1944.0 Safari/
537.36”

9
Challenges of Hadoop Implementation

10
Challenges of Hadoop Implementation

11
Hadoop Architectural Considerations
•  Storage managers?
–  HDFS? HBase?
•  Data storage and modeling:
–  File formats? Compression? Schema design?
•  Data movement
–  How do we actually get the data into Hadoop? How do we get it out?
•  Metadata
–  How do we manage data about the data?
•  Data access and processing
–  How will the data be accessed once in Hadoop? How can we transform it? How do
we query it?
•  Orchestration
–  How do we manage the workflow for all of this?

12
Architectural
Considerations
Data Storage and Modeling

13
Data Modeling Considerations
•  We need to consider the following in our architecture:
–  Storage layer – HDFS? HBase? Etc.
–  File system schemas – how will we lay out the data?
–  File formats – what storage formats to use for our data, both raw and
processed data?
–  Data compression formats?

14
Architectural
Considerations
Data Modeling – Storage Layer

15
Data Storage Layer Choices
•  Two likely choices for raw data:

16
Data Storage Layer Choices
•  Stores data directly as files
•  Fast scans
•  Poor random reads/writes
•  Stores data as Hfiles on
HDFS
•  Slow scans
•  Fast random reads/writes

17
Data Storage – Storage Manager Considerations
•  Incoming raw data:
–  Processing requirements call for batch transformations across multiple
records – for example sessionization.
•  Processed data:
–  Access to processed data will be via things like analytical queries – again
requiring access to multiple records.
•  We choose HDFS
–  Processing needs in this case served better by fast scans.

18
Architectural
Considerations
Data Modeling – Data Storage Format

19
Our Format Choices…
•  Raw data
–  Avro with Snappy
•  Processed data
–  Parquet

20
Architectural
Considerations
Data Modeling – HDFS Schema Design

21
Recommended HDFS Schema Design
•  How to lay out data on HDFS?

22
Recommended HDFS Schema Design
/user/<username> - User specific data, jars, conf files
/etl – Data in various stages of ETL workflow
/tmp – temp data from tools or shared between users
/data – shared data for the entire organization
/app – Everything but data: UDF jars, HQL files, Oozie workflows

23
Architectural
Considerations
Data Modeling – Advanced HDFS Schema
Design

24
Partitioning
dataset
col=val1/file.txt
col=val2/file.txt
…
col=valn/file.txt
dataset
file1.txt
file2.txt
…
filen.txt
Un-partitioned HDFS
directory structure
Partitioned HDFS
directory structure

25
Partitioning considerations
•  What column to partition by?
–  Don’t have too many partitions (<10,000)
–  Don’t have too many small files in the partitions
–  Good to have partition sizes at least ~1 GB
•  We’ll partition by timestamp. This applies to both our raw and
processed data.

26
Architectural
Considerations
Data Ingestion

27
File Transfers
•  “hadoop fs –put <file>”
•  Reliable, but not
resilient to failure.
•  Other options are
mountable HDFS, for
example NFSv3.

28
Streaming Ingestion
•  Flume
–  Reliable, distributed, and available system for efficient collection, aggregation
and movement of streaming data, e.g. logs.
•  Kafka
–  Reliable and distributed publish-subscribe messaging system.

29
Flume vs. Kafka
•  Purpose built for
Hadoop data ingest.
•  Pre-built sinks for
HDFS, HBase, etc.
•  Supports
transformation of data
in-flight.
•  General pub-sub
messaging framework.
•  Just a message
transport.
•  Have to use third party
tool to ingest.

30
Flume and Kafka
•  Kafka Source
•  Kafka Channel

31
Sources Interceptors Selectors Channels Sinks
Flume Agent
Short Intro to Flume
Twitter, logs, JMS,
webserver
Mask, re-format,
validate…
DR, critical
Memory, file,
Kafka
HDFS, HBase,
Solr

32
A Brief Discussion of Flume Patterns – Fan-in
•  Flume agent runs on
each of our servers.
•  These agents send
data to multiple agents
to provide reliability.
•  Flume provides support
for load balancing.

33
Ingestion Decisions
•  Historical Data
–  File transfer
•  Incoming Data
–  Flume with the spooling directory source.
•  Relational Data Sources – ODS, CRM, etc.
–  Sqoop

34
Architectural
Considerations
Data Processing – Engines

35
Processing Engines
•  MapReduce
•  Abstractions – Pig, Hive, Cascading, Crunch
•  Spark
•  Impala
Confidentiality Information Goes Here

36
MapReduce
•  Oldie but goody
•  Restrictive Framework / Innovated Work Around
•  Extreme Batch

37
MapReduce Basic High Level
Mapper
HDFS
(Replicated)
Native File System
Block of
Data
Temp Spill
Data
Partitioned
Sorted Data
Reducer
Reducer
Local Copy
Output File

38
Abstractions
•  SQL
–  Hive
•  Script/Code
–  Pig: Pig Latin
–  Crunch: Java/Scala
–  Cascading: Java/Scala

39
Spark
•  The New Kid that isn’t that New Anymore
•  Easily 10x less code
•  Extremely Easy and Powerful API
•  Very good for machine learning
•  Scala, Java, and Python
•  RDDs
•  DAG Engine

40
Impala
• Real-time open source MPP style engine for Hadoop
• Doesn’t build on MapReduce
• Written in C++, uses LLVM for run-time code generation
• Can create tables over HDFS or HBase data
• Accesses Hive metastore for metadata
• Access available via JDBC/ODBC

41
Architectural
Considerations
Data Processing – What processing needs to
happen?

42
What processing needs to happen?
•  Sessionization
•  Filtering
•  Deduplication
•  BI / Discovery

43
Sessionization
Website visit
Visitor 1
Session 1
Visitor 1
Session 2
Visitor 2
Session 1
> 30 minutes

44
Why sessionize?
Helps answers questions like:
•  What is my website’s bounce rate?
–  i.e. how many % of visitors don’t go past the landing page?
•  Which marketing channels (e.g. organic search, display ad, etc.) are
leading to most sessions?
–  Which ones of those lead to most conversions (e.g. people buying things,
signing up, etc.)
•  Do attribution analysis – which channels are responsible for most
conversions?

45
How to Sessionize?
1.  Given a list of clicks, determine which clicks
came from the same user
2.  Given a particular user's clicks, determine if a
given click is a part of a new session or a
continuation of the previous session

46
#1 – Which clicks are from same user?
•  We can use:
–  IP address (244.157.45.12)
–  Cookies (A9A3BECE0563982D)
–  IP address (244.157.45.12)and user agent string ((KHTML, like
Gecko) Chrome/36.0.1944.0 Safari/537.36")

47
•  We can use:
–  IP address (244.157.45.12)
–  Cookies (A9A3BECE0563982D)
–  IP address (244.157.45.12)and user agent string ((KHTML, like
Gecko) Chrome/36.0.1944.0 Safari/537.36")

48
244.157.45.12 - - [17/Oct/2014:21:08:30 ] "GET /seatposts HTTP/1.0" 200 4463 "http://
bestcyclingreviews.com/top_online_shops" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9_2)
AppleWebKit/537.36 (KHTML, like Gecko) Chrome/36.0.1944.0 Safari/537.36”
244.157.45.12 - - [17/Oct/2014:21:59:59 ] "GET /Store/cart.jsp?productID=1023 HTTP/1.0"
200 3757 "http://www.casualcyclist.com" "Mozilla/5.0 (Linux; U; Android 2.3.5; en-us; HTC
Vision Build/GRI40) AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1”

49
#2 – Which clicks part of the same session?
> 30 mins apart = different
sessions

50©2014 Cloudera, Inc. All rights reserved.
Sessionization engine recommendation
•  We have sessionization code in MR, Spark on github. The
complexity of the code varies, depends on the expertise in the
organization.
•  We choose MR, since it’s fairly simple and maintainable code.

51
Filtering – filter out incomplete records
200 3757 "http://www.casualcyclist.com" "Mozilla/5.0 (Linux; U…

52
Filtering – filter out records from bots/spiders
Google spider IP address

Filtering recommendation
•  Bot/Spider filtering can be done easily in any of the engines
•  Incomplete records are harder to filter in schema systems like
Hive, Impala, Pig, etc.
•  Pretty close choice between MR, Hive and Spark
•  Can be done in Flume interceptors as well
•  We can simply embed this in our sessionization job

54
Deduplication – remove duplicate records

Deduplication recommendation
•  Can be done in all engines.
•  We already have a Hive table with all the columns, a simple
DISTINCT query will perform deduplication
•  We use Pig

BI/Discovery engine recommendation
•  Main requirements for this are:
–  Low latency
–  SQL interface (e.g. JDBC/ODBC)
–  Users don’t know how to code
•  We chose Impala
–  It’s a SQL engine
–  Much faster than other engines
–  Provides standard JDBC/ODBC interfaces

57
Architectural
Considerations
Orchestration

•  Workflow is fairly simple
•  Need to trigger workflow based on data
•  Be able to recover from errors
•  Perhaps notify on the status
•  And collect metrics for reporting
Choosing…
Easier in Oozie

•  Workflow is fairly simple
•  Need to trigger workflow based on data
•  Be able to recover from errors
•  Perhaps notify on the status
•  And collect metrics for reporting
Choosing the right Orchestration Tool
Better in Azkaban

•  The best orchestration tool
is the one you are an expert on
– Oozie
– Spark Streaming, etc. don’t require orchestration
tool
Important Decision Consideration!

61
Putting It All
Together
Final Architecture

Final architecture
Hadoop
Cluster
BI/Visualization
tool (e.g.
microstrategy)
BI
Analysts
Spark For machine learning
and graph processing
R/Python Statistical Analysis
Custom
Apps
3. Accessing
2. Processing
4. Orchestration
1. Ingestion
Operational
Data Store
CRM System
Via Sqoop
Web servers
Website
users
Web logsVia Flume

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Application Architectures with Hadoop

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