NiFi for Clickstream Log Ingestion into HBase + Phoenix for BI Dashboard

[#1]

Synopsis

• You are a marketing analyst tasked with developing a BI dashboard for management that reports on website activity in realtime throughout the day for Black Friday, the day after Thanksgiving.
• Unfortunately, all of the data engineers are busy with other projects and cannot immediately help you.
• Not to worry. With Hortonworks DataFlow, powered by Apache NiFi, you can easily create a data flow in minutes to process the data needed for the dashboard.

Source Data:

• Fictitious online retailer Initech Corporation
• JSON Formatted Clickstream data
• Your company stores the raw Clickstream log files in HDFS. The JSON formatted log files are written to HDFS directories partitioned by day and hour. For example:
  • /data/clickstream/2016-11-20/hour=00
  • /data/clickstream/2016-11-20/hour=01
  • /data/clickstream/2016-11-20/hour=...
  • /data/clickstream/2016-11-20/hour=23
• There could also be subdirectories under the hour
• This directory structure or a similar variant is commonly found in organizations when storing Clickstream logs
• The JSON data contains nested hierarchies. Sample JSON record:

Solution considerations:

• New files are written throughout the day for each hour and late arriving data is added to existing hours.
• Since files are constantly arriving, you need the data flow to always be on and running
• HBase is a fast and scalable option for the backend datastore:
  • Data is semi-structured JSON
  • HBase does not require a Schema
  • HBase was designed for high throughput writes, whereas Hive is better suited for batch loads
• Use Apache Phoenix to create a view atop the HBase table:
  • Phoenix creates the schema for reporting
  • Phoenix lets you write ANSI SQL queries against the HBase data
  • Phoenix JDBC driver allows any BI tool to connect

HDF DataFlow Overview:

* You may need to increase the heap size used by NiFi. You will know if/when you start getting the error: java.lang.OutOfMemoryError

Throughput:

• HDF loaded 215,699 records into HBase in under 33 seconds
• I'm running HDF on a single node with 64 GB Ram and 16 cores
• There are other Hadoop and Hadoop related services running on this node including Node Manager, DataNode, Livy Server, RegionServer, Phoenix Query Server, NFSGateway, Metrics Monitor

Step 1:

Create the HBase table. You can easily do this via Apache Zeppelin.

• Create 1 column family 'pageview'
• Multiple versions are not needed as there are no updates to this data. Each website hit is unique.

Step 2:

Create the Phoenix view. You can easily do this via Apache Zeppelin.

Step 3:

Configure the ListHDFS processor

• The ListHDFS processor will only list new files as they are written to directories
• The DataFlow will be constantly running so we do not want to process the same data twice. Thus, the ListHDFS processor will prevent us from processing the same data twice
• Our top-level directory is the Clickstream data for 2016-11-20
• ListHDFS will list all new files beneath the subdirectories under the top-level directory of 2016-11-20
• Notice that the value for 'Directory' is the top-level directory '/data/clickstream/2016-11-20'
• The value for 'Recursive Subdirectories' is set to 'true' so that all new files will be picked up as they are added
• The Hadoop Configuration Resources are the full path locations to core-site.xml and hdfs-site.xml

Step 4:

Configure the FetchHDFS processor

• The ListHDFS processor will list files
• FetchHDFS will retrieve the contents from the files listed

Step 5:

Use the SplitText processor to split each JSON record from the HDFS files

I used the processor as is without any changes, other than renaming it to 'Split_Lines_In_File'

Step 6:

Configure the JoltTransformJSON processor to extract only those fields needed for the dashboard.

We only need the following fields from the JSON data:

1. event ID - unique identifier for each website hit
2. event time - time when the website hit occurred
3. url - url of the page viewed
4. country - country that the page was served
5. session id - session id for the user
6. user cookie
7. os - the users device os
8. browser - browser that the user used

Some of the above fields are child elements for a top-level parent. The property 'Jolt Specification' needs to be set so that we properly extract those fields:

Step 7:

Configure the PutHBaseJSON processor to store the record.

Apache Zeppelin Notebook:

[#2]

awesome @Binu Mathew

[#3]

@Binu Mathew : Thanks for sharing the awesome article. Do you mind to share the sample data?