Build and Install Nutch 2.2 with MySQL

This tutorial will teach you to build set up Apache Nutch (latest version -2.2) with MySql. Let's get started !

Install MySQL Server and MySQL Client using the Ubuntu software center or  sudo apt-get install mysql-server mysql-client  at the command line.

As MySQL defaults to latin we need to edit  sudo vi /etc/mysql/my.cnf  and under [mysqld] add

innodb_file_format=barracuda
innodb_file_per_table=true
innodb_large_prefix=true
character­set­server=utf8mb4
collation­server=utf8mb4_unicode_ci
max_allowed_packet=500M

The innodb options are to help deal with the small primary key size restriction of MySQL. The character and collation settings are to handle Unicode correctly.The max_allowed_packet settings is optional and only necessary for very large sizes. Restart your machine for the changes to take effect.

Check to make sure MySQL is running by typing  sudo netstat -tap | grep mysql  and you should see something like:
tcp 0 0 localhost:mysql *:* LISTEN

We need to set up the nutch database manually as the current Nutch/Gora/MySQL generated db schema defaults to latin.
Log into mysql at the command line using your previously set up MySQL id and password type

mysql -u xxxxx -p
then in the MySQL editor type the following:

CREATE DATABASE nutch DEFAULT CHARACTER SET utf8mb4 DEFAULT COLLATE utf8mb4_unicode_ci; 

use nutch;

and enter and then copy and paste the following altogether:

CREATE TABLE `webpage` (
`id` varchar(767) NOT NULL,
`headers` blob,
`text` longtext DEFAULT NULL,
`status` int(11) DEFAULT NULL,
`markers` blob,
`parseStatus` blob,
`modifiedTime` bigint(20) DEFAULT NULL,
`prevModifiedTime` bigint(20) DEFAULT NULL,
`score` float DEFAULT NULL,
`typ` varchar(32) CHARACTER SET latin1 DEFAULT NULL,
`batchId` varchar(32) CHARACTER SET latin1 DEFAULT NULL,
`baseUrl` varchar(767) DEFAULT NULL,
`content` longblob,
`title` varchar(2048) DEFAULT NULL,
`reprUrl` varchar(767) DEFAULT NULL,
`fetchInterval` int(11) DEFAULT NULL,
`prevFetchTime` bigint(20) DEFAULT NULL,
`inlinks` mediumblob,
`prevSignature` blob,
`outlinks` mediumblob,
`fetchTime` bigint(20) DEFAULT NULL,
`retriesSinceFetch` int(11) DEFAULT NULL,
`protocolStatus` blob,
`signature` blob,
`metadata` blob,
PRIMARY KEY (`id`)
) ENGINE=InnoDB
ROW_FORMAT=COMPRESSED
DEFAULT CHARSET=utf8mb4;

Then type enter. You are done setting up the MySQL database for Nutch.

Set up Nutch 2.2 by downloading the apache­nutch­2.2­src.tar.gz version from
http://www.apache.org/dyn/closer.cgi/nutch/.
Untar the contents of the file you just downloaded to a folder we will refer to
going forward as ${APACHE_NUTCH_HOME}.

From inside the nutch folder ensure the MySQL dependency for Nutch is available by editing the following in ${APACHE_NUTCH_HOME}/ivy/ivy.xml
change

<dependency org=”org.apache.gora” name=”gora­core” rev=”0.3′′ conf=”*­>default”/>
to
<dependency org=”org.apache.gora” name=”gora­core” rev=”0.2.1′′ conf=”*­>default”/>

and uncomment the gora­sql

<dependency org=”org.apache.gora” name=”gora­sql” rev=”0.1.1­incubating” conf=”*­>default” />
and uncomment the mysql connector

<!– Uncomment this to use MySQL as database with SQL as Gora store. –>
<dependency org=”mysql” name=”mysql­connector­java” rev=”5.1.18′′ conf=”*­>default”/>

Also update the following jetty mortbay dependency with latest version (7.0.0.pre5),else you might get build failure:

<dependency org="org.mortbay.jetty" name="jetty" rev="7.0.0.pre5" conf="test->default" />
 <dependency org="org.mortbay.jetty" name="jetty-util" rev="7.0.0.pre5" conf="test->default" />

<dependency org="org.mortbay.jetty" name="jetty-client" rev="7.0.0.pre5" />

Edit the ${APACHE_NUTCH_HOME}/conf/gora.properties file either deleting or commenting out the Default SqlStore
Properties using #. Then add the MySQL properties below replacing xxxxx with the user and password you set up when installing MySQL earlier.

###############################
# MySQL properties #
###############################
gora.sqlstore.jdbc.driver=com.mysql.jdbc.Driver
gora.sqlstore.jdbc.url=jdbc:mysql://localhost:3306/nutch?createDatabaseIfNotExist=true
gora.sqlstore.jdbc.user=xxxxx
gora.sqlstore.jdbc.password=xxxxx

Edit the ${APACHE_NUTCH_HOME}/conf/gora­sql­mapping.xml file changing the length of the primarykey from 512 to 767 in both places.
<primarykey column=”id” length=”767′′/>

Configure ${APACHE_NUTCH_HOME}/conf/nutch­site.xml to put in a name in the value field under http.agent.name. It can be anything but cannot be left blank. You must specify Sqlstore.

<property>
<name>http.agent.name</name>
<value>DemoWebCrawler</value>
</property>
<property>
<name>http.accept.language</name>
<value>ja­jp, en­us,en­gb,en;q=0.7,*;q=0.3</value>
<description>Value of the “Accept­Language” request header field.This allows selecting non­English language as default one to retrieve.It is a useful setting for search engines build for certain national group.
</description>
</property>
<property>
<name>parser.character.encoding.default</name>
<value>utf­8</value>
<description>The character encoding to fall back to when no other information
is available</description>
</property>
<property>
<name>storage.data.store.class</name>
<value>org.apache.gora.sql.store.SqlStore</value>
<description>The Gora DataStore class for storing and retrieving data.Currently the following stores are available: ....
</description>
</property>

Install ant using the Ubuntu software center or  sudo apt-get install ant  at the command line.
From the command line  cd  to your nutch folder and  after you have  cd  to ${APACHE_NUTCH_HOME} simply type  ant runtime
This may take a few minutes to compile.

Start your first crawl by typing the lines below at the terminal (replace ‘http://nutch.apache.org/’ with whatever site you want to crawl):

Inject a URL into the DB

cd ${APACHE_NUTCH_HOME}/runtime/local

mkdir -p urls

echo 'http://nutch.apache.org/' > urls/seed.txt

Start crawling (you will want to create your own script later but manually just to see what is happening type the following into the command line:

bin/nutch inject urls
bin/nutch generate -topN 20
bin/nutch fetch -all
bin/nutch parse -all
bin/nutch updatedb

Repeat the last four commands (generate, fetch, parse and updatedb) again.

For the generate command, topN is the max number of links you want to actually parse each time. The first time there is only one URL (the one we injected from seed.txt) but after that there are many more. Note, however, Nutch keeps track of all links it encounters in the webpage table. It just limits the amount it actually parses to TopN so don’t be surprised by seeing many more rows in the webpage table than you expect by limiting with TopN.

Check your crawl results by looking at the webpage table in the nutch database.
mysql -u xxxxx -p
use nutch;
SELECT * FROM nutch.webpage LIMIT 10;

You should see the 10 rows/results of your crawl ( i have shown in mysql workbench):

Now that you have successfully set up Apache nutch with MySql and crawl few web site.Its time to do something more interesting stuff like,using this crawl data for indexing and searching.Follow the next tutorial.