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Java without Java
Casey Durfee
[email protected]
CODI 2006
Why should I care?
• You want to get things done
• …or you just want more time to goof off
• You know Horizon will never perfectly
meet your library’s needs
• You don’t have $$$ for custom work
• You want to understand why software isn’t
perfect
• You want the bragging rights of having
seen the geekiest presentation at CODI.
But I can’t…
• Don’t sell yourself short!
Plenty of other people will
be happy to do it for you
• Don’t worry about what
you’re “supposed” to be
able to do
Lack of Social Skills a Plus!
• Be lazy and easily annoyed; take it personally
– Lazy: always look for an easier way
– Easily annoyed: If something doesn’t work right, don’t
just learn to ignore it!
– Take it personally: If you don’t fix it, nobody will
– Don’t take any guff: It’s just a computer. Don’t forget
who’s boss
• Laziness, impatience, hubris (the 3 Perl virtues)
What’s an API?
• Tools to interface with someone else’s
software
• Examples
– Flickr, Google, Amazon, etc.
• Horizon APIs will make it easier to extend
Horizon without knowing too much about
how it works behind the scenes
Foundations
Foundations
Intro to Java
• The Platform (great)
– OS independent
– Fast
– Powerful
• 3rd party support (good)
– Lots of stuff you can use
– Isn’t going anywhere
Intro to Java (continued)
• The language (ehh…)
– Wordy
– Fussy
– Complex
– Steep learning curve
– Good for engineers
• The programmers ($$$)
The Virtual Machine
The Virtual Machine, II
• Java is translated into platform-independent
instructions for a Virtual Machine first
public class helloWorld extends java.lang.Object{
public helloWorld();
Code:
0:
aload_0
1:
invokespecial
#1; //Method java/lang/Object."<init>":()V
4:
return
public static void main(java.lang.String[]);
Code:
0:
getstatic
#2; //Field java/lang/System.out:Ljava/io/PrintStream;
3:
ldc
#3; //String Good morning
5:
invokevirtual
#4; //Method java/io/PrintStream.println:(Ljava/lang/Str
ing;)V
8:
return
}
• Write Once, Run Anywhere (OS independent)
What that Means
• Java is a platform
• Java is a language
• You can use the platform without the
language
• You can program in Java without
programming in Java
Java Example
• Say good morning
public class goodMorning {
public static void main( String[] args ) {
System.out.println(“Good morning”);
}
}
• Ugh… why can’t I just do
print “Good morning”
Java example II
import javax.mail.*;
import javax.mail.internet.*;
import java.util.Properties;
public class sendEmail {
public static void emailSender() {
Properties properties = System.getProperties();
properties.put("mail.smtp.host", "mail1.spl.org");
Session session = Session.getInstance( properties, null );
InternetAddress toAddress = null;
Address fromAddress = null;
try {
toAddress = new InternetAddress( "[email protected]", "Casey Durfee" );
fromAddress = new InternetAddress("[email protected]", "SPL TEST");
} catch (Exception e ) {
e.printStackTrace();
System.exit(1);
}
try {
MimeMessage mimeMessageOn = new MimeMessage(session);
mimeMessageOn.setFrom(fromAddress);
mimeMessageOn.setSubject( "Java test" );
mimeMessageOn.setText( "Isn't java fun?" );
mimeMessageOn.addRecipient(Message.RecipientType.TO, toAddress);
Transport.send( mimeMessageOn );
} catch( Exception e ) {
e.printStackTrace();
}
}
public static void main(String[] args ){
emailSender();
}
}
There’s got to be an easier way
• Java: 38 lines, 894 characters!
– Hard to remember all that stuff
– Still easier than serials prediction patterns
• Sending an email is not rocket science!
(See: your spam folder)
• This should take 4 lines, tops.
–
–
–
–
Tell it we wanna send an email
Get a connection to the email server
Send the email
Close the connection to the server
An Easier Way
• Sending an email in 4 lines…
import smtplib
server = smtplib.SMTP('mail1.spl.org')
server.sendmail( "[email protected]", ["[email protected]"], "From: [email protected]\r\nTo:
[email protected]\r\n\r\nSubject:Isn't java not fun?")
server.close()
• That may seem like gibberish but at least
there’s less of it
Python and Ruby
• Versatile, easy to use languages
• Come with great tools for building
websites (Ruby on Rails, Django)
• Popular with the kids
• Simple and compact
• Will be around for a while
Snakes (and Rubies)
on a JVM!!!!
Jython and JRuby
• Generate java bytecode without you
programming in Java
• Java virtual machine doesn’t know or care
that you didn’t write it in Java
• Can use Java libraries and tools without
writing any Java
• Much easier to learn and use than Java
Other JVM languages
•
•
•
•
Groovy (complex, weird)
Rhino (javascript)
NetRexx ( Rexx )
Nice (Slightly less annoying version of
Java)
• Quercus (PHP, closed source, can't use
java within PHP)
• ColdFusion MX
Which should I choose?
•
•
•
•
•
•
Pick between Python and Ruby first
Neither one is a bad choice
Neither one will cost you a dime
I like them both
…but I’m more productive with Python
...and Python's a lot simpler (less to
remember)
Quick Jython Example 1
• Let's make a graphical user interface:
# jython
from java.lang import *
from javax.swing import
window = JFrame("jython
button = JButton("hello
window.contentPane.add(
window.pack()
window.show()
*
demo")
world")
button )
#jruby
require 'java'
include_class ['javax.swing.JFrame', 'javax.swing.JButton']
window = JFrame.new "JRuby Demo"
button = JButton.new "hello world"
window.contentPane.add button
window.pack
window.show
Reading a MARC record (using marc4j)
jython
>>> from org.marc4j import *
>>> from java.io import *
>>> inStream =
FileInputStream("spl.marc")
>>> marcReader = MarcStreamReader(
inStream )
>>> marcRecord = marcReader.next()
>>> print marcRecord
LEADER 01265nam 2200337 a 4500
001 ocm62127695
003 OCoLC
005 20060817030408.0
008 050921s2006
nyu
c
000 1
eng
010
$a 2005027306
020
$a0316057533 (trade pbk.)
024 3 $a9780316057530
040
$aDLC$cDLC$dBAKER$dUOK
042
$alcac
...
jruby
require 'java'
include_class ['org.marc4j.MarcStreamReader',
'java.io.FileInputStream']
inStream = FileInputStream.new "spl.marc"
marcReader = MarcStreamReader.new inStream
marcRecord = marcReader.next
p marcRecord
LEADER 01265nam 2200337 a 4500
001 ocm62127695
003 OCoLC
005 20060817030408.0
008 050921s2006
nyu
c
000 1 eng
010
$a 2005027306
020
$a0316057533 (trade pbk.)
024 3 $a9780316057530
040
$aDLC$cDLC$dBAKER$dUOK
042
$alcac
...
Z39.50 query w/Jython (using
Jafer)
Does a Z39.50 query and print out results as XML.
from org.jafer.zclient import *
from org.jafer.util.xml import DOMFactory, XMLSerializer
from org.jafer.query import *
from java.lang import *
from java.io import StringWriter
z = ZClient()
z.setHost("z3950.loc.gov")
z.setPort(7090)
query = QueryBuilder()
numHits = z.submitQuery( query.getNode("author", "Durfee"))
z.setRecordCursor(1)
sw = StringWriter()
XMLSerializer.out( z.getCurrentRecord().getXML(), "xml", sw )
z.close()
print sw
Z39.50 Query results
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<mods xmlns="http://www.loc.gov/mods/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.loc.gov/mods/ http://www.loc.gov/standards/mods/mods.xsd">
<title>Analytic philosophy and phenomenology /</title>
<name type="personal">Durfee, Harold A.1920-</name>
<typeOfResource>text</typeOfResource>
<genre>
<controlledValue>bibliography</controlledValue>
</genre>
<publication>
<placeOfPublicationCode authority="marc">ne </placeOfPublicationCode>
<placeOfPublication>The Hague :</placeOfPublication>
<publisher>Nijhoff,</publisher>
<issuance>monographic</issuance>
</publication>
<date type="issued">1976.</date>
<language authority="iso 639-2b">eng</language>
<formAndPhysicalDescription>
<extent>viii, 277 p. ;24 cm.</extent>
</formAndPhysicalDescription>
<note>Includes index.</note>
...
Less Quick Jython Example
• Let’s create a report of circulation statistics
and email it out as an Excel spreadsheet
• We’ll use a couple of java tools to make
our lives easier
– Spring (http://www.springframework.org/ ) for
database connection
– POI (http://jakarta.apache.org/poi/ ) to
generate spreadsheet
– SPL-developed convenience functions
• Same # of lines as Java email program
from spl.Horizon import DBWrapper
from spl.misc import poi
from spl.email import easyEmailSender
import time
conn = DBWrapper.DBWrapperFromProperties("horizon")
checkoutsAndRenewalsQuery = """select sum(total) from stat_summary
where location in ( '%(location)s' ) and stat_category
= 'cko'
and year = %(year)d and month = %(month)d and day =
%(day)d"""
checkinsQuery = """select sum(total) from stat_summary
where location in ('%(location)s') and stat_category = 'cki'
and year = %(year)d and month = %(month)d and day = %(day)d"""
newBorrQuery = """select sum(total) from stat_summary
where location in ('%(location)s') and stat_category = 'bordel'
and year = %(year)d and month = %(month)d and day = %(day)d
and stat_subcategory in ( '1', '3')"""
LOCATIONS_TO_RUN_FOR = [ 'bea', 'bal', 'cen']
results = [ [ "Date", "Location", "Checkouts and Renewals", "Checkins", "New
Borrowers"] ]
date = time.strftime("%m-%d-%Y")
month,day,year = date.split("-")
for locationOn in LOCATIONS_TO_RUN_FOR:
params = { 'location' : locationOn, 'year' : year, 'month' : month, 'day' : day }
numCheckouts = conn.queryForInt( checkoutsAndRenewalsQuery % params )
numCheckins = conn.queryForInt( checkinsQuery % params )
numNewBorrowers = conn.queryForInt( newBorrQuery % params )
results.append( [ date, locationOn, numCheckouts, numCheckins, numNewBorrowers] )
fileName = "spl-circ-stats-%s.xls" % date
poi.writeSpreadsheet( fileName , results )
sender = easyEmailSender.easyEmailSender("[email protected]", "Casey Durfee", "circ
stats for %s" % date, "see attached spreadsheet" )
sender.setFileName( fileName, "statistics spreadsheet")
sender.sendMessage()
Where do I go from here?
• Learn Python or Ruby first
– Even if you never use Jython/JRuby, it will be
worth your time
• Learn a little bit about Java
– If only so you will know how good you have it
• Don’t wait for the 8.0 APIs to be released
“At my local Barnes and Noble, there is a
huge wall of Java books just waiting to tip
over and crush me one day. And one day it
will. At the rate things are going, one day
that bookcase will be tall enough to crush
us all. It might even loop the world several
times, crushing previous editions of the
same Java books over and over again.”
--Why, Why’s (poignant) Guide to Ruby
Getting Started with Python
• How to Think like a Computer Scientist
Using Python (beginning) :
http://www.ibiblio.org/obp/thinkCSpy/
• Dive Into Python (advanced)
http://www.diveintopython.org/
• Learning Python (ISBN 0596002815 )
• Jython Essentials ( ISBN 0596002475 )
• http://www.jython.org
Getting Started With Ruby
• Programming Ruby: The Pragmatic
Programmers’ Guide : online at
http://www.rubycentral.com/book/ (ISBN
0974514055 )
• Why’s (poignant) guide to Ruby :
http://poignantguide.net/ruby/
• http://www.jruby.org
Useful Java APIs
• Jafer (Z39.50): http://www.jafer.org
• Marc4j (MARC reader):
http://marc4j.tigris.org
• POI (create MS Word/Excel files):
http://jakarta.apache.org/poi