Download Greetings from the Edge: Using javaobj in DATA Step

Greetings from the Edge:
Using javaobj in DATA Step
Richard A. DeVenezia
Independent Consultant
SAS is a registered trademark or trademark of SAS Institute Inc. in the USA and other countries. ® indicates USA registration.
Other brand and product names are registered trademarks or Trademarks of their respective companies.
Slide imagery copyright © 2004, SAS Institute Inc.
Copyright © 2004 , Richard A. DeVenezia. All rights reserved.
Overview

SAS Version 9 DATA Step
has experimental syntax for
interfacing with objects
• Java, Hash, HashIter

Demonstration by way of
examples.
Copyright © 2004 , Richard A. DeVenezia. All rights reserved.
Java is ...

java.sun.com
“The Java 2 Platform provides robust end-to-end solutions for
networked applications as well as a trusted standard for embedded
applications”

Widespread

Networked

Applications
• Analysis and management
Copyright © 2004 , Richard A. DeVenezia. All rights reserved.
Component Interface is ...

support.sas.com/rnd/...
“DATA Step Component Interface provides a mechanism for
accessing predefined component objects from within a DATA Step
program.”

Instantiate
• Create an object
• declare Type var, var = _new_

Access
• var.method()
Copyright © 2004 , Richard A. DeVenezia. All rights reserved.
javaobj is ...

DATA Step

Experimental

Part of broader initiative
• Component Interface
• Object Dot Syntax
Copyright © 2004 , Richard A. DeVenezia. All rights reserved.
Java development

Free kit
•java.sun.com/j2se
• compiler, packager and loader
javac, jar, java
• Runtime Environment
• Online training

Tutorials
• numerous web sites and publications
Copyright © 2004 , Richard A. DeVenezia. All rights reserved.
The edge

New or experimental

Where two things come together
Copyright © 2004 , Richard A. DeVenezia. All rights reserved.
SAS session

Version 9
• CLASSPATH environment variable
-set CLASSPATH myPath;%CLASSPATH%

Version 9.1
• jreoptions SAS option
-jreoptions (
-Djava.class.path=myPath;%CLASSPATH%
-Dsas.jre.version=jrePath
)
Default JRE is installed at shared\JRE\1.4.1
Copyright © 2004 , Richard A. DeVenezia. All rights reserved.
A little birdie

Version 9.1
Proc JAVAINFO

--log-java.version = 1.4.1
java.vm.version = 1.4.1-b21
java.home = c:\opt\sas\shared\JRE\1.4.1
java.class.path = <no value>
...
Copyright © 2004 , Richard A. DeVenezia. All rights reserved.
Java coding pattern - variables
public class Class
{
private double variable;
public double getVariable()
{
return this.variable;
}
public void setVariable(double variable)
{
this.variable = variable;
}
}

java.sun.com/docs/codeconv
/html/CodeConvTOC.doc.html
Copyright © 2004 , Richard A. DeVenezia. All rights reserved.
Java coding pattern - methods
public class Class
{
public <class> methodNameAsVerb(args...)
{...}
}

java.sun.com/docs/codeconv
/html/CodeConvTOC.doc.html
Copyright © 2004 , Richard A. DeVenezia. All rights reserved.
Declare statement

declare javaobj var
('Class' [,arg-1[,…[,arg-N]]) ;
- or 


declare javaobj var;
var = _NEW_ javaobj
('Class' [,arg-1[,…[,arg-N]]) ;
declare javaobj j (‘java/lang/String’);
declare javaobj j
(‘java/awt/geom/Ellipse2D/Double’);
Copyright © 2004 , Richard A. DeVenezia. All rights reserved.
Accessing methods and fields

public Type method (args…) {…}

obj.callTypeMethod ( ‘method’, args…, return );

public Type field;

obj.[get|set]TypeField ( ‘field’, value );
Copyright © 2004 , Richard A. DeVenezia. All rights reserved.
HelloSAS.java
public class HelloSAS
{
public String getMessage ()
{
return "Hello SAS";
}
}
Copyright © 2004 , Richard A. DeVenezia. All rights reserved.
HelloSAS.sas
data _null_;
length message $200;
declare javaobj j (’HelloSAS');
j.callStringMethod ('getMessage', message);
put message=;
run;
--- log -message=Hello SAS
Copyright © 2004 , Richard A. DeVenezia. All rights reserved.
Gotchas

Classes are cached per SAS session

Did you recompile a Java class?
• Restart SAS

Signature Types
• pass double, String, javaobj
• return double, String
Copyright © 2004 , Richard A. DeVenezia. All rights reserved.
SystemProperties.class
import java.util.Enumeration;
public class SystemProperties {
private Enumeration e;
public SystemProperties () {
e = System.getProperties().propertyNames();
}
public String getProperty () {
if (e.hasMoreElements()) {
String p = (String) e.nextElement();
return p + "=" + System.getProperty(p);
}
else {
return null;
}
}
}
Copyright © 2004 , Richard A. DeVenezia. All rights reserved.
SystemProperties.sas
data _null_;
dcl javaobj j (’SystemProperties');
length s $200;
j.callStringMethod ('getProperty', s);
do while (s ne '');
put s;
j.callStringMethod ('getProperty', s);
end;
run;
--- log --...
java.vm.version=1.4.2_03-b02
java.vm.vendor=Sun Microsystems Inc.
sas.jre.home=C:\j2sdk1.4.2_03\jre
…
Copyright © 2004 , Richard A. DeVenezia. All rights reserved.
Exceptions


Always check, handle and clear
exceptionDescribe(1)
•write exceptions to stdout or console

exceptionCheck(rc)
•did an exception occur ?

exceptionClear()
•clear the exception flag
Copyright © 2004 , Richard A. DeVenezia. All rights reserved.
Object persistence

Intra DATA Step ? No
• javaobj is gone when DATA Step ends
• obj.delete() recommended

Birdie:
“An instantiated javaobj creates a JNI reference which will
not be garbage collected. The reference needs to be
explicitly deleted.”
Copyright © 2004 , Richard A. DeVenezia. All rights reserved.
Case for persistence

Creating SAS Table from Q, a DBMS Query

Q  java.sql.ResultSet
• Two SAS Passes
• 1. ResultSetMetaData, columns and types
• 2. ResultsSet, rows

Without persistence, Q must be issued for each
pass
• not wanted
Copyright © 2004 , Richard A. DeVenezia. All rights reserved.
Persistence categories

Intra SAS session
• Object persists between DATA Steps in one SAS session
• static fields and thread

Inter SAS session
• Object persists between DATA Steps and SAS sessions
• Remote method invocation - RMI

Require wrapper classes
Copyright © 2004 , Richard A. DeVenezia. All rights reserved.
Persistence via Static

Static fields

java
public class Persist {static double x,y,z; }

sas
data _null_; declare javaobj j ('Persist');
j.setStaticDoubleField('x',100); j.delete();
run;
data _null_; declare javaobj j ('Persist');
j.getStaticDoubleField('x',x); j.delete();
put x=;
run;
x=100
Copyright © 2004 , Richard A. DeVenezia. All rights reserved.
Persistence via Thread

Runnable (R)
• monitors its state
• persists in Thread started by A

Adapter (A)
• new Thread ( new R() ) . start ()
• methods grant access to R’s state
• static fields persist across DATA Step
-reference to R
Copyright © 2004 , Richard A. DeVenezia. All rights reserved.
Persistence via RMI

Server process outside of SAS

DATA Step is client of server
• via wrapper

Server allocates resources
• Returns handles
• Methods accessed by handle
Copyright © 2004 , Richard A. DeVenezia. All rights reserved.
DBMS servers

Commercial

Open source
• Postgresql
• mySQL

JDBC
• not an acronym (just like ess-a-ess)
• trademark
• 210 drivers listed at
http://servlet.java.sun.com/products/jdbc/drivers
Copyright © 2004 , Richard A. DeVenezia. All rights reserved.
JDBC connection pattern
Class.forName(jdbcDriver);
Connection con = DriverManager.getConnection
( URL, username, password );

jdbcDriver = “org.postgresql.Driver”

URL =
“jdbc:postgresql://www.devenezia.com:5434/sesug03demo”

username = “sesug03demo”

password = “D3m0oeoe”
Copyright © 2004 , Richard A. DeVenezia. All rights reserved.
Gateway - an RMI scheme

Three classes

An Interface
• GatewayInterface

An Implementation
• GatewayManager

A Server
• GatewayServer
Copyright © 2004 , Richard A. DeVenezia. All rights reserved.
GatewayInterface

Declares methods
public int getConnectionHandle (
String driverClass, String databaseURL,
String username, String password )
throws RemoteException;
public int getStatementHandle (int cHandle) throws
RemoteException;
public int executeQuery (int handle, String sql) throws
RemoteException;
Copyright © 2004 , Richard A. DeVenezia. All rights reserved.
GatewayManager

Implements the Interface
public int getConnectionHandle (
String driverClass, String databaseURL,
String username, String password)
throws RemoteException
{
…
try
{
System.out.println ("loading "+driverClass);
Class.forName(driverClass);
System.out.println ("connecting to "+databaseURL);
con = DriverManager.getConnection
(databaseURL, username, password);
System.out.println ("connected");
}
…
Copyright © 2004 , Richard A. DeVenezia. All rights reserved.
GatewayServer

Hosts a GatewayManager
protected static final String
RMI_NAME = "JDBC-GATEWAY-MANAGER";
public static void main(String args[]){
…
try {
LocateRegistry.createRegistry(1099);
GatewayManager manager = new GatewayManager (5);
Naming.rebind (RMI_NAME, manager);
}
…
System.out.println ( manager.getClass().getName()
+ " ready to manage " + 5 + " connections.");
Copyright © 2004 , Richard A. DeVenezia. All rights reserved.
DataStepGatewayAdapter

Reimplements GatewayInterface
• creates and uses delegate
• performs typecasting where needed
public class DataStepGatewayAdapter
{ private GatewayInterface dbi;
public DataStepGatewayAdapter() throws Exception {
dbi=GatewayServer.getReferenceToPersistentManager ();
}
public int getStatementHandle (double cHandle) throws
Exception
{ return dbi.getStatementHandle ( (int) cHandle); }
Copyright © 2004 , Richard A. DeVenezia. All rights reserved.
SAS macros

Facilitate use of Gateway

startServer

getConnectionHandle

getStatementHandle

jdbcLoadTable

jdbcQuery
Copyright © 2004 , Richard A. DeVenezia. All rights reserved.
Using the macros

Reimplements GatewayInterface
%let jdbc_server_policy = gateway.policy;
%let jdbc_driver = org.postgresql.Driver;
%let db_url =
jdbc:postgresql://www.devenezia.com:5434/sesug03demo;
%let username = sesug03demo ;
%let password = D3m0oeoe;
%let cHandle =;
%getConnectionHandle ( driver = &jdbc_driver , url =
&db_url , user = &username , pass = &password ,
cHandle_mv = cHandle );
Copyright © 2004 , Richard A. DeVenezia. All rights reserved.
Using the macros
%jdbcLoadTable (
cHandle=&cHandle,
data=sashelp.zipcode,
obs=20);
%jdbcQuery (
cHandle=&cHandle,
sql=SELECT * FROM ZIPCODE, out=WORK.ZIPCODE);
Copyright © 2004 , Richard A. DeVenezia. All rights reserved.
Other tasks handled well by Java

Directory listings

Archived file sets

Database connectivity

2D and 3D graphics

Open Office

XML

HTML parsing

and so much more
Copyright © 2004 , Richard A. DeVenezia. All rights reserved.
Conclusion

Javaobj opens new horizons
• Utilize problem solvers who work in Java

Hybrid solutions
• Combine features of different technologies

Paper, slides and examples
www.devenezia.com/papers
Copyright © 2004 , Richard A. DeVenezia. All rights reserved.