Re: Connecting to LDAP Directory with EOModeler

2006-05-17 Thread Chuck Hill


On May 15, 2006, at 5:50 PM, Xia, Wen wrote:

I need to get some data from an LDAP directory.  I tried to use the  
JNDI adaptor to create an EOModel for this data.  I was successful  
in creating the model and browsing the data in EOModeler, but I was  
unable to use the model in any code to actually do anything  
useful.  I kept getting error:


WorkerThread5 java.lang.NullPointerException
at com.sun.jndi.ldap.LdapNamingEnumeration.getNextBatch 
(LdapNamingEnumeration.java:110)
at com.sun.jndi.ldap.LdapNamingEnumeration.nextAux 
(LdapNamingEnumeration.java:244)
at com.sun.jndi.ldap.LdapNamingEnumeration.nextImpl 
(LdapNamingEnumeration.java:235)


I searched through the apple mailing list and its archive.  I found  
some posts with the same problem, but I did not see a solution to it.


Looks like a modelling error.  LDAP models can be a bear to get right.

Also see
http://lists.apple.com/archives/Webobjects-dev/2005/Sep/msg00638.html
http://lists.apple.com/archives/Webobjects-dev/2005/Sep/msg00588.html

From the 5.1 Release Notes:
Reference   2753067
Problem 	The JNDI adaptor (with the LDAPPlugIn) sometimes throws a  
NullPointerException when fetching from a Netscape Directory Server.
Description	The problem has been observed on a Netscape Directory  
Server while searching an object class that has a large number of  
entries (on the order of thousands).There seems to be a problem with  
the LDAP Service Provider that Sun distributes. The  
LdapNamingEnumeration implementation of next() throws a  
NullPointerException in violation of the JNDI specification.The  
exception message follows:Exception in thread main  
java.lang.NullPointerException at  
com.sun.jndi.ldap.LdapNamingEnumeration.getNextBatch 
(LdapNamingEnumeration.java:107) at  
com.sun.jndi.ldap.LdapNamingEnumeration.nextAux 
(LdapNamingEnumeration.java:180) at  
com.sun.jndi.ldap.LdapNamingEnumeration.next 
(LdapNamingEnumeration.java:171) ... etc.


Workaround  Catch the exception and/or repeat the attempt to fetch.  
The problem seems to occur frequently but somewhat irregularly.




From the limited documentation I could find, it looks like a JNDI  
model should work just like a JDBC model.  Is anyone successfully  
using the JNDI adaptor to fetch LDAP data using EOModel?  If so,  
what is the trick in getting it to work?




If all else fails,
Another alternative to using an EOModel to interact with an LDAP  
type store is to use Novell's Directory Services code. The Novel  
code is open sourced and provides all of the features and  
functionality to read and write to
X.500 stores. It even supports SSL, Kerberos, and some other  
authentication services. The Novell code can be found at http:// 
developer.novell.com/ndk/jldap.htm


It says Netware and Windows but it runs just fine on OSX, and Linux.

-- Dov Rosenberg


Chuck

--
Coming in 2006 - an introduction to web applications using WebObjects  
and Xcode http://www.global-village.net/wointro


Practical WebObjects - for developers who want to increase their  
overall knowledge of WebObjects or who are trying to solve specific  
problems.http://www.global-village.net/products/practical_webobjects





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Connecting to LDAP Directory with EOModeler

2006-05-15 Thread Xia, Wen
Title: Connecting to LDAP Directory with EOModeler



I need to get some data from an LDAP directory. I tried to use the JNDI adaptor to create an EOModel for this data. I was successful in creating the model and browsing the data in EOModeler, but I was unable to use the model in any code to actually do anything useful. I kept getting error:

WorkerThread5 java.lang.NullPointerException
at com.sun.jndi.ldap.LdapNamingEnumeration.getNextBatch(LdapNamingEnumeration.java:110)
at com.sun.jndi.ldap.LdapNamingEnumeration.nextAux(LdapNamingEnumeration.java:244)
at com.sun.jndi.ldap.LdapNamingEnumeration.nextImpl(LdapNamingEnumeration.java:235)

I searched through the apple mailing list and its archive. I found some posts with the same problem, but I did not see a solution to it. From the limited documentation I could find, it looks like a JNDI model should work just like a JDBC model. Is anyone successfully using the JNDI adaptor to fetch LDAP data using EOModel? If so, what is the trick in getting it to work? 

Thank you.





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