JSP & Native methods - Is JNI best practice?

I have been doing some research before beginning my next project, which needs JSP to interact with a C API. I have only used JSP for 3-4 months, and that was 2 years ago, so I'm not too fluent with it yet. (My company primarily uses PHP.) So far, the options I have come across are:
1) Executing the C program from a Servlet using CLI and parsing the output.
2) JNI function calls (preferable)
However, while researching this subject, I have come across some discussions/threads (not in this forum) that suggested JNI doesn't work well with JSP. Their reasonings included:
-- If anything goes seriously wrong in the C part of your application, it will very likely crash your J2EE server, downing all other web services and applications it is running.
-- Because of the 'reactivatable' nature of web applications means there is no guarantee that a static initializer will not be executed more than once during one JVM run.
-- Problems involving servlets' multi-threaded nature. (http://www.javaquestions.org/ftopic19816.html) I don't think this will be a problem for me, since this is for an intranet, and I believe there should only be one user at a time.
Are any of those points valid? Is JNI the best way to go?
Thanks for any help you can give,
Matt Calderwood

Valid, sure. But you should be able to overcome most of these through coding:
If anything goes seriously wrong in the C part of your application, it will very likely crash your J2EE server, downing all other web services and applications it is running.
Yeah, so test it first. There's 100 other ways your server can (and probably will) go down. What do you do about those?
Because of the 'reactivatable' nature of web applications means there is no guarantee that a static initializer will not be executed more than once during one JVM run.
And how relevant is this to what you're doing? Not terribly, I bet.
Problems involving servlets' multi-threaded nature. (http://www.javaquestions.org/ftopic19816.html) I don't think this will be a problem for me, since this is for an intranet, and I believe there should only be one user at a time.
Can't you resolve this mostly yourself through good threaded code?
I run a website that connects to some ActiveX controls (namely CXServer, which access Omron PLC controllers) through JNI for purposes of retrieving and displaying line status through webpages. I generated the JNI code dynamically using JacoZoom's product. It has been no more troublesome than any other J2EE application. Everytime there's a problem, I can directly attribute it to my level of retardation, or lack of sleep.

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at
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at java.lang.Class.newInstance0(Class.java:355)
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Mark_Galeck wrote:
I am trying to use JNI - I want to have a Java class Foo have a
method, that is a native C function.
I follow the Sun's tutorial
http://java.sun.com/developer/onlineTraining/Programming/JDCBook/jnie...
exactlyNot quite exactly. Yours is an applet, theirs is an application.
Applets are not allowed many things that applications can do.
Among them, loading native libraries.

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Hi,
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Business Objects XI (3.1) - SP3.
Running on Red Hat Enterprise Linux OS.
7,000+ Crystal Reports 2008 *.rpt objects ONLY (No Universe / No WebI).
All reports connecting to Oracle 10g databases.
==================
In the past, all of this infrastructure was running on Windows Server OS and providing the database access via a Named ODBC connection (eg. "APP_DATA".)
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2.) ODBC connection
3.) JDBC connection
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1b.) Oracle Native connection may not be supported on Linux - http://www.forumtopics.com/busobj/viewtopic.php?t=118770&view=previous&sid=9cca754b468fc67888ab2553c0fbe448 [CON]
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==================
We would appreciate some advice from anyone who has been down this road before.
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What can you add to the Pros and Cons listed above?
How do we find the "sweet spot" between quality/performance/speed of reports and easy-overhead for the Admins and Developers?
As always, thanks in advance for your comments.

Hi,
I just saw this article and I would like to add some infos.
First you can quite easely reproduce the same way of working with the odbc entries by playing with the oracle name resolution on the server. By changing some files (sqlnet, tnsnames.ora,..) you can define a different oracle server for a specific name that will be the same accross all environments.
Database name will be resolved differently regarding to the environment and therefore will access a different database.
Second option is the possibility to change the connection in .rpt files by an automated way like the schedule manager. This tool is a additional web application to deploy that can change the connection settings of rpt reports on thousands of reports in a few clicks. you can find it here :
http://www.sdn.sap.com/irj/scn/go/portal/prtroot/docs/library/uuid/80af7965-8bdf-2b10-fa94-bb21833f3db8
The last option is to do it with a small sdk script, for this purpose, a few lines of codes can change all the reports in a row.
After some implementations on linux to oracle database I would prefer also the native connection. ODBC and JDBC are deprecated ways to connect to database. You can use DATADIRECT connectors that are quite good but for volumes you will see the difference.

Access object attributes using other object JNI native method

Hi. I'm trying to change an attribute of object O1 from another object O2 without invoking a O1 method and without making the attribute as public or protected.
The only possibility that comes to my mind for doing so is writting a JNI native method
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static public native changeAttribute (Object O2, Object newAttributeValue) ;
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I know that is not a good practice but I cannot figure out another way.
I'll try to explain the whole problem so you see the reason. I'm working with transactions, using objects as the data. An object can be opened for write by several transactions because the granularity for conflicts is not the object, is each of its attributes. As long as two transaction don't write the same attribute, they both can write. For writing, each transactions uses a private copy of the object. At committing, the actual copy of the object must be replaced by the committer one, but as far as the granularity is the object attributes, only each written attribute must be replaced (if not, only the last commit would be visible).
This attribute replace must be done by the transaction manager as far as the transactional object is provided by the client. So what i was thinking was to use JNI or some trick like that to replace the object attributes transparently to the object.
I hope the explain is clear, my english is a little asleep :-(.
How to do it with reflection? I thought that was only for method calling. Anyway, there wouldn't be problems if the attributes are private?
Thanks for answering.
EDIT: I've been able to change a public field using reflection, but not the private one
import java.lang.reflect.*;
class Caca {
public static void main(String[] args) {
Integer r = new Integer(0);
System.out.println("original: " + r.toString());
modifyWidth(r, 300);
System.out.println("modified: " + r.toString());
static void modifyWidth(Integer r, int newValue ) {
Field valueField; Class c = r.getClass();
try {
valueField = c.getField("value");
valueField.set(r, newValue);
} catch (Exception e) { System.out.println(e); }
Message was edited by:
dfasdfsdafsadfasdf

JSP Best Practices and Oracle Report

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Would you use one SQL statement to retrieve all of the data for display Yes.
and use logic to avoid printing the redundant part of the dataNo.
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James : http://www.eclipselink.org

JSP & Native methods - Is JNI best practice?

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