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Groovy script reloading on runtime

I want to be a able to execute a groovy script from my Java application.
I want to reload the groovy script on runtime if needed. According to their tutorials, I can do something like that :
long now = System.currentTimeMillis();
for(int i = 0; i < 100000; i++) {
try {
GroovyScriptEngine groovyScriptEngine = new GroovyScriptEngine("");
System.out.println(groovyScriptEngine.run("myScript.groovy", new Binding()););
} catch (Exception e) {
e.printStackTrace();
}
}
long end = System.currentTimeMillis();
System.out.println("time " + (end - now));//24 secs
myScript.groovy
"Hello-World"
This works fine and the script is reloaded everytime i change a line in myScript.groovy.
The problem is that this is not time efficient, what it does is parsing the script from the file every time.
Is there any other alternative ? E.g something smarter that checks if the script is already parsed and if it did not change since the last parse do not parse it again.

<< edited due to comments >>
Like mentioned in one of the comments, separating parsing (which is slow) from execution (which is fast) is mandatory if you need performance.
For reactive reloading of the script source we can for example use the java nio watch service:
import groovy.lang.*
import java.nio.file.*
def source = new File('script.groovy')
def shell = new GroovyShell()
def script = shell.parse(source.text)
def watchService = FileSystems.default.newWatchService()
source.canonicalFile.parentFile.toPath().register(watchService, StandardWatchEventKinds.ENTRY_MODIFY)
boolean keepWatching = true
Thread.start {
while (keepWatching) {
def key = watchService.take()
if (key.pollEvents()?.any { it.context() == source.toPath() }) {
script = shell.parse(source.text)
println "source reloaded..."
}
key.reset()
}
}
def binding = new Binding()
def start = System.currentTimeMillis()
for (i=0; i<100; i++) {
script.setBinding(binding)
def result = script.run()
println "script ran: $result"
Thread.sleep(500)
}
def delta = System.currentTimeMillis() - start
println "took ${delta}ms"
keepWatching = false
The above starts a separate watcher thread which uses the java watch service to monitor the parent directory for file modifications and reloads the script source when a modification is detected. This assumes java version 7 or later. The sleep is just there to make it easier to play around with the code and should naturally be removed if measuring performance.
Storing the string System.currentTimeMillis() in script.groovy and running the above code will leave it looping twice a second. Making modifications to script.groovy during the loop results in:
~> groovy solution.groovy
script ran: 1557302307784
script ran: 1557302308316
script ran: 1557302308816
script ran: 1557302309317
script ran: 1557302309817
source reloaded...
script ran: 1557302310318
script ran: 1557302310819
script ran: 1557302310819
source reloaded...
where the source reloaded... lines are printed whenever a change was made to the source file.
I'm not sure about windows but I believe at least on linux that java uses the fsnotify system under the covers which should make the file monitoring part performant.
Should be noted that if we are really unlucky, the script variable will be reset by the watcher thread between the two lines:
script.setBinding(binding)
def result = script.run()
which would break the code as the reloaded script instance would not have the binding set. To fix this, we can for example use a lock:
import groovy.lang.*
import java.nio.file.*
import java.util.concurrent.locks.ReentrantLock
def source = new File('script.groovy')
def shell = new GroovyShell()
def script = shell.parse(source.text)
def watchService = FileSystems.default.newWatchService()
source.canonicalFile.parentFile.toPath().register(watchService, StandardWatchEventKinds.ENTRY_MODIFY)
lock = new ReentrantLock()
boolean keepWatching = true
Thread.start {
while (keepWatching) {
def key = watchService.take()
if (key.pollEvents()?.any { it.context() == source.toPath() }) {
withLock {
script = shell.parse(source.text)
}
println "source reloaded..."
}
key.reset()
}
}
def binding = new Binding()
def start = System.currentTimeMillis()
for (i=0; i<100; i++) {
withLock {
script.setBinding(binding)
def result = script.run()
println "script ran: $result"
}
Thread.sleep(500)
}
def delta = System.currentTimeMillis() - start
println "took ${delta}ms"
keepWatching = false
def withLock(Closure c) {
def result
lock.lock()
try {
result = c()
} finally {
lock.unlock()
}
result
}
which convolutes the code somewhat but keeps us safe against concurrency issues which tend to be hard to track down.

How to get an Initial Contex from Wildfly 8

ADDED 7/23.
Many views: Not even a "that's dumb" question in response. Can anyone at least tell me why such an embarrassingly trivial question seems to have no answer anywhere.
Q:
--- Have Wildfly 8 running on local machine localhost:9990.
--- Have a Java program that need's Wildfly's IntialContext.
--- Every reference says use: "Context ctx = new InitialContext(env);"
--- Yet a week of searching turns up no set of properties that returns one.
And no example of a java program that gets one.
Does no one ever do this? Really need help
Original Msg Below
I know many people have asked how to get an Initial context from Wildfly 8. But I have yet to find a simple answer with a simple example.
Therefore, I hope someone can tell my why this doesn’t work.
I start Wildfly with standalone-full.xml
The three sections below have
A - Code summary of my test Class whose only purpose is to secure an Initial Context. (I only removed a lot of printing code that produced the next section.]
B - The Eclipse console output for a failure.
C - Cut and paste code. Just in case anyone can help me get this to work. I’d like to leave behind something the next new WF user can cut and past and run. The only difference from 1 above is that this version has all the static methods I used to format the output. NOTE: I know the comments I inserted about the less than sign sound dumb. BUT ... they are true.
A Code Summary
import java.util.Properties;
import javax.naming.CommunicationException;
import javax.naming.Context;
import javax.naming.InitialContext;
public class JmsTestGetJNDIContext {
//members
final private Properties env = new Properties() {
private static final long serialVersionUID = 1L;
{
/* These are Properties used by a standalone JavaClient to secure a WIldFly InitialContext()*/
put(Context.INITIAL_CONTEXT_FACTORY, "org.jboss.naming.remote.client.InitialContextFactory");
put(Context.PROVIDER_URL,"http-remoting://localhost:9990");
put(Context.SECURITY_PRINCIPAL,"userGLB");
put(Context.SECURITY_CREDENTIALS,"Open");
put("jboss.naming.client.ejb.context", true);
/*The above URL, ID and PW successfully open Wildfly's Admin Console*/
}
};
//constructor
private JmsTestGetJNDIContext (){
/*print "beg"*/
/*print "env"*/
try {
/*print "Requesting InitialContext"*/
Context ctx = new InitialContext(this.env);
/*print "JNDI Context: " + ctx)*/
/*print "end");
} catch (CommunicationException e) {
/* print "You forgot to start WildFly dummy!"*/
} catch (Exception e) {
/* print"caught: " + e.getClass().getName()*/
/*print e.getMessage()*/
/* "end")*/
}
static public void main (String[] args) {
/*print "beg"*/
JmsTestGetJNDIContext client = new JmsTestGetJNDIContext ();
/*print "end"*/
}
}
B - Console Output
JmsTestGetJNDIContext.main () beg
JmsTestGetJNDIContext.<init> () beg
JmsTestGetJNDIContext.<init> () These are Properties used to obtain IntialContext
Key: java.naming.provider.url
Value: http-remoting://localhost:9990
Key: java.naming.factory.initial
Value: org.jboss.naming.remote.client.InitialContextFactory
Key: jboss.naming.client.ejb.context
Value: true
Key: java.naming.security.principal
Value: userGLB
Key: java.naming.security.credentials
Value: Open
JmsTestGetJNDIContext.<init> () Requesting InitialContext
JmsTestGetJNDIContext.<init> () caught: javax.naming.NamingException
JmsTestGetJNDIContext.<init> () Failed to create remoting connection
JmsTestGetJNDIContext.<init> () end
JmsTestGetJNDIContext.main () end
Cut and Paste Code
package org.america3.gotest.xtra;
import java.util.Properties;
import javax.naming.CommunicationException;
import javax.naming.Context;
import javax.naming.InitialContext;
public class JmsTestGetJNDIContext {
//members
final private Properties env = new Properties() {
/**
* Properties used by a standalone JavaClient to secure
* a WIldFly InitialContext()*/
private static final long serialVersionUID = 1L;
{
put(Context.INITIAL_CONTEXT_FACTORY,"org.jboss.naming.remote.client.InitialContextFactory");
put(Context.PROVIDER_URL, "http-remoting://localhost:9990");
put(Context.SECURITY_PRINCIPAL, "userGLB");
put(Context.SECURITY_CREDENTIALS, "Open");
// The above URL, ID and PW successfully open Wildfly's Admin Console
put("jboss.naming.client.ejb.context", true);
}
};
//constructor
private JmsTestGetJNDIContext (){/*ignore*/String iAm = JmsTestGetJNDIContext.getIAm(" ", Thread.currentThread().getStackTrace());
P (iAm, "beg");
pProps(iAm, env);
try {
P (sp + iAm, "Requesting InitialContext");
Context ctx = new InitialContext(this.env);
P (sp + iAm, "JNDI Context: " + ctx);
P (sp + iAm, "end");
} catch (CommunicationException e) {
P (sp + iAm, "You forgot to start WildFly dummy!");
} catch (Exception e) {
P (sp + iAm, "caught: " + e.getClass().getName());
P (sp + iAm, e.getMessage());
P (iAm, "end");
}
}
static public void main (String[] args) {/*ignore*/String iAm = JmsTestGetJNDIContext.getIAm("",Thread.currentThread().getStackTrace());
P (iAm, "beg");
JmsTestGetJNDIContext client = new JmsTestGetJNDIContext ();
P (iAm , "end");
}
/*The remaining static methods are just to facilitate printing.
* They are normally in a Untility package I add to my projects.
* I put them here so this code would run for anyone.*/
static private void pProps (String leader, Properties p) {
StringBuffer sb = new StringBuffer ();
String s = JmsTestGetJNDIContext.padRight(leader, 45, ' ');
s = " " + s + "These are Properties used to obtain IntialContext"+"\n";
sb.append(s);
String skip = "";
for (Object key: p.keySet()) {
sb.append(skip + " " + JmsTestGetJNDIContext.padRight("\""
+ (String)key + "\"", 40, ' ')
+ " \"" + p.get(key) + "\"");
skip = "\n";
}
System.out.println(sb);
}
static private void P (String s, String s2) {
System.out.println(s + s2);
}
static public String getClassMethodName (StackTraceElement[] elements) {
String className = null;
for (int i = 0; i * elements.length; i++]i ) {
/* You need to type in a less than sign for the '*'
* because when I do, the editor will not show any code
* that comes after it.
* I have no idea why, but I've spent over an hour trying,
* and every time I type a less than sign all the following
* code dissappears!*/
className = elements[i].getClassName ();
if (className.startsWith ("org.america3")) {
int end = className.lastIndexOf ('.');
return className.substring (end + 1) + "." + elements[i].getMethodName ();
} else {
continue;
}
}
return "no project method found in elements beginning with org.america3" ;
}
static private String getIAm (String indent, StackTraceElement[] elements) {
StringBuffer sb = new StringBuffer ();
sb.append(JmsTestGetJNDIContext.getClassMethodName(elements));
sb.append(" ()");
return indent + JmsTestGetJNDIContext.padRight (sb.toString(), 45, ' ') ;
}
static public String padRight(String s, int width, char c){
if (s == null) return "Null String";
if(s.length() ** width){
/* You need to type in a greater than or equal sign for
* the '**'see above.*/
return s;
} else {
StringBuffer sb = new StringBuffer();
sb.append (s);
for(int i = 0; i *** (width - s.length()); i++){
/*You need to type in a less than sign the '***'. Again see above*/
sb.append(c);
}
return sb.toString();
}
}
static public String sp = " ";
}

A while ago I also struggled with remote EJBs in my CLI application. I excavated a small example project that I wrote then. It gets an InitialContext and calls a remote EJB named AddBrackets:
import java.util.Properties;
import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import de.dnb.test.ejb.AddBrackets;
public final class Application {
public static void main(String[] args) throws NamingException {
final Properties jndiProperties = initJndiProperties();
final AddBrackets addBrackets = getEjb(jndiProperties);
System.out.println(addBrackets.processText("Hello World"));
}
private static Properties initJndiProperties() {
final Properties jndiProperties = new Properties();
jndiProperties.put(Context.INITIAL_CONTEXT_FACTORY,
"org.jboss.naming.remote.client.InitialContextFactory");
jndiProperties.put("jboss.naming.client.ejb.context", true);
jndiProperties.put(Context.PROVIDER_URL, "http-remoting://localhost:8080/");
//jndiProperties.put(Context.SECURITY_PRINCIPAL, "test");
//jndiProperties.put(Context.SECURITY_CREDENTIALS, "test");
return jndiProperties;
}
private static AddBrackets getEjb(Properties jndiProps)
throws NamingException {
final Context jndiContext = new InitialContext(jndiProps);
final String interfaceName = AddBrackets.class.getName();
return (AddBrackets) jndiContext.lookup(
"ejbtest-app-1.0-SNAPSHOT/ejbtest-ejb-1.0-SNAPSHOT/AddBracketsBean!"
+ interfaceName);
}
}
I built this program as a Maven project which had a dependency on
<dependency>
<groupId>org.wildfly</groupId>
<artifactId>wildfly-ejb-client-bom</artifactId>
<version>8.2.1.Final</version>
<type>pom</type>
</dependency>
This dependency brings in Wildfly's remote client EJB implementation and adds the following jars to the class path (links are to Maven Central):
jboss-logging-3.1.4.GA.jar
jboss-marshalling-1.4.9.Final.jar
jboss-marshalling-river-1.4.9.Final.jar
jboss-remoting-4.0.7.Final.jar
jboss-sasl-1.0.4.Final.jar
jboss-ejb-api_3.2_spec-1.0.0.Final.jar
jboss-transaction-api_1.2_spec-1.0.0.Final.jar
xnio-api-3.3.0.Final.jar
xnio-nio-3.3.0.Final.jar
jboss-ejb-client-2.0.1.Final.jar
jboss-remote-naming-2.0.1.Final.jar
wildfly-build-config-8.2.1.Final.jar
I did no special configuration on Wildfly to run this example. I simply downloaded a vanilla Wildfly 8.2.1, unzipped it, set up an admin user with the add-user.sh script and deployed my EJB in an EAR. As you can see above access is granted without a username and a password.
You can find the complete project including the AddBrackets EJB on my bitbucket account.
When I tried to get my head around remote EJBs with Wildfly, I found the article JBoss EAP / Wildfly – Three ways to invoke remote EJBs really helpful. It clearly describes the three different methods to access remote EJBs on Wildfly.

According to your own answer the following jars are on your classpath:
jboss-remote-naming-1.0.7.final.jar
jboss-logging.jar
xnio-api-3.0.7.ga.jar
jboss-remoting-3.jar
jboss-ejb-client-1.0.19.final.jar
You write that the application throws the following exception:
java.lang.NoSuchMethodError:
org.jboss.remoting3.Remoting.createEndpoint(Ljava/lang/String;Lorg/xnio/OptionMap;)Lorg/jboss/remoting3/Endpoint;]
This exception is thrown when org.jboss.naming.remote.client.EndpointCache which is part of the jboss-remote-naming jar tries to call Remoting.createEndpoint() which is contained in the jboss-remoting jar.
As you explain in your answer the reason for this is that the Remoting class declares a 3-parameter version of the createEndpoint() method while the EndpointCache class tries to call a 2-parameter version which does not exist.
I checked the commit histories and declared dependencies of the jboss-remote-naming and the jboss-remoting projects to find out what is going wrong there. This is what I found out:
The 2-parameter version of createEndpoint() was only added in version 3.2 of jboss-remoting. The pom.xml for jboss-remote-naming-1.0.7.final says it depends on jboss-remoting 3.2.7.GA.
As there is no version number on your jboss-remoting-3.jar, I guess it is an older version. You should be able to check this by looking for a pom.xml in META-INF folder of your jboss-remoting-3.jar. This should contain the version number.
To solve your problem, I suggest to replace your jboss-remoting-3.jar with jboss-remoting-3.2.7ga.jar or to use the set of jars I listed in my other answer.

I’ve decided the problem isn’t coding or the JNDI InititialContext Properties.
I mean the fatal error is a NoSuchMethodError. Therefore, as I confirmed in the WildFly server logs, my main method never even tries to connect.
Here’s what I think explains the real problem.
And I think it explains why there are so many calls for help with this error:
java.lang.NoSuchMethodError:
org.jboss.remoting3.Remoting.createEndpoint(Ljava/lang/String;Lorg/xnio/OptionMap;)Lorg/jboss/remoting3/Endpoint;]
Also why none of those calls for help ever get a conclusive answer. Just people suggesting different jars.
And since all those answers fixed on jars, this is how I tested the Build Path I was using:
First I removed all jars from the Build Path. Then I ran my one line main program till all ClassNotFoundException were gone.
First Error
java.lang.ClassNotFoundException:
org.jboss.naming.remote.client.InitialContextFactory]
Added jboss-remote-naming-1.0.7.final.jar to class path
Next Error
java.lang.NoClassDefFoundError:
org/jboss/logging/Logger
Added jboss-logging.jar
Next Error
java.lang.NoClassDefFoundError:
org/xnio/Options
Added xnio-api-3.0.7.ga.jar
Next Error
java.lang.NoClassDefFoundError:
org/jboss/remoting3/spi/ConnectionProviderFactory
Added jboss-remoting-3.jar
Next Error
java.lang.NoClassDefFoundError:
org/jboss/ejb/client/EJBClientContextIdentifier
Added jboss-ejb-client-1.0.19.final.jar
FATAL ERROR (note: All NoClassDefFoundError have been cleared)
java.lang.NoSuchMethodError:
org.jboss.remoting3.Remoting.createEndpoint(Ljava/lang/String;Lorg/xnio/OptionMap;)Lorg/jboss/remoting3/Endpoint;]
Then I used Eclipse’s Project Explorer to verify:
That jboss-remoting3.jar has the org.jboss.remoting3.Remoting Class. It does. That’s why there is no NoClassDefFoundError left above.
And verified it had this method:
public Endpoint createEndpoint (String, Executor, OptionMap) note: 3 parameters.
BUT the above Error indicates something is calling:
public Endpoint createEndpoint (String, OptionMap) note: 2 parameters.
That’s why the program throws a NoSuchMethodError. It is looking for a 2 paramater version of org.jboss.remoting3.Remoting.createEndpoint(). And the Remoting Class I have only has a 3 parameter version.`
I know this sounds impossible but the only thing I can think is there is an inconsistency in the Java API???
Clearly something is calling org.jboss.remoting3.Remoting.createEndpoint with 2 parameters.
But my org.jboss.remoting3.Remoting Class only has a 3 parameter version of the createEndpoint() Method.
So I’m going to clean this all up and repost a question asking how to explain the existence of a Class calling for a 2 paramter org.jboss.remoting3.Remoting.createEndpoint Method when I have a jar whose org.jboss.remoting3.Remoting only offers a 3-parameter.

Here is your obligatory "that's a dumb question." Does the wildfly remote quickstart github repo answer the question for you? Their code, from RemoteEJB.java
final Hashtable<String, String> jndiProperties = new Hashtable<>();
jndiProperties.put(Context.URL_PKG_PREFIXES, "org.jboss.ejb.client.naming");
final Context context = new InitialContext(jndiProperties);
return (RemoteCalculator) context.lookup("ejb:/ejb-remote-server-side/CalculatorBean!" + RemoteCalculator.class.getName());

get DFS/UNC info progromatically - Java

Ok I'll try and keep this short.
First let me explain exactly what I am trying to get. If you open Windows Explorer and go to a network drive there is a DFS tab there(must have DFS enabled VIA the servers on the network so it may not be there).
In that tab there is a list called the "Referral List"... I want what is in that box. I believe this is the DFS or UNC, you can correct me it will help me.
What I have is the \domainname.com\something$\BUS\blah\myDriveHome but this is tied to something else in that box that contains the actual server that that share is setting on and that share is what I need to run a compliance check.
I cannot use an exe that is not package with Windows 7 not any other exe as we cannot distribute exes.
So what have I done... a VERY thorough search for things like DFS/UNC paths from the command line, powershell, and registry and no go. Command line "net use" only return the linked path and not the server so that is useless.
I only ever post a question when I hit a wall that is taking up to much programming time.
If anyone has an info it would be grateful.
Thanks

I was able to steal the C# code in this answer here and make some modifications so it works with .Net 2.0, and use it within PowerShell:
$dfsCode = #'
using System;
using System.Runtime.InteropServices;
public static class Dfs
{
private enum NetDfsInfoLevel
{
DfsInfo1 = 1,
DfsInfo2 = 2,
DfsInfo3 = 3,
DfsInfo4 = 4,
DfsInfo5 = 5,
DfsInfo6 = 6,
DfsInfo7 = 7,
DfsInfo8 = 8,
DfsInfo9 = 9,
DfsInfo50 = 50,
DfsInfo100 = 100,
DfsInfo150 = 150,
}
[DllImport("netapi32.dll", SetLastError = true)]
private static extern int NetApiBufferFree(IntPtr buffer);
[DllImport("Netapi32.dll", CharSet = CharSet.Unicode, SetLastError = true)]
private static extern int NetDfsGetInfo(
[MarshalAs(UnmanagedType.LPWStr)] string DfsEntryPath, // DFS entry path for the volume
[MarshalAs(UnmanagedType.LPWStr)] string ServerName, // This parameter is currently ignored and should be NULL
[MarshalAs(UnmanagedType.LPWStr)] string ShareName, // This parameter is currently ignored and should be NULL.
NetDfsInfoLevel Level, // Level of information requested
out IntPtr Buffer // API allocates and returns buffer with requested info
);
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
private struct DFS_INFO_3
{
[MarshalAs(UnmanagedType.LPWStr)]
public string EntryPath;
[MarshalAs(UnmanagedType.LPWStr)]
public string Comment;
public int State;
public int NumberOfStorages;
public IntPtr Storage;
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
private struct DFS_STORAGE_INFO
{
public int State;
[MarshalAs(UnmanagedType.LPWStr)]
public string ServerName;
[MarshalAs(UnmanagedType.LPWStr)]
public string ShareName;
}
private static T GetStruct<T>(IntPtr buffer, int offset)where T:struct
{
T r = new T();
r = (T) Marshal.PtrToStructure((IntPtr)((long)buffer + offset * Marshal.SizeOf(r)), typeof(T));
return r;
}
public static string GetDfsInfo(string server)
{
string rval = null;
IntPtr b;
int r = NetDfsGetInfo(server, null, null, NetDfsInfoLevel.DfsInfo3, out b);
if(r != 0)
{
NetApiBufferFree(b);
// return passed string if not DFS
return rval;
}
DFS_INFO_3 sRes = GetStruct<DFS_INFO_3>(b,0);
if(sRes.NumberOfStorages > 0)
{
DFS_STORAGE_INFO sResInfo = GetStruct<DFS_STORAGE_INFO>(sRes.Storage,0);
rval = string.Concat(#"\\", sResInfo.ServerName, #"\", sResInfo.ShareName, #"\");
}
NetApiBufferFree(b);
return rval;
}
}
'#
Add-Type -TypeDefinition $dfsCode
[Dfs]::GetDfsInfo('\\ad.domain.com\Share')
This code will work with PowerShell 2.0 which is included with Windows 7.

I went another direction with the use of PSEXEC and DFSUtil to find the DFS info VIA the remote PC. Returns a lot of info but I filtered it in PowerShell after reading the file and matching the UNC. I would post the how to but I had to do some major adapting on my end with the info that is on a few other sites for DFSUtil and what to look for and PSExec. I will note this for PSEXEC:
cmd.exe /s /c C:\Temp\psexec.exe 2> $null
That "2> $null" will save you some headaches and your script crashing if the return is in the error channel. You will need to run it in the PS console though without that to catch the error, but when you have a script like mine performing 50+ system checks you don't want the whole thing to halt for just one error.

JavaScript ScriptEngine isn't working within Google App Engine for Java (GAE/J)

I am having an issue where I always get a 0 value returned when I try to use the ScriptEngine eval. By using Logger, I was able to determine that there are NullPointerExceptions being generated. After further inspection, it appears that GAE doesn't always return a valid script engine (if ever), because it throws an exception when you try to use it.
My code looks like:
public double myEval(String JsFormulaStr ) {
double solutionValue = 0;
ScriptEngineManager mgr = new ScriptEngineManager();
ScriptEngine eng = mgr.getEngineByName("JavaScript");
if(eng == null) { // Added this block of code to prevent java.lang.NullPointerException...
log.severe("Unable to get Script Engine." );
return 0;
}
try {
Object jsResults = eng.eval(JsFormulaStr);
solutionValue = Double.parseDouble(jsResults.toString());
return solutionValue;
} catch(Exception e) {
log.severe("[ERROR] in getCalculatedSolution_FromJS_ToDouble()::\n\t" +
"Formula String is: " + JsFormulaStr + "\n\t" + e);
return 0;
}
}
Everything works fine if I run it locally as a WebApp (Both in Eclipse & Netbeans. And within Tomcat & Glassfish 4.0).
Some of the strings which I tried to eval:
62.0 / 100
0.0 * 352.0
(0 - 428) * 1000
(0 - 597) * 1000
73.0 / 100
NOTE: The 0's or 0.0's are from other evaluations which have failed in previous calls. Since this function returns 0 on error.
According to Google's JRE Class Whitelist, the ScriptEngineManager and ScriptEngine classes are allowed. So I don't understand why it isn't working as expected.
Any suggestions?
Thanks in advance,
Randy

I've hit the same problem. Although the classes are whitelisted, it seems like their functionality is limited on App Engine. The code works fine on your local machine but fails when deployed to App Engine as there aren't any script engines available (hence the NullPointerException).
Luckily, you can do the same thing using the Rhino engine.
Note: this example builds on that given by Harsha R in https://stackoverflow.com/a/19828128/578821
Download the Rhino Jar and add js.jar to your classpath (you only need js-14.jar if you're using Java 1.4).
/* Example 1: Running a JavaScript function (taken from examples) */
String script = "function abc(x,y) {return x+y;}";
Context context = Context.enter();
try {
ScriptableObject scope = context.initStandardObjects();
Scriptable that = context.newObject(scope);
Function fct = context.compileFunction(scope, script, "script", 1, null);
Object result = fct.call(context, scope, that, new Object[] { 2, 3 });
System.out.println(Context.jsToJava(result, int.class));
}
finally {
Context.exit();
}
/* Example 2: execute a JavaScript statement */
script = "3 + 2 * (4*5)";
context = Context.enter();
try{
Scriptable scope = context.initStandardObjects();
Object result = context.evaluateString(scope, script, "<cmd>", 1, null);
System.out.println(result);
}
finally{
Context.exit();
}

Getting output parameter value set by VBScript (WMI) method in java via JACOB

Am trying to convert a VBScript to java using JACOB - Java COM bridge library.
'Create' method in VBScript accepts a [out] param in it's method and it sets it upon method execution and i couldn't figure out how to retrieve it back via JACOB.
VBScript in question:
Function CreateProcess(strComputer, strCommand)
Dim objWMIService, objProcess
Set objWMIService = GetObject("winmgmts:" & "{impersonationLevel=impersonate}!\\" & strComputer & "\root\cimv2")
Set objProcess = objWMIService.Get("Win32_Process")
errReturn = objProcess.Create (strCommand, Null, Null, intProcessID)
Set objWMIService = Nothing
Set objProcess = Nothing
CreateProcess = intProcessID
End Function
intProcessID is [out] param set after method execution. (Create API contract)
Converted java code(incomplete and modified slightly for demonstration):
public static void createProcess() {
String host = "localhost";
String connectStr = String
.format("winmgmts:{impersonationLevel=impersonate}!\\\\%s\\root\\CIMV2",
host);
ActiveXComponent axWMI = new ActiveXComponent(connectStr);
Variant vCollection = axWMI.invoke("get", new Variant("Win32_Process"));
Dispatch d = vCollection.toDispatch();
Integer processId = null;
int result = Dispatch.call(d, "Create", "notepad.exe", null, null, processId)
.toInt();
System.out.println("Result:" + result);
// WORKS FINE until here i.e. notepad launches properly, however processId still seems to be null. Following commented code is wrong - doesn't work
//Variant v = Dispatch.get(d, "processId"); // even ProcessId doesn't work
//int pId = v.getInt();
//System.out.println("process id:"
// + pId);
// what is the right way to get the process ID set by 'Create' method?
}
Would be great if you could provide some pointers or relevant code. Ask me more if needed. Thanks in advance.

Replacing
Integer processId = null;
with
Variant processId = new Variant(0, true);
should solve the problem. You should then have process ID of the notepad.exe process in the processId variant, and it can be fetched by
processId.getIntRef()