JNI and Socket
Hello,
I have a java application that calls "runtime.exec(Software.exe, parameter);"
The Software.exe starts and is trying to get TCP/IP connection.
Response error: "Software.exe can't open TCP/IP".
Usually Software.exe starts without error.
Thank you for your help!
Best regards,
Can you run that program alone, independently of Java?
Similar Messages
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I am trying to write a Java library around a piece of hardware that currently does not support Java. As the first part of the task, I need to establish a TCP/IP connection between a client and server. I wrote some test code in C that is very simple socket code that can be found on tons of example sites (yes I know Java has built in classes for this, but the connection must exist in the native side).
I wrapped everything into a simple ConnectToServer and ConnectToClient functions (everything is hardcoded, so no parameters are passed) in a .so and can establish and run the connection without a hitch in a C++ program that loads the .so. When I load the .so and try to call the functions in a Java harness, the JVM crashes with a SIGSEGV in the server side during the accept call (the client does establish the connection, so it must be crashing somewhere pretty far into the accept( ) call). I have verified this crash by building and running the debug version of hotspot in gdb.
Im running Red Hat Enterprise Linux Server release 6.1 (Santiago) and Java VM: Java HotSpot(TM) 64-Bit Server VM (21.0-b17 mixed mode linux-amd64 compressed oops).
Am I not allowed to call native library functions that have system calls in them during JNI, or am I missing something else that is not immediately obvious?jschell wrote:
891860 wrote:
I am trying to write a Java library around a piece of hardware that currently does not support Java. As the first part of the task, I need to establish a TCP/IP connection between a client and server. I wrote some test code in C that is very simple socket code that can be found on tons of example sites (yes I know Java has built in classes for this, but the connection must exist in the native side).Only reason I can think of for that would be because you need to pass the socket to your C code.
So given that.
1. Write C code that creates the socket
2. Write an API in C that uses 1 to call the library.
3. Test 1 and 2 via C code.
After step 3 is complete you do the following.
A. Determine the business functionality that your java application needs to access via the library. This step does not involve code at all. No C. No java.
B. Write an API in C that implements the functionality determined in step A. And it will use code from 1/2 as well as needed.
C. Write code in C to test B.
After you have completed step 3 and step C then you write JNI and Java.Yes, the case is that the library that Im using for this device is in C, and requires a C socket. I did pretty much the steps that you mentioned. I wrote the basic network code. I wrapped it. Then I wrote a C program to load the .so and test it. It worked fine. When I added the JNI wrapper and Java code to launch it, that is when I had the problems.
I removed everything but the basic TCP IP code (literally the wrapper that goes into JNI is just the TCP connection code). It still crashed. I then replaced the TCP IP code with another example I found on the net. Same issue. :(
Edited by: 891860 on 17-Oct-2011 15:55 -
JVM Crash When Using JNI and COM
I'm trying to call a DLL compiled from VB6 source code that I do not have access to. The VB6 code simply retrieves data from a DB2 database using ADO and my client code grabs that data and marshals it to my Java code. I'm attempting to achieve this using JNI and COM (without a third-party bridge). It works 75% of the time, but the other 25% of the time, the JVM crashes with the usual Hotspot crash log containing an access violation exception. However, I don't know what in my C++ code (VC++ 8) could be causing this except for passing a "wild" pointer to the code lying underneath the COM object interface. If that is the case, I don't know how I am doing that.
The Java code that is calling my native method is running on Tomcat 5.5.25 and just to be safe, I am not allowing multiple threads to concurrently call the method in my JNI DLL (though I realize that this will kill performance). Once I can get past this problem, I'll do the COM interfacing on a worker thread in my native code so I don't screw up CoInitialize and CoUninitialize calls in the case the same thread is concurrently executing multiple calls to my native code.
I've noticed that in most cases, the JVM crashes during my call to the pClsAccount->OpenConnection method. However, my DLL isn't what is listed on the top of the call stack, which is why I suspect the passing of a wild pointer, though I'm just taking a guess at that. Does anyone have an idea as to what's going on ?
JNIEXPORT jobject JNICALL Java_CustomerInfo_nGetCustomerAccountInfo(JNIEnv *env, jobject customerInfo, jstring accountNumber, jstring iniFileName)
jboolean isCopy;
// Account info class and instance to be instantiated
jclass accountInfoCls = NULL;
jobject accountInfoObj = NULL;
// The constructor ID of the accountInfoCls
jmethodID ctorID = NULL;
// Pointer to the interface for the ClsAccount COM object
_clsAccount *pClsAccount = NULL;
HRESULT hr;
BSTR bstrIniFileName(L"");
try
const char *nativeAccountNumber = NULL;
if (accountNumber != NULL)
nativeAccountNumber = env->GetStringUTFChars(accountNumber, &isCopy);
else
jclass newExcCls;
env->ExceptionDescribe();
env->ExceptionClear();
newExcCls = env->FindClass("java/lang/IllegalArgumentException");
env->ThrowNew(newExcCls, "accountNumber passed in was null !");
return NULL;
// Initialization
variantt varConnectionSucceeded = variantt(false);
variantt varGetAccountInfoSucceeded = variantt(false);
variantt varAccountNumber = variantt(nativeAccountNumber);
bstrt bstrLastPaymentDate = bstrt();
bstrt bstrLastErrorMessage = bstrt();
bstrt bstrLastErrorNumber = bstrt();
jlong jTotalDue = NULL;
jlong jEstablishedDueDay = NULL;
jlong jLastPaymentAmount = NULL;
jstring jLastPaymentDate = NULL;
jstring jLastErrorMessage = NULL;
jstring jLastErrorNumber = NULL;
jthrowable jException = NULL;
const char *chLastPaymentDate = NULL;
const char *chLastErrorMessage = NULL;
const char *chLastErrorNumber = NULL;
long long totalDue;
long long lastPaymentAmount;
long establishedDueDateDay;
//Convert string from Java string to C string to VB string
const char *nativeIniFileName = NULL;
if (iniFileName != NULL)
nativeIniFileName = env->GetStringUTFChars(iniFileName, &isCopy);
else
jclass newExcCls;
env->ExceptionDescribe();
env->ExceptionClear();
newExcCls = env->FindClass("java/lang/IllegalArgumentException");
env->ThrowNew(newExcCls, "iniFileName passed in was null");
return NULL;
bstrIniFileName = comutil::ConvertStringToBSTR(nativeIniFileName);
CoInitialize(NULL);
// Create an instance of the COClass with the interface over it
hr = CoCreateInstance(__uuidof(clsAccount), NULL, CLSCTX_INPROC_SERVER, __uuidof(_clsAccount), (void **)&pClsAccount);
if (hr == S_OK)
varConnectionSucceeded.boolVal = pClsAccount->OpenConnection(&bstrIniFileName);
　
if (varConnectionSucceeded.boolVal == -1)
varGetAccountInfoSucceeded.boolVal = pClsAccount->GetAccountPaymentInformation(&(varAccountNumber.GetVARIANT()));
env->ReleaseStringUTFChars(accountNumber, nativeAccountNumber);
// Extract all available account information from the ClsAccount object
if (varGetAccountInfoSucceeded.boolVal == -1)
totalDue = pClsAccount->TotalDue.int64;
establishedDueDateDay = pClsAccount->EstablishedDueDateDay;
lastPaymentAmount = pClsAccount->LastPaymentAmount.int64;
bstrLastPaymentDate = pClsAccount->LastPaymentDate;
chLastPaymentDate = comutil::ConvertBSTRToString(bstrLastPaymentDate.GetBSTR());
jTotalDue = (jlong)totalDue;
jEstablishedDueDay = (jlong)establishedDueDateDay;
jLastPaymentAmount = (jlong)lastPaymentAmount;
jLastPaymentDate = env->NewStringUTF(chLastPaymentDate);
delete[] chLastPaymentDate;
pClsAccount->CloseConnection();
// Populate error fields if any errors occur
bstrLastErrorMessage = pClsAccount->LastErrMessage;
chLastErrorMessage = comutil::ConvertBSTRToString(bstrLastErrorMessage.GetBSTR());
bstrLastErrorNumber = pClsAccount->LastErrNumber;
chLastErrorNumber = comutil::ConvertBSTRToString(bstrLastErrorNumber.GetBSTR());
jLastErrorMessage = env->NewStringUTF(chLastErrorMessage);
jLastErrorNumber = env->NewStringUTF(chLastErrorNumber);
delete[] chLastErrorMessage;
delete[] chLastErrorNumber;
const char* clsName = "com/nuance/merchantsmutual/businessentities/CustomerAccountInfo";
// Find the Java class and the ID of its constructor
accountInfoCls = env->FindClass(clsName);
ctorID = env->GetMethodID(accountInfoCls, "<init>", "(JJJLjava/lang/String;Ljava/lang/String;Ljava/lang/String;)V");
jException = env->ExceptionOccurred();
if (jException != NULL)
env->ExceptionDescribe();
env->ExceptionClear();
//Release all resources associated with the ClsAccount instance
pClsAccount->Release();
//Instantiate the class with the given parameters
accountInfoObj = env->NewObject(accountInfoCls, ctorID, jTotalDue, jEstablishedDueDay, jLastPaymentAmount, jLastPaymentDate, jLastErrorMessage, jLastErrorNumber);
jException = env->ExceptionOccurred();
if (jException != NULL)
env->ExceptionDescribe();
env->ExceptionClear();
else if (hr == REGDB_E_CLASSNOTREG)
cout << "COM class not registered" << endl;
else if ( hr == CLASS_E_NOAGGREGATION)
cout << "COM class can't be aggregated" << endl;
else if (hr == E_NOINTERFACE)
cout << "No interface for COM class clsAccount" << endl;
else if (hr == E_POINTER)
cout << "*ppv pointer was NULL !" << endl;
else
cout << "Error occurred while creating COM object. HR is [" << hr << "]" << endl;
// Free the BSTR because a new one was returned with a call to comutil::ConvertStringToBSTR
SysFreeString(bstrIniFileName);
// Release the string when it's no longer needed. MUST call if string won't be used
// anymore or else a memory leak will occur
env->ReleaseStringUTFChars(iniFileName, nativeIniFileName);
CoUninitialize();
　
catch (_com_error &e)
cout << "Encountered an exception in GetCustomerAccountInfo: Error was " << e.ErrorMessage();
pClsAccount->Release();
catch (...)
pClsAccount->Release();
return accountInfoObj;
Edited by: Cthulhu76 on Jan 5, 2010 9:18 AM0x49202400 JavaThread "ContainerBackgroundProcessor[StandardEngine[Catalina]]" daemon [_thread_blocked, id=5340, stack(0x49bf0000,0x49c40000)]
0x48a7e800 JavaThread "Thread-1" [_thread_in_native, id=5976, stack(0x48f00000,0x48f50000)]
0x48a0dc00 JavaThread "Low Memory Detector" daemon [_thread_blocked, id=3072, stack(0x48c60000,0x48cb0000)]
0x48a09000 JavaThread "CompilerThread0" daemon [_thread_blocked, id=4988, stack(0x48c10000,0x48c60000)]
0x48a07c00 JavaThread "Attach Listener" daemon [_thread_blocked, id=3124, stack(0x48bc0000,0x48c10000)]
0x48a07000 JavaThread "Signal Dispatcher" daemon [_thread_blocked, id=2572, stack(0x48b70000,0x48bc0000)]
0x489f5c00 JavaThread "Finalizer" daemon [_thread_blocked, id=5752, stack(0x48b20000,0x48b70000)]
0x489f4c00 JavaThread "Reference Handler" daemon [_thread_blocked, id=2596, stack(0x48ad0000,0x48b20000)]
0x003c6000 JavaThread "main" [_thread_in_native, id=4252, stack(0x00820000,0x00870000)]
Other Threads:
0x489f0400 VMThread [stack: 0x48a80000,0x48ad0000] [id=5624]
0x48a18800 WatcherThread [stack: 0x48cb0000,0x48d00000] [id=1192]
VM state:not at safepoint (normal execution)
VM Mutex/Monitor currently owned by a thread: None
Heap
def new generation total 36288K, used 12762K [0x02940000, 0x050a0000, 0x07800000)
eden space 32256K, 34% used [0x02940000, 0x0343af58, 0x048c0000)
from space 4032K, 37% used [0x04cb0000, 0x04e2ba28, 0x050a0000)
to space 4032K, 0% used [0x048c0000, 0x048c0000, 0x04cb0000)
tenured generation total 483968K, used 7518K [0x07800000, 0x250a0000, 0x42940000)
the space 483968K, 1% used [0x07800000, 0x07f57958, 0x07f57a00, 0x250a0000)
compacting perm gen total 14080K, used 14016K [0x42940000, 0x43700000, 0x46940000)
the space 14080K, 99% used [0x42940000, 0x436f0320, 0x436f0400, 0x43700000)
No shared spaces configured.
Dynamic libraries:
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0x7c800000 - 0x7c8c0000 C:\WINDOWS\system32\ntdll.dll
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0x77420000 - 0x77523000 C:\WINDOWS\WinSxS\x86_Microsoft.Windows.Common-Controls_6595b64144ccf1df_6.0.3790.3959_x-ww_D8713E55\comctl32.dll
0x6d7c0000 - 0x6da10000 C:\Program Files\Java\jre1.6.0_07\bin\client\jvm.dll
0x76aa0000 - 0x76acd000 C:\WINDOWS\system32\WINMM.dll
0x7c340000 - 0x7c396000 C:\WINDOWS\system32\MSVCR71.dll
0x6d270000 - 0x6d278000 C:\Program Files\Java\jre1.6.0_07\bin\hpi.dll
0x76b70000 - 0x76b7b000 C:\WINDOWS\system32\PSAPI.DLL
0x6d770000 - 0x6d77c000 C:\Program Files\Java\jre1.6.0_07\bin\verify.dll
0x6d310000 - 0x6d32f000 C:\Program Files\Java\jre1.6.0_07\bin\java.dll
0x6d7b0000 - 0x6d7bf000 C:\Program Files\Java\jre1.6.0_07\bin\zip.dll
0x6d570000 - 0x6d583000 C:\Program Files\Java\jre1.6.0_07\bin\net.dll
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0x71bf0000 - 0x71bf8000 C:\WINDOWS\system32\WS2HELP.dll
0x71b20000 - 0x71b61000 C:\WINDOWS\system32\mswsock.dll
0x5f270000 - 0x5f2ca000 C:\WINDOWS\system32\hnetcfg.dll
0x71ae0000 - 0x71ae8000 C:\WINDOWS\System32\wshtcpip.dll
0x76ed0000 - 0x76efa000 C:\WINDOWS\system32\DNSAPI.dll
0x76f70000 - 0x76f77000 C:\WINDOWS\System32\winrnr.dll
0x76f10000 - 0x76f3e000 C:\WINDOWS\system32\WLDAP32.dll
0x76f80000 - 0x76f85000 C:\WINDOWS\system32\rasadhlp.dll
0x4a6a0000 - 0x4a6ac000 C:\Program Files\Apache Software Foundation\Tomcat 5.5\webapps\MMI\WEB-INF\lib\CustomerInfoProxy.dll
0x77670000 - 0x777a9000 C:\WINDOWS\system32\ole32.dll
0x77d00000 - 0x77d8b000 C:\WINDOWS\system32\OLEAUT32.dll
0x7c420000 - 0x7c4a7000 C:\WINDOWS\WinSxS\x86_Microsoft.VC80.CRT_1fc8b3b9a1e18e3b_8.0.50727.4053_x-ww_E6967989\MSVCP80.dll
0x78130000 - 0x781cb000 C:\WINDOWS\WinSxS\x86_Microsoft.VC80.CRT_1fc8b3b9a1e18e3b_8.0.50727.4053_x-ww_E6967989\MSVCR80.dll
0x777b0000 - 0x77833000 C:\WINDOWS\system32\CLBCatQ.DLL
0x77010000 - 0x770d6000 C:\WINDOWS\system32\COMRes.dll
0x77b90000 - 0x77b98000 C:\WINDOWS\system32\VERSION.dll
0x75da0000 - 0x75e5d000 C:\WINDOWS\system32\SXS.DLL
0x75e60000 - 0x75e87000 C:\WINDOWS\system32\apphelp.dll
0x4dc30000 - 0x4dc5e000 C:\WINDOWS\system32\msctfime.ime
0x4b0d0000 - 0x4b395000 C:\WINDOWS\system32\xpsp2res.dll
0x71bb0000 - 0x71bb9000 C:\WINDOWS\system32\WSOCK32.dll
0x4bbe0000 - 0x4bbea000 C:\Program Files\Apache Software Foundation\Tomcat 5.5\webapps\MMI\WEB-INF\lib\ClearTranProxy.dll
0x745e0000 - 0x7489e000 C:\WINDOWS\system32\msi.dll
0x71c40000 - 0x71c97000 C:\WINDOWS\system32\NETAPI32.dll
0x4bc50000 - 0x4bc6c000 C:\WINDOWS\system32\DBNETLIB.DLL
0x71f60000 - 0x71f64000 C:\WINDOWS\system32\security.dll
0x76c90000 - 0x76cb7000 C:\WINDOWS\system32\msv1_0.dll
0x76cf0000 - 0x76d0a000 C:\WINDOWS\system32\iphlpapi.dll
0x761b0000 - 0x76243000 C:\WINDOWS\system32\crypt32.dll
0x76190000 - 0x761a2000 C:\WINDOWS\system32\MSASN1.dll
0x4bcf0000 - 0x4bcff000 C:\Program Files\Common Files\System\Ole DB\SQLOLEDB.RLL
0x4a8a0000 - 0x4a8aa000 C:\Program Files\Apache Software Foundation\Tomcat 5.5\webapps\MMI\WEB-INF\lib\MIGI.DLL
0x73570000 - 0x736c2000 C:\Program Files\Apache Software Foundation\Tomcat 5.5\webapps\MMI\WEB-INF\lib\MSVBVM60.DLL
0x4a950000 - 0x4a9e2000 C:\Program Files\Common Files\System\ado\msado15.dll
0x74a50000 - 0x74a6a000 C:\WINDOWS\system32\MSDART.DLL
0x4c850000 - 0x4c8c9000 C:\Program Files\Common Files\System\Ole DB\oledb32.dll
0x4dbb0000 - 0x4dbc1000 C:\Program Files\Common Files\System\Ole DB\OLEDB32R.DLL
VM Arguments:
jvm_args: -Dcatalina.home=C:\Program Files\Apache Software Foundation\Tomcat 5.5 -Dcatalina.base=C:\Program Files\Apache Software Foundation\Tomcat 5.5 -Djava.endorsed.dirs=C:\Program Files\Apache Software Foundation\Tomcat 5.5\common\endorsed -Djava.io.tmpdir=C:\Program Files\Apache Software Foundation\Tomcat 5.5\temp -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -Djava.util.logging.config.file=C:\Program Files\Apache Software Foundation\Tomcat 5.5\conf\logging.properties -Djava.library.path=C:\Program Files\Apache Software Foundation\Tomcat 5.5\webapps\MMI\WEB-INF\lib vfprintf -Xms512m -Xmx1024m
java_command: <unknown>
Launcher Type: generic
Environment Variables:
JAVA_HOME=C:\Program Files\Java\jdk1.6.0_07
[error occurred during error reporting (printing environment variables), id 0xc0000005]
--------------- S Y S T E M ---------------
OS: Windows Server 2003 family Build 3790 Service Pack 2
CPU:total 4 (4 cores per cpu, 1 threads per core) family 6 model 7 stepping 6, cmov, cx8, fxsr, mmx, sse, sse2, sse3, ssse3
Memory: 4k page, physical 2097151k(2097151k free), swap 4194303k(4194303k free)
vm_info: Java HotSpot(TM) Client VM (10.0-b23) for windows-x86 JRE (1.6.0_07-b06), built on Jun 10 2008 01:14:11 by "java_re" with MS VC++ 7.1
time: Mon Dec 28 15:24:00 2009
elapsed time: 600 seconds -
Java 1.5 JNI and C++ exception
Hello, All
I've troubles with handling C++ exceptions using JNI and shared library. I'm using Java 1.5_06, RedHat 7.3 and JBoss 4.0.5
From Java class I call JNI a method in my shared library(libx.so) which calls a method in other shared library(liby.so). Liby.so uses Xerces library. During parsing process an exception occurs. But according to Xerces sources it's a normal behavior and should be caught. But instead I've got SIGNABRT in JVM and a core dump will created. What's wrong? Backtrace shows similar something:
XXXXX __default_terminate() ....
XXXXX __terminate() ....
XXXXX __throws
XXXXX C++ method ..
XXXXX.....
XXXXX.....
XXXXX JNI methodI found similar bugs reports in the forum. But they says about Java 1.4 version and according to bugs descriptions it should be already fixed.
Message was edited by:
kostik78The question is closed. The root cause was incorrect building of shared library.
-
Java Swing and Socket Programming
I am making a Messenger like yahoo Messenger using Swing and Socket Programming ,Multithreading .
Is this techology feasible or i should try something else.
I want to display my messenger icon on task bar as it comes when i install and run Yahoo Messenger.
Which class i should use.I don't really have an answer to what you are asking. But I am developing the same kind of application. I am using RMI for client-server and server-server (i have distributed servers) communication and TCP/IP for client-client. So may be we might be able to help each other out. My email id is [email protected]
Are you opening a new socket for every conversation? I was wondering how to multithread a socket to reuse it for different connections, if it is possible at all.
--Poonam. -
Network and socket programming in python
i want to learn network and socket programming but i would like to do this in python.Reason behind this is that python is very simple and the only language i know .
anybody can suggest me which book should i pick.
the book should have following specification--
1)not tedious to follow
2)lots of example
3)starts with some networking stuff and then get into codes
thanks in advance with regards.hmm. well, your requirements are almost contradictory.
Not sure about books, except maybe dusty's.
Most python books cover at least some network programming (unless the book is topic specific).
I use lots of python-twisted at work. I mean ALOT. I wouldn't recommend it to someone looking for non-tedious though! I also like gevent/eventlet (esp. the async socket wrappers).
EDIT: Wow. My post wasn't really helpful at all. Sorry!
Last edited by cactus (2010-09-04 09:16:54) -
What is the Difference btwn PORT and SOCKET
Hai, what is the diff. between Port and Socket and is Port related to Hardware?
Or another way, A socket is the connection you make, the port is the channel that the socket connected on.
A lot of ports are assigned to a certain use eg 80 = http. So when you try to access a web page, your browser tries to make a connection to the server on port 80, the server software will listen on port 80 on the server computer for htp request. -
Hi,
At my job, we seem to have a memory leak related to JNI. We know we
have a memory leak because we keep getting Out of Memory errors even
after increasing the maximum heap size to more than 256 megs. And we
know that this is the application that is eating up all the system
memory.
We are running under Windows 2000, with both JDK 1.3.0 and JDK 1.4.1.
We tried looking at the problem under JProbe, but it shows a stable
Java heap (no problems, except that the Windows task manager shows it
growing and growing...)
I tried a strip down version, where I set the max heap size to 1 Meg,
and print out the total memory, memory used, and maximum memory used at
a 5 sec interval.
Memory used = Runtime.getRuntime().totalMemory() - Runtime.getRuntime().freeMemory().
Well, I let that strip down version running for about a day. The
maximum memory used has stabilized to about 1.1 Meg, and has not
increased. The current memory used increases until it gets to some
threshold, then it decreases again. However, the Windows task manager
shows the memory increasing -- and currently it is at 245 Megs!
In the lab, the behavior we see with the Windows task manager is as
follows:
1. Total memory used in the system increases until some threshold.
2. Then it goes back down by about 100 Megs.
3. This cycle continues, but at each cycle the memory goes back down
less and less, until the app crashes.
Now, our theory is that JNI is consuming all this memory (maybe we are
using JNI wrong). That's the only explanation we can come up with to
explain what we have seen (Java showing an OK heap, but the task
manager showing it growing, until crashing).
Does that make sense? Can the new operator throw an Out of Memory
error if the system does not have enough memory to give it, even if
there is still free heap space as far as the Runtime object is
concerned? Does the Runtime object figures objects allocated through
JNI methods into the heap used space?
Note that I know the task manager is not a reliable indicator.
However, I don't think a Java app is supposed to runaway with system
memory -- the problem is not simply that the Java app is consuming too
much memory, but that it seems to always want more memory. Besides, we
do get the Out of Memory error.
Thanks for your help,
Nicolas RiveraHi,
there are two sources of memory leakage in JNI:
- regular leaks in c/c++ code;
- not released local/global references of java objects in JNI.
I think that the first issue in not a problem for you. The second is more complex. In your JNI code you should check
- how many local references alive you keep in your code as their number is restricted (about 16 and can be enlarged). The good style is not to store local references but keep only global.
- any local reference accepted from java call in JNI are released by JVM. You should release local references you created in JNI and also global references.
- do not use a large number of java object references. Each new reference gets new memory in JVM. Try to reuse refences.
I guess that is your problem.
Vitally -
Decompile applet and proxify all URL and socket connection and recompile
Hi,
Please anybody have idea for the below.
I need to decomple the applet class file to .java file and need to change all URL and Socket connection to proxify all connections from applet. and recompile the sample applet to make ready to load in browser.
Thi is to load the applet form the web server through one proxy server. In the proxy server side While loading the applet from web server that applet code need to be changed to modify the URL and connections used in that applet to change the further connection from applet through proxyserver.
Compile and decompile is not a problem that i can use javac and javap respectively.
But I want to know how to change all URL and connection in applet. is there any easy way to handle this with out changing the applet code.
can Anybody help me.
Thanks and Regards,
Shiban.Not sure how you do that:
Client <----[HTTPS]-----> Secure Gateway <------[HTTP]------->Web servers
or
Internet Explorer/Mozilla <----[HTTPS]-----> proxy <------[HTTP]-------> Google
Is the above correct?
If so than what are the proxy settings in IE/Moz, I can specify the proxy address in the
browsers but not the proxy type (SSL).
When you want to visit a page like google I gues you just type http://www.google.com in
the browsers address bar. The browser will figure out how to connect to the proxy.
Java has got the control panel in the general tabl there is a button "network settings...:"
I have it to "use browser settings" and this works for me.
All URL and URLConnections work but the sockets don't (maybe put in a bug report)
for example games.yahoo.com -> card games -> bridge -> create table
In the trace I can see:
network: Connecting http://yog70.games.scd.yahoo.com/yog/y/b/us-t1.ldict with proxy=HTTP @ myproxy/00.00.00.00:80
network: Connecting socket://yog70.games.scd.yahoo.com:11999 with proxy=DIRECT
The second one fails because port 11999 is not open (what idiot uses an unassigned
port for a profesional site is beyond me).
http://www.iana.org/assignments/port-numbers
# 11968-11999 Unassiged
Even if the port was open on the proxy you'll notice with proxy=DIRECT that
"use browser settings" does not work with socket (bug report??).
Anyway my advice is to open the java console (windows control panel or javacpl.exe in
the bin dir of java.home) and make sure it is set to "use browser settings"
Then enable a full trace:
To turn the full trace on (windows) you can start the java console, to be found here:
C:\Program Files\Java\j2re1.4...\bin\jpicpl32.exe
In the advanced tab you can fill in something for runtime parameters fill in this:
-Djavaplugin.trace=true -Djavaplugin.trace.option=basic|net|security|ext|liveconnect
if you cannot start the java console check here:
C:\Documents and Settings\userName\Application Data\Sun\Java\Deployment\deployment.properties
I think for linux this is somewhere in youruserdir/java (hidden directory)
add or change the following line:
javaplugin.jre.params=-Djavaplugin.trace\=true -Djavaplugin.trace.option\=basic|net|security|ext|liveconnect
for 1.5:
deployment.javapi.jre.1.5.0.args=-Djavaplugin.trace\=true -Djavaplugin.trace.option\=basic|net|security|ext|liveconnect
The trace is here:
C:\Documents and Settings\your user\Application Data\Sun\Java\Deployment\log\plugin...log
I think for linux this is somewhere in youruserdir/java (hidden directory)
Print out the full trace of the exception:
try{...}catch(Exception e){e.printStackTrace();}
Then visit the games.yahoo and try to create a new table playing bridge.
Inspect the trace and see if it works/why it doesn't work. -
Whats the difference b/w socketObj.getLocalPort() and socket.getPort().
Hi All!
Is there any one who could tell me whats the difference b/w socketObj.getLocalPort() and socket.getPort().
and what are their real usages.
Another thing, how is it possible to acknowledge a remoteMachine as soon as it connects to serverSocket on my machine.
Urgent Reply will be appreciatedDifference: http://java.sun.com/j2se/1.4/docs/api/java/net/Socket.html
Acknowledge: write something to the OutputStream of the Socket. -
Problem with JNI and Tomcat (and threads???)
Howdy,
Here is the issue - I would like some help on HOW to debug and fix this problem:
2 test use cases -
1)
a)User goes to Login.jsp, enters user and password
b) User submits to LoginServlet
c) login calls JNI code that connects to a powerbuilder(Yes I know this is ugly) PBNI code module (this is a .dll) that authenticates the user with the database
d) the servlet then redirects to another .jsp page
e) user then submits to LogoutServlet - also a JNI call to a powerbuilder PBNI code module
f) REPEAT STEPS a-e over a few times (inconsistent) and then the call to the JNI code hangs
2)
a) users does NOT goto Login.jsp, but rather calls LoginServlet and passes the userid and password as GET parms
b) user does NOT get redirected to a page (redirect code commented out)
c) user calls LogoutServlet
d) repeat steps a-c at will and no failure, no hanging
The only difference is that in case 1 (with JSP), there is a redirect and it afffected the JNI call by haniging inside JNI code.
In case 2 (without JSP) there is still a JNI call, but it does not hang. In addition, when it hangs and I stop Tomcat, the logs show cleanup entries that say:
Oct 19, 2004 9:17:09 AM org.apache.catalina.core.StandardWrapper unload
INFO: Waiting for 1 instance(s) to be deallocated
Oct 19, 2004 9:17:10 AM org.apache.catalina.core.StandardWrapper unload
INFO: Waiting for 1 instance(s) to be deallocated
Oct 19, 2004 9:17:11 AM org.apache.catalina.core.StandardWrapper unload
INFO: Waiting for 1 instance(s) to be deallocated
Is this a threading issue in Tomcat???
On would assume that the JNI code is not cleaning up after itself, but I don't believe this is the case,
and even if it was, why would I get the tomcat log cleanup entries above???
What do those cleanup entries imply about the state of Tomcat????hi ,
I met the same problem this morning, and searched the www.google.com in order to solve it, as a result, your article was shown on my screen. :)
Till now I have read some technical information and solved my problems. Maybe the solution be useful to you:
==============================
error message : (Environment : Tomcat 5, Windows 2003, Mysql5)
2006-3-29 11:53:48 org.apache.catalina.core.StandardWrapper unload
message: Waiting for 2 instance(s) to be deallocated
==============================
cause: the number of connection to database exceeded.another word,too many connections.
==============================
solution: close the connection when it becomes useless for your program. :)
==============================
ps. Sorry for my weak English . hehe .... -
Problem with Java Proxy and Socket Connection
Hi Gurus!!
I have developed a Java Proxy that connects via socket with a Server Socket application. This Server Socket application accepts more than one connection at the same time.
When I connect the first time from my Java Proxy, the connection is correctly established. When the first connection opened, if a try a second connection, this is not established.
I use "new Socket(SocketServer,SocketPort);" to open the connection.
I think that all time the Java Proxy is trying to open the same connection, and this is a problem.
Is there a way to indicate to the server that is a new connection and that the existing connections remain?
Anybody could help me, please?
Thanks and regards,
Manuel Míguez.Sorry!!!!i must give you more information.
The error which i have when i push the submit button is
HTTP Status 404 -
type Status report
message
descriptionThe requested resource () is not available.
GlassFish Server Open Source Edition 3.0.1
My thought is that the error is in this line
String connectionURL = "jdbc:mysql://localhost/mybooking";in mysql when i write this code then the table opens with no problems:
mysql>show databases;
mysql>usebooking;
mysql>showtables;
mysql>describe booking;Furthermore i have added in my web application the library mysql JDBC driver my-sql-connector-java-5.1.6.bin.jar
Edited by: 813355 on Nov 22, 2010 1:50 AM
Edited by: 813355 on Nov 22, 2010 2:00 AM -
Problem with JNI and Parallel Port dll
Hi. I'm doing some testes with JNI. Firs i followed the netbeans tutorial for doing a C programa that prints somthing for java.. like.. "Hello java from C".
So i tried to load a dll from my dll. Like, I have this dll to use the parallel port on windows Xp. So i created a dll to access it an comunicates eoth java.
I did everything just fine.
When I start my Java app, the first thing it does is to load this parallel port dll and configure the functions of it.
After that .. I get this error
EXCEPTION_FLT_STACK_CHECK (0xc0000092) at pc=0x0093d269, pid=2284, tid=3000
Can someone explain why ?
(Sorry if i wasn't clear enough, english is not my native language, so ask if you don't understand something.. )hi ,
I met the same problem this morning, and searched the www.google.com in order to solve it, as a result, your article was shown on my screen. :)
Till now I have read some technical information and solved my problems. Maybe the solution be useful to you:
==============================
error message : (Environment : Tomcat 5, Windows 2003, Mysql5)
2006-3-29 11:53:48 org.apache.catalina.core.StandardWrapper unload
message: Waiting for 2 instance(s) to be deallocated
==============================
cause: the number of connection to database exceeded.another word,too many connections.
==============================
solution: close the connection when it becomes useless for your program. :)
==============================
ps. Sorry for my weak English . hehe .... -
Problem with JNI and Tomcat in windows
Hello guys...
I have the following problem.
I used Tomcat 4 and I have following ApiEncriptacion class, in package com.servipag.sts;
package com.servipag.sts;
class ApiEncriptacion
public native String encripta(String texto, String ubicacionLlavePublica, String semilla);
static
System.loadLibrary("apisdark");
public native String desencripta(String texto, String ubicacionLlavePrivada);
static
System.loadLibrary("apisdark");
the LD_LIBRARY_PATH is set in following dir c:\tomcat\bice
the dll this in the following path = c:\tomcat\bice\apisdark.dll
I run Tomcat at the following way..
C:\jdk1.4\bin\java.exe -jar -Djava.library.path="c:\tomcat\bice" -Duser.dir="C:\Tomcat" "C:\Tomcat\bin\bootstrap.jar" start
but, still appear the error:
java.lang.UnsatisfiedLinkError: encripta
at com.servipag.sts.ApiEncriptacion.encripta(Native Method)
at com.servipag.sts.ServiciosServiPagImpl.rescatarFirma(ServiciosServiPagImpl.java:2143)
at com.servipag.sts.ServiciosServiPagImpl.pagarCuenta(ServiciosServiPagImpl.java:310)
at org.apache.jsp.SBCO_0005flogin_0005fbice_0005f4$jsp._jspService(SBCO_0005flogin_0005fbice_0005f4$jsp.java:265)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:107)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at org.apache.jasper.servlet.JspServlet$JspServletWrapper.service(JspServlet.java:201)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:381)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:473)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:247)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:243)
at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:190)
at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
at org.apache.catalina.valves.CertificatesValve.invoke(CertificatesValve.java:246)
at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
at org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2343)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180)
at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
at org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:170)
at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:170)
at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:468)
at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:174)
at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
at org.apache.catalina.connector.http.HttpProcessor.process(HttpProcessor.java:1012)
at org.apache.catalina.connector.http.HttpProcessor.run(HttpProcessor.java:1107)
at java.lang.Thread.run(Thread.java:536)
please help me
Luis Navarro.
ChileApiEncripatcion.h
/* DO NOT EDIT THIS FILE - it is machine generated */
#include <jni.h>
/* Header for class ApiEncriptacion */
#ifndef IncludedApiEncriptacion
#define IncludedApiEncriptacion
#ifdef __cplusplus
extern "C" {
#endif
* Class: ApiEncriptacion
* Method: encripta
* Signature: (Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;)Ljava/lang/String;
JNIEXPORT jstring JNICALL Java_ApiEncriptacion_encripta
(JNIEnv *, jobject, jstring, jstring, jstring);
* Class: ApiEncriptacion
* Method: desencripta
* Signature: (Ljava/lang/String;Ljava/lang/String;)Ljava/lang/String;
JNIEXPORT jstring JNICALL Java_ApiEncriptacion_desencripta
(JNIEnv *, jobject, jstring, jstring);
#ifdef __cplusplus
#endif
#endif
ApiEncriptacion.c
#include "jni.h"
#include <stdio.h>
#include "files.h"
#include "hex.h"
#include "rsa.h"
#include "randpool.h"
USING_NAMESPACE(CryptoPP)
USING_NAMESPACE(std)
void GenerateRSAKey(unsigned int keyLength, const char privFilename, const char pubFilename, const char *seed);
char RSAEncryptString(const char pubFilename, const char seed, const char message);
char RSADecryptString(const char privFilename, const char *ciphertext);
JNIEXPORT jstring JNICALL
Java_ApiEncriptacion_encripta(JNIEnv *env, jobject obj, jstring texto, jstring ubicacionLlavePublica, jstring semilla)
try
char *ciphertext = RSAEncryptString(ubicacionLlavePublica, semilla, texto);
delete [] ciphertext;
return(ciphertext);
catch(CryptoPP::Exception &e)
return ("");
catch(std::exception &e)
return ("");
catch(...)
return ("");
JNIEXPORT jstring JNICALL
Java_ApiEncriptacion_desencripta(JNIEnv *env, jobject obj, jstring texto, jstring ubicacionLlavePrivada)
try
char *decrypted = RSADecryptString(ubicacionLlavePrivada, texto);
return(decrypted);
catch(CryptoPP::Exception &e)
return ("");
catch(std::exception &e)
return ("");
catch(...)
return ("");
int main()
return(0);
void GenerateRSAKey(unsigned int keyLength, const char privFilename, const char pubFilename, const char *seed)
RandomPool randPool;
randPool.Put((byte *)seed, strlen(seed));
RSAES_OAEP_SHA_Decryptor priv(randPool, keyLength);
HexEncoder privFile(new FileSink(privFilename));
priv.DEREncode(privFile);
privFile.MessageEnd();
RSAES_OAEP_SHA_Encryptor pub(priv);
HexEncoder pubFile(new FileSink(pubFilename));
pub.DEREncode(pubFile);
pubFile.MessageEnd();
char RSAEncryptString(const char pubFilename, const char seed, const char message)
FileSource pubFile(pubFilename, true, new HexDecoder);
RSAES_OAEP_SHA_Encryptor pub(pubFile);
if (strlen(message) > pub.MaxPlainTextLength())
cerr << "message too long for this key\n";
abort();
RandomPool randPool;
randPool.Put((byte *)seed, strlen(seed));
char outstr = new char[2pub.CipherTextLength()+1];
pub.Encrypt(randPool, (byte *)message, strlen(message), (byte *)outstr);
HexEncoder hexEncoder;
hexEncoder.Put((byte *)outstr, pub.CipherTextLength());
hexEncoder.MessageEnd();
hexEncoder.Get((byte *)outstr, 2*pub.CipherTextLength());
outstr[2*pub.CipherTextLength()] = 0;
return outstr;
char RSADecryptString(const char privFilename, const char *ciphertext)
FileSource privFile(privFilename, true, new HexDecoder);
RSAES_OAEP_SHA_Decryptor priv(privFile);
HexDecoder hexDecoder;
hexDecoder.Put((byte *)ciphertext, strlen(ciphertext));
hexDecoder.MessageEnd();
SecByteBlock buf(priv.CipherTextLength());
hexDecoder.Get(buf, priv.CipherTextLength());
char *outstr = new char[priv.MaxPlainTextLength()+1];
unsigned messageLength = priv.Decrypt(buf, (byte *)outstr);
outstr[messageLength] = 0;
return outstr; -
JNI and Tomcat running on Linux
Hi all!
I have a small problem with calling a native library from my Tomcat running on a linux.
The code is simple enough
System.loadLibrary(myLibrary);I know that when libmyLibrary.so isn't in the java.library.path I get an error at this line. When it is in the path it goes past this line with out problems but on the next line
myFunction(); that is a function within myLibrary i get something like
java.lang.UnsatisfiedLinkError: myFunction()The thing is. This exact code when either executed in a standalone java application or from a Tomcat running on windows works with out problem. Tomcat on linux doesn't.
myLibrary uses other libraries on a different path and my guess is that tomcat for some reason won't allow access to those. The security manager however doesn't give me any errors, nor does tomcat itself other than the UnsatisfiedLinkError.
Anyone running Tomcat on linux and using native libraries or perhaps just knows alot about this?
Please help. Thanks!Are you sure you are not running into a class loader issue? Does this occur the very first LoadLibrary call or after the first successfull call?
It could be that your JNI or bridge has already been loaded by another class loader in the tomcat class loader hierarchy and this would result in the UnsatisfiedLinkError.
Check out: http://www.onjava.com/pub/a/onjava/2004/06/30/classloader2.html
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