System Programming

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Kernel and system programming is the process of creating the software necessary for a computer or device to function and operate other programs. Some operating systems (such as Microsoft Windows) are proprietary, but others, such as the various Linux distributions, are open source.

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object aid

when i try to add object aid uml plugin worked on one laptop

other laptop
when i gave the name

Name as Object Aid UML Explorer
Location http://objectaid.com/update/current

from eclipse-->help->install new softwares


getting below error

Unable to read repository at http://objectaid.com/update/current/content.xml.
Unable to read repository at http://objectaid.com/update/current/content.xml.
Malformed reply from SOCKS server


please advise
0
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eclipse keplan through help market place i installed glassfih tools

i also downloaded the glass fish 5 from
https://javaee.github.io/glassfish/download

when go to file new server add glassfish locations says only 4 and 3.1 versions of glassfish supported
i tried to search internet to get glasfish 4 or 4.1 etc but could not find

can you please advise where i have to go to get it

please advise
0
Hi All,

I am looking for a free open source POS system with no licensing which i can customise myself and use.

Anyone has any recommendations?
0
Hi Experts,
I have this question after solving the following..
https://www.experts-exchange.com/questions/29108803/Script-to-read-all-files-of-specific-folder.html#acceptAnswerByMember
In that question I got a script how to count all records of files in one folder.
However now I need to know from that count how many are under one specific category.
Therefore I thought the best way would be to concatenate all files into one, just ignoring the headers.
And from there I will link to MS Access and get the results from a query.
Anyone has either a script for that or another way to accomplish the task?
Thanks in advance.
0
what are differences between

stateless
stateful
singleton
mdb enterprise java beans.

when to use which one

any practical examples on them to see differences.

any links, resources, videos?
please advise
0
tail -f logfile.log


what is the meaning of above command.

i see logs rolling too fast.

is there is a way i can slow it down to see clearly slowly

any god tips, links, resources on how to debug production logs efficiently just using putty without any fancy costly tools?

please advise
0
what is the best tool to do profiling for c++ multi threaded server daemon on Linux?

Complied program with -pg and the tried with gprof/gmon.out. Couldn't find call graph as per functions mentioned in my program. It has shown all low level api's call graph like string internals, memory allocations..etc.

Can someone suggest how to get call graph from gmon.out for multi threaded server daemon.

Any other tool(s)?
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hi,



I am not clear on producer extends vs consumer super​ for generics



usually in ejb jms mdb world

if some one says consumer means who consumes messages which producer puts in queue right



But here concept seems reverse

producer extends

can read but cannot add
 consumer super​​
can add but cannot read to list?


please advise
0
why String is an Object but Collection<String> is not a Collection<Object> with respect to unbounded wildcards of java generics

Please advise
0
Hi Experts,
Looking for a script that gives me all large files created on the server in the past 10 days..
should return file name, date created, size of file, user created.
Thanks in advance.
0
Cloud Class® Course: MCSA MCSE Windows Server 2012
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Cloud Class® Course: MCSA MCSE Windows Server 2012

This course teaches how to install and configure Windows Server 2012 R2.  It is the first step on your path to becoming a Microsoft Certified Solutions Expert (MCSE).

while executing spring boot soap example keep getting error like below

Description:

The Tomcat connector configured to listen on port 8081 failed to start. The port may already be in use or the connector may be misconfigured.

Action:

Verify the connector's configuration, identify and stop any process that's listening on port 8081, or configure this application to listen on another port.


I tried 8080 as well in application.properties even that did not work


how to find what ports are free on my windows 10 laptop to use that ?

please advise
0
Eclipse has tabs File,Edit,Navigate,Search, Project etc at top

Under project there is Clean and 'Build All' options to clean and build 10 different projects(project_1, project_2....project_10) i have at one stroke

but after doing that i get error as below for project_10
Error:Counld not fine or load main class com.xyz.zbc.drivertesting.Sample.java


if i do maven install on project _10 then above error is resolved but later stage i get

javax.naming.NoInitialContextException: Cannot instantiate class: weblogic.jndi.WLInitialContextFactory [Root exception is java.lang.ClassNotFoundException: weblogic.jndi.WLInitialContextFactory]


how maven install or maven build is different from Eclipse-->Project--->Build All
0
Hi,
I have a requirement for an excel sheet to be formatted from a flat structure to a stacked structure. I'll try to explain:
In the flat structure has a number of basic columns, some of these columns repeat multiple times ('Transaction1', 'Transaction2', 'Transaction3'). some of the items will not have all transaction data, therefore some of those columns may be blank for a given item.

Example - https://imgur.com/B3h4Iir

I need to take this data structure and transform it in another sheet/workbook so it goes like this. The transaction is a single column with the transaction1,2,3 data repeating as row beneath the item, all other columns will remain blank. The next item will begin on the next available blank row.

Example - https://imgur.com/x8f2c4T

Thanks,
0
Hi Experts,
I got an invitation from someone to upload something to their google drive, however when I click on new button, the upload options are disabled and a message appears stating "you are working offline, and some functions are not avail.."
What is the cause and how can I change it?
Thanks in advance
0
checked exception



public class ThrowEx {

      public static void main(String[] args) {
            
            try{
            throw new Exception("file not there");
            }
            catch(Exception e){
                  
            }

      }

}



why i ned to have try catch for above example.

If i skip i am getting compilation error


https://www.google.com/search?q=java+exception+checked&safe=active&rlz=1C1GGRV_enUS765US765&source=lnms&tbm=isch&sa=X&ved=0ahUKEwi_7qLdjLjaAhWDylMKHfzxDigQ_AUICigB&biw=1280&bih=615#imgdii=dKyeLgDJI-TIrM:&imgrc=Xm7qPed58fGj2M:

Exception could be Run time(unchecked which does not need explicit try catch like indexoutofbound, arthematic) , unchecked(which needs explicit try catch like IOException)
as well right?

please advise
0
Class Parent{
start(){}
}
Class Child extends Parent{
start(){
//override in child
}
processChildMethod(){//not overriden by parent method
}

}

Parent p= new Child();


Child c=(Child)p// why we do like this

c.processChildMethod();

my quwstion is  why we downcase like this

Child c=(Child)p


Child ch=new Child();
ch.processChildMethod()
above is enough right?
please advisse
0
which approach is better as given below and why. please advise


Convert with Plain Java
Let’s start with a simple example using Java to do the conversion – using an intermediary byte array:


@Test
public void givenUsingPlainJava_whenConvertingStringToInputStream_thenCorrect()
  throws IOException {
    String initialString = "text";
    InputStream targetStream = new ByteArrayInputStream(initialString.getBytes());
}
Note that the getBytes() method encodes this String using the platform’s default charset so to avoid undesirable behavior you can use getBytes(Charset charset) and control the encoding process.


 Convert with Commons IO
Finally, the Apache Commons IO library provides an excellent direct solution:


@Test
public void givenUsingCommonsIO_whenConvertingStringToInputStream_thenCorrect()
  throws IOException {
    String initialString = "text";
    InputStream targetStream = IOUtils.toInputStream(initialString);
}
0
How to use c4.5 classifier in android studio to process the  accelerometer and and gyroscope  sensor data from phone.
0
WhoisRIR.java
public enum WhoisRIR {
    ARIN("whois.arin.net"),
    RIPE("whois.ripe.net"),
    APNIC("whois.apnic.net"),
    AFRINIC("whois.afrinic.net"),
    LACNIC("whois.lacnic.net"),
    JPNIC("whois.nic.ad.jp"),
    KRNIC("whois.nic.or.kr"),
    CNNIC("ipwhois.cnnic.cn"),
    UNKNOWN("");

    private String url;

    WhoisRIR(String url) {
        this.url = url;
    }

    public String url() {
        return url;
    }
}
Copy
Test.java
public class Test {

    public static void main(String[] args) {

		//whois.arin.net
        System.out.println(WhoisRIR.ARIN.url());

    }

}

Open in new window


going through above code from below link

https://www.mkyong.com/java/java-enum-example/

i was not clear how i got output as below

whois.arin.net


is enum like a class?
how enum different from java class?

when we use enum

not clear on below as well
Enum + Method + Some logic
Operation.java
public enum Operation {
    PLUS,
    MINUS,
    TIMES,
    DIVIDE;

    double calculate(double x, double y) {
        switch (this) {
            case PLUS:
                return x + y;
            case MINUS:
                return x - y;
            case TIMES:
                return x * y;
            case DIVIDE:
                return x / y;
            default:
                throw new AssertionError("Unknown operations " + this);
        }
    }

}
Copy
Test.java
public class Test {

    public static void main(String[] args) {

        double result = Operation.PLUS.calculate(1, 2);
        System.out.println(result); //3.0

    }

}
Copy
4. How to use Enum
4.1 To loop a Enum object.

public class Test {

    public static void main(String[] args) {

        for (UserStatus status : UserStatus.values()) {
            System.out.println(status);
        }

    }

}
Copy
Output

PENDING
ACTIVE
INACTIVE
DELETED

Open in new window

please advise
0
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Dual pipe producer/consumer blocked by read.

The issue is in the producer:
        read(consumer_to_producer[0], &cnt, sizeof(cnt));
        read(consumer_to_producer[0], shared_arr, sizeof(shared_arr));

Open in new window

prevents the producer from working because the consumer has yet to write anything, how can I avoid this?


#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#define SIZE 10

int shared_arr[SIZE];
int cnt = 0, in = 0, out = 0;
int consumer_to_producer[2], producer_to_consumer[2];

void consumer();
void producer();

int main() {
    pipe(consumer_to_producer); // consumer to producer
    pipe(producer_to_consumer); // producer to consumer

    if (fork() == 0) {
        /* child process */
        consumer();
    } else {
        /* parent process */
        producer();
        sleep(3);
    }

    exit(0);
}

void consumer() {
    /* consumer process */
    close(producer_to_consumer[1]); // Close write end, we don't need it
    close(consumer_to_producer[0]); // This fcn doesn't need read end
    while (1) { 
        /* if buffer is full, consume it */
        // read in cnt from producer so we can check if it's full
        read(producer_to_consumer[0], &cnt, sizeof(cnt));

        if (cnt == SIZE) { /* If full, consume */
            read(producer_to_consumer[0], shared_arr, sizeof(shared_arr));
            printf("I am consuming\t%d\t%d\n", shared_arr[in], out);
            out = (out + 1) % SIZE;
            cnt--;
        } 

        

Open in new window

0
In VBA while accessing Reference, error comes 'Error accessing the system Registry'

Your solution at the following webpage not found.
http://support.microsoft.com/default.aspx?scid=kb;en-us;269383

Please helo
0
I am writing a software removal program, and want to uninstall a context menu driver. Just unregistering the driver while Windows File Explorer is open causes a Windows error "Program has stopped working" when trying to unregister the dll. Closing file explorer first and then running the program works fine.

Here is the unregister code I am using now:

HINSTANCE hLib = LoadLibraryW(szDllPath);

    if (hLib == NULL)
    {
		DWORD dwErrorCode = GetLastError();
		szError.Format(_T("\nWindows could not load library %s due to %s"),szDllName,getLastWinError(dwErrorCode));
		return false;            
    }

    typedef HRESULT (CALLBACK *HCRET)(void);
    HCRET lpfnDllRegisterServer;

    // Find the entry point
    lpfnDllRegisterServer = (HCRET)GetProcAddress(hLib, "DllUnregisterServer");



    if (lpfnDllRegisterServer == NULL)
    {
		szError = NEWLINE;
		szError = ERR_PROCEDURE_ADDRESS;
		return false;            
    }

    // Call the function by function pointer..
    if (FAILED((*lpfnDllRegisterServer)()))            
    {   
		szError.Format(_T("\nWindows could not unregister context menu driver %s!"),szDllName);
		return false;            
    }

    FreeLibrary(hLib);

Open in new window


What is the best way to go about this to avoid this Windows error?
0
What are the advantages and disadvantages of pipes ,fifo's,threads,sockets,shared memory,message queue's.And which of them i s faster?
0
any free tools like xpmspy which is free for generating sample xmls from XSDs and to work with XSLT etc.

I head XMLEdit but i did not see any direct link to download though?

Please advise
0
when i deployed war to the webapps location of tomcat getting errors
http://localhost:8080/security-form-based/protected/index.jsp

HTTP Status 404 – Not Found
Type Status Report

Message /security-form-based/protected/index.jsp

Description The origin server did not find a current representation for the target resource or is not willing to disclose that one exists.

please advise



tried below link

https://www.concretepage.com/java-ee/jsp-servlet/form-based-authentication-in-jsp-using-tomcat

i am getting below error

ud_mdb_activemq\JSPLoginDemo>gradle clean build
'gradle' is not recognized as an internal or external command,
operable program or batch file.

please advise
0

System Programming

40K

Solutions

19K

Contributors

Kernel and system programming is the process of creating the software necessary for a computer or device to function and operate other programs. Some operating systems (such as Microsoft Windows) are proprietary, but others, such as the various Linux distributions, are open source.