Append stream object to existing file

Hello, I'm trying to append a live stream to an existing file, but I cant figure out how to open the existing file and then append the live stream. This is server side as well.
I know I need to open the existing file using stream = stream.get("file"). but I don't understand how to associate stream with the live stream coming in.
PLEASE HELP~!!!

This is what I have now, and it still overwrites :*(
application.onPublish = function (p_c, p_stream)
    //check for the file helpers
    filePath = new File("/streams/_definst_/");
    fileName = p_stream.name + ".flv";
    fileTest = filePath.fileName;
    if (fileTest.exists == false){
        p_stream.record();
    } else {
        mynewstream = Stream.get(p_stream.name);
        mynewstream.onStatus = function(info){
             trace(info.code);
        mynewstream.record("append");
        mynewstream.play(p_stream.name ,-1,-1,true);   //where livestream in name of stream getting published.

Similar Messages

How to append contents to an existing file contents at the end of file?

Hi all
I am Kiran, working with LV8.0 FDS
I find difficulty while trying to add new file contents(some messages) to an existing file at the end /begining of a file.
Whenever i try to do that,it is replacing the previous contents,but i dont need that. i want the contents to be appended.
Plz suggest me.
thanks & regards
kiran

Hi Kiran,
yes, I can attach a screenshot
(open file, set file position to end, write text, close file)
Message Edited by GerdW on 08-16-2007 03:19 PM
Best regards,
GerdW
CLAD, using 2009SP1 + LV2011SP1 + LV2014SP1 on WinXP+Win7+cRIO
Kudos are welcome
Attachments:
append.png ‏2 KB

Append data to a existing file thru ALSB Service

Hi,
I want to write/append message data to a file before and after I invoke a Business Service.
I have created a Business Service with Service Type as Messaging Service and the protocol as FILE. I notice that everytime I call the Business Services a new text file is created. Is there a way I can append messages to the same file.
The workaround I thought of is to write a Java Class to write/append data to a file and invoke this as a Java Callout. Is this a feasible/good solution.
If anybody has any ideas of implementing this, please help.
Thank you.

This feature is not supported by ALSB
You are correct, your best bet is to write some code in a Java callout to implement your expected behavior.
Gregory Haardt
ALSB Prg. Manager
[email protected]

How to append binary data to existing file in OSB

Hi,
I have an OSB project that I need for it to append binary data via ftp. Here's my current flow:
MFL binary output --> Replace $body with mfl binary output --> Publish to action (Business service that's configured to ftp binary data).
However, when the data is ftp'ed the following error is thrown:
URI = ftp://xxx:21/opt/home/zzz/logs
Request metadata =
    <xml-fragment>
      <tran:headers xsi:type="ftp:FtpRequestHeaders" xmlns:ftp="http://www.bea.com/wli/sb/transports/ftp" xmlns:tran="http://www.bea.com/wli/sb/transports" xmlns:xsi="h
ttp://www.w3.org/2001/XMLSchema-instance">
        <ftp:fileName>11802_insert_oh_xfrmr.eai_data</ftp:fileName>
      </tran:headers>
      <tran:encoding xmlns:tran="http://www.bea.com/wli/sb/transports">utf-8</tran:encoding>
      <ftp:isFilePath xmlns:ftp="http://www.bea.com/wli/sb/transports/ftp">false</ftp:isFilePath>
    </xml-fragment>
Payload =
19266787^CLLL^C711791^CLLL^C^C1178213^CSingle Phase(1)^C63185066204^CA^CConstructed^C358880 NW 4 DR LK MONTAZA^C120/240^C09361^CN/A^CProposed Remove^CAerial^C45718100^C
Unknown^C^CNo^CNormal Closed^CClamp^CA^C1^C2-Cover^C19266796^CNo^CNo^C15^C^CYes^CYes^CYes^C13200Y/7620 X 22860Y/13200^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C
^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C19266641^Coh_fuse_switch^C63086930001^C4^CN31^CDD0613^C22.9^C63376474601^C8129580^CFalse^C4^COke
echobee^C43^C0^Cdefault^CYes^C
>
####<Nov 6, 2013 2:28:23 PM EST> <Error> <WliSbTransports> <goxsd1604> <osb_server1> <[ACTIVE] ExecuteThread: '3' for queue: 'weblogic.kernel.Default (self-tuning)'> <<
anonymous>> <BEA1-4B688443B66FA09FFE75> <d2b4601b2fffd9b7:6b9f2297:1422a857ee8:-8000-000000000000171b> <1383766103889> <BEA-381105> <Error occured for the service endpo
int: com.bea.wli.sb.transports.TransportException: Unable to open data connection. Message is Received error response (553) from FTP server [mpsd1] IP [10.111.19.32] po
rt [21] status [connected] upon executing command [stor opt/home/zzz/logs/11802_insert_oh_xfrmr.eai_data.a]
com.bea.wli.sb.transports.TransportException: Unable to open data connection. Message is Received error response (553) from FTP server [mpsd1] IP [10.111.19.32] port [2
1] status [connected] upon executing command [stor opt/home/icanadm/logs/11802_insert_oh_xfrmr.eai_data.a]
        at com.bea.wli.sb.transports.ftp.connector.FTPTransportProvider.sendMessage(FTPTransportProvider.java:422)
From what I understand the error code 553 represents a bad file name. The file name that I'm supplying is 11802_insert_oh_xfrmr.eai_data but it appears that the name is changed to 11802_insert_oh_xfrmr.eai_data.a . So I did the obvious and changed the file several different ways (without the .eai_data extension, removed the numbers from the file name) but still no luck.
Any suggestions?
Thanks,
Yusuf

Thanks Eric.
I'm using the JCA FTP adapter instead and noticed it's appending the test generated data supplied by the OSB test console.
However, how can I ensure that the MFL output that I need to append will be placed on a new line?
Also, how should I map/assign the MFL binary output to the opaqueElement type base64Binary defined in the WSDL file below?
Once again here's a sample payload that I need to ensure will be presented on a new line:
19266787^CLLL^C711791^CLLL^C^C1178213^CSingle Phase(1)^C63185066204^CA^CConstructed^C358880 NW 4 DR LK MONTAZA^C120/240^C09361^CN/A^CProposed Remove^CAerial^C45718100^C
Unknown^C^CNo^CNormal Closed^CClamp^CA^C1^C2-Cover^C19266796^CNo^CNo^C15^C^CYes^CYes^CYes^C13200Y/7620 X 22860Y/13200^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C
^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C19266641^Coh_fuse_switch^C63086930001^C4^CN31^CDD0613^C22.9^C63376474601^C8129580^CFalse^C4^COke
echobee^C43^C0^Cdefault^CYes
Here's the WSDL file that gets generated for the FTP adapter:
<wsdl:definitions
     name="PutGenericDevice"
     targetNamespace="http://xmlns.oracle.com/pcbpel/adapter/ftp/AMS/Project1/PutGenericDevice"
     xmlns:jca="http://xmlns.oracle.com/pcbpel/wsdl/jca/"
     xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/"
     xmlns:tns="http://xmlns.oracle.com/pcbpel/adapter/ftp/AMS/Project1/PutGenericDevice"
     xmlns:opaque="http://xmlns.oracle.com/pcbpel/adapter/opaque/"
     xmlns:plt="http://schemas.xmlsoap.org/ws/2003/05/partner-link/"
    >
<plt:partnerLinkType name="Put_plt" >
    <plt:role name="Put_role" >
      <plt:portType name="tns:Put_ptt" />
    </plt:role>
</plt:partnerLinkType>
    <wsdl:types>
    <schema targetNamespace="http://xmlns.oracle.com/pcbpel/adapter/opaque/"
            xmlns="http://www.w3.org/2001/XMLSchema" >
      <element name="opaqueElement" type="base64Binary"/>
    </schema>
    </wsdl:types>
    <wsdl:message name="Put_msg">
        <wsdl:part name="opaque" element="opaque:opaqueElement"/>
    </wsdl:message>
    <wsdl:portType name="Put_ptt">
        <wsdl:operation name="Put">
            <wsdl:input message="tns:Put_msg"/>
        </wsdl:operation>
    </wsdl:portType>
</wsdl:definitions>
Here's the JCA details:
<adapter-config name="PutGenericDevice" adapter="FTP Adapter" wsdlLocation="PutGenericDevice.wsdl" xmlns="http://platform.integration.oracle/blocks/adapter/fw/metadata">
<connection-factory location="eis/ftp/DssPut"/>
<endpoint-interaction portType="Put_ptt" operation="Put">
    <interaction-spec className="oracle.tip.adapter.ftp.outbound.FTPInteractionSpec">
      <property name="PhysicalDirectory" value="/opt/eai/ofmw/Oracle/Middleware_R7/logs"/>
      <property name="FileType" value="binary"/>
      <property name="Append" value="true"/>
      <property name="FileNamingConvention" value="dummy.txt"/>
    </interaction-spec>
</endpoint-interaction>
</adapter-config>
Thanks,
Yusuf

Trouble importing objects into existing file

I have Captivate 4 and would like to import slides/objects from file 1 to file 2.
Everytime I do this, captivate crashes and says that it has encountered an unexpected error. It is driving me crazy,
especially since it's not like I can copy and paste in the program. Or can I? Please help.

Fortunately I haven't had a corrupted file or project for some time now. I put it down to never working on project files over a network and never pasting in content from other people's projects.
But the way I used to track down corrupt elements or slides was to Save As to get a copy of my problem project and then hide or delete half the slides in the project to see if that removed the problem. If not, I try hiding or deleting the other half of the project to see if that worked. If you find the half that has the problem, then delete half of that half and repeat the process. Eventually, by a process of elimination, you get down to where the issue is. Then you can go back to your main project and fix it. Hopefully it's just a matter of recreating a slide or two.

Appending new TextLine into existing file

I tried to add new text lines into an existing txt file. The problem is my method add new Strings on the same line (to see it you need to open the output file with notepad).
The method invoked is:
public static void addText( String arg0, String path ) {
          long pos;
          try {
               raf = new RandomAccessFile( path , "rw" );
               pos = raf.length();
               raf.seek( pos ); //mi sposto alla fine del file
               raf.writeBytes( "\n" ); // new line
               raf.writeBytes(arg0); //
               raf.close();
          } catch (FileNotFoundException e) {
               // TODO Auto-generated catch block
               e.printStackTrace();
          } catch (IOException e) {
               // TODO Auto-generated catch block
               e.printStackTrace();
     }

To make your app system-independent use:
String lineSeparator = System.getProperty("line.separator");as line separator
[]

How to write data to existing file using spool command?

Hi,
I am calling a stored procedure from a shell script. This stored procedure is having a CLOB object as an OUT parameter. How to write the data in CLOB object a existing file which is there in my client system. Below is the shell and sql scripts.
Shell script
( echo "hello" ) > /root/file.txt
sqlplus -s $user/$pass@$tns @/root/proc.sql /root/file.txt << EOF
EOFSQL script
set pages 0
set trimspool off
set serveroutput off
set feedback off
set term off
set echo off
variable out CLOB
define file='&1'
begin
pack.proc(:out);
end;
spool &file
select :out from dual;
spool offThis code writes contents of the OUT variable to file.txt, but my existing data ('hello') is lost. Please help me.
I figured the it...Use append in the spool command... :)
Edited by: Balaji on Jul 19, 2012 8:55 PM

>
Hi Balaji
I figured the it...Use append in the spool command... :Please mark the thread as answered as per the FAQ.
Paul...

Appending XML data to a file using file adaptor

Hi,
I am trying to append data to a file using file adaptor in XML format. (Objective is to store data as XML message in the file). I understand it is possible to append data to an existing file by making appropriate changes in WSDL manually. However, my issue is every time the XML data is appended to a file even the XML header message is also getting appended. As a result the file data does not adhere to defined schema structure anymore.
Is there a way to save XML data in a file in append mode ?
Thanks, Riz

I am having the same issue as well, which makes the output XML an invalid one. I have an XSD that has a hierarchy of elements. whenever I am wiriting the child elements the header message & the name space is also getting written. For example
<?xml version="1.0" ?><Parent xmlns="http://testSchema.com/outputSchema">
<StartDate>01/01/2001</StartDate>
<EndDate>01/30/2001</EndDate>
<Child/>
</Parent>
<?xml version="1.0" ?><Child xmlns:ns1="http://testSchema.com/outputSchema">
<ns1:Id>20012981</ns1:Id>
<ns1:Value/>
<ns1:Date>01/15/2001</ns1:Date>
</Child>
<?xml version="1.0" ?><Child xmlns:ns1="http://testSchema.com/outputSchema">
<ns1:Id>20012981</ns1:Id>
<ns1:Value/>
<ns1:Date>01/15/2001</ns1:Date>
</Child>
I am using a onefile adapter partnerlink to write the parent & an another one for writing the child element, since the child elements will repeat more than once. One other way to fix this issue is write the data using java embedded activity, but that would need a lot of boiler plate code, for writing/reading/appending the same file & for handling all those IOexceptions & buffer IN/outs. I am curious if someone had the same issue & how they resolved it.

How to read data from multiple files and append in columns in one file

Hi Guys,
I have a problem in appending data from files in different columns. I have attachement has file A and B which I am reading and not able to get data as in file Result.txt. Please comment on how can I do this
Solved!
Go to Solution.
Attachments:
Write to file.vi ‏13 KB
A.txt.txt ‏1 KB
B.txt.txt ‏1 KB

You cannot append columns to an existing file. Since the data is arrange line-by-line as one long linear string in the file, you can only append rows. A new row needs to be interlaced into the original file, shifting everything else. If you want to append rows, you need to build the entire output structure in memory and then write all at once.
(I also don't think you need to set the file positions, it will be remembered from the last write operation.)
Unless the files are gigantic, here's what I would do:
(Also note that some of your rows have an extra tab at the end. If this is normal, you need a little bit more code to strop out empty columns. I include cleaned up files in the attachment. I also would not call them A.txt.txt etc. A plain A.txt is probably sufficient.)
EDIT: It seems Dennis's solution is similar )
LabVIEW Champion . Do more with less code and in less time .
Attachments:
Write to fileMOD.zip ‏6 KB
MergeColumns.png ‏6 KB

Appending objects in text file and searching.......

I have been trieng to implement simple search operation on the class objects stored in the text file. but when i try to append new objects in the same file and search for the same; java.io.StreamCorruptedException is thrown. wat the problem is, that wen i append to the text file; it stores some header information before the actual object is stored and on the deserialization, this header information is causing the exception. the same header information is stored every time, i append to the file. anybody knws hw to get past it??? my code is as given below:
package coding;
import java.io.BufferedReader;
import java.io.EOFException;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.PrintWriter;
import java.io.Serializable;
     class Employee implements Serializable{
          private static final long serialVersionUID = 1L;
          String name;
          int id;
          public int getId() {
               return id;
          public void setId(int id) {
               this.id = id;
          public String getName() {
               return name;
          public void setName(String name) {
               this.name = name;
          public Employee(String name, int id) {
               this.name = name;
               this.id = id;
     public class FileSearch{
     public static void main(String[] args) throws IOException
          /*Entering the records into the file*/
          Employee ob = null;
          File file=new File("c:\\abc.txt");
          InputStreamReader isr=new InputStreamReader(System.in);
          BufferedReader stdin=new BufferedReader(isr);
          char fileExist='y';
          if(file.exists())
               System.out.println("File already exists!!!");
               System.out.println("Append New Records(press y) Or Search Existing File(press any other button)?:");
               String strTemp=stdin.readLine();
               fileExist=strTemp.charAt(0);
          else
               System.out.println("File doesnt exist; creating new file......");
          if(fileExist=='y')
               FileOutputStream fos=new FileOutputStream(file,true);
               ObjectOutputStream oos=new ObjectOutputStream(fos);
               char choice='y';
               System.out.println("Enter records:");
               while(choice=='y')
                    System.out.println("enter id:");
                    String id_s=stdin.readLine();
                    int id=Integer.parseInt(id_s);
                    System.out.println("enter name:");
                    String name=stdin.readLine();
                    ob=new Employee(name,id);
                    try
                         oos.writeObject(ob);
                         //count++;
                         oos.flush();
                    catch(Exception e)
                         e.printStackTrace();
                    System.out.println("Enter more records?(y/n)");
                    String str1=stdin.readLine();
                    choice=str1.charAt(0);
               oos.close();
          /*Searching for the record*/
          System.out.println("Enter Record id to be searched:");
          String idSearchStr=stdin.readLine();
          int idSearch=Integer.parseInt(idSearchStr);
          try
               FileInputStream fis=new FileInputStream(
                         file);
               ObjectInputStream ois=new ObjectInputStream(fis);
               int flag=1;
               FileReader fr=new FileReader(file);
               int c=fr.read();
               for(int i=0;i<c;i++)
                    Object ff=ois.readObject();
                    Employee filesearch=(Employee)ff;
                    if(filesearch.id==idSearch)
                         flag=0;
                         break;
               ois.close();
               if(flag==1)
                    System.out.println("Search Unsuccessful");
               else
                    System.out.println("Search Successful");
          catch(Exception e)
               e.printStackTrace();
}

966676 wrote:
All what I need to elect by who this word repeated. But I don't know really how to make It, maybe LinkedListYou should choose the simplest type fullfilling your needs. In this case I'd go for <tt>HashSet</tt> or <tt>ArrayList</tt>.
or I dont know, someone could help me?You need to introduce a variable to store the actual name which must be resetted if an empty line is found and then gets assigned the verry next word in the file.
bye
TPD

How to append Objects in a file.

i have the following sample code ,
its not read data properly and throws Stream Corrupted Exception in the appended record. ( at Last statement of try block ).
Thanks,
import java.io.*;
public class IOError {
public static void main(String[] args) {
try {
ObjectOutputStream oos = new ObjectOutputStream(
new FileOutputStream("data.dat"));
oos.writeObject(new String("string 1"));
oos.writeObject(new String("string 2"));
oos.flush();
oos.close();
ObjectInputStream ois = new ObjectInputStream(new FileInputStream("data.dat"));
System.out.println("----- Round 1 Starts ---------");
System.out.println((String) ois.readObject());
System.out.println((String) ois.readObject());
ois.close();
ObjectOutputStream oos2 = new ObjectOutputStream(
new FileOutputStream("data.dat",true)); // Appending Data
oos2.writeObject(new String("string 3"));
oos2.flush();
oos2.close();
ObjectInputStream ois2 = new ObjectInputStream(new FileInputStream("data.dat"));
System.out.println("----- Round 2 Starts ---------");
System.out.println((String) ois2.readObject());
System.out.println((String) ois2.readObject());
System.out.println((String) ois2.readObject()); // Stream Corrupted Exception
catch(Exception e) {
System.out.println(e);

Nasty. When you open an ObjectOutputStream, it will write a few initializing bytes, so if you really want to append objects to a file, then after you read the first two strings, you need to create a new ObjectInputStream that will read those bytes.
You could write an object indicating that now you are done with this ObjectOutputStream, so when you read the file and read this object, you know you have to create a new ObjectInputStream.
oos.writeObject(new String("string 1"));
oos.writeObject(new String("string 2"));
oos.writeObject(null); // null could be used if you know you won't write any other null's in your code.
//... append
oos.writeObject(new String("string 3"));
oos.writeObject(null);
// read:
FileInputStream fis = new FileInputStream("data.dat");
ObjectInputStream ois2 = new ObjectInputStream(fis);
String s;
while ((s = (String)ois2.readObject()) != null) {
System.out.println(s);
ois2 = new ObjectInputStream(fis);
while ((s = (String)ois2.readObject()) != null) {
System.out.println(s);

Appending Objects to a File using serialization

hi,
I was wondering if I can append objects in a single file. For example, suppose there are 2 .java files. 1st file creates the Serialized file caleed sl.dat, opens it, writes the object, close it down.
The 2nd file nw open that same file, sl.dat, in append mode, writes one more object and close it down.
next I want to read each object of the file. Will it work in this fashion?
I found a quite interesting discussion here. but it says that it is not possible.. is that true?
Any clue? Is there any other mean to achieve this?

arin wrote:
kajbj wrote:
I've done it by subclassing ObjectOutputStream. I could then add a constructor that took an argument that indicated if a header should be written or not.Can you explain what I need to done here... I have a class which extends ObjectOutputStream but what to do after that? What do u mean by header in the constructor?? Please help meYou do know that you have the source code for the class if you have a JDK? The source for ObjectOutputStream is in the src.zip.
The normal constructor calls writeStreamHeader, and that is the problem if you are going to append data since you don't want to get the stream header more than once. Create a constructor that takes a boolean as argument, and only calls writeStreamHeader if the boolean is true.
Kaj

How I can append new node in existing XML file

I've just begun learning DOM XML , so I'm currently at a very beginner level.
I have an existing XML file that I would like to add an additional node to before saving it to another variable.
how I can append new node in this file.
now this code is overwrite new data over old data
The code looks like this:
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.Result;
import javax.xml.transform.Source;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.TransformerFactoryConfigurationError;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import org.w3c.dom.Attr;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
public class VerbXMLWriter
    static String EVerb3;
    static String englishTranslate3;
    public void VerbXMLWriter(String EVerb, String englishTranslate )
         EVerb3 = EVerb;
         englishTranslate3=englishTranslate;
    File xmlFile = new File("VerbDB.xml");
    DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
    try
     DocumentBuilder builder = factory.newDocumentBuilder();
     Document document = builder.newDocument();
    Element root = document.createElement("Verb");
     document.appendChild(root);
     Element verb = document.createElement(EVerb3);
     verb.setAttribute("EnglishTranslate",englishTranslate3);
     root.appendChild(verb);
     Source xmlSource = new DOMSource( document );
     Result result = new StreamResult( new FileOutputStream(xmlFile) );
    TransformerFactory transformerFactory = TransformerFactory.newInstance();
    Transformer transformer =
    transformerFactory.newTransformer();
    transformer.setOutputProperty( "indent", "yes" );
     transformer.transform( xmlSource, result );
catch(TransformerFactoryConfigurationError factoryError )
    factoryError.printStackTrace();
   catch (ParserConfigurationException pc)
       pc.printStackTrace();
   catch (IOException io)
      io.printStackTrace();
   catch(Exception excep )
       excep.printStackTrace();
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<Verb>
<Play EnglishTranslate="playing" />
</Verb>Edited by: itb402 on Mar 9, 2008 6:05 AM

in your code you are already appending new nodes to the root node. so what exactly is your problem? The following steps are usually taken for appending a new node:
1. Read the XML document
2. Build a DOM tree
3. Navigate to the node under which you want to insert the new node
4. Create a new node.
5. Insert the new node to the node selected in point #3.
~Debopam

How can I write new objects to the existing file with already written objec

Hi,
I've got a problem in my app.
Namely, my app stores data as objects written to the files. Everything is OK, when I write some data (objects of a class defined by me) to the file (by using writeObject method from ObjectOutputStream) and then I'm reading it sequencially by the corresponding readObject method (from ObjectInputStream).
Problems start when I add new objects to the already existing file (to the end of this file). Then, when I'm trying to read newly written data, I get an exception:
java.io.StreamCorruptedException
at java.io.ObjectInputStream.readObject0(Unknown Source)
at java.io.ObjectInputStream.readObject(Unknown Source)
Is there any method to avoid corrupting the stream? Maybe it is a silly problem, but I really can't cope with it! How can I write new objects to the existing file with already written objects?
If anyone of you know something about this issue, please help!
Jai

Here is a piece of sample codes. You can save the bytes read from the object by invoking save(byte[] b), and load the last inserted object by invoking load.
* Created on 2004-12-23
package com.cpic.msgbus.monitor.util.cachequeue;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.RandomAccessFile;
* @author elgs This is a very high performance implemention of Cache.
public class StackCache implements Cache
    protected long             seed    = 0;
    protected RandomAccessFile raf;
    protected int              count;
    protected String           cacheDeviceName;
    protected Adapter          adapter;
    protected long             pointer = 0;
    protected File             f;
    public StackCache(String name) throws IOException
        cacheDeviceName = name;
        f = new File(Const.cacheHome + name);
        raf = new RandomAccessFile(f, "rw");
        if (raf.length() == 0)
            raf.writeLong(0L);
     * Whne the cache file is getting large in size and may there be fragments,
     * we should do a shrink.
    public synchronized void shrink() throws IOException
        int BUF = 8192;
        long pointer = getPointer();
        long size = pointer + 4;
        File temp = new File(Const.cacheHome + getCacheDeviceName() + ".shrink");
        FileInputStream in = new FileInputStream(f);
        FileOutputStream out = new FileOutputStream(temp);
        byte[] buf = new byte[BUF];
        long runs = size / BUF;
        int mode = (int) size % BUF;
        for (long l = 0; l < runs; ++l)
            in.read(buf);
            out.write(buf);
        in.read(buf, 0, mode);
        out.write(buf, 0, mode);
        out.flush();
        out.close();
        in.close();
        raf.close();
        f.delete();
        temp.renameTo(f);
        raf = new RandomAccessFile(f, "rw");
    private synchronized long getPointer() throws IOException
        long l = raf.getFilePointer();
        raf.seek(0);
        long pointer = raf.readLong();
        raf.seek(l);
        return pointer < 8 ? 4 : pointer;
     * (non-Javadoc)
     * @see com.cpic.msgbus.monitor.util.cachequeue.Cache#load()
    public synchronized byte[] load() throws IOException
        pointer = getPointer();
        if (pointer < 8)
            return null;
        raf.seek(pointer);
        int length = raf.readInt();
        pointer = pointer - length - 4;
        raf.seek(0);
        raf.writeLong(pointer);
        byte[] b = new byte[length];
        raf.seek(pointer + 4);
        raf.read(b);
        --count;
        return b;
     * (non-Javadoc)
     * @see com.cpic.msgbus.monitor.util.cachequeue.Cache#save(byte[])
    public synchronized void save(byte[] b) throws IOException
        pointer = getPointer();
        int length = b.length;
        pointer += 4;
        raf.seek(pointer);
        raf.write(b);
        raf.writeInt(length);
        pointer = raf.getFilePointer() - 4;
        raf.seek(0);
        raf.writeLong(pointer);
        ++count;
     * (non-Javadoc)
     * @see com.cpic.msgbus.monitor.util.cachequeue.Cache#getCachedObjectsCount()
    public synchronized int getCachedObjectsCount()
        return count;
     * (non-Javadoc)
     * @see com.cpic.msgbus.monitor.util.cachequeue.Cache#getCacheDeviceName()
    public String getCacheDeviceName()
        return cacheDeviceName;
}

Why cant i append objects to a file

i'm amazed that i cannot append objects to a file
as i did earlier in c++
it gives StreamCorrupt error

Ashutosh.options4u wrote:
i'm amazed that i cannot append objects to a file
as i did earlier in c++Whatever you did in C++ didn't involve ObjectOutputStream or Java Serialization. You can append anything but objects to a file in Java. The reasons are two:
(a) ObjectOutputStream writes a header which ObjectInputStream expects to find at the beginning of the stream and nowhere else
(b) closing an ObjectOutputStream and starting a new one to append to the same file breaks the specified semantics for preservation of object graphs under Serialization, which can only be implemented within a single instance of ObjectOutputStream.
it gives StreamCorrupt errorI agree.

Append stream object to existing file

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