Using ServletOutputStream

Hi,
I wanted to use ServletOutputStream to send a file for download to the client, but i had a doubt before actually implementing it.
Suppose the file is very big (in the order of GB's), will the client see the "save as" popup from the browser before my server actually sends the whole file to the client ie., in another terms will the download start at the client when few bytes are sent from my server instead of waiting for the entire file to be sent and output stream to be closed.
Thanks,
Ashwin

The client application will usually display the 'save as' popup directly when the response headers have arrived. Some client applications will immediately start to download the file (Firefox and so on), while others will only start when the client actually clicks 'save' (IE and so on).
For the file streaming part, you may find this article useful as well: [http://balusc.blogspot.com/2007/07/fileservlet.html].

Similar Messages

Display gif files using servletoutputstream (again)

Hello,
I'm trying to display several gifs files in a html file. I extract all the files from an oracle database. I'm trying to use a servletoutputstream, but it does not difference between text and image.
Process:
1. Select html file from database
2. Go through each line of html file to find the links to gif files
- if gif :
3. Ask for the gif file detected and select from database
4. use servletoutputstream to display the file
- end of if
-else
5. display the line of text.
Is it possible to use a servletoutputstream to display several gifs and text content?
Is there one other solution to do it correctly?
Thanks in advance,
Angela.
The code I use is:
private void retrieveFile()
FileWriter fwHtml=null;
oracle.sql.BLOB blob=null;
InputStream in=null;
ServletOutputStream out=null;
ResultSet rsGif=null;
try
//Extract html file from the database
String query="SELECT * FROM DBFiles WHERE FILENAME='"+file+"'";
PreparedStatement ps = connection.prepareStatement (query);
ResultSet rs=ps.executeQuery();
rs.next();
String fileName=rs.getString("FILENAME");
if (fileName.indexOf("html")!=-1)
InputStream fis=rs.getAsciiStream(5);
//I read each line to know where the html file calls the links to the gif files
BufferedReader reader= new BufferedReader(new InputStreamReader(fis));
String line;
String mimeType="";
try{
while ((line=reader.readLine()) !=null)
if((line.indexOf("img src="))!=-1)
int imgIndex=line.indexOf("img src=");
int altIndex=line.indexOf(" alt=");
//I obtain the name of the gif file that I obtain from the database
String gifFile=line.substring(imgIndex+9,altIndex-1);
query="SELECT * FROM DBFiles WHERE FILENAME='"+gifFile+"'";
ps.clearParameters();
ps = connection.prepareStatement (query);
rsGif=ps.executeQuery();
rsGif.next();
blob=((OracleResultSet)rsGif).getBLOB("GIF");
String gifName=rsGif.getString("FILENAME");
mimeType = context.getMimeType(gifName);
response.setContentType(mimeType);
out = response.getOutputStream();
in=blob.getBinaryStream();
int bufferSize=blob.getBufferSize();
byte[] buffer = new byte[bufferSize];
int bytesRead=0;
int intBuffer=in.read(buffer);
while ((bytesRead=intBuffer)!= -1)
out.write(buffer,0,bytesRead);
in.close;
else
byte[] bString =line.getBytes();
mimeType = context.getMimeType(fileName);
response.setContentType(mimeType);
out.write(bString,0,line.length());
catch (IOException ioe) {
System.out.println("Unable to open Image file "); ioe.printStackTrace();
finally {
if (out != null) {
out.flush();
out.close();
ps.clearParameters();
connection.commit();
rsGif.close();
rs.close();
ps.close();
catch (SQLException sqle)
sqle.printStackTrace();
catch (Exception e)
e.printStackTrace();

Let's put it this way, since I don't have the patience to look at your code. HTML cannot have images embedded in it, it can only have links to images. So you could have a servlet that sends an image, but only a single image and nothing else. I see you have code to set the MIME type of the image, so I don't have to tell you about that.

Problem to output image using ServletOutputStream

Hallo everybody! Can anybody help me? I try to output image (jpeg) using ServletOutputStream. First I upload jpeg image to server disassemble it to binary data and save to database binary data, image length, and image type. Then I try to output image.
Here the code:
response.reset();
response.setContentType(strContentType);
ServletOutputStream sos=response.getOutputStream();
sos.write(buf,0,bflen);
sos.close();
variable buf is array of byte with binary data
bflen is image length
strContentType it image type (image/pjpeg)
I use JRun server 3.1
I tried to save an image file:
FileOutputStream fos = new FileOutputStream("test_logo.jpg");
fos.write(buf,0,bflen);
fos.close();
And I got an jpeg file.

I've done the exact same thing... almost. I have a
servlet that sends a jpeg file to an applet for
processing. Anyway, I did two things differently.
First I used the write(byte[]) rather than
write(byte[], int offset, int length). If you're
going to send the whole array anyway, don't bother
with the other parameters.
Second, I call flush() on the output stream before I
close it. I have a feeling this is why. Remember,
web connections are connectionless. You don't know if
the data was send or received. I assume what is
happening is that you try to send the data then close
the connection right away and the data may not get to
the destination.
Here's what I have. I don't think the content type
really matters but I know multipart/form-data is
binary.
response.setContentType("multipart/form-data");
response.getOutputStream().write(image.data);
response.getOutputStream().flush();
response.getOutputStream().close();
I'll try it. But I have problem to call getOutputStream() method. It produce IllegalStateExeption. I think that because implicit getWriter() method calls. (I use JSP)
Do you know how to reset somehow response to have ability to call getOutputStream()?

Show several gifs files using servletOutputstream

Hello,
I'm trying to display several gifs files in a html file. I extract all the files from an oracle database. I'm trying to use a servletoutputstream, but it does not difference between text and image.
Process:
1. Select html file from database
2. Go through each line of html file to find the links to gif files
- if gif :
3. Ask for the gif file detected and select from database
4. use servletoutputstream to display the file
- end of if
-else
5. display the line of text.
Is it possible to use a servletoutputstream to display several gifs and text content?
Is there one other solution to do it correctly?
Thanks in advance,
Angela.
The code I use is:
private void retrieveFile()
FileWriter fwHtml=null;
oracle.sql.BLOB blob=null;
InputStream in=null;
ServletOutputStream out=null;
ResultSet rsGif=null;
try
//Extract html file from the database
String query="SELECT * FROM DBFiles WHERE FILENAME='"+file+"'";
PreparedStatement ps = connection.prepareStatement (query);
ResultSet rs=ps.executeQuery();
rs.next();
String fileName=rs.getString("FILENAME");
if (fileName.indexOf("html")!=-1)
InputStream fis=rs.getAsciiStream(5);
//I read each line to know where the html file calls the links to the gif files
BufferedReader reader= new BufferedReader(new InputStreamReader(fis));
String line;
String mimeType="";
try{
while ((line=reader.readLine()) !=null)
if((line.indexOf("img src="))!=-1)
int imgIndex=line.indexOf("img src=");
int altIndex=line.indexOf(" alt=");
//I obtain the name of the gif file that I obtain from the database
String gifFile=line.substring(imgIndex+9,altIndex-1);
query="SELECT * FROM DBFiles WHERE FILENAME='"+gifFile+"'";
ps.clearParameters();
ps = connection.prepareStatement (query);
rsGif=ps.executeQuery();
rsGif.next();
blob=((OracleResultSet)rsGif).getBLOB("GIF");
String gifName=rsGif.getString("FILENAME");
mimeType = context.getMimeType(gifName);
response.setContentType(mimeType);
out = response.getOutputStream();
in=blob.getBinaryStream();
int bufferSize=blob.getBufferSize();
byte[] buffer = new byte[bufferSize];
int bytesRead=0;
int intBuffer=in.read(buffer);
while ((bytesRead=intBuffer)!= -1)
out.write(buffer,0,bytesRead);
in.close;
else
byte[] bString =line.getBytes();
mimeType = context.getMimeType(fileName);
response.setContentType(mimeType);
out.write(bString,0,line.length());
catch (IOException ioe) {
System.out.println("Unable to open Image file "); ioe.printStackTrace();
finally {
if (out != null) {
out.flush();
out.close();
ps.clearParameters();
connection.commit();
rsGif.close();
rs.close();
ps.close();
catch (SQLException sqle)
sqle.printStackTrace();
catch (Exception e)
e.printStackTrace();

I may be wrong, but I don't think HTML supports inlining image data for a page. I think you need to let the client process the HTML and make requests to your servlet for specific images; it is at this point they should be read from the database and returned to the client.
So I'll change your algorithm to
1. Select html from the database
2. Return it to the client
3. Client makes request for an image (<img src="servlet?image=name">) maybe
4. Servlet reads image from the db
5. Servlet set appropriate header information (image/gif etc)
6. Servlet outputs image data.

Problem setting Unicode (utf-8) in http header using tomcat

Hi:
I am trying to set a file name in utf-8 to http header using the following code:
response.setContentType("text/html; charset=utf-8");
response.setHeader("Content-disposition", "attachment; filename=解決.zip");
// I actually has file name in utf-8 here to set to the header, and I know that the name is correctly
// and I also looked into the response object MimeHeaders object and saw the head is correctly there
then write the content of zip file using ServletOutputStream.
The problem I have is that the file name is not displayed correctly when prompted to save or open in the pop up window next. I found out using Fiddler that the request header is wrong:
Content-disposition: attachment; filename=�zn��.zip
I am using Tomcat 5.0.28. Any idea how to get this working?
Thanks in advance!

You are setting the charset for the content to be UTF-8. (That is why the method is called setContentType.) But HTTP headers are not part of the content and so that has no effect on the header.
The original specification for HTTP only allowed US-ASCII characters in headers. It is possible that more recent versions have features that allow for non-ASCII header data, but I don't know if that is the case or how you would use those features if they exist.

Urgent! Urgent! - Problem writing unicode using ServletOutputStreamream

Hi,
I have a string of unicode for Japanese character, I am trying to write that using ServletOutputStream() or PrintWrite() but it doesn't show what I want to see.
My code is like this
private ServletOutputStream output;
response.setContentType("text/plain;charset="ISO-2022-JP");
output = response.getOutputStream();
output.println(nodeValue "_MENU_" i "_NAME=" treeBundle.getString(menuItem.getName()));
where treeBundle.getString(menuItem.getName()); returns a unicode stream from the properties file which is in the form of \u6a5f\u5668\u69cb\u6210\u60c5\u5831
This is an urgent,
Thanks,
pbode stream from the properties file which is in the form of \u6a5f\u5668\u69cb\u6210\u60c5\u5831
This is an urgent,
Thanks,
pb

Things are not as simple, I have a jsp file which writes the applet, a part of applet is written from the jsp which displays japanese character fine but the popup menu which is being generated dynamically by a servlet doesn't show the japanese character correctly.
I am writing this popup menu's code using ServletOutput stream.
In the jsp I did not set the font but the font-family as,
A {font-size: 8pt; color: #0C2D79; text-decoration: none; font-family: gothic, mincho, arial unicode ms;}
And it works fine as the applet code generated by jsp shows japanese code very well but not the code written by servlet.
Hope it explains!

ServletOutputStream and https connection

Hi,
We have a servlet that streams a PDF file into the ServletOutputStream of the response object. We set the content type in the header to be application/pdf. There is nothing special in the logic and there is nothging else in the response object except this stream of binary file.
However, when the application is run using https connection the browser would always issue a warning message "This page contains both secure and non-secure items. Would you like to view the non-secure items?" Why is this? Does it mean that the binary stream is not encrypted automatically if using ServletOutputStream? What do we need to do to ensure that the file we send through ServletOutputStream will be automatically encrypted when viewed in an https connection?
Please help.
Thanks
Eric

I've posted a work-around (see http://forum.java.sun.com/thread.jsp?forum=33&thread=239134) that may be helpful.
Good luck.
Jack

Problem while sending a jar to a Browser through servlet

Hi All,
In my project I need to show a link to a file which is present in one of the folders of my server,when the user clicks it should pop up a window saying that save or cancel.In my code i am using servletoutputstream to read the file through the servlet but the problem is when the user clicks it ,the extension and filename or getting lost.means i am getting the filename equal to my servlet name.This is not acceptable in my project as the user doesn't know after downloading what file it is.Please provide me a solution.Thanks in advance.
Regards,
Naveen

If the file is not generated dynamically, i.e. if it is static in a directory, why are you using servletoutputstream to read and send it to the browser? Why not just provide a href link to the file?

SendRedirect doesn't work!

Hi all!
I've got a strange problem:
when I use a PrintWriter for sending data to user in my servlets, response.sendRedirect("smth") works fine,
but when I started to use ServletOutputStream, sendRedirect stopped working!
Please help!
Thnak you

Once the data buffer to the client is flushed (you've actually sent data) the sendRedirect command won't do what you want it to. sendRedirect works on the client side similar to putting a <META redirect . . > tag in the head of your page, it doesn't redirect through the server.
If data has already been sent to the client it will display it and ignore your request for a redirect. PrintWriter was working because the data buffer wasn't flushed before you sent the sendRedirect through the response.
Why would you want to send output to a page that they were being redirected away from anyway?
JDB
SCJP/SCWCD

WAS 6.0 - Response already committed / OutputStream already obtained

Hello, we have struts code that is working fine in websphere 5, but not 6. I've seen this same kind of thing being post around, but haven't found one that closely resembles our simple setup. Below I've copied what our code looks like. Please help me to understand what the least-intrusive way would be to fix something simple like this, and let me know if more info is needed. FYI, we have tried returning null from the class, but this doens't seem to work. Also, some additional info is that we need this to work in WAS 5 and 6, because we have two different apps containing the same code, one of which is deployed (via EAR file) on 5 and the other 6. Thanks!
struts-config entry:
<action path="/streamFile" type="MyClass" scope="request" validate="false">
              <forward name="success" path=""/>
</action>
web.xml entry:
     <servlet-mapping>
          <servlet-name>opsconsoleServlet</servlet-name>
          <url-pattern>streamFile</url-pattern>
     </servlet-mapping>
Snippet of Class file:
public class MyClass extends Action {
     public ActionForward execute(ActionMapping mapping,
                     ActionForm form,
                    HttpServletRequest request,
                    HttpServletResponse response)
          throws Exception {
     ServletOutputStream out = response.getOutputStream();
     BufferedOutputStream bos = null;
     try {
               bos = new BufferedOutputStream(out);
                bos.write(<bytes, etc>);
     } catch(final MalformedURLException e) {
     throw e;
     } catch(final IOException e) {
     throw e;
     } finally {
     if (bos != null)
          bos.close();
     if (out != null)
          out.close();
     return mapping.findForward("success");
error from log:
[11/5/07 12:50:11:737 EST] 00000036 ServletWrappe E   SRVE0014E: Uncaught service() exception root cause FilterProxyServlet: Cannot forward. Response already committed.
[11/5/07 12:50:12:001 EST] 00000036 ServletWrappe E   SRVE0068E: Could not invoke the service() method on servlet opsconsoleServlet. Exception thrown : javax.servlet.ServletException: Cannot forward. Response already committed.
        at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:157)
        at com.ibm.ws.webcontainer.filter.WebAppFilterChain._doFilter(WebAppFilterChain.java:82)
error later in log:
[11/5/07 12:50:12:621 EST] 00000036 SRTServletRes W   WARNING: Cannot set status. Response already committed.
[11/5/07 12:50:12:627 EST] 00000036 SRTServletRes W   WARNING: Cannot set header. Response already committed.
[11/5/07 12:50:14:191 EST] 00000036 ServletWrappe A   SRVE0242I: [Communication] [/OpsConsole] [/WEB-INF/jsp/error/internalError.jsp]: Initialization successful.
[11/5/07 12:50:14:201 EST] 00000036 ServletWrappe E   SRVE0068E: Could not invoke the service() method on servlet /WEB-INF/jsp/error/internalError.jsp. Exception thrown : java.lang.IllegalStateException: SRVE0199E: OutputStream already obtained
        at com.ibm.ws.webcontainer.srt.SRTServletResponse.getWriter(SRTServletResponse.java:490)
        at org.apache.jasper.runtime.JspWriterImpl.initOut(JspWriterImpl.java:170)
        at org.apache.jasper.runtime.JspWriterImpl.flushBuffer(JspWriterImpl.java:163)
        at org.apache.jasper.runtime.PageContextImpl.release(PageContextImpl.java:227)

svguerin3 :
So this is something that worked in websphere 5 but not 6.. Are you sure this same code working on WAS5? This shouldn't. I guess you are trying to display the contents of the stream in a JSP page.If that's correct don't use
ServletOutputStream out = response.getOutputStream();
     BufferedOutputStream bos = null;
     try {
               bos = new BufferedOutputStream(out);
                bos.write(<bytes, etc>);
     }instead read the bytes in to an in memory object, add this in memory object to request param and then call findForward(). In the JSP page get this request attribute and do whatever you want.
Note: You can either use servletoutstream.write or RequestDispactcher.forward/redirect/response.sendRedirect.

Unusual problem while sending a message to many pe...

hi recently i found a strange problem in my phone.Whenever i send a message through groups or if i select and send it to like 10 ppl ,suddenly a error message pops up saying messaging already in use.It happens till the message is sent for each and every person and then stops.This problem started to arise after the firmware update.Please help me to solve this problem.

If the file is not generated dynamically, i.e. if it is static in a directory, why are you using servletoutputstream to read and send it to the browser? Why not just provide a href link to the file?

Open browser in backend

Hi,
First of all, when I click on the document link, the data will pull out from the database and display the contents within the browser by invoked the AFP web viewer plugin.
The method that I used to do that through setContentType("application/afp"), and using ServletOutputStream.
The case above happened when I only click on one document link.
However, I need to select multiple documents by checking the checkbox and print without opening them.
Therefore, I m just wondering that can I open the documents and invoke the plugin in the backend, which mean the documents is open up without user seeing it, is invisible to user. And then call the javaScript print to print the documents.
My concern is is it possible to do it this way?
Thanks

I expect some of your original description is happening on the client and some on the server. You didn't bother to explain which, so it's hard to understand. Perhaps you don't understand it yourself and that's your problem.
Anyway, using the HTTP protocol you can only return one thing in the response. What that "thing" can be depends on what's receiving the response, but in general if you're going to be returning more than one file in the response, you're going to have to package up the files according to the requirements of whatever is going to receive this multi-file package. So check the documentation of this AFP thing and see if it can receive multiple files, and if it can how it wants them packaged.

CharSet Ambiguity !!!

Dear All ...
I have a big confusion regarding playing with charsets in Java in general...
My problem is that I am working on arabizing the Lotus Notes Portlets, I finally reached to arabize the whole portlets (static & dynamic strings, i mean by dynamic those returned from the Domino server) but by altering the code of the java Portlets, and using a ServletOutputStream as the out object to write with on the rersponse object rather than a PrintWriter out object, the ServletOutputStream worked and the strings returned from Domino are now displayed in arabic inside the four portlets as desired, but PrintWriter didn't worked with me. Although i understood after reading in several Java Documnets concerned with Java I/O streams that the PrintWriter is more powerful than OutputStream, it can support more character sets and deals with unicode.It is written that the Reader and Writer Family of calsses are easier to internationalize because they are not dependent upon a specific character encoding. So My question is which is better -practically in terms of internationalization- PrintWriter or ServletOutputStream?
My Second qustion : Can I know the encoding of a certain retreived string (e.g str.getEncoding() or a similar method), and is it really possible to change the encoding of a string from any charset to any charset using the follwing algorithm :
String str = <arabic string to be displayed>
byte[] bytes = str.getBytes("WINDOWS-1256");
String subj = new String(bytes,"WINDOWS-1256");
out.println("Your string is :"+subj);
Is there restrictions when converting a string from a charset to another?
My third question, and the last: when using ServletOutputStream out for writing on the response object , and retreiving the translated strings from a ListResourceBundle it gives an ERROR OCCURRED! message on the rendered portlet show mode, but when retreiving using PropertyResourceBundle it worked, using a PrintWriter the opposite scenarion worked with me.
The problem with ListResourceBundle is that you cannot provide more than one bundle for the portlet, and hence you cannot provide a bilingual interface. When I tried to specify more than one resource tag under the portlet tag, it gives an error while parsing the provider.xml, and if you provide the following code:"
Locale l = pr.getLocale() ;
ResourceBundle b ;
b = pr.getPortlet().getResourceBundle(l);
It always contacts the ListResurceBundle class that you mentioned in the resource tag -which contains arabic strings in my case -regardless of the current local whether it en or ar.
Can any one give me a hand,to clarify these issues, I'll apreciate his help very much.

1) PrintWriters are easier to deal with. When you create your PrintWriter, you specify an OutputStream AND a character encoding. Anything written to the PrintWriter will be converted to the specified character encoding and then written to the OutputStream.
When reading a file, you can do the same - create a Reader using a specified character encoding. The file/stream will be read using the specified character encoding and converted into Java characters (char data type). All chars & Strings in Java are in Unicode (UCS-2) so once you have read data into a String, using a Reader, all your data is in a consistent format.
Use the Writer to write that data out to another format. Using Readers & Writers means you only have to worry about character encoding when you read & write data. Everything in between is just Strings.
2) Answered above. Strings are always in Unicode (UCS-2). What matters is how you create the String & how you write it. If in doubt, be explicit when reading/writing
3) You cannot change the encoding of a String - Your code will do the following:
a) convert a UCS-2 String to bytes in Windows-1256
b)create a new String (in UCS-2) from a byte array encoded in Windows-1256
4) When using ResourceBundles, all your translations should be part of the same bundle. You do not have multiple bundles.
Look at the HelloWorld sample in the JPDK - the one that has a "resource" directory. It has one resource bundle & multiple translations of that bundle - the translations are accessed based on the locale you request.

Why adding "Transfer-Encoding: chunked"?

I have a servlet which generating dynamic content for client, e.g, a JAR file for user to download. Since it's a binary file, in doGet() method, I use ServletOutputStream.write() to output bytes. And I explictly called setIntHeader("Content-Length", xxx). But in most cases, the client will get a HTTP response whose header includes "Transfer-Encoding: chunked" and it causes some error. I know it's the client's fault, but is there anyone tell me why WebLogic adds this "chunked" header to my servlet even I set "Content-Length"?


I see the exact same behaviour, (had to fix the clients; they should have to
          handle chunked
          transfers if they're truely 1.1 compliant).
          My issue is WL sends both a chunked response AND a Content-Length (even when
          I don't
          set it) and this is HTTP 1.1 non-compliant. - A bug.
          -simon tooke
          [email protected]
          "Tim Bao" <[email protected]> wrote in message
          news:3befdbda$[email protected]..
          > I have a servlet which generating dynamic content for client, e.g, a JAR
          file for user to download. Since it's a binary file, in doGet() method, I
          use ServletOutputStream.write() to output bytes. And I explictly called
          setIntHeader("Content-Length", xxx). But in most cases, the client will get
          a HTTP response whose header includes "Transfer-Encoding: chunked" and it
          causes some error. I know it's the client's fault, but is there anyone tell
          me why WebLogic adds this "chunked" header to my servlet even I set
          "Content-Length"?

Servlet to load Applet

Hi,
          I am trying to write a servlet that deliver an applet to any html page which
          requested for it. How should I go about doing it?
          Can I use URLClassLoader to load the applet class from network and then use
          ServletOutputStream to send the applet to the client's brower? If so, is
          there a method to write the class to the output stream?
          Would really appreciate any help on this.
          regards
          Ee Ming


thanks for your replay,
I tried your suggestion but whatever I do it seems that tha applet only brings the first 5-10k of the image from the servlet. This is the value I get from instr.read() or any other type of read method. The value of bytes is not always the same.
Now I also have something new. For images greater than 100k or so I get this error:
java.io.IOException: Broken pipe
     at java.net.SocketOutputStream.socketWrite(Native Method)
     at java.net.SocketOutputStream.socketWrite(Compiled Code)
     at java.net.SocketOutputStream.write(Compiled Code)
     at java.io.BufferedOutputStream.write(Compiled Code)
     at org.apache.jserv.JServConnection$JServOutputStream.write(Compiled Code)
     at java.io.BufferedOutputStream.write(Compiled Code)
     at java.io.FilterOutputStream.write(Compiled Code)
     at interorient.DBProxyServlet.doGet(Compiled Code)
     at javax.servlet.http.HttpServlet.service(Compiled Code)
     at javax.servlet.http.HttpServlet.service(Compiled Code)
     at org.apache.jserv.JServConnection.processRequest(Compiled Code)
     at org.apache.jserv.JServConnection.run(Compiled Code)
     at java.lang.Thread.run(Compiled Code)
I am using the Oracle Internet application server (ias 9i) which actualy uses the apache web listener.
It seems that this servlet-applet communication is really unstable. If you have anything that may help me it will be greatly appriciated. You can even e-mail me at [email protected]
thanks!

Using ServletOutputStream

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