While reading values from XML nodes for a bulk operation, we encountered the “ORA-04030: out of process memory when trying to allocate…” error raised by dbms_xslProcessor.valueOf procedure.

When I first searched the web, I found out that small PGA size or kernel parameters not large enough to allow enough RAM was the cause of the problem. Then I tried to tune the database and operating system parameters. However down that path madness lied. Soon enough I’ve found myself playing with parameters that are better left alone.

Then I tried XMLType API’s instead of the XMLDom API’s and the result was successful. Memory and SWAP usage significantly decreased.

How to read xml node values with XMLType

My XML to read looks like:

<PANELDTLS>
  <PANELDTL>
    <ENABLED_YN>Y</ENABLED_YN>
    <INSERT_YN>N</INSERT_YN>
    <LABEL_TX>ID</LABEL_TX>
  </PANELDTL>
  <PANELDTL>
    <ENABLED_YN>Y</ENABLED_YN>
    <INSERT_YN>N</INSERT_YN>
    <LABEL_TX>Description</LABEL_TX>
  </PANELDTL>
  <PANELDTL>
    <ENABLED_YN>Y</ENABLED_YN>
    <INSERT_YN>N</INSERT_YN>
    <LABEL_TX>Name</LABEL_TX>
  </PANELDTL>
  .
  .
  .
</PANELDTLS>

and I want an output like:

ENABLED_YN INSERT_YN LABEL_TX
---------- --------- -----------
Y          N         ID
Y          N         Name
Y          N         Description

Here is the query to read text node:

select dbms_xmlgen.convert(
         extract(column_value,'/PANELDTL/ENABLED_YN/text()').getStringVal(),
         1 /*means decrypt escape characters*/ ) enabled_yn,
       dbms_xmlgen.convert(
         extract(column_value, '/PANELDTL/INSERT_YN/text()').getStringVal(),
         1) insert_yn,
       dbms_xmlgen.convert(
         extract(column_value, '/PANELDTL/LABEL_TX/text()').getStringVal(),
         1) label_tx
from table( XMLSequence( xmltype(
'<PANELDTLS>
  <PANELDTL>
    <ENABLED_YN>Y</ENABLED_YN>
    <INSERT_YN>N</INSERT_YN>
    <LABEL_TX>ID</LABEL_TX>
  </PANELDTL>
  <PANELDTL>
    <ENABLED_YN>Y</ENABLED_YN>
    <INSERT_YN>N</INSERT_YN>
    <LABEL_TX>Description</LABEL_TX>
  </PANELDTL>
  <PANELDTL>
    <ENABLED_YN>Y</ENABLED_YN>
    <INSERT_YN>N</INSERT_YN>
    <LABEL_TX>Name</LABEL_TX>
  </PANELDTL>
</PANELDTLS>').extract('/PANELDTLS/PANELDTL')))

Uğur Koçak

Formspider Installer opens up a thank you web page when the installation completes and we count how many times we render the thank you page. This page serves to a much more important purpose too. We’ve felt like the end of the installation did not really reflect our sentiments about how happy we are that you are giving Formspider a shot. Our thank you page shows how we really feel about it.

Formspider surged passed 100 installations in just five weeks. This is amazing. Thanks to Formspider, we have met many people from all around the world. We exchanged ideas, received invaluable feedback and hopefully we were able to help them as well.

On behalf of the team, I would like to sincerely thank everyone who is giving Formspider a shot. We love to hear what people do with Formspider. Please don’t be a stranger. Let us know what you do. Send us an email, ask a question or get involved in social networks. We are here to help.

We believe Oracle Forms modernization is an important topic for many Oracle customers. We would like to share our experience and knowledge in how organizations can protect their Forms and PL/SQL investment. If you are interested in seeing this presentation at Oracle OpenWorld please vote for it on the Oracle Suggest-A-Session page.

Admittedly, the process to vote is a little tedious. If you don’t have an Oracle account, you have to sign up and then vote for at least three presentations in order for your vote to be valid. However, we promise the presentation will be totally worth your effort.

Vote for Forms Modernization: The PL/SQL Way now.

We are determined to help PL/SQL developers build amazing web applications. We believe Formspider is the best way to achieve this goal. To prove this, we are offering free Formspider training to anyone who is interested.

So how does this actually work? If you are located in Istanbul, Turkey just contact us to schedule the training.

If you are not located in Istanbul, we can come to your office anywhere in the world and provide a five day Formspider training completely free of charge. The training may be for one developer or hundred. All we ask from you is to pay for travel, lodging and a reasonable €100 Per Diem for the daily expenses of the trainer. The five day training itself is completely free.

Contact us now, let us show you how Formspider can help you build platform independent beautiful web applications with just PL/SQL.

We went live with the Formspider Online IDE and started observing user behavior. Something was not right. People were signing up but not really doing anything. A quick investigation revealed that we were having problems with the XML Editor. It was failing for more than 50% of our users. Some people didn’t have Java on their machines, some had the open SDK that did not support JavaFX and some had problems we could not figure out.

Formspider IDE was not a joyride for the lucky few who was able to run the editor either. On average, a user had to wait about two minutes before the IDE was ready for input. The 1.5 MB jar was downloaded quickly enough but it took ages for the computer to install the jar and getting it ready to run. The security alert that kept popping up was also very annoying from the user’s perspective.The state we were in with the Online IDE was clearly unacceptable.

JavaScript came to the rescue. We were actually smart enough to sponsor a coding contest for a JavaScript editor while we were working on the JavaFX one. The team of Bilal Gültekin and Bahattin Tozyılmaz were the winners. In the picture below you see Bilal receiving their bounty, a teddy bear filled with $2600 dollars. We are also looking forward to host both Bilal and Bahattin as our interns this summer.

The Award Ceramony

After the contest was over, Öskan took over the code base for the XML Editor in JavaScript and prepared it for production use. After several weeks of work, the editor was ready for beta testing. However, the problem was so severe that even a partially working editor written in JavaScript was better than a thoroughly tested editor written in JavaFX. So we skipped the beta pretty quickly. We were already annoying pretty much every user, how much worse could we really get?

After a few quick iterations, we were incredibly happy with the results. Now our new XML Editor written entirely in JavaScript loads instantly and runs for our every user. Most importantly, our users started to engage with the Online IDE. I see them creating panels, text fields and windows everyday.

If you used the Formspider Online IDE before and you did not have a pleasant experience at all, I apologize and kindly invite you to give it another try. If this is going to be your first time with the Online IDE, nevermind… It all works just fine.

I looked all over the Internet but was unable to find a solution, so I wrote my own code. It’s written for a Java Servlet but the same logic can be applied to other languages too. The servlet below sends a piece of JavaScript to the client that it builds dynamically and adds the necessary headers to the response so that the browser can cache it.

Here’s the code that gets the job done:

public class TestServlet extends HttpServlet {
    private static final String CONTENT_TYPE = "application/x-javascript";

    public void init(ServletConfig config) throws ServletException {
        super.init(config);
    }

    public void doGet(HttpServletRequest request,
                      HttpServletResponse response) throws ServletException, IOException {

        Calendar c1 = Calendar.getInstance();
        c1.clear();
        c1.set(2011,2,22,13,12);
        long lastModifiedDate = c1.getTimeInMillis();

        response.setContentType(CONTENT_TYPE);
        response.addDateHeader("Last-Modified",lastModifiedDate);

        PrintWriter out = response.getWriter();

        long lastFetchedDate = request.getDateHeader("If-Modified-Since");
        boolean notModified = false;
        if (lastFetchedDate>-1){
            if (lastModifiedDate<=lastFetchedDate){
                response.setStatus(HttpServletResponse.SC_NOT_MODIFIED);
                notModified = true;
            }
        }
        if (!notModified){
            System.out.println("test");
            out.println("var test = {};");
            out.println("test['a']='b';");
            out.println("alert(test['a']);");
        }

    }

    public void doPost(HttpServletRequest request,
                       HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }
} 

To keep the example simple, I used a static date for the last modified date.

Here is how you can include this servlet in an html document as a javascript file:

<html>
    <head>
    <script type="text/javascript" src="http://localhost/test/testservlet"></script>
    </head>
    <body>
    </body>
</html>

When you run this from an application server, the first time you access the page you will see the message “test” in application server console, meaning that the servlet did the necessary work and generated the JavaScript code. The next time you access the page, the JavaScript will already be cached by the browser. Therefore, even the alert still pops up when the page is accessed, you will not the see message “test” in the server console. Since the dynamically created JavaScript is already cached in the browser and the headers were set up correctly, the server did not bother to generate the code all over again and responded much faster just like it would if the JavaScript was actually in a static file. 

M. Serdar Biçer

The Installer currently supports Windows only. We are going to support other platforms but in the meantime, if you need Formspider installed to a different OS, contact us at contact@theformpider.com. We’d be happy to guide you through it.

Wrapping process makes PL/SQL source code unreadable. Developers can wrap package specifications, package bodies, functions, procedures, type specifications and type bodies. Unfortunately triggers cannot be wrapped. To wrap the trigger code you need to place your source code to a package or procedure and call it from the trigger.

There are two ways to wrap PL/SQL source code.

1. Wrapping PL/SQL source code with wrap utility

Wrap utility takes two parameters. First one (iname) is the PL/SQL source code file and the second one (oname) is the output file that will hold the wrapped code.

wrap iname=example_input_file.sql oname=example_output_file.plb

This is an easy way to wrap source code because you do not need to handle DDLs bigger than 32767 bytes. But this way, you need to save DDLs into different files and execute the wrap command frmo the command prompt for each file.

2. Wrapping PL/SQL source code with DBMSL_DDL package

The DBMS_DDL package contains an overloaded wrap API to wrap PL/SQL source code.

dbms_ddl.wrap(ddl varchar2, lb pls_integer, ub, pls_integer) return varchar2;

dbms_ddl.wrap(ddl dbms_sql.varchar2s, lb pls_integer, ub, pls_integer) return dbms_sql.varchar2s;

dbms_ddl.wrap(ddl dbms_sql.varchar2a, lb pls_integer, ub, pls_integer) return dbms_sql.varchar2a;

In this method of wrapping, developers need to handle CLOB values that are bigger than 32767 bytes. They need to convert CLOB values to either dbms_sql.varchar2s or dbms_sql.varchar2a format.

We wrapped all our source code the second way in Oracle 10.0.2.1. We liked the ability ti generate all the encoded scripts automatically in PL/SQL. The encoded scripts run just fine from SQLPlus or similar tool. However, when we run the scripts using JDBC, we have faced a problem. Some packages started to give the following error mesagge:

PLS-00753: malformed or corrupted wrapped unit

First, we tried to solve the problem with changing character encoding but this did not help us. Then we started again to investigate the problem and we found a really interesting statement in the following forum thread. site.

“This only happens if the last character of the wrapped code is at the end of a line.”

We looked over all our uncompiled packages and verified the problem. Then we found an odd solution to this strange bug. We started to break down the last character of the wrapped code to next line. It does not mess up the wrapped code and works just fine in different oracle 10g versions.

Here is the function which extracts the DDL of the specified object in dbms_sql.varchar2a format and then wraps the source code using the dbms_ddl.wrap utility. We used dbms_sql.varchar2a due to the length of our object DDLs. At the end, there is a code block which converts dbms_sql.varchar2a to CLOB. It breaks down the last character of the wrapped code to the next line if the last character of the wrapped code is at the end of the line.

function extractCodeWrapped(in_objectType_cd varchar2, in_objectName_tx varchar2)
return  clob
is
 v_ddl_index_nr number;
 v_cur_pos_nr number;
 v_next_pos_nr number;

 v_ddl_2a dbms_sql.varchar2a;
 v_wrapped_ddl_2a dbms_sql.varchar2a;

 v_wrapped_ddl_cl clob;

 cursor cur_objectDDL is
   select -1 line, 'create or replace'||chr(10) text from dual
   union all
   select line, text
   from user_source
   where type = in_objectType_cd
   and name = in_objectName_tx
   order by line;

begin
 dbms_lob.createtemporary(v_wrapped_ddl_cl,true);

 -- extract DDL of the object
 v_ddl_index_nr := 1;
 for rec in cur_objectDDL loop
   v_ddl_2a(v_ddl_index_nr) := rec.text;
   v_ddl_index_nr := v_ddl_index_nr + 1;
 end loop;

 -- wrap source code of the object
 v_wrapped_ddl_2a := dbms_ddl.wrap(v_ddl_2a,1,v_ddl_2a.count);

 -- Convert dbms_sql.varchar2a to CLOB
 for i in 1..v_wrapped_ddl_2a.count loop

   -- if it is the last line check the last character. If the last character is
   -- at the end of line, break down it to next line.
   if i = v_wrapped_ddl_2a.count then
     -- find the positions of line feeds (chr(10)) at the line
     v_cur_pos_nr := 0;
     v_next_pos_nr := 0;
     loop
       v_cur_pos_nr := instr(v_wrapped_ddl_2a(i), chr(10), v_cur_pos_nr+1);
       v_next_pos_nr := instr(v_wrapped_ddl_2a(i), chr(10), v_cur_pos_nr+1);

       exit when v_cur_pos_nr = 0 or v_next_pos_nr = (length(v_wrapped_ddl_2a(i))-1)
              or v_next_pos_nr = length(v_wrapped_ddl_2a(i));
     end loop;
     -- if the line length is 74, the last character is at the end of line.
     if (length(v_wrapped_ddl_2a(i)) - v_cur_pos_nr) = 74 then
       -- append the line as two lines; first one is until last character and
       -- second one is only last character
       dbms_lob.writeappend(v_wrapped_ddl_cl, v_cur_pos_nr, substr(v_wrapped_ddl_2a(i), 1, v_cur_pos_nr));
       dbms_lob.writeappend(v_wrapped_ddl_cl, 71, substr(v_wrapped_ddl_2a(i), v_cur_pos_nr+1, 71));
       dbms_lob.writeappend(v_wrapped_ddl_cl, 1, chr(10));
       dbms_lob.writeappend(v_wrapped_ddl_cl, 2, substr(v_wrapped_ddl_2a(i), v_cur_pos_nr+72, 1)||chr(10));
     else
       -- otherwise append the line directly
       dbms_lob.writeappend(v_wrapped_ddl_cl, length(v_wrapped_ddl_2a(i)),v_wrapped_ddl_2a(i));
     end if;
   else
     -- if it is not last line append the line directly
     dbms_lob.writeappend(v_wrapped_ddl_cl, length(v_wrapped_ddl_2a(i)),v_wrapped_ddl_2a(i));
   end if;

 end loop;
 -- add '/' character end of object wrap
 dbms_lob.writeappend(v_wrapped_ddl_cl,3,'/'||chr(10)||chr(10));

 -- return wrapped source code
 return v_wrapped_ddl_cl;
end;

Here is sample code which calls the function:

declare
 v_objectType_cd varchar2(200) := 'PROCEDURE';
 v_objectName_tx varchar2(255) := 'TEST_PROCEDURE';

 v_wrapped_ddl_cl clob;
begin
 v_wrapped_ddl_cl := extractCodeWrapped(v_objectType_cd, v_objectName_tx);
 dbms_output.put_line(v_wrapped_ddl_cl);
end;

Samet Basaran