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I recently needed to use JiBX to parse a XML document into domain objects that contained bidirectional associations with collections.  The issue started out as a simple NullPointerException since each child object did not have a reference back to its parent. 

After some searching on Google, the only suggestions that I came across had to do with using the post-set attribute, which gets called after the class has been unmarshalled.  For various reasons, most of which I did not want the domain classes tied to JiBX, I sought out a different solution.

The solution I came up with was to use a set-method for the collection instead of field.  So I replaced field=”fieldName” with set-method=”setFieldName”.  This set method ensures that the bidirectional association is properly defined. 

There is an argument to be made that I should be doing this anyway.  After all, the domain class probably should not let it be up to the caller to ensure the bidirectional association is properly defined, regardless if it is being called from JiBX or some other caller.

However there was one unintentional side affect.  The project is also using Hibernate.  The same domain classes were mapped using lazy associations.  This change to the set method in affect turned off the laziness.  The solution for this was to change the Hibernate mappings to use field access to bypass the set method.

We’ve added a new .NET technology blog that is specifically focused on Microsoft .NET development and Microsoft SQL Server. This blog is written my the various developers from our .NET team and will cover a broad range of topical technical issues. We hope you find articles like the recent one about IE 8 connectivity issues useful and a good read. Please feel free to offer us feedback as we’ll certainly need it.

If you have 5000 products in database, you may like to show them in pages on the screen. It’s a common request to only retrieve the records on a certain page. This query must be quick and efficient if we are talking about millions of records in a table for an AJAX control.

In Oracle, we can do this:

SELECT * from
(
SELECT *, ROWNUM as rownumber from Product order by name
)
where rownumber between (PageNbr - 1)*PageSize + 1 and PageNbr*PageSize

As you can see, this query needs to fetch all rows first then narrows down the result. A more efficient query is:

select *
from ( select a.*, rownum rnum
from ( select * from product order by name) a
where rownum <= PageNbr*PageSize)
where rnum >= (PageNbr - 1)*PageSize + 1

Oracle will optimize this query, so it is not as resource intensive as the first one.

In SQL Server 2005, we can do similar query:

WITH Temp AS
(
SELECT row_number() OVER (ORDER BY [name]) AS rowNum, * from Product
)
SELECT * FROM Temp
WHERE rowNum between (@PageNbr - 1) * @PageSize + 1 and @PageNbr * @PageSize
ORDER BY [name]

The query had been optimized in SQL Server as well.

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I just installed XMarks to see if I can start synchronizing my bookmarks between all of my various locations and all the browsers installed.  However soon after installing, I noticed that I would get the mixed content warning (the one telling you are downloading unsecure content from a secure page) every time I would go to our company portal page, which is always secured via SSL.

I double checked the sites using Firefox, and even IE 7 from another machine, and the warning did not appear.  I disabled the Smarter Search feature in XMarks and the warning went away.

I have only installed XMarks on IE 8 so I don’t know if it is specific to IE 8 or is a problem with other browsers in general.

Update:  As per Colin below this issue has been fixed with version 1.0.7.  I installed this version and the warning no longer appears.  It is refreshing to have such a quick response.

Paul Litwin posted an interesting article that discusses the four pillars of ASP.NET (Web Forms, MVC, AJAX, and Dynamic Data).

He said: “Microsoft used to present ASP.NET Web Forms vs. MVC as a choice between a car and a motorcycle. Both will get you to your job , but some (the majority of the population, I might add) prefer driving a car, while a sizable minority love their motorcycles which give you better gas mileage and independence, but don’t protect you in the rain. To stretch this analogy to its breaking point, let me suggest that ASP.NET AJAX is like riding a bicycle to work (lean and mean, best gas mileage, but it requires you to exercise for your commute and exposes you to the elements like the motorcycle) while Dynamic Data is like taking the bus to work (let metro do the driving for you.)”

You can read his blog entry here:

While calling Oracle stored procedure from Hibernate  there is couple of rules that we need to follow. There can be only one return value and this must be a reference cursor. This return reference cusor must be the first and only out value for the stored procedure. It is required that stored procedure must return a reference cursor to be used from Hibernate.

Here is my stored procedure which return book name and ISBN number for a given branch and for a given author

CREATE OR REPLACE PROCEDURE SP_LIB_DTL(p_cursor    out sys_refcursor,
                                       in_brnch_cd in number,
                                       in_auth_cd in number)
as
  bookName varchar2(8);
  ISBN     number;
begin
  bookName := null;
  ISBN     := 0;
  open p_cursor for
    select l.book_name, l.isbn_nbr
      into bookName, ISBN
      from LIB_BRNCH_DTL l
     where l.branch_code = in_brnch_cd
     and l.auth_code = in_auth_cd;

end;

HIbernate Mapping for return class and Named Query:

<?xml version=”1.0″ encoding=”utf-8″?>
<!DOCTYPE hibernate-mapping PUBLIC “-//Hibernate/Hibernate Mapping DTD 3.0//EN”
“http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd“>
<hibernate-mapping>
<class name=”com.org.lib.LibraryDetails”>
<id name=”ISBN” type=”long” />
<property name=”bookName” type=”string” />
</class>
 <sql-query name=”LIB_SP” callable=”true”>
 <return class=”com.org.lib.LibraryDetails”>
   <return-property name=”ISBN” column=”isbn_nbr” />
   <return-property name=”bookName” column=”book_name” />
 </return>
  {  call SP_LIB_DTL(? , :branchCD ,:authorCD) }
 </sql-query>
</hibernate-mapping>

Make sure you have used the correct database field name value for the column attribute for the return property mapping. You will get the following error if you don’t map the correct databse field name

could not execute query; bad SQL grammar [{  call SP_LIB_DTL(? , ?) }];
nested exception is java.sql.SQLException: Invalid column name

Here is the DAO implementation for executing query and to set the bind parameter values.

public  List selectBooks(final BigDecimal branchCode,final BigDecimal authorCode){
        return (List) getHibernateTemplate().execute(new HibernateCallback() {
              public Object doInHibernate(Session session) throws HibernateException, SQLException
              {
                  Query q = session.getNamedQuery(“LIB_SP”);
                  q.setLong(“branchCD”, branchCode.longValue());
                  q.setLong(“authorCD”, authorCode.longValue());
                  return q.list();
              }
          });
      }

Unidev has achieved Gold Certified Partner status with Microsoft along with 4 competencies. (Custom Development Solutions, Business Intelligence, ISV/Software Solutions, Data Management Solutions).

The Net Impact, a division of Unidev, specializes in search engine optimization, web design and web marketing.  In order to share some of our experiences and expertise in this space, our CEO, Greg Alexander, has created a new blog covering SEO and marketing topics: www.searchengineoptimizationstlouis.com. Greg’s goal for the blog goal is to examine the technical issues surrounding web marketing in detail.  Be sure to add this blog to your reader so you don’t miss any of the interesting posts to come.

As a .NET developer, I’m sure you have your own tricks to make your life easy. But you may still like to know more tricks on Visual Studio. Read this article to see if you know all of them…

Essential Visual Studio Tips & Tricks that Every Developer Should Know