Dirty loading/checking in Hibernate

Every Hibernate session is cached.

It caches entities read from the database, changes made to entities, as well as added and removed entities; until the session is flushed (ie written to the database).

A session is said to be dirty when some changes have not yet been flushed. This session is flushed before the transaction is committed. It is perfectly normal to have a dirty session.

In simple words: Dirty data is the one which is not yet committed. Similarly, dirty session in hibernate contains modified data which is not yet committed :)

Configuration con = new Configuration();
con.configure("dirty.cfg.xml");
SessionFactory sf = con.buildSessionFactory();
Session session = sf.openSession();
Transaction trans = session.beginTransaction();

try
{
   Gender gender = (Gender)session.get(Gender.class, new Long(1));
   gender.setName("someName");
   session.getTransaction().commit();
   session.flush();
}
catch(Eception ex)
{
  ex.printStackTrace();
}

Here, we have not called update(), even then object state is written to the database. This is called automatic dirty checking. 

Hibernate monitors whether any changes are made in the session object and automatically synchronizes them to the database.

session.getTransaction.commit() is mandatory, else correct data will not reflect in the database.

Cascade and Inverse in Hibernate

In case of many-to-many relationship via intermediary table, CASCADE says whether a record will be
created/updated in the child table and INVERSE says whether a record will be created/updated in the
intermediary table

Example:
One student can have multiple phones, so Student class has property for Set of phones.
One Phone can be owned by multiple students, so Phone class has property for Set of Students.

This mapping is maintained in STUD_PHONE table.

So there are three tables -> STUDENT, PHONE and STUD_PHONE (intermediary) table.

Mapping might look like:

<set name="phoneset" table="stud_phone" cascade="save-update" inverse="true">
  <key column="mapping_stud_id">< /key>
  <many-to-many class="com.domain.Phone" column="mapping_phon_id"/>
</set> 

A new student object is created and 2 new phone objects are added to its set.
Now after calling session.save(student_obj) , depending upon CASCADE and INVERSE settings different queries will be fired.

Below are the different combinations->

1) CASCADE IS NONE and INVERSE is false

insert into STUDENT (Name, stud_id) values (?, ?)
insert into STUD_PHONE (mapping_stud_id, mapping_phon_id) values (?, ?)
insert into STUD_PHONE (mapping_stud_id, mapping_phon_id) values (?, ?)

2) CASCADE is NONE and INVERSE is true

insert into STUDENT (Name, stud_id) values (?, ?)

3) CASCADE is save-update and INVERSE is false

insert into STUDENT (Name, stud_id) values (?, ?)
insert into PHONE(phone_num, phone_id) values (?, ?)
insert into PHONE(phone_num, phone_id) values (?, ?)
insert into STUD_PHONE (mapping_stud_id, mapping_phon_id) values (?, ?)
insert into STUD_PHONE (mapping_stud_id, mapping_phon_id) values (?, ?)

4) CASCADE is save-update and INVERSE true

insert into STUDENT (Name, stud_id) values (?, ?)
insert into PHONE(phone_num, phone_id) values (?, ?)
insert into PHONE(phone_num, phone_id) values (?, ?)

Thus only when CASCADE was save-update the records were created in PHONE table, otherwise not.

When INVERSE is false (Student is the owner of relationship) the intermediary table STUD_PHONE was updated.

When INVERSE  is true (Phone is owner of relationship), so even though a new student was created, the intermediary table was not updated.

So in case of relation of two entities, CASCADE affects other entity table and INVERSE  affects intermediary table. So their effect is independent.

Remove Special Characters, Tabs, New Lines, Spaces and HTML Tags in SQL

We come across situations where we need to remove HTML tags , New Lines, Tabs and Spaces from a database column. Also we need to allow/disallow some special characters.

This can be achieved through the following SQL queries->


Remove HTML tags->

SELECT REGEXP_REPLACE(memotext,'<[^>]*>','') FROM TB_CITIALERTS_MEMO;



Remove new line(\n) and tabs(\t) ->

SELECT REPLACE(REPLACE(memotext,CHR(10),''),CHR(13),'') FROM TB_CITIALERTS_MEMO;

CHR(10) = New Line
CHR(13) = TAB



Replace Multiple spaces by Single space ->

SELECT REGEXP_REPLACE(memotext,'( ){2,}', ' ') FROM TB_CITIALERTS_MEMO;

The above query replaces more than 1 space by a single space.



Allow some special characters ->

SELECT REGEXP_REPLACE(memotext,'[^0-9a-zA-Z&@~_!|#$%*;,(){}/\. []') FROM TB_CITIALERTS_MEMO;

The above query allows those special characers that are included in this list [^0-9a-zA-Z&@~_!|#$%*;,(){}/\. []'), here you can omit the ones that you dont want to show.



We can also combine everything together as shown below ->

SELECT REGEXP_REPLACE(REPLACE(REPLACE(REGEXP_REPLACE(REGEXP_REPLACE(memotext,'<[^>]*>',''),'( ){2,}', ' '),CHR(10),''),CHR(13),''),'[^0-9a-zA-Z&@~_!|#$%*;,(){}/\. []') memotext
FROM TB_CITIALERTS_MEMO;

Restrict direct access to JSP's in your application

If you want to restrict users from directly accessing JSP's in your application , like when users directly type the url of the JSP in the browser without logging in.

In this scenario you have 2 options ->

Option 1) Put all JSP's under WEB-INF folder.

Option 2) Write the following code in web.xml file.

<security-constraint>
        <web-resource-collection>
            <web-resource-name>JSP Files</web-resource-name>
            <description>No direct access to JSP files</description>
            <url-pattern>*.jsp</url-pattern>
            <http-method>POST</http-method>
            <http-method>GET</http-method>
        </web-resource-collection>
        <auth-constraint>
            <description>No direct browser access to JSP files</description>
            <role-name>NobodyHasThisRole</role-name>
        </auth-constraint>
  </security-constraint>

Note: In the above code snippet you need to give the exact location of your JSP's ->  
<url-pattern>*.jsp</url-pattern> 
or 
<url-pattern>/Folder Name/*.jsp</url-pattern>

Work Culture in iGATE

Worked here for 4.5 years.

Well i joined Patni Computers System and within a year of joining, this company was taken over by iGATE.

Patni had a very good work culture and there were no strict timings, even a swipe of 6 hours was considered as full day.

The campus which was famously known as PKP (Patni knowledge Park) was the best in mumbai.

iGATE bought Patni and started enforcing its policies.

Phaneesh Murthy, the then CEO of iGATE was originally from INFOSYS and thus made Patni's policies similar to INFOSYS (Less Employee Friendly).

In iGATE it was mandatory to complete 45 hours swipe every week.

Within 1 year Patni was dissolved completely and a new brand iGATE was formed.

In iGATE the ratings given during appraisal were, 1 - Needs Improvement ,2 - Meets Expectations, 3 - Exceeds Expectations and 4-Outstanding. However since they followed bell curve methodology most of the guys were given 2 rating.

Normal increments were in the range of 7% to 11% but in case of promotions the increments given were around 20% (sometimes 14% and 27%  was also given). It all depended upon your current CTC (Low CTC = High Increment and High CTC = Low Increment).

iGATE had taken a huge loan from Apax partners to buy Patni. Apax did not get the said amount within time and hence they converted their debt into shares and sold it to Capgemini at 4 times the normal price.

Thus finally iGATE became Capgemini.

During this time they were looking to keep the cost as low as possible and thus fired many employees from iGATE. They were also forcefully giving 1 Rating to many employees so that they will get 0% increment.

This was the time many employees started looking for jobs outside and i was also one of them (I switched before it became Capgemini completely) .

Overall i would summarize as follows -

Patni - Best work culture (More like family).
iGATE - Little professional (More like Infosys)
Capgemini - Very Professional (Large Organization)

Below is the photo of PKP, It has all facilities in this campus (Shopping Mall, Gym, Swimming Pool, Library, Training center, Guest House etc.)