Pawankumar Jajara's Blog

Learn REST: A Tutorial: 12.3. Using REST in JavaScript

2012-10-01T15:45:00.001-07:00

Learn REST: A Tutorial: 12.3. Using REST in JavaScript

Bank Of America SJ Downtown Personal Bankers

2011-10-18T22:58:00.000-07:00

Hi friends,

I am writing about Bank Of America's Personal Bankers after experiencing one complete year of world class customer service. When I came to San Jose in August 2010, I was dying to get a Credit Card (of course not a secured credit card). I went to BOFA's SJ Downtown branch and my Personal Banker was Miguel Padilla, who got me approved for Student Platinum Credit Card with $1000 credit line with in no time. I am very curious about Banking and specially the Credit Card and nuts and bolts of Credit Card behind the scenes. He helped me enhancing my knowledge about CC working in US. After using the Credit Card for around 6 months, Miguel helped me getting my Credit Limit raised to $2500 by calling the appropriate division at BOFA. In Spring 2011, Miguel left SJ Downtown branch due to transfer and Alexander Navy became my new Personal Banker. He answered a whole bunch of my stupid queries about Online Banking, Credit Card limits, Credit Scores and how to build excellent good credit in United States. Recently I was confused about which card to choose for my current needs, he presented a variety of Credit Cards and few of them matched criteria satisfying my terms. Every time I called him, either he answered my questions on phone or replied my voice mails if he was busy. I would say, the Personal Bankers at SJ Downtown branch are very helpful, responsible and concerned about their customers. I would give an A+ to my personal Banker Alexander Navy and Miguel Padilla for their overall help, advises and concern for their customers. Interestingly, few of us know that the transfer limit for online banking is $2500 for incoming transfers in checking account, checkbooks can be printed from CostCo or Walmart, there is a charge associated with your deposit made using BOFA's teller, you can do more than 3 transfers in your Savings account while maintaining a minimum amount in account and so on. I would recommend him to be chosen as your Personal Banker but solely on your own responsibility. Bottom line is to choose the right path to manage your finances and balance assets and liabilities.

Completely remove MySql from Ubuntu 11.x

2011-08-05T10:50:00.000-07:00

Hi Friends,

Use the below command to completely remove MySql Server installation from Ubuntu 11.x:

sudo apt-get --purge remove mysql-server mysql-common mysql-client libmysqlclient15-dev libmysql-ruby

Resetting MySQL password

2011-06-03T17:15:00.000-07:00

MySQL Change root Password

How do I change MySQL root password under Linux, FreeBSD, OpenBSD and UNIX like operating system over ssh / telnet session?

Setting up MySQL password is one of the essential tasks. By default root user is MySQL admin account user. Please note that the Linux / UNIX root account for your operating system and MySQL root are different. They are separate and nothing to do with each other. Sometime your may remove mysql root account and setup admin as mysql super user for security purpose.

mysqladmin command to change root password

If you have never set a root password for MySQL server, the server does not require a password at all for connecting as root. To setup root password for first time, use mysqladmin command at shell prompt as follows:
$ mysqladmin -u root password NEWPASSWORD

However, if you want to change (or update) a root password, then you need to use the following command:
$ mysqladmin -u root -p'oldpassword' password newpass

For example, If the old password is abc, you can set the new password to 123456, enter:

$ mysqladmin -u root -p'abc' password '123456'
Change MySQL password for other users

To change a normal user password you need to type (let us assume you would like to change password for user vivek) the following command:
$ mysqladmin -u vivek -p oldpassword password newpass

Changing MySQL root user password using MySQL sql command

This is another method. MySQL stores username and passwords in user table inside MySQL database. You can directly update password using the following method to update or change password for user vivek:

1) Login to mysql server, type the following command at shell prompt:
$ mysql -u root -p

2) Use mysql database (type command at mysql> prompt):

mysql> use mysql;
3) Change password for user vivek, enter:

mysql> update user set password=PASSWORD("NEWPASSWORD") where User='vivek';
4) Finally, reload the privileges:

mysql> flush privileges;
mysql> quit

Source:[http://www.cyberciti.biz/faq/mysql-change-root-password/]

Chrome Spell problem

2011-03-17T16:32:00.001-07:00

Interview Report for Information Technology as Profession

2011-03-16T00:50:00.000-07:00

Interviewee Name: Badal Shah
Email ID: badal_5477@yahoo.com

Title: Software Developer
Company: eBay Inc.
Interview Place: Starbucks
Interview Date: 03/05/2011

Q1. How much you need to prepare after coming out of college to join Industry?
It really depends upon your knowledge, experience and exposure to technologies in software industry. You should know about domains and platforms in which you are interested. If you have taken your courses matching your area of interest, you will be fine as a fresher in IT industry. The only things you have to take care of are implementing your theories in projects and have a practical approach for solving problems. Furthermore, you will need to prepare yourself for job interviews and explain the interviewer what all technical work you did in your masters.

Q2. Is it necessary to take professional training before hunting a job in IT Industry?
San Jose State University has a great masters program offering a wide range of courses, focusing on latest software development techniques and tools. If you have insight knowledge of your coursework, you will be fine. There are professional courses like CCNA, SCJP, MCSE, SCSA and many others to clear your fundamentals in specific domain. But as I told earlier, if you haven’t took a course for particular technology or tool, you can build your skills using professional courses.

Q3. As a student, we learn a number of technologies and methodologies during coursework. Are they all helpful when you join the Software Industry?
Everything you have learned in the school will surely help you in your professional life. But there are always exceptional cases. Being a software engineer you might know a lot about web development, enterprise software development and mobile development frameworks because of the courses you took in masters. For example, I joined eBay Inc. as a software engineer and just work on the enterprise development side. But many times, I have to do some Quality Assurance for our products also. So it’s like switching back and forth between various aspects of software development. You might not need all the skills at the same time but it will be helpful to you if you know a lot about your field.

Q4. Is it fine if I just go with the regular coursework while there in university or I should do simultaneous research about latest technologies in Industry?
This part is totally optional. If you are able to cope up with your projects, assignments and research work in your courses, you can opt for more. It is always good to be prepared more in the field of Information Technology. Once you are synchronized with the latest happenings in industry, you can start implementing those in your personal projects. When you go for interview, you will have a positive impression about being familiar with latest trends in software industry.

Q5. How much time it usually takes for getting prepared for Industry?
It really depends and varies from individual to individual. If you have done internships before as a software engineer, you might be comfortable with the work environment and deadlines. Also if you were able to give your projects a professional touch, you are surely ready to join the software industry.

Q6. What is your regular schedule at eBay?
My schedule at eBay is pretty flexible and random. Generally I check emails in the morning about assigned tasks for the day. Then I have to be prepared for emergency meetings for our products planning and launch. Breakfast is free at our branch and the whole team enjoys it together. During work hours, I have to meet my manger sometimes to discuss critical problems in my project and solve them. I go to lunch with my colleagues at around 01:00 pm and come back to work in forty five minutes. I take coffee after sometime and have project discussions within my team. I and my teammates often play foosball, Xbox during evenings.

Q7. How much time is you involved in meetings at work?
Generally we have meetings on Tuesday and Wednesday regarding our ongoing projects and future projects. Apart from that I have one on one meeting at least once a week with my project lead. We use the agile approach for software development which needs a lot of communication between the stakeholders. Normally you have to be involved in meetings with your colleagues, team leaders, project leaders and managers. Communication is very important in software industry.

Q8. Have you deal with deadlines all the times or occasionally?
My projects are internal to eBay and do not have harsh deadlines. I am assigned something new to work upon every week and report to my team leader. But sometimes during product release and deployment, I have to deal with sharp deadlines with real time priorities.

Q9. What would you suggest if I got an offer from a startup company or IT giant like Microsoft? Which factors do I consider before choosing one of them?
It depends from person to person and the driving factors include job profile, interest, company’s business model, work environment, growth, co-workers, managers, compensation and personal choices about software platforms. If you have accurate details about the company and you know what you want to do, you can easily decide where to go.

Q10. Is it a good idea to target your companies of interest being a student and start focusing on specific technologies therein?
According to me, learning technologies targeting specific companies can narrow down your scope in IT industry. Most of the software companies change their business models, platforms, software tools and development areas often according to market requirements. For example, you are targeting Amazon and started learning web technologies like jQuery, AJAX, JSON, DOJO, YUI and Dreamweaver which they use a lot. What if they stopped using these scripting languages and tools after you graduate? So you should prepare yourself for a variety of companies and learn as much tools and techniques as you can. This will not only secure your future as an IT professional but also give you exposure to lot of technologies used in software industry.

Q11. Does your company allows work from home, and is it a good practice to do it?
Yes, eBay allows me to work from home but you should work from home only in case of emergencies. I am more productive at work place than at home. Once you are working from home, there are lots of factors which can break your concentration and decrease your work efficiency. I would prefer working from home rarely.

Q12. Which scripting languages and tools should I focus upon to get a job in web development?
There are lots of languages and tools you can learn to get a good job in web development but some are most important to know. JavaScript, jQuery, DOJO, JSON, YUI, AJAX, Shell Script, Perl, PHP and Python are the best languages to learn for web development. Tools include Netbeans, Eclipse, Jboss Server, Apache Ant and Apache Axis. These are the skills the employers will definitely look for a web development position.

Q13. How is the typical work culture in IT companies?
Every company has a different work culture in IT. But the common work patterns in all IT companies includes working in teams, high cohesion and coupling in work, working with deadlines and giving highest priority to work.

Q14. How is life at eBay being an IT Professional?
My life at eBay is full of self satisfaction. The best part of my job is that I am doing what I really like to do. They provide me all sorts of resources for development purpose and give liberty to think anything which can make their product more effective and optimized.

Q15. What are the best and worst part of your job and why?
In large companies you work in specific projects with limited responsibilities. You focus on very small part of the whole project and deliver your part. The best part is you don’t have to mess with lot of things at the same time and worst part is you are limited to certain aspects of your project.

Q16. Do they provide summer internships at eBay?
Yes they hire interns during summers from lot of universities. They hire interns from San Jose State University also. You can apply online and if your profile matches their requirements, you will surely get a call.

Q17. What are the chances of internship getting converted into fulltime jobs?
It depends on the project you worked upon during internship. If the project is huge and they want someone who knows a lot about it, they will hire you as a fulltime employee. Other factors deciding your status to fulltime includes market situations, technologies and project lead and critical requirements of project.

Q18. Do they sponsor H1-B visa for international students?
Yes they sponsor H1-B visa for international students.

Q19. Is language a barrier when working in multicultural environment with people from around the globe?
No, language is not a barrier because we use English as communication medium. Apart from that we use body language, reports and meetings to convey our messages to each other in teams.

Q20. Are duties formal or informal at your work place?
We have formal duties at eBay and everybody is given an authority and responsibility for a given work. Everybody knows what his /her boundaries are.

Q21. Which courses should I focus the most which can help me in my professional career?
You should focus upon CMPE202 (Software System Engineering), CMPE 203 (Software Engineering Management), CMPE 273 (Enterprise Distributed Objects), CMPE 275 (Enterprise Distributed Components), CMPE276 (XML for E-Business) and CMPE 294(Computer Engineering Seminar). All these courses are really helpful to you as a professional.

Q22. Should I go for Quality Assurance or Development in Information Technology?
Development is always a better choice than Quality Assurance. Development gives you new task, new problem and new challenge with every project. If you like taking challenges in life and want to learn a lot of things in software industry, development profile should best fit your needs. Quality Assurance is a mundane job and you will follow the same procedure for every piece of work you get. You can choose Quality Assurance too as career if you are good at testing things for their accurate working.

Q23. Is experience while working as a student assistant helpful while applying for a fulltime job?
Yes, it helps you a lot. The things you learn being a student assistant teaches you how to interact with your colleagues and work in team.

Q24. What is the normal size of teams at eBay?
It is approximately between fifteen and twenty and all team members work in high coupling with each other.
Q25. Is it worth working on resume and updating it along with experience and coursework?
Yes, working on resume really helps you get what you are capable of doing. The employer will look at your resume before he looks at you. By mentioning all your skills in your resume and updating it periodically with coursework and experience keeps your resume synchronized with your capabilities. It helps the employer decide whether you are the right guy for his company.

Q26. Does it matter if I work in Silicon Valley or somewhere else? Is it like that people work on the latest and current technologies here?
Silicon Valley is the best place to work if you want to stay in touch with latest technologies and use your potential to achieve the best. A large number of IT companies have their headquarters in Silicon Valley, opening gateways for potential software engineers. You can see your dreams coming true working here as an IT professional.

Building applications with ant without build.xml

2011-03-12T11:56:00.000-08:00

Hi friends,

You can also build using ant without the build.xml file.

ant -find "filename" build
ant -find "filename" deploy

For more details please visit the here

Using MySql on Fedora Core Linux

2011-03-01T00:20:00.000-08:00

Good Links to use MySql on Fedora Core:
http://www.knowledgesutra.com/forums/topic/31717-what-is-mysqls-default-root-password/

The default user is root and the password is, as they say blank for default.

You can set the root password by typing this:
# mysqladmin -u root password 'new-password'

You can then login by typing this:
# mysql -u root –p

Then you'll be prompted to provide the password you specified earlier.

You also might want to delete the anonymous user in the User's table. The default configuration of MySQL allows any user access to the system without
providing a username or password.

Delete the user by typing this:
# mysql -u root –p
mysql> use mysql
mysql> delete from user where User='';
mysql> quit

Installing MySQL Workbench using command in Fedora Linux

2011-02-25T09:27:00.000-08:00

Installing MySQL Workbench, on Fedora 13, is as follows:

Login as root
Open a terminal window in GNOME/KDE or switch to the command line
Issue the command:
rpm --import http://rpms.famillecollet.com/RPM-GPG-KEY-remi

Next, issue the command:
yum install http://rpms.famillecollet.com/remi-release-13.rpm

Open the file named remi.repo, found in the directory /etc/yum.repos.d, in a text editor (say vi) and change line no. 5 from:
enabled=0 to enabled=1
This will enable the [remi] repository.
Finally issue:
yum install mysql-workbench
to install MySQL Workbench on Fedora 13.

Henceforth, MySQL Workbench can be launched via a terminal window by issuing mysql-workbench or it can be found under Applications >Programming in GNOME.

Installing MySQL in Fedora Core Linux

2011-02-25T09:05:00.000-08:00

Hi Friends,

below are the steps to install MySQL on Fedora Core Linux:

Use yum to install both mysql command line tool and the server:yum -y install mysql mysql-server
Enable the MySQL service:/sbin/chkconfig mysqld on
Start the MySQL server:/sbin/service mysqld start
Set the MySQL root password:mysqladmin -u root password 'new-password'The quotes around the new password are required.

Videos for using Apache Ant with Eclipse

2011-02-20T23:03:00.000-08:00

Setting $PATH variable in Linux

2011-02-20T22:59:00.000-08:00

Set the following variables in .bash_profile file in root folder of your linux account:

JAVA_HOME=/usr/local/java
JDK_HOME=$JAVA_HOME
ANT_HOME=/usr/local/ant
PATH=$JAVA_HOME/bin:$ANT_HOME/bin:$PATH

Please make sure that you log off and log in back to see changes.

Thanks.

GUI Building Tools for Eclipse

2010-12-27T17:09:00.000-08:00

These are some of the Graphical User Interface building tools supported by Eclipse. You just have to follow the link and install the plugin into Eclipse. I personally used them in my projects in CMPE 273, under professor Mike Larkin. I would personally recommend Google's Windows Builder Pro which creates neat and efficient code in the Code Preview. Also the back and forth switching between the UI and Code is pretty fast allowing you to save you time. Please pick one according to your choice.

http://cloudgarden.com/jigloo/

http://www.eclipse-plugins.info/eclipse/plugin_details.jsp?id=451

http://www.javakb.com/Uwe/Forum.aspx/java-tools/1529/Swing-plugin-for-Eclipse

http://marketplace.eclipse.org/search/apachesolr_search/Genuitec,%20LLC

http://wiki.computerwoche.de/doku.php/programmierung/gui-builder_fuer_eclipse

http://stackoverflow.com/questions/29426/best-gui-designer-for-eclipse

The one which is the best according to my personal experience while working on University Record System project in CMPE 273 under Professor Mike Larkin:

WindowBuilder Pro User Guide - Google Java Developer Tools

Eclipse 3.6 (Helios)

http://dl.google.com/eclipse/inst/d2gwt/latest/3.6 [Copy this URL to use with Eclipse]

Eclipse 3.5 (Galileo)

http://dl.google.com/eclipse/inst/d2gwt/latest/3.5

[Copy this URL to use with Eclipse]

Eclipse 3.4 (Ganymede)

http://dl.google.com/eclipse/inst/d2gwt/latest/3.4

[Copy this URL to use with Eclipse]

For adding this plugin into Eclipse, Go to Help-> Install New Software ->Click Add -> Paste appropriate plugin link according to your Eclipse version.

Bingo !

Running a RMI Sample Application using Eclipse

2010-12-27T15:27:00.000-08:00

For Eclipse: Picture 2 and picture 3 show how to run in eclipse.

1. while configuring external tool give the name of the implementation class .

2. Run the server

3 Run the client .

I am attaching all the screenshots , hope it works

Book for Java Thread Programming

2010-12-27T15:24:00.000-08:00

Here is the suggestion for best book for Java Thread Programming:

Java Thread Programming
Paul Hyde
Sams, 1998
ISBN: 0672315858

Programming the Object Adapter in CORBA

2010-10-07T14:39:00.000-07:00

Programming with the POA

In order to create and use a POA, several steps are required. These steps may vary, however depending on the type of application being developed. The POA life cycle contains the following steps:

1. Get the Root POA

The first step is to get the root POA, which is managed by the ORB and provided to the application using the initial object name RootPOA. This is done as follows:

ORB orb = ORB.init(argv, null);
POA rootPOA = POAHelper.narrow(
 orb.resolve_initial_references("RootPOA"));

2. Define the POA Policies

As I mentioned earlier, the POA is an object adapter that can be used with multiple ORB products without the need for rewriting code. It is also designed to allow persistent objects (objects that are always alive even though the server that is hosting them may have been restarted). As a result, the developer is given control over the object's identity, state, storage, and life cycle. This is done through the use of policies related to threads, lifespan, object uniqueness, activation, and others.

There are seven policies that you have control over. These are:

Thread Policy

The appropriate thread usage technique for an application depends on several factors, including the number of objects the application will have, multi-threading support by the operating system, and the expect load on the system. In the BOA, multi-threading issues weren't addressed. The POA, however, has addressed this problem by providing a threading policy that can be used to specify the threading model to be used with the created POA. You can use:
- ORB_CTRL_MODEL: This model allows multiple requests to be processed concurrently by multiple threads, and the ORB is responsible for assigning requests to threads (this is the default threading model).
- SINGLE_THREAD_MODEL: In this model applications don't need to be thread-aware, and therefore all requests are processed sequentially (this however is not supported in J2SE 1.4).
Here is how you create a policy:
```
Policy p[] = new Policy[7];
p[0] = rootPOA.createt_thread_policy(
 ThreadPolicyValue.ORB_CTRL_MODEL)
```
In this example, we create an array of seven policy items. In the first item we have created a thread policy. Note however that the thread policy we created is the default anyway. This is a hypothetical example just to show you how to create policies.
Lifespan Policy

The POA supports two types of CORBA objects: the persistent object that was originally specified by CORBA, and a new object called a transient. A transient object cannot live beyond the process in which it is created; it can be used in situations where temporary objects are required (as in callbacks). A persistent object, on the other hand, can live beyond the process that created it. For example, if a client sends a request to a target object that isn't active (not running), the ORB will activate a server process for the object (if necessary) and then activate the object itself. It is important to note that (as you will see in the programming examples later in the article) the activation process is transparent to the client.

The lifespan policy can be used to specify the type of objects implemented in the created POA. You can make an object:
- TRANSIENT: The objects cannot outlive the POA instance in which they are created (this is the default policy).
- PERSISTENT: The objects can outlive the process in which they are created.
As an example, the following snippet of code shows how to create a lifespan policy where the objects are persistent:
```
p[1] = rootPOA.create_lifespan_policy(
 LifespanPolicyValue.PERSISTENT);
```
As you can see from the above two example policies, to create a policy use the create_nameOf_policy(policNameValue.value) syntax.
Object ID Uniqueness Policy

This policy can be used to specify whether the servants must have unique object identities. The value for this policy can be:
- UNIQUE_ID: Servants support exactly one object ID (this is the default).
- MULTIPLE_ID: A servant may support one or more object IDs.
The following snippet of code shows an example of a policy that allows a servant to have one or more object IDs:
```
p[2] = rootPOA.create_id_uniqueness_policy(
 IdUniquenessPolicyValue.MULTIPLE_ID);
```
ID Assignment Policy

This policy can be used to specify whether object IDs are generated by the application or by the ORB. The options are:
- USER_ID: Objects are assigned unique IDs only by the application.
- SYSTEM_ID: Objects are assigned unique IDs by the POA (this is the default). Note that if the lifespan policy is set to PERSISTENT then assigned object IDs must be unique across all instantiations of the same POA.
As an example, the following snippet of code shows how to create an assignment policy where object IDs are generated by the application:
```
p[3] = rootPOA.create_id_assignment_policy(
 IdAssignmentPolicyValue.USER_ID);
```
Servant Retention Policy

This policy specifies whether the created POA retains active servants in an object map. The options are:
- RETAIN: Indicates the POA will retain active object in a map (this is the default).
- NON_RETAIN: Active objects are not retained.
The following snippet of code shows an example of a servant retention policy specifying that active objects are not retained by the POA in an object map:
```
p[4] = rootPOA.create_servant_retention_policy(
 ServantRetentionPolicyValue.NON_RETAIN);
```
Request Processing Policy

Use this policy to specify how you wish requests to be processed by the created POA. The options are:
- USE_ACTIVE_OBJECT_MAP_ONLY: An OBJECT_NOT_EXIST exception is thrown if the object ID is not found in the active object map (this is the default). Note however, in order to use this you must set the ServantRetentionPolicyValue to RETAIN.
- USE_DEFAULT_SERVANT: If the object ID is not found in the active object map or the servant retention policy is set to NON_RETAIN then the request is dispatched to the default servant.
- USE_SERVANT_MANAGER: If the object ID is not found in the active object map or the NON_RETAIN server retention policy is present, the servant manager is given the opportunity to locate or activate a servant or raise an exception.
The following snippet of code shows how to create a request processing policy where requests are dispatched to the default servant:
```
p[5] = create_request_processing_policy(
 RequestProcessingPolicyValue.USE_DEFAULT_SERVANT);
```
Implicit Activation Policy:

This policy specifies whether implicit activation of servants is supported in the created POA. The options are (the default is none):
- IMPLICIT_ACTIVATION: Implicit activation of servants. Note however that this requires SYSTEM_ID and RETAIN policies to be present.
- NO_IMPLICIT_ACTIVATION: No implicit servant activation.

Note that the root POA always has the following policies:

Thread policy: ORB_CTRL_MODEL.
Lifespan policy: TRANSIENT.
Object ID uniqueness: UNIQUE_ID.
ID assignment policy: SYSTEM_ID.
Servant retention policy: RETAIN.
Request processing policy: USE_ACTIVE_OBJECT_MAP_ONLY.
Implicit activation policy: IMPLICIT_ACTIVATION.

3. Create the POA

Create a new POA to allow you to define specific policies. A new POA is created as a child of an existing POA using the create_POA on the parent POA. When creating a new POA, you need to pass the following information:

Name of the POA, which must be unique with respect to all other POAs with the same parent.
POA Manager to be associated with the new POA. If null is passed then a new POA manager will be created.
A policy list to be associated with the new POA.

The following snippet of code shows how a POA is created:

POA poa = rootPOA.create_POA(
 "childPOA", null, policy);

4. Activate the POAManager

A POAManager is associated with one or more POA objects. It is responsible for controlling the processing state of the POAs. The POAManager may have one of the following states:

Holding: Associated POAs queue incoming requests (this is the default).
Active: Associated POAs start processing requests.
Inactive: Associated POAs rejects new requests as well as requests that haven't begun executing.
Discarding: Associated POAs will discard incoming requests.

When a POAManager object is created, it is in a HOLD state by default. In other words, it is not automatically activated. It is activated as follows:

poa.the_POAManager().activate();

Without this statement, all calls to a servant will hang in a queue because the POAManager is in a HOLD state.

5. Activate the Servants

If the USE_DEFAULT_SERVANT policy is set, the server application requests the POA to activate unknown objects by having the POA invoke a single servant no matter what the object ID is. The server application registers this servant with set_servant.

If, on the other hand, the RETAIN policy is in effect, the servant and its associated object ID are entered into the active object map of the appropriate POA. This activation can be accomplished in one of the following three ways:

The server application explicitly activates individual objects through the activate_object or activate_object_with_id operations.
The server application instructs the POA to activate objects on demand by having the POA invoke a user-supplied servant manager. The server manager is registered using the set_servant_manager operation.
If the IMPLICIT_ACTIVATION policy is also set, the POA may implicitly activate an object when the server application attempts to obtain a reference for a servant that is not already active.

If, however, the NON_RETAIN policy is in effect, the POA may use either a default servant or a servant manager to locate an active servant. Note, however, that from the POA's point of view, the servant is active only for the duration of that one request. The POA doesn't enter the servant-object association into the active object map.

6. Create the Object Reference

Once an object reference is created in a server, it can be exported to clients. An object reference contains information related to object identity and others required by the ORB to identify and locate the server and the POA with which the object is associated. Object references can be created in three ways:

Explicitly activate a servant and associate it with an object reference: the following snippet of code shows how this can be done using the servant_to_reference operation to map an activated servant to its corresponding object reference:

org.omg.CORBA.Object obj =
 orb.resolve_initial_references("NameService");
NamingContextExt rootctx =
 NamingContextExtHelper.narrow(obj);
NameComponent nc[] = rootctx.to_name(
 "PersistentMathServer");
rootctx.rebind(nc,
 poa.servant_to_reference(servant));

Server application directly creates a reference: this can be done as shown in the following snippet of code:

Context ctx = new InitialContext();
ctx.rebind("MathServer",
 poa.create_reference_with_id(
   id, tie._all_interfaces(poa, id)[0]));

Server application causes a servant to implicitly activate itself: this is possible when the POA has been created with the IMPLICIT_ACTIVATION policy set.