Joseph Michael

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since Dec 08, 2018
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Recent posts by Joseph Michael

We have two tables

Employee Table
Address Table

Employee Table hbm definition will have the following



Address Table hbm definition will have the following




Currently the application throws the following exception when execute the following HQL query

from Address where primarykey = '1232';

More than one row with the given identifier was found: 1232, for class:
com.region.Employee (compact stack trace follows)
org.hibernate.loader.entity.AbstractEntityLoader.load
(AbstractEntityLoader.java:92)

Clarification

1. Will Address primary key will always have one similar primary key in  Employee?
2. Will the Address primary key might differs from Employee primary key column
3. Will the Address primary key will always have one similar address column value in Employee table?
4. When this issue might come?
5. How to fix the problem

Please refer hibernate in action page number 221. Many to one is really a one-to-one. We have defined so that it works properly. please go through the PDF 221 for more info - cpe.ku.ac.th/~plw/oop/e_book/hibernate_in_action.pdf

Regards.
2 weeks ago
I understand any api needs to be exposed as webservice needs wsdl file

Question:

1. Any Sample webservice example and wsdl file?
2. How to test webservice in a standalone PC??
3. Sample test case to verify the webservice?
2 months ago
I understand micro services can be deployed as separate service and memory can be allocated for each service

Question:

1. Sample micro service example which can be independently deployed?
2. Which server is best for deploying microservice - tomcat or jboss ??
3. How to test microservice in a standalone PC??
4. Sample test case to verify the microservice


2 months ago
Hi,

What are the differences between async vs. reactive ?

Thanks.
2 months ago
From an expert,

In imperative programming we spin up threads to do things in parallel.

In reactive programming we declare the unit of work and leave execution (i.e. concurrency) up to the runtime.

Questions

1. Does Java supports imperative and reactive programming? How?
2. Can someone explain with an example of imperative and reactive programming with an example?
3. Concurrency can be done via call back or futures. What is the difference between having a call back or using futures?

Thanks.

2 months ago
During a presentation by a scala engineer, i heard he explained due to the drawbacks of clock speed multi-core processor has been invented to solve the problem.

He also said, even though multi-core processor exist today it is not efficiently used until we do functional programming

Questions

1. What is a clock speed? what is the maximum clock speed exist so far? What are the limitations?
2. How does clock speed matters in terms of processor?
3. Does clock speed MHZ cannot be increased and that's the reason multi-core processor is invented?

Thanks
2 months ago
Hi Tim,

We have an application built using JDBC which is blocking I/O

JDBC will send a query to a database and hold up the thread making the query until the result comes back.

JDBC is a series of APIs that talk to a database, but is blocking.

Attempts to scale JDBC have been implemented by putting JDBC connections behind a thread pool, but when the thread pool gets saturated, it can eventually block at accepting new work, defeating the whole endeavor.

Blocking JDBC behavior requires threads to be put into I/O wait until receiving a response.

How to fix or convert the existing application which uses JDBC as Non Blocking I/O ??

Please advise.

Thanks.
2 months ago
Tim,

Can you please explain each question in detail to understand better?
2 months ago

if

pool of connection  Generally used network TCP UDP

pool of threads  Generally Server thread pool

How does it is same ???

Is not connection pool and thread pool are different?
2 months ago

1. Is Connection Pooling is different from Thread Pooling?
2. If One connection will be connected to One thread...How does thread pooling is going to affect Connection Pooling?
3. How does the Connection Pool and Thread Pool plays a significant role in Blocking I/O vs Non-Blocking I/O RDBMS?
2 months ago

1. what is the differences between connection and a thread?
2. when people say DB supports connection pooling does connecting pool size and thread are same?
3. why JDBC is a blocking I/O and R2DBC claims non-blocking which don't understand
4. pool of connection vs pool of threads

Need one or 2 practical example. If anything with image/diagram would be very much useful.

Thanks.
2 months ago
Hi,

for pagination - Skip and limit vs find and limit ??? Which one would be the best choice ???

Case#1 - Paginate using primary key

Case #2 - Paginate using some other column

Thanks.
7 months ago
You are right...Thank you So Much.....
7 months ago
Daniel Demesmaecker...It is nothing but Awesome Reply.....Thanks a lot....

I would like to hear more answers for many of my questions. I like the way you explain...

Would you be like to respond via email ? Please kindly let me know.
7 months ago
Thanks a lot for your kind reply. Need the clarification on the below

1. Do we need to create the web-inf folder?
2. Do we need to create SpringBootServletInitializer  class ? (Ex: https://stackoverflow.com/questions/27405713/running-code-after-spring-boot-starts)
3. Do we need to have component scan or just placing the classes files inside the war file would be sufficient ?
4. Do we need to create WebConfig.java and do any configurations to make it work?

Thanks in advance.
7 months ago