BUG: Ubuntu 14.04 LTS not show USB 3.0 devices

Fix 1: sudo echo "blacklist uas" >> /etc/modprobe.d/blacklist.conf
Fix 2: sudo apt-get install libnss-myhostname

# sudo reboot

Top 10 Inheritance Interview questions

1.what is inheritance?

• inheritance is one of the oops concepts in java.inheritance is concept of  getting properties of one class object to another class object.
• Inheritance represents the IS-A relationship,also known as parent-child relationship.

2.what are the types of inheritance?

1.Multiple inheritance( java doesn't support multiple inheritance).
2.Multilevel inheritance.

3.How Inheritance can be implemented in java?

• Inheritance can be implemented in JAVA using below two keywords:

1.extends
2.implements

• extends is used for developing inheritance between two classes and two interfaces.
• implements keyword is used to developed inheritance between interface and class.

4.Why we need to use Inheritance?

1.For Code Re usability.
2.For Method Overriding.

5.what is syntax of inheritance?

public class subclass extends superclass{

//all methods and variables declare here
}

6.what is multilevel inheritance?

• Getting the properties from one class object to another class object level wise with different priorities.

• Check here for more points on Inheritance

6.what is Multiple inheritance?why Java Doesn't Support multiple Inheritance.

• The concept of Getting the properties from multiple class objects to sub class object with same priorities is known as multiple inheritance.
• In multiple inheritance there is every chance of multiple properties of multiple objects with  the same name available to the sub class object with same priorities leads for the ambiguity. also known as diamond problem. one class extending two super classes.
• Because of multiple inheritance there is chance of the root object getting created more than once.
• Always the root object i.e object of object class hast to be created only once.

1. Because of above mentioned reasons multiple inheritance would not be supported by java.
2. Thus in java a class can not extend more than one class simultaneously. At most a class can extend only one class.

• Check here for more points on Why java does not supports multiple inheritance

8.How do you implement multiple inheritance in java?

• Using interfaces java can support multiple inheritance concept in java. in java can not extend more than one classes, but a class can implement more than one interfaces.

Program:

interface A{

}
interface B{
}
class C extends interface A,B{
}

9.Can a class extend itself?

• No,A class can't extend itself.

10.What happens if super class and sub class having same field name?

• Super class field will be hidden in the sub class. You can access hidden super class field in sub class using super keyword.

Compare RESTful vs SOAP Web Services

There are currently two schools of thought in developing Web Services – one being the standards-based traditional approach [ SOAP ] and the other, simpler school of thought [ REST ].

This article quickly compares one with the other -

REST	SOAP
Assumes a point-to-point communication model–not usable for distributed computing environment where message may go through one or more intermediaries	Designed to handle distributed computing environments
Minimal tooling/middleware is necessary. Only HTTP support is required	Requires significant tooling/middleware support
URL typically references the resource being accessed/deleted/updated	The content of the message typically decides the operation e.g. doc-literal services
Not reliable – HTTP DELETE can return OK status even if a resource is not deleted	Reliable
Formal description standards not in widespread use. WSDL 1.2, WADL are candidates.	Well defined mechanism for describing the interface e.g. WSDL+XSD, WS-Policy
Better suited for point-to-point or where the intermediary does not play a significant role	Well suited for intermediated services
No constraints on the payload	Payload must comply with the SOAP schema
Only the most well established standards apply e.g. HTTP, SSL. No established standards for other aspects.  DELETE and PUT methods often disabled by firewalls, leads to security complexity.	A large number of supporting standards for security, reliability, transactions.
Built-in error handling (faults)	No error handling
Tied to the HTTP transport model	Both SMTP and HTTP are valid application layer protocols used asTransport for SOAP
Less verbose	More verbose

Published at DZone with permission of Jagadeesh Motamarri, author and DZone MVB. (source)

The two protocols have very different uses in the real world.

SOAP(using WSDL) is a heavy-weight XML standard that is centered around document passing. The advantage with this is that your requests and responses can be very well structured, and can even use a DTD. The downside is it is XML, and is very verbose. However, this is good if two parties need to have a strict contract(say for inter-bank communication). SOAP also lets you layer things like WS-Security on your documents. SOAP is generally transport-agnostic, meaning you don't necessarily need to use HTTP.

REST is very lightweight, and relies upon the HTTP standard to do it's work. It is great to get a useful web service up and running quickly. If you don't need a strict API definition, this is the way to go. Most web services fall into this category. You can version your API so that updates to the API do not break it for people using old versions(as long as they specify a version). REST essentially requires HTTP, and is format-agnostic(meaning you can use XML, JSON, HTML, whatever).

Generally I use REST, because I don't need fancy WS-* features. SOAP is good though if you want computers to understand your webservice using a WSDL. REST specifications are generally human-readable only.

How to Install the Linux Dynamic Update Client on Ubuntu

You will be able to install No-IP.com’s DUC on Ubuntu in just a few minutes with Terminal. Once you have opened up your Terminal window you will need to login as the “root” user. You can become the root user from the command line by entering “sudo -s” followed by the root password on your machine.

1. cd /usr/local/src/
2. wget http://www.no-ip.com/client/linux/noip-duc-linux.tar.gz
3. tar xf noip-duc-linux.tar.gz
4. cd noip-2.1.9-1/
5. make install

You will then be prompted to login with your No-IP.com account username and password.

If you get “make not found” or “missing gcc” then you do not have the gcc compiler tools on your machine. You will need to install these in order to proceed.

To Configure the Client

As root again (or with sudo) issue the below command:

• /usr/local/bin/noip2 -C (dash capital C, this will create the default config file)

You will then be prompted for your username and password for No-IP, as well as which hostnames you wish to update. Be careful, one of the questions is “Do you wish to update ALL hosts”. If answered incorrectly this could effect hostnames in your account that are pointing at other locations.

Now the client is installed and configured, you just need to launch it. Simply issue this final command to launch the client in the background:

• /usr/local/bin/noip2

Read the README file in the no-ip-2.1.9 folder for instructions on how to make the client run at startup. This varies depending on what Linux distribution you are running.

And you are done! The DUC should now be installed on Ubuntu.