Interview questions - Salesforce Developer - Part 1

1. Difference between Roles and Profiles
Roles, primarily control a user's record-level access permissions through role hierarchy and sharing rules.
Profiles, sets control a user's object- and field-level access permissions

2. Did you faced any situation where circular trigger take place, what's the error? And how did you avoid it?

A recursive trigger is one that performs an action, such as an update or insert, which invokes itself owing to,  say something like an update it performs.

eg in a before trigger, if you select some records and update them, the trigger will invoke itself.

To avoid, static variable 'locks' are used. Illustrated in the salesforce doc

"Static variables are only static within the scope of the request. They are not static across the server, or across the entire organization.

Use static variables to store information that is shared within the confines of the class. All instances of the same class share a single copy of the static variables. For example, all triggers that are spawned by the same request can communicate with each other by viewing and updating static variables in a related class. A recursive trigger might use the value of a class variable to determine when to exit the recursion."

Ref : http://www.salesforce.com/us/developer/docs/apexcode/Content/apex_classes_static.htm

https://help.salesforce.com/HTViewSolution?id=000133752&language=en_US

3.Rest vs SOAP API calls
REST API has a lightweight request and response framework and is easy to use, it’s great for writing mobile and web apps. Supports CRUD. supports both XML and JSON.

SOAP API uses the WSDL file as a formal contract between the API and consumer, it’s great for writing server-to-server integrations.

4. How to create a WSDL contract? In what case is it useful? Can we go without creating it?

5. What is action function in context of visual force?

https://developer.salesforce.com/docs/atlas.en-us.204.0.pages.meta/pages/pages_compref_actionFunction.htm

6. Batchable interface - What type of records are returned in case of execute function?

7. Governor limits -

https://developer.salesforce.com/docs/atlas.en-us.apexcode.meta/apexcode/apex_gov_limits.htm

8. Scenario - What happens when insert and update trigger on User object

Git every day commands

A normal GIT workflow of a developer is:
1. Pull the changes on git

git pull

2. Check if any of this files are changes.

git status

3. If merger error is there, manually merge it.
4. Add your changes to Git

git add -A or git add filename

5. Commit the changes

git commit -m "Message for commit"

6. Push the changes.

git push

For details please follow this cheat sheet: https://training.github.com/kit/downloads/github-git-cheat-sheet.pdf

Installing Open JDK 1.6 on Ubuntu

I was really confused while installing Java on my linux machine

Just to clarify they difference between JDK and JRE

What is JRE?

The Java virtual machine is used to compile the Java program which converts source code to byte code (a readable form of machine language). This byte code varies from one platform to platform.

Here JRE is used as a interpreter of byte code into machine code. So JRE is a interpreter for the Java program.

Now we can see what JDK is

JDK contains software development tools which are used to compile and run the Java program.

Both JDK and JRE contains the JVM.

JRE contains the runtime environment such as JVM and other Java classes (AWT, SWING), but does not contain any development tools such as a compiler or a debugger.

In a previous article, Mr Akshaya Bhatia, wrote about the basic tools of JDK. Please refer to this article since it has more details which are not included here.

Summary

The Java Virtual Machine's (JVM) function is to load the appropriate class files for executing a Java Program, and then to execute it.

The Java Runtime Environment (JRE) includes the JVM, as the JRE provides some standard libraries and the JVM which can be used to execute a Java program.

The Java Developers Kit (JDK) also includes the JVM, standard class libraries, and several other tools that a developer needs in order to create a Java program.

You can use the following commands to install it on Ubuntu:

sudo apt-get install openjdk-6-jre

sudo apt-get install openjdk-6-jdk

Analytics : Where is it going?

Analytics has come a large way today.
Recently, I attended a conference where in saw a new feature in Android 4.1 (Jelly fish)..its google now.
You can take a look at the video.Google Now predicts everything from the day to day data it has.

Then, i researched some more points where this analytics field is going and got to know that google also launched a prediction API in the past. Its a very interesting stuff to have. You can look at the documentation of Prediction API here.

Then, i was researching, what are the companies in India which are actually working on the Predictive analytics and the first name that came in is the Fractal Analytics, you can go through the blog here. These types of companies have a bright future, because everything works on prediction today. Its always a calculated risk which every business has to take.
Where to invest your money is the answer given by the companies like Fractal Analytics.

A few details what are the technology used by the analytics comapnies:
Let me take this opportunity to introduce you to the world of Hadoop and Map reduce as well.
Imagine you have a massive data which is saved in a RDBMS like MySQL and you are facing performance hits everyday when analyzing the data, then the databases like HBase which is the database of hadoop can help you. HDFS is the file system used in hadoop implementation. You should also know about MapReduce which is used to analyze this data or its the batch processor. These are open source communities, so you can very well go and explore them on Google.

So, the bottom line is Analytics is using open source technologies like Hadoop and MapReduce to predict the future of a human beings and has a long journey to make the world actually Robotic.

Engineer's become Entrepreneur's

Today most of the engineers in India are into software's.

Tell me what exactly we do there. Are we doing what exactly we wanted to do???

Now, the bigger question is WHAT EXACTLY WE WANT TO DO???

This question scribbles in my mind every day before i go to sleep. I do ask this question to my girlfriend as well. She says"Everything will be fine, don't worry".. And yes, the other day everything is really fine. We go to office, do the assigned work whole heartily and come back. But what ahead that...nothing..no meaning in life..

Now, i want to appreciate Rashmi Bansal. Yes she is the author of the three famous books for entrepreneur (Stay Hungry Stay Foolish, Connect the Dots and I have a dream.). The way she has presented the entrepreneur’s in all three books is just superb.

At least, me as a person gets some inspiration from this books. And I think I want to make a difference in the world and I start my journey with some thinking.

I wish every engineer reading this blog should think in a different style and propose some ideas so that we can make a difference in the society.

how to block incomming attacksBlock incoming attacks

Limit your exposure to the outside world by blocking incomming connections.
Start > Settings > Control Panel > Network ConnectionsRight click on "Local Area Network" And go to "Properties", In the scroll box, Click on "Internet Protocol (IP/TCP)" and then click on the "Properties" button, In the new window, Click on the "Advanced.." button, Then in the other new window go to the "Options" tab, Click on "TCP/IP Filtering" and hit "Properties", Check off "Enable TCP/IP filtering (All adapters)" next In the Above "TCP Ports" Click on the Radio button "Permit Only" and then add in the ports that you want people to be able to access... If you're running a web server add in 80, If you're running an FTP server add in 21... And so on... Then hit "OK" And close all the other windows, And reboot when it asks you too.
This way you can close the ports that you do not need to be open to the outside world. An alternative to this tweak could be running a firewall or enabling windows built in firewall. Please note that in order for other computers to connect to you, for example sending a file over AOL Instant Messenger or using Windows Messenger to send a file, make sure that the required port is not blocked on your system. Otherwise, nothing will go through.

Ways to get a users ip address.

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1: Intro
2: Tools you need.
3: Using x net vision.
4: Defind type of ports.
5: Grabb the ip.
6: Scanning the ip.
7: Ways of using the ip.
8: What if the ips proxyed.
9: How to proxy your ip.
10: Why proxy your ip.
11: Whats the purpose of proxying a ip.
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1: Intro
This text will tell you alot about ips and how to get them also tells you how to stop a user from obtaining your ip address this text i take no responcablity in what you do with it or how you use my knowledge most of what i will say in this text will tell you how a user gets your ip address then it will teach you how to shield your self so that a user off the net cant get your ip address many ways to get a ip and there is a few ways to stop that from taking place i will just be giving out one way of stoping that the other way is changing your ip address but no i will not teach that cause that is illegal what is said in this text some things are illegal some are not i strongly suggest that you read it and learn from it but dont use the info in a bad way.One thing i always say and stand by is dont use knowledge from the bad of man kind use it for the greater good.——————————————————————————————————————————————
2: Tools you need.
There are a few tools you will need to obtain a ip address i will tell you them and what they all do .X net vision.netstatwhoisormsdosNow i tell you what all those programs do.x-net-vision = its a program that gets the ips ports and host names of any ip thats connected to your ip.
netstat = is also a program that does the same thing as x net vision but this only gets the ips that are directly connected to your ip.whois = this is a program that tells you the ips isp and tells the address of the isp now for those that dont know here is what ip and isp meansip stands for internet protocolisp stands for internet service provider the one that provides you with your internet.
ms dos = this is command prompt some people likes it better some do not.its good for many things some commands are ping netstat -n netstat -a netstat those are ones we will be looking at.Actly all these can be found on my site www.net-demons-inc.com.
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3: Using x net vision.
Ok first off this part will tell you how to use x net vision and netstat viewer.Load x net vision up and click refresh you will see in the list view all ips and ports and host names that are connected to you right now.Double clicking any of those ips will bring up a box that you can copy the ip host name.With netstat viewer it will show you the ips directly connected to you right now double click those does the same.
Now whois open that type in the ip and click look up that will show you the info on the ip address.
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4: Defind type of ports.
This part of the text will defind a few ports that you might see.
505050015000510180800180808002now those are ports that you will see.5050 is the standard port for connecting to yahoo’s server.5001 and 5000 are voice ports for voice servers if your on voice you will see these ports on the ip.5101 is the standard port for sending and recieving pms.80 is the standard port for website browsing or getting a file from yahoo send file.
8001 8002 these are ports for loging into yahoo in website using proxys.8080 is also for website browsing
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5: Grabb the ip.
Now that you have read all that lets grab a ip usig x net vision.your first step is to figure out how your going to direct connect to this user i will tell you a bit about this.the things that you can get a ip from are.webcam viewing or showing.send a fileadd as a friend and send them a pmadd as a friend and voice chat with them.
Now lets talk about these really fast.If you plan on sending them a file or having them send you a file then you dont need them added to get there ip.if you plan on letting them see your cam or you see there cam you can get there ip and dont need them added to do so.now if you plan on using voice or pm to get the ip they must be added to your buddy list first.Now determon how your going to get there ip and i will tell you the methods are how you do doing all 5 of them.
Letting them view your cam.Open x net vision first click refresh make sure no pms are open just the dudes pm that you wanna get the ip for.when they get on your cam just refresh on x net vision you should see a new ip on there double click that new ip and that will be theresviewing there cam.Open x net vision make sure all pms are closed all chats are closed just his or her pm openclick refresh.click the accept cam invite and wait untill you see her or him then click refresh again double click the new ip thats his or her ip.Send a file.This is the easyst one to do honestly.first off if you are sending the file what you need to do is get x net vision up click refreshafter that send the file keep clickin refresh each 6 seconds you will see a ip and port 80 when you do thats there ip address double click it and copy.
when recieving a file do the same method open x net vision refresh then download the file and keep clicking refresh when you see port 80 double click it thats the ip.Send PmThis is the hardst one to do.First off the id must be added to your buddy list before you can get the ip off a pm.after he or she is added what you do is open x net vision click refresh double click her or his id off your buddy list and send a pm when he or she replys back you will get a ip on port 5101 thats there ip address.now voice is hard also.you have to do the same thing as send pm.then enable voice when x net vision gets port 5001 or 5000 thats there ip address this method can not work in chat.
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6: Scanning the ip.
Now this isnt required so i will tell a little about this.Get a scanner that scans a ip for open ports.and scan it the open ports is kinda like access to there pc and most of the ports that are open on a pc can be used for getting into there pc but thats all i tell about this.
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7: Ways of using the ip.
Now after you get there ip there are a few things you can do with this.
1: take the ip offline.
2: hack it.
3: see how fast it is.
4: flooding it.
now i dont support info on hacking or flooding a ip so i will tell you how to take a ip offline and how to see if the ips fast the other two is on you to learn and if you want to learn from me that will cost you money.Now to take a ip offline is pretty easy to do.i use the ping method a pod attact ping of deathcomand…. ping -l 6550 -n 200 ipused in ms dos i wont tell you how to use this but thats all i will say about this.
Now to test a ip and see how fast it isuse ms doscommand pingdo this ping ipping websitein msdos.
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8: What if the ips proxyed.
Now some people has there ip proxyed this makes it hard to get a ip because when you try to grab the ip all you get is a proxy.what does ip proxy means it means that you make your ip a proxy meaning the proxy ip becomes your ip address it dont change your ip just makes it so when you directly connect to someone the proxy holds the place of your true ip so they get a proxy and not a ip.
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9: How to proxy your ip.
There are many ways of doing this.My way is a program i made that uses a list of proxys and changes my ip to that proxy.another way is using a annous program that makes you stay annous over the net.
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10: Why proxy your ip.
the reason to proxy your ip is so that no one can get your real ip if your ip is proxyed then when they send a file or you view them or they view you or you add them and pm them any direct connectiong with you and them all they get is a proxy ip thats it no ip at all and if they do a whois on that proxy all they see is a website.
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11: Whats the purpose of proxying a ip.
the purpose is to make it hard to obtain your ip address so you dont get hacked or any thing.