Cloud Types and Service Models

Some of the characteristics that define cloud computing include metered usage, where we pay only for those IT resources that we use in the cloud.

Another characteristic is resource pooling, where the cloud provider is responsible for pooling together all of the physical resources like server hardware, storage, network equipment, and that's made available to cloud subscribers, otherwise called tenants.

Another characteristic is that we should be able to access our cloud IT resources over a network, and in the case of a public cloud that means access from anywhere over the Internet.

Rapid elasticity is another characteristic so that we can quickly provision resources and deprovision them as required, and this is often done through a self-provisioning web portal.

A public cloud is one whose services are potentially accessible to all Internet users. We say potentially because there might be a requirement to sign up for an account or pay a subscription fee, but potentially it is available. A public cloud has worldwide geographic locations, and that's definitely the case with Amazon Web Services. The cloud provider is responsible for acquiring all of the hardware and making sure it's available for the IT services that they sell as cloud services to their customers.

A private cloud, on the other hand, is accessible only to a single organization and not to everybody over the Internet, and that's because it's organization owned and maintained hardware. However, a private cloud still does adhere to the exact same cloud characteristics that a public cloud does. For example, having a self-provisioned rapid elasticity of pooled IT resources available, that's still a cloud. In this case it's private because it's on hardware owned by the organization. The purpose of a private cloud is really apparent in larger government agencies and enterprises where we can track usage of IT resources and then use that for departmental chargeback.

A hybrid cloud is the best of both worlds. The two worlds we're talking about are the on-premises IT computing environment and the cloud computing environment. We have to consider that the migration of on-premises systems and data could potentially take a long time. So, for example, we might have data stored on-premises and in the cloud at the same time. And this is possible, for example, using the Amazon Web Services Storage Gateway, where we've got a cached copy of data available locally on the Gateway appliance on our on-premises network, but it's also replicating that data into the cloud. We might also, as another example, have a hardware VPN that links our on-premises environment to an Amazon Web Services Virtual Private Cloud, essentially a virtual network running in the cloud.

A community cloud serves the same needs that are required across multiple tenants. For example, Amazon Web Services has a government cloud in the United States, where it deals with things like sensitive data requirements, regulatory compliance. It's managed by US personnel and it's also FedRAMP compliant. FedRAMP, of course, is the Federal Risk and Authorization Management Program. So having these specific types of clouds available, in this case the government cloud, is referred to as a community cloud.

Cloud computing service models.

 So what is a service model anyway? Well, as it applies to cloud computing, it really correlates to the type of cloud service that we would subscribe to. So let's think about IT components like virtual machines and databases and websites and storage. Each of these examples correlates to a specific type of cloud computing service model.

 Let's start with Infrastructure as a Service, otherwise called IaaS. This includes things in Amazon Web Services like EC2 virtual machines. Or S3 cloud storage, or virtual networks which are called VPCs, Virtual Private Clouds. That's core IT infrastructure. And so it's considered Infrastructure as a Service.

Another type of cloud computing model is Platform as a Service, otherwise called PaaS. This deals with things like databases or even things like searching, such as the Amazon CloudSearch capability.

Software as a Service is called SaaS, and this is the way we would deal with things like websites or using Amazon Web Services WorkDocs. Well we can work with office productivity documents like Excel and Word documents in the cloud.

Security as a Service is called SECaaS. This deals with security that's being provided by a provider. So we're essentially transferring that risk out to some kind of a hosted solution. And it comes in many forms. It could be spam or malware scanning done for email in the cloud. Or as we see here, we've got an option in Amazon Web Services called AWS Shield. The purpose of this offering is for distributed denial of service attack protection.

A DDoS occurs when an attacker has control of slave machines, otherwise called #zombies. And the collection of these on a network is called a #botnet. Well, the attacker can issue commands to those slaves so that they could attack a victim host, as pictured here, or an entire network. Such as to flood it with traffic thereby preventing legitimate traffic from getting to, for example, a legitimate website. And in many cases a lot of these botnets are actually for rent by malicious users to the highest bidder. So for a fee, potentially we could pay for the use of a botnet to bring down a network or a host. Now luckily with Amazon Web Services, this can be mitigated using AWS Shield. DDoS protection mechanisms will often do things like looking at irregular traffic flows and blocking certain IP addresses. 

Basic Agile Scrum Interview QA

AGILE

Agile software development refers to a group of software development methodologies based on iterative development, where requirements and solutions evolve through collaboration between self-organizing cross-functional teams. Agile methods or Agile processes generally promote a disciplined project management process that encourages frequent inspection and adaptation, a leadership philosophy that encourages teamwork, self-organization and accountability, a set of engineering best practices intended to allow for rapid delivery of high-quality software, and a business approach that aligns development with customer needs and company goals. Agile development refers to any development process that is aligned with the concepts of the Agile Manifesto. The Manifesto was developed by a group fourteen leading figures in the software industry, and reflects their experience of what approaches do and do not work for software development. Read more about the Agile Manifesto.

SCRUM

Scrum is a subset of Agile. It is a lightweight process framework for agile development, and the most widely-used one.

• A “process framework” is a particular set of practices that must be followed in order for a process to be consistent with the framework. (For example, the Scrum process framework requires the use of development cycles called Sprints, the XP framework requires pair programming, and so forth.)
• “Lightweight” means that the overhead of the process is kept as small as possible, to maximize the amount of productive time available for getting useful work done.

A Scrum process is distinguished from other agile processes by specific concepts and practices, divided into the three categories of Roles, Artifacts, and Time Boxes. These and other terms used in Scrum are defined below. Scrum is most often used to manage complex software and product development, using iterative and incremental practices. Scrum significantly increases productivity and reduces time to benefits relative to classic “waterfall” processes. Scrum processes enable organizations to adjust smoothly to rapidly-changing requirements, and produce a product that meets evolving business goals. An agile Scrum process benefits the organization by helping it to

• Increase the quality of the deliverables
• Cope better with change (and expect the changes)
• Provide better estimates while spending less time creating them
• Be more in control of the project schedule and state

1. What is the duration of a scrum sprint?

Answer: Generally, the duration of a scrum sprint (scrum cycle) depends upon the size of project and team working on it. The team size may vary from 3-9 members. In general, a scrum script complete in 3-4 weeks. Thus, on an average, the duration of a scrum sprint (scrum cycle) is 4 weeks. This type of sprint-based Agile scrum interview questions is very common in an agile or scrum master interview.

2. What is Velocity?

Answer: Velocity question is generally posed to understand if you have done some real work and familiar with the term. Its definition “Velocity is the rate at which team progresses print by sprint” should be enough. You can also add saying the important feature of velocity that it can’t be compared to two different scrum teams.

3. What do you know about impediments in Scrum? Give some examples of impediments.

Answer: Impediments are the obstacles or issues faced by scrum team which slow down their speed of work. If something is trying to block the scrum team from their getting work “Done” then it is an impediment. Impediments can come in any form. Some of the impediments are given as –

• Resource missing or sick team member
• Technical, operational, organizational problems
• Lack of management supportive system
• Business problems
• External issues such as weather, war etc
• Lack of skill or knowledge

While answering impediments related agile scrum interview questions remember that you may be asked the way to remove any of the mentioned impediment.

4. What is the difference and similarity between Agile and Scrum?

Answer: Difference between Agile and Scrum – Agile is a broad spectrum, it is a methodology used for project management while Scrum is just a form of the Agile that describes the process and its steps more concisely. Agile is a practice whereas scrum is a procedure to pursue this practice.

The similarity between Agile and Scrum – The Agile involves completing projects in steps or incrementally. The Agile methodology is considered to be iterative in nature. Being a form of Agile, Scrum is same as that of the Agile. It is also incremental and iterative.

5. What is increment? Explain.

Answer: This is one of the commonly asked agile scrum interview questions and a quick answer can be given this way. An increment is the total of all the product backlogs items completed during a sprint. Each increment includes all the previous sprint increment values as it is cumulative. It must be in the available mode in the subsequent release as it is a step to reach your goal.

6. What is the “build-breaker”?

Answer: The build-breaker is a situation that arises when there is a bug in the software. Due to this sudden unexpected bug, compilation process stops or execution fails or a warning is generated. The responsibility of the tester is then to get the software back to the normal working stage removing the bug.

7. What do you understand by Daily Stand-Up?

Answer: You may surely get an interview question about daily stand-up. So, what should be the answer to this question? The daily stand-up is an everyday meeting (most preferably held in the morning) in which the whole team meets for almost 15 minutes to find answer to the following three questions –

• What was done yesterday?
• What is your plan for today?
• Is there any impediment or block that restricts you from completing your task?

The daily stand-up is an effective way to motivate the team and make them set a goal for the day.

8. What do you know about Scrum ban?

Answer: Scrum-ban is a Scrum and Kanban-based model for the software development. This model is specifically used for the projects that need continuous maintenance, have various programming errors or have some sudden changes. This model promotes the completion of a project in minimum time for a programming error or user story.

Potatoes, Eggs, and Coffee Beans

Once upon a time a daughter complained to her father that her life was miserable and that she didn’t know how she was going to make it. She was tired of fighting and struggling all the time. It seemed just as one problem was solved, another one soon followed.

Her father, a chef, took her to the kitchen. He filled three pots with water and placed each on a high fire. Once the three pots began to boil, he placed potatoes in one pot, eggs in the second pot, and ground coffee beans in the third pot.

He then let them sit and boil, without saying a word to his daughter. The daughter, moaned and impatiently waited, wondering what he was doing.

After twenty minutes he turned off the burners. He took the potatoes out of the pot and placed them in a bowl. He pulled the boiled eggs out and placed them in a bowl.

He then ladled the coffee out and placed it in a cup. Turning to her he asked. “Daughter, what do you see?”

“Potatoes, eggs, and coffee,” she hastily replied.

“Look closer,” he said, “and touch the potatoes.” She did and noted that they were soft. He then asked her to take an egg and break it. After pulling off the shell, she observed the hard-boiled egg. 

Finally, he asked her to sip the coffee. Its rich aroma brought a smile to her face.

“Father, what does this mean?” she asked.

He then explained that the potatoes, the eggs and coffee beans had each faced the same adversity– the boiling water.

However, each one reacted differently.

The potato went in strong, hard, and unrelenting, but in boiling water, it became soft and weak.

The egg was fragile, with the thin outer shell protecting its liquid interior until it was put in the boiling water. Then the inside of the egg became hard.

However, the ground coffee beans were unique. After they were exposed to the boiling water, they changed the water and created something new.

“Which are you,” he asked his daughter. “When adversity knocks on your door, how do you respond? Are you a potato, an egg, or a coffee bean? “

Moral:In life, things happen around us, things happen to us, but the only thing that truly matters is what happens within us.

Which one are you?

Cloud Computing

Cloud computing is the on-demand delivery of compute power, database storage, applications, and other IT resources through a cloud services platform via the internet with pay-as-you-go pricing.

The best way to start with that is to compare it to traditional IT computing. Where on-premises on our own networks, we would at some point have a capital investment in hardware. So think of things like having a server room constructed, getting racks and then populating those racks with equipment. With things like telecom equipment, routers, switches, servers, storage arrays, and so on. Then, we have to account for powering that equipment. We then have to think about HVAC, heating, ventilation and air conditioning, to make sure that we've got optimal environmental conditions to maximize the lifetime of our equipment. Then there's licensing. We have to license our software. We have to install it, configure it and maintain it over time, including updates. So with traditional IT computing, certainly there is quite a large need for an IT staff to take care of all of our on-premises IT systems.

But with cloud computing, at least with public cloud computing, we are talking about hosted IT services. Things like servers and related storage, and databases, and web apps can all be run on provider equipment that we don't have to purchase or maintain. So in other words, we only pay for the services that are used. And another part of the cloud is self-provisioning, where on-demand, we can provision, for example additional virtual machines or storage. We can even scale back on it and that way we're saving money because we're only paying for what we are using. With cloud computing, all of these self-provisioned services need to be available over a network.

In the case of public clouds, that network is the Internet.

But something to watch out for is vendor lock-in. When we start looking at cloud computing providers, we want to make sure that we've got a provider that won't lock us into a proprietary file format for instance. If we're creating documents using some kind of cloud-based software, we want to make sure that data is portable and that we can move it back on-premises or even to another provider should that need arise.

Then there is responsibility. This really gets broken between the cloud provider and the cloud consumer or subscriber, otherwise called a tenant. So the degree of responsibility really depends on the specific cloud service that we're talking about. But bear in mind that there is more responsibility with cloud computing services when we have more control. So if we need to be able to control underlying virtual machines, that's fine, but then it's up to us to manage those virtual machines and to make sure that they're updated.

The hardware is the provider's responsibility. Things like power, physical data center facilities in which equipment is housed, servers, all that stuff. The software, depending on what we're talking about, could be split between the provider's responsibility and the subscriber's responsibility. For example, the provider might make a cloud-based email app available, but the subscriber configures it and adds user accounts, and determines things like how data is stored related to that mail service. Users and groups would be the subscriber's responsibility when it comes to identity and access management.

Working with data and, for example, determining if that data is encrypted when stored in the cloud, that would be the subscriber's responsibility. Things like data center security would be the provider's responsibility. Whereas, as we've mentioned, data security would be the subscriber's responsibility when it comes to things like data encryption. The network connection however is the subscriber's responsibility, and it's always a good idea with cloud computing, at least with public cloud computing, to make sure you've got not one, but at least two network paths to that cloud provider.

AmazonWeb Services (https://aws.amazon.com/free/) manages their own data center facilities and they are responsible for the security of them, as well as physical hardware security like locked server racks. They're responsible for the configuration of the network infrastructure, as well as the virtualization infrastructure that will host virtual machines.

The subscriber would be responsible for things like AMIs. An AMI, or A-M-I, is an Amazon Machine Image, essentially a blueprint from which we create virtual machine instances. We get to choose that AMI when we build a new virtual machine. We, as a subscriber, would also be responsible for applications that we run in virtual machines, the configuration of those virtual machines, setting up credentials to authenticate to the virtual machines, and also dealing with data at rest and in transit and our data stores.

We can see what is managed by AWS customers. So data, applications, depending on what we're configuring, the operating system running in a virtual machine, firewall configurations, encryption. However, what's managed by Amazon Web Services are the underlying foundation services, the compute servers, the hypervisor servers that we run virtual machines on. The cloud also has a number of characteristics. Just because you're running virtual machines, for instance, doesn't mean that you have a cloud computing environment.

A cloud is defined by resource pooling. So, we've got all this IT infrastructure pooled together that can be allocated as needed. Rapid elasticity means that we can quickly provision or de-provision resources as we need. And that's done through an on-demand self-provisioned portal, usually web-based. Broad network access means that we've got connectivity available to our cloud services. It's always available. And measured service means that it's metered, much like a utility, in that we only pay for those resources that we've actually used. So, now we've talked about some of the basic characteristics of the cloud and defined what cloud computing is.

The Elephant Rope

As a man was passing the elephants, he suddenly stopped, confused by the fact that these huge creatures were being held by only a small rope tied to their front leg. No chains, no cages. It was obvious that the elephants could, at anytime, break away from their bonds but for some reason, they did not.

He saw a trainer nearby and asked why these animals just stood there and made no attempt to get away. “Well,” trainer said, “when they are very young and much smaller we use the same size rope to tie them and, at that age, it’s enough to hold them. As they grow up, they are conditioned to believe they cannot break away. They believe the rope can still hold them, so they never try to break free.”

The man was amazed. These animals could at any time break free from their bonds but because they believed they couldn’t, they were stuck right where they were.

Like the elephants, how many of us go through life hanging onto a belief that we cannot do something, simply because we failed at it once before?

Failure is part of learning; we should never give up the struggle in life.