Thursday, 25 June 2015

How Amazon’s DynamoDB helped reinvent databases

In the earliest days of Amazon.com SQL databases weren’t cutting it, so the company created DynamoDB and in doing so helped usher in the NoSQL market

Behind every great ecommerce website is a database, and in the early 2000s Amazon.com’s database was not keeping up with the company’s business.

Part of the problem was that Amazon didn’t have just one database – it relied on a series of them, each with its own responsibility. As the company headed toward becoming a $10 billion business, the number and size of its SQL databases exploded and managing them became more challenging. By the 2004 holiday shopping rush, outages became more common, caused in large part by overloaded SQL databases.

Something needed to change.
But instead of looking for a solution outside the company, Amazon developed its own database management system. It was a whole new kind of database, one that threw out the rules of traditional SQL varieties and was able to scale up and up and up. In 2007 Amazon shared its findings with the world: CTO Werner Vogels and his team released a paper titled “Dynamo – Amazon’s highly available key value store.” Some credit it with being the moment that the NoSQL database market was born.

The problem with SQL
The relational databases that have been around for decades and most commonly use the SQL programming language are ideal for organizing data in neat tables and running queries against them. Their success is undisputed: Gartner estimates the SQL database market to be $30 billion.

But in the early to mid-2000s, companies like Amazon, Yahoo and Google had data demands that SQL databases just didn’t address well. (To throw a bit of computer science at you, the CAP theorem states that it’s impossible for a distributed system, such as a big database, to have consistency, availability and fault tolerance. SQL databases prioritize consistency over speed and flexibility, which makes them great for managing core enterprise data such as financial transactions, but not other types of jobs as well.)

Take Amazon’s online shopping cart service, for example. Customers browse the ecommerce website and put something in their virtual shopping cart where it is saved and potentially purchased later. Amazon needs the data in the shopping cart to always be available to the customer; lost shopping cart data is a lost sale. But, it doesn't necessarily need every node of the database all around the world to have the most up-to-date shopping cart information for every customer. A SQL/relational system would spend enormous compute resources to make data consistent across the distributed system, instead of ensuring the information is always available and ready to be served to customers.

One of the fundamental tenets of Amazon’s Dynamo, and NoSQL databases in general, is that they sacrifice data consistency for availability. Amazon’s priority is to maintain shopping cart data and to have it served to customers very quickly. Plus, the system has to be able to scale to serve Amazon’s fast-growing demand. Dynamo solves all of these problems: It backs up data across nodes, and can handle tremendous load while maintaining fast and dependable performance.

“It was one of the first NoSQL databases,” explains Khawaja Shams, head of engineering at Amazon DynamoDB. “We traded off consistency and very rigid

querying semantics for predictable performance, durability and scale – those are the things Dynamo was super good at.”

DynamoDB: A database in the cloud
Dynamo fixed many of Amazon’s problems that SQL databases could not. But throughout the mid-to-late 2000s, it still wasn’t perfect. Dynamo boasted the functionality that Amazon engineers needed, but required substantial resources to install and manage.

The introduction of DynamoDB in 2012 proved to be a major upgrade though. The hosted version of the database Amazon uses internally lives in Amazon Web Services’ IaaS cloud and is fully managed. Amazon engineers and AWS customers don’t provision a database or manage storage of the data. All they do is request the throughput they need from DynamoDB. Customers pay $0.0065 per hour for about 36,000 writes to the database (meaning the amount of data imported to the database per hour) plus $0.25 per GB of data stored in the system per month. If the application needs more capacity, then with a few clicks the database spreads the workload over more nodes.

AWS is notoriously opaque about how DynamoDB and many of its other Infrastructure-as-service products run under the covers, but this promotional video reveals that the service employs solid state drives and notes that when customers use DynamoDB, their data is spread across availability zones/data centers to ensure availability.

Forrester principal analyst Noel Yuhanna calls it a “pretty powerful” database and considers it one of the top NoSQL offerings, especially for key-value store use cases.

DynamoDB has grown significantly since its launch. While AWS will not release customer figures, company engineer James Hamilton said in November that DynamoDB has grown 3x in requests it processes annually and 4x in the amount of data it stores compared to the year prior. Even with that massive scale and growth, DynamoDB has consistently returned queries in three to four milliseconds.

Below is a video demonstrating DynamoDB’s remarkably consistent performance even as more stress is put on the system.

To see a demo of DynamoDB, jump to the 16:47 mark in the video.
Feature-wise, DynamoDB has grown, too. NoSQL databases are generally broken into a handful of categories: Key-value store databases organize information with a key and a value; document databases allow full documents to be searched against; while graph databases track connections between data. DynamoDB originally started as a key-value database, but last year AWS expanded itto become a document database by supporting JSON formatted files. AWS last year also added Global Secondary Indexes to DynamoDB, which allow users to have copies of their database, typically one for production and another for querying, analytics or testing.

NoSQL’s use case and vendor landscape
The fundamental advantage of NoSQL databases is their ability to scale and have flexible schema, meaning users can easily change how data is structured and run multiple queries against it. Many new web-based applications, such as social, mobile and gaming-centric ones, are being built using NoSQL databases.

While Amazon may have helped jumpstart the NoSQL market, it is now one of dozens of vendors attempting to cash in on it. Nick Heudecker, a Gartner researcher, stresses that even though NoSQL has captured the attention of many developers, it is still a relatively young technology. He estimates revenues of NoSQL products to not even surpass half a billion dollars annually (that’s not an official Gartner estimate). Heudecker says the majority of his enterprise client inquiries are still around SQL databases.

NoSQL competitors MongoDB, MarkLogic, Couchbase and Datastax have strong standings in the market as well and some seem to have greater traction among enterprise customers compared to DynamoDB, Huedecker says.

Living in the cloud

What’s holding DynamoDB back in the enterprise market? For one, it has no on-premises version – it can only be used in AWS’s cloud. Some users just aren’t comfortable using a cloud-based database, Heudecker says. DynamoDB competitors offer users the opportunity to run databases on their own premises behind their own firewall.

Khawaja Shams, director of engineering for DynamoDB says when the company created Dynamo it had to throw out the old rules of SQL databases.

Shams, AWS’s DynamoDB engineering head, says because the technology is hosted in the cloud, users don’t have to worry about configuring or provisioning any hardware. They just use the service and scale it up or down based on demand, while paying only for storage and throughput, he says.

For security-sensitive customers, there are opportunities to encrypt data as DynamoDB stores it. Plus, DynamoDB is integrated with AWS - the market’s leading IaaS platform (according to Gartner’s Magic Quadrant report), which supports a variety of tools, including other relational databases such as Aurora and RDS.

Adroll rolls with AWS DynamoDB

Marketing platform provider Adroll, which serves more than 20,000 customers in 150 countries, is among those organizations comfortable using the cloud-based DynamoDB. Basically, if an ecommerce site visitor browses a product page but does not buy the item, AdRoll bids on ad space on another site the user visits to show the product they were previously considering. It’s an effective method for getting people to buy products they were considering.

It’s really complicated for AdRoll to figure out which ads to serve to which users though. Even more complicated is that AdRoll needs to decide in about the time it takes for a webpage to load whether it will bid on an ad spot and which ad to place. That’s the job of CTO Valentino Volonghi --he has about 100 milliseconds to play with. Most of that time is gobbled up by network latency, so needless to say AdRoll requires a reliably fast platform. It also needs huge scale: AdRoll considers more than 60 billion ad impressions every day.

AdRoll uses DynamoDB and Amazon’s Simple Storage Service (S3) to sock away data about customers and help its algorithm decide which ads to buy for customers. In 2013, AdRoll had 125 billion items in DynamoDB; it’s now up to half a trillion. It makes 1 million requests to the system each second, and the data is returned in less than 5 milliseconds -- every time. AdRoll has another 17 million files uploaded into Amazon S3, taking up more than 1.5 petabytes of space.

AdRoll didn’t have to build a global network of data centers to power its product, thanks in large part to using DynamoDB.

“We haven’t spent a single engineer to operate this system,” Volonghi says. “It’s actually technically fun to operate a database at this massive scale.”

Not every company is going to have the needs of Amazon.com’s ecommerce site or AdRoll’s real-time bidding platform. But many are struggling to achieve greater scale without major capital investments. The cloud makes that possible, and DynamoDB is a prime example.

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Saturday, 20 June 2015

20 best iPhone/iPad games

Star Wars Rebels, Fireworks, Shakespeare and lots of quests are featured in top iPhone and iPad games.

Games
As we head toward summer 2015, it’s time to check in and see how the mobile gaming industry has fared for Apple iOS platforms, the iPhone and iPad. Here’s a look at top rated games issued so far this year, based on App Store user reviews and professional reviewers on Metacritic. We hope you’ll discover a few hidden gems in here.

Legend of Grimrock
Developer: Almost Human
Price: $5
Ratings: 95 of 100 on Metacritic; 4.5 of 5 stars on Apple App Store; Ages 9+

This popular role-playing game for the PC brings its dungeon crawling to iOS. With Legend of Grimrock, enable prisoners who may or may not have committed the crimes for which they’ve been exiled to Mount Grimlock navigate its maze of tunnels and tombs.

Ryan North’s To Be or Not to Be
Developer: Tim Man Games
Price: $6
Ratings: 93 of 100 on Metacritic; 4 of 5 stars on App Store; Rated 12+

Shakespeare meets the iPhone and iPad in Ryan North’s To Be or Not to Be game. As the developer writes: “Play as Hamlet and revenge your father's death. Play as Ophelia and make scientific discoveries. Play as King Hamlet, Sr. and die on the first page!”

Implosion: Never lose hope
Developer: Rayark
Price: $10
Ratings: 93 of 100 on Metacritic; 4.5 stars on App Store; Rated 12+

Implosion transports you here: “Twenty years after the fall of Earth, the remnants of the Human race are once again faced with extinction. The time has come to justify our existence. A mysterious life form known as the XADA squares off against humanity's last weapon - the War-Mech series III battle suit.”

Attack the Light: Steven Universe Light RPG
Developer: Cartoon Network
Price: $3
Ratings: 91 of 100 on Metacritic; 5 of 5 stars on App Store; Rated for ages 9+.

Attack the Light is a role-playing game in which 4 heroes team up for a magical adventure.

Sorcery! 3
Developer: Inkle Studios
Price: $5
Ratings: 90 of 100 on Metacritic; 4 of 5 stars on App Store; Rated 12+

Sorcery! 3 is described as “An epic adventure through a cursed wilderness of monsters, traps and magic.” And you don’t need to have played parts 1 or 2.
Video courtesy YouTube.com

Does not Commute
Developer: Mediocre AB
Price: Free
Ratings: 87 of 100 on Metacritic; 4.5 of 5 stars on App Store: Rated ages 4+.

In Does not Commute, “What starts out as a relaxing commute in a small town of the 1970s quickly devolves into traffic chaos with hot dog trucks, sports cars, school buses and dozens of other vehicles. You drive them all.”

Magic Touch: Wizard for Hire
Developer: Nitrome
Price: Free
Ratings: 87 of 100 on Metacritic; 4.5 of 5 stars on App Store; Rated age 9+.

In Magic Touch a wizard is wanted who has proficiency in spell casting for popping intruders’ balloons.

Halo Spartan Strike
Developer: Microsoft
Price: $6
Ratings: 86 of 100 on Metacritic; 4.5 of 5 stars on App Store; Rated for ages 12+.

In Halo Spartan Strike, you are a supersoldier tasked with up to 30 challenging missions in city and jungle settings. Don’t worry, you have plenty of weapons, skills and vehicles with which to pummel and outwit enemies of Earth.

SwapQuest
Developer: Constantin Graf
Price: $3
Ratings: 85 of 100 on Metacritic; 3.5 of 5 stars on App Store; Rated for ages 9+.

SwapQuest mixes easy-to-learn puzzles with role-playing action as you try to save the Kingdom of Aventana from a demon cloud dubbed the Horde.

Silly Sausage in Meatland
Developer: Nitrome
Price: Free
Ratings: 85 of 100 on Metacritic; 4.5 of 5 stars on App Store; Rated for ages 9+.

In Silly Sausage you’re a dog with an infinitely stretchy body, which can be handy but also exposes you to all sorts of meat cutting instruments.

Card Crawl
Developer: Arnold Rauers
Price: $2
Ratings: 84 of 100 on Metacritic; 5 of 5 stars on App Store; Rated for ages 12+.

Card Crawl is solitaire with a dungeon crawler twist, in which you need to say monsters efficiently.

TouchTone
Developer: Mikengreg
Price: $3
Ratings: 84 of 100 on Metacritic; 4 of 5 stars on App Store; Rated ages 12+.

TouchTone is a game that the likes of the NSA and Anonymous would love: decrypt suspicious messages to make the nation safer and stronger.

Flop Rocket
Developer: Butterscotch Shenanigans
Price: Free
Ratings: 84 of 100 on Metacritic; 4.5 of 5 on App Store; Rated for ages 12+.

Next best thing to flying a drone: “Pilot your Flop Rocket through a 5 kilometer cave filled with dragon-like Spaceducks, enormous rock-worms, and other space-time anomalies as you try to prevent an underfunded space program from going bust.”

Fearless Fantasy
Developer: TinyBuild
Price: $4
Ratings: 84 of 100 on Metacritic; 4.5 of 5 stars on App Store; Rated for ages 9+.

Fearless Fantasy is a gesture-based role-playing game in which you are a bounty hunter intent on slaying weird creatures and saving a young woman from an awful marriage.

The Quest Keeper
Developer: Tyson Ibele
Price: Free
Ratings: 83 of 100 on Metacritic; 4.5 of 5 stars on App Store; Rated for ages 4+.

In The Quest Keeper, your mission is to help a peasant become a dungeon master, but you’ll need to dodge spikes, knives and scary creatures to do so.

Star Wars Rebels: Recon Missions
Developer: Disney Interactive Studios
Price: Free
Ratings: 83 of 100 on Metacritic; 4.5 of 5 stars on App Store; Rated for ages 9+.

Star Wars Rebels is based on the TV show, and lets you take on the Empire in this action platform game.

Blokshot Revolution
Developer: Foxhole Games
Price: Free
Ratings: 82 of 100 on Metacritic; 4.5 of 5 stars on App Store; Rated for ages 4+.

In Blokshot Revolution, experience “a beautiful firework display of hypnotic neon destruction” set against a pumping EDM sountrack.

Beast Quest

Developer: Miniclip.com
Price: Free
Ratings: 81 of 100 on Metacritic; 4 of 5 stars on App store; Rated for ages 9+.

The Beast Quest action-adventure game asks whether you are the hero Avantia has been looking for to free the magical beasts of this leand from the spell of a wicked wizard.
best iphone ipad games 20

Marvel Future Fight
Developer: Netmarble Games
Price: Free
Ratings: 81 of 100 on Metacritic; 4.5 of 5 on App Store;

This Marvel role-playing game lets you assemble teams of super heroes for single or multiple player games, as you battle via weapons and skills to keep humanity alive.

MicRogue
Developer: Crescent Moon Games
Price: $2
Ratings: 80 of 100 on Metacritic; 2 of 5 stars on App Store; Rated for ages 4+.

MicRogue does have a weak rating on the App Store based on limited reviews, but Metacritic reviewers gave it some love for packing fun into a small package. Climb a dark tower and avoid monsters with chess-like moves.

Tuesday, 9 June 2015

CompTIA Network+ Exam Code N10-006

CompTIA Network+ Exam Code N10-006
Network+ Certification Network+ is an ISO-17024 compliant, vendor-neutral technology certification that verifies the certified individual has the skills and knowledge needed to take on a pivotal role in building, managing, and protecting the critical asset that is the data network.

Recommended as a first professional-level networking certification
Held by nearly half a million people worldwide
12% job growth expected for Network & Computer Systems Administrators (2012 – 2022, according to the BLS
The leading vendor-neutral, globally-recognized networking certification
ISO 17025 compliant
Fulfills US DoD Directive 8570.01-M
 
Jobs that use Network+

Network Administrator
Network Technician
Network Installer
Help Desk Technician
IT Cable Installer
Keeping the world connected
Network+ helps IT Professionals around the world advance their careers. Don't just take our word for it. See for yourself in this 2 minute video.

A new version of Network+ (N10-006) will launch on February 28, 2015. The new exam has been updated to reflect the current thinking of industry professionals as well as to reflect technologies used today, with a greater emphasis on practical knowledge, especially how to identify and use elements of a network infrastructure. Significant changes include:

Additional IPv6 concepts.
Emphasis on troubleshooting.
Additional security knowledge.
Knowledge of how to administer key systems.

The main differences between CompTIA Network+ N10-005 and Network+ N10-006 are the following:
Updated terms and technologies in the IT networking field.
More hands-on experiences such as installing, configuring, implementing, managing and troubleshooting.
Three new topics:
Compare and contrast physical security controls.
Summarize basic forensic concepts.
Summarize safety practices.

Companies such as Dell, HP, Ricoh, Sharp and Xerox recommend or require CompTIA Network+ for their networking technicians. It is also a technical prerequisite option for IT technicians seeking to join the Apple Consultants Network, and is recognized by the U.S. Department of Defense.

The CompTIA Network+ce program is included in the scope of this accreditation, and may be kept current through the CompTIA Continuing Education program.

Test Details
Exam Codes N10-005
JK0-019 (for CompTIA Academy Partners only) N10-006
JK0-023 (for CompTIA Academy Partners only)
Launch Date 1-Dec-11 28-Feb-15

Number of Questions Maximum of 100 questions Maximum of 90 questions
Type of Questions Multiple choice and performance-based

Passing Score
720 (on a scale of 100-900)

Recommended Experience
CompTIA A+ Certification (9) months of networking experience

Languages English, Japanese, German, Simplified Chinese, Korean, Spanish, Traditional Chinese
English at launch (2/28/15) Japanese and German - in development







QUESTION 1
A technician has verified that a recent loss of network connectivity to multiple workstations is due
to a bad CAT5 cable in the server room wall. Which of the following tools can be used to locate its
physical location within the wall?

A. Cable certifier
B. Multimeter
C. Cable tester
D. Toner probe

Answer: D

Explanation:


QUESTION 2
Which of the following is used to authenticate remote workers who connect from offsite? (Select
TWO).

A. OSPF
B. VTP trunking
C. Virtual PBX
D. RADIUS
E. 802.1x

Answer: D,E

Explanation:


QUESTION 3
Which of the following network infrastructure implementations would be used to support files being
transferred between Bluetooth-enabled smartphones?

A. PAN
B. LAN
C. WLAN
D. MAN

Answer: A

Explanation:


QUESTION 4
Which of the following would be used in an IP-based video conferencing deployment? (Select
TWO).

A. RS-232
B. 56k modem
C. Bluetooth
D. Codec
E. SIP

Answer: D,E

Explanation:


QUESTION 5
Which of the following helps prevent routing loops?

A. Routing table
B. Default gateway
C. Route summarization
D. Split horizon

Answer: D

Explanation:


QUESTION 6
Which of the following is MOST likely to use an RJ-11 connector to connect a computer to an ISP
using a POTS line?

A. Multilayer switch
B. Access point
C. Analog modem
D. DOCSIS modem

Answer: C

Explanation:


QUESTION 7
An administrator has a virtualization environment that includes a vSAN and iSCSI switching.
Which of the following actions could the administrator take to improve the performance of data
transfers over iSCSI switches?

A. The administrator should configure the switch ports to auto-negotiate the proper Ethernet
settings.
B. The administrator should configure each vSAN participant to have its own VLAN.
C. The administrator should connect the iSCSI switches to each other over inter-switch links (ISL).
D. The administrator should set the MTU to 9000 on the each of the participants in the vSAN.

Answer: D

Explanation:


QUESTION 8
A network topology that utilizes a central device with point-to-point connections to all other devices
is which of the following?

A. Star
B. Ring
C. Mesh
D. Bus

Answer: A

Explanation:


QUESTION 9
A technician is connecting a NAS device to an Ethernet network. Which of the following
technologies will be used to encapsulate the frames?

A. HTTPS
B. Fibre channel
C. iSCSI
D. MS-CHAP

Answer: C

Explanation:


QUESTION 10
The network install is failing redundancy testing at the MDF. The traffic being transported is a
mixture of multicast and unicast signals. Which of the following would BEST handle the rerouting
caused by the disruption of service?

A. Layer 3 switch
B. Proxy server
C. Layer 2 switch
D. Smart hub

Answer: A

Explanation: