GTT on Wednesday commenced the drawing of its “Valentine Mashment Promotion” at the Blackberry Office, Brickdam, in which 70 customers were winners of many colourful costumes.Representatives of GTT conducting the drawingThis Promotion is also in light of the company’s 23rd anniversary celebrations. The 70 persons who purchased unlimited data plans were the recipients of these costumes and would be featured in the company’s costume float parade contingent, which is themed “Amazon Gems”. They are expecting to see a huge turnout of approximately 400 persons.GTT Public Relations Officer (PRO) Nadia De Abreu, when asked about the celebrations, stated that it has been a while since the company has participated in the Mashramani parade, so this would be a big comeback. This is also the company’s gesture of giving back to valued customers and providing them with an unforgettable experience.There are many ongoing and scheduled activities slated for this period in which persons can get a chance to win costumes and participate in the GTT Mash band. There is an ongoing fitness campaign on Mondays, Wednesdays and Fridays at the Everest Cricket Club Ground that will conclude on February 21, with the fitness finale.“Activation giveaways” were also conducted, in which 20 persons who applied for service during the anniversary period also won costume prizes. The number of combined winners from these promotions will add up to over 90 winners. There will also be a limited number of costumes available at Pulse Entertainment, who has partnered with GTT and online, for those who would like to be part of the company’s float.
0Shares0000Double for Mane: Sadio Mane scored twice for Liverpool against Newcastle © AFP / Paul ELLISLiverpool, United Kingdom, Sep 14 – Sadio Mane and Mohamed Salah ensured Liverpool maintained their 100 percent start to the Premier League season by coming from behind to beat Newcastle 3-1 at Anfield on Saturday.The European champions have a history of starting slowly in early kick-offs under Jurgen Klopp and only arose from their slumber after the Magpies took a shock lead through Jetro Willems on seven minutes. Mane turned the tide before half-time with a sumptuous finish into the top corner before profiting from an error by Newcastle goalkeeper Martin Dubravka for his second.Dubravka redeemed himself after the break with a string of fine saves to keep the final score down, but was helpless when Salah finished coolly from Roberto Firmino’s cute backheel.Klopp’s men open up a five-point lead over Manchester City at the top of the table, but the champions can cut that gap back to two with victory at Norwich later on Saturday.Newcastle sprung a huge surprise by claiming their only win of the season so far at Tottenham three weeks ago. They followed the same script as they frustrated the hosts in the early stages before stunning Anfield by going in front.Willems turned inside Trent Alexander-Arnold before drilling a fierce shot past the helpless Adrian.– ‘Need to start quicker’ –“We didn’t start the game the way we wanted to and to be fair to Newcastle they started brightly and scored a hell of a goal,” said Liverpool defender Andy Robertson. “That gave us the wake-up call we needed and afterwards I think we kicked into gear and were too good for them.“We need to be quicker getting back into our rhythm (after international breaks) or against teams in the top six we might struggle to get back into the game if we give away a goal.”Liverpool trailed at home for the first time since March, but quickly rallied to record a 14th straight Premier League victory.Mane was furious with Salah after being substituted in a 3-0 win away to Burnley before the international break, accusing the Egyptian of being too greedy in his eye for goal.But Salah suggested any feud had been forgotten before kick-off by posting a doctored video with the two players’ faces superimposed onto a viral video of two boys hugging.And Mane was certainly in a happier mood once he equalised by arrowing into the far corner from Robertson’s pass to get Liverpool back on level terms.Firmino had been rested from the start after travelling to the United States with Brazil during the international break, but he was soon called into the action as Divock Origi limped off injured.And he made an instant impact as his pass forward was spilled by Dubravka for Mane to roll into an empty net.Liverpool had only one scare once they were in front as Emil Krafth blasted over a great chance to bring Newcastle level again at the back post.However, it was only a matter of time before the Reds made the game safe as Dubravka saved brilliantly from Robertson and twice denied the excellent Firmino, who was named man-of-the-match despite only coming on eight minutes before half-time.“We were relieved when he was on the bench but then he came on and made all the difference,” said Newcastle manager Steve Bruce.“Liverpool were just incredible in the second half. It was just attack after attack. Firmino drops into those areas that no one else can.”The Brazilian bagged another assist when his flick freed Salah, who took his time before leaving Dubravka grounded and placing the ball into the far corner.Mane was denied his hat-trick and Firmino a triple of assists by the offside flag, but Liverpool cruised through the final stages with one eye already on the start of their defence of the Champions League away to Napoli on Tuesday.0Shares0000(Visited 9 times, 1 visits today)
7 By the way, if you’re wondering where the rest is, I hand wash it all. I’m domesticated. I won’t be hanging anything out to dry in this though! 7 Back to base, sorted my washing, and took extra measures to avoid another ‘laundrygate’ episode (they lost my washing last week, and only found it four days later). I took photos of what’s in the laundry bag – if they lose this one there will be trouble. Fingers crossed…. And what do you make of the marks for England 2 Wales 1 – harsh on Ashley Williams possibly? Throughout Euro 2016, our main in the England camp, Adrian Durham, will be sharing his thoughts in a daily diary. Here’s the latest instalment…Went for brunch at L’Etrier café next door to the England team hotel. The owner is a surly so and so, but his croque madame is something to savour. Ham and cheese toastie with egg on top. Oh, my days, it is so good. 7 Roy Hodgson and his staff emerged form the hotel while we were there, and made their way to training on foot. Roy looked cool in shades, relaxed after victory obviously, but you can see the photographers were hot on his heels ready for their big picture. Halfway up the street he was walking along, there is an “erotic” shop, (Yes! In sleepy Chantilly!) I’m guessing they think the “money” shot is that one – “England manager outside Sex Shop.” 7 Read Adrian Durham’s Euro 2016 diary every day 7 7 All washed down with café au lait while reading L’Equipe (well, looking at the pictures anyay!) and life is sweet.L’Equipe give marks out of 10 for the games at the Euros, and they are notoriously low markers. Check out how understated they were about Northern Ireland’s magnificent display in Lyon! 7 Then I set to work on the two games I was covering on Friday afternoon (Saggers hosts only one – is it because I’m younger? Not sure….), before a big night out in Paris beckons. And it will be a big night out because I am off on Saturday, which will serve as some much-needed recovery time.
Some of Ireland’s biggest acts have been announced for Letterkenny Live this summer.The event, which takes place on August 18th and 19th, will feature none other than Bressie and also the legendary Aslan. Details of the super event were announced at a launch last night.Among those at the launch was Letterkenny Chamber CEO Toni Forrestor, Town Mayor Gerry McMonagle and President of the Chamber John Watson.Speaking on behalf of the Letterkenny Live Committee, Toni Forrester acknowledged the financial contribution and support they have received from Letterkenny Town Council “This year the council included Letterkenny Live in their 2012 budget and gave us double that of last year. We have also received funding from Donegal County Council Development Fund Initiative and Failte Ireland. This substantial public funding really makes the difference in being able to plan the festival with confidence.”Toni went on to thank the local publicans who have come on board as sponsors and pledged their wholehearted support. “In the current climate every cent counts and these businesses have shown their commitment to Letterkenny Live and to Letterkenny. So far we have support from The Cavern, Voodoo & Ink, McGinleys who came on board last year.“In addition we have secured support from The Pulse and The Orchard Inn who are keen to get involved this year. All of these combined will give us the financial stability we need but also help make it a town wide festival. All of these entertainment venues will also be organising events throughout the weekend to give the town a festival feel.“We have also been promised financial support from other local businesses and we have been offered in kind from The Station House Hotel, Browne Printers, Greenlight Media who are looking after our website, Watson Hire. We’re confident that over the next few weeks we’ll garner the further support financially and otherwise that we need to make the 2012 event even more successful”.Letterkenny Live is run by a small voluntary committee who have been working hard all year to get us to this point.The committee comprises: Ciaran Martin, Town Council; Siobhan Barrett Doherty, Station House Hotel; Darren Browne, Browne Printers; Jimmy McGinty, The Cavern; Pauric Hilferty and Gavin McDaid, Greenlight Media, Cllr.Jimmy Kavanagh and Cllr Gerry McMonagle. The team all have day jobs and were delighted with last year’s achievement and are looking forward to this year’s line up.Letterkenny Live is happening on Saturday 18th & Sunday 19th August. The stage will be located on Oliver Plunkett Road. Both nights kick off at 7.30pm and will finish at 11pm, early enough for families and young people to get home and for others giving plenty of time to visit local pubs and clubs who are already planning festival events for after the show. On Saturday Night the headline act is bressie well known from The Voice supported by Aslan and Kanyu Tree. Both are fantastic festival bands that have a wide appeal.“This year to give it more of a festival feel we’ve partnered with Donegal Youth Service who will deliver their annual Party in The Park on Saturday afternoon. This annual event is a real showcase for local young bands and attracts upwards of 1000 young people each year. This year they have re-named it Party in The Car Park. They will have access to the full set up and we’re delighted to be able to add this to our lineup from 1.30pm to 5.30pm,” added Toni.Sunday is Country Night with Susan McCann, supported by Hugo and Off the Kuff and Trevor Loughrey. All really popular acts that will create a different type of concert but one we think will be really appealing to a wider audience.The Mayor, Gerry McMonagle, speaking at the Launch said “this years line up looks bigger and better than last year. The Council are pleased to support this initiative financially and practically and hope that it will attract visitors and local people to create a great on street festival each and every year in Letterkenny.” The website is www.letterkennylive.ie is live, follow Letterkenny Live on Facebook and @letterkennylive on Twitter.BRESSIE AND ASLAN AMONG LINE-UP FOR LETTERKENNY LIVE! was last modified: May 28th, 2012 by StephenShare this:Click to share on Facebook (Opens in new window)Click to share on Twitter (Opens in new window)Click to share on LinkedIn (Opens in new window)Click to share on Reddit (Opens in new window)Click to share on Pocket (Opens in new window)Click to share on Telegram (Opens in new window)Click to share on WhatsApp (Opens in new window)Click to share on Skype (Opens in new window)Click to print (Opens in new window)Tags:Letterkenny Live
Share Facebook Twitter Google + LinkedIn Pinterest Leave a Comment The Ohio State Fair Sale of Champions livestock auction, held Sunday afternoon Aug. 5 in the WCOL Celeste Center, showcased Ohio’s premium livestock, premier junior fair exhibitors and generous supporters. On the sale bill were grand champion and reserve champion of many species, including market beef, market barrows, market lambs and market chickens, as well as the grand champion market goat, market turkey and a block of Swiss cheese to represent the seven dairy champions. In full, the livestock was auctioned for a total of $255,000.Ohio Farm Bureau and Bob Evans Farms, Kale Marketing, Ohio Harness Horsemen’s Association, Event Marketing Strategies and Huffman’s Market purchased the Reserve Grand Champion Market Barrow for $33,000, setting a new state fair record with the purchase.“We wouldn’t have such a successful Sale of Champions if it weren’t for our talented and dedicated youth and our incredibly supportive buyers. Our Youth Reserve Program is very impactful to not just those in the Sale of Champions but for everyone involved in the youth organization. It is such an honor to reward everyone involved,” explained General Manager Virgil Strickler. “We are exceptionally pleased with the $167,000 raised for the Youth Reserve Program at today’s Sale of Champions.”While these Junior Fair exhibitors take great pride in raising a quality animal, the ultimate goal each year is to be awarded a grand champion ribbon. Grand or reserve champion is an immense honor for the exhibitor; and with the Youth Reserve Program and generous buyers, it is rewarding for the entire Junior Fair program. This year’s sale broke two records: Reserve Grand Champion Market Barrow, which sold for $33,000, and Grand Champion Swiss Cheese, which sold for $28,000.Established in 1995, the Youth Reserve Program’s was developed to reward junior exhibitors who participate in the Ohio State Fair. Funds for the program come from the dollars received over a cap that is placed on the amount an exhibitor can receive from the Sale of Champions. The funds from the program are distributed among carcass contests, scholarships, outstanding market exhibitor program, outstanding breeding exhibitor program, showmanship, skillathons, 4-H and FFA. The Youth Reserve Program has awarded $3,366,815 to approximately 40,000 youth exhibitors since its inception.The 2018 Sale of Champions results are as follows:Grand Champion Market Beef Exhibited by: Caden Jones, Allen CountyPurchased by: Steve R. Rauch, Inc.Price: $41,500Cap: $22,000Reserve Grand Champion Market Beef Exhibited by: Carver Gostomsky, Darke CountyPurchased by: The Kroger CompanyPrice: $20,000Cap: $11,000Grand Champion Market Barrow Exhibited by: Matthew Butterfield, Butler CountyPurchased by: MeijerPrice: $48,000Cap: $10,000*Reserve Grand Champion Market Barrow Exhibited by: Grant Adams, Mercer CountyPurchased by: Bob Evans Farms, Kale Marketing, Ohio Harness Horsemen’s Association, Ohio Farm Bureau, Event Marketing Strategies and Huffman’s MarketPrice: $33,000*Cap: $7,000Grand Champion Meat Chickens Exhibited by: Allison Davis, Carroll CountyPurchased by: The Kroger Company, Gerber PoultryPrice: $14,000Cap: $6,000Reserve Champion Meat Chickens Exhibited by: Meghan O’Reilly, Geauga CountyPurchased by: The Kroger Company, Gerber PoultryPrice: $10,000Cap: $4,000Grand Champion Market Lamb Exhibited by: Grant Johnson, Wayne CountyPurchased by: The Kroger CompanyPrice: $21,000Cap: $10,000Reserve Grand Champion Market Lamb Exhibited by: Bailee Amstutz, Union CountyPurchased by: Steve R. Rauch, Inc.Price: $14,000Cap: $7,000Grand Champion Market Goat Exhibited by: Ava Shroyer, Logan CountyPurchased by: The Kroger CompanyPrice: $11,000Cap: $5,000Grand Champion Market Turkey Exhibited by: Myah Jones, Clinton CountyPurchased by: Kale Marketing, Ohio Harness Horsemen’s Association, Cooper Farms, and RD Jones ExcavatingPrice: $14,500Cap: $3,000*Grand Champion Swiss Cheese, produced by Pearl Valley Cheese Co., representing the seven dairy champions and supreme dairy showmenExhibited by:Grand Champion Ayrshire: Marissa Topp, Auglaize CountyGrand Champion Brown Swiss: Keaton Topp, Shelby CountyGrand Champion Guernsey: Abigayle Dicke, Mercer CountyGrand Champion Holstein: Kristopher Ackley, Logan CountyGrand Champion Jersey: Drake Tompkins, Morgan CountyGrand Champion Red and White: Madeline Topp, Auglaize CountyGrand Champion Milking Shorthorn: Aubree Topp, Shelby CountySupreme Showman, Week 1 – Exhibited by: Madelin Topp, Auglaize CountySupreme Showman, Week 2 – Exhibited by: Kinley Topp, Shelby CountyPurchased by: AG Boogher and Sons, S&S Volvo and GMC TrucksPrice: $28,000*Cap: $3,0002018 total sale: $255,0002018 amount earned for Youth Reserve Program: $167,000*Denotes new record Leave a Comment
Great info here on understanding how colors effect one another and how these principles can be applied in DaVinci nodes. See JuanMelara.com for more details on this Hollywood style color grading technique. Thanks for sharing this excellent tutorial, Juan![Best viewed full screen] Learn how to achieve a “Hollywood Blockbuster” color treatment in DaVinci Resolve. See some of the hit films that use this cool/warm color treatment and discover what node settings can be used to give your projects this look.Colorist and cinematographer Juan Melara takes and makes beautiful pictures. Luckily, he has decided to share his in-depth knowledge of color theory and practictal application with the rest of the ‘net.In his first color grading tutorial (below) Juan shares his recipe for creating a cool/warm color grading look popularized in Hollywood blockbuster movies. The video tutorial is expertly formatted, first showing a few films that utilize this technique (Mission Impossible, Battleship, Transformers), then going on to explain the color theory behind how the look is acheived. Lastly, Juan jumps into DaVinci Resolve and shows you how you can apply this grade to your own film and video projects.Trademarks of the Hollywood Blockbuster style color grade include:Cool, blue and teal backgroundsSkin tone seperation from the backgroundSkin tones appear warm and relatively natural
The authorities on Friday foiled a march called by separatists in Kashmir by placing parts of Srinagar and Anantnag under security restrictions.All Parties Hurriyat Conference (APHC) chairman Mirwaiz Umar Farooq, Tehreek-e-Hurriyat (TeH) chairman Syed Ali Shah Geelani and Jammu Kashmir Liberation Front (JKLF) chief Yasin Malik were either detained or placed under house arrest during the day. Security forces erected barricades in Srinagar and along the National Highway connecting the city with Anantnag. Train services were stopped in south Kashmir. No Friday prayers were allowed at the historic Jamia Masjid. “Why is the government choking our political activities if it believes in democracy?” the APHC chairman said.“Hundreds killed” The Mirwaiz alleged that “hundreds of people, mostly youth, have been killed in the ‘Operation All-Out’”.“The dictatorial approach of those in power is highly condemnable. The government has conceded its defeat by disallowing the rally,” the Mirwaiz added.
Former Pakistan captain Salman Butt claimed that the thousands of pounds of cash discovered by British police at his hotel room during spot-fixing investigation in late August was part of his legitimate tour allowances.Butt and pacemen Mohammad Asif and Mohammed Aamer were provisionally suspended by International Cricket Council following allegations of spot-fixing in a News of the World sting expose.The British tabloid had claimed that the Pakistani trio had conspired with London-based bookie Mazhar Majeed to bowl deliberate no-balls for money during the fourth Test against England at Lord’s in August.There were subsequent accusations that police had discovered USD 24,036 in marked notes in Butt’s hotel room.However, Butt said the wades of money were legitimate as they were tour allowances given to him by the Pakistan Cricket Board.”Well I think everybody knows the Pakistan Cricket Board pays us daily allowances on tours and it was a long tour,” he said in an excerpt of interview at his Lahore home with Sky Sports due to be broadcast later.”About 11,000 pounds of that money was from our daily allowances and being the captain I had an extra entertainment allowance which amounts to about 4,500 pounds from the tour, which I had with me,” said Butt.Butt’s case, and that of Asif and Aamer, will be heard by a three-man panel chaired by English lawyer Michael Beloff, who heads the ICC’s code of conduct commission, at a hearing in Doha, Qatar, next month.Butt said he is determined to resume playing professional cricket and his love for the game has not diminished despite the spot-fixing scandal.advertisement”The love of the game has got me there and that love is bigger than anything. I still remain positive and I know what I’m made of and where I’ve come from, and how I’ve played my cricket. Believe me, it has been a lot of passion all throughout my life,” he said.Asked if he was worried he would never play at the top level again, Butt said “I would certainly not like to think like that.”Butt also spoke about the support he’s received since spot fixing allegations came out in late August.With inputs from PTI
New Delhi, Sep 24 (PTI) Rahul Gandhi has gone to Aspen in U S to attend a conference and would be back much before campaigning in Bihar polls gets underway, Congress said today dismissing BJPs criticism of the tour of the party Vice-President. Reacting sharply to the BJP criticism, partys chief spokesman Randeep Surjewala said that it would be better for the BJP if it focused more on the poll tussle in Bihar rather than the visit to US of Gandhi. “With defeat in Bihar staring in the face like in Delhi, BJP is presenting Mohan Bhagwat with his anti-reservation statement while one day comes out with a new law for more reservation in Rajasthan…”, he claimed. The Congress leader insisted that the party Vice President has gone to the US to attend a conference Weekend with Charlie Rose at Aspen Institute in Colorado. BJP spokesperson G V L Narasimha Rao had earlier said that the Conference Gandhi was claimed to have gone to attend had got over in July and accused it of “resorting to falsehood to hide facts we dont know”. “Congress is unable to give proper reason for Rahuls absence. Everyday they are trotting out a new story, coming out with a new fact that turns out to be false. It is resorting to apparent falsehood and lies to hide facts we dont know,” he told reporters. Rao claimed the institutes manager had stated that nobody by the name of the Congress leader had either attended its event or was scheduled to take part in future. Rao said Rahul was entitled to go on a personal visit but Congress should stop “lying” to “mislead” the country. BJP and Congress are involved in a bitter war of words after the Congress leader left for the US, with the ruling party firing the first salvo derisively claiming he had been sent on a “forced vacation” as his Bihar allies believed that his presence would harm their chances in the assembly polls. Hitting back, Congress accused it of spreading “patent lies” and “petty canards” as BJP was foreseeing its “imminent loss” in the Bihar polls. “Rahul Gandhi is travelling to Aspen, US, on a short visit to attend a conference. Weekend with Charlie Rose is a conference where thought leaders from different walks of life like politics, finance, technology, media, medicine, sports gather to deliberate on multiple issues,” Surjewala had said. PTI SPG KR RGadvertisement
Leave a Reply Cancel reply You must Register or Login to post a comment. This site uses Akismet to reduce spam. Learn how your comment data is processed. With the rise of Bitcoin, corporate interest in the underlying blockchain technology has risen dramatically. Confusion arises, however, because much of the discussion centers on cryptocurrency, which is only one approach to using blockchain. To determine an approach that makes sense for the IoT, developers must first strip blockchain to its basics and build from there.Blockchain technology, essentially, provides a mechanism for a network of nodes to securely exchange information (called transactions) and mutually create a shared ledger documenting those transactions in a record that resists alteration. The basic process is simple, as shown in Figure 1 below. A node securely informs all the others of a transaction, which they validate and add to their list of pending transactions. At some point a “publishing node” creates a data block containing none, some, or all the pending transactions, which it presents to the network. When the nodes reach a consensus that the proposed block is valid they add it to their copy of the shared ledger and remove the corresponding transactions from their pending list.Each new block contains cryptographic links to the prior block added to the ledger, which in turn has links to its predecessor, continuing in an unbroken chain back to the first (genesis) block. The cryptographic links ensure that no block in the chain can be altered without detection, and the ledger’s many copies ensure there is no single point of failure that can destroy the ledger. Other mechanisms in blockchain’s technology ensure that all transactions get recorded, and that blocks linked to an incorrect copy of the ledger get rejected so that all functional copies of the ledger are identical. Figure 1 The essential operation of a blockchain is simple, but with many options available at each stage.While the overall operation of a blockchain implementation seems straightforward, there are many operational questions that must be resolved. How does a node join the network? What is the content of a transaction? How is it validated? Which nodes can publish a block? How often? What is its content? How do nodes reach a consensus on a block’s validity? What happens if there are several different blocks simultaneously awaiting validation? The blockchain developer’s answers to these questions will dictate their implementation’s operational effectiveness in its intended application. There are many options available for answering these questions; Bitcoin is simply one configuration of options developed for a cryptocurrency application and not even the only cryptocurrency blockchain.One place to start in defining a blockchain implementation for a specific application is to answer the question of how a node joins the network. There are essentially two types of blockchain network: permissionless and permissioned. A permissionless blockchain, also called a public blockchain, places no restrictions on what nodes can join the network and all nodes can participate in validation and consensus efforts. This results in a highly decentralized and redundant configuration. Bitcoin is a permissionless blockchain network.Permissioned networks, also called private blockchains, control what nodes can join, and which nodes are authorized to participate in validation and consensus. It is a less redundant and more centralized configuration than a public blockchain but can offer higher performance. Most enterprise and IoT applications of blockchain are likely to use permissioned network structures.Regardless of the blockchain network’s configuration, their blocks have a similar structure. Before a node announces a transaction, it encrypts that transaction using its private key to digitally “sign” the message. It may distribute its public key with the transaction so that the other nodes can validate accurate receipt of the transaction record or nodes may already have a copy of the key so that they can validate authorized messages as well as reject unauthorized messages. The transaction itself can contain virtually any kind of data, but often also designates both the source and the destination of the data transfer.One or more publisher nodes will combine a set of validated transactions into a block that is to be added to the chain and distribute the candidate block to the network. In addition to the transaction data, this block includes a header containing a cryptographic hash of the header from the prior block in the chain, a time stamp, and a cryptographic hash of the candidate block’s data. The header may also include a unique identifier called a nonce as well as other types of information the system may need. Figure 2 Each block’s header includes a cryptographic hash of the previous block’s header, thus creating a chain that cannot be altered without detection. (Source: NIST)Before a candidate block gets added to the chain, other nodes in the network must agree that it is valid, i.e., reach a consensus. Depending on the network configuration, nodes may not all participate in this consensus effort. In a blockchain designed for the IoT, for instance, there may be transaction-only nodes that do not maintain a copy of the chain or even other node’s transactions; they simply publish their data to the network. There may be lightweight nodes that keep copies of the headers only. Only full nodes, ones that validate and retain transactions, will retain a full copy of the blockchain. A full node may or may not be a publishing node, however, and may or may not participate in the consensus effort. The network’s configuration, especially that of a private blockchain network, determines which nodes take on what roles.The method by which nodes validate a candidate block – the consensus mechanism – is one of the areas where blockchain designers have considerable freedom but it can also involve considerable complexity. A basic problem with a distributed ledger is that, in practice, some of the nodes in the network will be untrustworthy and will deliberately or accidentally generate bad information that could contaminate the ledger. This is a particular risk in permissionless networks like Bitcoin; there are no impediments to a bad actor entering the network and plenty of incentive to “cook the books.” But even in a permissioned network there is a risk that one or more nodes will be untrustworthy.Fortunately, the attempt to reach a consensus on the validity of a block when some of the participants are trying to insert misinformation is a well-researched situation in information theory known as the Byzantine General’s Problem. Many consensus mechanisms have arisen from this research, but four major types are being used in most blockchain implementations: Proof of Work (PoW), Proof of Stake (PoS), Delegated Proof of Stake (DPoS), and the Practical Byzantine Fault Tolerance (PBFT) algorithms. Each has its strengths and weaknesses in terms of their ability to resist malign behavior, computational efficiency by publishers and full nodes, communications bandwidth requirements, and the like, but the first and fourth are particularly noteworthy.PoW is the consensus mechanism used in Bitcoin. Essentially it requires a publishing node to solve a cryptographic puzzle before creating its candidate block. The puzzle is to determine a nonce to include in the block’s header so that the hash of that header satisfies a specific condition, such as having at least so many leading zeros. Solving this puzzle is a computationally intensive effort (the work) involving many trials using randomly generated nonce values until a satisfactory result is obtained. Once a node that is working on the puzzle has found its “golden nonce” it can publish its candidate block. Other nodes can then readily validate the result by conducting their own hash of the block’s data to verify that element of the header, and then hash the reconstructed block header using the candidate nonce to verify that the conditions are satisfied. First candidate block to be verified by a majority of full nodes wins, and nodes will add that block to the blockchain.PoW functions as a secure consensus mechanism because the chances are exceedingly small that a bad actor can first alter the block data in a way that it generates the same data hash as the valid block data (a hash “collision”) and then generate a golden nonce for its corrupted block, before any other nodes can generate a valid block. It is so computationally intensive to generate a golden nonce, though, that Bitcoin provides an incentive to potential publishing nodes to ensure that they make the attempt. Such a publishing node (called a Bitcoin “miner”) will receive a payment (in newly minted Bitcoin) when it creates a block that wins the network’s agreement to add to the chain.The PoW consensus mechanism wastes a lot of processing power in its effort to keep bad actors from contaminating the blockchain, however. While this may be an acceptable expense when there are millions of dollars at stake to protect in a public blockchain, it is seldom cost-efficient for the kinds of private blockchains that the IoT will likely utilize. A much more computationally efficient approach suitable for the more controlled environment of a private blockchain is the PBFT algorithm, a variant of which is used in the Hyperledger Fabric available through the Linux Foundation as open source code.In the PBFT algorithm the network’s publishing nodes form an ordered sequence, with one of the nodes temporarily serving as the leading node, a period known as a “view.” During its view, the leading node publishes its candidate block along with a “pre-prepare” message that contains its identification and blockchain status. The remaining nodes must then validate that block by comparing the block’s header and data hashes and blockchain status with their internally-generated copies. Nodes then broadcast their acceptance or rejection vote on the block in a “prepare” message to all other nodes.When more than two thirds of the nodes report acceptance, each node then publishes a “commit” message acknowledging the successful vote and the node’s intent to add the block to its blockchain. When more than two thirds of the other nodes agree to commit, all nodes can go ahead and append the candidate block to their blockchain. Once a block has been successfully appended, the view changes and role of leading node moves to the next node in the sequence. Alternatively, if no consensus is achieved within a set time frame, nodes discard the candidate block, the view changes, and the next node in the sequence becomes the leading node to try again for consensus on a block. Figure 3 Message sequence and traffic for PBFT consensus algorithmWith the PBFT algorithm, the network can quickly identify and isolate nodes that misbehave, even if the leading node is the bad actor. If a node too frequently rejects valid blocks or fails to achieve consensus whenever it is the leading node, other nodes can learn to ignore it as faulty or malicious. In a permissioned network, the system can even include a supervisory algorithm that can permanently remove a misbehaving node from the network.This algorithm involves much less computation and executes much faster than the PoW approach because there are no puzzles to solve, only hashes to verify. Further, only one node at a time is authorized to publish candidate blocks, so there is no chance of an accidental “fork” in the chain that occur when different nodes adopt different (but valid) candidate blocks. Such forks can occur in Bitcoin due to the mining competition, should two successful candidates appear simultaneously, so Bitcoin must use additional algorithms to prune forks as they occur.The major disadvantage of PBFT is the amount of message traffic associated with consensus. Because each full node must send its pre-commit and commit messages to all the other nodes, message count scales exponentially. For an IoT implementation, however, this might not be a significant limitation.Consider a system in which several organizations (a consortium) mutually establish a permissioned blockchain network for tracking the handling of perishable goods requiring refrigerated storage and transport moving from source through warehouses to the final customer. Each handler (source, transportation provider, warehouse, distributor, retailer, etc.) maintains a publishing node for the blockchain. The end customer might also have a non-publishing node linked to the network for tracking the blockchain of their specific purchase.IoT sensors monitor the goods, regularly sending their location and temperature information to each stakeholder’s node for creation and maintenance of blockchains tracking the goods. The publishing nodes participate in a PBFT consensus mechanism in forming the blockchain that records the movement and temperature history of goods all the way from source to customer. The result is a blockchain that, should problems arise or proof be required, provides all parties with a consistent and immutable record of what happened.Such a network will not need a massive number of publishing nodes – only those stakeholders with contractual commitments to one another will require a consensus vote in maintaining the mutual ledger of the transactions. There may be other stakeholders that wish to maintain a copy, and so be connected to the network, but the traffic to them only scales linearly with the number of added nodes. A carefully-considered and well structured private blockchain using PBFT consensus thus can avoid bandwidth concerns.The trick, of course, is to choose a network structure, consensus mechanism, communications scheme, block and header definition, and other such details to fit the blockchain’s operation to the application’s needs. There are many possible implementations, some of which are commercially available from blockchain-as-a-service (BaaS) providers such as Amazon, IBM, Microsoft, and others. There is also open-source software, such as the Hyperledger Project, available to those seeking to develop a custom blockchain implementation.At its most abstract, blockchain technology allows the creation and maintenance of a distributed, tamper-resistant, digital transaction record. This record is open to inspection by interested parties, but not alterable by them. Even though the transactions are viewable, the parties involved in the transaction may, depending on the blockchain’s configuration, be anonymous or identifiable. Properly configured and applied, a blockchain can help increase the trust in and efficiency of IoT interactions.Rich Quinnell is an engineer, writer, and Global Managing Editor for the AspenCore Network. >> This article was originally published on our sister site, EDN: “Basics of blockchain for the IoT.” Continue Reading Previous SEGGER supports Hilscher multiprotocol SoC “netX90” to J-Trace and J-LinkNext Hyperledger Project resources for developers Share this:TwitterFacebookLinkedInMoreRedditTumblrPinterestWhatsAppSkypePocketTelegram Tags: Advanced Technology