Since i highly underestimated the amount of work and potential stress of a groupbuy i decided i will create a post for everyone who goes with the thought of starting a groupbuy on its own. I will describe what you have to await so you see this more correctly.

Firstly, i started a groupbuy for avalon asic chips Generation 1. Our groupbuy bought 5.6 batches, totaling 4816BTC. We had exactly 300 members involved.

The first thing i thought is that it wont be much work. The biggest work will be the packaging of the chips. Highly wrong. In fact the packaging is something that can be done in a couple hours. Which is a tiny fraction, not even worth to mention. But a groupbuy will mean to you work of 2-6 hours each day, 7 days a week and for me now unbelievable 4 months long (didnt notice this till now). Very seldom only 1 hour a day. You have to stay in contact with your groupbuyers. Nothing is worse for the situation than a groupbuy organizer that doesnt get back to the members. You can await that very fast rumours appear and fears lead to a doom loop that goes in a direction no one wants. Im sure you saw such groupbuys already since there are groupbuys of all kinds on bitcointalk.

Saying that... support is the biggest part of work. Up to 100 pm's each day are common most of the time, if nothing happens for some days you might only get around 20 a day but its seldom. Luckily i can type machine so im fast writing. If you cant it might take you even more time.

You need to be able to maintain a correct dataset. In my case i used a calc sheet of open office. Calc can greatly lower your work amount with automatic formulas and so on. For example i let calc create automatically forum topic, status text and order tables in bbc-code. It would have been a hell of a lot more work otherwise without this help.
Keep sure this data is protected. Backups is something you need very much since you deal not with your own money, its others people money. Even when you dont make backups for your own, at this point you have to when you dont want to risk real trouble.

Before starting a groupbuy make a set of rules. Its easier for you when you can point to explainations this way and it makes the rules clear for both side. The same goes for the fee you take, shipping cost and so on.

You need to specify refund rules. This topic will appear for sure and you need to be prepared. And according to my experience it might happen that everything stops for a reason you cant change and everyone wants his bitcoins back. Its best you have a rule prepared for that case so that you dont sit on the costs and work you had.
If something goes wrong (miner arent worth much anymore because of difficulty rise, seller did something wrong) and you werent fully in contact then await to be the one that was the reason for the problems. My members didnt say that luckily and i constantly was in contact but there might be others outside of the groupbuy that dont bother if you did it. Be prepared to be the one that lured them into buying and planned everything to scam in order to earn money. They simply search a scapegoat because some people cant simply search the error in their decision. It probably cant be changed since you cant be everywhere in each forum thread. So better stay in touch to prevent the doom loop i mentioned above. You dont want get this developed in a shitstorm without real base.

Important point... dont underestimate the legal problems. If as private groupbuy or as a business, the rules are different but there are possible problems that can really make you trouble in real life. Keep sure you thought everything through. I wont go into detail though. In case you want to start a groupbuy and want to know what i mean ask me via pm.

If youre unlucky you have a seller that isnt communicating. That doesnt only bring you much stress because you are the connection between your members and the seller. You get all the possible anger so you can transfer it to the seller. And what do you do when the seller isnt reacting? You collect this in form of stress. In my case i then started to try every way of contact and had to put a lot of time in it. At the end i had to give up realizing there wont be an answer.
I only want to warn you that this can happen.

It might get even worse. What if all was a scam? When the seller took the money and ran? Im not a lawyer but you better didnt do this as a company but instead as a private person that only ordered with its friends a bigger thing. Otherwise you would be the one taking all the loss. But like i said, im not a lawyer, maybe im wrong.
You might even think of rules regarding the case of scam happening. Its always better you have something to point at in case something unawaited happens.

Shipping, like i said, is something that doesnt really cost much time. I didnt ship the actual chips but many shipments with sample chips. Its not much time involved compared to the real time. You might use electronic stamps to speed up the process or similar things.
While we are at shipping. If its special hardware you need to make sure you can provide correct shipment. In my case buying pakets, antistatic bags, antistatic workplace to not hurt the chips, bubble foil and more. Be prepared since most probably time isnt something you will have much when the products were delivered to you.
I had to search a import company to solve some potential problems. To make sure that it will run correctly i travelled to the company and signed a contract to make sure i dont risk the bitcoins of other people because otherwise it would have been my problem.
I only say this to tell that such unawaited things happen too.

Next thing is information collecting. In case you need more infos, for example email, billing address, refund yes or no and so on, you have to collect them to move on. I had to do this several times. If you need that info its not enough to make a post. The response will be very low. You need to create pm. You can send 20 pm with one pm. For example let calc create you ready made lines like "username", "username2", that you can copy into BCC(Blindcopy)-Field so that no other member see the other receivers in case you offered anonymity of some kind. Theres a 120 PM limit per hour at the moment. Only if you do this you can hope to get the needed info in the next days. But even then you will miss 25%. Those remaining infos can come in slowly in weeks or months for mostly good reasons. Sometimes you dont get it at all.
But you will have again much work with it. Especially when you need the info to move on and have to remind often.

My personal result of the groupbuy i did is... my wall to break to do something like that again is huge. The reward is not even close to the stress and work that has to be done. Its really a full time job like someone said before. Luckily i was able to stop my normal work for other reasons, so i found this time. It would have been not be possible for me to do this properly otherwise.
A good result is on the other hand that people learn to know you. After you did this they know if youre trustworthy. Since trust is everything in bitcoin + the Net this is something valuable for sure.

I hope i could help someone with my experiences who thinks about making a groupbuy. Wink

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First off, not having to ask that question. You need to know some programming, C++, java, python. Read this https://bitcoin.org/bitcoin.pdf That should be enough to figure it out. Here is another cool article about it for beginners https://medium.com/@lhartikk/a-blockchain-in-200-lines-of-code-963cc1cc0e54

You need to know how to program, you don't need to know all of the above languages. That's pure overkill. I've never used Python or Java for anything, I do however use C for some things and some other higher level cross platform GUI tools for desktop front ends. Ultimately a lot of languages (at least the ones I use) produce programs which are built with the LLVM backend.

Crypto libraries like mbedTLS and LibSodium are written in C but that doesn't mean you need to write the rest of your programs in C or C++ with the Qt environment like Bitcoin.

The basic libs can be used in combination with various modern and very simple to use languages.

There are higher level languages which allow you to use the exact same cryptography as Bitcoin or similar ECC variations like Ed25519 instead of Secp256k1 for example.

You could for example write it in one of the .NET languages or something a bit more cross plaform friendly, there are some quite useful GUI enabled cross platform (Win, Mac and Linux) languages out there if you go looking for them and you can use as much or as little lower level C/C++ stuff as you want.

I would suggest that the first step will be to learn how to use the crypto libraries properly and take it from there.

Writing a blockchain based system is not a small job but it can be done if you're dedicated to the task and have enough time to do so.

What kind of blockchain utilising system did you have in mind ?

I'm interested in a minimalist private blockchain based system for what I'm working on, it doesn't need to be a coin but would use issued tokens to authorise database entries in a distributed manner which is hard to tamper with and is read only for nearly all users apart from those authorised to add blocks. These tokens would have no monetary value and certainly wouldn't be traded anywhere but would serve to enforce fair use of the system and prevent abuse by trusted users.

This is just a pet project of mine but as an emerging and relatively new way of doing things I'm sure there will be many interesting developments in the future so it's an area worth pursuing even if it takes a few years to get up to speed or produce anything worthwhile.

While I don't have a solid stance on raising the block size, I see a lot of roadblocks in the way of doing it.

    Raising the block size makes running a full node less accessible.
    Raising the block size requires a hard fork of the entire Bitcoin network, which imo would be extremely difficult.
    A lot of people are against it (/r/Bitcoin) just because other people have told them to be against it and haven't formed their own opinions, but are swept up in the tribalism


I also believe the lightning network will be successful. People may point at segwit and say "well segwit was supposed to help fees too, and we have low segwit adoption months after the soft fork". These people are correct, but they miss (imo) a huge point. Say a transaction fee on our congested network is $20. With segwit, that fee becomes ~$14 (roughly). With the lightning network, that fee becomes <$0.01. It's a massive, massive difference.

Say you have two choices: sell all your Bitcoins, because you believe Bitcoin is dead and can't properly scale. Alright, that takes 1 last transaction to move your coins to an exchange and sell them. OR, you could make one last transaction to open a lightning channel. Now, your Bitcoins are all available on the lightning network, where you can make instant, near-zero fee transactions.

I don't believe people will stop using the main network when people start shifting towards using the lightning network. But the more services that support the lightning network, the less payments will be made on chain, which frees up more room for people to make on chain transactions, transactions like opening more lightning network channels.

The battle that needs fought now (again, imo) is adoption of the lightning network. It's a drastic change from the benefits provided by segwit, which was more about fixing transaction malleability. If we could only fight one more battle, and it had to be raise the block size or get people to move over to the lightning network, the latter is going to work for a lot longer than the former. Because it's important which battles we choose here, because people will quickly get tired of needing to make changes to use Bitcoin.

Is there any project which is using blockchain technology in defence industry? I guess DAPRA is working for it but I'm not sure of that. If you know any project about that can you share here? And You think Why defence companies don't working for developing blockchain tech? They need cryptology and blockchain serving this. THX Wink

If they are working on that, they wouldn't make it public. These three letter agencies are very secretive, so if they created a blockchain, it would ultimately be a private blockchain which is not exciting because it's just a regular database more or less. What makes cryptocurrencies exciting is that they have to survive in the wild.

Intelligence agencies work on encryption and decryption mostly, on the actual algorithms, such as SHA-256, which bitcoin uses.
   

I can remember the days of totally free transactions.
Bitcoin (2009-2017✝) was intended for cheap transactions and micro-payments (P2P cash), you need something similar.

"I don't think the threshold should ever be 0.  We should always allow at least some free transactions." Satoshi Nakamoto.

I can sympathize with Satoshi's sentiment there, but he didn't build incentives for that into Bitcoin's design. The system relies on rational mining incentive: miners publish transactions because they are incentivized to mine for block rewards and collect the fees.

And for years, miners largely enforced node policy that reserved some space for "priority" transactions, including old coins sent with no fees. But miners are rational. When fee income became significant, they removed that node policy and started maximizing the fees they collect.

It's the mining incentive -- and therefore the protocol itself -- which resulted in this situation. This is the only way the system can guarantee block rewards in the future, once most of the 21 million coin supply is mined. And that's why Bcash will probably fail: when the block subsidy drops to zero, so will mining output, because fee income won't replace subsidy income.

Currently I run a program to estimate the lowest fee rate likely to get into the next block. It connects to my local Bitcoin core bode via RPC and runs getrawmempool. It sorts the transactions by fee rate, then takes off the top 1 MB worth of transactions. The fee rate of the last transaction to get in is, in my mind at least a good estimate of the required fee to get into the next block.

I am aware that this is a fairly naive approach, and I would like to improve it. Currently, it does not account for the SegWit discount and will incorrectly decide how many transactions will fit in the block. Also, I am not sure if looking at the mempool is the best option, maybe a rolling average of the lowest fee included in the past 3 blocks would be better for instance.

If these kinds of fee estimation questions have been asked before, feel free to link me but I wasn't able to find what I was looking for.

tl;dr How can I improve my simple fee estimation to be smarter?

When you look at latest blocks, you should check low-fee transactions for CPFP - they might be included in a block because their children compensated for low fee. Also, mining pools might include in blocks withdrawals of their members with lower fees, or they might include low fee transactions because they were paid through some other channels. So, you probably shouldn't expect that the lowest fee included in a recent block is safe enough to also get included in next few blocks - I'd raise that value by 10-20% to get some safer estimation.

Node discovery relays and some people argue that it cannot be done and it must be well complicated to calculate the
hops by the time you have to deal with fees and the reliability of intermittent nodes plus ensuring the nodes each have
sufficient balance in the ledgers to carry out the transaction.

I can only imagine the amount of code needed to make this happen so once again as was the case with mining coins
that lead on to CPU-Wars it seems to me like the solution is worse then the initial problem and from a performance
perspective this would be slow if hub/banks were all Alice, Bob, Peter and Paul

Every node for himself just to keep some academic dip sticks happy without more specialized nodes looks like a big mess
to me but if they want to proceed down this lightning route then maybe the need a cluster of routing servers (DNS Type thing)
with plenty of redundancy built in to the system.

Time here is critical because a route could be found but milliseconds later the balance sheets has changed and the funds are
no longer available to carry out the transaction and lets also remember we now have some centralization and transaction won't be in
this wonderful magic things called the public block-chain.

No wonder it taking them years to program this thing and its so hard to understand