diff --git a/README.md b/README.md index 964121e21..05e3512c6 100644 --- a/README.md +++ b/README.md @@ -1,17 +1,15 @@ -# Basecoin +# Quark -_DISCLAIMER: Basecoin is not associated with Coinbase.com, an excellent Bitcoin/Ethereum service._ +Quark is an [ABCI application](https://github.com/tendermint/abci) designed to +be used with the [Tendermint consensus engine](https://tendermint.com/) to form +a Proof-of-Stake cryptocurrency. It also provides a general purpose framework +for extending the feature-set of the cryptocurrency by implementing plugins. -Basecoin is an [ABCI application](https://github.com/tendermint/abci) designed to be used with the [Tendermint consensus engine](https://tendermint.com/) to form a Proof-of-Stake cryptocurrency. -It also provides a general purpose framework for extending the feature-set of the cryptocurrency -by implementing plugins. - -Basecoin serves as a reference implementation for how we build ABCI applications in Go, -and is the framework in which we implement the [Cosmos Hub](https://cosmos.network). -**It's easy to use, and doesn't require any forking** - just implement your plugin, import the basecoin libraries, -and away you go with a full-stack blockchain and command line tool for transacting. - -WARNING: Currently uses plain-text private keys for transactions and is otherwise not production ready. +Quark serves as a reference implementation for how we build ABCI applications +in Go, and is the framework in which we implement the [Cosmos +Hub](https://cosmos.network). **It's easy to use, and doesn't require any +forking** - just implement your plugin, import the quark libraries, and away +you go with a full-stack blockchain and command line tool for transacting. ## Prerequisites @@ -28,10 +26,10 @@ See the [install guide](/docs/guide/install.md) for more details. ## Guide -1. Getting started with the [Basecoin basics](/docs/guide/basecoin-basics.md) +1. Getting started with the [Quark basics](/docs/guide/basecoin-basics.md) 1. Learning to [use the plugin system](/docs/guide/basecoin-plugins.md) -1. More features of the [Basecoin tool](/docs/guide/basecoin-tool.md) -1. Learn how to use [InterBlockchain Communication (IBC)](/docs/guide/ibc.md) +1. More features of the [Quark tool](/docs/guide/basecoin-tool.md) +1. Learn how to use [Inter-Blockchain Communication (IBC)](/docs/guide/ibc.md) 1. See [more examples](github.com/tendermint/basecoin-examples) diff --git a/docs/quark/README.md b/docs/quark/README.md index bb53f7beb..ea2ce0bfe 100644 --- a/docs/quark/README.md +++ b/docs/quark/README.md @@ -1,32 +1,39 @@ # Quark -Quarks are the building blocks of atoms. And in a similar vein, this -package is a framework for building the cosmos. It gives you all the tools -you need to quickly build up powerful abci applications to run on tendermint, -while also providing maximum flexibility to customize aspects of your -application (do you require fees, how do you want to log messages, do you -enable IBC, do you even have a cryptocurrency?) +Quarks are the fundamental building blocks of atoms through which DNA, life, +and matter arise. Similarly this package is the core framework for constructing +the atom tokens which will power [The Cosmos Network](https://cosmos.network/). -However, when power and flexibility meet, the result is also some level of +The Quark framework affords you all the tools you need to rapidly develop +robust blockchains and blockchain applications which are interoperable with The +Cosmos Hub. Quark is an abstraction of [Tendermint](https://tendermint.com/) +which provides the core consensus engine for your blockchain. Beyond consensus, +Quark provides a blockchain development 'starter-pack' of common blockchain +modules while not enforcing their use thus giving maximum flexibility for +application customization. For example, do you require fees, how do you +want to log messages, do you enable IBC, do you even have a cryptocurrency? + +Disclaimer: when power and flexibility meet, the result is also some level of complexity and a learning curve. Here is an introduction to the core concepts -embedded in quarks, so you can apply them properly. +embedded in Quark. ## Inspiration -The basic concept came from years of web development. After decades of web -development, a number of patterns have arisen that enabled people to build -remote servers with APIs remarkably quickly and with high stability. -I think the ABCI app interface is similar to a web api (DeliverTx is like POST -and Query is like GET and SetOption is like the admin playing with the config -file). Here are some patterns that might be useful: +The basic concept came from years of web development. A number of patterns +have arisen in that realm of software which enable people to build remote +servers with APIs remarkably quickly and with high stability. The +[ABCI](https://github.com/tendermint/abci) application interface is similar to +a web API (DeliverTx is like POST and Query is like GET and `SetOption` is like +the admin playing with the config file). Here are some patterns that might be +useful: * MVC - separate data model (storage) from business logic (controllers) * Routers - easily direct each request to the appropriate controller * Middleware - a series of wrappers that provide global functionality (like authentication) to all controllers -* Modules (gems, package, ...) - people can write a self-contained package - with a given set of functionality, which can be imported and reused in - other apps +* Modules (gems, package, ...) - developers can write a self-contained package + with a given set of functionality, which can be imported and reused in other + apps Also, the idea of different tables/schemas in databases, so you can keep the different modules safely separated and avoid any accidental (or malicious) @@ -41,6 +48,6 @@ into various applications. * [Glossary of the terms](glossary.md) * [Standard modules](stdlib.md) * Guide to building a module -* Demo of cli tool +* Demo of CLI tool * IBC in detail -* Diagrams!!! +* Diagrams... Coming Soon! diff --git a/docs/quark/glossary.md b/docs/quark/glossary.md index 5a905d03b..16a0b8a09 100644 --- a/docs/quark/glossary.md +++ b/docs/quark/glossary.md @@ -1,31 +1,33 @@ # Glossary -This defines many of the terms that are used in the other documents. If there -is every a concept that seems unclear, check here. This is mainly to provide -a background and general understanding of the different words and concepts -that are used. Other documents will explain in more detail how to combine -these concepts to build a particular application. +This glossary defines many terms used throughout documentation of Quark. If +there is every a concept that seems unclear, check here. This is mainly to +provide a background and general understanding of the different words and +concepts that are used. Other documents will explain in more detail how to +combine these concepts to build a particular application. -## Transaction +## Transaction (tx) A transaction is a packet of binary data that contains all information to -validate and perform an action on the blockchain. The only other data that -it interacts with is the current state of the chain (kv store), and it must -have a deterministic action. The transaction is the main piece of one request. +validate and perform an action on the blockchain. The only other data that it +interacts with is the current state of the chain (key-value store), and +it must have a deterministic action. The tx is the main piece of one request. -We currently make heavy use of go-wire and go-data to provide automatic binary -and json encodings (and decodings) for objects, even when they embed many -interfaces inside. There is one public `TxMapper` in the basecoin root package, -and all modules can register their own transaction types there. This allows us -to deserialize the entire tx in one location (even with types defined in other -repos), to easily embed an arbitrary Tx inside another without specifying -the specific type, and provide an automatic json representation to provide to -users (or apps) to inspect the chain. +We currently make heavy use of [go-wire](https://github.com/tendermint/go-wire) +and [data](https://github.com/tendermint/go-wire/tree/master/data) to provide +binary and json encodings and decodings for `struct` or interface` objects. +Here, encoding and decoding operations are designed to operate with interfaces +nested any amount times (like an onion!). There is one public `TxMapper` +in the basecoin root package, and all modules can register their own transaction types there. This allows us to deserialize the entire tx in +one location (even with types defined in other repos), to easily embed +an arbitrary tx inside another without specifying the type, and provide +an automatic json representation to provide to users (or apps) to +inspect the chain. Note how we can wrap any other transaction, add a fee level, and not worry about the encoding in our module any more? -```Go +```golang type Fee struct { Fee coin.Coin `json:"fee"` Payer basecoin.Actor `json:"payer"` // the address who pays the fee @@ -33,54 +35,68 @@ type Fee struct { } ``` -## Context +## Context (ctx) -As the request passes through the system, it can pick up information, that must -be carried along with it. Like the authorized it has received from another -middleware, or the block height it runs at. This is all deterministic -information from the context in which the request runs (based on the tx and -the block it was included in) and can be used to validate the tx. +As a request passes through the system, it may pick up information such as the +authorization it has received from another middleware, or the block height the +request runs at. In order to carry this information between modules it is +saved to the context. further, it all information must be deterministic from +the context in which the request runs (based on the tx and the block it was +included in) and can be used to validate the tx. ## Data Store -To be able to provide proofs to tendermint, we keep all data in one key-value -store, indexed with a merkle tree. This allows us to easily provide a root -hash and proofs for queries without requiring complex logic inside each -module. Standarizing this also allows powerful light-client tooling as it knows -how to verify all data in the store. +To be able to provide proofs to Tendermint, we keep all data in one key-value +(kv) store which is indexed with a merkle tree. This allows for the easy +generation of a root hash and proofs for queries without requiring complex +logic inside each module. Standardization of this process also allows powerful +light-client tooling as any store data may be verified on the fly. -The downside is there is one quite simple interface that the application has -to `Get` and `Set` data. There is not even a range query. Although there are -some data structures like queues and range queries that are also in the `state` -package to provide higher-level functionality in a standard format. +The largest limitation of the current implemenation of the kv-store is that +interface that the application must use can only `Get` and `Set` single data +points. This said, there are some data structures like queues and range +queries that are available in `state` package. These provide higher-level +functionality in a standard format, but have not yet been integrated into the +kv-store interface. ## Isolation One of the main arguments for blockchain is security. So while we encourage -the use of third-party modules, we must be vigilant against security holes. -If you use the `stack` package, it will provide two different types of -sandboxing for you. +the use of third-party modules, all developers must be vigilant against +security holes. If you use the +[stack](https://github.com/tendermint/basecoin/tree/unstable/stack) +package, it will provide two different types of compartmentalization security. -The first step, is that when `DeliverTx` is called on a module, it is never -given the entire data store, but rather only its own prefixed section. This -is achieved by prefixing all keys transparently with ` + 0x0`, -using the null byte as a separator. Since module name must be a string, no -clever naming scheme can lead to a collision. Inside the module, we can write -anywhere we want, without worry that we have to touch some data that is not ours. +The first is to limit the working kv-store space of each module. When +`DeliverTx` is called for a module, it is never given the entire data store, +but rather only its own prefixed subset of the store. This is achieved by +prefixing all keys transparently with ` + 0x0`, using the null +byte as a separator. Since the module name must be a string, no malicious +naming scheme can ever lead to a collision. Inside a module, we can +write using any key value we desire without the possibility that we +have modified data belonging to separate module. -The second step involves the permissions in the context. The context can say -that this tx was signed by eg. Rigel. But if any module can add that permission, -it would be too easy to forge accounts. Thus, each permission is associated -with the module that granted it (in this case `auth`), and if a module tries -to add a permission for another module, it will panic. There is also -protection if a module creates a brand new fake context to trick the downstream -modules. +The second is to add permissions to the transaction context. The tx context +can specify that the tx has been signed by one or multiple specific +[actors](https://github.com/tendermint/basecoin/blob/unstable/context.go#L18). +A tx will only be executed if the permission requirements have been fulfilled. +For example the sender of funds must have signed, or 2 out of 3 +multi-signature actors must have signed a joint account. To prevent the +forgery of account signatures from unintended modules each permission +is associated with the module that granted it (in this case +[auth](https://github.com/tendermint/basecoin/tree/unstable/modules/auth)), +and if a module tries to add a permission for another module, it will +panic. There is also protection if a module creates a brand new fake +context to trick the downstream modules. Each context enforces +the rules on how to make child contexts, and the stack middleware builder +enforces that the context passed from one level to the next is a valid +child of the original one. -This means that modules can confidently write to their local section of the -database and trust the permissions associated with the context, without concern -of interferance from other modules. (Okay, if you see a bunch of C-code in -the module traversing through all the memory space of the application, then -get worried....) +These security measures ensure that modules can confidently write to their +local section of the database and trust the permissions associated with the +context, without concern of interference from other modules. (Okay, +if you see a bunch of C-code in the module traversing through all the +memory space of the application, then get worried....) ## Handler @@ -89,19 +105,19 @@ into an internal format that is more convenient, but unable to travel over the wire. The basic interface for any code that modifies state is the `Handler` interface, which provides four methods: -```Go +```golang Name() string CheckTx(ctx Context, store state.KVStore, tx Tx) (Result, error) DeliverTx(ctx Context, store state.KVStore, tx Tx) (Result, error) SetOption(l log.Logger, store state.KVStore, module, key, value string) (string, error) ``` -Note the `Context`, `Store`, and `Tx` as principal carriers of information. And -that Result is always success, and we have a second error return for errors -(which is much more standard go that `res.IsErr()`) +Note the `Context`, `KVStore`, and `Tx` as principal carriers of information. +And that Result is always success, and we have a second error return +for errors (which is much more standard golang that `res.IsErr()`) The `Handler` interface is designed to be the basis for all modules that -execute transaction, and this can provide a large degree of code +execute transactions, and this can provide a large degree of code interoperability, much like `http.Handler` does in golang web development. ## Middleware @@ -110,16 +126,16 @@ Middleware is a series of processing steps that any request must travel through before (and after) executing the registered `Handler`. Some examples are a logger (that records the time before executing the tx, then outputs info - including duration - after the execution), of a signature checker (which -unwraps the tx by one layer, verifies signatutes, and adds the permissions to +unwraps the tx by one layer, verifies signatures, and adds the permissions to the Context before passing the request along). -In keeping with the standardazation of `http.Handler` and inspired by the +In keeping with the standardization of `http.Handler` and inspired by the super minimal [negroni](https://github.com/urfave/negroni/blob/master/README.md) package, we just provide one more `Middleware` interface, which has an extra `next` parameter, and a `Stack` that can wire all the levels together (which also gives us a place to perform isolation of each step). -```Go +```golang Name() string CheckTx(ctx Context, store state.KVStore, tx Tx, next Checker) (Result, error) DeliverTx(ctx Context, store state.KVStore, tx Tx, next Deliver) (Result, error) @@ -128,19 +144,20 @@ also gives us a place to perform isolation of each step). ## Modules -A module is a set of functionality that is more or less self-sufficient. It -usually contains the following pieces: +A module is a set of functionality which should be typically designed as +self-sufficient. Common elements of a module are: * transaction types (either end transactions, or transaction wrappers) * custom error codes -* data models (to persist in the kv store) +* data models (to persist in the kv-store) * handler (to handle any end transactions) * middleware (to handler any wrapper transactions) To enable a module, you must add the appropriate middleware (if any) to the -stack in main.go, as well as adding the handler (if any) to the dispatcher. -One the stack is compiled into a `Handler`, then all tx are handled by the -proper module. +stack in `main.go` for the client application (Quark default: +`basecli/main.go`), as well as adding the handler (if any) to the dispatcher +(Quark default: `app/app.go). Once the stack is compiled into a `Handler`, +then each tx is handled by the appropriate module. ## Dispatcher @@ -163,47 +180,49 @@ This all seems a bit of magic, but really just making use of the other magic thing you need to remember is to use the following pattern, then all the tx will be properly routed: -```Go +```golang const ( NameCoin = "coin" TypeSend = NameCoin + "/send" ) ``` -## IPC (Inter-Plugin Communication) +## Inter-Plugin Communication (IPC) But wait, there's more... since we have isolated all the modules from each other, we need to allow some way for them to interact in a controlled fashion. -Some examples are the `fee` middleware, which wants to deduct coins from -the calling account (in the `coin` module), or a vote that requires a payment. +One example is the `fee` middleware, which wants to deduct coins from the +calling account and can accomplished most easilty with the `coin` module. -If we want to make a call from the middleware, this is relatively simple. -The middleware already has a handle to the `next` Handler, which will -execute the rest of the stack. It can simple create a new SendTx and pass -it down the stack. If it returns success, then do the rest of the processing -(and send the original tx down the stack), otherwise abort. +If we want to make a call from the middleware, this is relatively simple. The +middleware already has a handle to the `next` Handler, which will execute the +rest of the stack. It can simple create a new SendTx and pass it down the +stack. If it returns success, then do the rest of the processing (and send the +original tx down the stack), otherwise abort. -However, if one `Handler` inside the `Dispatcher` wants to do this, it -becomes more complex. The solution is that the `Dispatcher` accepts not -a `Handler`, but a `Dispatchable`, which looks like a middleware, except -that the `next` argument is a callback to the dispatcher to execute a -sub-transaction. If a module doesn't want to use this functionality, -it can just implement `Handler` and call `stack.WrapHandler(h)` to convert -it to a `Dispatchable` that never uses the callback. +However, if one `Handler` inside the `Dispatcher` wants to do this, it becomes +more complex. The solution is that the `Dispatcher` accepts not a `Handler`, +but a `Dispatchable`, which looks like a middleware, except that the `next` +argument is a callback to the dispatcher to execute a sub-transaction. If a +module doesn't want to use this functionality, it can just implement `Handler` +and call `stack.WrapHandler(h)` to convert it to a `Dispatchable` that never +uses the callback. One example of this is the counter app, which can optionally accept a payment. If the tx contains a payment, it must create a SendTx and pass this to the dispatcher to deduct the amount from the proper account. Take a look at -[counter plugin](https://github.com/tendermint/basecoin/blob/unstable/docs/guide/counter/plugins/counter/counter.go) for a better idea. +[counter +plugin](https://github.com/tendermint/basecoin/blob/unstable/docs/guide/counter/plugins/counter/counter.go) +for a better idea. ## Permissions -This system requires a more complex permissioning system to allow the modules -to have limited access to each other. Also to allow more types of permissions -than simple public key signatures. So, rather than just use an address to -identify who is performing an action, we can use a more complex structure: +IPC requires a more complex permissioning system to allow the modules to have +limited access to each other. Also to allow more types of permissions than +simple public key signatures. So, rather than just use an address to identify +who is performing an action, we can use a more complex structure: -```Go +```golang type Actor struct { ChainID string `json:"chain"` // this is empty unless it comes from a different chain App string `json:"app"` // the app that the actor belongs to @@ -211,32 +230,70 @@ type Actor struct { } ``` +Here, the `Actor` abstracts any address that can authorize actions, hold funds, +or initiate any sort of transaction. It doesn't just have to be a pubkey on +this chain, it could stem from another app (such as multi-sig account), or even +another chain (via IBC) + `ChainID` is to be used for IBC, which is discussed below, but right now focus -on `App` and `Address`. For a signature, the App is `auth`, and any modules can -check to see if a specific public key address signed like this -`ctx.HasPermission(auth.SigPerm(addr))`. However, we can also authorize a -tx with `roles`, which handles multi-sig accounts, it checks if there were -enough signatures by checking as above, then it can add the role permission like -`ctx = ctx.WithPermissions(NewPerm(assume.Role))` +on `App` and `Address`. For a signature, the App is `auth`, and any modules +can check to see if a specific public key address signed like this +`ctx.HasPermission(auth.SigPerm(addr))`. However, we can also authorize a tx +with `roles`, which handles multi-sig accounts, it checks if there were enough +signatures by checking as above, then it can add the role permission like `ctx += ctx.WithPermissions(NewPerm(assume.Role))` In addition to permissioning, the Actors are addresses just like public key -addresses. So one can create a mulit-sig role, then send coin there, which -can only be moved upon meeting the authorization requirements from that module. -`coin` doesn't even know the existence of `roles` and one could build any -other sort of module to provide permissions (like bind the outcome of an -election to move coins or to modify the accounts on a role). +addresses. So one can create a mulit-sig role, then send coin there, which can +only be moved upon meeting the authorization requirements from that module. +`coin` doesn't even know the existence of `roles` and one could build any other +sort of module to provide permissions (like bind the outcome of an election to +move coins or to modify the accounts on a role). One idea (not implemented) is to provide scopes on the permissions. Right now, if I sign a tx to one module, it can pass it on to any other module over IPC with the same permissions. It could move coins, vote in an election, or anything else. Ideally, when signing, one could also specify the scope(s) that -this signature authorizes. The [oauth protocol](https://api.slack.com/docs/oauth-scopes) -also has to deal with a similar problem, and maybe could provide some inspiration. +this signature authorizes. The [oauth +protocol](https://api.slack.com/docs/oauth-scopes) also has to deal with a +similar problem, and maybe could provide some inspiration. + ## Replay Protection -Is implemented as middleware. Rigel can add more info here. Or look -at [the github issue](https://github.com/tendermint/basecoin/issues/160) +In order to prevent [replay +attacks](https://en.wikipedia.org/wiki/Replay_attack) a multi account nonce system +has been constructed as a module, which can be found in +`modules/nonce`. By adding the nonce module to the stack, each +transaction is verified for authenticity against replay attacks. This is +achieved by requiring that a new signed copy of the sequence number which must +be exactly 1 greater than the sequence number of the previous transaction. A +distinct sequence number is assigned per chain-id, application, and group of +signers. Each sequence number is tracked as a nonce-store entry where the key +is the marshaled list of actors after having been sorted by chain, app, and +address. + +```golang +// Tx - Nonce transaction structure, contains list of signers and current sequence number +type Tx struct { + Sequence uint32 `json:"sequence"` + Signers []basecoin.Actor `json:"signers"` + Tx basecoin.Tx `json:"tx"` +} +``` + +By distinguishing sequence numbers across groups of Signers, multi-signature +Actors need not lock up use of their Address while waiting for all the members +of a multi-sig transaction to occur. Instead only the multi-sig account will +be locked, while other accounts belonging to that signer can be used and signed +with other sequence numbers. + +By abstracting out the nonce module in the stack, entire series of transactions +can occur without needing to verify the nonce for each member of the series. An +common example is a stack which will send coins and charge a fee. Within Quark +this can be achieved using separate modules in a stack, one to send the coins +and the other to charge the fee, however both modules do not need to check the +nonce. This can occur as a separate module earlier in the stack. ## IBC (Inter-Blockchain Communication) diff --git a/docs/quark/stdlib.md b/docs/quark/stdlib.md index aac20a64c..97965c941 100644 --- a/docs/quark/stdlib.md +++ b/docs/quark/stdlib.md @@ -1,96 +1,106 @@ # Standard Library -The quarks framework comes with a number of standard modules that provide a lot -of common functionality that is useful to a wide variety of applications, -and also provide good examples to use when developing your own modules. Before -starting to write code, see if the functionality is already here. +The Quark framework comes bundled with a number of standard modules that +provide common functionality useful across a wide variety of applications. +Example usage of the modules is also provided. It is recommended to investigate +if desired functionality is already provided before developing new modules. ## Basic Middleware ### Logging -`modules.base.Logger` is a middleware that records basic info on CheckTx, -DeliverTx, and SetOption, along with timing in microseconds. It can be installed -standard at the top of all middleware stacks, or replace it with your own -Middleware if you want to record more custom information with each request. +`modules.base.Logger` is a middleware that records basic info on `CheckTx`, +`DeliverTx`, and `SetOption`, along with timing in microseconds. It can be +installed standard at the top of all middleware stacks, or replaced with your +own middleware if you want to record custom information with each request. ### Recovery -To avoid accidental panics (eg. bad go-wire decoding) killing the abci app, +To avoid accidental panics (e.g. bad go-wire decoding) killing the ABCI app, wrap the stack with `stack.Recovery`, which catches all panics and returns them as errors, so they can be handled normally. ### Signatures -The first layer of the tx contains the signatures to authorize it. This is then -verfied by `modules.auth.Signatures`. All tx may have one or multiple signatures -which are then processed and verified by this middleware and then passed down -the stack. +The first layer of the tx contains the signatures to authorize it. This is +then verified by `modules.auth.Signatures`. All tx may have one or multiple +signatures which are then processed and verified by this middleware and then +passed down the stack. ### Chain The next layer of a tx (in the standard stack) binds the tx to a specific chain with an optional expiration height. This keeps the tx from being replayed on -a fork or other such chain, as well as a partially signed multisig being delayed +a fork or other such chain, as well as a partially signed multi-sig being delayed months before being committed to the chain. This functionality is provided in `modules.base.Chain` ### Nonce -To avoid replay protection within one chain, we want a nonce associated -with each account. Rather than force everything to use coins as a payment,or force each module to implement its own replay protection, each tx is wraped with a nonce and -the account it belongs to. This must be one higher than the last request or -the request is rejected. This is implemented in `modules.nonce.ReplayCheck` +To avoid replay attacks, a nonce can be associated with each actor. A separate +nonce is used for each distinct group signers required for a transaction as +well as for each separate application and chain-id. This creates replay +protection cross-IBC and cross-plugins and also allows signing parties to not +be bound to waiting for a particular transaction to be completed before being +able to sign a separate transaction. -You can also take a look at the [design discussion](https://github.com/tendermint/basecoin/issues/160) + Rather than force each module to implement its own replay protection, a tx +stack may contain a nonce wrap and the account it belongs to. The nonce must +contain a signed sequence number which is incremented one higher than the last +request or the request is rejected. This is implemented in +`modules.nonce.ReplayCheck` + +If you're interested checkout this [design +discussion](https://github.com/tendermint/basecoin/issues/160). ### Fees -An optional feature, but useful on many chains, is charging a fee for every -transaction. A simple implementation of this is provided in -`modules.fee.SimpleFeeMiddleware`. A fee currency and minimum amount are -defined in the constructor (eg. in code). If the minimum amount is 0, then -the fee is optional. If it is above 0, then every tx with insufficient fee is -rejected. This fee is deducted from the payers account before executing any -other transaction. +An optional feature, but useful on many chains, is charging transaction fees. A +simple implementation of this is provided in `modules.fee.SimpleFeeMiddleware`. +A fee currency and minimum amount are defined in the constructor (eg. in code). +If the minimum amount is 0, then the fee is optional. If it is above 0, then +every tx with insufficient fee is rejected. This fee is deducted from the +payers account before executing any other transaction. -This module depends on the `coin` module. +This module is dependent on the `coin` module. ## Other Apps ### Coin -What would a crypto-currency be without tokens? The sendtx logic from basecoin -was extracted into one module, which is now optional, meaning most of the other -functionality would also work in a system with no built-in tokens, such as -a private network that provides another access control mechanism. +What would a crypto-currency be without tokens? The `SendTx` logic from earlier +implementations of basecoin was extracted into one module, which is now +optional, meaning most of the other functionality will also work in a system +with no built-in tokens, such as a private network that provides other access +control mechanisms. `modules.coin.Handler` defines a Handler that maintains a number of accounts -along with a set of various tokens, supporting multiple denominations. The -main access is `SendTx`, which can support any type of actor (other apps as -well as public key addresses), and is a building block for any other app that +along with a set of various tokens, supporting multiple token denominations. +The main access is `SendTx`, which can support any type of actor (other apps as +well as public key addresses) and is a building block for any other app that requires some payment solution, like fees or trader. ### Roles Roles encapsulates what are typically called N-of-M multi-signatures accounts in the crypto world. However, I view this as a type of role or group, which can -be the basis for building a permision system. For example, a set of people could -be called registrars, which can authorize a new IBC chain, and need eg. 2 out -of 7 signatures to approve it. +be the basis for building a permission system. For example, a set of people +could be called registrars, which can authorize a new IBC chain, and need eg. 2 +out of 7 signatures to approve it. Currently, one can create a role with `modules.roles.Handler`, and assume one of those roles by wrapping another transaction with `AssumeRoleTx`, which is processed by `modules.roles.Middleware`. Updating the set of actors in a role is planned in the near future. -### IBC +### Inter-Blockchain Communication (IBC) -IBC, or inter-blockchain communication, is the cornerstone of cosmos, and built -into the quark framework as a basic primative. To properly understand these -concepts requires a much longer explanation, but in short, the chain works -as a light-client to another chain and maintains input and output queue to -send packets with that chain. +IBC, is the cornerstone of The Cosmos Network, and is built into the quark +framework as a basic primitive. To fully grasp these concepts requires +a much longer explanation, but in short, the chain works as a light-client to +another chain and maintains input and output queue to send packets with that +chain. This mechanism allows blockchains to prove the state of their respective +blockchains to each other ultimately invoke inter-blockchain transactions. Most functionality is implemented in `modules.ibc.Handler`. Registering a chain is a seed of trust that requires verification of the proper seed (or genesis @@ -100,7 +110,7 @@ as the new header can be completely verified by the existing knowledge of the chain. Also, modules can initiate an outgoing IBC message to another chain by calling `CreatePacketTx` over IPC (inter-plugin communication) with a tx that belongs to their module. (This must be explicitly authorized by the -same module, so only the eg. coin module can authorize a sendtx to another +same module, so only the eg. coin module can authorize a `SendTx` to another chain). `PostPacketTx` can post a tx that was created on another chain along with the @@ -127,6 +137,7 @@ governance. ### Trader -Escrow, OTC option, Order book. Based on [basecoin-examples](https://github.com/tendermint/basecoin-examples/tree/develop/trader). This may be more appropriate -for an external repo. +Escrow, OTC option, Order book. Based on +[basecoin-examples](https://github.com/tendermint/basecoin-examples/tree/develop/trader). +This may be more appropriate for an external repo.