Add documentation (#12)

README.md

@@ -1,29 +1,263 @@
-# ISO20022 Client
+<div style="text-align: center">
+    <h1>ISO20022 Client</h1>
+</div>
 
-## Testing
-For testing, we need to open three command lines:
+<div style="text-align: center">
+    <img src="static/diagram.png" height="500px" width="500px" alt="ISO20022 Network Diagram"/>
+</div>
+
+## Definitions
+
+* **ISO20022**: As defined in [ISO20022 website](https://www.iso20022.org/):
+
+> ISO20022 is a single standardization approach (methodology, process, repository)
+> to be used by all financial standards initiatives.
+
+* **ISO20022 messaging system**: A decentralized messenger connecting financial institutions,
+  so they can pass their ISO20022 messages securely between each other,
+  like [SWIFT](https://swift.com) in traditional banks.
+  This system consists of a smart token deployed in a blockchain and a client application
+  distributed between financial institutions to connect to the smart contract.
+
+* **ISO20022 Client**: The application running on financial institutions'
+  infrastructure that abstracts away all the complexities related to blockchain
+  and acts as an HTTP server,
+  so other applications in the institution can send and receive ISO20022 messages to or from it.
+
+* **ISO20022 Message**: An XML file generated using financial applications (like accounting apps) using the ISO20022
+  standard describing a financial operation like transferring credits.
+
+## How It Works
+
+### The Flow
+
+The process of sending an ISO20022 message consists of 5 steps:
+
+1. Reading and parsing the XML file of the message and extracting the Financial Institution Identity information of the
+   recipient from each message
+2. Finding the wallet address and public key of the recipient from the address book
+3. Compressing the XML file and encrypting it with a symmetric key generated from the public key of the receiver and the
+   private key of the sender using diffie-hellman key exchange method
+4. Minting a NFT from the encrypted data
+5. Sending the NFT information to the smart contract, so it can store it with sender and recipient address
+
+The process of receiving an ISO20022 message consists of 7 steps:
+
+1. Querying new messages periodically
+2. Querying the NFT information of a received message
+3. Decrypting the NFT data using the symmetric key generated from the public key of the sender and the private key of
+   the recipient using diffie-hellman key exchange method and decompressing it
+4. Parsing the XML file of the message and extracting the Financial Institution Identity information of the sender from
+   the message
+5. Finding the wallet address of the sender from the address book
+6. Verifying if the sender of the message to the smart contract is the same with the sender in ISO20022 message
+7. Writing the XML message to a file
+
+### Example
+
+<div style="text-align: center">
+    <img src="static/example.png" width="500px" alt="PACS.008 Message Example"/>
+</div>
+
+As a simple example, let's say one person (Debtor) has an account in one financial institution (Debtor Agent)
+wants to transfer some credits to another person (Creditor) that has an account in another financial institution
+(Creditor Agent).
+
+The Debtor will send a `PAIN.001` (CustomerCreditTransferInitiation under Payment Initiation)
+message to the Debtor Agent which is outside of scope of this project.
+Then the Debtor Agent should transfer the credits to Creditor Agent, so the Creditor can receive the credit.
+
+Both financial institutions are connected to the ISO20022 messaging system using the ISO20022 client application.
+In traditional banking,
+the `PACS.008` message should be sent to SWIFT application to be delivered to the other financial institution.
+However, using this system,
+it should be sent to the HTTP server that ISO20022 client is running either directly to the HTTP server,
+or using the command line interface.
+It then extracts the actual receiver of the message,
+compresses and encrypts the message and delivers it to the smart contract.
+The Creditor Agent is polling the smart contract periodically,
+and it will receive the message that the Debtor Agent sent.
+It will receive,
+decrypt and decompress it and then the Creditor Agent can process the request and send a report to the Creditor using
+`CAMT.053` (BankToCustomerStatement under Cash Management) which is also outside of scope of this project.
+
+## Quick Start
+
+If you want to get started quickly and learn how to interact with the application
+first, you need to have the binary, initialize it, add your wallet key and register your institution.
+Then you can start the application and interact with it.
+
+### Download
+
+You can download the latest build from [Releases](https://github.com/CoreumFoundation/iso20022-client/releases) page
+of the repo according to your operating system (OS) and CPU architecture.
+
+Or you can clone the project and make it using:
+
+```bash
+make build
+```
+
+It's better to either copy the binary to one the paths listed in your `PATH` environment variable
+or add the binary directory to the `PATH` environment variable.
+
+To see the directories listed in your `PATH` environment variable, you can run:
+
+```bash
+echo $PATH
+```
+
+### Initialize
+
+When you want to work with the binary for the first time, you need to initialize it,
+so it can generate the right configuration for the application.
+
+Usually it's as easy as running:
+
+```bash
+iso20022-client init
+```
+
+But you have the option to configure it otherwise.
+For example, if you want to connect to testnet instead of mainnet, you can run:
+
+```bash
+iso20022-client init --chain-id=coreum-testnet-1 --coreum-contract-address=testcore19a3m5sqm4s4mjfkpj3r7mg2q0gamjeh24zqlqqg6ezncv6l95q9qahxn93 --coreum-grpc-url=https://full-node.testnet-1.coreum.dev:9090
+```
+
+### Add Key
+
+To be able to join the blockchain network, you need to have an account in Coreum blockchain.
+To have that, you need to use a [wallet](https://docs.coreum.dev/docs/tools/wallets)
+that is connected to Coreum mainnet and has enough funds to deliver messages.
+
+Sending each message to the network costs some small tokens, the fund is necessary for this purpose.
+
+Once you've created that, you can use the same mnemonics of the account in the ISO20022 Client,
+so it can use the same account:
 
-1. To run the sending party:
 ```bash
-./bin/iso20022-client start --server-addr=':2843' --key-name=iso20022-client --keyring-backend=test --cache-path=/tmp/iso20022-client-1
+iso20022-client keys add iso20022-client --recover
 ```
 
-2. To run the receiving party:
+Alternatively, you can generate the account in the ISO20022 Client:
+
 ```bash
-./bin/iso20022-client start --server-addr=':2844' --key-name=iso20022-client-2 --keyring-backend=test --cache-path=/tmp/iso20022-client-2
+iso20022-client keys add iso20022-client
+```
+
+And import the mnemonics to your wallet and fund your account.
+
+### Register Your Institution
+
+Each financial institution should be registered before being able to send or receive messages to the network.
+
+To do so, you need to have the ISO20022 Financial Institution Identity information of your institute,
+the wallet address and your public key.
+
+After adding your key to the application in the previous step, it will show you an output like this:
+
+```yaml
+-   address: core1tagmslrz9xqfyjdddt6nu3q97us3ejck6475n8
+    name: iso20022-client
+    pubkey: '{"@type":"/cosmos.crypto.secp256k1.PubKey","key":"AqV7ob5PTCKOaiOp6iD6tQvjGorS6xLJiGQaVRBvQzM+"}'
+    type: local
+```
+
+* The address written after the `address:` in the output is your wallet address.
+* The `key` part of the `pubkey` is your public key.
+* The ISO20022 Financial Institution Identity information is how you are identified in ISO20022 messages,
+  which usually is using a Business Identification Code (BIC).
+
+Now you need
+to create a pull request on [Address Book](https://github.com/CoreumFoundation/iso20022-addressbook)
+and add your information to it and wait for someone to validate your change and merge it.
+
+For the example above, you need an entry like this to `addresses`:
+
+```json
+{
+    "bech32_encoded_address": "core1tagmslrz9xqfyjdddt6nu3q97us3ejck6475n8",
+    "public_key": "AqV7ob5PTCKOaiOp6iD6tQvjGorS6xLJiGQaVRBvQzM+",
+    "party": {
+        "identification": {
+            "bic": "DDDDBEBB"
+        }
+    }
+}
 ```
 
-3. To send the message:
+_TODO: Replace with Google Form when we have it._
+
+Once your PR is merged, you can continue and start the application and interact with it.
+
+_Note: You are not obligated to use our Address Book.
+You can use our binary
+to send message between nodes in a community you want which uses another address book
+and change the address in the config file._
+
+_TODO: Instruction for validation using company's domain._
+
+### Start The Application
+
+To start the application, you need to run:
+
 ```bash
-./bin/iso20022-client message send /path/to/pacs008-request.xml --server-addr=':2843'
+iso20022-client start
 ```
 
-And then receive it:
+It will start the HTTP server on port `2843` that receives ISO20022 messages in XML format
+and delivers them to the smart contract deployed on blockchain.
+
+If you open the same port of your local machine in your browser,
+you can see the Swagger documentation of this HTTP server:
+
+[http://127.0.0.1:2843/](http://127.0.0.1:2843/)
+
+Usually the simple `start` command is enough to run the HTTP server,
+but if you need to run it on another port, or use another key name, you can do so like this:
+
 ```bash
-./bin/iso20022-client message receive /path/to/pacs008-response.xml --server-addr=':2844'
+iso20022-client start --server-addr=':2844' --key-name=iso20022-client-2
 ```
 
+The HTTP server should be running all the time, so you can interact with it.
+
+### Send & Receive
+
+Sending and receiving messages is done using HTTP requests like described in the Swagger API documentation,
+but as an alternative, there are `send` and `receive` command line sub commands available in the binary.
+
+Sending an ISO20022 message which is actually an XML file is done by:
+
+```bash
+iso20022-client message send /path/to/read/request.xml
+```
+
+Alternatively, if you have run your HTTP server using another port, you can do:
+
+```bash
+iso20022-client message send /path/to/read/request.xml --server-addr=':2843'
+```
+
+For receiving messages, you need to periodically run the `receive` sub command (or poll the HTTP endpoint):
+
+```bash
+iso20022-client message receive /path/to/write/response.xml
+```
+
+## Limitations
+
+For the first PoC version, the only supported Business Area (BA) is Payments Clearing and
+Settlement (PACS).
+
+## What's Next
+
+After the first PoC, we will implement an RTGS system that does the settlement between financial institutions using
+digital tokens instead of fiat money.
+
 ## TODO
 
 - [ ] Add new messages from [ISO20022 message definitions](https://www.iso20022.org/iso-20022-message-definitions).
-- [ ] Add old messages from [ISO20022 message archive](https://www.iso20022.org/catalogue-messages/iso-20022-messages-archive).
+- [ ] Add old messages
+  from [ISO20022 message archive](https://www.iso20022.org/catalogue-messages/iso-20022-messages-archive).