solution: docs for ERC-20 tokens

docs/06-methods.adoc

@@ -52,10 +52,10 @@ Where:
 
 - `chain` target chain (see reference for ids)
 - `items` as a list of independent requests, which may be executed in different nodes in parallels or in different order, with:
- * `method` - a JSON RPC standard name, ex: `eth_getBlockByHash`
- * `payload` - list of parameters for the methods, encoded as JSON string, ex. `["0xe670ec64341771606e55d6b4ca35a1a6b75ee3d5145a99d05921026d1527331", true]`
+* `method` - a JSON RPC standard name, ex: `eth_getBlockByHash`
+* `payload` - list of parameters for the methods, encoded as JSON string, ex. `["0xe670ec64341771606e55d6b4ca35a1a6b75ee3d5145a99d05921026d1527331", true]`
 - `Selector` and `AvailabilityEnum` are described in reference, in short they allow to specify which nodes must be selected
-  to execute the reques (i.e. "execute only on an archive node")
+to execute the reques (i.e. "execute only on an archive node")
 
 .NativeCallReplyItem
 [source,proto]
@@ -71,7 +71,7 @@ message NativeCallReplyItem {
 
 Where:
 
-- `payload` is JSON response for a particular call, encoded into a string (when `succeed` is true)
+- `payload` is JSON response for a particular call (`result` field), encoded into a string (`succeed` is true)
 - or `error` if request failed (`succeed` is false)
 
 NOTE: Reply Items comes right after their execution on an upstream, therefore streaming response.
@@ -106,7 +106,8 @@ Where:
 
 === SubscribeBalance or GetBalance
 
-Subscribes to changes (`SubscribeBalance`) or get current (`GetBalance`) balance for a single address or a set of addresses.
+Subscribes to changes (`SubscribeBalance`) or get current (`GetBalance`) balance for a single address, or a set of addresses.
+By default, it supports only main protocol coin (i.e. `bitcoin`, `ether`), but can be configured to support ERC-20 on Ethereum (see link:reference-configuration.adoc[Reference Configuration])
 
 .Request
 [source,proto]

docs/reference-configuration.adoc

@@ -46,6 +46,18 @@ proxy:
     - id: kovan
       blockchain: kovan
 
+tokens:
+  - id: dai
+    blockchain: ethereum
+    name: DAI
+    type: ERC-20
+    address: 0x6B175474E89094C44Da98b954EedeAC495271d0F
+  - id: tether
+    blockchain: ethereum
+    name: Tether
+    type: ERC-20
+    address: 0xdac17f958d2ee523a2206206994597c13d831ec7
+
 cluster:
   defaults:
     - chains:
@@ -130,6 +142,11 @@ cluster:
 |
 | Setup HTTP proxy that emulates all standard JSON RPC requests. See <<proxy>> section
 
+| `tokens`
+|
+| Configure tokens for tracking balance. See <<tokens>> section
+
+
 | `cache`
 |
 | Caching configuration. See <<cache>> section.
@@ -242,6 +259,49 @@ a| Routing paths for Proxy. The proxy will handle requests as `https://${HOST}:$
 
 |===
 
+[#tokens]
+== Tokens config
+
+[source,yaml]
+----
+tokens:
+  - id: dai
+    blockchain: ethereum
+    name: DAI
+    type: ERC-20
+    address: 0x6B175474E89094C44Da98b954EedeAC495271d0F
+  - id: tether
+    blockchain: ethereum
+    name: Tether
+    type: ERC-20
+    address: 0xdac17f958d2ee523a2206206994597c13d831ec7
+----
+
+Tokens config enables tracking of a balance amount in the configured tokens.
+After making the configuration above you can request balance (`GetBalance`), or subscribe to balance changes (`SubscribeBalance`), using link:06-methods.adoc[enhanced protocol]
+
+.Token config
+[cols="2a,7"]
+|===
+| Option | Description
+
+| `id`
+| Internal id for reference (used in logging, etc)
+
+| `blockchain`
+| An ethereum-based blockchain where the contract is deployed
+
+| `name`
+| Name of the token, used for balance response as asset code (as converted to UPPERCASE)
+
+| `type`
+| Type of token. Only `ERC-20` is supported at this moment
+
+| `address`
+| Address of the deployed contract
+
+|===
+
 [#cache]
 == Cache config