### Abstract



![image.png](https://images.hive.blog/DQmeKZYGw9p8xueqtRbhw2X2uPY7ro9jJX3hPbzVVr9Bj23/image.png)

----

As part of the Hive - Peerplays Sidechain implementation, we are now attempting to connect the sidechain listener to the Hive Public API endpoints. Previously we have been using fullfledged Hive TESTNET and Peerplays TESNET and the cross chain transfer from Hive TESTNET to Peerplays TESTNET was possible in around ~10 seconds. We have been expecting the same implementation to complete cross chain transfer of HIVE/HBD in less than 30 seconds. We have been streaming the Hive blockchain and looking for transactions in `account_history_api.get_transaction` every second. But with the Hive mainnet, the API nodes adds latency which results the cross chain swaps to slow down to around 80-100 seconds. 

Next steps are to attempt to listen for only the LIB (ie the irreversible blocks) every 3 seconds instead of looking for transactions every second. Further optimizations in the required RPC calls can also provide better performance.  (Results will be announced).

In general it looks like solutions like HAF, ie moving the account history to proven and battle tested general purposed databases like PostgreSQL can provide much needed response times for financial applications.


### Current Challenges



 - `block_api.get_block` call is slow (details to follow)

- `account_history_api.get_transaction` Often fails on the Hive Mainnet's public full nodes

- some of the nodes seems to have compiled with `SKIP_BY_TX_ID=ON` & thus fails to return full data.



### Hive - Peerplays Sidechain listener logic



The following logic is used for listening the transactions in the Hive blockchain in real time. Upon meeting the criteria, deposit or withdraw of HIVE/HBD assets are invoked and under goes consensus process by the Sidechain Operator Nodes. Note that the implementation is in C++ and for now we are using a slower curl based implementation that supports HTTPS as part of the Peerplays chain's Hive listener. Initially we have been using HTTP and thus that also might be adding a small amount of delay.

- call, once, `database_api.get_version` to get `chain_id `
- call, once, `condenser_api.get_config` to verify are we running on testnet or mainnet 
- loop start
- call, each second, `database_api.get_dynamic_global_properties` to monitor for new blocks (ie, we are looking into `head_block_number field`) 
- if** new block is available (ie, head_block_number is increased), we call `block_api.get_block`, to get the block 
- we are iterrating through block transactions, in order to find any transaction with `transfer_operation` of interest
- we call `account_history_api.get_transaction`, for each transaction id in a block (these calls fail on mainnet)

```
840114ms th_a       rpc_client.cpp:171            send_post_request    ] ### Request URL:    https://api.hive.blog:443      840114ms th_a       rpc_client.cpp:172            send_post_request    ] ### Request:        { "jsonrpc": "2.0", "id": 5, "method": "account_history_api.get_transaction", "params": { "id": "bbea1d35998433e534e8b57f0945c32d1bbd3bd0", "include_reversible": "true" } }      840114ms th_a       rpc_client.cpp:174            send_post_request    ] ### Response:       {"jsonrpc":"2.0","error":{"code":-32003,"message":"Assert Exception:false: Unknown Transaction bbea1d35998433e534e8b57f0945c32d1bbd3bd0","data":{"code":10,"name":"assert_exception","message":"Assert Exception","stack":[{"context":{"level":"error","file":"account_history_api.cpp","line":250,"method":"get_transaction","hostname":"","timestamp":"2021-10-12T13:14:00"},"format":"false: Unknown Transaction ${t}","data":{"t":"bbea1d35998433e534e8b57f0945c32d1bbd3bd0"}}]}},"id":5}
```

- we parse the transaction, looking for transfer_operation with son-account as a receiver 
- if we find it, we create appropriate deposit object 
- SONs are calling account_history_api_get_transaction, again during deposit object verification, to confirm that the deposit transaction exists, and that data in the transaction matches data in the deposit object (sender, receiver, asset symbol, amount) 
- for withdrawals we use network_broadcast_api.broadcast_transaction to bradcast payout transaction, and we monitor if the transaction reached irreeversible block, by calling database_api.get_dynamic_global_properties and looking into field last_irreversible_block_num. If transaction reached irreversible block, withdrawal is confirmed.



### Issue logs



- **account_history_api.get_transaction**

```
840114ms th_a       rpc_client.cpp:171            send_post_request    ] ### Request URL:    https://api.hive.blog:443      840114ms th_a       rpc_client.cpp:172            send_post_request    ] ### Request:        { "jsonrpc": "2.0", "id": 5, "method": "account_history_api.get_transaction", "params": { "id": "bbea1d35998433e534e8b57f0945c32d1bbd3bd0", "include_reversible": "true" } }      840114ms th_a       rpc_client.cpp:174            send_post_request    ] ### Response:       {"jsonrpc":"2.0","error":{"code":-32003,"message":"Assert Exception:false: Unknown Transaction bbea1d35998433e534e8b57f0945c32d1bbd3bd0","data":{"code":10,"name":"assert_exception","message":"Assert Exception","stack":[{"context":{"level":"error","file":"account_history_api.cpp","line":250,"method":"get_transaction","hostname":"","timestamp":"2021-10-12T13:14:00"},"format":"false: Unknown Transaction ${t}","data":{"t":"bbea1d35998433e534e8b57f0945c32d1bbd3bd0"}}]}},"id":5}
```

- **Nodes with SKIP_BY_TX_ID=ON**

  `curl -s --data '{"jsonrpc":"2.0","id":5,"method":"account_history_api.get_transaction","params":{"id":"bbea1d35998433e534e8b57f0945c32d1bbd3bd0","include_reversible":"true"}}' https://hive-api.3speak.tv/`

  **Response:**

  

  ```{"jsonrpc":"2.0","error":{"code":-32003,"message":"Assert Exception:false: This node's operator has disabled operation indexing by transaction_id","data":{"code":10,"name":"assert_exception","message":"Assert Exception","stack":[{"context":{"level":"error","file":"account_history_api.cpp","line":226,"method":"get_transaction","hostname":"","timestamp":"2021-10-13T12:05:21"},"format":"false: This node's operator has disabled operation indexing by transaction_id","data":{}}]}},"id":5}```

  

# Transaction times

---

| header | header |
| ------ | ------ |
| https://api.hive.blog | ~960ms |
| https://anyx.io | ~950ms avg |
| https://api.openhive.network | ~450ms |
| http://api.deathwing.me | 200ms avg |



Note that these tests are obviosly not done using multiple locations.

The commands used to test are here https://gitlab.com/PBSA/peerplays/-/issues/191#note_713042607