# 12. Comparison of C++ Formulas and WebSocket API
Extending the robot's functionality is possible in two ways: using С++ formulas or the WebSocket API. These are different mechanisms designed for different purposes, although they share some similarities. For user convenience, the table below compares С++ formulas and WebSocket API across several key parameters.
| FEATURE | С++ FORMULAS | WEBSOCKET API |
|---|---|---|
| Programming Language | C++ | Any programming language. It is recommended to use high-level languages with standard libraries for WebSocket protocol support |
| Capabilities | Limited. There are restrictions on formula source code length. You can retrieve financial instrument data and modify certain portfolio parameters. User fields, not used in the main algorithm, are provided for use in formulas. File system access and network operations (e.g., socket creation) are prohibited. Time-consuming operations are strongly discouraged. No access to external data sources (databases, Excel sheets, etc.) is possible | Full. You can automate everything available through the platform’s web interface. No architectural limitations or restrictions on using external data sources |
| Interactions Between Portfolios | Possible only between portfolios within the same robot, and only if the accessed portfolios have the Shared formulas flag enabled | One application can interact with all available portfolios regardless of which robot they belong to |
| Execution Method | Native code, compiled into a dynamically loaded library that runs in the same thread as the robot’s main algorithm | Separate application running on an external server |
| Impact on Robot Performance | Can slow down the robot, as formulas are an integral part of the main algorithm and run in the same thread | No impact on robot performance, as calculations occur independently and in parallel |
| Data Access Speed | Formulas are recalculated immediately after any order book update triggers the main pricing calculation. No rate limits apply to data accessible within formulas | Requires sending explicit requests to get or modify data; subject to rate limits . When subscribed to data updates, the server sends changes in batches at a specific frequency , not on every change |
| Fault Tolerance | Errors in formulas can cause the entire robot to crash | A crash in the external application affects only its own calculations; the robot continues trading according to its internal logic and last received parameters. Note that automation via WebSocket carries the risk of connection loss — in such cases, the robot will continue trading with the last applied settings |