Which integration technique would be best for displaying invoice data in real time without requiring updates?

The best technique for displaying invoice data in real time without requiring updates is to launch an external application as a Web tab. This approach allows users to interact with a fully functional external application that can display the most current invoice data, as the external application can directly connect to its own data source in real time. Whether it's retrieving data from a database, web service, or another system, users can view up-to-date information without facing any delays caused by data import processes or synchronization issues.

The utilization of a Web tab effectively integrates external functionality into the Salesforce environment without necessitating continuous updates or manual intervention, allowing for a seamless experience for users while maintaining real-time access to the necessary information. This capability is particularly useful when dealing with dynamic data that frequently changes, such as invoice details.

In contrast, the other integration techniques involve either import processes or display mechanisms that may not be able to provide real-time updates effectively. For example, using APIs or real-time data imports can introduce latency or require periodic refreshes to keep the data up to date. Displaying data through a Visualforce page could also lead to similar issues, as the data might need to be refreshed or re-fetched to ensure its accuracy, which is contrary to the need for real-time access.