What systems exist for integrating existing software with other systems?

Question

Software and Internet Services

Good afternoon!
In industrial operation, there is some kind of analytics application that actively uses data from other systems (it can make queries to the database on a schedule or import CSV/XML files).
The problem is that in this application there is practically no possibility of preprocessing data before saving it. And preprocessing is very often required. it is necessary to bring the data to the desired form.
It is not possible to make changes to the application.
I read about solutions like ESB (Enterprise Service Bus), which would somehow fit our tasks, but many products either stand as enterprise solutions or look abandoned for a long time.
Are there any products (preferably free/open-source) that can be used commercially and put on Windows Server?
A typical use case for such a product/system looks like this:

1. This system receives data from an adjacent system
   Predominantly PULL, ie. itself climbs into the database / via API or takes the file. But the option is not ruled out when it may be necessary for the adjacent system to send data (PUSH).
   The main requirement is that the system be able to receive data on its own, according to a schedule or, possibly, by an event (for example, the appearance of a file in a directory).
   
2. The system performs data processing
   Filtering/transforming values ​​(converting dates, removing extra spaces/symbols, joining/separating values ​​of different fields, etc.), converting data to some scheme.
   
3. Existing software takes data from this system
   Preferably PULL, tk. the application's API capabilities are extremely scarce. For example, the system saves the processed data in the database, then the application goes and takes the data from the database of this system.
   

Now, for a couple of cases, we used the Windows Task Scheduler, which launched the PowerShell script (they took the XML file laid out for us, brought it to the desired form and saved it to another directory). But this is extremely inconvenient.

Answer 1

I read about solutions like ESB (Enterprise Service Bus), which would somehow fit our tasks, but many products either stand as enterprise solutions or look abandoned for a long time.

RabbitMQ.

It is not possible to make changes to the application.

Then you have to do very bad things. For example, to climb into the storage of someone else's application.

Answer 2

What systems exist for integrating existing software with other systems?

Programmers who specialize in enterprise automation spend a significant part of their time on what they integrate.
There are simply millions of these systems.
The question is not correct.

Answer 3

In industrial operation

Is it just me breaking the pattern?