You asked for four tasks:
- Reading Excel / XML files on Linux
- Store structure up to new line: don't know what that means. If you mean handling data row wise: That should be provided by the used Excel reader.
- Convert data into TLV format: this is part of another step not mentioned by you: Defining a communication protocol. Such a protocol defines how the data to be send via network are organised. It usually contains a header with an identifier and general information followed by one or more payload sections (which might have their own header and use TLV for the data)
- Client - server applications: there are many examples in the net
As you can see you have four main tasks:
- Reading Excel / XML files: select a library
- Protocol definition: create your own or use an existing one (e.g. XML)
- Protocol implementation: depends on how data are provided by the reader library
- Sockets: server and client code