Rewrite control module/component for TCP/IP

[bmegli]

• [x] design simple protocol
• [x] implement module
• [x] implement component

This currently works on UDP. This protocol is not suitable for that. There are no guarantees that all the packets arrive. Protocol messages should have variable length. The connection should be monitored. Transition to TCP/IP is necessary.

[bmegli]

In proof-of-concept UDP implementation it works as:

enum Commands {ENABLE=0, DISABLE=1, DISABLE_ALL=3, ENABLED=4, DISABLED=5, FAILED=6 };

struct control_packet
{
    uint64_t timestamp_us;
    int16_t command;
    int16_t creation_delay_ms;
    char unique_name[MODULE_NAME_WITH0_MAX];
    char call[MODULE_CALL_WITH0_MAX];
};

With:

• ENABLE=0, DISABLE=1, DISABLE_ALL=3 component -> module communication
• ENABLED=4, DISABLED=5, FAILED=6 module -> component communication

[bmegli]

The TCP/IP protocol proposal (v1) for control module/component:

Commands

• positive for component -> module
• negative for module -> component

  enum Commands {KEEPALIVE=0, ENABLE=1, DISABLE=2, DISABLE_ALL=3, ENABLED=-1, DISABLED=-2, FAILED=-3 };

Message Header

12 bytes with:

• timestamp_us, 8 bytes, uint64_t
• protocol_version, 1 byte, uint8_t, here it's 1
• command, 1 byte, int8_t
• payload_length 2 bytes, uint16_t (not including header)

Message Payload

Attributes

• attribute, 1 byte, uint8_t
• length, 1 byte, uint8_t
• data, byte size in length, interpretation varies

Attribute Data Types:

• string (ascii/utf8, length with '\0', data with '\0' character)
• u16 (2 bytes, network order, uint16_t)
• i32 (4 bytes, network order, u2 int32_t)

enum Attributes {UNIQUE_NAME=0, CALL=1, CREATION_DELAY_MS=2, RETURN_VALUE=3}
// with types string, string, u16, i32

Messages (both ways)

KEEPALIVE

empty payload

Messages (component -> module)

ENABLE

• unique_name (string)
• call (string)
• creation_delay_ms (u16)

DISABLE

• unique_name (string)

DISABLE_ALL

empty payload

Messages (module -> component)

ENABLED

• unique_name (string)

DISABLED

• unique_name (string)

FAILED

• unique_name (string)
• return value (i32)

Additional Info

• order of attributes in message is mandatory (simple parsing)
• downwards compatible (if attribute is not known by application it has to be ignored)

[bmegli]

The module side was implented in tcp-control branch, not tested yet

[bmegli]

The component side was implented in tcp-control ant tested to work with module side

This only needs some final polishing now.

[bmegli]

Merged