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EvClient interface enables:

  1. Create and destroy EvClient objects.

  2. Connect to and disconnect from event server.

  3. Create and send event message to the server.

Event Server Interface

EvServer interface enables:

  1. Create and destroy a single EvServer object.

  2. Accept incoming EvClient connections.

  3. Receive transmitted EVENTS from the clients.

  4. Process received EVENTS (collecting, reformatting, logging, etc.).

  5. Send formatted EVENTS via MQTT channel.

Events

Requirements

Events transmitted to the remote subscriber must be uniquely identifiable and well formatted. Each EVENT message must contain event CATEGORY and SOURCE (the origin of event) information. Event CATEGORY must define group, phase, and step for this event measures (e.g., DHCP client events), whereas SOURCE defines the process which owns and handles this event AND/OR network interface name this event belongs to.

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EVENT object consists of following fields resulting from the above description:

ID

Field name

Data type

Description

1

TIME

Unix time stamp

UTC time with 1 sec resolution

2

MSEC

Integer

Millisecond part of the event time in 0..999 (optional)

3

CAT

Enumeration list

Event category

4

SOURCE

String

The origin of this event: process, network interface, other.

5

SEQ

String

Event sequence information: ONE or START, ... , STOP

6

MSG

String

Event message

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Implementation of this event-based time measurement system in OpenSync firmware software can be divided into four stages.

  1. Event client shared library for EvClient objects with use of Protocol Buffers schema

  2. Event server for EvServer object

  3. MQTT transmitting channel logic

  4. Generation of EVENTS in the embedded software with use of EvClient library

Event client library

  1. Definition of Protocol Buffer schema for EVENT object / message

  2. Simple API to create, destroy client objects, connect to event server, create and send events to the server

  3. Client library internally take care of time stamp insertions, protobuf encapsulation and sending

  4. Client object shall enable logging of EVENTS in the local logging system with OVSDB configuration

Event Server

Event server is enabled using an OVSDB configuration.

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This part of implementation includes the following steps:

  1. Identification of all events for time measurement with categorization, sequence and source definition

  2. Updating of event category enumeration list in the protobuf schema

  3. Identification of processes (OpenSync managers) using which the events are generated

  4. Generation of events in selected processes using the EvClient usage pattern

EvClient Usage Pattern

  1. Add initialization code for creation of global EvClient object connected to EvServer.

  2. Insert events identified by Category, Source and Sequence in the proper places of code

Limited use of QM

The QM client-server protocol design is focused on peer-to-peer connection and uses stream sockets. This approach is not suitable for the “many-clients-to-one-server” communication topology. Datagram sockets are therefore used for this purpose instead.

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