Site Domain Center (sdc)

Description

A repository of domain entities.
Provides other roles with access to data to organize processes. Some data is subject to pre-calculation within the role.

Divided into microservices by domain. Data is automatically synchronized between sites serving the domain.
Reserved in Active-Passive mode. Scaled by domain tree partitioning.

Table 1. System Characteristics

Code

sdc

Mode of operation

Storage, service

Backup mode

Active-Passive

Types of sites

All the workers

Layer

Business logic

Placement

Internal

Saving and restoring state on reboot

Yes

appendix

era_dc

Own storage

ODB Mnesia

Limitations

  • Cannot be located on the master site, instead the role is used on the master site mdc.

  • Should be located at every work site.

  • Data synchronization between sites is done through the mdc role on the master site with a cumulative frequency of up to 1 minute.

Parameters

Description of columns in the table

Table 2. Parameters
Name Type Default Description

name

str

required

Name. May consist of Latin letters and numbers, must begin with a letter.

roletype

str

required

Role Type. Possible values: "sdc".

iface

str

required

The alias of the server network interface on which the roles will interact internally with each other.

ext

json

empty

Additional role options. Contains a json object or list.

enabled

bool

empty

Role activity flag. When set to false, the role does not participate in validation and is not started.

group

int

required

Group Number.
As part of horizontal scaling, a role can be divided into multiple groups on a site, with only one instance active in each group and the rest reserved.
Responsibilities between groups are shared across domain sets. Together, all groups maintain a complete domain set. All roles in the same group must have the same responsibility.
Integer from 1 to 9999999.

order

int

required

The order of a role instance within a group.
Defines in what order the flow in the mode will take place Active-Passive.

include_domains

array<str>

empty

A list of domain names served by this group.
Any domain of any level can be specified. Specifying a domain causes its subdomain tree to be served on this group and not on other role groups, excluding only those branches mentioned in other groups.
Collectively, all role groups on a site serve a complete domain tree.

*max_loading_domains"

int

4

Limit the number of domains that can be loaded at the same time.
Comes in handy in systems with a large number of domains.
It is used to limit the CPU load during microservice reboot.

Configuration example

The configuration is managed in an application available to master domain administrators. The application hides the full content of the configuration, but it is nevertheless accessible via the API.

The configuration contains a section to describe all instances of all roles. Parameters are defined for each specific role instance.

Example node
{
  "name": "sdc1",
  "roletype": "sdc",
  "iface": "eth0",

  "group": 21020,
  "order": 1
}
json

See also