bbfdm/docs/guide/dm-service.md

Data Model Micro-Service (dm-service

dm-service daemon is designed to expose a specific module or sub-tree of a data model as datamodel micro-service.

Note: The command outputs shown in this document are examples and may vary depending on your device and configuration.

Concepts and Workflow

dm-service daemon gets started by /etc/init.d/bbfdm.services service. This init script reads input from bbfdm UCI file, particularly from micro_services section. It then parses each micro-service configuration file located in /etc/bbfdm/micro_services/. Each micro-service’s configuration, written in JSON, is used to start the service using the APIs provided by libbbfdm-ubus and libbbfdm-api libraries.

dm-service daemon use libbbfdm-api library to traverse the datamodel tree defined by DotSo or JSON plugin located in /usr/share/bbfdm/micro_services/$micro-service-name{.so,.json} and its plugins defined in /usr/share/bbfdm/micro_services/$micro-service-name/.

dm-service daemon use libbbfdm-ubus library to expose datamodel over UBUS.

Datamodel micro-service is nothing but another bbfdmd instance running with smaller data sub-set, and can be identified at runtime by running a ps command

# ps|grep dm-service
12163 root      7664 S    {dm_bulkdata} /usr/sbin/dm-service -m bulkdata -l 3
12164 root      7620 S    {dm_ddnsmngr} /usr/sbin/dm-service -m ddnsmngr -l 3
12165 root      7736 S    {dm_dhcpmngr} /usr/sbin/dm-service -m dhcpmngr -l 3
12166 root      7760 S    {dm_dnsmngr} /usr/sbin/dm-service -m dnsmngr -l 3
12167 root      7800 S    {dm_ethmngr} /usr/sbin/dm-service -m ethmngr -l 3

Each dm-service instance must be started with -m input to define its service name and run its module(sub-tree) datamodel. These micro-services exposed their own ubus objects

# ubus list bbfdm.*
bbfdm.Bridging
bbfdm.BulkData
bbfdm.DHCPv4_DHCPv6
bbfdm.DNS

When a datamodel started as micro-service, it looks/waits for bbfdm UBUS object(added by main bbfdmd process), once its available micro-service registers with the main bbfdmd process by calling the 'service' method

# ubus -v list bbfdm
'bbfdm' @e970413c
        "service":{"cmd":"String","name":"String","parent_dm":"String","objects":"Array"}

Input and output Schema(s)

dm-service is used to expose sub-tree using different ubus object, UBUS guide and schema for datamodel micro-services

• datamodel micro-service
• datamodel micro-service schema

Apart from these, datamodel micro-services can also be configured by updating their input files directly at runtime, micro-service input files present in /etc/bbfdm/micro_services/ in CPE.

A typical micro-service input file looks like below:

{
  "daemon": {
    "enable": "1",
    "service_name": "netmngr",
    "config": {
      "loglevel": "3"
    },
    "output": {
      "name": "Network"
    }
  }
}

Ubus methods

Following are the UBUS methods exposed by dm-service process:

# ubus -v list bbfdm.Network
'bbfdm.Network' @9dc36737
	"get":{"path":"String","paths":"Array","maxdepth":"Integer","optional":"Table"}
	"schema":{"path":"String","paths":"Array","first_level":"Boolean","optional":"Table"}
	"instances":{"path":"String","paths":"Array","first_level":"Boolean","optional":"Table"}
	"set":{"path":"String","value":"String","datatype":"String","obj_path":"Table","optional":"Table"}
	"operate":{"command":"String","command_key":"String","input":"Table","optional":"Table"}
	"add":{"path":"String","obj_path":"Table","optional":"Table"}
	"del":{"path":"String","paths":"Array","optional":"Table"}

Note1: optional table are present in all methods and it supports below options:

"optional":{"proto":"String", "format":"String"}

• proto in each method specify the data-model prototype('cwmp', 'usp') to use, if not provided default data-model will be used.

• format could be 'raw' or 'pretty', to specify the format to use as output, if not provided 'pretty' format will be used.

Note2: first_level true means only get next level objects and false means get all objects recursively

Note3: maxdepth is measured on max number of .(Dot) present in object name

Note4: Check ubus schema document for more details

Pros and Cons of Data Model Micro-Service

Data model micro-service is nothing but running a partial datamodel sub-set with another instance of bbfdmd binary.

Benefit:

• Instead of having a huge datamodel tree, it split the tree based on modules, which reduce the cost of operation on the tree
• Resolves one point failure, if any datamodel micro-service not working correctly it only affects that specific module, not the rest of the tree
• Moving datamodel code to module repo, brings the service layer and datamodel layer closer, which lowers the possibilities of wrong mapping
• Possible to use lightweight dm-service inside containers with json plugin for Container service management
• Possible to impose CPU/Memory restrictions or even run it in a procd jail to limit the host resource access

Cons:

• It requires to execute a dm-service instance each module, so takes bit more resouces
• Resolving of complex datamodel paths, like datamodel references of external modules (ex: bridgemngr refers to wifi layer from wifidmd) cost more on IPC

When not to use micro-service:

• Its suggested not to use datamodel micro-service specially in the devices which are having very less resources(in terms of memory/cpu), or
• On devices which have high IPC cost over ubus

How to Use micro-service

Manually configuring and starting a micro-services requires multiple steps, but its made simple by using bbfdm.mk compile time helper utility. To launch a datamodel definition as a datamodel micro-service, user need to install the datamodel definition/plugin using

BBFDM_INSTALL_MS_DM API from bbfdm.mk

bulkdata/Makefile:      $(BBFDM_INSTALL_MS_DM) $(PKG_BUILD_DIR)/bbf_plugin/bulkdata.json $(1) $(PKG_NAME)
ddnsmngr/Makefile:      $(BBFDM_INSTALL_MS_DM) $(PKG_BUILD_DIR)/src/libddnsmngr.so $(1) $(PKG_NAME)

Please check bbfdm.mk documentation for more details.

In Devices, datamodel micro-services started and managed by /etc/init.d/bbfdm.services init script, which reads the global micro-service related configuration from bbfdm uci file, and reads module specific configuration for each module's input file present in /etc/bbfdm/micro_services/ directory.

In plugins approach, the 3rd party datamodel gets attached to main bbfdm process, which further increases nodes in main datamodel tree, which overtime become a huge tree, results in slower turn around service time for the APIs. Also, any unhandled fault in plugin result in segfault in main bbfdmd process, which takes down the whole tree along with plugin, resulting in complete failure from cwmp and USP, with micro-services plugins runs as an individual processes, so impact of fault limited to its own micro-service only.

Micro-service approach, disintegrate the plugins further and run them as individual daemons with the help of "bbfdmd" "-m" command line options.

Datamodel debugging tools

To configure the log_level in micro-service, update the loglevel module json file,

# cat /etc/bbfdm/micro_services/netmngr.json 
{
  "daemon": {
    "enable": "1",
    "service_name": "netmngr",
    "config": {
      "loglevel": "7"
    },
    "output": {
      "name": "Network"
    }
  }
}

and then restart the bbfdm.services