Stream Distribution & Routing

Overview

The Stream Distribution & Routing (SDR) consists of two components: Workload Distribution Agent and Workload Routing Agent.

• Workload Distribution Agent

  • It receives stream events initiated by Video Storage Toolkit (VST)

  • It compiles the workloads and evenly distributes them to underlying microservices by invoking their webhooks

  • It writes the distribution mapping into a cache

• Workload Routing Agent

  • It intercepts a HTTP or GPRC call from an upstream caller and extract the stream identifier from the request header

  • It looks up the distribution mapping with the stream identifier

  • it routes requests to the specific processing replica of a microservice

The rule of thumb is that a microservice should be integrated with SDR if it satisfy both of following criteria:

• It needs to notified when a stream event occurs at VST

• It is a stateful service that requires the incoming request to be consistently routed to the same processing replica.

Currently the following services are integrated with SDR: Perception (DeepStream).

Configuration

Parameters to the agent can be passed at install time if necessary. Default parameters are sufficient for functioning of the application on a single node.

List of Parameters

Parameters	Description
WDM_WL_SPEC	Data cache file used for state management
WDM_WL_THRESHOLD	Max number of sensor stream a pod can manage
WDM_CONSUMER_GRP_ID	Unique consumer group ID used to listen for messages from Redis
WDM_WL_OBJECT_NAME	Name of the work load object managed by the agent (statefulset name).
WDM_MAX_REPLICAS	Maximum number of replicas that the agent scale the pods horizontally.
WDM_KFK_BOOTSTRAP_URL	Kafka Server Endpoint, deployed as part of MDX app chart.
WDM_MSG_TOPIC	Topic or key where Redis is publishing the event messages.
WDM_WL_REDIS_SERVER	Address of the Redis server
WDM_WL_REDIS_PORT	Redis server port number
WDM_WL_CONFIG_PORT	REST API Port to send the event message received from VST.
WDM_WL_ADD_URL	REST URL end-point to route the “add” event messages
WDM_WL_DELETE_URL	REST URL end-point to route the “delete” event messages
WDM_TARGET_PORT_MAPPING	A JSON string describing the port mapping to send requests. Eg: {“default”: 8011, “grpc”: 50064}
ENVOY_ROUTE_URL_PREFIX	Prefix for the incoming API request for Envoy to do routing
ENVOY_ROUTE_URL_PREFIX_REWRITE	Proxy rewrite prefix for envoy to send to target pod in the cluster of pods

Configure In Helm Chart

The command options configurable by including the following entries in a helm command values file. However this is not mandatory.

  # Command.values.yaml
metropolis-wdm:
  applicationSpecs:
      agent-deployment:
      containers:
          agent-container:
          resources: {}
          image:
              pullPolicy: IfNotPresent
              repository: nvcr.io/nfgnkvuikvjm/mdx-v1_0/wdm-mdx
              tag: 0.16.0

  workloadSpecs:
      workload:
      wl_data: |
          [
              {
                  "alert_type": "camera_status_change",
                  "created_at": "2023-05-16T21:50:36Z",
                  "event": {
                      "camera_id": "Test_Cam_1",
                      "camera_name": "<sensor-name>",
                      "camera_url": "rtsp://<URL_Path:Port>/",    #### RTSP URL for the sensor
                      "change": "camera_streaming"
                  },
                  "source": "preload"
              }
          ]
      wl_env:
      - name: WDM_WL_SPEC
          value: /wdm/data/data.yaml
      - name: WDM_WL_THRESHOLD
          value: "10"
      - name: WDM_CONSUMER_GRP_ID
          value: wdm-group-1
      - name: WDM_KFK_BOOTSTRAP_URL
          value: mdx-kafka-cluster-kafka-brokers:9092
      - name: WDM_WL_OBJECT_NAME
          value: mdx-ds-app            ##### Stateful set app name to control using SDR.
      - name: WDM_WL_CONFIG_PORT
          value: "9000"
      - name: WDM_MSG_TOPIC
          value: mdx-notification
      - name: WDM_WL_PROXY_URL
          value: /
      - name: WDM_WL_ROUTER
          value: ucf-svc-metropolis-wdm-ds-nginx
      - name: WDM_WL_ROUTER_CONFIG_MAP
          value: wdm-default-nginx
      - name: WDM_WL_REDIS_SERVER
          value: redis-redis-svc
      - name: WDM_WL_REDIS_PORT
          value: "6379"
      - name: ENVOYROUTEHEADER
          value: id
      - name: ENVOY_ROUTE_URL_PREFIX_REWRITE
          value: /
      - name: ENVOY_ROUTE_URL_PREFIX
          value: /
      - name: WDM_WL_ADD_URL
          value: /stream/add
      - name: WDM_WL_ID_FIELD
          value: camera_id
      - name: WDM_WL_DELETE_URL
          value: /stream/remove
      - name: WDM_EVENT_OBJECT_FIELD
          value: event
      - name: WDM_MAX_REPLICAS
          value: "3"
      - name: WDM_TARGET_PORT_MAPPING
          value: '{"default": 9000}'
      - name: WDM_PRELOAD_WORKLOAD
          value: /opt/workload-config/workload
      - name: WDM_MSG_KEY
          value: sensor
      - name: WDM_WL_CHANGE_ID_ADD
          value: camera_streaming
      - name: WDM_MAP_ADD_FIELD
          value: '{"camera_streaming": "camera_add"}'
      - name: WDM_REMAP_EVENT_OBJECT
          value: '{"event": "value"}'
      wl_resources:
          limits: {}
          requests: {}
      wl_units: 1
  xds_cluster_address: metropolis-wdm-agent-deployment-agent-xds-service
  xds_cluster_port: '4000'