KubeMQ Targets

KubeMQ Targets connects KubeMQ Message Broker with external systems and cloud services.

KubeMQ Targets allows us to build a message-based microservices architecture on Kubernetes with minimal efforts and without developing connectivity interfaces between KubeMQ Message Broker and external systems such as databases, cache, messaging, and REST-base APIs.

Key Features:

• Runs anywhere - Kubernetes, Cloud, on-prem, anywhere

• Stand-alone - small docker container / binary

• Single Interface - One interface all the services

• Any Service - Support all major services types (databases, cache, messaging, serverless, HTTP, etc.)

• Plug-in Architecture Easy to extend, easy to connect

• Middleware Supports - Logs, Metrics, Retries, and Rate Limiters

• Easy Configuration - simple yaml file builds your topology

Concepts

KubeMQ Targets building blocks are:

• Binding

• Source

• Target

• Request/Response

Binding

Binding is a 1:1 connection between Source and Target. Every Binding runs independently.

binding

Target

Target is an external service that exposes an API allowing interacting and serve his functionalists with other services.

Targets can be Cache systems such as Redis and Memcached, SQL Databases such as Postgres and MySql, and even an HTTP generic Rest interface.

KubeMQ Targets integrate each one of the supported targets and service requests based on the request data.

Source

The source is a KubeMQ connection (in subscription mode), which listens to requests from services and route them to the appropriate target for action, and return a response if needed.

Request / Response

concept

Request

A request is an object that sends to a designated target with metadata and data fields, which contains the needed information to perform the requested data.

Request Object Structure

Field	Type	Description
metadata	string, string object	contains metadata information for action
data	bytes array	contains raw data for action

Example

Request to get a data from Redis cache for the key "log"

{
  "metadata": {
    "method": "get",
    "key": "log"
  },
  "data": null
}

Response

The response is an object that sends back as a result of executing an action in the target

Response Object Structure

Field	Type	Description
metadata	string, string object	contains metadata information result for action
data	bytes array	contains raw data result
is_error	bool	indicate if the action ended with an error
error	string	contains error information if any

Example

Response received on request to get the data stored in Redis for key "log"

{
  "metadata": {
    "result": "ok",
    "key": "log"
  },
  "data": "SU5TRVJUIElOVE8gcG9zdChJRCxUSVRMRSxDT05URU5UKSBWQUxVRVMKCSAgICAgICAgICAgICAgICAgICAgICA"
}

Middlewares

In bindings configuration, KubeMQ Bridges supports middleware setting for each pair of source and target bindings.

These properties contain middleware information settings as follows:

Logs Middleware

KubeMQ Bridges supports level based logging to console according to as follows:

Property	Description	Possible Values
log_level	log level setting	"debug","info","error"
		"" - indicate no logging on this bindings

An example for only error level log to console:

bindings:
  - name: sample-binding 
    properties: 
      log_level: error
    sources:
    ......

Retry Middleware

KubeMQ Bridges supports Retries' target execution before reporting of error back to the source on failed execution.

Retry middleware settings values:

Property	Description	Possible Values
retry_attempts	how many retries before giving up on target execution	default - 1, or any int number
retry_delay_milliseconds	how long to wait between retries in milliseconds	default - 100ms or any int number
retry_max_jitter_milliseconds	max delay jitter between retries	default - 100ms or any int number
retry_delay_type	type of retry delay	"back-off" - delay increase on each attempt
		"fixed" - fixed time delay
		"random" - random time delay

An example for 3 retries with back-off strategy:

bindings:
  - name: sample-binding 
    properties: 
      retry_attempts: 3
      retry_delay_milliseconds: 1000
      retry_max_jitter_milliseconds: 100
      retry_delay_type: "back-off"
    sources:
    ......

Rate Limiter Middleware

KubeMQ Sources support a Rate Limiting of target executions.

Rate Limiter middleware settings values:

Property	Description	Possible Values
rate_per_second	how many executions per second will be allowed	0 - no limitation
		1 - n integer times per second

An example for 100 executions per second:

bindings:
  - name: sample-binding 
    properties: 
      rate_per_second: 100
    source:
    ......