Publishing: Publishers

There are three publishers you can use to send data.

• TableSync::Publishing::Single - sends one row with initialization.
• TableSync::Publishing::Batch - sends a batch of rows with initialization.
• TableSync::Publishing::Raw - sends raw data without checks.

Single

TableSync::Publishing::Single - sends one row with initialization.

This is a publisher called by TableSync.sync(self).

Expected parameters:

• object_class - class (model) used to initialize published object
• original_attributes - attributes used to initialize object_class with
• debounce_time - minimum allowed time between delayed publishings
• event - type of event that happened to the published object (create, update, destroy); update by default

What it does (when uses #publish_now):

• takes in the original_attributes, object_class, event
• constantizes object_class
• extracts the primary key (needle) of the object_class from the original_attributes
• queries the database for the object with the needle (for update and create) or initializes the object_class with original_attributes (for destroy)
• constructs routing_key using routing_key_callable and #attributes_for_routing_key (if defined)
• constructs headers using headers_callable and #attributes_for_headers (if defined)
• publishes Rabbit message (uses attributes from queried/initialized object as data)
• sends notification (if set up)

What it does (when uses #publish_later):

• takes in the original_attributes, object_class, debounce_time, event
• serializes the original_attributes, silently filters out unserializable keys/values
• enqueues (or skips) the job with the serialized_original_attributes to be performed in time according to debounce
• job (if enqueued) calls TableSync::Publishing::Single#publish_now with serialized_original_attributes and the same object_class, debounce_time, event

Serialization

Currently allowed key/values are: NilClass, String, TrueClass, FalseClass, Numeric, Symbol.

Job

Job is defined in TableSync.single_publishing_job_class_callable as a proc. Read more in Configuration.

Example #1 (send right now)

  TableSync::Publishing::Single.new(
    object_class: "User",
    original_attributes: { id: 1, name: "Mark" },
    debounce_time: 60, # useless for #publish _now, can be skipped
    event: :create,
  ).publish_now

Example #2 (enqueue job)

  TableSync::Publishing::Single.new(
    object_class: "User",
    original_attributes: { id: 1, name: "Mark" }, # will be serialized!
    debounce_time: 60,
    event: :update,
  ).publish_later

Batch

• TableSync::Publishing::Batch - sends a batch of rows with initialization.

Expected parameters:

• object_class - class (model) used to initialize published objects
• original_attributes - array of attributes used to initialize object_class with
• event - type of event that happened to the published objects (create, update, destroy); update by default
• routing_key - custom routing_key
• headers - custom headers

What it does (when uses #publish_now):

• takes in the original_attributes, object_class, event, routing_key, headers
• constantizes object_class
• extracts primary keys (needles) of the object_class from the array of original_attributes
• queries the database for the objects with needles (for update and create) or initializes the object_class with original_attributes (for destroy)
• constructs routing_key using routing_key_callable (ignores #attributes_for_routing_key) or uses routing_key if given
• constructs headers using headers_callable (ignores #attributes_for_headers) or uses headers if given
• publishes Rabbit message (uses attributes from queried/initialized objects as data)
• sends notification (if set up)

What it does (when uses #publish_later):

• takes in the original_attributes, object_class, event, routing_key, headers
• serializes the array of original_attributes, silently filters out unserializable keys/values
• enqueues the job with the serialized_original_attributes
• job calls TableSync::Publishing::Batch#publish_now with serialized_original_attributes and the same object_class, event, routing_key, headers

Serialization

Currently allowed key/values are: NilClass, String, TrueClass, FalseClass, Numeric, Symbol.

Job

Job is defined in TableSync.batch_publishing_job_class_callable as a proc. Read more in Configuration.

Example #1 (send right now)

  TableSync::Publishing::Batch.new(
    object_class: "User",
    original_attributes: [{ id: 1, name: "Mark" }, { id: 2, name: "Bob" }],
    event: :create,
    routing_key: :custom_key,   # optional
    headers: { type: "admin" }, # optional
  ).publish_now

Example #2 (enqueue job)

  TableSync::Publishing::Batch.new(
    object_class: "User",
    original_attributes: [{ id: 1, name: "Mark" }, { id: 2, name: "Bob" }],
    event: :create,
    routing_key: :custom_key,   # optional
    headers: { type: "admin" }, # optional
  ).publish_later

Raw

• TableSync::Publishing::Raw - sends raw data without checks.

Be carefull with this publisher. There are no checks for the data sent. You can send anything.

Expected parameters:

• object_class - model
• model_name - name of model, which will be insterted to the message payload. If nil, object_class will be used instead
• original_attributes - raw data that will be sent
• event - type of event that happened to the published objects (create, update, destroy); update by default
• routing_key - custom routing_key
• headers - custom headers

What it does (when uses #publish_now):

• takes in the original_attributes, object_class, event, routing_key, headers
• constantizes object_class
• constructs routing_key using routing_key_callable (ignores #attributes_for_routing_key) or uses routing_key if given
• constructs headers using headers_callable (ignores #attributes_for_headers) or uses headers if given
• publishes Rabbit message (uses original_attributes as is)
• sends notification (if set up)

Example

  TableSync::Publishing::Raw.new(
    object_class: "User",
    original_attributes: [{ id: 1, name: "Mark" }, { id: 2, name: "Bob" }],
    event: :create,
    routing_key: :custom_key,   # optional
    headers: { type: "admin" }, # optional
  ).publish_now