model

Documentation

Index

• Constants
• type Command
• type Document
• type Error
  • func NewError(code int16, msg string) *Error
• type Event
• type EventMeta
• type EventStoreQuery
• type LogEntry

Constants

const DatabaseError int16 = 2

DatabaseError is when some operation related to Database, such as insert or find, goes wrong and the task cannot proceed.

const InternalError int16 = 1

InternalError represents an error when something goes wrong, and its our fault.

const UserError int16 = 3

UserError occurs when there's an error because of user's action. An example would be providing invalid input.

Types

type Command

type Command struct {
	// Action for which the command is being produced.
	Action string `json:"action,omitempty"`

	// CorrelationID can be used to track Command's source or reason why it as generated.
	CorrelationID uuuid.UUID `json:"correlationID,omitempty"`

	// Data required for invoking the command.
	Data []byte `json:"data,omitempty"`

	// ResponseTopic is the Messaging-Topic on which the
	// response from processing the command should be sent.
	ResponseTopic string `json:"responseTopic,omitempty"`

	// Source is the name of the service which created the command.
	Source string `json:"source,omitempty"`

	// SourceTopic is the Messaging-Topic on which the Command was produced.
	SourceTopic string `json:"sourceTopic,omitempty"`

	// Timestamp is the time in Unix-milliseconds when this Command was generated.
	Timestamp int64 `json:"timestamp,omitempty"`

	// TTLSec is the Time-To-Live in seconds.
	// The Command should not be processed if current-time exceeds Timestamp+TTLSec.
	TTLSec int32 `json:"ttlSec,omitempty"`

	// UUID is the unique-identifier for Command.
	UUID uuuid.UUID `json:"uuid,omitempty"`
}

Command can be used to invoke a procedure in another service.

type Document

type Document struct {
	// CorrelationID can be used to track Document's source or reason why it as generated.
	CorrelationID uuuid.UUID `json:"correlationID,omitempty"`

	// Data contained by Document.
	Data []byte `json:"data,omitempty"`

	// Error occurred while processing the Input.
	// Convert errors to strings, this is just an indication that
	// something went wrong, so we can signal/display-error to end-
	// user. Blank Error-string means everything was fine.
	Error string `json:"error,omitempty"`

	// ErrorCode can be used to identify type of error.
	ErrorCode int16 `json:"errorCode,omitempty"`

	// Source is the name of the service which created the command.
	Source string `json:"source,omitempty"`

	// Topic on which the document should be produced.
	Topic string `json:"topic,omitempty"`

	// UUID is the V4-UUID Document-Identifier.
	UUID uuuid.UUID `json:"uuid,omitempty"`
}

Document can be used to transfer data between services.

type Error

type Error struct {
	Code    int16  `json:"code,omitempty"`
	Message string `json:"message,omitempty"`
}

Error describes any error.

func NewError

func NewError(code int16, msg string) *Error

NewError is a convenient awy to create an Error-instance.

type Event

type Event struct {
	// Action that was performed by the Event.
	Action string `cql:"action,omitempty" json:"action,omitempty"`

	// AggregateID for Aggregate associated with the Event.
	AggregateID int8 `cql:"aggregate_id,omitempty" json:"aggregateID,omitempty"`

	// CorrelationID can be used to track Event's source or reason why it as generated.
	CorrelationID uuuid.UUID `cql:"correlation_id,omitempty" json:"correlationID,omitempty"`

	// Data contained by event.
	Data []byte `cql:"data,omitempty" json:"data,omitempty"`

	// NanoTime is the time in nanoseconds since Unix-epoch to when the event was generated.
	NanoTime int64 `cql:"nano_time,omitempty" json:"nanoTime,omitempty"`

	// Source is the name of service responsible for generating Event.
	Source string `cql:"source,omitempty" json:"source,omitempty"`

	// UserUUID is the V4-UUID of the user who generated the event.
	UserUUID uuuid.UUID `cql:"user_uuid,omitempty" json:"userUUID,omitempty"`

	// UUID is the V4-UUID unique-indentifier for event.
	UUID uuuid.UUID `cql:"uuid,omitempty" json:"uuid,omitempty"`

	// Version for events as processed for aggregate-projection.
	// This is incremented by the aggregate itself each time it updates its state.
	Version int64 `cql:"version,omitempty" json:"version,omitempty"`

	// Year bucket is the year in which the event was generated.
	// This is used as the partitioning key.
	YearBucket int16 `cql:"year_bucket,omitempty" json:"yearBucket,omitempty"`
}

Event refers to any change in system, such as insertion of some data.

type EventMeta

type EventMeta struct {
	// AggregateID corresponds to AggregateID in
	// event-store and ID in aggregate-projection.
	AggregateID int8 `cql:"aggregate_id,omitempty" json:"aggregateID,omitempty"`

	// AggregateVersion tracks the version to be used
	// by new events for that aggregate.
	AggregateVersion int64 `cql:"aggregate_version,omitempty" json:"aggregateVersion,omitempty"`

	// PartitionKey is the partitioning key for events_meta table.
	PartitionKey int8 `cql:"partition_key,omitempty" json:"partitionKey,omitempty"`
}

EventMeta contains the information about hydrating Aggregate-Projections. The AggregateVersion tracks the version to be used by new events for that aggregate. This difference between the aggregate-projection version and AggregateVersion gives us the versions of the events yet to be applied to the aggregate projection.

type EventStoreQuery

type EventStoreQuery struct {
	// AggregateID is the id for aggregate whose events are to be fetched
	AggregateID int8 `json:"aggregateID,omitempty"`

	// AggregateVersion is the highest version of events that have been
	// already fetched by the aggregate. The event-store will be queried
	// for events greater than this version.
	AggregateVersion int64 `json:"aggregateVersion,omitempty"`

	// CorrelationID can be used to "identify" responses, such as checking
	// if the response is for some particular request.
	// Including CorrelationID will result in inclusion of this ID in any
	// responses generated as per result of event's processing.
	CorrelationID uuuid.UUID `json:"correlationID,omitempty"`

	// Topic on which Events are to be received.
	Topic string `json:"topic,omitempty"`

	// YearBucket is the partition-key for Event-Table.
	YearBucket int16 `json:"yearBucket,omitempty"`

	// UUID is the V4-UUID Query-Identifier.
	// This can be used to "identify" responses.
	UUID uuuid.UUID `json:"uuid,omitempty"`
}

EventStoreQuery can be used to fetch later events than the specified version.

type LogEntry

type LogEntry struct {
	// Action describes "what was happening" when this entry was created.
	Action string `json:"action,omitempty"`

	// Description of what happened, can also be an error description.
	Description string `json:"description,omitempty"`

	// ErrorCode is just to inform the kind or classification of error.
	// The actual error should be part of description.
	ErrorCode int `json:"errorCode,omitempty"`

	// Level is the severity-level, that is, info, warning, or error.
	Level string `json:"level,omitempty"`

	// ServiceName is the service associated with the log.
	ServiceName string `json:"serviceName,omitempty"`
}

LogEntry describes "what's currently happening" for logging purposes.