Portability	non-portable
Stability	experimental
Safe Haskell	None

Network.Mom.Patterns.Types

Contents

Conduits
Link Type
Error Handling
Some convenient definitions

Description

Fundamental streaming types

Synopsis

Conduits

type RIO = ResourceT IO Source

The IO Resource transformer. See the conduit package for details

type Source = Source RIO ByteString Source

A stream source

type Sink = Sink ByteString RIO ()Source

A stream sink without return type

type SinkR r = Sink ByteString RIO rSource

A stream sink wit return type

type Conduit o r = ConduitM ByteString o RIO rSource

A conduit that links source and sink applying some transformation to the stream. Input is always ByteString, output and return type may vary.

type Conduit_ = Conduit ByteString ()Source

Simplified Conduit where output is always ByteString and no final value is returned.

streamList :: [ByteString] -> Producer RIO ByteString Source

Streaming the elements of a list

passThrough :: Conduit ByteString ()Source

Pass the stream through without applying any transformation to it

Link Type

data LinkType Source

A zeromq AccessPoint can be bound or connected to its address. Only one peer can bind the address, all other parties have to connect.

Constructors

Bind	Bind the address
Connect	Connect to the address

Instances

Read LinkType
Show LinkType

Error Handling

type OnError_ = Criticality -> SomeException -> String -> IO ()Source

Error handler for all services that are implemented as background services, e.g. servers and brokers. The handler receives the Criticality of the error event, the exception and an additional descriptive string.

A good policy is to terminate or restart the service when a Fatal or Critical error occurs and to continue, if possible, on a plain Error. The error handler may perform additional, user-defined actions, such as logging the incident or sending an SMS.

data Criticality Source

Indicates criticality of the error event

Constructors

Error	The current operation (e.g. processing a request) has not terminated properly, but the service is able to continue; the error may have been caused by a faulty request or other temporal conditions.
Critical	The event has impact on the process, leaving it in an unkown state.
Fatal	The service cannot recover and will terminate

Instances

Eq Criticality
Ord Criticality
Read Criticality
Show Criticality

data StreamException Source

Stream Exception

Constructors

SocketExc String	low-level error
IOExc String	IO error
ProtocolExc String	Protocol error
AppExc String	Application-defined error
Ouch String	Internal error, indicating a code error in library