Holumbus.Distribution.DNode.Base

Version : 0.1

The main module for the implementation of the distributed data structures. It contains the DNode-datatype which is needed to register new local and remote resources. The main datatypes (Ids, Handlers, etc.) are also defined here.

The module should only be used from within this library. User applications should refer to Holumbus.Distribution.DNode.

datatypes

data DistributedException

The exception type, used by distributed communication

Constructors

DistributedException

Fields

distEx_msg :: String

the message of the exception

distEx_fct :: String

the function in which the exception was thrown

distEx_mod :: String

the module in which the exception was thrown

Instances

Show DistributedException

Typeable DistributedException

Exception DistributedException

data DNodeConfig

The configuration of a DNode. You need it to create a DNode and you can use this data type it to alter its properties. This type is public to allow users to create their own configuration.

Constructors

DNodeConfig

Fields

dnc_Name :: String

dnc_MinPort :: Int

dnc_MaxPort :: Int

dnc_AccessDelay :: Int

dnc_PingDelay :: Int

Instances

Show DNodeConfig

defaultDNodeConfig :: String -> DNodeConfig

A good default configuration. To create an unnamed node, just leave the string empty.

data DNodeId

The DNode identifier. Every DNode has an Id, this could be named or randomly created. The id could not be used to address a DNode directly over a Network connection because the physical references are missing. The DNodeId is meant to create a declarative reference which could be used to lookup purposes. Think of the DNodeId as a domain name, without a DNS-Server to resolve the physical address, it is worthless to establish a communication.

Instances

Eq DNodeId

Ord DNodeId

Show DNodeId

Binary DNodeId

mkDNodeId :: String -> DNodeId

Use this to make a new DNodeId from a String

data DNodeAddress

The DNode address.

Instances

Eq DNodeAddress

Ord DNodeAddress

Show DNodeAddress

Binary DNodeAddress

mkDNodeAddress :: String -> HostName -> Int -> DNodeAddress

use this to make a new DNodeAddress

data DHandlerId

The Id of a handler, is needed to stop the handler from further execution.

Instances

Eq DHandlerId

Ord DHandlerId

data DResourceType

The ressouce type, it is used to separate between different kinds of resources. The resource type is generated by the programmer of a resource

Instances

Eq DResourceType

Ord DResourceType

Show DResourceType

Binary DResourceType

mkDResourceType :: String -> DResourceType

data DResourceId

The DResource Id.

Instances

Eq DResourceId

Ord DResourceId

Show DResourceId

Binary DResourceId

data DResourceAddress

The DResource address

Instances

Eq DResourceAddress

Ord DResourceAddress

Show DResourceAddress

Binary DResourceAddress

mkDResourceAddress :: DResourceType -> String -> String -> DResourceAddress

type DResourceDispatcher = DNodeId -> Handle -> IO ()

The DResource callback functions

data DResourceEntry

The container for the DResources

Constructors

DResourceEntry

Fields

dre_Dispatcher :: DResourceDispatcher

Instances

Show DResourceEntry

Initializing and Deinitializing of the local node

initDNode :: DNodeConfig -> IO DNodeId

Initializes the DNode of the program. You have to call this function once BEFORE you can use other functions.

deinitDNode :: IO ()

deinitializes a DNode

adding, deleting other nodes

addForeignDNode :: DNodeAddress -> IO ()

Add a foreign DNode to the list of known DNodes. Only DNodes in this list could be reached by the local node.

delForeignDNode :: DNodeId -> IO ()

removes a foreign DNode entry. You should clean up the foreign DNode entries.

checking other nodes and resources

checkForeignDNode :: DNodeId -> IO Bool

Manually Checks, if another DNode is reachable. Returns true if this is the case, otherwise false. Always returns, does not throw an exception caused by network failures.

addForeignDNodeHandler :: Bool -> DNodeId -> DHandlerFunction -> IO (Maybe DHandlerId)

Adds a handler function which periodically checks the existences (or non-existence) of other DNodes. The first parameter indicates the type of the handler. If you want to install a handler which is fired when a Node becomes reachable (positive trigger), it needs to be true. If you want to monitor the event when a specific node disappears, pass false.

addForeignDResourceHandler :: Bool -> DResourceAddress -> DHandlerFunction -> IO (Maybe DHandlerId)

Adds a handler function which periodically checks the existences (or non-existence) of resources on other DNodes. The first parameter indicates the type of the handler. If you want to install a handler which is fired when a Node becomes reachable (positive trigger), it needs to be true. If you want to monitor the event when a specific node disappears, pass false.

delForeignHandler :: DHandlerId -> IO ()

Deletes a Handler from the system, will not be called anymore.

needed by the resources

genLocalResourceAddress :: DResourceType -> String -> IO DResourceAddress

addLocalResource :: DResourceAddress -> DResourceEntry -> IO ()

delLocalResource :: DResourceAddress -> IO ()

delForeignResource :: DResourceAddress -> IO ()

safeAccessForeignResource :: DResourceAddress -> (Handle -> IO a) -> IO a

unsafeAccessForeignResource :: DResourceAddress -> (Handle -> IO a) -> IO a

getByteStringMessage :: Handle -> IO ByteString

Reads data from a stream. We define, that the first line of the message is the message header which tells us how much bytes we have to read.

putByteStringMessage :: ByteString -> Handle -> IO ()

Puts a bytestring to a handle. But to make the reading easier, we write the length of the data as a message-header to the handle, too.

getDNodeData :: IO DNodeData