TRONamedPipeChannel Class

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Contents

Overview

TRONamedPipeChannel implements a channel that uses Windows Named Pipes to communicate between a client and a server on the same machine or local network.


Location

uRONamedPipeChannel.pas

Implemented interfaces


Properties

ActivateOnDemand

Allows the channel to open the named pipe to the server automatically if needed (true, default) or not (false).



property ActivateOnDemand: Boolean read write


Active

Gets or sets whether the named pipe to the server is currently active (true) or not (false).



property Active: Boolean read write


BufferSize



property BufferSize: integer read write


Busy     (declared in TROTransportChannel)

Informs whether the channel is currently busy executing a remote request (true) or not (false). Most channels (except most notably the TROSuperTCPChannel) are only capable of performing one request at a time; if a second request is attempted while the channel is Busy, an EROChannelBusy exception will be raised.



property Busy: boolean read


CurrentLocator     (declared in TROTransportChannel)

Returns which of the fail-over/load balancing servers configured in the ServerLocators is currently active. Depending on the DispatchOptions defined, this value might change with each request, or only if the current server fails.



property CurrentLocator: TROServerLocator read write


DispatchOptions

Configures the available fail-over and load balancing options provided by the RemObjects SDK. By default, channels are set up to talk to one specific server only. Two independent options are available to provide fail-over and load balancing:

  • Enables fail-over support. If the connection to any given server fails, the channel will automatically keep trying the next server specified in ServerLocators, until a working server is found or all servers have been tried.
  • Enables load-balancing support. Each request dispatched through the channel will go to a different server configured in ServerLocators, resulting in calls being more or less equally distributed over the available servers.

Enabling any of these options obviously requires the server to be implemented in a stateless way, so that it does not depend on all requests from a client going to the same server. This implies using a class factory different from Per-Client and, if sessions are used, a session manager that allows sharing of session state between servers.



property DispatchOptions:


Encryption obsolete     (declared in TROBaseConnection)

This is DES based enscryption, it is obsolete because works only for Delphi. Use message envelope AES Encryption Envelope instead.



property Encryption: TROEncryption read write


FaultToleranceLocatorIdx     (declared in TROTransportChannel)



property FaultToleranceLocatorIdx: integer read write


isProbeMode   protected     (declared in TROTransportChannel)

Returns True if channel is used for probing purposes



property isProbeMode: Boolean read


LoadBalancerLocatorIdx     (declared in TROTransportChannel)



property LoadBalancerLocatorIdx: Integer read write


NetworkByteOrder



property NetworkByteOrder: Boolean read write


OnAfterProbingServer

Fires after the channel is done probing a specific server for availability. You can use this event to check the result of the probing, possibly to update internal data structures or to display server status in the user interface.



property OnAfterProbingServer:


OnAfterProbingServers

Fires after the channel is done probing all servers for availability. You can use this event to check the result of the probing, possibly to update internal data structures or to display server status in the user interface.



property OnAfterProbingServers:


OnBeforeProbingServer

Fires before the channel starts probing a specific server for availability. You can use this event to:

  • check or adjust the server configuration
  • to include/exclude the server from being probed by changing the TROServerLocator.Enabled property.



property OnBeforeProbingServer:


OnBeforeProbingServers

Fires before the channel starts probing all servers for availability. You can use this event:

  • to check or adjust the server configurations
  • to include/exclude individual server from being probed by changing their TROServerLocator.Enabled properties.



property OnBeforeProbingServers:


OnLoginNeeded

Fires if an EROSessionNotFound (or the descendant SessionNotFoundException) exception is raised during the execution of a remote request. This usually indicates that the server cannot authenticate the client or that the session has expired. The most common use for this event is to perform a call to a special Login service provided by the server (possibly after prompting the user to enter username and password), and to set the aRetry parameter to true if login was successful.



property OnLoginNeeded:


OnProgress



property OnProgress:


OnReceiveStream

Fires after a stream with a response message has been received from the server. Use this event handler to inspect and possibly modify the stream, before it continues to be processed by the higher levels of the RemObjects SDK framework.



property OnReceiveStream:


OnSendStream

Fires just as a stream with a request message will be sent to the server. The event handler can inspect and possibly modify the stream, before it continues to be sent off to the server.



property OnSendStream:


OnServerLocatorAssignment



property OnServerLocatorAssignment:


ProbeFrequency

Sets at what intervals, in milliseconds, the channel will probe the servers configured in ServerLocators for availability. The default value is 60,000 (60 seconds). See the ProbeServers property for a more detailed description. Although somewhat misnamed, this property defines the Interval between probes, not the actual probing Frequency. The property name is persisted for backward compatibility.



property ProbeFrequency:


ProbeServers

Toggles whether the channel will continuously probe the servers configured in ServerLocators for availability. If enabled (true), the channel will ping all servers at a regular interval to determine if they are reachable. If a server fails to respond, it will be disabled for future calls until a later probe can reach it again. The interval between probes can be configured using the ProbeFrequency property. By default, server probing is turned off.



property ProbeServers:


ServerID

Defines the unique ID of the server to use. This must match the ServerID specified on the TRONamedPipeServer in the server application.



property ServerID: string read write


ServerLocators

Optionally, this collection property can be filled to contain a list of possible servers to be used for fail-over or load balancing purposes. Depending on the settings configured in DispatchOptions, the channel will automatically spread calls over the available servers, or fall back to another server if one fails.



property ServerLocators:


ServerName

Specifies the name of the host running the server. This can be a host name or IP address on the local net, or "." (default), which indicates the local machine.



property ServerName: string read write


SynchronizedProbing

Determines whether server probing happens in the context of the main VCL thread (true, default) or in a background worker thread. See the ProbeServers property for a more detailed description.



property SynchronizedProbing:


TargetUri     (declared in TROTransportChannel)



property TargetUri: TROUri read write


TargetUrl   protected     (declared in TROTransportChannel)



property TargetUrl: string read write


ThreadSafe   protected     (declared in TROTransportChannel)



property ThreadSafe: Boolean read write


Class Methods

ChannelMatchingTargetUri     (declared in TROTransportChannel)



function ChannelMatchingTargetUri(const aUri: TROUri): TROTransportChannel


Parameters:

  • aUri:


ChannelMatchingTargetUrl     (declared in TROTransportChannel)



function ChannelMatchingTargetUrl(const aUrl: string): TROTransportChannel


Parameters:

  • aUrl:


Instance Methods

constructor Create   override

Creates a new instance.


constructor Create(Owner: TComponent)


Parameters:

  • Owner:


destructor Destroy   override

The standard destructor.


destructor Destroy


Assign   override



procedure Assign(aSource: TPersistent)


Parameters:

  • aSource:


AsyncException   protected virtual     (declared in TROTransportChannel)

Notifies about an exception in an asynchronous mode.


procedure AsyncException(aAsyncInterface: IROAsyncInterface; AsyncException: Exception)


Parameters:

  • aAsyncInterface:
  • AsyncException:


BeforeDispatch   protected virtual     (declared in TROTransportChannel)

Allows an implimentation to do necessary preparatory actions (checking the readiness of the channel, restore session data, etc.).


procedure BeforeDispatch(aMessage: IROMessage)


Parameters:

  • aMessage:


ChangeServerLocator   protected virtual     (declared in TROTransportChannel)



procedure ChangeServerLocator(var faultstartlocatoridx: integer; var aRetry: Boolean; const aException: Exception)


Parameters:

  • faultstartlocatoridx:
  • aRetry:
  • aException:


CheckProperties   override



procedure CheckProperties


Connect   virtual



procedure Connect


DataWaiting   protected virtual



function DataWaiting: Boolean


DecodeEventStream   protected     (declared in TROTransportChannel)

Decrypts the stream.


procedure DecodeEventStream(const aStream: TStream)


Parameters:

  • aStream:


Disconnect   virtual



procedure Disconnect


Dispatch (IROMessage)   protected reintroduce overload     (declared in TROTransportChannel)

Sends a request message through the Self channel for processing and gets back an aMessage. CodeGen uses this method when generating a proxy from RODL Files.


procedure Dispatch(aMessage: IROMessage)


Parameters:

  • aMessage:


DoAfterEncryptEvent   protected virtual obsolete     (declared in TROBaseConnection)



procedure DoAfterEncryptEvent(aEncryptedStream: TStream)


Parameters:

  • aEncryptedStream:


DoAfterProbingServerEvent   protected virtual     (declared in TROTransportChannel)

Fires OnAfterProbingServer event


procedure DoAfterProbingServerEvent(const aServerLocator: TROServerLocator; const Failed: Boolean)


Parameters:

  • aServerLocator:
  • Failed:


DoAfterProbingServersEvent   protected virtual     (declared in TROTransportChannel)

Fires OnAfterProbingServers event


procedure DoAfterProbingServersEvent(const ProbedCount: integer; const EnabledCount: integer; const DisabledCount: integer)


Parameters:

  • ProbedCount:
  • EnabledCount:
  • DisabledCount:


DoBeforeDecryptEvent   protected virtual obsolete     (declared in TROBaseConnection)



procedure DoBeforeDecryptEvent(aEncryptedStream: TStream)


Parameters:

  • aEncryptedStream:


DoBeforeProbingServerEvent   protected virtual     (declared in TROTransportChannel)

Fires OnBeforeProbingServer event


procedure DoBeforeProbingServerEvent(const aServerLocator: TROServerLocator)


Parameters:

  • aServerLocator:


DoBeforeProbingServersEvent   protected virtual     (declared in TROTransportChannel)

Fires OnBeforeProbingServers event


procedure DoBeforeProbingServersEvent


DoDecryption   virtual obsolete     (declared in TROBaseConnection)



procedure DoDecryption(iCipherText: TStream; iPlainText: TStream)


Parameters:

  • iCipherText:
  • iPlainText:


DoDecryption2 obsolete     (declared in TROBaseConnection)



procedure DoDecryption2(const iStream: TStream)


Parameters:

  • iStream:


DoEncryption   virtual obsolete     (declared in TROBaseConnection)



procedure DoEncryption(iPlainText: TStream; iCipherText: TStream)


Parameters:

  • iPlainText:
  • iCipherText:


DoEncryption2 obsolete     (declared in TROBaseConnection)



procedure DoEncryption2(const iStream: TStream)


Parameters:

  • iStream:


DoException   protected virtual     (declared in TROTransportChannel)

Fires OnException event


procedure DoException(anException: Exception; var aRetry: Boolean)


Parameters:

  • anException:
  • aRetry:


DoLoginNeeded   protected virtual     (declared in TROTransportChannel)

Fires OnLoginNeeded event


procedure DoLoginNeeded(anException: Exception; var aRetry: Boolean)


Parameters:

  • anException:
  • aRetry:


DoReceiveStreamEvent   protected virtual     (declared in TROTransportChannel)

Fires OnReceiveStream event


procedure DoReceiveStreamEvent(const aStream: TStream)


Parameters:

  • aStream:


DoSendStreamEvent   protected virtual     (declared in TROTransportChannel)

Fires OnSendStream event


procedure DoSendStreamEvent(const aStream: TStream)


Parameters:

  • aStream:


DoServerLocatorAssignmentEvent   protected virtual     (declared in TROTransportChannel)

Fires OnServerLocatorAssignment event


procedure DoServerLocatorAssignmentEvent(const aLocator: TROServerLocator; const aException: Exception)


Parameters:

  • aLocator:
  • aException:


GetPipeName   protected virtual



function GetPipeName: string


GetTransportObject   protected override



function GetTransportObject: TObject


InitServerLocator   protected virtual     (declared in TROTransportChannel)

Sets CurrentLocator


function InitServerLocator: Integer


IntDispatch   protected override



procedure IntDispatch(aRequest: TStream; aResponse: TStream)


Parameters:

  • aRequest:
  • aResponse:


IsEncryptionUsed   protected     (declared in TROTransportChannel)

Specifies current Encryption status


function IsEncryptionUsed: Boolean


Notification   protected override     (declared in TROComponent)

Forwards notification messages to all owned components.


procedure Notification(AComponent: TComponent; Operation: TOperation)


Parameters:

  • AComponent:
  • Operation:


Probe   protected     (declared in TROTransportChannel)

Checks the accessibility of servers from the ServerLocators. This method is intended to provide fail-over and load balancing support in the RemObjects SDK Architecture.


function Probe(aServerLocator: TROServerLocator): boolean


Parameters:

  • aServerLocator:


ProbeAll   protected     (declared in TROTransportChannel)

Checks the availability of all known servers.


procedure ProbeAll


ResetProbingClone   protected virtual     (declared in TROTransportChannel)

Resets channel that is used for probing


procedure ResetProbingClone(aProbe: TROTransportChannel)


Parameters:

  • aProbe:


RetrieveMetadata   protected virtual     (declared in TROTransportChannel)

Retrieves metadata from server


procedure RetrieveMetadata(out Metadata: TStream)


Parameters:

  • Metadata:


RetrieveRODL   protected     (declared in TROTransportChannel)

This method is used for to obtaining the RODL library from the server without havin to rely on a channel-specific mechanism (such as a HTTP request to http://servername:port/rodl).


procedure RetrieveRODL(out RODLLibrary: TRODLLibrary)


Parameters:

  • RODLLibrary:


ROFreeNotification     (declared in TROComponent)

Forwards notification messages to all owned RO components.


procedure ROFreeNotification(AComponent: TComponent)


Parameters:

  • AComponent:


RORemoveFreeNotification     (declared in TROComponent)

Disables destruction notification for specified RO component.


procedure RORemoveFreeNotification(AComponent: TComponent)


Parameters:

  • AComponent:


SendAndRecv   protected virtual



procedure SendAndRecv(aRequest: TStream; aResponse: TStream)


Parameters:

  • aRequest:
  • aResponse:


SendRemoveNotification   protected     (declared in TROComponent)

Sends remove notification to specified component


procedure SendRemoveNotification(AComponent: TComponent)


Parameters:

  • AComponent:


SetServerLocator   protected     (declared in TROTransportChannel)

Retrieves the location details of a server from aServerLocator.


procedure SetServerLocator(aServerLocator: TROServerLocator; anException: Exception)


Parameters:

  • aServerLocator:
  • anException:


TriggerProgress   protected virtual     (declared in TROTransportChannel)

Fires OnProgress event


procedure TriggerProgress(iType: TProgressType; iDirection: TProgressDirection; iTransfered: integer; iTotal: integer)


Parameters:

  • iType:
  • iDirection:
  • iTransfered:
  • iTotal:


Events

onAfterEncrypt obsolete     (declared in TROBaseConnection)



property onAfterEncrypt: TROBaseConnectionOperation read write delegate: procedure Invoke(Sender: TROBaseConnection; aEncryptedStream: TStream)


OnAfterProbingServer     (declared in TROTransportChannel)

Fires after the channel is done probing a specific server for availability. You can use this event to check the result of the probing, possibly to update internal data structures or to display server status in the user interface.



property OnAfterProbingServer: TROEndProbeServerEvent read write delegate: procedure Invoke(Sender: TROTransportChannel; aServerLocator: TROServerLocator; Failed: boolean)


OnAfterProbingServers     (declared in TROTransportChannel)

Fires after the channel is done probing all servers for availability. You can use this event to check the result of the probing, possibly to update internal data structures or to display server status in the user interface.



property OnAfterProbingServers: TROEndProbeServersEvent read write delegate: procedure Invoke(Sender: TROTransportChannel; ProbedCount: integer; EnabledCount: integer; DisabledCount: integer)


OnAsyncException     (declared in TROTransportChannel)

Fires when exception is raised in asynchronous mode



property OnAsyncException: TROAsyncExceptionEvent read write delegate: procedure Invoke(Sender: TROTransportChannel; Async: IROAsyncInterface; anException: Exception)


onBeforeDecrypt obsolete     (declared in TROBaseConnection)



property onBeforeDecrypt: TROBaseConnectionOperation read write delegate: procedure Invoke(Sender: TROBaseConnection; aEncryptedStream: TStream)


OnBeforeProbingServer     (declared in TROTransportChannel)

Fires before the channel starts probing a specific server for availability. You can use this event to:

  • check or adjust the server configuration
  • to include/exclude the server from being probed by changing the TROServerLocator.Enabled property.



property OnBeforeProbingServer: TROBeginProbeServerEvent read write delegate: procedure Invoke(Sender: TROTransportChannel; aServerLocator: TROServerLocator)


OnBeforeProbingServers     (declared in TROTransportChannel)

Fires before the channel starts probing all servers for availability. You can use this event:

  • to check or adjust the server configurations
  • to include/exclude individual server from being probed by changing their TROServerLocator.Enabled properties.



property OnBeforeProbingServers: TROBeginProbeServersEvent read write delegate: procedure Invoke(Sender: TROTransportChannel)


OnException     (declared in TROTransportChannel)

Fires if an exception is raised during the execution of a remote request. This could be an exception returned from the server, a communication problem or an error within the client. Depending on the type of error, your event handler can try to rectify the problem, and set aRetry to true to have the channel try and perform the request again. For example, an application could show a dialog asking the user to confirm if his internet connection is available, with Cancel and Retry buttons. If aRetry is set to true and the call succeeds at the second attempt, the call will return to the original code that initiated the request, as if the exception never happened.



property OnException: TROExceptionEvent read write delegate: procedure Invoke(Sender: TROTransportChannel; anException: Exception; var aRetry: Boolean)


OnLoginNeeded     (declared in TROTransportChannel)

Fires if an EROSessionNotFound (or the descendant SessionNotFoundException) exception is raised during the execution of a remote request. This usually indicates that the server cannot authenticate the client or that the session has expired. The most common use for this event is to perform a call to a special Login service provided by the server (possibly after prompting the user to enter username and password), and to set the aRetry parameter to true if login was successful.



property OnLoginNeeded: TROExceptionEvent read write delegate: procedure Invoke(Sender: TROTransportChannel; anException: Exception; var aRetry: Boolean)


OnProgress     (declared in TROTransportChannel)

This event fires as the channel is transferring data for a request or response to or from the server, informing of the current progress. It can be used to keep the user interface updated during lengthy transfers,e.g. by showing a progress bar or the remaining transfer volume. Note: the accuracy and frequency of calls to OnProgress depends on the channel type; since channels transport data packets in different sized chunks (or even all-at-once), OnProgress might show a very fine progress for some channels, while jumping from 0 to 100% in one step with others.



property OnProgress: TProgressEvent read write delegate: procedure Invoke(iSender: TObject; iType: TProgressType; iDirection: TProgressDirection; iTransferred: integer; iTotal: integer)


OnReceiveStream     (declared in TROTransportChannel)

Fires after a stream with a response message has been received from the server. Use this event handler to inspect and possibly modify the stream, before it continues to be processed by the higher levels of the RemObjects SDK framework.



property OnReceiveStream: TStreamDispatch read write delegate: procedure Invoke(aStream: TStream)


OnSendStream     (declared in TROTransportChannel)

Fires just as a stream with a request message will be sent to the server. The event handler can inspect and possibly modify the stream, before it continues to be sent off to the server.



property OnSendStream: TStreamDispatch read write delegate: procedure Invoke(aStream: TStream)


OnServerLocatorAssignment     (declared in TROTransportChannel)

Fires before changing of a server locator



property OnServerLocatorAssignment: TServerLocatorAssignment read write delegate: procedure Invoke(Sender: TROTransportChannel; aLocator: TROServerLocator; aException: Exception)


See Also


Product: RemObjects SDK
Available Editions: RemObjects SDK for .NET, Xcode, Delphi, Java and JavaScript

Glossary — Articles — Library — Samples

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