TROTransportChannel

 

Standard component constructor

constructor Create(aOwner: TComponent)

Parameters:

• aOwner: Owner

---

Copies the contents of another, similar object.

procedure Assign(Source: TPersistent)

Parameters:

• Source: Instance whose properties will be copied

---

Copies the events of another, similar object.

procedure AssignEvents(aSource: TROTransportChannel)

Parameters:

• aSource: Instance whose properties will be copied

---

Copies the specific properties of another, similar object.

procedure AssignSpecificProperties(aSource: TROTransportChannel)

Parameters:

• aSource: Instance whose properties will be copied

---

Notifies about an exception in an asynchronous mode.

procedure AsyncException(aAsyncInterface: IROAsyncInterface; AsyncException: Exception)

Parameters:

• aAsyncInterface: Exception source
• AsyncException: Exception data

---

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

procedure BeforeDispatch(aMessage: IROMessage)

Parameters:

• aMessage: Message

---

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

---

procedure ChangeServerLocator(var aFaultStartLocatorIdx: Integer; var aRetry: Boolean; const aException: Exception)

Parameters:

• aFaultStartLocatorIdx:
• aRetry:
• aException:

---

Creates a client channel instance with type, target host and target port matching the provided target Uri.
F.e. for provided uri supertcp://192.168.1.100:7020/bin this method will return an instance of the Super Tcp channel with target host set to 192.168.1.100 and port set to 7020.

class function ChannelMatchingTargetUri(const aUri: TROUri): TROTransportChannel

Parameters:

• aUri: Server Uri

---

class function ChannelMatchingTargetUrl(const aUrl: string): TROTransportChannel

Parameters:

• aUrl:

---

Validates channel properties

procedure CheckProperties

---

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

---

Decrypt stream

procedure DecryptStream(const Source: TStream; const Dest: TStream)

Parameters:

• Source: Source
• Dest: Destination

---

Decrypt stream

procedure DecryptStream(const Stream: TStream)

Parameters:

• Stream: Stream

---

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: (In/out) message data

---

Configures the available fail-over and load balancing options provided by the Remoting 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: TRODispatchOptions read write

---

Fires OnAfterProbingServer event

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

Parameters:

• aServerLocator: Server locator
• aFailed:

---

Fires OnAfterProbingServer event

procedure DoAfterProbingServersEvent(const aProbedCount: Integer; const aEnabledCount: Integer; const aDisabledCount: Integer)

Parameters:

• aProbedCount:
• aEnabledCount:
• aDisabledCount:

---

procedure DoBeforeDecryptEvent(aEncryptedStream: TStream)

Parameters:

• aEncryptedStream: Stream

---

Fires OnBeforeProbingServer event

procedure DoBeforeProbingServerEvent(const aServerLocator: TROServerLocator)

Parameters:

• aServerLocator: Server locator

---

Fires OnBeforeProbingServers event

procedure DoBeforeProbingServersEvent

---

Detects SSL state

function DoNeedSSL: Boolean

---

Fires OnSendStream event

procedure DoReceiveStreamEvent(const Dest: TStream)

Parameters:

• Dest: Stream

---

Fires OnSendStream event

procedure DoSendStreamEvent(const Source: TStream)

Parameters:

• Source: Stream

---

Fires OnServerLocatorAssignment event

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

Parameters:

• aLocator:
• aException:

---

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

---

Encrypt stream

procedure EncryptStream(const Source: TStream; const Dest: TStream)

Parameters:

• Source: Source
• Dest: Destination

---

Encrypt stream

procedure EncryptStream(const Stream: TStream)

Parameters:

• Stream: Stream

---

property FaultToleranceLocatorIdx: Integer read write

---

Returns current channel state

function GetBusy: Boolean

---

function GetChannelFromPool: TROTransportChannel

---

Returns itself.

function GetTransportObject: TObject

---

Sets CurrentLocator

function InitServerLocator: Integer

---

Checks if encryption was used

function IsEncryptionUsed: Boolean

---

property IsProbeMode: Boolean read

---

Checks state of stream

function IsStreamEncrypted(Source: TStream): Boolean

Parameters:

• Source: Stream

---

procedure LaunchAsyncTask(aRequest: IROAsyncRequest)

Parameters:

• aRequest:

---

property LoadBalancerLocatorIdx: Integer read write

---

Loads SSL library if SSL protocol is used

procedure LoadSSL

---

Forwards notification messages to all owned components.

procedure Notification(AComponent: TComponent; Operation: TOperation)

Parameters:

• AComponent: component
• Operation: operation

---

Fired after stream was encrypted

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

---

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 OnAfterProbingServer(Sender: TROTransportChannel; aServerLocator: TROServerLocator; Failed: Boolean)

---

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 OnAfterProbingServers(Sender: TROTransportChannel; ProbedCount: Integer; EnabledCount: Integer; DisabledCount: Integer)

---

Fires when exception is raised in asynchronous mode

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

---

Fired before stream will be decrypted

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

---

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 property.

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

---

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 properties.

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

---

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 OnLoginNeeded(Sender: TROTransportChannel; anException: Exception; var aRetry: Boolean)

---

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 OnProgress(aSender: TObject; aType: TProgressType; aDirection: TProgressDirection; aTransferred: Integer; aTotal: Integer)

---

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 Remoting SDK framework.

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

---

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 OnSendStream(aStream: TStream)

---

Fires before changing of a server locator.

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

---

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

function Probe(aServerLocator: TROServerLocator): Boolean

Parameters:

• aServerLocator: Server locator

---

Checks the availability of all known servers.

procedure ProbeAll

---

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: Cardinal read write

---

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: Boolean read write

---

Resets channel that is used for probing

procedure ResetProbingClone(aProbe: TROTransportChannel)

Parameters:

• aProbe: Probing clone

---

Returns server-side RODL.

procedure RetrieveMetadata(out Dest: TStream)

Parameters:

• Dest: Stream

---

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: Result

---

procedure ReturnChannelToPool(aChannel: TROTransportChannel)

Parameters:

• aChannel:

---

Forwards notification messages to all owned components.

procedure ROFreeNotification(aComponent: TComponent)

Parameters:

• aComponent: component

---

Forwards notification messages to all owned components.

procedure RORemoveFreeNotification(aComponent: TComponent)

Parameters:

• aComponent: component

---

Forwards notification messages to all owned components.

procedure SendRemoveNotification(aComponent: TComponent)

Parameters:

• aComponent: component

---

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: TROServerLocatorCollection read write

---

procedure SetAsyncBusy(const Value: Boolean)

Parameters:

• Value:

---

Retrieves the location details of a server from aServerLocator.

procedure SetServerLocator(aServerLocator: TROServerLocator; anException: Exception)

Parameters:

• aServerLocator: Configuration data of the server
• anException: Exception

---

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: Boolean read write

---

Target URI

property TargetUri: TROUri read write

---

The address of the server.

property TargetUrl: string read write

---

property ThreadSafe: Boolean read write

---

Fires OnProgress event

procedure TriggerProgress(aType: TProgressType; aDirection: TProgressDirection; aTransfered: Integer; aTotal: Integer)

Parameters:

• aType: progress type
• aDirection: direction
• aTransfered: transfered bytes
• aTotal: total bytes

 

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

---

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

---

Configures the available fail-over and load balancing options provided by the Remoting 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: TRODispatchOptions read write

---

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

---

property FaultToleranceLocatorIdx: Integer read write

---

property IsProbeMode: Boolean read

---

property LoadBalancerLocatorIdx: Integer read write

---

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: Cardinal read write

---

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: Boolean read write

---

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: TROServerLocatorCollection read write

---

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: Boolean read write

---

Target URI

property TargetUri: TROUri read write

---

The address of the server.

property TargetUrl: string read write

---

property ThreadSafe: Boolean read write

 

Creates a client channel instance with type, target host and target port matching the provided target Uri.
F.e. for provided uri supertcp://192.168.1.100:7020/bin this method will return an instance of the Super Tcp channel with target host set to 192.168.1.100 and port set to 7020.

class function ChannelMatchingTargetUri(const aUri: TROUri): TROTransportChannel

Parameters:

• aUri: Server Uri

---

class function ChannelMatchingTargetUrl(const aUrl: string): TROTransportChannel

Parameters:

• aUrl:

 

Standard component constructor

constructor Create(aOwner: TComponent)

Parameters:

• aOwner: Owner

---

Copies the contents of another, similar object.

procedure Assign(Source: TPersistent)

Parameters:

• Source: Instance whose properties will be copied

---

Copies the events of another, similar object.

procedure AssignEvents(aSource: TROTransportChannel)

Parameters:

• aSource: Instance whose properties will be copied

---

Copies the specific properties of another, similar object.

procedure AssignSpecificProperties(aSource: TROTransportChannel)

Parameters:

• aSource: Instance whose properties will be copied

---

Notifies about an exception in an asynchronous mode.

procedure AsyncException(aAsyncInterface: IROAsyncInterface; AsyncException: Exception)

Parameters:

• aAsyncInterface: Exception source
• AsyncException: Exception data

---

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

procedure BeforeDispatch(aMessage: IROMessage)

Parameters:

• aMessage: Message

---

procedure ChangeServerLocator(var aFaultStartLocatorIdx: Integer; var aRetry: Boolean; const aException: Exception)

Parameters:

• aFaultStartLocatorIdx:
• aRetry:
• aException:

---

Validates channel properties

procedure CheckProperties

---

Decrypt stream

procedure DecryptStream(const Source: TStream; const Dest: TStream)

Parameters:

• Source: Source
• Dest: Destination

---

Decrypt stream

procedure DecryptStream(const Stream: TStream)

Parameters:

• Stream: Stream

---

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: (In/out) message data

---

Fires OnAfterProbingServer event

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

Parameters:

• aServerLocator: Server locator
• aFailed:

---

Fires OnAfterProbingServer event

procedure DoAfterProbingServersEvent(const aProbedCount: Integer; const aEnabledCount: Integer; const aDisabledCount: Integer)

Parameters:

• aProbedCount:
• aEnabledCount:
• aDisabledCount:

---

procedure DoBeforeDecryptEvent(aEncryptedStream: TStream)

Parameters:

• aEncryptedStream: Stream

---

Fires OnBeforeProbingServer event

procedure DoBeforeProbingServerEvent(const aServerLocator: TROServerLocator)

Parameters:

• aServerLocator: Server locator

---

Fires OnBeforeProbingServers event

procedure DoBeforeProbingServersEvent

---

Detects SSL state

function DoNeedSSL: Boolean

---

Fires OnSendStream event

procedure DoReceiveStreamEvent(const Dest: TStream)

Parameters:

• Dest: Stream

---

Fires OnSendStream event

procedure DoSendStreamEvent(const Source: TStream)

Parameters:

• Source: Stream

---

Fires OnServerLocatorAssignment event

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

Parameters:

• aLocator:
• aException:

---

Encrypt stream

procedure EncryptStream(const Source: TStream; const Dest: TStream)

Parameters:

• Source: Source
• Dest: Destination

---

Encrypt stream

procedure EncryptStream(const Stream: TStream)

Parameters:

• Stream: Stream

---

Returns current channel state

function GetBusy: Boolean

---

function GetChannelFromPool: TROTransportChannel

---

Returns itself.

function GetTransportObject: TObject

---

Sets CurrentLocator

function InitServerLocator: Integer

---

Checks if encryption was used

function IsEncryptionUsed: Boolean

---

Checks state of stream

function IsStreamEncrypted(Source: TStream): Boolean

Parameters:

• Source: Stream

---

procedure LaunchAsyncTask(aRequest: IROAsyncRequest)

Parameters:

• aRequest:

---

Loads SSL library if SSL protocol is used

procedure LoadSSL

---

Forwards notification messages to all owned components.

procedure Notification(AComponent: TComponent; Operation: TOperation)

Parameters:

• AComponent: component
• Operation: operation

---

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

function Probe(aServerLocator: TROServerLocator): Boolean

Parameters:

• aServerLocator: Server locator

---

Checks the availability of all known servers.

procedure ProbeAll

---

Resets channel that is used for probing

procedure ResetProbingClone(aProbe: TROTransportChannel)

Parameters:

• aProbe: Probing clone

---

Returns server-side RODL.

procedure RetrieveMetadata(out Dest: TStream)

Parameters:

• Dest: Stream

---

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: Result

---

procedure ReturnChannelToPool(aChannel: TROTransportChannel)

Parameters:

• aChannel:

---

Forwards notification messages to all owned components.

procedure ROFreeNotification(aComponent: TComponent)

Parameters:

• aComponent: component

---

Forwards notification messages to all owned components.

procedure RORemoveFreeNotification(aComponent: TComponent)

Parameters:

• aComponent: component

---

Forwards notification messages to all owned components.

procedure SendRemoveNotification(aComponent: TComponent)

Parameters:

• aComponent: component

---

procedure SetAsyncBusy(const Value: Boolean)

Parameters:

• Value:

---

Retrieves the location details of a server from aServerLocator.

procedure SetServerLocator(aServerLocator: TROServerLocator; anException: Exception)

Parameters:

• aServerLocator: Configuration data of the server
• anException: Exception

---

Fires OnProgress event

procedure TriggerProgress(aType: TProgressType; aDirection: TProgressDirection; aTransfered: Integer; aTotal: Integer)

Parameters:

• aType: progress type
• aDirection: direction
• aTransfered: transfered bytes
• aTotal: total bytes

 

Fired after stream was encrypted

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

---

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 OnAfterProbingServer(Sender: TROTransportChannel; aServerLocator: TROServerLocator; Failed: Boolean)

---

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 OnAfterProbingServers(Sender: TROTransportChannel; ProbedCount: Integer; EnabledCount: Integer; DisabledCount: Integer)

---

Fires when exception is raised in asynchronous mode

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

---

Fired before stream will be decrypted

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

---

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 property.

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

---

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 properties.

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

---

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 OnLoginNeeded(Sender: TROTransportChannel; anException: Exception; var aRetry: Boolean)

---

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 OnProgress(aSender: TObject; aType: TProgressType; aDirection: TProgressDirection; aTransferred: Integer; aTotal: Integer)

---

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 Remoting SDK framework.

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

---

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 OnSendStream(aStream: TStream)

---

Fires before changing of a server locator.

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