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Location:
MTSR.H
Link against: msgs.lib
Link against: msgs_autoshutdown.lib
class CBaseServerMtm : public CActive;
Base class for Server-side MTM components. Server-side MTMs provide all message transport functionality for a particular messaging protocol.
MTM implementers implement a derived class to provide such functionality for their message protocol. Writers of message client applications are never concerned with this class and its sub-classes, as these are only accessed by the Message Server.
Each MTM interprets the generic commands in different ways. For example, a Fax MTM would transmit a fax when asked to copy a fax from a local folder to a fax service. For the same function, an IMAP MTM would create a copy of the message on the remote server and update the message index to show the copy of the message on the remote server. An important initial design task is to the map the functions to the functionality provided by the protocol.
Server-side MTM functions are called by the Message Server as a result of a client request that requires some remote operation with the MTM's protocol. The following steps give a simplified view of the usual sequence of events:
1. the Message Server instantiates a Server-side MTM object through the factory function
2. the Message Server calls the appropriate asynchronous function on the Server-side MTM interface, passing a TRequestStatus argument
3. the Server-side MTM function typically starts whatever asynchronous communications it requires and returns
4. the Server-side MTM is signalled when the asynchronous communications complete, and handles the result
5. the Server-side MTM signals the Message Server, through the TRequestStatus passed earlier
6. the Message Server deletes the Server-side MTM object
To qualify this somewhat:
1. it is up to the Server-side MTM implementation to decide how to translate data back and forth between the formats used by Message Server (index entry, message store, binary files), and that required by the protocol; this is another important design task
2. depending on the protocol being used, the communications sequence can be of considerable complexity; typically it requires division into a number of asynchronous steps
3. for greater efficiency where further commands are shortly expected, deletion of the Server-side MTM object can be prevented
For asynchronous requests, a Server-side MTM should always complete the TRequestStatus with KErrNone. Any errors should be returned in the progress information.
Note the following significant groups of functions:
1. Copy and move from remote functions: CopyToLocalL() and MoveToLocalL() are called by the Message Server to get a selection of entries from a remote location. For many protocols, this should be
interpreted as message retrieval. For protocols where messages exist on a remote server, this function is typically used to
download specific messages, after an initial connection has downloaded message headers.
2. Copy and move to remote functions: CopyFromLocalL() and MoveFromLocalL() are called by the Message Server to copy/move a selection of entries to a remote location. For many protocols, this should
be interpreted as message sending.
3. Copy and move within remote functions: CopyWithinServiceL() and MoveWithinServiceL() are called by the Message Server to copy a selection of entries within a remote service. An example of their use might be
for a user rearranging messages within remote folders.
CBase - Base class for all classes to be instantiated on the heap
CActive - The core class of the active object abstraction
CBaseServerMtm - Base class for Server-side MTM components
Defined in CBaseServerMtm:
CBaseServerMtm(), ChangeL(), CommandExpected(), CopyFromLocalL(), CopyToLocalL(), CopyWithinServiceL(), CreateL(), DeleteAllL(), DoComplete(), DoRunL(), Extension_(), GetInterface(), MoveFromLocalL(), MoveToLocalL(), MoveWithinServiceL(), Progress(), RunError(), RunL(), StartCommandL(), SystemProgress(), iServerEntry, ~CBaseServerMtm()
Inherited from CActive:
Cancel(),
Deque(),
DoCancel(),
EPriorityHigh,
EPriorityIdle,
EPriorityLow,
EPriorityStandard,
EPriorityUserInput,
IsActive(),
IsAdded(),
Priority(),
SetActive(),
SetPriority(),
TPriority,
iStatus
Inherited from CBase:
Delete(),
operator new()
IMPORT_C ~CBaseServerMtm();
Destructor.
This cleans up the base class. CBaseServerMtm-derived objects are deleted by the Message Server when they are no longer required.
Derived classes can implement a destructor to do any additional clean up tasks that they require.
protected: IMPORT_C CBaseServerMtm(CRegisteredMtmDll &aRegisteredMtmDll, CMsvServerEntry *aServerEntry);
Constructor.
The function is passed a CMsvServerEntry object in aServerEntry. This object is used to access and change Message Server entries. Its context is initially set either
to the parent of the entry or selection being operated on, or the entry itself. The constructor stores it in the protected
iServerEntry member.
Derived classes can implement a constructor to perform any additional MTM-specific setup that can be safely carried out in a constructor. Such constructors must call the base class constructor function.
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virtual void CopyToLocalL(const CMsvEntrySelection &aSelection, TMsvId aDestination, TRequestStatus &aStatus)=0;
Copies a selection of entries from a remote location to a local location. This will only be meaningful for some protocols.
Requirements:
Implementations should provide this function if the messaging protocol supports retrieval of remote entries. If this is not supported, implementations should leave with KErrNotSupported.
Implementations of this function have three fundamental steps:
1. doing the transfer operation using the appropriate communications protocols
2. converting protocol-specific data into the three-part storage format (index entry, message store, binary files) required by the Message Server
3. updating entries in the Message Server
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virtual void CopyFromLocalL(const CMsvEntrySelection &aSelection, TMsvId aDestination, TRequestStatus &aStatus)=0;
Copies a selection of entries from a local location to a remote location.
Requirements:
Implementations should provide this function if the messaging protocol supports retrieval of remote entries. If this is not supported, implementations should leave with KErrNotSupported.
Implementations of this function have three fundamental steps:
1. reading entry data
2. converting entry data from the Message Server format into that required by the protocol
3. doing the transfer operation using the appropriate communications protocols
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virtual void CopyWithinServiceL(const CMsvEntrySelection &aSelection, TMsvId aDestination, TRequestStatus &aStatus)=0;
Copies a selection of entries within a remote location.
Requirements:
Implementations should provide this function if the messaging protocol supports the ability to copy entries within a remote service. If this is not supported, implementations should leave with KErrNotSupported.
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virtual void DeleteAllL(const CMsvEntrySelection &aSelection, TRequestStatus &aStatus)=0;
Deletes each entry in the supplied selection when called by the message Server. If any of the entries in the selection is a parent entry, then all its children should also be deleted, recursively to the bottom of the ownership tree.
Implementations should provide this function if the messaging protocol supports deletion of remote entries. If this is not supported, implementations should leave with KErrNotSupported.
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virtual void CreateL(TMsvEntry aNewEntry, TRequestStatus &aStatus)=0;
Creates a new remote entry with relevant data when called by the Message Server.
Implementations should provide this function if the messaging protocol supports creation of remote entries. If this is not supported, implementations should leave with KErrNotSupported.
As with ChangeL(), the Server-side MTM implementation must decide what information in the TMsvEntry is relevant to the remote entry, and translate it appropriately for the specific protocol. Most of the data contained in
the TMsvEntry is specific to the Message Server, and would probably have no direct correlation with the protocol's own storage format.
For example, for a folder, probably only the name and parent are needed, so if the protocol supports creation of remote folders,
the implementation could:
1. check for a folder type entry
2. get the folder name and parent details from aNewEntry
3. initiate a protocol-specific action to create the remote folder
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virtual void ChangeL(TMsvEntry aNewEntry, TRequestStatus &aStatus)=0;
Updates a remote entry with relevant data when called by the Message Server.
Implementations should provide this function if the messaging protocol supports updating of remote entries. If this is not supported, implementations should leave with KErrNotSupported.
The Server-side MTM implementation must decide what information in the TMsvEntry is relevant to the remote entry, and translate it appropriately for the specific protocol. Most of the data contained in
the TMsvEntry is specific to the Symbian OS Message Server, and would probably have no direct correlation with the protocol's own storage
format. Some entry data may however be useful. For example, if the protocol supports remote renaming of folders, the implementation
could:
1. check for a folder type entry
2. extract the folder name from aNewEntry.iDetails
3. check if the folder name has changed by comparing the new name with iDetails in the index entry currently; if not, complete with KErrNone
4. initiate a protocol-specific action to rename the remote folder
The implementation should also always update the local Message Server index through CMsvServerEntry::ChangeL().
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virtual void StartCommandL(CMsvEntrySelection &aSelection, TInt aCommand, const TDesC8 &aParameter, TRequestStatus &aStatus)=0;
Executes an MTM-specific operation on a selection of entries when called by the Message Server.
The call is made as a response to a client program invoking an MTM-specific operation through CBaseMtm::InvokeSyncFunctionL()/InvokeAsyncFunctionL(). The aSelection, aCommand, and aParameter arguments pass the values of the original aSelection, aFunctionId,
and aParameter respectively arguments from such a call. The use (if any) of the aSelection and aParameter arguments by the
function depends on the command.
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virtual TBool CommandExpected()=0;
Tests if the Server-side MTM object should be deleted when called by the Message Server
It is useful to stop the MTM being deleted when more commands are expected shortly. This would be the case, for example, after receiving a command to go online.
If there are no more commands expected by the Server-side MTM object, then the function should return EFalse, and the Message Server will delete it.
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virtual const TDesC8 &Progress()=0;
This function is called by the Message Server to get progress information for the current asynchronous operation.
The call is made as a response to a client program requesting progress information through CMsvOperation::ProgressL(). The packing format used in the TDesC8 is MTM-specific. Only the implementation of the User Interface MTM progress information functions need to understand the format.
The progress buffer should have a maximum size of 256 bytes.
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virtual void MoveToLocalL(const CMsvEntrySelection &aSelection, TMsvId aDestination, TRequestStatus &aStatus)=0;
Moves a selection of entries from a remote location to a local location.
Requirements:
Implementations should provide this function if the messaging protocol supports retrieval of remote entries. If this is not supported, implementations should leave with KErrNotSupported.
Implementations of this function have three fundamental steps:
1. doing the transfer operation using the appropriate communications protocols
2. converting protocol-specific data into the three-part storage format (index entry, message store, binary files) required by the Message Server
3. updating entries in the Message Server
MoveToLocalL() should differ from CopyToLocalL() in additionally deleting the original remote data.
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virtual void MoveFromLocalL(const CMsvEntrySelection &aSelection, TMsvId aDestination, TRequestStatus &aStatus)=0;
Moves a selection of entries from a local location to a remote location.
Requirements:
Implementations should provide this function if the messaging protocol supports retrieval of remote entries. If this is not supported, implementations should leave with KErrNotSupported.
Implementations of this function have three fundamental steps:
1. reading entry data
2. converting entry data from the Message Server format into that required by the protocol
3. doing the transfer operation using the appropriate communications protocols
The implementation of MoveFromLocalL() should differ from CopyFromLocalL() in additionally deleting the original local data.
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virtual void MoveWithinServiceL(const CMsvEntrySelection &aSelection, TMsvId aDestination, TRequestStatus &aStatus)=0;
Moves a selection of entries within a remote location.
Requirements:
Implementations should provide this function if the messaging protocol supports the ability to move entries within a remote service. If this is not supported, implementations should leave with KErrNotSupported.
The implementation of MoveWithinServiceL() should differ from CopyWithinServiceL() in additionally deleting the original data.
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IMPORT_C TInt SystemProgress(TMsvSystemProgress &aOutSysProg);
This call leads to calling one of the server Mtms to populate the TMsvSystemProgress structure.
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protected: virtual void DoRunL()=0;
Handles the completion of any asynchronous requests that it makes. It is called from the base class RunL() .
Note that any leaves made by this function result in DoComplete() being called with the leave code.
protected: virtual void DoComplete(TInt aError)=0;
Called by the base class RunL() if DoRunL() leaves.
It should be implemented to handle this error. For example, progress information could be updated to reflect the problem.
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protected: virtual IMPORT_C TInt Extension_(TUint aExtensionId, TAny *&a0, TAny *a1);
The extension method provides a polymorphic behaviour to call the correct SystemProgress function.
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private: virtual IMPORT_C void RunL();
Provides a simple implementation of CActive::RunL() that calls the derived class's DoRunL() function. If that function leaves, then the leave is trapped, and DoComplete() is called to handle the error.
This implementation ensures that derived classes handle leave errors in RunL(), rather than the default of the error being passed to the active scheduler.
private: virtual IMPORT_C TInt RunError(TInt aError);
Handles the cases where RunL is leaving.
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protected: virtual IMPORT_C TAny *GetInterface(TUid aUid);
Returns a pointer to the interface with the specified Uid.
This method is the first part of an extension pattern to allow for more functionality to be supported without adding virtual methods to this base class.
The default implementation returns a NULL pointer.
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protected: CMsvServerEntry * iServerEntry;
The entry on which to operate. It is set in the constructor.
The destructor deletes this member.
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Copyright ©2008 Symbian Software Ltd. |
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