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This document is the guide for pvDatabaseCPP, which is one of the components of EPICS-7
Doxgen for pvDatabase is located at: doxygen .
pvDatabase is a framework for implementing a network accessible database of smart memory resident records.
This document is intended for anyone creating new PVRecords. pvService Describes a good way to create services via PVRecords.
pvDatabase has the following components:
This is the code for creating a PVDatabase, which is a database of PVRecords.
A PVRecord consists of a PVStructure and a set of methods for accessing the record. The PVStructure has the data for the record. There is a base class that implements all the methods associated with accessing the record. But some are virtual and can be implemented by a derived class.
The virtual methods are:
ChannelProviderLocal, described below, allows client to access a record via the network. But another record in the same ioc can access the record via the PVDatabase. For example if the other record wants to put data into the record it must do something like the following:
PVRecordPtr pvr(pvRecord.lock());
if(!pvr) throw std::logic_error("pvRecord is deleted");
try {
{
epicsGuard<PVRecord> guard(*pvr);
pvr->beginGroupPut();
// put data
pvr->process();
pvr->endGroupPut();
}
} catch(std::exception& ex) {
// handle error
}
The following are virtual methods.
init Initialization method.
start Called before a record is added to database.
process Process the record.
remove Remove the PVRecord.
getService Return a service corresponding to the specified request PVStructure.
The following are implemented by the base class.
create Create a soft record.
getRecordName Get the record name.
getPVStructure Get the PVStructure for the record.
getPVRecordStructure Get the PVRecordStrucure.
findPVRecordField Find a PVRecordField
lock Lock the record. No other code can access the record until unlock
unlock Unlock the record.
tryLock Try to lock the record.
lockOtherRecord Client holding lock can lock one other record.
addPVRecordClient Every client that accesses the record can call this
so that the client can be notified when the record is deleted.
addListener This must be called before calling pvRecordField.addListener.
nextMasterPVField PVCopyTraverseMasterCallback method.
removeListener Remove a listener.
beginGroupPut Begins a group of puts.
endGroupPut Ends a group of puts.
getTraceLevel Get trace level (0,1,2) means (nothing,lifetime,process)
setTraceLevel Set trace level (0,1,2) means (nothing,lifetime,process)
getAsLevel Get the AS level.
getAsGroup Get the AS group name.
setAsLevel Set access security level.
setAsGroup Set access security group.
PVRecordStructure has methods:
getPVRecordFields Get the sub fields. getPVStructure Get the PVStructure.
PVRecordField has methods:
getParent Get the PVRecordStructure.
getPVField Get the PVField.
getFullFieldName Get the full field name.
getFullName Get the recordName plus the full name of the field.
getPVRecord Get the PVRecord to which this field belongs.
postPut This is called by the code that implements the data interface.
It is called whenever the put method is called.
PVRecordClient has methods:
detach Detach from the record because it is being removed.
PVListener has methods:
dataPut This is called if the listener has called PVRecordField::addListener for pvRecordField. beginGroupPut Begin a set of puts. endGroupPut End a set of puts. unlisten Connection to record is being terminated.
PVDatabase has methods:
findRecord Find a record in the database. addRecord Add a record to the database. removeRecord Remove a record from the database. getRecordNames Get the names of all the records in the database. getMaster Get the master database. This is what clients access.
This code provides the ability for a pvAccess client to communicate with PVRecords. qsrv is the server side of pvAccess that provides access to an IOC.
The pvAccess component of pvDatabase implements a provider named local and registers it with qsrv
ChannelProviderLocal has methods:
initAs Initialize access security configuration. isAsActive Is access security active. getProviderName Returns the channel provider name. channelFind Returns either a null channelFind or a channelFind for records in the PVDatabase. channelList Provide the caller with a list of the record names on the PVDatabase. createChannel Create a channel for a record. getTraceLevel Get trace level (0,1,2) means (nothing,lifetime,process) setTraceLevel Set trace level (0,1,2) means (nothing,lifetime,process) getChannelProvider Get the channel provider.
ChannelLocal has methods:
detach This is called when a record is being removed from the database,
getRequesterName Get the requester name.
message Passes the message to the channel requester.
getProvider Get the channel provider.
getRemoteAddress Get the remote address.
getConnectionState Get the connection state.
getChannelName Get the channel name.
getChannelRequester Get the channel requester.
isConnected Is the channel connected?
getField Get the introspection interface for a subField.
getAccessRights Get the access rights for the record.
createChannelProcess Create a channelProcess.
createChannelGet Create a channelGet.
createChannelPut Create a channelPut.
createChannelPutGet Create a channelPutGet.
createChannelRPC Create a channelRPC
The PVRecord must implement getService or an empty shared pointer is returned.
createMonitor Create a Monitor
createChannelArray Create a channelArray.
printInfo Displays a message.
canWrite Can the client write to the record.
canRead Can the client read from the record.
PVPlugin has methods:
create Creates a plugin filter
PVPluginRegistry has methods:
registerPlugin Register a plugin. find Find a plugin.
PVFilter has methods:
filter Update copy or master getName Get the filter name.
PVArrayPlugin has methods:
create Create a PVArrayFilter
PVArrayFilter has methods:
create Create an array filter filter Perform a filter operation. getName Get the filter name.
PVDeadbandPlugin has methods:
create Create a PVDeadbandFilter
PVDeadbandFilter has methods:
create Create a deadband filter filter Perform a filter operation. getName Get the filter name.
PVTimestampPlugin has methods:
create A plugin for a filter that sets a timeStamp to the current time
PVTimestampFilter has methods:
create Create a timeStamp filter filter Perform a filter operation. getName Get the filter name.