Package org.diirt.datasource

See: Description

Interface Summary

Interface	Description
ChannelWriteCallback	Called by the ChannelHandler once a write is completed.
Collector<I,O>	A collector can be written from one thread and read from another and provides the point where two subsystems and their rate can be decoupled.
DataSourceTypeAdapter<ConnectionPayload,MessagePayload>	Matches and fills a cache with the data from connection and message payloads.
DataSourceTypeAdapterSet	A set of type adapters.
ExpressionLanguage.OneArgFunction<R,A>	A user provided single argument function.
ExpressionLanguage.TwoArgFunction<R,A1,A2>	A user provided double argument function.
PVReader<T>	An object representing the PVReader.
PVReaderListener<T>	Callback for any change in the PV value.
PVWriter<T>	An object representing a writable PV.
PVWriterListener<T>	Callback for delivery notification of new value.
ReadFunction<R>	A basic building block in the PVManager framework that can return a result of a given type.
ValueCache<T>	Represent a building block that can store a particular value
WriteFunction<A>	A basic building block in the PVManager framework that can write an object of a given type.

Class Summary

Class	Description
Aggregator<R,A>	Aggregates the data out of a Collector into a new data type.
BasicTypeSupport	Implements support for basic standard java types.
CacheCollector<T>	Collects value at read rate and keeps the last n.
ChannelHandler	Manages the connection for each channel of a data source.
ChannelHandlerReadSubscription	Groups all the parameters required to add a reader to a ChannelHandler.
ChannelHandlerWriteSubscription	Groups all the parameters required to add a writer to a ChannelHandler.
ChannelReadRecipe	The recipe for the read connection to a single channel.
ChannelWriteRecipe	The recipe for the write connection to a single channel.
CompositeDataSource	A data source that can dispatch a request to multiple different data sources.
CompositeDataSourceConfiguration	Configuration for CompositeDataSource.
ConfigurableDataSourceProvider<D extends DataSource,C extends DataSourceConfiguration<D>>	DataSourceProvider for a data source that require configuration.
ConnectionCollector	A specialized collector to handle multiple channels that can be added/removed dynamically and which gets translated to a single connection flag for a reader or writer.
DataSource	A source for data that is going to be processed by the PVManager.
DataSourceConfiguration<T extends DataSource>	The configuration for a data source.
DataSourceProvider	A class that provides support for a DataSource.
DataSourceTypeSupport	The type support for a datasource.
ExceptionHandler	This class receives all the exceptions generated by a PV.
ExpressionLanguage	Operators to constructs expression of PVs that the PVManager will be able to monitor.
ExpressionLanguage.Filter<T>	Filters a data stream, removing updates that match the given function.
ForwardCache<T,R>	A cache that, after a value is put in the given value cache, calculates the value of the forward function and stores it in the forward writer, while locking on the forward function.
LatestValueCollector<T>	A collector that keeps only the latest value.
MultiplexedChannelHandler<ConnectionPayload,MessagePayload>	Implements a ChannelHandler on top of a single subscription and multiplexes all reads on top of it.
Notification<T>	Used by NotificationSupport to communicate whether a new notification is needed, and what should be the type to be notified.
NotificationSupport<T>	Dedicated notification type support.
PV<R,W>	A PV that can be both read and written.
PVConfiguration<R,W>	Allows to configure the type of read/write PV to create.
PVDirector<T>	Orchestrates the different elements of pvmanager to make a reader functional.
PVManager	Entry point for the library, manages the defaults and allows to create PVReader, PVWriter and PV from an read or write expression.
PVReaderConfiguration<T>	An expression used to set the final parameters on how the pv expression should be read.
PVReaderEvent<T>	An event for the reader.
PVWriterConfiguration<T>	An expression used to set the final parameters on how the pv expression should be written.
PVWriterDirector<T>	Orchestrates the different elements of pvmanager to make a writer functional.
PVWriterEvent<T>	An event for the writer.
QueueCollector<T>	Collects value at read rate and puts them in a queue.
ReadExpressionTester
ReadRecipe	Represents all the information necessary to connect to a DataSource.
ReadRecipeBuilder	Builder class for ReadRecipe.
TypeSupport<T>	Implements the mechanism for registering different types so that the library knows how to handle them.
ValueCacheImpl<T>	Represent a building block that can store a particular value
WriteCache<T>	Represent part of the write recipe that holds the value for one pv.
WriteExpressionTester
WriteRecipe	Represents all the values, channel names and ordering information needed for writing
WriteRecipeBuilder	A builder for WriteRecipe.

Exception Summary

Exception	Description
TimeoutException	Exception thrown when a PVReader or PVWriter exceed their timeout.

Package org.diirt.datasource Description

Examples

You can find examples in link org.diirt.datasource.sample package. We stopped including examples in the documentation itself because they tend to become stale. We link to actual code that is part of the build, so that there is more of a guarantee that they stay correct

1. Configuration examples - how to configure pvmanager to read from the right datasource and dispatch events on the right thread.
2. Basic examples - how to read/write from a single channel.
3. Multiple channel examples - how to read/write multiple channels at a time.
4. VType examples - how to work with actual type and how to aggregate them in bigger structures.

Package description

This package contains all the basic components of the PVManager framework and the basic support for the language to define the creation.

There are two distinct parts in the PVManager framework. The first part includes all the elements that deal with data directly: read from various sources (DataSource), performing computation (ReadFunction), collecting data (Collector), scanning at the UI rate (PVDirector) and notify on appropriate threads.

The second part consists of an expression language that allows to define how to connect the first set of objects with each other. SourceRateExpression describes data as it's coming out at the network rate, DesiredRateExpression defines data at the scanning rate for the UI, and ExpressionLanguage defines static methods that define the operator in the expression language.

Users can extend both the first part (by extending support for different types, providing different support for different data source or creating new computation elements) and the second part (by extending the language to support other cases. All support for data types is relegated to separate packages: you can use the same style to extend the framework to your needs.