IndexedEvent (dxFeed API 3.319)

Type Parameters:

T - type of the event symbol for this event type.

All Superinterfaces:

EventType<T>, Serializable

All Known Subinterfaces:

TimeSeriesEvent<T>

All Known Implementing Classes:

AnalyticOrder, Candle, DailyCandle, Greeks, OptionSale, Order, OrderBase, Series, SpreadOrder, TheoPrice, TimeAndSale, Underlying
```
public interface IndexedEvent<T>
extends EventType<T>
```
Represents an indexed collection of up-to-date information about some condition or state of an external entity that updates in real-time. For example, Order represents an order to buy or to sell some market instrument that is currently active on a market exchange and multiple orders are active for each symbol at any given moment in time. Candle represent snapshots of aggregate information about trading over a specific time period and there are multiple periods available. The Candle is also an example of TimeSeriesEvent that is a more specific event type.
Index for each event is available via index property. Indexed events retain information about multiple events per symbol based on the event index and are conflated based on the event index. Last indexed event for each symbol and index is always delivered to event listeners on subscription, but intermediate (next-to-last) events for each symbol+index pair are not queued anywhere, they are simply discarded as stale events. More recent events represent an up-to-date information about some external entity.
Event flags, transactions and snapshots
Some indexed event sources provide a consistent view of a set of events for a given symbol. Their updates may incorporate multiple changes that have to be processed at the same time. The corresponding information is carried in eventFlags property. Some indexed events, like Order, support multiple sources of information for the same symbol. The event source is available via source property. The value of source property is always DEFAULT for time-series events and other singe-sourced events like Series, that do not support this feature.
The value of eventFlags property has several significant bits that are packed into an integer in the following way:
```
    31..7    6    5    4    3    2    1    0
 +---------+----+----+----+----+----+----+----+
 |         | SM |    | SS | SE | SB | RE | TX |
 +---------+----+----+----+----+----+----+----+
 
```
Each source updates its transactional state using these bits separately. The state of each source has to be tracked separately in a map for each source. However, event index is unique across the sources. This is achieved by allocating an event-specific number of most significant bits of index for use as a source id.
TX (bit 0) — TX_PENDING is an indicator of pending transactional update. It can be retrieved from eventFlags with the following piece of code:
boolean txPending = (event.getEventFlags() & IndexedEvent.TX_PENDING) != 0;
When txPending is true it means, that an ongoing transaction update that spans multiple events is in process. All events with txPending true shall be put into a separate pending list for each source id and should be processed later when an event for this source id with txPending false comes.
RE (bit 1) — REMOVE_EVENT is used to indicate that that the event with the corresponding index has to be removed.
boolean removeEvent = (event.getEventFlags() & IndexedEvent.REMOVE_EVENT) != 0;
SB (bit 2) — SNAPSHOT_BEGIN is used to indicate when the loading of a snapshot starts.
boolean snapshotBegin = (event.getEventFlags() & IndexedEvent.SNAPSHOT_BEGIN) != 0;
Snapshot load starts on new subscription and the first indexed event that arrives for each non-zero source id on new subscription may have snapshotBegin set to true. It means, that an ongoing snapshot consisting of multiple events is incoming. All events for this source id shall be put into a separate pending list for each source id.
SE (bit 3) — SNAPSHOT_END or SS (bit 4) — SNAPSHOT_SNIP are used to indicate the end of a snapshot.
boolean snapshotEnd = (event.getEventFlags() & IndexedEvent.SNAPSHOT_END) != 0;
boolean snapshotSnip = (event.getEventFlags() & IndexedEvent.SNAPSHOT_SNIP) != 0;
The last event of a snapshot is marked with either snapshotEnd or snapshotSnip. At this time, all events from a pending list for the corresponding source can be processed, unless txPending is also set to true. In the later case, the processing shall be further delayed due to ongoing transaction.
The difference between snapshotEnd and snapshotSnip is the following. snapshotEnd indicates that the data source had sent all the data pertaining to the subscription for the corresponding indexed event, while snapshotSnip indicates that some limit on the amount of data was reached and while there still might be more data available, it will not be provided.
SM (bit 6) — SNAPSHOT_MODE is used to instruct dxFeed to use snapshot mode. It is intended to be used only for publishing to activate (if not yet activated) snapshot mode. The difference from SNAPSHOT_BEGIN flag is that SNAPSHOT_MODE only switches on snapshot mode without starting snapshot synchronization protocol.
When a snapshot is empty or consists of a single event, then the event can have both snapshotBegin and snapshotEnd or snapshotSnip flags. In case of an empty snapshot, removeEvent on this event is also set to true.

Field Summary

Fields
Modifier and Type	Field and Description
`static int`	`REMOVE_EVENT` Bit mask to get removal indicator from the value of `eventFlags` property.
`static int`	`SNAPSHOT_BEGIN` Bit mask to get snapshot begin indicator from the value of `eventFlags` property.
`static int`	`SNAPSHOT_END` Bit mask to get snapshot end indicator from the value of `eventFlags` property.
`static int`	`SNAPSHOT_MODE` Bit mask to set snapshot mode indicator into the value of `eventFlags` property.
`static int`	`SNAPSHOT_SNIP` Bit mask to get snapshot snip indicator from the value of `eventFlags` property.
`static int`	`TX_PENDING` Bit mask to get transaction pending indicator from the value of `eventFlags` property.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method and Description
`int`	`getEventFlags()` Returns transactional event flags.
`long`	`getIndex()` Returns unique per-symbol index of this event.
`IndexedEventSource`	`getSource()` Returns source of this event.
`void`	`setEventFlags(int eventFlags)` Changes transactional event flags.
`void`	`setIndex(long index)` Changes unique per-symbol index of this event.

Methods inherited from interface com.dxfeed.event.EventType
getEventSymbol, getEventTime, setEventSymbol, setEventTime

- Field Detail
  - TX_PENDING
```
static final int TX_PENDING
```
    Bit mask to get transaction pending indicator from the value of eventFlags property.
    boolean txPending = (event.getEventFlags() & IndexedEvent.TX_PENDING) != 0;
    See "Event Flags" section.
    
    See Also:
    
    Constant Field Values
  - REMOVE_EVENT
```
static final int REMOVE_EVENT
```
    Bit mask to get removal indicator from the value of eventFlags property.
    boolean removeEvent = (event.getEventFlags() & IndexedEvent.REMOVE_EVENT) != 0;
    See "Event Flags" section.
    
    See Also:
    
    Constant Field Values
  - SNAPSHOT_BEGIN
```
static final int SNAPSHOT_BEGIN
```
    Bit mask to get snapshot begin indicator from the value of eventFlags property.
    boolean snapshotBegin = (event.getEventFlags() & IndexedEvent.SNAPSHOT_BEGIN) != 0;
    See "Event Flags" section.
    
    See Also:
    
    Constant Field Values
  - SNAPSHOT_END
```
static final int SNAPSHOT_END
```
    Bit mask to get snapshot end indicator from the value of eventFlags property.
    boolean snapshotEnd = (event.getEventFlags() & IndexedEvent.SNAPSHOT_END) != 0;
    See "Event Flags" section.
    
    See Also:
    
    Constant Field Values
  - SNAPSHOT_SNIP
```
static final int SNAPSHOT_SNIP
```
    Bit mask to get snapshot snip indicator from the value of eventFlags property.
    boolean snapshotSnip = (event.getEventFlags() & IndexedEvent.SNAPSHOT_SNIP) != 0;
    See "Event Flags" section.
    
    See Also:
    
    Constant Field Values
  - SNAPSHOT_MODE
```
static final int SNAPSHOT_MODE
```
    Bit mask to set snapshot mode indicator into the value of eventFlags property. This flag is intended for publishing only. See "Event Flags" section.
    
    See Also:
    
    Constant Field Values
- Method Detail
  - getSource
```
IndexedEventSource getSource()
```
    Returns source of this event.
    
    Returns:
    
    source of this event.
  - getEventFlags
```
int getEventFlags()
```
    Returns transactional event flags. See "Event Flags" section.
    
    Returns:
    
    transactional event flags.
  - setEventFlags
```
void setEventFlags(int eventFlags)
```
    Changes transactional event flags. See "Event Flags" section.
    
    Parameters:
    
    eventFlags - transactional event flags.
    
    Throws:
    
    IllegalArgumentException - if unsupported event flag is set in eventFlags.
  - getIndex
```
long getIndex()
```
    Returns unique per-symbol index of this event.
    
    Returns:
    
    unique per-symbol index of this event.
  - setIndex
```
void setIndex(long index)
```
    Changes unique per-symbol index of this event.
    
    Parameters:
    
    index - unique per-symbol index of this event.

Interface IndexedEvent<T>

Event flags, transactions and snapshots

Field Summary

Method Summary

Methods inherited from interface com.dxfeed.event.EventType

Field Detail

TX_PENDING

REMOVE_EVENT

SNAPSHOT_BEGIN

SNAPSHOT_END

SNAPSHOT_SNIP

SNAPSHOT_MODE

Method Detail

getSource

getEventFlags

setEventFlags

getIndex

setIndex