The root element of a DDSI2E networking service configuration.
2.4 General
The General element specifies overall DDSI2E settings.
- Full path: DDSI2E/General
- Occurrences min-max: 0-1
- Child elements: AllowMulticast, EnableLoopback, DontRoute, EnableMulticastLoopback, ExternalNetworkAddress, ExternalNetworkMask, MulticastRecvNetworkInterfaceAddresses, MulticastTimeToLive, NetworkInterfaceAddress, StartupModeCoversTransient, StartupModeDuration, UseIPv6
2.4.1 AllowMulticast
This element controls whether DDSI2E uses multicasts for data traffic.
It is a comma-separated list of some of the following keywords: “spdp”, “asm”, “ssm”, or either of “false” or “true”.
- spdp: enables the use of ASM (any-source multicast) for participant discovery
- asm: enables the use of ASM for all traffic (including SPDP)
- ssm: enables the use of SSM (source-specific multicast) for all non-SPDP traffic (if supported)
When set to “false” all multicasting is disabled. The default, “true” enables full use of multicasts. Listening for multicasts can be controlled by General/MulticastRecvNetworkInterfaceAddresses.
- Full path: DDSI2E/General/AllowMulticast
- Format: string
- Default value: true
- Occurrences min-max: 0-1
2.4.2 EnableLoopback
This element specifies whether DDSI packets are visible to all DDSI participants in the same process. It must be \”true\” for intra-process communications, i.e. a reader and writer communicating in the same address space. If enabled and using multicast then EnableMulticastLoopback must also be enabled.
- Full path: DDSI2E/General/EnableLoopback
- Format: boolean
- Default value: false
- Occurrences min-max: 0-1
2.4.3 DontRoute
This element allows setting the SO_DONTROUTE option for outgoing packets, to bypass the local routing tables. This is generally useful only when the routing tables cannot be trusted, which is highly unusual.
- Full path: DDSI2E/General/DontRoute
- Format: boolean
- Default value: false
- Occurrences min-max: 0-1
2.4.4 EnableMulticastLoopback
This element specifies whether DDSI2E allows IP multicast packets to be visible to all DDSI participants in the same node, including itself. It must be “true” for intra-node multicast communications, but if a node runs only a single DDSI2E service and does not host any other DDSI-capable programs, it should be set to “false” for improved performance.
- Full path: DDSI2E/General/EnableMulticastLoopback
- Format: boolean
- Default value: true
- Occurrences min-max: 0-1
2.4.5 ExternalNetworkAddress
This element allows explicitly overruling the network address DDSI2E advertises in the discovery protocol, which by default is the address of the preferred network interface (General/NetworkInterfaceAddress), to allow DDSI2E to communicate across a Network Address Translation (NAT) device.
- Full path: DDSI2E/General/ExternalNetworkAddress
- Format: string
- Default value: auto
- Occurrences min-max: 0-1
2.4.6 ExternalNetworkMask
This element specifies the network mask of the external network address. This element is relevant only when an external network address (General/ExternalNetworkAddress) is explicitly configured. In this case locators received via the discovery protocol that are within the same external subnet (as defined by this mask) will be translated to an internal address by replacing the network portion of the external address with the corresponding portion of the preferred network interface address. This option is IPv4-only.
- Full path: DDSI2E/General/ExternalNetworkMask
- Format: string
- Default value: 0.0.0.0
- Occurrences min-max: 0-1
2.4.7 MulticastRecvNetworkInterfaceAddresses
This element specifies on which network interfaces DDSI2E listens to multicasts. The following options are available:
- all: listen for multicasts on all multicast-capable interfaces; or
- any: listen for multicasts on the operating system default interface; or
- preferred: listen for multicasts on the preferred interface (General/NetworkInterfaceAddress); or
- none: does not listen for multicasts on any interface; or
- a comma-separated list of network addresses: configures DDSI2E to listen for multicasts on all of the listed addresses.
If DDSI2E is in IPv6 mode and the address of the preferred network interface is a link-local address, “all” is treated as a synonym for “preferred” and a comma-separated list is treated as “preferred” if it contains the preferred interface and as “none” if not.
- Full path: DDSI2E/General/MulticastRecvNetworkInterfaceAddresses
- Format: string
- Default value: preferred
- Occurrences min-max: 0-1
2.4.8 MulticastTimeToLive
This element specifies the time-to-live setting for outgoing multicast packets.
- Full path: DDSI2E/General/MulticastTimeToLive
- Format: integer
- Default value: 32
- Occurrences min-max: 0-1
2.4.9 NetworkInterfaceAddress
This element specifies the preferred network interface for use by DDSI2E. The preferred network interface determines the IP address that DDSI2E advertises in the discovery protocol (but see also General/ExternalNetworkAddress), and is also the only interface over which multicasts are transmitted. The interface can be identified by its IP address, network interface name or network portion of the address. If the value “auto” is entered here, DDSI2E will select what it considers the most suitable interface.
- Full path: DDSI2E/General/NetworkInterfaceAddress
- Format: string
- Default value: auto
- Occurrences min-max: 0-1
2.4.10 StartupModeCoversTransient
This element configures whether startup-mode should also cover transient and persistent data, for configurations where the durability service does not take care of it. Configurations without defined merge policies best leave this enabled.
- Full path: DDSI2E/General/StartupModeCoversTransient
- Format: boolean
- Default value: true
- Occurrences min-max: 0-1
2.4.11 StartupModeDuration
This element specifies how long the DDSI2E remains in its “startup” mode. While in “startup” mode all volatile reliable data published on the local node is retained as-if it were transient-local data, allowing existing readers on remote nodes to obtain the data even though discovering them takes some time. Best-effort data by definition need not arrive, and transient and persistent data are covered by the durability service.
Once the system is stable, DDSI2E keeps track of the existence of remote readers whether or not matching writers exist locally, avoiding this discovery delay and ensuring this is merely a node startup issue.
Setting General/StartupModeDuration to 0s will disable it.
The unit must be specified explicitly. Recognised units: ns, us, ms, s, min, hr, day.
- Full path: DDSI2E/General/StartupModeDuration
- Format: string
- Default value: 2 s
- Occurrences min-max: 0-1
2.4.12 UseIPv6
This element can be used to DDSI2E use IPv6 instead of IPv4. This is currently an either/or switch.
- Full path: DDSI2E/General/UseIPv6
- Format: boolean
- Default value: false
- Occurrences min-max: 0-1
2.5 Internal
The Internal elements deal with a variety of settings that are still evolving.
- Full path: DDSI2E/Internal
- Occurrences min-max: 0-1
- Child elements: AccelerateRexmitBlockSize, AggressiveKeepLast1Whc, AssumeMulticastCapable, AuxiliaryBandwidthLimit, BuiltinEndpointSet, ConservativeBuiltinReaderStartup, DDSI2DirectMaxThreads, DefragReliableMaxSamples, DefragUnreliableMaxSamples, DeliveryQueueMaxSamples, ForwardAllMessages, FragmentSize, GenerateKeyhash, LateAckMode, LeaseDuration, LegacyFragmentation, MaxMessageSize, LogStackTraces, MaxParticipants, MaxQueuedRexmitBytes, MaxQueuedRexmitMessages, MaxSampleSize, MeasureHbToAckLatency, MinimumSocketReceiveBufferSize, MinimumSocketSendBufferSize, NackDelay, PreEmptiveAckDelay, PrimaryReorderMaxSamples, RetransmitMerging, RetransmitMergingPeriod, RetryOnRejectBestEffort, RetryOnRejectDuration, SPDPResponseMaxDelay, ScheduleTimeRounding, SecondaryReorderMaxSamples, SquashParticipants, SuppressSPDPMulticast, SynchronousDeliveryLatencyBound, SynchronousDeliveryPriorityThreshold, UnicastResponseToSPDPMessages, WriteBatch, WriterLingerDuration
2.5.1 AccelerateRexmitBlockSize
Internal Proxy readers that are assumed to sill be retrieving historical data get this many samples retransmitted when they NACK something, even if some of these samples have sequence numbers outside the set covered by the NACK.
- Full path: DDSI2E/Internal/AccelerateRexmitBlockSize
- Format: integer
- Default value: 0
- Occurrences min-max: 0-1
2.5.2 AggressiveKeepLast1Whc
Internal This element controls whether to drop a reliable sample from a DDSI2E WHC before all readers have acknowledged it as soon as a later sample becomes available. It only affects DCPS data writers with a history QoS setting of KEEP_LAST with depth 1.
- Full path: DDSI2E/Internal/AggressiveKeepLast1Whc
- Format: boolean
- Default value: false
- Occurrences min-max: 0-1
2.5.3 AssumeMulticastCapable
Internal This element controls which network interfaces are assumed to be capable of multicasting even when the interface flags returned by the operating system state it is not (this provides a workaround for some platforms). It is a comma-separated lists of patterns (with ? and * wildcards) against which the interface names are matched.
- Full path: DDSI2E/Internal/AssumeMulticastCapable
- Format: string
- Occurrences min-max: 0-1
2.5.4 AuxiliaryBandwidthLimit
Internal This element specifies the maximum transmit rate of auxiliary traffic not bound to a specific channel, such as discovery traffic, as well as auxiliary traffic related to a certain channel if that channel has elected to share this global AuxiliaryBandwidthLimit. Bandwidth limiting uses a leaky bucket scheme. The default value “inf” means DDSI2E imposes no limitation, the underlying operating system and hardware will likely limit the maimum transmit rate.
The unit must be specified explicitly. Recognised units: X*b/s, *X*bps for bits/s or *X*B/s, *X*Bps for bytes/s; where *X is an optional prefix: k for 10 3, Ki for 2 10, M for 10 6, Mi for 2 20, G for 10 9, Gi for 2 30.
- Full path: DDSI2E/Internal/AuxiliaryBandwidthLimit
- Format: string
- Default value: inf
- Occurrences min-max: 0-1
2.5.5 BuiltinEndpointSet
Internal This element controls which participants will have which built-in endpoints for the discovery and liveliness protocols. Valid values are:
- full: all participants have all endpoints;
- writers: all participants have the writers, but just one has the readers;
- minimal: only one participant has built-in endpoints.
The default is writers, as this is thought to be compliant and reasonably efficient. Minimal may or may not be compliant but is most efficient, and full is inefficient but certain to be compliant. See also Internal/ConservativeBuiltinReaderStartup.
- Full path: DDSI2E/Internal/BuiltinEndpointSet
- Format: enumeration
- Default value: writers
- Valid values: full, writers, minimal
- Occurrences min-max: 0-1
2.5.6 ConservativeBuiltinReaderStartup
Internal This element forces all DDSI2E built-in discovery-related readers to request all historical data, instead of just one for each “topic”. There is no indication that any of the current DDSI implementations requires changing of this setting, but it is conceivable that an implementation might track which participants have been informed of the existence of endpoints and which have not been, refusing communication with those that have “can’t” know.
Should it be necessary to hide DDSI2E’s shared discovery behaviour, set this to true and Internal/BuiltinEndpointSet to full.
- Full path: DDSI2E/Internal/ConservativeBuiltinReaderStartup
- Format: boolean
- Default value: false
- Occurrences min-max: 0-1
2.5.7 DDSI2DirectMaxThreads
Internal This element sets the maximum number of extra threads for an experimental, undocumented and unsupported direct mode.
- Full path: DDSI2E/Internal/DDSI2DirectMaxThreads
- Format: integer
- Default value: 1
- Occurrences min-max: 0-1
2.5.8 DefragReliableMaxSamples
Internal This element sets the maximum number of samples that can be defragmented simultaneously for a reliable writer. This has to be large enough to handle retransmissions of historical data in addition to new samples.
- Full path: DDSI2E/Internal/DefragReliableMaxSamples
- Format: integer
- Default value: 16
- Occurrences min-max: 0-1
2.5.9 DefragUnreliableMaxSamples
Internal This element sets the maximum number of samples that can be defragmented simultaneously for a best-effort writers.
- Full path: DDSI2E/Internal/DefragUnreliableMaxSamples
- Format: integer
- Default value: 4
- Occurrences min-max: 0-1
2.5.10 DeliveryQueueMaxSamples
Internal This element controls the Maximum size of a delivery queue, expressed in samples. Once a delivery queue is full, incoming samples destined for that queue are dropped until space becomes available again.
- Full path: DDSI2E/Internal/DeliveryQueueMaxSamples
- Format: integer
- Default value: 256
- Occurrences min-max: 0-1
2.5.11 ForwardAllMessages
Internal Forward all messages from a writer, rather than trying to forward each sample only once. The default of trying to forward each sample only once filters out duplicates for writers in multiple partitions under nearly all circumstances, but may still publish the odd duplicate. Note: the current implementation also can lose in contrived test cases, that publish more than 2**32 samples using a single data writer in conjunction with carefully controlled management of the writer history via cooperating local readers.
- Full path: DDSI2E/Internal/ForwardAllMessages
- Format: boolean
- Default value: false
- Occurrences min-max: 0-1
2.5.12 FragmentSize
Internal This element specifies the size of DDSI sample fragments generated by DDSI2E. Samples larger than FragmentSize are fragmented into fragments of FragmentSize bytes each, except the last one, which may be smaller. The DDSI spec mandates a minimum fragment size of 1025 bytes, but DDSI2E will do whatever size is requested, accepting fragments of which the size is at least the minimum of 1025 and FragmentSize.
The unit must be specified explicitly. Recognised units: B (bytes), kB & KiB (2 10 bytes), MB & MiB (2 20 bytes), GB & GiB (2 30 bytes).
- Full path: DDSI2E/Internal/FragmentSize
- Format: string
- Default value: 1280 B
- Occurrences min-max: 0-1
2.5.13 GenerateKeyhash
Internal When true, include keyhashes in outgoing data for topics with keys.
- Full path: DDSI2E/Internal/GenerateKeyhash
- Format: boolean
- Default value: true
- Occurrences min-max: 0-1
2.5.14 LateAckMode
Internal Ack a sample only when it has been delivered, instead of when committed to delivering it.
- Full path: DDSI2E/Internal/LateAckMode
- Format: boolean
- Default value: false
- Occurrences min-max: 0-1
2.5.15 LeaseDuration
Internal This setting controls the default participant lease duration.
- Full path: DDSI2E/Internal/LeaseDuration
- Format: string
- Default value: 10 s
- Occurrences min-max: 0-1
2.5.16 LegacyFragmentation
Internal This option enables a backwards-compatible, non-compliant setting and interpretation of the control flags in fragmented data messages. To be enabled only when requiring interoperability between compliant and non-compliant versions of DDSI2E for large messages.
- Full path: DDSI2E/Internal/LegacyFragmentation
- Format: boolean
- Default value: false
- Occurrences min-max: 0-1
2.5.17 MaxMessageSize
Internal This element specifies the maximum size of the UDP payload that DDSI2E will generate. DDSI2E will try to maintain this limit within the bounds of the DDSI specification, which means that in some cases (especially for very low values of MaxMessageSize) larger payloads may sporadically be observed (currently up to 1192 B).
On some networks it may be necessary to set this item to keep the packetsize below the MTU to prevent IP fragmentation. In those cases, it is generally advisable to also consider reducing Internal/FragmentSize.
The unit must be specified explicitly. Recognised units: B (bytes), kB & KiB (2 10 bytes), MB & MiB (2 20 bytes), GB & GiB (2 30 bytes).
- Full path: DDSI2E/Internal/MaxMessageSize
- Format: string
- Default value: 4096 B
- Occurrences min-max: 0-1
2.5.18 LogStackTraces
This element controls whether or not to write stack traces to the DDSI2 trace when a thread fails to make progress (on select platforms only).
- Full path: DDSI2E/Internal/LogStackTraces
- Format: boolean
- Default value: false
- Occurrences min-max: 0-1
2.5.19 MaxParticipants
Internal This elements configures the maximum number of DCPS domain participants this DDSI2E instance is willing to service. 0 is unlimited.
- Full path: DDSI2E/Internal/MaxParticipants
- Format: integer
- Default value: 0
- Occurrences min-max: 0-1
2.5.20 MaxQueuedRexmitBytes
Internal This setting limits the maximum number of bytes queued for retransmission. The default value of 0 is unlimited unless an AuxiliaryBandwidthLimit has been set, in which case it becomes NackDelay * AuxiliaryBandwidthLimit. It must be large enough to contain the largest sample that may need to be retransmitted.
The unit must be specified explicitly. Recognised units: B (bytes), kB & KiB (2 10 bytes), MB & MiB (2 20 bytes), GB & GiB (2 30 bytes).
- Full path: DDSI2E/Internal/MaxQueuedRexmitBytes
- Format: string
- Default value: 0 B
- Occurrences min-max: 0-1
2.5.21 MaxQueuedRexmitMessages
Internal This settings limits the maximum number of samples queued for retransmission.
- Full path: DDSI2E/Internal/MaxQueuedRexmitMessages
- Format: integer
- Default value: 200
- Occurrences min-max: 0-1
2.5.22 MaxSampleSize
Internal This setting controls the maximum (CDR) serialised size of samples that DDSI2E will forward in either direction. Samples larger than this are discarded with a warning.
The unit must be specified explicitly. Recognised units: B (bytes), kB & KiB (2 10 bytes), MB & MiB (2 20 bytes), GB & GiB (2 30 bytes).
- Full path: DDSI2E/Internal/MaxSampleSize
- Format: string
- Default value: 2147483647 B
- Occurrences min-max: 0-1
2.5.23 MeasureHbToAckLatency
Internal This element enables heartbeat-to-ack latency among DDSI2E services by prepending timestamps to Heartbeat and AckNack messages and calculating round trip times. This is non-standard behaviour. The measured latencies are quite noisy and are currently not used anywhere.
- Full path: DDSI2E/Internal/MeasureHbToAckLatency
- Format: boolean
- Default value: false
- Occurrences min-max: 0-1
2.5.24 MinimumSocketReceiveBufferSize
Internal This setting controls the minimum size of socket receive buffers. The operating system provides some size receive buffer upon creation of the socket, this option can be used to increase the size of the buffer beyond that initially provided by the operating system. If the buffer size cannot be increased to the specified size, an error is reported.
The default setting is the word “default”, which means DDSI2E will attempt to increase the buffer size to 1MB, but will silently accept a smaller buffer should that attempt fail.
The unit must be specified explicitly. Recognised units: B (bytes), kB & KiB (2 10 bytes), MB & MiB (2 20 bytes), GB & GiB (2 30 bytes).
- Full path: DDSI2E/Internal/MinimumSocketReceiveBufferSize
- Format: string
- Default value: default
- Occurrences min-max: 0-1
2.5.25 MinimumSocketSendBufferSize
Internal This setting controls the minimum size of socket send buffers. This setting can only increase the size of the send buffer, if the operating system by default creates a larger buffer, it is left unchanged.
The unit must be specified explicitly. Recognised units: B (bytes), kB & KiB (2 10 bytes), MB & MiB (2 20 bytes), GB & GiB (2 30 bytes).
- Full path: DDSI2E/Internal/MinimumSocketSendBufferSize
- Format: string
- Default value: 64 KiB
- Occurrences min-max: 0-1
2.5.26 NackDelay
Internal This setting controls the delay between receipt of a HEARTBEAT indicating missing samples and a NACK (ignored when the HEARTBEAT requires an answer). However, no NACK is sent if a NACK had been scheduled already for a response earlier than the delay requests: then that NACK will incorporate the latest information.
The unit must be specified explicitly. Recognised units: ns, us, ms, s, min, hr, day.
- Full path: DDSI2E/Internal/NackDelay
- Format: string
- Default value: 10 ms
- Occurrences min-max: 0-1
2.5.27 PreEmptiveAckDelay
Internal This setting controls the delay between the discovering a remote writer and sending a pre-emptive AckNack to discover the range of data available.
The unit must be specified explicitly. Recognised units: ns, us, ms, s, min, hr, day.
- Full path: DDSI2E/Internal/PreEmptiveAckDelay
- Format: string
- Default value: 10 ms
- Occurrences min-max: 0-1
2.5.28 PrimaryReorderMaxSamples
Internal This element sets the maximum size in samples of a primary re-order administration. Each proxy writer has one primary re-order administration to buffer the packet flow in case some packets arrive out of order. Old samples are forwarded to secondary re-order administrations associated with readers in need of historical data.
- Full path: DDSI2E/Internal/PrimaryReorderMaxSamples
- Format: integer
- Default value: 64
- Occurrences min-max: 0-1
2.5.29 RetransmitMerging
Internal This elements controls the addressing and timing of retransmits. Possible values are:
- never: retransmit only to the NACK-ing reader;
- adaptive: attempt to combine retransmits needed for reliability, but send historical (transient-local) data to the requesting reader only;
- always: do not distinguish between different causes, always try to merge.
The default is adaptive. See also Internal/RetransmitMergingPeriod.
- Full path: DDSI2E/Internal/RetransmitMerging
- Format: enumeration
- Default value: adaptive
- Valid values: never, adaptive, always
- Occurrences min-max: 0-1
2.5.30 RetransmitMergingPeriod
Internal This setting determines the size of the time window in which a NACK of some sample is ignored because a retransmit of that sample has been multicasted too recently. This setting has no effect on unicasted retransmits.
See also Internal/RetransmitMerging.
The unit must be specified explicitly. Recognised units: ns, us, ms, s, min, hr, day.
- Full path: DDSI2E/Internal/RetransmitMergingPeriod
- Format: string
- Default value: 5 ms
- Occurrences min-max: 0-1
2.5.31 RetryOnRejectBestEffort
Internal Whether or not to locally retry pushing a received best-effort sample into the reader caches when resource limits are reached.
- Full path: DDSI2E/Internal/RetryOnRejectBestEffort
- Format: boolean
- Default value: false
- Occurrences min-max: 0-1
2.5.32 RetryOnRejectDuration
Internal How long to keep locally retrying pushing a received sample into the reader caches when resource limits are reached. Default is dependent on Internal/LateAckMode: if the latter is false, it is 80% of Internal/ResponsivenessTimeout, otherwise it is 0.
Valid values are finite durations with an explicit unit or the keyword ‘inf’ for infinity. Recognised units: ns, us, ms, s, min, hr, day.
- Full path: DDSI2E/Internal/RetryOnRejectDuration
- Format: string
- Default value: default
- Occurrences min-max: 0-1
2.5.33 SPDPResponseMaxDelay
Internal Maximum pseudo-random delay in milliseconds between discovering a remote participant and responding to it.
The unit must be specified explicitly. Recognised units: ns, us, ms, s, min, hr, day.
- Full path: DDSI2E/Internal/SPDPResponseMaxDelay
- Format: string
- Default value: 0 ms
- Occurrences min-max: 0-1
2.5.34 ScheduleTimeRounding
Internal This setting allows the timing of scheduled events to be rounded up so that more events can be handled in a single cycle of the event queue. The default is 0 and causes no rounding at all, i.e. are scheduled exactly, whereas a value of 10ms would mean that events are rounded up to the nearest 10 milliseconds.
The unit must be specified explicitly. Recognised units: ns, us, ms, s, min, hr, day.
- Full path: DDSI2E/Internal/ScheduleTimeRounding
- Format: string
- Default value: 0 ms
- Occurrences min-max: 0-1
2.5.35 SecondaryReorderMaxSamples
Internal This element sets the maximum size in samples of a secondary re-order administration. The secondary re-order administration is per reader in need of historical data.
- Full path: DDSI2E/Internal/SecondaryReorderMaxSamples
- Format: integer
- Default value: 16
- Occurrences min-max: 0-1
2.5.36 SquashParticipants
Internal This element controls whether DDSI2E advertises all the domain participants it serves in DDSI (when set to false), or rather only one domain participant (the one corresponding to the DDSI2E process; when set to true). In the latter case DDSI2E becomes the virtual owner of all readers and writers of all domain participants, dramatically reducing discovery traffic.
- Full path: DDSI2E/Internal/SquashParticipants
- Format: boolean
- Default value: false
- Occurrences min-max: 0-1
2.5.37 SuppressSPDPMulticast
Internal The element controls whether the mandatory multicasting of the participant discovery packets occurs. Completely disabling multicasting requires this element be set to true, and generally requires explicitly listing peers to ping for unicast discovery.
See also General/AllowMulticast.
- Full path: DDSI2E/Internal/SuppressSPDPMulticast
- Format: boolean
- Default value: false
- Occurrences min-max: 0-1
2.5.38 SynchronousDeliveryLatencyBound
Internal This element controls whether samples sent by a writer with QoS settings transport_priority >= SynchronousDeliveryPriorityThreshold and a latency_budget at most this element’s value will be delivered synchronously from the “recv” thread, all others will be delivered asynchronously through delivery queues. This reduces latency at the expense of aggregate bandwidth.
Valid values are finite durations with an explicit unit or the keyword ‘inf’ for infinity. Recognised units: ns, us, ms, s, min, hr, day.
- Full path: DDSI2E/Internal/SynchronousDeliveryLatencyBound
- Format: string
- Default value: inf
- Occurrences min-max: 0-1
2.5.39 SynchronousDeliveryPriorityThreshold
Internal This element controls whether samples sent by a writer with QoS settings latency_budget <= SynchronousDeliveryLatencyBound and transport_priority greater than or equal to this element’s value will be delivered synchronously from the “recv” thread, all others will be delivered asynchronously through delivery queues. This reduces latency at the expense of aggregate bandwidth.
- Full path: DDSI2E/Internal/SynchronousDeliveryPriorityThreshold
- Format: integer
- Default value: 0
- Occurrences min-max: 0-1
2.5.40 Test
Internal Testing options.
The unit must be specified explicitly.
- Full path: DDSI2E/Internal/Test
- Occurrences min-max: 0-1
- Child elements: XmitLossiness
2.5.40.1 XmitLossiness
Internal This element controls the fraction of outgoing packets to drop, specified as samples per thousand.
- Full path: DDSI2E/Internal/Test/XmitLossiness
- Format: integer
- Default value: 0
- Occurrences min-max: 0-1
2.5.41 UnicastResponseToSPDPMessages
Internal This element controls whether the response to a newly discovered participant is sent as a unicasted SPDP packet, instead of rescheduling the periodic multicasted one. There is no known benefit to setting this to false.
- Full path: DDSI2E/Internal/UnicastResponseToSPDPMessages
- Format: boolean
- Default value: true
- Occurrences min-max: 0-1
2.5.42 Watermarks
Internal Watermarks for flow-control.
The unit must be specified explicitly. Recognised units: B (bytes), kB & KiB (2 10 bytes), MB & MiB (2 20 bytes), GB & GiB (2 30 bytes).
- Full path: DDSI2E/Internal/Watermarks
- Occurrences min-max: 0-1
- Child elements: WhcHigh, WhcLow
2.5.42.1 WhcHigh
Internal This element sets the high-water mark for the DDSI2E WHCs, expressed in bytes. A writer is suspended when the WHC reaches this size.
The unit must be specified explicitly. Recognised units: B (bytes), kB & KiB (2 10 bytes), MB & MiB (2 20 bytes), GB & GiB (2 30 bytes).
- Full path: DDSI2E/Internal/Watermarks/WhcHigh
- Format: string
- Default value: 100 kB
- Occurrences min-max: 0-1
2.5.42.2 WhcLow
Internal This element sets the low-water mark for the DDSI2E WHCs, expressed in bytes. A suspended writer resumes transmitting when its DDSI2E WHC shrinks to this size.
The unit must be specified explicitly. Recognised units: B (bytes), kB & KiB (2 10 bytes), MB & MiB (2 20 bytes), GB & GiB (2 30 bytes).
- Full path: DDSI2E/Internal/Watermarks/WhcLow
- Format: string
- Default value: 1 kB
- Occurrences min-max: 0-1
2.5.43 WriteBatch
This element enables the batching of write operations. By default each write operation writes through the write
cache and out onto the transport. Enabling write batching causes multiple small write operations to be aggregated within the write cache into a single larger write. This gives greater throughput at the expense of latency. Currently there is no
mechanism for the write cache to automatically flush itself, so that if write batching is enabled, the application may havee to use the dds_write_flush function to ensure thta all samples are written.
- Full path: DDSI2E/Internal/WriteBatch
- Format: boolean
- Default value: false
- Occurrences min-max: 0-1
2.5.44 WriterLingerDuration
Internal This setting controls the maximum duration for which actual deletion of a reliable writer with unacknowledged data in its history will be postponed to provide proper reliable transmission.
The unit must be specified explicitly. Recognised units: ns, us, ms, s, min, hr, day.
- Full path: DDSI2E/Internal/WriterLingerDuration
- Format: string
- Default value: 1 s
- Occurrences min-max: 0-1