C# — Enums & Constants

Enums are defined in the Nnrp.Core namespace and shared across all other namespaces.

Import

using Nnrp.Core;

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Wire Format

WireFormat

Member	Value	Description
Current	0	Only supported wire format (NNRP/1)

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Message Types

MessageType

Member	Value	Direction	Description
ClientHello	0x01	C→S	Connection setup
ServerHelloAck	0x02	S→C	Handshake acknowledgement
SessionPatch	0x03	C→S	Session parameter update request
SessionPatchAck	0x04	S→C	Session parameter update result
Close	0x05	Both	Graceful close
Error	0x06	Both	Protocol error notification
FrameSubmit	0x10	C→S	Submit a frame
FrameCancel	0x11	C→S	Cancel a frame
ResultPush	0x12	S→C	Push inference result
ResultDrop	0x13	S→C	Notify result dropped
CachePut	0x14	C→S	Store a cache object
CacheAck	0x15	S→C	Cache store result
CacheInvalidate	0x16	C→S	Invalidate cache
FlowUpdate	0x17	Both	Flow control window update
ResultHint	0x18	S→C	Server hint
TransportProbe	0x19	Both	Transport path probe
TransportProbeAck	0x1A	Both	Path probe acknowledgement
SessionMigrate	0x1B	S→C	Session migration notification
SessionMigrateAck	0x1C	C→S	Session migration confirmation
Ping	0x20	Both	Keep-alive probe
Pong	0x21	Both	Keep-alive response

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Header Flags

HeaderFlags ([Flags])

Member	Mask	Description
None	0x00	No flags
AckRequired	0x01	Receiver must acknowledge
CanDrop	0x02	May be dropped under backpressure
Stale	0x04	Data is stale
Eos	0x08	End of stream
Retransmit	0x10	Retransmitted packet
Keyframe	0x20	Keyframe

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Frame Classification

FrameClass

Member	Value	Description
Keyframe	0	Complete keyframe
Delta	1	Delta frame
Retransmit	2	Retransmit frame
Discardable	3	May be skipped

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Error Codes

ErrorCode

Member	Value	Description
UnsupportedVersion	0x0001	Unsupported protocol version
AuthFailed	0x0002	Authentication failed
InvalidState	0x0003	Operation not allowed in current state
MalformedHeader	0x0004	Malformed header
MalformedBody	0x0005	Malformed body
UnsupportedCapability	0x0006	Unsupported capability
LimitExceeded	0x0007	Limit exceeded
FrameExpired	0x0008	Frame expired
FrameCancelled	0x0009	Frame cancelled by client
CacheMiss	0x000A	Cache object not found
ServerBusy	0x000B	Server temporarily unable to process
InternalError	0x000C	Server internal error

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Transport & Connection

TransportId

Member	Value	Description
Unspecified	0	Unspecified
Quic	1	QUIC transport
Tcp	2	TCP transport

TransportPolicy

Member	Value	Description
Auto	0	Automatic selection
PreferQuic	1	Prefer QUIC
PreferTcp	2	Prefer TCP
ForceQuic	3	Force QUIC
ForceTcp	4	Force TCP

LossTolerance

Member	Value	Description
Strict	0	No packet loss allowed
BestEffort	1	Best effort
LowLatency	2	Low latency preferred, minor loss tolerated
FireAndForget	3	High loss tolerance

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Data-plane Enums

InputProfile

Member	Value	Description
Unspecified	0	Unspecified
ChangedTilesLuma	1	Luma data for changed tiles only
DenseLumaFrame	2	Full-frame luma data

TileIndexMode

Member	Value	Description
DenseRange	0	Dense contiguous range
RawU16	1	Raw uint16 list
DeltaU16	2	Delta-encoded uint16
Bitset	3	Bitset encoding

DTypeId

Member	Value	Description
Fp16	0	Half-precision float
Fp32	1	Single-precision float
Fp8E4M3	2	FP8 E4M3
Fp8E5M2	3	FP8 E5M2
Int8	4	Signed 8-bit integer
Uint8	5	Unsigned 8-bit integer
Int16	6	Signed 16-bit integer
Uint16	7	Unsigned 16-bit integer

SubmitMode

Member	Value	Description
Inline	0	All objects inlined in body
Reference	1	Objects referenced via cache keys
Mixed	2	Mix of inline and reference

BudgetPolicy ([Flags])

Member	Mask	Description
None	0x00	Strict; no degradation
AllowPartial	0x01	Allow partial results
AllowStaleReuse	0x02	Allow stale cache reuse
AllowDegraded	0x04	Allow quality degradation
AllowDrop	0x08	Allow dropping the frame

ResultClass

Member	Value	Description
Complete	0	Complete result
Partial	1	Partial result
StaleReuse	2	Reused stale cached result
Degraded	3	Quality-degraded result

ResultFlags ([Flags])

Member	Mask	Description
None	0x0000	No flags
Stale	0x0001	Stale result
Fallback	0x0002	Fallback path used
Partial	0x0004	Incomplete result

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Cache Enums

CacheObjectKind

Member	Value	Description
CameraBlock	0x0001	Camera parameter block
TileIndexBlock	0x0002	Tile index block
TensorSectionTable	0x0003	Tensor section table
CodecTable	0x0004	Codec auxiliary table
ReusableResultObject	0x0005	Reusable result
PayloadLayoutTemplate	0x0006	Payload layout template
PromptSegment	0x0007	Prompt segment (LLM)
ToolSchema	0x0008	Tool schema
StructuredEventSchema	0x0009	Structured event schema

CacheAckStatus

Member	Value	Description
Stored	0	Successfully stored
Rejected	1	Rejected (capacity or policy)
Duplicate	2	Duplicate (already exists)

CacheInvalidateScope

Member	Value	Description
Single	0	Single object by key
ByKind	1	All objects of specified kind
All	2	All objects in session

CachePutFlags ([Flags])

Member	Mask	Description
None	0x00	Default
Pinned	0x01	Pinned; exempt from LRU eviction
Reusable	0x02	Cross-frame reusable

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Session Patch Enums

SessionPatchField ([Flags])

Member	Mask	Description
TargetCadence	0x0001	Target frame rate
QualityTier	0x0002	Quality tier
ActiveLaneMask	0x0004	Active view mask
PreferredCodec	0x0008	Preferred codec
PreferredCompression	0x0010	Preferred compression level

SessionPatchAckStatus

Member	Value	Description
Applied	0	Patch applied successfully
PartiallyApplied	1	Partially applied
Rejected	2	Patch rejected

SessionPatchRejectReason

Member	Value	Description
None	0	No rejection
InvalidValue	1	Invalid value
UnsupportedField	2	Unsupported field
StateConflict	3	Conflicts with current state

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Flow Control Enums

FlowUpdateScopeKind

Member	Value	Description
Connection	0	Connection level
Session	1	Session level
Operation	2	Operation level

FlowUpdateReason

Member	Value	Description
Grant	0	Grant more credit
Reduce	1	Reduce credit
Pause	2	Pause
Resume	3	Resume
Congestion	4	Congestion notification

FlowUpdateBackpressureLevel

Member	Value	Description
None	0	No backpressure
Soft	1	Soft (advisory)
Hard	2	Hard (mandatory)

FlowUpdateFlags ([Flags])

Member	Mask	Description
None	0x00	None
CreditValid	0x01	Credit field is valid
RetryAfterValid	0x02	RetryAfterMs is valid
BackgroundOnly	0x04	Applies only to background ops
DrainInFlightOnly	0x08	Takes effect after in-flight ops drain

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Use-Case Guide

Connecting and Negotiating Transport

var profile = new NnrpClientProfile
{
    TransportPolicy = TransportPolicy.PreferQuic,
    LossTolerance   = LossTolerance.LowLatency,
};

Pitfalls

• ForceQuic hard-fails in TCP-only firewalls. Use PreferQuic in production.
• LossTolerance.FireAndForget does not guarantee ordering; do not use it on the main frame path.

Submitting Frames with Budget Policy

var req = new NnrpSubmitRequest
{
    FrameId           = frameId,
    TileIds           = changedTiles,
    Sections          = new[] { tensorSection },
    InputProfile      = InputProfile.ChangedTilesLuma,
    SubmitMode        = SubmitMode.Inline,
    BudgetPolicy      = BudgetPolicy.AllowPartial | BudgetPolicy.AllowStaleReuse,
    InferenceBudgetMs = 8,
};

Pitfalls

• BudgetPolicy is a bitmask. Combine values with |.
• SubmitMode.Reference requires a prior PutCacheAsync() call.

Result Handling

switch (result.ResultClass)
{
    case ResultClass.Complete:   ApplyFull(result);   break;
    case ResultClass.Partial:    ApplyPartial(result); break;
    case ResultClass.StaleReuse: break;
    case ResultClass.Degraded:
        Log.Warn("Degraded: {0}", result.AppliedBudgetPolicy);
        break;
}

Error Handling

catch (NnrpProtocolException ex)
{
    if (ex.ErrorScope == ErrorScope.Connection)
    {
        await session.DisposeAsync();
        session = await client.OpenSessionAsync();
    }
    else if (ex.ErrorCode == ErrorCode.FrameExpired)
    {
        // Frame-level; skip and continue
    }
}

Pitfalls

• ErrorScope.Connection errors are fatal. Do not retry on the same session.