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IDIEP-50
Author

 Pavel Tupitsyn

Sponsor
 Pavel Tupitsyn
Created

 

Status

Status
colourGreen
titleDRAFTCOMPLETED


Table of Contents

Motivation

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  • Cache update listener: while query is active, client receives events. Server → Client notification mechanism already exists for that (see IEP-42 Thin client: compute supportClient Compute).
  • (Optional) Remote filter(Optional) Initial query: Sql or Scan

Remote Filter is a BinaryObject:

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ContinuousQueryWithTransformer is out of scope: it is a separate class, and should have a separate client operation.

Initial Query functionality is excluded intentionally, it does not bring value due to lack of guarantees - see dev list threads linked below.

Operation codes

Name

Code

OP_QUERY_CONTINUOUS2006

OP_QUERY_CONTINUOUS_EVENT_NOTIFICATION

2007

OP_QUERY_CONTINUOUS starts the query.

Existing OP_RESOURCE_CLOSE should be used to stop stops the continuous query using the id provided in the OP_QUERY_CONTINUOUS response message.

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filterPlatform (when filter is not null)pageSize

when initialQueryType == 2 (SQL)

Request
intcacheId
byteflags: standard cache flags, see ClientCacheRequest. Only KEEP_BINARY is applicable to Continuous Query. When KEEP_BINARY is set, the filter should receive key/val in binary form.
intbufferSize (see AbstractContinuousQuery, default 1)
longtimeInterval (see AbstractContinuousQuery, default 0)
boolincludeExpired (see AbstractContinuousQuery, default false)
BinaryObjectfilter
bytefilterPlatform (see ClientCacheScanQueryRequest, 1= Java, 2 = .NET) (when filter is not null)
byteinitialQueryType (0 = NONE, 1 = SQL, 2 = SCAN)
initialQuery (when initialQueryType > 0)when initialQueryType == 1 (SCAN)
BinaryObjectfilter
byteint
intpartition (-1 for no partition)
boollocal
stringschema
intpageSize
stringsql
intargument count
n * Objectarguments
booldistributed joins
boollocal
boolenforce join order
boolcolocated
boollazy
longtimeout, in milliseconds


Response
longcontinuousQueryId - used to retrieve initial query data and stop the query with OP_RESOURCE_CLOSE
intcolumnCount (when initial query is SQL)
n * stringcolumn names (when initial query is SQL)

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RESOURCE_CLOSE

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Note: AbstractContinuousQuery.autoUnsubscribe should be always true for thin client continuous queries.

As a result of OP_QUERY_CONTINUOUS and until OP_RESOURCE_CLOSE is called, client should expect OP_QUERY_CONTINUOUS_EVENT_NOTIFICATION messages from the server:

OP_QUERY_CONTINUOUS_EVENT_NOTIFICATION message format

intevent count
n * CacheEntryEvent


BinaryObjectkey
BinaryObjectold value
BinaryObjectvalue
byteevent type (0 = CREATED, 1 = UPDATED, 2 = REMOVED, 3 = EXPIRED)


Risks & Assumptions

  • Flow control & backpressure: We assume no special flow control and rely on GridNioServer to handle "slow client, fast server" scenario.
  • Fault tolerance: Initial implementation does not provide failover in case when server node that holds the query goes down or client connection fails. It is up to specific client implementation to notify user code about the connection loss (for example, by providing special CacheEntryEvent instance that throws an exception from all members).

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Tickets


Jira
serverASF JIRA
columnskey,summary,type,created,updated,due,assignee,reporter,priority,status,resolution
maximumIssues20
jqlQuerylabels=iep-50
serverId5aa69414-a9e9-3523-82ec-879b028fb15bkeyIGNITE-13148