Denis, the primary motivation is to enable execution of deployed to server java tasks from thin clients (java and other languages).
пт, 22 нояб. 2019 г. в 00:03, Denis Magda <dma...@apache.org>: > Alex, what is the primary motivation for this improvement? Are you looking > to enable the compute APIs for languages different from Java? > > - > Denis > > > On Wed, Nov 20, 2019 at 11:58 PM Alex Plehanov <plehanov.a...@gmail.com> > wrote: > > > Hello, Igniters! > > > > I have plans to start implementation of Compute interface for Ignite thin > > client and want to discuss features that should be implemented. > > > > We already have Compute implementation for binary-rest clients > > (GridClientCompute), which have the following functionality: > > - Filtering cluster nodes (projection) for compute > > - Executing task by the name > > > > I think we can implement this functionality in a thin client as well. > > > > First of all, we need some operation types to request a list of all > > available nodes and probably node attributes (by a list of nodes). Node > > attributes will be helpful if we will decide to implement analog of > > ClusterGroup#forAttribute or ClusterGroup#forePredicate methods in the > thin > > client. Perhaps they can be requested lazily. > > > > From the protocol point of view there will be two new operations: > > > > OP_CLUSTER_GET_NODES > > Request: empty > > Response: long topologyVersion, int minorTopologyVersion, int nodesCount, > > for each node set of node fields (UUID nodeId, Object or String > > consistentId, long order, etc) > > > > OP_CLUSTER_GET_NODE_ATTRIBUTES > > Request: int nodesCount, for each node: UUID nodeId > > Response: int nodesCount, for each node: int attributesCount, for each > node > > attribute: String name, Object value > > > > To execute tasks we need something like these methods in the client API: > > Object execute(String task, Object arg) > > Future<Object> executeAsync(String task, Object arg) > > Object affinityExecute(String task, String cache, Object key, Object arg) > > Future<Object> affinityExecuteAsync(String task, String cache, Object > key, > > Object arg) > > > > Which can be mapped to protocol operations: > > > > OP_COMPUTE_EXECUTE_TASK > > Request: UUID nodeId, String taskName, Object arg > > Response: Object result > > > > OP_COMPUTE_EXECUTE_TASK_AFFINITY > > Request: String cacheName, Object key, String taskName, Object arg > > Response: Object result > > > > The second operation is needed because we sometimes can't calculate and > > connect to affinity node on the client-side (affinity awareness can be > > disabled, custom affinity function can be used or there can be no > > connection between client and affinity node), but we can make best effort > > to send request to target node if affinity awareness is enabled. > > > > Currently, on the server-side requests always processed synchronously and > > responses are sent right after request was processed. To execute long > tasks > > async we should whether change this logic or introduce some kind two-way > > communication between client and server (now only one-way requests from > > client to server are allowed). > > > > Two-way communication can also be useful in the future if we will send > some > > server-side generated events to clients. > > > > In case of two-way communication there can be new operations introduced: > > > > OP_COMPUTE_EXECUTE_TASK (from client to server) > > Request: UUID nodeId, String taskName, Object arg > > Response: long taskId > > > > OP_COMPUTE_TASK_FINISHED (from server to client) > > Request: taskId, Object result > > Response: empty > > > > The same for affinity requests. > > > > Also, we can implement not only execute task operation, but some other > > operations from IgniteCompute (broadcast, run, call), but it will be > useful > > only for java thin client. And even with java thin client we should > whether > > implement peer-class-loading for thin clients (this also requires two-way > > client-server communication) or put classes with executed closures to the > > server locally. > > > > What do you think about proposed protocol changes? > > Do we need two-way requests between client and server? > > Do we need support of compute methods other than "execute task"? > > What do you think about peer-class-loading for thin clients? > > >
