Alex,
I have a simpler idea. We already do request id handling in the protocol,
so:
- Client sends a normal request to execute compute task. Request ID is
generated as usual.
- As soon as task is completed, a response is received.
As for cancellation - client can send a new request (with new request ID)
and (in the body) pass the request ID from above
as a task identifier. As a result, there are two responses:
- Cancellation response
- Task response (with proper cancelled status)
That's it, no need to modify the core of the protocol. One request - one
response.
On Mon, Nov 25, 2019 at 6:20 PM Alex Plehanov <plehanov.a...@gmail.com>
wrote:
> Pavel, we need to inform the client when the task is completed, we need the
> ability to cancel the task. I see several ways to implement this:
>
> 1. Сlient sends a request to the server to start a task, server return task
> id in response. Server notifies client when task is completed with a new
> request (from server to client). Client can cancel the task by sending a
> new request with operation type "cancel" and task id. In this case, we
> should implement 2-ways requests.
> 2. Client generates unique task id and sends a request to the server to
> start a task, server don't reply immediately but wait until task is
> completed. Client can cancel task by sending new request with operation
> type "cancel" and task id. In this case, we should decouple request and
> response on the server-side (currently response is sent right after request
> was processed). Also, we can't be sure that task is successfully started on
> a server.
> 3. Client sends a request to the server to start a task, server return id
> in response. Client periodically asks the server about task status. Client
> can cancel the task by sending new request with operation type "cancel" and
> task id. This case brings some overhead to the communication channel.
>
> Personally, I think that the case with 2-ways requests is better, but I'm
> open to any other ideas.
>
> Aleksandr,
>
> Filtering logic for OP_CLUSTER_GROUP_GET_NODE_IDS looks overcomplicated. Do
> we need server-side filtering at all? Wouldn't it be better to send basic
> info (ids, order, flags) for all nodes (there is relatively small amount of
> data) and extended info (attributes) for selected list of nodes? In this
> case, we can do basic node filtration on client-side (forClients(),
> forServers(), forNodeIds(), forOthers(), etc).
>
> Do you use standard ClusterNode serialization? There are also metrics
> serialized with ClusterNode, do we need it on thin client? There are other
> interfaces exist to show metrics, I think it's redundant to export metrics
> to thin clients too.
>
> What do you think?
>
>
>
>
> пт, 22 нояб. 2019 г. в 20:15, Aleksandr Shapkin <lexw...@gmail.com>:
>
> > Alex,
> >
> >
> >
> > I think you can create a new IEP page and I will fill it with the Cluster
> > API details.
> >
> >
> >
> > In short, I’ve introduced several new codes:
> >
> >
> >
> > Cluster API is pretty straightforward:
> >
> >
> >
> > OP_CLUSTER_IS_ACTIVE = 5000
> >
> > OP_CLUSTER_CHANGE_STATE = 5001
> >
> > OP_CLUSTER_CHANGE_WAL_STATE = 5002
> >
> > OP_CLUSTER_GET_WAL_STATE = 5003
> >
> >
> >
> > Cluster group codes:
> >
> >
> >
> > OP_CLUSTER_GROUP_GET_NODE_IDS = 5100
> >
> > OP_CLUSTER_GROUP_GET_NODE_INFO = 5101
> >
> >
> >
> > The underlying implementation is based on the thick client logic.
> >
> >
> >
> > For every request, we provide a known topology version and if it has
> > changed,
> >
> > a client updates it firstly and then re-sends the filtering request.
> >
> >
> >
> > Alongside the topVer a client sends a serialized nodes projection object
> >
> > that could be considered as a code to value mapping.
> >
> > Consider: [{Code = 1, Value= [“DotNet”, “MyAttribute”}, {Code=2,
> Value=1}]
> >
> > Where “1” stands for Attribute filtering and “2” – serverNodesOnly flag.
> >
> >
> >
> > As a result of request processing, a server sends nodeId UUIDs and a
> > current topVer.
> >
> >
> >
> > When a client obtains nodeIds, it can perform a NODE_INFO call to get a
> >
> > serialized ClusterNode object. In addition there should be a different
> API
> >
> > method for accessing/updating node metrics.
> >
> > чт, 21 нояб. 2019 г. в 12:32, Sergey Kozlov <skoz...@gridgain.com>:
> >
> > > Hi Pavel
> > >
> > > On Thu, Nov 21, 2019 at 11:30 AM Pavel Tupitsyn <ptupit...@apache.org>
> > > wrote:
> > >
> > > > 1. I believe that Cluster operations for Thin Client protocol are
> > already
> > > > in the works
> > > > by Alexandr Shapkin. Can't find the ticket though.
> > > > Alexandr, can you please confirm and attach the ticket number?
> > > >
> > > > 2. Proposed changes will work only for Java tasks that are already
> > > deployed
> > > > on server nodes.
> > > > This is mostly useless for other thin clients we have (Python, PHP,
> > .NET,
> > > > C++).
> > > >
> > >
> > > I don't guess so. The task (execution) is a way to implement own layer
> > for
> > > the thin client application.
> > >
> > >
> > > > We should think of a way to make this useful for all clients.
> > > > For example, we may allow sending tasks in some scripting language
> like
> > > > Javascript.
> > > > Thoughts?
> > > >
> > >
> > > The arbitrary code execution from a remote client must be protected
> > > from malicious code.
> > > I don't know how it could be designed but without that we open the hole
> > to
> > > kill cluster.
> > >
> > >
> > > >
> > > > On Thu, Nov 21, 2019 at 11:21 AM Sergey Kozlov <skoz...@gridgain.com
> >
> > > > wrote:
> > > >
> > > > > Hi Alex
> > > > >
> > > > > The idea is great. But I have some concerns that probably should be
> > > taken
> > > > > into account for design:
> > > > >
> > > > > 1. We need to have the ability to stop a task execution, smth
> like
> > > > > OP_COMPUTE_CANCEL_TASK operation (client to server)
> > > > > 2. What's about task execution timeout? It may help to the
> cluster
> > > > > survival for buggy tasks
> > > > > 3. Ignite doesn't have roles/authorization functionality for
> now.
> > > But
> > > > a
> > > > > task is the risky operation for cluster (for security reasons).
> > > Could
> > > > we
> > > > > add for Ignite configuration new options:
> > > > > - Explicit turning on for compute task support for thin
> > protocol
> > > > > (disabled by default) for whole cluster
> > > > > - Explicit turning on for compute task support for a node
> > > > > - The list of task names (classes) allowed to execute by thin
> > > > client.
> > > > > 4. Support the labeling for task that may help to investigate
> > issues
> > > > on
> > > > > cluster (the idea from IEP-34 [1])
> > > > >
> > > > > 1.
> > > > >
> > > > >
> > > >
> > >
> >
> https://cwiki.apache.org/confluence/display/IGNITE/IEP-34+Thin+client%3A+transactions+support
> > > > >
> > > > >
> > > > >
> > > > > On Thu, Nov 21, 2019 at 10:58 AM 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?
> > > > > >
> > > > >
> > > > >
> > > > > --
> > > > > Sergey Kozlov
> > > > > GridGain Systems
> > > > > www.gridgain.com
> > > > >
> > > >
> > >
> > >
> > > --
> > > Sergey Kozlov
> > > GridGain Systems
> > > www.gridgain.com
> > >
> >
> >
> > --
> > Alex.
> >
>
