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From Alex Plehanov <plehanov.a...@gmail.com>
Subject Re: Thin client: compute support
Date Mon, 25 Nov 2019 15:19:43 GMT
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 <lexwert@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 <skozlov@gridgain.com>:
>
> > Hi Pavel
> >
> > On Thu, Nov 21, 2019 at 11:30 AM Pavel Tupitsyn <ptupitsyn@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 <skozlov@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.alex@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.
>

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