How to create <service>_client.erl ?

[minghu6]

I have read the README about https://github.com/tsloughter/grpcbox#using-a-service-client. However, When I run rebar3 gprc gen on the root of my project, it only creates*_pb.erl and*_bhvr.erl. So, there is any other steps to generate <service>_client.erl ?

[tsloughter]

Ah, sorry, I hadn't merged the plugin client branch to master.

I've pushed to master now so upgrading the plugin should result in the client being generated.

[minghu6]

en, I edit rebar.config {grpcbox_plugin, {git, "https://github.com/tsloughter/grpcbox.git", {branch, "master"}}}, unlock and recompile, but it seems that no new version to upgrade?

[tsloughter]

It is {grpcbox_plugin, {git, "https://github.com/tsloughter/grpcbox_plugin.git", {branch, "master"}}}

But also plugins aren't locked, you want rebar3 plugins upgrade grpcbox_plugin or just blow away the _build/default/plugins dir.

[minghu6]

When I run rebar3 plugins upgrade grpcbox_plugin, it prints:

===> Fetching chatterbox ({git,
                                  "https://github.com/tsloughter/chatterbox",
                                  {ref,
                                   "0d8c06bf23ec65a6a500337d25e856b850a7d711"}})

But where is commit 0d8c06bf23ec65a6a500337d25e856b850a7d711?

[tsloughter]

No reason it shouldn't find that, it is definitely there: https://github.com/tsloughter/chatterbox/commit/0d8c06bf23ec65a6a500337d25e856b850a7d711

[tsloughter]

Because I haven't got the chatterbox changes merged to master and pushed to hex this was in a sort of state of flux. Once that is done I'll publish new releases known to work together.

Though from master for both grpcbox and the plugin they should work together.

[minghu6]

Yes, i only seach the master branch...

After upgrade the plugin, rebar3 grpc gen did generate *_client.erl file!

but another issue is

===> Compiling src/hellostreamingworld_multi_greeter_client.erl failed
src/hellostreamingworld_multi_greeter_client.erl:13: can't find include file "grpcbox.hrl"

when rebar3 compile

(I can found this hrl file in the ./_build/default/lib/grpcbox/include)

[minghu6]

If i skip the can't find "grpcbox.hrl" file issue (by copy the grpcbox.hrl into the project's include folder)

I run rebar3 shell

1> hellostreamingworld_multi_greeter_client:say_hello(ctx:new(), #{name => "Woc", num_greetings => 3}, #{}).

** exception error: bad argument
     in function  ets:lookup/2
        called as ets:lookup(gproc,{{p,l,{gproc_pool,default_channel}},shared})
     in call from gproc:get_value1/2 (/home/johnzhuang/coding/erl-repos/myapp/_build/default/lib/gproc/src/gproc.erl, line 1602)
     in call from gproc:get_value/2 (/home/johnzhuang/coding/erl-repos/myapp/_build/default/lib/gproc/src/gproc.erl, line 1584)
     in call from gproc_pool:pick_worker/1 (/home/johnzhuang/coding/erl-repos/myapp/_build/default/lib/gproc/src/gproc_pool.erl, line 314)
     in call from grpcbox_channel:pick/2 (/home/johnzhuang/coding/erl-repos/myapp/_build/default/lib/grpcbox/src/grpcbox_channel.erl, line 47)
     in call from grpcbox_client:stream/5 (/home/johnzhuang/coding/erl-repos/myapp/_build/default/lib/grpcbox/src/grpcbox_client.erl, line 121)

hellostreamingworld.proto

syntax = "proto3";

package hellostreamingworld;

// The greeting service definition.
service MultiGreeter {
  // Sends multiple greetings
  rpc sayHello (HelloRequest) returns (stream HelloReply) {}
}

// The request message containing the user's name and how many greetings
// they want.
message HelloRequest {
  string name = 1;
  string num_greetings = 2;
}

// A response message containing a greeting
message HelloReply {
  string message = 1;
}

And there is a sys.config in config folder of project, with

[
  { myapp, [{client, #{channels => [{default_channel, [{http, "localhost", 50051, []}], #{}}]}}]}
].

What's the problem ?

[tsloughter]

Hm, that error (I should make it better and will) is that the channel isn't found.

Are you sure the server is listening?

[minghu6]

Yes, the server is listening, I am using google grpc python demo server, and I have tested it with grpc_client.

Maybe I have mistake on setting channel? If I set channel manually like below helloworld_greeter_client:say_hello(ctx:new(), #{name => "Joe"}, #{channel => [{http, "localhost", 50051, []}]}). That's OK?

[tsloughter]

Na, the channel needs to be started and is references an atom that represents the channel's pool and is used to pick a subchannel:

gproc_pool:pick_worker(Name)

Though first i'd verify that in the shell application:get_env(grpcbox, client) returns what you'd expect based on your config.

Maybe your config isn't being used? Or grpcbox isn't being started when you run shell? You can do rebar3 shell --config config/sys.config or set that in your rebar.config under the {shell, [...]}

[minghu6]

Very interesting, when I first application:get_env(grpcbox, client), it returns undefined. Then I add grpcbox onto the apps, now my

rebar.config

{erl_opts, [debug_info]}.
{deps, [{grpcbox, {git, "https://github.com/tsloughter/grpcbox.git", {branch, "master"}}}]}.

{grpc, [{protos, "priv/protos"},
        {gpb_opts, [{module_name_suffix, "_pb"}]}]}.

{plugins, [{grpcbox_plugin, {git, "https://github.com/tsloughter/grpcbox_plugin.git", {branch, "master"}}}]}.
{shell, [
    {config, "config/sys.config"},
    {apps, [myapp, grpcbox]}
]}.

But when i re-run application:get_env(grpcbox, client) (in rebar3 shell --config config/sys.config), It returns {ok,#{channels => []}}

config/sys.cionfig

[
  { myapp, 
    [
      {client, #{channels => [{default_channel, [{http, "localhost", 50051, []}], #{}}]}},
      {pool_opts, #{size => 10}},
      {grpc_opts, #{service_protos => [helloworld_pb, hellostreamingworld_pb]}}
    ]
  }
].

It seems like not load client config, and why

[tsloughter]

Oooh, I should have noticed this the first time you posted your sys config.

You need to put the options for grpc under grpcbox, so:

[
  { grpcbox, 
    [
      {client, #{channels => [{default_channel, [{http, "localhost", 50051, []}], #{}}]}},
      {pool_opts, #{size => 10}},
      {grpc_opts, #{service_protos => [helloworld_pb, hellostreamingworld_pb]}}
    ]
  }
].

[minghu6]

That's it! I mistakenly think the options is for myapp... After recorrected it, I can get channel config, and get response from grpc server. Thank you very much!

[tsloughter]

Great!