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DCS gRPC is an RPC (Remote Procedure Call) server that allows network clients to interact with a currently runningmission on a DCS server.

Download the latest version of the server from theReleases andextract the zip file into your DCS Server directory.

This is typically found inC:\Users\USERNAME\Saved Games\DCS.openbeta_server.Once extracted you will have aScripts\DCS-gRPC folder, aMods\Tech\DCS-gRPC folder, and aScripts\Hooks\DCS-gRPC.lua file in your server folder. As well as these scripts there will be aDocs/DCS-gRPCfolder containing documentation and aTools/DCS-gRPC folder containing client tools.

To make the gRPC server available in the mission scripting environment, add the following line to yourMissionScripting.lua file that is found by default in the DCS World install folder atC:\Program Files\Eagle Dynamics\DCS World\Scripts\MissionScripting.lua. If you installed the server in another location then look for theScripts\MissionScripting.lua file in there.

Note: The following file is indiff format to highlight the line that has been added.Do note include the+ symbol when you paste into theMissionScripting.lua file.

  --Initialization script for the Mission lua Environment (SSE)  dofile('Scripts/ScriptingSystem.lua')+ dofile(lfs.writedir()..[[Scripts\DCS-gRPC\grpc-mission.lua]])  --Sanitize Mission Scripting environment  --This makes unavailable some unsecure functions.  --Mission downloaded from server to client may contain potentialy harmful lua code that may use these functions.  --You can remove the code below and make availble these functions at your own risk.  local function sanitizeModule(name)    _G[name] = nil    package.loaded[name] = nil  end  do    sanitizeModule('os')    sanitizeModule('io')    sanitizeModule('lfs')    _G['require'] = nil    _G['loadlib'] = nil    _G['package'] = nil  end

There are two ways of running DCS-gRPC. One way allows it to run regardless of what mission is running and the othermeans that DCS-gRPC willonly run if the mission scripting itself enables it.

Create the fileSaved Games\DCS\Config\dcs-grpc.lua and add the line below

autostart=true

As well as this you can set other options in this file. All options and the config file itself are optional – you only have to create the config file and set an option if you want to change any of the default values (the list below shows the default values). The available options are:

-- Whether the `Eval` method is enabled or not.evalEnabled=false-- The host the gRPC listens on (use "0.0.0.0" to listen on all IP addresses of the host).host="127.0.0.1"-- The port to listen on.port=50051-- Whether debug logging is enabled or not.debug=false-- Limit of calls per second that are executed inside of the mission scripting environment.throughputLimit=600-- Whether the integrity check, meant to spot installation issues, is disabled.integrityCheckDisabled=false-- Whether or not authentication is requiredauth.enabled=false-- Authentication tokens table with client names and their tokens for split tokens.auth.tokens= {-- client => clientName, token => Any token. Advice to use UTF-8 only. Length not limited explicitly  {client="SomeClient",token="SomeToken"},   {client="SomeClient2",token="SomeOtherToken"}}-- The default TTS provider to use if a TTS request does not explicitly specify another one.tts.defaultProvider="win"-- Your Azure access key.tts.provider.azure.key="..."-- The Azure region to use (see https://learn.microsoft.com/en-us/azure/cognitive-services/speech-service/regions).tts.provider.azure.region="westeurope"-- The default Azure voice to use (see https://learn.microsoft.com/azure/cognitive-services/speech-service/language-support).tts.provider.azure.defaultVoice="en-US-AriaNeural"-- Your AWS key.tts.provider.aws.key="..."-- Your AWS secret key.tts.provider.aws.secret="..."-- Your AWS region (see https://docs.aws.amazon.com/general/latest/gr/pol.html).tts.provider.aws.region="eu-central-1"-- The default AWS voice to use (see https://docs.aws.amazon.com/polly/latest/dg/voicelist.html).tts.provider.aws.defaultVoice="Brian"-- Your Google Cloud access key.tts.provider.gcloud.key="..."-- The default Google Cloud voice to use (see https://cloud.google.com/text-to-speech/docs/voices).tts.provider.gcloud.defaultVoice="en-GB-Neural2-A"-- The default Windows voice to use (see https://support.microsoft.com/en-us/windows/appendix-a-supported-languages-and-voices-4486e345-7730-53da-fcfe-55cc64300f01).-- Requires at least Windows Server 2019 to work properly.tts.provider.win.defaultVoice="David"-- Your SRS server's address.srs.addr="127.0.0.1:5002"

Once you have done this start the DCS server and skip to the "Confirming that DCS-gRPC is running" section of thisREADME.

Make sure that the fileSaved Games\DCS\Config\dcs-grpc.lua does not exist (Delete if it does).

Add the following code to your mission. This will start the DCS-gRPC server. You can add this code to aDO SCRIPTtrigger in your .miz file or you can add this code to an existing lua file that your mission may be running.

-- Load the gRPC server into the missionGRPC.load()

As well as this you can set other options in the scriptbeforeGRPC.Load() . These are listed below:

-- Whether the `Eval` method is enabled or not.GRPC.evalEnabled=false-- The host the gRPC listens on (use "0.0.0.0" to listen on all IP addresses of the host).GRPC.host='127.0.0.1'-- The port to listen on.GRPC.port=50051-- Whether debug logging is enabled or not.GRPC.debug=false-- Limit of calls per second that are executed inside of the mission scripting environment.GRPC.throughputLimit=600

For example:

GRPC.host='0.0.0.0'GRPC.load()

To confirm that the server is running check the\Logs\dcs.log file and look for entries prefixed withGRPC.You can also check for the present of a\Logs\grpc.log file.

The server will be running on port 50051 by default.

DCS-gRPC provides the following Lua APIs to interact with the server from within Lua.

• GRPC.tts(ssml, frequency[, options]) - Synthesize text (ssml; SSML tags supported) to speech and transmit it over SRS on thefrequency with the following optionaloptions (and their defaults):

  {-- The plain text without any transformations made to it for the purpose of getting it spoken out-- as desired (no SSML tags, no FOUR NINER instead of 49, ...). Even though this field is-- optional, please consider providing it as it can be used to display the spoken text to players-- with hearing impairments.plaintext=null,-- e.g. `= "Hello Pilot"`-- Name of the SRS client.srsClientName="DCS-gRPC",-- The origin of the transmission. Relevant if the SRS server has "Line of-- Sight" and/or "Distance Limit" enabled.position= {lat=0.0,lon=0.0,alt=0.0,-- in meters    },-- The coalition of the transmission. Relevant if the SRS server has "Secure-- Coalition Radios" enabled. Supported values are: `blue` and `red`. Defaults-- to being spectator if not specified.coalition=null,-- TTS provider to be use. Defaults to the one configured in your config or to Windows'-- built-in TTS. Examples:-- `= { aws = {} }` / `= { aws = { voice = "..." } }` enable AWS TTS-- `= { azure = {} }` / `= { azure = { voice = "..." } }` enable Azure TTS-- `= { gcloud = {} }` / `= { gcloud = { voice = "..." } }` enable Google Cloud TTS-- `= { win = {} }` / `= { win = { voice = "..." } }` enable Windows TTSprovider=null,}

DCS-gRPC, as the name implies, uses thegRPC framework to handle communication between clientsand the server. gRPC supports a wide variety of languages which allows you to develop clients in the languages ofyour choice.

In order to develop clients forDCS-gRPC you must be familiar with gRPC concepts so we recommend reading thegRPC documentation for your language.

The gRPC .proto files are available in theDocs/DCS-gRPC folder and also available in the Github repo

If authentication is enabled on the server you will have to addX-API-Key to the metadata/headers.Below are some example on what it could look like in your code.

varclient=newMissionService.MissionServiceClient(channel);Metadatametadata=newMetadata(){{"X-API-Key","<yourKey>"}};varresponse=client.GetScenarioCurrentTime(newGetScenarioCurrentTimeRequest{},headers:metadata,deadline:DateTime.UtcNow.AddSeconds(2));

publicGrpcChannelCreateChannel(stringhost,stringpost,string?apiKey){GrpcChannelOptionsoptions=newGrpcChannelOptions();if(apiKey!=null){CallCredentialscredentials=CallCredentials.FromInterceptor(async(context,metadata)=>{metadata.Add("X-API-Key",apiKey);});options.Credentials=ChannelCredentials.Create(ChannelCredentials.Insecure,credentials);}returnGrpcChannel.ForAddress($"http://{host}:{port}",options);}

The following section is only applicable to people who want to developer the DCS-gRPC server itself.

• Rust>=1.64
• rustfmt (rustup component add rustfmt)

make build

You may need to use the following in powershell

cargo build

Or if you want to use the hot reloading DLL (this is the same asmake build):

cargo build --features hot-reloadcopy target/debug/dcs_grpc.dll target/debug/dcs_grpc_hot_reload.dll

For development:

• update yourMissionScripting.lua to loadgrpc-mission.lua from your local clone, e.g.:

  - dofile(lfs.writedir()..[[Scripts\DCS-gRPC\grpc-mission.lua]])+ dofile([[C:\Development\DCS-gRPC\rust-server\lua\DCS-gRPC\grpc-mission.lua]])

• add customdllPath andluaPath settings to yourSaved Games\DCS\Config\dcs-grpc.lua:

  dllPath=[[C:\Development\DCS-gRPC\rust-server\target\debug\]]luaPath=[[C:\Development\DCS-gRPC\rust-server\lua\DCS-gRPC\]]

• copy the hook script fromlua\Hooks\DCS-gRPC.lua toScripts\Hooks\DCS-gRPC.lua

• setintegrityCheckDisabled = true in yourSaved Games\DCS\Config\dcs-grpc.lua to allow changes to Lua without having to re-compile the dll

• Search for[GRPC] in the DCS logs
• Consult the gRPC Server logs atSaved Games\DCS.openbeta\Logs\gRPC.log

Test the running server viagrpcurl: (Remove the.exe when running on Linux).

grpcurl.exe -plaintext -import-path ./protos -proto ./protos/dcs/dcs.proto -d'{\"text\": \"Works!\", \"display_time\": 10, \"clear_view\": false}' 127.0.0.1:50051 dcs.trigger.v0.TriggerService/OutText

or watch the mission event stream via:

grpcurl.exe -plaintext -import-path ./protos -proto ./protos/dcs/dcs.proto -d'{}' 127.0.0.1:50051 dcs.mission.v0.MissionService/StreamEvents

DCS-gRPC provides the facility to directly run lua code inside the mission scripting environment. This feature ismainly intended for development and is disabled by default. You can enable it via theGRPC settings(SeeSettings section above)

To build and run the repl run the following commands

cargo build -p dcs-grpc-repl# Make sure your DCS mission is runningcargo run -p dcs-grpc-repl

Note that the REPL is hardcoded to connect to localhost on the default port

Once connected you can enter lua code to execute. Prefix the lua withreturn to have the lua code return a value tothe client. For example:

returnGroup.getByName('Aerial-1')= {"id_":1}returnGroup.getByName('Aerial-1'):getName()=Aerial-1

The REPL is also available in the release and can be run by runningTools/DCS-gRPC/repl.exe

This repository is powered by GitHub Actions for the Continuous Integration (CI) services. The same CI checks would betriggered and executed as you push code to your forked repository, and providing early feedback before a maintainerexecutes a manual execution on the pull request.

If you seeLINK : fatal error LNK1104: cannot open file when runningcargo build make sure that there is no running DCS mission as thatlocks the DLL files. Exit the mission (You donot have to exit DCS)then re-run the command before restarting the mission.