syntax = 'proto3';
package gateway_protocol;

option java_multiple_files = false;
option java_package = "io.camunda.zeebe.gateway.protocol";
option go_package = "./;pb";

// For a more complete documentation, refer to Zeebe documentation at:
// https://docs.camunda.io/docs/reference/grpc

message StreamActivatedJobsRequest {
  // the job type, as defined in the BPMN process (e.g. <zeebe:taskDefinition
  // type="payment-service" />)
  string type = 1;
  // the name of the worker activating the jobs, mostly used for logging purposes
  string worker = 2;
  // a job returned after this call will not be activated by another call until the
  // timeout (in ms) has been reached
  int64 timeout = 3;
  // a list of variables to fetch as the job variables; if empty, all visible variables at
  // the time of activation for the scope of the job will be returned
  repeated string fetchVariable = 5;
  // a list of identifiers of tenants for which to stream jobs
  repeated string tenantIds = 6;
}

message ActivateJobsRequest {
  // the job type, as defined in the BPMN process (e.g. <zeebe:taskDefinition
  // type="payment-service" />)
  string type = 1;
  // the name of the worker activating the jobs, mostly used for logging purposes
  string worker = 2;
  // a job returned after this call will not be activated by another call until the
  // timeout (in ms) has been reached
  int64 timeout = 3;
  // the maximum jobs to activate by this request
  int32 maxJobsToActivate = 4;
  // a list of variables to fetch as the job variables; if empty, all visible variables at
  // the time of activation for the scope of the job will be returned
  repeated string fetchVariable = 5;
  // The request will be completed when at least one job is activated or after the requestTimeout (in ms).
  // if the requestTimeout = 0, a default timeout is used.
  // if the requestTimeout < 0, long polling is disabled and the request is completed immediately, even when no job is activated.
  int64 requestTimeout = 6;
  // a list of IDs of tenants for which to activate jobs
  repeated string tenantIds = 7;
}

message ActivateJobsResponse {
  // list of activated jobs
  repeated ActivatedJob jobs = 1;
}

message ActivatedJob {
  // the key, a unique identifier for the job
  int64 key = 1;
  // the type of the job (should match what was requested)
  string type = 2;
  // the job's process instance key
  int64 processInstanceKey = 3;
  // the bpmn process ID of the job process definition
  string bpmnProcessId = 4;
  // the version of the job process definition
  int32 processDefinitionVersion = 5;
  // the key of the job process definition
  int64 processDefinitionKey = 6;
  // the associated task element ID
  string elementId = 7;
  // the unique key identifying the associated task, unique within the scope of the
  // process instance
  int64 elementInstanceKey = 8;
  // a set of custom headers defined during modelling; returned as a serialized
  // JSON document
  string customHeaders = 9;
  // the name of the worker which activated this job
  string worker = 10;
  // the amount of retries left to this job (should always be positive)
  int32 retries = 11;
  // when the job can be activated again, sent as a UNIX epoch timestamp
  int64 deadline = 12;
  // JSON document, computed at activation time, consisting of all visible variables to
  // the task scope
  string variables = 13;
  // // the id of the tenant that owns the job
  string tenantId = 14;
}

message CancelProcessInstanceRequest {
  // the process instance key (as, for example, obtained from
  // CreateProcessInstanceResponse)
  int64 processInstanceKey = 1;
}

message CancelProcessInstanceResponse {
}

message CompleteJobRequest {
  // the unique job identifier, as obtained from ActivateJobsResponse
  int64 jobKey = 1;
  // a JSON document representing the variables in the current task scope
  string variables = 2;
}

message CompleteJobResponse {
}

message CreateProcessInstanceRequest {
  // the unique key identifying the process definition (e.g. returned from a process
  // in the DeployProcessResponse message)
  int64 processDefinitionKey = 1;
  // the BPMN process ID of the process definition
  string bpmnProcessId = 2;
  // the version of the process; set to -1 to use the latest version
  int32 version = 3;
  // JSON document that will instantiate the variables for the root variable scope of the
  // process instance; it must be a JSON object, as variables will be mapped in a
  // key-value fashion. e.g. { "a": 1, "b": 2 } will create two variables, named "a" and
  // "b" respectively, with their associated values. [{ "a": 1, "b": 2 }] would not be a
  // valid argument, as the root of the JSON document is an array and not an object.
  string variables = 4;
  // List of start instructions. If empty (default) the process instance
  // will start at the start event. If non-empty the process instance will apply start
  // instructions after it has been created
  repeated ProcessInstanceCreationStartInstruction startInstructions = 5;
  // the tenant id of the process definition
  string tenantId = 6;
}

message ProcessInstanceCreationStartInstruction {

  // future extensions might include
  // - different types of start instructions
  // - ability to set local variables for different flow scopes

  // for now, however, the start instruction is implicitly a
  // "startBeforeElement" instruction

  // element ID
  string elementId = 1;
}

message CreateProcessInstanceResponse {
  // the key of the process definition which was used to create the process instance
  int64 processDefinitionKey = 1;
  // the BPMN process ID of the process definition which was used to create the process
  // instance
  string bpmnProcessId = 2;
  // the version of the process definition which was used to create the process instance
  int32 version = 3;
  // the unique identifier of the created process instance; to be used wherever a request
  // needs a process instance key (e.g. CancelProcessInstanceRequest)
  int64 processInstanceKey = 4;
  // the tenant identifier of the created process instance
  string tenantId = 5;
}

message CreateProcessInstanceWithResultRequest {
  CreateProcessInstanceRequest request = 1;
  // timeout (in ms). the request will be closed if the process is not completed
  // before the requestTimeout.
  // if requestTimeout = 0, uses the generic requestTimeout configured in the gateway.
  int64 requestTimeout = 2;
  // list of names of variables to be included in `CreateProcessInstanceWithResultResponse.variables`
  // if empty, all visible variables in the root scope will be returned.
  repeated string fetchVariables = 3;
}

message CreateProcessInstanceWithResultResponse {
  // the key of the process definition which was used to create the process instance
  int64 processDefinitionKey = 1;
  // the BPMN process ID of the process definition which was used to create the process
  // instance
  string bpmnProcessId = 2;
  // the version of the process definition which was used to create the process instance
  int32 version = 3;
  // the unique identifier of the created process instance; to be used wherever a request
  // needs a process instance key (e.g. CancelProcessInstanceRequest)
  int64 processInstanceKey = 4;
  // JSON document
  // consists of visible variables in the root scope
  string variables = 5;
  // the tenant identifier of the process definition
  string tenantId = 6;
}

message EvaluateDecisionRequest {
  // the unique key identifying the decision to be evaluated (e.g. returned
  // from a decision in the DeployResourceResponse message)
  int64 decisionKey = 1;
  // the ID of the decision to be evaluated
  string decisionId = 2;
  // JSON document that will instantiate the variables for the decision to be
  // evaluated; it must be a JSON object, as variables will be mapped in a
  // key-value fashion, e.g. { "a": 1, "b": 2 } will create two variables,
  // named "a" and "b" respectively, with their associated values.
  // [{ "a": 1, "b": 2 }] would not be a valid argument, as the root of the
  // JSON document is an array and not an object.
  string variables = 3;
  // the tenant identifier of the decision
  string tenantId = 4;
}

message EvaluateDecisionResponse {
  // the unique key identifying the decision which was evaluated (e.g. returned
  // from a decision in the DeployResourceResponse message)
  int64 decisionKey = 1;
  // the ID of the decision which was evaluated
  string decisionId = 2;
  // the name of the decision which was evaluated
  string decisionName = 3;
  // the version of the decision which was evaluated
  int32 decisionVersion = 4;
  // the ID of the decision requirements graph that the decision which was
  // evaluated is part of.
  string decisionRequirementsId = 5;
  // the unique key identifying the decision requirements graph that the
  // decision which was evaluated is part of.
  int64 decisionRequirementsKey = 6;
  // JSON document that will instantiate the result of the decision which was
  // evaluated; it will be a JSON object, as the result output will be mapped
  // in a key-value fashion, e.g. { "a": 1 }.
  string decisionOutput = 7;
  // a list of decisions that were evaluated within the requested decision evaluation
  repeated EvaluatedDecision evaluatedDecisions = 8;
  // an optional string indicating the ID of the decision which
  // failed during evaluation
  string failedDecisionId = 9;
  // an optional message describing why the decision which was evaluated failed
  string failureMessage = 10;
  // the tenant identifier of the evaluated decision
  string tenantId = 11;
}

message EvaluatedDecision {
  // the unique key identifying the decision which was evaluated (e.g. returned
  // from a decision in the DeployResourceResponse message)
  int64 decisionKey = 1;
  // the ID of the decision which was evaluated
  string decisionId = 2;
  // the name of the decision which was evaluated
  string decisionName = 3;
  // the version of the decision which was evaluated
  int32 decisionVersion = 4;
  // the type of the decision which was evaluated
  string decisionType = 5;
  // JSON document that will instantiate the result of the decision which was
  // evaluated; it will be a JSON object, as the result output will be mapped
  // in a key-value fashion, e.g. { "a": 1 }.
  string decisionOutput = 6;
  // the decision rules that matched within this decision evaluation
  repeated MatchedDecisionRule matchedRules = 7;
  // the decision inputs that were evaluated within this decision evaluation
  repeated EvaluatedDecisionInput evaluatedInputs = 8;
  // the tenant identifier of the evaluated decision
  string tenantId = 9;
}

message EvaluatedDecisionInput {
  // the id of the evaluated decision input
  string inputId = 1;
  // the name of the evaluated decision input
  string inputName = 2;
  // the value of the evaluated decision input
  string inputValue = 3;
}

message EvaluatedDecisionOutput {
  // the id of the evaluated decision output
  string outputId = 1;
  // the name of the evaluated decision output
  string outputName = 2;
  // the value of the evaluated decision output
  string outputValue = 3;
}

message MatchedDecisionRule {
  // the id of the matched rule
  string ruleId = 1;
  // the index of the matched rule
  int32 ruleIndex = 2;
  // the evaluated decision outputs
  repeated EvaluatedDecisionOutput evaluatedOutputs = 3;
}

message DeployProcessRequest {
  // since 8, replaced by DeployResourceRequest
  option deprecated = true;
  // List of process resources to deploy
  repeated ProcessRequestObject processes = 1;
}

message ProcessRequestObject {
  // since 8, replaced by Resource
  option deprecated = true;
  // the resource basename, e.g. myProcess.bpmn
  string name = 1;
  // the process definition as a UTF8-encoded string
  bytes definition = 2;
}

message DeployProcessResponse {
  // since 8, replaced by DeployResourceResponse
  option deprecated = true;
  // the unique key identifying the deployment
  int64 key = 1;
  // a list of deployed processes
  repeated ProcessMetadata processes = 2;
}

message DeployResourceRequest {
  // list of resources to deploy
  repeated Resource resources = 1;
  // the tenant id of the resources to deploy
  string tenantId = 2;
}

message Resource {
  // the resource name, e.g. myProcess.bpmn or myDecision.dmn
  string name = 1;
  // the file content as a UTF8-encoded string
  bytes content = 2;
}

message DeployResourceResponse {
  // the unique key identifying the deployment
  int64 key = 1;
  // a list of deployed resources, e.g. processes
  repeated Deployment deployments = 2;
  // the tenant id of the deployed resources
  string tenantId = 3;
}

message Deployment {
  // each deployment has only one metadata
  oneof Metadata {
    // metadata of a deployed process
    ProcessMetadata process = 1;
    // metadata of a deployed decision
    DecisionMetadata decision = 2;
    // metadata of a deployed decision requirements
    DecisionRequirementsMetadata decisionRequirements = 3;
    // metadata of a deployed form
    FormMetadata form = 4;
  }
}

message ProcessMetadata {
  // the bpmn process ID, as parsed during deployment; together with the version forms a
  // unique identifier for a specific process definition
  string bpmnProcessId = 1;
  // the assigned process version
  int32 version = 2;
  // the assigned key, which acts as a unique identifier for this process
  int64 processDefinitionKey = 3;
  // the resource name (see: ProcessRequestObject.name) from which this process was
  // parsed
  string resourceName = 4;
  // the tenant id of the deployed process
  string tenantId = 5;
}

message DecisionMetadata {
  // the dmn decision ID, as parsed during deployment; together with the
  // versions forms a unique identifier for a specific decision
  string dmnDecisionId = 1;
  // the dmn name of the decision, as parsed during deployment
  string dmnDecisionName = 2;
  // the assigned decision version
  int32 version = 3;
  // the assigned decision key, which acts as a unique identifier for this
  // decision
  int64 decisionKey = 4;
  // the dmn ID of the decision requirements graph that this decision is part
  // of, as parsed during deployment
  string dmnDecisionRequirementsId = 5;
  // the assigned key of the decision requirements graph that this decision is
  // part of
  int64 decisionRequirementsKey = 6;
  // the tenant id of the deployed decision
  string tenantId = 7;
}

message DecisionRequirementsMetadata {
  // the dmn decision requirements ID, as parsed during deployment; together
  // with the versions forms a unique identifier for a specific decision
  string dmnDecisionRequirementsId = 1;
  // the dmn name of the decision requirements, as parsed during deployment
  string dmnDecisionRequirementsName = 2;
  // the assigned decision requirements version
  int32 version = 3;
  // the assigned decision requirements key, which acts as a unique identifier
  // for this decision requirements
  int64 decisionRequirementsKey = 4;
  // the resource name (see: Resource.name) from which this decision
  // requirements was parsed
  string resourceName = 5;
  // the tenant id of the deployed decision requirements
  string tenantId = 6;
}

message FormMetadata {
  // the form ID, as parsed during deployment; together with the
  // versions forms a unique identifier for a specific form
  string formId = 1;
  // the assigned form version
  int32 version = 2;
  // the assigned key, which acts as a unique identifier for this form
  int64 formKey = 3;
  // the resource name
  string resourceName = 4;
  // the tenant id of the deployed form
  string tenantId = 5;
}

message FailJobRequest {
  // the unique job identifier, as obtained when activating the job
  int64 jobKey = 1;
  // the amount of retries the job should have left
  int32 retries = 2;
  // an optional message describing why the job failed
  // this is particularly useful if a job runs out of retries and an incident is raised,
  // as it this message can help explain why an incident was raised
  string errorMessage = 3;
  // the backoff timeout (in ms) for the next retry
  int64 retryBackOff = 4;
  // JSON document that will instantiate the variables at the local scope of the
  // job's associated task; it must be a JSON object, as variables will be mapped in a
  // key-value fashion. e.g. { "a": 1, "b": 2 } will create two variables, named "a" and
  // "b" respectively, with their associated values. [{ "a": 1, "b": 2 }] would not be a
  // valid argument, as the root of the JSON document is an array and not an object.
  string variables = 5;
}

message FailJobResponse {
}

message ThrowErrorRequest {
  // the unique job identifier, as obtained when activating the job
  int64 jobKey = 1;
  // the error code that will be matched with an error catch event
  string errorCode = 2;
  // an optional error message that provides additional context
  string errorMessage = 3;
  // JSON document that will instantiate the variables at the local scope of the
  // error catch event that catches the thrown error; it must be a JSON object, as variables will be mapped in a
  // key-value fashion. e.g. { "a": 1, "b": 2 } will create two variables, named "a" and
  // "b" respectively, with their associated values. [{ "a": 1, "b": 2 }] would not be a
  // valid argument, as the root of the JSON document is an array and not an object.
  string variables = 4;
}

message ThrowErrorResponse {
}

message PublishMessageRequest {
  // the name of the message
  string name = 1;
  // the correlation key of the message
  string correlationKey = 2;
  // how long the message should be buffered on the broker, in milliseconds
  int64 timeToLive = 3;
  // the unique ID of the message; can be omitted. only useful to ensure only one message
  // with the given ID will ever be published (during its lifetime)
  string messageId = 4;
  // the message variables as a JSON document; to be valid, the root of the document must be an
  // object, e.g. { "a": "foo" }. [ "foo" ] would not be valid.
  string variables = 5;
  // the tenant id of the message
  string tenantId = 6;
}

message PublishMessageResponse {
  // the unique ID of the message that was published
  int64 key = 1;
  // the tenant id of the message
  string tenantId = 2;
}

message ResolveIncidentRequest {
  // the unique ID of the incident to resolve
  int64 incidentKey = 1;
}

message ResolveIncidentResponse {
}

message TopologyRequest {
}

message TopologyResponse {
  // list of brokers part of this cluster
  repeated BrokerInfo brokers = 1;
  // how many nodes are in the cluster
  int32 clusterSize = 2;
  // how many partitions are spread across the cluster
  int32 partitionsCount = 3;
  // configured replication factor for this cluster
  int32 replicationFactor = 4;
  // gateway version
  string gatewayVersion = 5;
}

message BrokerInfo {
  // unique (within a cluster) node ID for the broker
  int32 nodeId = 1;
  // hostname of the broker
  string host = 2;
  // port for the broker
  int32 port = 3;
  // list of partitions managed or replicated on this broker
  repeated Partition partitions = 4;
  // broker version
  string version = 5;
}

message Partition {
  // Describes the Raft role of the broker for a given partition
  enum PartitionBrokerRole {
    LEADER = 0;
    FOLLOWER = 1;
    INACTIVE = 2;
  }

  // Describes the current health of the partition
  enum PartitionBrokerHealth {
    HEALTHY = 0;
    UNHEALTHY = 1;
    DEAD = 2;
  }

  // the unique ID of this partition
  int32 partitionId = 1;
  // the role of the broker for this partition
  PartitionBrokerRole role = 2;
  // the health of this partition
  PartitionBrokerHealth health = 3;
}

message UpdateJobRetriesRequest {
  // the unique job identifier, as obtained through ActivateJobs
  int64 jobKey = 1;
  // the new amount of retries for the job; must be positive
  int32 retries = 2;
}

message UpdateJobRetriesResponse {
}

message SetVariablesRequest {
  // the unique identifier of a particular element; can be the process instance key (as
  // obtained during instance creation), or a given element, such as a service task (see
  // elementInstanceKey on the job message)
  int64 elementInstanceKey = 1;
  // a JSON serialized document describing variables as key value pairs; the root of the document
  // must be an object
  string variables = 2;
  // if true, the variables will be merged strictly into the local scope (as indicated by
  // elementInstanceKey); this means the variables is not propagated to upper scopes.
  // for example, let's say we have two scopes, '1' and '2', with each having effective variables as:
  // 1 => `{ "foo" : 2 }`, and 2 => `{ "bar" : 1 }`. if we send an update request with
  // elementInstanceKey = 2, variables `{ "foo" : 5 }`, and local is true, then scope 1 will
  // be unchanged, and scope 2 will now be `{ "bar" : 1, "foo" 5 }`. if local was false, however,
  // then scope 1 would be `{ "foo": 5 }`, and scope 2 would be `{ "bar" : 1 }`.
  bool local = 3;
}

message SetVariablesResponse {
  // the unique key of the set variables command
  int64 key = 1;
}

message ModifyProcessInstanceRequest {
  // the key of the process instance that should be modified
  int64 processInstanceKey = 1;
  // instructions describing which elements should be activated in which scopes,
  // and which variables should be created
  repeated ActivateInstruction activateInstructions = 2;
  // instructions describing which elements should be terminated
  repeated TerminateInstruction terminateInstructions = 3;

  message ActivateInstruction {
    // the id of the element that should be activated
    string elementId = 1;
    // the key of the ancestor scope the element instance should be created in;
    // set to -1 to create the new element instance within an existing element
    // instance of the flow scope
    int64 ancestorElementInstanceKey = 2;
    // instructions describing which variables should be created
    repeated VariableInstruction variableInstructions = 3;
  }

  message VariableInstruction {
    // JSON document that will instantiate the variables for the root variable scope of the
    // process instance; it must be a JSON object, as variables will be mapped in a
    // key-value fashion. e.g. { "a": 1, "b": 2 } will create two variables, named "a" and
    // "b" respectively, with their associated values. [{ "a": 1, "b": 2 }] would not be a
    // valid argument, as the root of the JSON document is an array and not an object.
    string variables = 1;
    // the id of the element in which scope the variables should be created;
    // leave empty to create the variables in the global scope of the process instance
    string scopeId = 2;
  }

  message TerminateInstruction {
    // the id of the element that should be terminated
    int64 elementInstanceKey = 1;
  }
}

message ModifyProcessInstanceResponse {

}

message DeleteResourceRequest {
  // The key of the resource that should be deleted. This can either be the key
  // of a process definition, or the key of a decision requirements definition.
  int64 resourceKey = 1;
}

message DeleteResourceResponse {

}

message BroadcastSignalRequest {
  // The name of the signal
  string signalName = 1;

  // the signal variables as a JSON document; to be valid, the root of the document must be an
  // object, e.g. { "a": "foo" }. [ "foo" ] would not be valid.
  string variables = 2;
}

message BroadcastSignalResponse {
  // the unique ID of the signal that was broadcasted.
  int64 key = 1;
}

service Gateway {
  /*
    Iterates through all known partitions round-robin and activates up to the requested
    maximum and streams them back to the client as they are activated.

    Errors:
     INVALID_ARGUMENT:
      - type is blank (empty string, null)
      - worker is blank (empty string, null)
      - timeout less than 1
      - maxJobsToActivate is less than 1
   */
  rpc ActivateJobs (ActivateJobsRequest) returns (stream ActivateJobsResponse) {
  }

  /*
   Registers client to a job stream that will stream jobs back to the client as
   they become activatable.

   Errors:
     INVALID_ARGUMENT:
      - type is blank (empty string, null)
      - timeout less than 1
  */
  rpc StreamActivatedJobs (StreamActivatedJobsRequest) returns (stream ActivatedJob) {
  }

  /*
    Cancels a running process instance

    Errors:
      NOT_FOUND:
        - no process instance exists with the given key
   */
  rpc CancelProcessInstance (CancelProcessInstanceRequest) returns (CancelProcessInstanceResponse) {
  }

  /*
    Completes a job with the given variables, which allows completing the associated service task.

    Errors:
      NOT_FOUND:
        - no job exists with the given job key. Note that since jobs are removed once completed,
          it could be that this job did exist at some point.

      FAILED_PRECONDITION:
        - the job was marked as failed. In that case, the related incident must be resolved before
          the job can be activated again and completed.
   */
  rpc CompleteJob (CompleteJobRequest) returns (CompleteJobResponse) {
  }

  /*
    Creates and starts an instance of the specified process. The process definition to use to
    create the instance can be specified either using its unique key (as returned by
    DeployProcess), or using the BPMN process ID and a version. Pass -1 as the version to use the
    latest deployed version. Note that only processes with none start events can be started through
    this command.

    Errors:
      NOT_FOUND:
        - no process with the given key exists (if processDefinitionKey was given)
        - no process with the given process ID exists (if bpmnProcessId was given but version was -1)
        - no process with the given process ID and version exists (if both bpmnProcessId and version were given)

      FAILED_PRECONDITION:
        - the process definition does not contain a none start event; only processes with none
          start event can be started manually.

      INVALID_ARGUMENT:
        - the given variables argument is not a valid JSON document; it is expected to be a valid
          JSON document where the root node is an object.
   */
  rpc CreateProcessInstance (CreateProcessInstanceRequest) returns (CreateProcessInstanceResponse) {
  }

  /*
    Behaves similarly to `rpc CreateProcessInstance`, except that a successful response is received when the process completes successfully.
  */
  rpc CreateProcessInstanceWithResult (CreateProcessInstanceWithResultRequest) returns (CreateProcessInstanceWithResultResponse) {
  }

  /*
    Evaluates a decision. The decision to evaluate can be specified either by
    using its unique key (as returned by DeployResource), or using the decision
    ID. When using the decision ID, the latest deployed version of the decision
    is used.

    Errors:
      INVALID_ARGUMENT:
        - no decision with the given key exists (if decisionKey was given)
        - no decision with the given decision ID exists (if decisionId was given)
        - both decision ID and decision KEY were provided, or are missing
   */
  rpc EvaluateDecision (EvaluateDecisionRequest) returns (EvaluateDecisionResponse) {
  }

  /*
    Deploys one or more processes to Zeebe. Note that this is an atomic call,
    i.e. either all processes are deployed, or none of them are.

    Errors:
      INVALID_ARGUMENT:
        - no resources given.
        - if at least one resource is invalid. A resource is considered invalid if:
          - the resource data is not deserializable (e.g. detected as BPMN, but it's broken XML)
          - the process is invalid (e.g. an event-based gateway has an outgoing sequence flow to a task)
   */
  rpc DeployProcess (DeployProcessRequest) returns (DeployProcessResponse) {
    // since 8, replaced by DeployResource
    option deprecated = true;
  }

  /*
    Deploys one or more resources (e.g. processes or decision models) to Zeebe.
    Note that this is an atomic call, i.e. either all resources are deployed, or none of them are.

    Errors:
      PERMISSION_DENIED:
        - if a deployment to an unauthorized tenant is performed
      INVALID_ARGUMENT:
        - no resources given.
        - if at least one resource is invalid. A resource is considered invalid if:
          - the content is not deserializable (e.g. detected as BPMN, but it's broken XML)
          - the content is invalid (e.g. an event-based gateway has an outgoing sequence flow to a task)
        - if multi-tenancy is enabled, and:
          - a tenant id is not provided
          - a tenant id with an invalid format is provided
        - if multi-tenancy is disabled and a tenant id is provided
  */
  rpc DeployResource (DeployResourceRequest) returns (DeployResourceResponse) {
  }


  /*
    Marks the job as failed; if the retries argument is positive, then the job will be immediately
    activatable again, and a worker could try again to process it. If it is zero or negative however,
    an incident will be raised, tagged with the given errorMessage, and the job will not be
    activatable until the incident is resolved.

    Errors:
      NOT_FOUND:
        - no job was found with the given key

      FAILED_PRECONDITION:
        - the job was not activated
        - the job is already in a failed state, i.e. ran out of retries
   */
  rpc FailJob (FailJobRequest) returns (FailJobResponse) {
  }

  /*
    Reports a business error (i.e. non-technical) that occurs while processing a job. The error is handled in the process by an error catch event. If there is no error catch event with the specified errorCode then an incident will be raised instead.

    Errors:
      NOT_FOUND:
        - no job was found with the given key

      FAILED_PRECONDITION:
        - the job is not in an activated state
   */
  rpc ThrowError (ThrowErrorRequest) returns (ThrowErrorResponse) {
  }

  /*
    Publishes a single message. Messages are published to specific partitions computed from their
    correlation keys.

    Errors:
      ALREADY_EXISTS:
        - a message with the same ID was previously published (and is still alive)
   */
  rpc PublishMessage (PublishMessageRequest) returns (PublishMessageResponse) {
  }

  /*
    Resolves a given incident. This simply marks the incident as resolved; most likely a call to
    UpdateJobRetries or SetVariables will be necessary to actually resolve the
    problem, following by this call.

    Errors:
      NOT_FOUND:
        - no incident with the given key exists
   */
  rpc ResolveIncident (ResolveIncidentRequest) returns (ResolveIncidentResponse) {
  }

  /*
    Updates all the variables of a particular scope (e.g. process instance, flow element instance)
    from the given JSON document.

    Errors:
      NOT_FOUND:
        - no element with the given elementInstanceKey exists
      INVALID_ARGUMENT:
        - the given variables document is not a valid JSON document; valid documents are expected to
          be JSON documents where the root node is an object.
   */
  rpc SetVariables (SetVariablesRequest) returns (SetVariablesResponse) {
  }

  /*
    Obtains the current topology of the cluster the gateway is part of.
   */
  rpc Topology (TopologyRequest) returns (TopologyResponse) {
  }

  /*
    Updates the number of retries a job has left. This is mostly useful for jobs that have run out of
    retries, should the underlying problem be solved.

    Errors:
      NOT_FOUND:
        - no job exists with the given key

      INVALID_ARGUMENT:
        - retries is not greater than 0
   */
  rpc UpdateJobRetries (UpdateJobRetriesRequest) returns (UpdateJobRetriesResponse) {
  }

  /*
    Modifies the process instance. This is done by activating and/or terminating specific elements of the instance.

    Errors:
      NOT_FOUND:
        - no process instance exists with the given key

      FAILED_PRECONDITION:
        - trying to activate element inside of a multi-instance

      INVALID_ARGUMENT:
        - activating or terminating unknown element
        - ancestor of element for activation doesn't exist
        - scope of variable is unknown
   */
  rpc ModifyProcessInstance (ModifyProcessInstanceRequest) returns (ModifyProcessInstanceResponse) {

  }

  /*
    Deletes a resource from the state. Once a resource has been deleted it cannot
    be recovered. If the resource needs to be available again, a new deployment
    of the resource is required.

    Deleting a process will cancel any running instances of this process
    definition. New instances of a deleted process are created using
    the lastest version that hasn't been deleted. Creating a new
    process instance is impossible when all versions have been
    deleted.

    Deleting a decision requirement definitions could cause incidents in process
    instances referencing these decisions in a business rule task. A decision
    will be evaluated with the latest version that hasn't been deleted. If all
    versions of a decision have been deleted the evaluation is rejected.

    Errors:
      NOT_FOUND:
        - No resource exists with the given key

   */
  rpc DeleteResource (DeleteResourceRequest) returns (DeleteResourceResponse) {

  }

  /*
    Broadcasts a signal.
   */
  rpc BroadcastSignal (BroadcastSignalRequest) returns (BroadcastSignalResponse) {

  }
}