/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

syntax = "proto3";

option java_multiple_files = true;
option java_package = "org.apache.skywalking.apm.network.language.agent.v3";
option csharp_namespace = "SkyWalking.NetworkProtocol.V3";
option go_package = "skywalking/network/language/agent/v3";

import "common/Common.proto";

// Define a trace segment report service.
// All language agents or any trace collecting component, could use this service to send span collection to the SkyWalking OAP backend.
service TraceSegmentReportService {
    // Recommended trace segment report channel.
    // gRPC streaming provides better performance.
    // All language agents should choose this.
    rpc collect (stream SegmentObject) returns (Commands) {
    }

    // An alternative for trace report by using gRPC unary
    // This is provided for some 3rd-party integration, if and only if they prefer the unary mode somehow.
    // The performance of SkyWalking OAP server would be very similar with streaming report,
    // the performance of the network and client side are affected
    rpc collectInSync (SegmentCollection) returns (Commands) {
    }
}

// The segment is a collection of spans. It includes all collected spans in a simple one request context, such as a HTTP request process.
//
// We recommend the agent/SDK report all tracked data of one request once for all, such as, 
// typically, such as in Java, one segment represent all tracked operations(spans) of one request context in the same thread.
// At the same time, in some language there is not a clear concept like golang, it could represent all tracked operations of one request context.
message SegmentObject {
    // A string id represents the whole trace.
    string traceId = 1;
    // A unique id represents this segment. Other segments could use this id to reference as a child segment.
    string traceSegmentId = 2;
    // Span collections included in this segment.
    repeated SpanObject spans = 3;
    // **Service**. Represents a set/group of workloads which provide the same behaviours for incoming requests.
    // 
    // The logic name represents the service. This would show as a separate node in the topology.
    // The metrics analyzed from the spans, would be aggregated for this entity as the service level.
    string service = 4;
    // **Service Instance**. Each individual workload in the Service group is known as an instance. Like `pods` in Kubernetes, it 
    // doesn't need to be a single OS process, however, if you are using instrument agents, an instance is actually a real OS process.
    //
    // The logic name represents the service instance. This would show as a separate node in the instance relationship.
    // The metrics analyzed from the spans, would be aggregated for this entity as the service instance level.
    string serviceInstance = 5;
    // Whether the segment includes all tracked spans.
    // In the production environment tracked, some tasks could include too many spans for one request context, such as a batch update for a cache, or an async job.
    // The agent/SDK could optimize or ignore some tracked spans for better performance. 
    // In this case, the value should be flagged as TRUE.
    bool isSizeLimited = 6;
}

// Segment reference represents the link between two existing segment.
message SegmentReference {
    // Represent the reference type. It could be across thread or across process.
    // Across process means there is a downstream RPC call for this.
    // Typically, refType == CrossProcess means SpanObject#spanType = entry.
    RefType refType = 1;
    // A string id represents the whole trace.
    string traceId = 2;
    // Another segment id as the parent.
    string parentTraceSegmentId = 3;
    // The span id in the parent trace segment.
    int32 parentSpanId = 4;
    // The service logic name of the parent segment. 
    // If refType == CrossThread, this name is as same as the trace segment.
    string parentService = 5;
    // The service logic name instance of the parent segment. 
    // If refType == CrossThread, this name is as same as the trace segment.
    string parentServiceInstance = 6;
    // The endpoint name of the parent segment.
    // **Endpoint**. A path in a service for incoming requests, such as an HTTP URI path or a gRPC service class + method signature.
    // In a trace segment, the endpoint name is the name of first entry span.
    string parentEndpoint = 7;
    // The network address, including ip/hostname and port, which is used in the client side.
    // Such as Client --> use 127.0.11.8:913 -> Server
    // then, in the reference of entry span reported by Server, the value of this field is 127.0.11.8:913.
    // This plays the important role in the SkyWalking STAM(Streaming Topology Analysis Method)
    // For more details, read https://wu-sheng.github.io/STAM/
    string networkAddressUsedAtPeer = 8;
}

// Span represents a execution unit in the system, with duration and many other attributes.
// Span could be a method, a RPC, MQ message produce or consume.
// In the practice, the span should be added when it is really necessary, to avoid payload overhead.
// We recommend to creating spans in across process(client/server of RPC/MQ) and across thread cases only.
message SpanObject {
    // The number id of the span. Should be unique in the whole segment.
    // Starting at 0.
    int32 spanId = 1;
    // The number id of the parent span in the whole segment.
    // -1 represents no parent span.
    // Also, be known as the root/first span of the segment.
    int32 parentSpanId = 2;
    // Start timestamp in milliseconds of this span,
    // measured between the current time and midnight, January 1, 1970 UTC.
    int64 startTime = 3;
    // End timestamp in milliseconds of this span,
    // measured between the current time and midnight, January 1, 1970 UTC.
    int64 endTime = 4;
    // <Optional> 
    // In the across thread and across process, these references targeting the parent segments.
    // The references usually have only one element, but in batch consumer case, such as in MQ or async batch process, it could be multiple.
    repeated SegmentReference refs = 5;
    // A logic name represents this span.
    //
    // We don't recommend to include the parameter, such as HTTP request parameters, as a part of the operation, especially this is the name of the entry span.
    // All statistic for the endpoints are aggregated base on this name. Those parameters should be added in the tags if necessary.
    // If in some cases, it have to be a part of the operation name,
    // users should use the Group Parameterized Endpoints capability at the backend to get the meaningful metrics. 
    // Read https://github.com/apache/skywalking/blob/master/docs/en/setup/backend/endpoint-grouping-rules.md
    string operationName = 6;
    // Remote address of the peer in RPC/MQ case.
    // This is required when spanType = Exit, as it is a part of the SkyWalking STAM(Streaming Topology Analysis Method).
    // For more details, read https://wu-sheng.github.io/STAM/
    string peer = 7;
    // Span type represents the role in the RPC context.
    SpanType spanType = 8;
    // Span layer represent the component tech stack, related to the network tech.
    SpanLayer spanLayer = 9;
    // Component id is a predefinited number id in the SkyWalking.
    // It represents the framework, tech stack used by this tracked span, such as Spring.
    // All IDs are defined in the https://github.com/apache/skywalking/blob/master/oap-server/server-bootstrap/src/main/resources/component-libraries.yml
    // Send a pull request if you want to add languages, components or mapping defintions,
    // all public components could be accepted.
    // Follow this doc for more details, https://github.com/apache/skywalking/blob/master/docs/en/guides/Component-library-settings.md
    int32 componentId = 10;
    // The status of the span. False means the tracked execution ends in the unexpected status.
    // This affects the successful rate statistic in the backend.
    // Exception or error code happened in the tracked process doesn't mean isError == true, the implementations of agent plugin and tracing SDK make the final decision.
    bool isError = 11;
    // String key, String value pair.
    // Tags provides more informance, includes parameters.
    //
    // In the OAP backend analysis, some special tag or tag combination could provide other advanced features.
    // https://github.com/apache/skywalking/blob/master/docs/en/guides/Java-Plugin-Development-Guide.md#special-span-tags
    repeated KeyStringValuePair tags = 12;
    // String key, String value pair with an accurate timestamp.
    // Logging some events happening in the context of the span duration.
    repeated Log logs = 13;
    // Force the backend don't do analysis, if the value is TRUE.
    // The backend has its own configurations to follow or override this.
    // 
    // Use this mostly because the agent/SDK could know more context of the service role.
    bool skipAnalysis = 14;
}

message Log {
    // The timestamp in milliseconds of this event.,
    // measured between the current time and midnight, January 1, 1970 UTC.
    int64 time = 1;
    // String key, String value pair.
    repeated KeyStringValuePair data = 2;
}

// Map to the type of span
enum SpanType {
    // Server side of RPC. Consumer side of MQ.
    Entry = 0;
    // Client side of RPC. Producer side of MQ.
    Exit = 1;
    // A common local code execution.
    Local = 2;
}

// A ID could be represented by multiple string sections.
message ID {
    repeated string id = 1;
}

// Type of the reference
enum RefType {
    // Map to the reference targeting the segment in another OS process.
    CrossProcess = 0;
    // Map to the reference targeting the segment in the same process of the current one, just across thread.
    // This is only used when the coding language has the thread concept. 
    CrossThread = 1;
}

// Map to the layer of span
enum SpanLayer {
    // Unknown layer. Could be anything.
    Unknown = 0;
    // A database layer, used in tracing the database client component.
    Database = 1;
    // A RPC layer, used in both client and server sides of RPC component.
    RPCFramework = 2;
    // HTTP is a more specific RPCFramework.
    Http = 3;
    // A MQ layer, used in both producer and consuer sides of the MQ component.
    MQ = 4;
    // A cache layer, used in tracing the cache client component.
    Cache = 5;
}

// The segment collections for trace report in batch and sync mode.
message SegmentCollection {
    repeated SegmentObject segments = 1;
}