| Internet-Draft | DAMC | August 2023 |
| Li, et al. | Expires 10 February 2024 | [Page] |
This draft defines a new communication architecture, called Distributed Architecture for Microservices Communication (DAMC). It includes multiple aspects of microservice communication, such as service registration, service discovery, service routing, service scheduling, and more , Which to achieve all the essential functionalities provided by current centralized service networks. The purpose of this draft is to combine the Information-Centric Networking (ICN) concept to enhance the overall performance, scalability and reliability of microservices communication. The DAMC architecture provides a powerful framework for managing the complex communication requirements of distributed microservices, ensuring integrity, security and efficient resource utilization.¶
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The microservices architecture [Microservices] is a modern software development approach. By breaking down applications into smaller, independent service units, it enhances flexibility, maintainability, and scalability. It is a paradigm for building complex software applications by breaking them down into small, independent, and loosely coupled service units, known as microservices. Each microservice focuses on a specific business capability and operates as an autonomous unit with its own database and communication mechanism.¶
In recent years, the rapid adoption of microservices architecture has revolutionized the development and deployment of complex software systems. However, as the number of microservices grows and the communication between them becomes more intricate, traditional centralized service-oriented network architectures [SOA] face challenges in meeting the demands of large-scale and distributed microservices deployments. To address these challenges, the concept of Information-Centric Networking (ICN)[ICN] has emerged as a promising paradigm that focuses on the content itself rather than the location of the services.¶
In current microservices communication scenario shown in Figure 1. The essential functionalities for microservice colmmunication, including service registration, service discovery, service scheduling, and service measurement, are typically implemented through the deployment of proxies within a shared addressable unit known as a Pod alongside microservices. The interconnection between these proxies forms a new foundational communication infrastructure known as the Service Mesh [ServiceMesh].¶
All communication between microservices at the forwarding level is facilitated through these proxies.The implementation process of the key functions of the centralized control service-oriented network architecture is as follows:¶
1) Service registration¶
Microservices register with their corresponding proxies, which in turn register with the centralized control center.¶
2) Service discovery¶
The centralized control center distributes relevant service registration information to each proxy, enabling the synchronization of microservice information.¶
3) Service measurement¶
Proxies proactively conduct quality probing towards target microservices and report relevant information to the control center.¶
4) Service scheduling¶
The centralized control center distributes relevant service scheduling policies to each proxy. Each proxy analyzes the received microservice communication demands and performs scheduling based on the policies and the communication requirements of the microservices.¶
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| +-------------------------------------------------------+ |
| | | |
| | +---------------+ +---------------+ | |
| | | +---------+ | | +---------+ | | |
| | Data | |Service A| | | |Service B| | | |
| | Plane| +---------+ | Mesh traffic| +---------+ | | |
| ---------> | | | |-----------> | | | |---------> |
|Ingress| | +---------+ | | +---------+ | | Egress |
|traffic| | | Proxy | | | | Proxy | | | traffic |
| | | +---------+ | | +---------+ | | |
| | +---------------+ +---------------+ | |
| | | Discovery | | |
| | | Configuration | | |
| | |_________Certificates_______| | |
| | | | |
| | | | |
| | Control Plane | | |
| | +----------------------------+ | |
| | | Controller | | |
| | +----------------------------+ | |
| | | |
| +-------------------------------------------------------+ |
| |
+-------------------------------------------------------------------------+
Figure 1 The architecture of current centralized service-based network
¶
To sum up, the centralized service-oriented network architecture is difficult to meet the communication needs of large-scale and complex microservices, and there are performance, scalability, and reliability bottlenecks.¶
1) Performance bottlenecks¶
In centralized architectures, the central control point becomes a potential performance bottleneck as it handles all communication traffic. Routing traffic through a central controller introduces increased latency, which can adversely affect the overall system performance. As the number of microservices and communication volume grow, the centralized control point may face challenges in efficiently managing the increasing traffic load.¶
2) Poor scalability¶
Scaling a central control point becomes increasingly complex as the system grows, as it requires substantial resources and careful management. Consequently, the centralized approach may struggle to handle the dynamic nature of microservices and their evolving communication patterns.¶
3) Reliability issues¶
If the central control component experiences downtime or malfunctions, it can disrupt the entire communication flow among microservices. This vulnerability can result in service disruptions and decreased availability of the system as a whole.¶
Based on the above, the goal of this draft is to propose an architecture, leveraging the advantages of Information-Centric Networking (ICN) principles, to enhance the performance, scalability, and reliability of microservice communication. By integrating ICN concepts such as content-based addressing and intelligent routing, the architecture aims to optimize resource utilization, improve system scalability, and ensure secure and efficient communication among microservices. This innovative approach empowers organizations to effectively manage and deploy large-scale distributed microservice architectures, leveraging the benefits of ICN to enhance overall system performance and efficiency.¶
This draft defines a new distributed architecture, called Distributed Architecture for Microservices Communication (DAMC). The overall architecture of this distributed microservices communication shown in Figure 2. It primarily consists of three types of devices shown in Figure 2: Service Gateway (SG), Service Router (SR), and Service Prefix Authentication (SPA) entities,along with a centrally deployed Service Mesh Communication Scheduling Center (SCSC), organized by domain. By incorporating the ICN concept [RFC8793] into the architecture, the DAMC architecture aims to overcome the limitations of the traditional Microservices centralized communication method. It uses content-based addressing [RFC8793] and service prefix [NDN] to uniquely identify and locate microservices, so as to achieve efficient and flexible communication. Service gateway (SG) plays a vital role in service registration, discovery, routing and quality control, while service router promotes the optimal forwarding of communication traffic between microservices. The service prefix authentication (SPA) entity ensures the legitimacy and authorization of the service prefix declared by the microservices, and enhances the security in the distributed microservices environment. In addition, the service mesh communication scheduling center (SCSC) provides effective coordination and allocation of customized forwarding policies between the service gateway and service router (SR) based on the quality detection results reported by SG. This enables intelligent routing decisions to ensure that communication traffic is directed to the most capable and efficient microservices node.¶
+-----------------------------------------------------------------------+ | +---------------+ | | | SCSC | | | Pod 1 +---------------+ Pod 2 | | +-----------------------+ | +------------------------+ | | | service | | | service | | | | +----+ +----+ +----+ | | | +----+ +----+ +----+ | | | | | A/1| | B/1| | ...| | | | |... | | ...| | ...| | | | | +----+ +----+ +----+ | | | +----+ +----+ +----+ | | | +-----------------------+ | +------------------------+ | | \ | / | \ | / | | +----+ +---------+ |_______ +---------+ +----+ | | |SPA |-------| SG-1 |_______/|_ | SG-2 |-------|SPA | | | +----+ +---------+ / | \ +---------+ +----+ | | \ _______|________ / | | \ | / \ | / | | +--- +--- | | / SR \ --------- / SR \ | | ---+ ---+ | | | \ +--- / | | | | / SR \ | | | | ---+ | | | | / \ | | | +----+ +---------+ +---------+ +----+ | | |SPA |-------| SG-3 | | SG-4 |-------|SPA | | | +----+ +---------+ +---------+ +----+ | | / | \ / | \ | | +------------------------+ +------------------------+ | | | +----+ +----+ +----+ | | +----+ +----+ +----+ | | | | |... | |... | | ...| | | | A/4| | B/4| | ...| | | | | +----+ +----+ +----+ | | +----+ +----+ +----+ | | | | service | | service | | | +------------------------+ +------------------------+ | | Pod 3 Pod 4 | +-----------------------------------------------------------------------+ Figure 2 The overall distributed architecture for microservice communication¶
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119] .¶
The following terms are defined in this draft:¶
In this draft, we defines a new distributed architecture for microservice communication. It encompasses all the critical functionalities offered by existing centralized service networks. In the distributed architecture for microservice communication (DAMC), we also define multiple communication entities and clearly define their control signaling message types and functions. These communicating entities play a key role in the architecture, ensuring efficient communication between microservices. The distributed microservice communication architecture DAMC includes the following communication entities:¶
The types and functions of control signaling messages required for communication between entities are shown in Figure 3. The following is an explanation of each signaling:¶
+----------------------------------------------------------------------+
| |Communication |Control Signaling| Control Signaling |
|Class| Entities | Message Types | Function |
+----------------------------------------------------------------------+
| | |Service Prefixes | Microservices within each Pod |
| 1 | Pod/SG | (Name Space) | communicate their used Service |
| | | Announcement | Prefix (Namespace) to the SG. |
+----------------------------------------------------------------------+
| | |Service Prefixes | SG and SR advertise the Servic |
| 2 | SG/ SR | LSA | Prefix and topology link |
| | | | relationship they can reach. |
+----------------------------------------------------------------------+
| | |Service Prefixes |The SG authenticates to the SPA |
| 3 | SG/SPA | Authentication | requested by the Pod is legal. |
+----------------------------------------------------------------------+
| 4 |SG /SR |Service QoS |Communication quality |
| |and SCSC |Telemetry/Service| reporting policies |
| | | QoS Policy | between microservices. |
+----------------------------------------------------------------------+
Figure 3 Key communication message types and functions of DAMC
¶
The key process of the distributed service mesh architecture defined in this draft is as follows:¶
1) The Pod sends the notification signaling to the service gateway (SG), and the notification signaling is used to notify the service gateway linked to each of the pods of the service identification information. The service identification information is the service prefix or namespace of the pod, and the notification signaling is the first signaling defined in the fourth section of the draft. When the microservices Pod needs to send signaling to the service gateway or other microservices, it can send corresponding packets or messages to the target service gateway or microservices through HTTP requests or gRPC calls.¶
2) The Service Gateway (SG) sends an authentication request to the Service Prefix Authentication entity (SPA) through the third signaling, which is used to authenticate whether the service identification information requested by the Pod is legal. If authentication fails, the service prefix authentication (SPA) entity sends an authentication failure notification to the service gateway (SG). If the authentication is passed, perform the operation of sending the second signaling signal from the service gateway (SG) to the service router (SR).¶
3)Acting as the default gateway for the Pod hosting the service, the Service Gateway (SG) absorbs and forwards all Service traffic emitted from that Service Pod. When any microservices in the microservices pod initiates a request or response, all communication traffic will pass through the service gateway, which is responsible for processing and forwarding it to the target microservices or external service. The service gateway plays a key role in the Microservices Pod. It acts as the entrance and exit of communication between all microservices, ensuring the smoothness and reliability of communication.¶
3) After the service prefix authentication (SPA) authentication is passed, the service gateway sends the second signaling to the service router, which is used to notify the topology link relationship and service identification information under various interfaces of the service gateway linked to the Pod to the service router.¶
4) The Service Gateway and Service Router (SR) exchange information about the Service Prefixes they can reach and the interconnectivity topology. Based on the preset algorithm and the topological link relationship，each service gateway and each service router obtain a forwarding information base (FIB) that based on the service identification information, forwarding communication packets according to the forwarding information base (FIB).¶
5) In order to ensure the quality and reliability of communication between microservices, the service gateway needs to understand the health and availability of each target Microservices. To this end, the service gateway will send a detection task to each target microservice, requiring it to self detect. And report the detection result to the corresponding service gateway. Each service gateway receives the detection results reported by the target Microservices, and reports the detection results to the service mesh centralized scheduling center. The Service Gateway and Service Router perform traffic forwarding based on Service Prefixes and the service policies distributed by the Service Mesh Scheduling Center.¶
DAMC, a distributed architecture for microservices communication, addresses the intricate communication demands among microservices in the future, while encompassing all the critical functionalities offered by existing centralized service networks.¶
In this draft, we defines a new distributed architecture for microservices communication. Based on this architecture, the key functions required for communication between microservices are implemented as follows:¶
1) Service registration¶
The Pods send the Service identification information to the Service Gateway (SG).The service identification information is the Service Prefix or Namespace owned by the pod. The Service Gateway facilitates proxy registration by utilizing Service Prefix Announcements. This approach allows the Service Gateway to announce the Service Prefixes it can reach, along with relevant information, enabling other components or services to become aware of and register with the appropriate Service Prefix.¶
2) Service discovery¶
The Microservices information is authenticated to the service prefix authentication (SPA) through the service gateway (SG). After the successful authentication through the service prefix authentication (SPA), the synchronous distribution of Microservices information is realized between the Service Gateway (SG) and the service router (SR) through the distributed protocol. In this process, the Service Gateway (SG) acts as the central point of authentication to achieve secure and reliable communication between Microservices. The service router (SR) plays a crucial role in facilitating the distribution of these verified Microservices information, so as to achieve efficient routing and seamless interaction between Microservices. In this architecture, Service Prefix Authentication (SPA), Service Gateway (SG) and Service Router (SR) jointly establish a powerful and synchronized system, complete the work of agents in the traditional service mesh architecture, and ensure the integrity and consistency of Microservices communication in the distributed service mesh.¶
3) Service measurement¶
The service gateway (SG) detects the target Microservices regularly and automatically according to the demand. The purpose of these probes is to collect information and evaluate the health and availability of the target Microservices. The service gateway (SG) records the detection results and reports them to the Service Mesh Communication Scheduling Center (SCSC). If the detection result does not meet the preset conditions, the service mesh centralized scheduling center generates forwarding policies based on the detection result, and issues the forwarding policies to the service gateway and service router corresponding to the paths of each target Microservices. The detection results do not meet the preset conditions, including at least one of the following:¶
By actively and regularly detecting the target Microservices, the service gateway (SG) ensures the latest and accurate assessment of its status. This proactive approach can identify any potential problems or exceptions, so that timely actions can be taken to ensure the overall reliability and performance of Microservices.¶
4) Service scheduling¶
The Service Mesh Communication Scheduling Center (SCSC) utilizes the quality detection results reported by various service gateways (SG) to distribute customized forwarding policies to service gateways (SG) and service routers (SR) on the communication path. These forwarding policies aim to select the optimal service node from the Microservices pool that provides the same function. By distributing these customized forwarding policies throughout the entire service mesh, the system can intelligently route traffic to the most capable and efficient service node. This ensures that requests are directed to Microservices that exhibit excellent performance, responsiveness, and overall quality. The Service Mesh Communication Scheduling Center (SCSC) plays a crucial role in coordinating the distribution of these customized forwarding policies, ensuring effective utilization of available resources by the network and optimizing overall system performance. By making wise decisions based on the quality detection results, the scheduling center enables the service mesh to dynamically adjust and guide traffic to the most appropriate Microservices, enhance the overall user experience, and maximize the utilization of available resources.¶
Upon receiving requests from clients, the Service Mesh Communication Scheduling Center (SCSC) employs a path selection algorithm, such as Dijkstra's algorithm, to determine the optimal service path based on the target microservice and the current network topology. This ensures that requests are routed through the shortest or most efficient path from the client to the destination microservice. In cases where a microservice's performance deteriorates or a service node experiences a failure, the SCSC leverages the quality detection results to adjust the forwarding strategy. By rerouting requests away from the problematic microservice node and redirecting them to a better-performing node, the SCSC ensures that requests are reliably and efficiently handled. Moreover, during periods of high traffic load or network congestion, the SCSC dynamically adapts the forwarding strategy based on both the topology information and quality detection results. This optimization allows the SCSC to efficiently route traffic, ensuring that requests are promptly processed even under challenging network conditions. By synergizing topology information and quality detection results, the SCSC makes intelligent routing decisions and dynamically adapts the forwarding strategy. This approach guarantees that the service mesh's communication flow is efficiently guided and managed, leading to enhanced overall system performance and improved user experience.¶
In conclusion, the distributed architecture for microservice communication defined in this draft depends on various components, such as service gateway (SG), service router (SR) and Communication Scheduling Center. It realizes efficient and reliable communication between Microservices by using service prefix registration, service prefix authentication, quality detection and customized forwarding policies. This architecture overcomes the limitations of traditional centralized methods and provides improved performance, scalability, and reliability. By using these components and mechanisms, the system can effectively manage the complex communication requirements of large-scale Microservices deployment, and ensure the optimal routing of traffic, thus enhancing the overall system performance and user experience.¶
The distributed architecture for microservices communication consists of the multiple Pods, multiple service gateways, multiple service routers, one Pod linked to one service gateway. The communication process of DAMC is jointly completed by the control plane and the forwarding plane. In the control plane, each component is responsible for managing and controlling the policy, routing and security of Microservices communication, while the forwarding plane is responsible for the actual packet forwarding and flow control.¶
The communication process starts from the control plane, where various components such as service gateway, service prefix authentication, and service router interact through defined signaling types. For example, the service gateway can send an authentication request to the service prefix authentication to verify whether the Microservices has a legal service prefix. These signaling messages are transmitted in the control plane to ensure Microservices authentication, topology information collection and routing policy distribution.¶
The communication process starts from the control plane, where various components such as service gateway, service prefix authentication, and service router interact through defined signaling types. For example, the service gateway can send an authentication request to the service prefix authentication to verify whether the Microservices has a legal service prefix. These signaling messages are transmitted in the control plane to ensure Microservices authentication, topology information collection and routing policy distribution. In the control plane, the service gateway and the service router use the collected information to build a link state database (LSDB) and run routing algorithms (such as Dijkstra algorithm) to generate a routing information base (RIB) and a Forwarding information base (FIB) based on the service prefix. These information bases contain rules and policies on connection between Microservices and packet forwarding.¶
Once the components in the control plane complete coordination and decision-making, the forwarding plane begins to take effect. When a packet arrives at the service gateway, it selects the best path and the next hop according to the rules in the Forwarding information base (FIB) to forward the packet to the target Microservices. In this way, the service gateway and service router can work together to forward data packets along the optimal path, ensuring efficient transmission and correct routing of traffic.¶
1) Service A located within Pod uses the defined class 1 signaling, Service Prefixes (Name Space) Announcement, to notify the connected Service Gateway (SG) of its service prefix or namespace. By adopting this service prefix naming convention, each Microservice can establish its unique identity.¶
2) When the Service Gateway (SG-1) receives a service prefix notification, it initiates the verification process by sending an authentication request to the Service Prefix Authentication (SPA) unit using a defined signaling type (referred to as Class 3 signaling). The purpose of this authentication request is to verify and confirm that Pod indeed has the specified service prefix. By participating in this authentication process, the service gateway ensures that only legitimate Pods with authorized service prefixes are granted access to the network. This robust authentication mechanism adds an additional layer of security and integrity to communication in the service mesh environment.¶
3) When the service gateway (SG-1) completes the authentication of the service prefix, it will use Class 2 signaling to communicate with its connected service router (SR) to announce topology relationships and service prefixes under each interface. By using this specific signaling type, the Service Gateway (SG) transmits information about the entire service mesh topology to the service router, including the connection relationship between the service gateway and the service router, as well as the service prefix associated with each interface. This notification process ensures that various components in the service mesh can accurately understand the topological relationships between each other, providing an important foundation for subsequent traffic forwarding and service routing. In this way, the service gateway and service router can work together to achieve intelligent traffic management and routing decisions, thus providing efficient and reliable Microservices communication.¶
4) Other microservices and service gateways will also adopt a similar process for notification. They will communicate with the Service Gateway (SG) and Service Router (SR) using the corresponding signaling types to inform them of their service prefix information and topology relationships. Through this notification process, various components in the entire service grid can understand each other's existence and functionality, and establish a consistent communication foundation.¶
5) After the Service Gateway (SG) receives Service Prefix LSA from other components, a Link State Database (LSDB) is generated between the Service Gateway and the Service Router based on the service identification information and the topological link relationship. Then, the service gateway and service router will run Dijkstra algorithm to process the data in the link state database （LSDB） to form a routing information base (RIB) and a Forwarding information base (FIB) based on the the service identification information. RIB and FIB will be used to guide traffic forwarding and routing decisions, ensuring that each service node can receive and forward traffic according to the optimal path.¶
In the DAMC, when Microservices Service A/1 needs to communicate with Service B/4, the communication process is facilitated through the service gateways (SG). The service gateways act as intermediaries responsible for managing and controlling communication traffic in the Microservices architecture.¶
1) Service A/1 initiates communication by invoking methods on Service B/4 using the remote method invocation (RMI) pattern. The RMI pattern enables seamless interaction between Microservices as if they were co-located within the same process, regardless of their physical location in the distributed environment.¶
2)The communication message from Service A/1 is directed to the default service gateway (SG-1). The service gateway (SG-1) utilizes a Forwarding Information Base (FIB) table, formed by interactions with the control layer, to determine the next destination for the communication message. The FIB table contains forwarding rules and routing information that guide the message through the network.¶
3) The service gateway (SG-1) forwards the communication message to subsequent service gateways based on the FIB table's rules. Each service gateway in the path takes a step-by-step approach, forwarding the message closer to its destination. Ultimately, the communication message reaches the service gateway (SG-4) associated with the location of Service B/4.¶
4) Upon receiving the communication message, service gateway (SG-4) processes it based on the information specified in the message, directing it to the appropriate Pod where Service B/4 is located. The same process is applied for backhaul traffic, where service gateways handle the routing and forwarding of messages back to their source Pods.¶
Through the above communication process, the distributed architecture for microservice communication realizes effective cooperation between the control plane and the forwarding plane. The control plane is responsible for managing and controlling the strategy and routing of Microservices communication, while the forwarding plane is responsible for actual packet forwarding and traffic management. This layered architecture enables the system to flexibly adapt to changing communication needs and provide reliable communication services.¶