Implementation method and system of non-embedded database based on RocksDB

Abstract

The invention discloses an implementation method and system of a non-embedded database based on RocksDB, and relates to the technical field of database management. Comprising the steps of 1, integrating a service interface of the RocksDB, and packaging a corresponding function to realize a corresponding function of the interface, and 2, receiving a request sent by a client to a database through the service interface of the RocksDB based on an HTTP transmission protocol or a gRPC transmission protocol, and carrying out corresponding operation according to the request: carrying out authentication according to the request, processing and converting the request passing the authentication, and sending the processed and converted request to the database. The method comprises the steps of obtaining a native operation instruction which can be understood by a RocksDB database, executing corresponding data reading, inserting, updating or deleting operation through a RocksDB database engine according to the native operation instruction, ensuring persistent storage of data, and returning an operation result according to an original path through the RocksDB after the operation is completed.

Description

Technical Field

[0001] The present invention discloses a method and system for realizing a non-embedded database based on RocksDB, and relates to the technical field of database management. Background Art

[0002] As a high-performance key-value storage engine, RocksDB is known for its excellent storage performance, high-speed data reading and writing capabilities, and highly stable performance. It performs well in many application scenarios that have strict requirements for low latency and high throughput. It achieves fast and persistent data storage capabilities through carefully designed data structures and algorithm optimizations, such as the use of LSM tree structures, efficient caching strategies, and full use of modern hardware features.

[0003] However, as an embedded database, RocksDB has certain limitations. The use of native RocksDB mainly relies on C++ API. If an application is written in other languages ​​such as Python, Java, Go, etc., using RocksDB directly requires language binding, such as SWIG, Folly's FfiWrapper, etc., or finding a third-party encapsulation library to bridge, which increases the complexity of use and performance loss.

[0004] In addition, since RocksDB itself does not have the ability to directly provide network services to the outside world and does not support direct cross-language calls or remote access, it limits its direct application in distributed systems that interact across platforms and languages. Summary of the invention

[0005] In view of the problems of the prior art, the present invention provides an implementation method and system of a non-embedded database based on RocksDB, which provides the embedded RocksDB with the ability to store external data, so that it can be deployed and run independently without being embedded in an existing system.

[0006] The specific scheme proposed by the present invention is:

[0007] The present invention provides a method for implementing a non-embedded database based on RocksDB, comprising:

[0008] Step 1: Integrate the RocksDB service interface and encapsulate the corresponding functions to implement the corresponding functions of the interface:

[0009] Initialize and configure the service interface: Dynamically configure various parameters of RocksDB according to the server environment, including storage path, cache size, compression algorithm, and write-ahead log WAL strategy.

[0010] Encapsulate read and write operations: define cache strategies, pre-reading mechanisms, and batch operations.

[0011] Define transaction management and concurrency control: Provide support for transaction start, commit, and rollback operations, and set isolation levels to meet the needs of different application scenarios.

[0012] Specifies the network protocol between the client and the backend RocksDB: the client exchanges data with the server across the network through the HTTP transport protocol or the gRPC transport protocol.

[0013] Define the API's GET, PUT, DELETE operations and other operations for read and write processing.

[0014] Provide authentication methods and user rights division: use username and password authentication, or API key and access token authentication, define permission sets through roles, and use roles to facilitate batch authorization and adjustment of permissions.

[0015] Step 2: Receive the request sent by the client to the database through the RocksDB service interface based on the HTTP transport protocol or the gRPC transport protocol, and perform corresponding operations according to the request:

[0016] Authentication is performed based on the request, and the authenticated request is processed and converted to obtain native operation instructions that can be understood by the RocksDB database. According to the native operation instructions, the corresponding data read, insert, update or delete operations are performed through the RocksDB database engine, and the persistent storage of the data is ensured. After the operation is completed, the operation result is returned through RocksDB along the original path.

[0017] Furthermore, in step 1 of the implementation method of a non-embedded database based on RocksDB, the client exchanges data with the server across the network through the HTTP transmission protocol, including: mapping database operations to HTTP verbs and resource paths, providing users with a platform-independent access method, and using the JSON serialization format for data exchange.

[0018] Furthermore, in step 1 of the implementation method of a non-embedded database based on RocksDB, the gRPC transmission protocol is used to enable the client to exchange data with the server across the network, including: building a microservice architecture and real-time data processing application based on the gRPC transmission protocol, and standardizing the interface definition through the gRPC IDL design for collaborative development of the front-end and back-end.

[0019] Furthermore, in step 1 of the implementation method of a non-embedded database based on RocksDB, the GET, PUT, DELETE operations and other operations of the API are defined, including: defining a GET operation for retrieving information, defining a PUT operation for updating existing resources, defining a DELETE operation for removing unnecessary data, and defining other related data management operations for adding, modifying, and querying resources stored in the database system.

[0020] Furthermore, in step 1 of the implementation method of a non-embedded database based on RocksDB, username and password authentication is used, including: providing a preset username and password combination when the user logs in, using a hash algorithm to store the password to prevent password leakage;

[0021] The API key and access token authentication method includes: using the API key to identify the application, issuing an access token after the user successfully authenticates for the first time, and carrying the access token in subsequent requests to prove the identity, avoiding the risk of frequently passing usernames and passwords, and facilitating permission management and revocation.

[0022] The present invention provides a non-embedded database implementation system based on RocksDB, including an interface management module and a database execution module.

[0023] The interface management module integrates the RocksDB service interface and encapsulates the corresponding functions to implement the corresponding functions of the interface:

[0024] Initialize and configure the service interface: Dynamically configure various parameters of RocksDB according to the server environment, including storage path, cache size, compression algorithm, and write-ahead log WAL strategy.

[0025] Encapsulate read and write operations: define cache strategies, pre-reading mechanisms, and batch operations.

[0026] Define transaction management and concurrency control: Provide support for transaction start, commit, and rollback operations, and set isolation levels to meet the needs of different application scenarios.

[0027] Specifies the network protocol between the client and the backend RocksDB: the client exchanges data with the server across the network through the HTTP transport protocol or the gRPC transport protocol.

[0028] Define the API's GET, PUT, DELETE operations and other operations for read and write processing.

[0029] Provide authentication methods and user rights division: use username and password authentication, or API key and access token authentication, define permission sets through roles, and use roles to facilitate batch authorization and adjustment of permissions.

[0030] The database execution module receives requests from clients to the database through the RocksDB service interface based on the HTTP or gRPC transport protocol, and performs corresponding operations based on the requests:

[0031] Authentication is performed based on the request, and the authenticated request is processed and converted to obtain native operation instructions that can be understood by the RocksDB database. According to the native operation instructions, the corresponding data read, insert, update or delete operations are performed through the RocksDB database engine, and the persistent storage of the data is ensured. After the operation is completed, the operation result is returned through RocksDB along the original path.

[0032] Furthermore, the interface management module of the implementation system of a non-embedded database based on RocksDB enables the client to exchange data with the server across the network through the HTTP transmission protocol, including: mapping database operations to HTTP verbs and resource paths, providing users with a platform-independent access method, and using the JSON serialization format for data exchange.

[0033] Furthermore, the interface management module of the implementation system of the non-embedded database based on RocksDB enables the client to exchange data with the server across the network through the gRPC transmission protocol, including: building a microservice architecture and real-time data processing application based on the gRPC transmission protocol, and standardizing the interface definition through the IDL design of gRPC for collaborative development of the front-end and back-end.

[0034] Furthermore, the interface management module of the non-embedded database implementation system based on RocksDB defines the GET, PUT, DELETE operations and other operations of the API, including: defining a GET operation for retrieving information, defining a PUT operation for updating existing resources, defining a DELETE operation for removing unnecessary data, and defining other related data management operations for adding, modifying, and querying resources stored in the database system.

[0035] Further, the interface management module of the implementation system based on the RocksDB non-embedded database uses username and password authentication, including: providing a preset username and password combination when the user logs in, using a hash algorithm to store the password to prevent password leakage;

[0036] The API key and access token authentication method includes: using the API key to identify the application, issuing an access token after the user successfully authenticates for the first time, and carrying the access token in subsequent requests to prove the identity, avoiding the risk of frequently passing usernames and passwords, and facilitating permission management and revocation.

[0037] The benefits of the present invention are:

[0038] Independent service based on integrated RocksDB interface: The present invention integrates RocksDB service interface, so that RocksDB is no longer just a component embedded in other applications as a dependency, but exists as an independently running service entity with its own life cycle management, resource allocation and monitoring system. This deployment method simplifies the coupling between application and database, and facilitates version upgrades, fault isolation and resource optimization.

[0039] The present invention enables any client supporting HTTP protocol to easily interact with RocksDB service to create, read, update and delete data. The universality of this interface greatly broadens the scope of application of RocksDB, whether it is Web application, mobile application or other microservices, it can be seamlessly connected.

[0040] In order to ensure the security of data access, the present invention supports multiple authentication methods, including basic username and password authentication, token authentication, etc. Unauthorized access is effectively prevented, ensuring the legitimacy and security of data access.

[0041] The present invention enables the database system to assign different access rights according to user roles. Roles and permissions can be flexibly defined according to business needs, ensuring that each user or service account can only perform operations within its scope of authority, further refining access control and reducing misoperation and security risks. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a schematic flow chart of the method of the present invention. DETAILED DESCRIPTION

[0043] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0044] Example 1

[0045] The present invention provides a method for implementing a non-embedded database based on RocksDB, comprising:

[0046] Step 1: Integrate the RocksDB service interface and encapsulate the corresponding functions to implement the corresponding functions of the interface:

[0047] Step 11: Initialize and configure the service interface: Dynamically configure various parameters of RocksDB according to the server environment, including storage path, cache size, compression algorithm, and write-ahead log WAL strategy.

[0048] Step 12: Encapsulate read and write operations: define cache strategies, pre-reading mechanisms, and batch operations. This reduces the number of network round trips and improves throughput; at the same time, intelligent cache strategies and pre-reading mechanisms are used to further optimize read performance. For write operations, transaction support is also implemented to ensure data consistency and integrity, such as managing concurrency conflicts through optimistic or pessimistic locking mechanisms.

[0049] Step 13: Define transaction management and concurrency control: Provide support for transaction start, commit, and rollback operations, and set isolation levels to meet the needs of different application scenarios.

[0050] Step 14: Specify the network protocol between the client and the backend RocksDB: Use the HTTP transport protocol or the gRPC transport protocol to allow the client to exchange data with the server across the network.

[0051] The HTTP transport protocol enables the client to exchange data with the server across the network, including mapping database operations to HTTP verbs and resource paths, providing users with platform-independent access methods, and using the JSON serialization format for data exchange. Almost all modern programming languages ​​support JSON parsing and generation, greatly reducing the threshold for integration. For users who prefer the HTTP protocol or need to quickly build prototypes and maintain web compatibility, a complete HTTP interface calling method is provided.

[0052] The gRPC transport protocol enables the client to exchange data with the server across the network, including: building microservice architecture and real-time data processing applications based on the gRPC transport protocol, and standardizing interface definitions through gRPC's IDL design for collaborative development of the front-end and back-end. gRPC is based on ProtoBuf (Protocol Buffers) as its efficient and compact serialization protocol, which can greatly reduce the burden of network transmission compared to JSON. Through the gRPC interface, we have opened up another way to efficiently access RocksDB services for users who pursue extreme performance and need rich RPC functions.

[0053] Step 15: Define the API's GET, PUT, DELETE operations and other operations for read and write processing.

[0054] It defines the GET, PUT, DELETE and other operations of the API, including: defining the GET operation for retrieving information, defining the PUT operation for updating existing resources, defining the DELETE operation for removing unnecessary data, and defining other related data management operations for adding, modifying and querying resources stored in the database system. The API operation design follows the REST principle to ensure that each interface is predictable and the response format is unified, with JSON as the default, to facilitate cross-platform data exchange.

[0055] Step 16: Provide authentication methods and user rights division: Use username and password authentication, or API key and access token authentication, define permission sets through roles, and use roles to facilitate batch authorization and adjustment of permissions.

[0056] The user name and password authentication is used, including: providing a preset user name and password combination when the user logs in, using a hash algorithm to store the password to prevent password leakage;

[0057] The API key and access token authentication method includes: using the API key to identify the application, issuing an access token after the user successfully authenticates for the first time, and carrying the access token in subsequent requests to prove the identity, avoiding the risk of frequently passing usernames and passwords, and facilitating permission management and revocation.

[0058] In addition, a series of permission sets are defined through roles, representing a class of users or services with the same permission requirements. The design of roles makes permission management more flexible and efficient, and facilitates batch authorization and adjustment of permissions. For example, the permissions in the database system are subdivided into multiple operation permissions such as create (Create), read (Read), update (Update), delete (Delete, i.e. CURD), which can be flexibly configured according to actual needs. Each user can be assigned to one or more roles, and can also be managed in batches through user groups. Users in the user group automatically inherit the roles and permissions in the group, which greatly simplifies the complexity of permission management. Ensure that each user can only access and operate the data and resources that they are explicitly authorized to. For operations without permission, timely feedback "no permission" prompts are given to clearly inform users that their access is denied to protect data security. Through the implementation of the above-mentioned authentication function and permission division mechanism, this method not only strengthens the security of the database system, but also ensures the transparency and compliance of data access, providing a solid and reliable basic support for various applications.

[0059] Step 2: Receive the request sent by the client to the database through the RocksDB service interface based on the HTTP transport protocol or the gRPC transport protocol, and perform corresponding operations according to the request:

[0060] Authentication is performed based on the request, and the authenticated request is processed and converted to obtain native operation instructions that can be understood by the RocksDB database. According to the native operation instructions, the corresponding data read, insert, update or delete operations are performed through the RocksDB database engine, and the persistent storage of the data is ensured. After the operation is completed, the operation result is returned through RocksDB along the original path.

[0061] The specific process can be:

[0062] Request initiation: First, the client application constructs corresponding CRUD requests according to business needs, including inserting new data (Create), retrieving existing data (Read), modifying data (Update), or deleting data items (Delete). These requests are encapsulated into data packets that comply with the HTTP or gRPC protocol for easy transmission over the network.

[0063] Protocol transmission: Using HTTP or gRPC as the transmission protocol, these requests are sent securely and efficiently from the client to the RocksDB database server. HTTP is known for its universality and ease of use and is suitable for most web applications; while gRPC performs well in scenarios that require efficient communication due to its high performance, low latency, and bidirectional streaming features.

[0064] Authentication and authorization: After reaching the server, the request first enters authentication to verify the legitimacy of the request, check access tokens, API keys or user credentials, etc., to ensure that only authorized clients can proceed to the next step. This step effectively blocks unauthorized access.

[0065] Request processing and conversion: After authentication, the request is forwarded to the server responsible for handling CRUD operations. It unpacks HTTP / gRPC requests and converts them into native operation instructions that the RocksDB database can understand, such as converting HTTP GET requests into RocksDB GET operations, POST requests into PUT operations, and so on.

[0066] Data manipulation and persistence: Finally, the converted instructions are sent to the RocksDB database engine. After receiving these operation instructions, RocksDB performs the corresponding data read, insert, update or delete operations and ensures the persistent storage of data. Thanks to the high performance and low latency characteristics of RocksDB, even large-scale data operations can be completed efficiently.

[0067] Response and feedback: After the operation is completed, RocksDB returns the operation result through the original path, and then encapsulates the operation result into an HTTP or gRPC response, and finally feeds it back to the client. The client determines whether the operation is successful based on the response result and makes corresponding processing accordingly, such as displaying data, prompting the user, or performing the next logical operation.

[0068] Example 2

[0069] The present invention provides a non-embedded database implementation system based on RocksDB, including an interface management module and a database execution module.

[0070] The interface management module integrates the RocksDB service interface and encapsulates the corresponding functions to implement the corresponding functions of the interface:

[0071] Initialize and configure the service interface: Dynamically configure various parameters of RocksDB according to the server environment, including storage path, cache size, compression algorithm, and write-ahead log WAL strategy.

[0072] Encapsulate read and write operations: define cache strategies, pre-reading mechanisms, and batch operations.

[0073] Define transaction management and concurrency control: Provide support for transaction start, commit, and rollback operations, and set isolation levels to meet the needs of different application scenarios.

[0074] Specifies the network protocol between the client and the backend RocksDB: the client exchanges data with the server across the network through the HTTP transport protocol or the gRPC transport protocol.

[0075] Define the API's GET, PUT, DELETE operations and other operations for read and write processing.

[0076] Provide authentication methods and user rights division: use username and password authentication, or API key and access token authentication, define permission sets through roles, and use roles to facilitate batch authorization and adjustment of permissions.

[0077] The database execution module receives requests from clients to the database through the RocksDB service interface based on the HTTP or gRPC transport protocol, and performs corresponding operations based on the requests:

[0078] Authentication is performed based on the request, and the authenticated request is processed and converted to obtain native operation instructions that can be understood by the RocksDB database. According to the native operation instructions, the corresponding data read, insert, update or delete operations are performed through the RocksDB database engine, and the persistent storage of the data is ensured. After the operation is completed, the operation result is returned through RocksDB along the original path.

[0079] As the information interaction and execution process between the modules in the above-mentioned system are based on the same concept as the embodiment of the method of the present invention, the specific contents can be found in the description of the embodiment of the method of the present invention and will not be repeated here.

[0080] Likewise, the benefits of the system of the present invention are:

[0081] Independent service based on integrated RocksDB interface: The present invention integrates RocksDB service interface, so that RocksDB is no longer just a component embedded in other applications as a dependency, but exists as an independently running service entity with its own life cycle management, resource allocation and monitoring system. This deployment method simplifies the coupling between application and database, and facilitates version upgrades, fault isolation and resource optimization.

[0082] The present invention enables any client supporting HTTP protocol to easily interact with RocksDB service to create, read, update and delete data. The universality of this interface greatly broadens the scope of application of RocksDB, whether it is Web application, mobile application or other microservices, it can be seamlessly connected.

[0083] In order to ensure the security of data access, the present invention supports multiple authentication methods, including basic username and password authentication, token authentication, etc. Unauthorized access is effectively prevented, ensuring the legitimacy and security of data access.

[0084] The present invention enables the database system to assign different access rights according to user roles. Roles and permissions can be flexibly defined according to business needs, ensuring that each user or service account can only perform operations within its scope of authority, further refining access control and reducing misoperation and security risks.

[0085] It should be noted that not all steps and modules in the above-mentioned processes and system structures are necessary, and some steps or modules can be ignored according to actual needs. The execution order of each step is not fixed and can be adjusted as needed. The system structure described in the above-mentioned embodiments can be a physical structure or a logical structure, that is, some modules may be implemented by the same physical entity, or some modules may be implemented by multiple physical entities, or some components in multiple independent devices may be implemented together.

[0086] The above-described embodiments are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or changes made by those skilled in the art based on the present invention are within the protection scope of the present invention. The protection scope of the present invention shall be subject to the claims.

Claims

1. A method for implementing a non-embedded database based on RocksDB, characterized in that include: Step 1: Integrate the RocksDB service interface and encapsulate the corresponding functions to implement the corresponding functions of the interface: Initialize and configure the service interface: Dynamically configure various parameters of RocksDB according to the server environment, including storage path, cache size, compression algorithm, and write-ahead log WAL strategy. Encapsulate read and write operations: define cache strategies, pre-reading mechanisms, and batch operations. Define transaction management and concurrency control: Provide support for transaction start, commit, and rollback operations, and set isolation levels to meet the needs of different application scenarios. Specifies the network protocol between the client and the backend RocksDB: the client exchanges data with the server across the network through the HTTP transport protocol or the gRPC transport protocol. Define the API's GET, PUT, DELETE operations and other operations for read and write processing. Provide authentication methods and user rights division: use username and password authentication, or API key and access token authentication, define permission sets through roles, and use roles to facilitate batch authorization and adjustment of permissions. Step 2: Receive the request sent by the client to the database through the RocksDB service interface based on the HTTP transport protocol or the gRPC transport protocol, and perform corresponding operations according to the request: Authentication is performed based on the request, and the authenticated request is processed and converted to obtain native operation instructions that can be understood by the RocksDB database. According to the native operation instructions, the corresponding data read, insert, update or delete operations are performed through the RocksDB database engine, and the persistent storage of the data is ensured. After the operation is completed, the operation result is returned through RocksDB along the original path.

2. The implementation method of a non-embedded database based on RocksDB according to claim 1, characterized in that In step 1, the client exchanges data with the server across the network through the HTTP transmission protocol, including: mapping database operations to HTTP verbs and resource paths, providing users with a platform-independent access method, and using the JSON serialization format for data exchange.

3. According to claim 1, a method for implementing a non-embedded database based on RocksDB is characterized in that in step 1, the client exchanges data with the server across the network through the gPRC transmission protocol, comprising: Build microservice architecture and real-time data processing applications based on the gRPC transmission protocol, and use gRPC's IDL design to standardize interface definitions for collaborative development of the front-end and back-end.

4. The implementation method of a non-embedded database based on RocksDB according to claim 1, characterized in that In step 1, define the GET, PUT, DELETE operations and other operations of the API, including: define the GET operation for retrieving information, define the PUT operation for updating existing resources, define the DELETE operation for removing unnecessary data, and define other related data management operations for adding, modifying, and querying resources stored in the database system.

5. The method for implementing a non-embedded database based on RocksDB according to claim 1, characterized in that In step 1, username and password authentication is used, including: providing a preset username and password combination when the user logs in, and using a hash algorithm to store the password to prevent password leakage; The API key and access token authentication method includes: using the API key to identify the application, issuing an access token after the user successfully authenticates for the first time, and carrying the access token in subsequent requests to prove the identity, avoiding the risk of frequently passing usernames and passwords, and facilitating permission management and revocation.

6. A non-embedded database implementation system based on RocksDB, characterized by Including interface management module and database execution module, The interface management module integrates the RocksDB service interface and encapsulates the corresponding functions to implement the corresponding functions of the interface: Initialize and configure the service interface: Dynamically configure various parameters of RocksDB according to the server environment, including storage path, cache size, compression algorithm, and write-ahead log WAL strategy. Encapsulate read and write operations: define cache strategies, pre-reading mechanisms, and batch operations. Define transaction management and concurrency control: Provide support for transaction start, commit, and rollback operations, and set isolation levels to meet the needs of different application scenarios. Specifies the network protocol between the client and the backend RocksDB: the client exchanges data with the server across the network through the HTTP transport protocol or the gRPC transport protocol. Define the API's GET, PUT, DELETE operations and other operations for read and write processing. Provide authentication methods and user rights division: use username and password authentication, or API key and access token authentication, define permission sets through roles, and use roles to facilitate batch authorization and adjustment of permissions. The database execution module receives requests from clients to the database through the RocksDB service interface based on the HTTP or gRPC transport protocol, and performs corresponding operations based on the requests: Authentication is performed based on the request, and the authenticated request is processed and converted to obtain native operation instructions that can be understood by the RocksDB database. According to the native operation instructions, the corresponding data read, insert, update or delete operations are performed through the RocksDB database engine, and the persistent storage of the data is ensured. After the operation is completed, the operation result is returned through RocksDB along the original path.

7. The implementation system of a non-embedded database based on RocksDB according to claim 6, characterized in that the interface The management module enables the client to exchange data with the server across the network through the HTTP transmission protocol, including: mapping database operations to HTTP verbs and resource paths, providing users with platform-independent access methods, and using the JSON serialization format for data exchange.

8. The implementation system of a non-embedded database based on RocksDB according to claim 6, characterized in that the interface The management module uses the gRPC transmission protocol to enable the client to exchange data with the server across the network, including: building a microservice architecture and real-time data processing application based on the gRPC transmission protocol, and standardizing interface definitions through gRPC's IDL design for collaborative development of the front-end and back-end.

9. The implementation system of a non-embedded database based on RocksDB according to claim 6, characterized in that the interface The management module defines the GET, PUT, DELETE operations and other operations of the API, including: defining the GET operation for retrieving information, defining the PUT operation for updating existing resources, defining the DELETE operation for removing unnecessary data, and defining other related data management operations for adding, modifying, and querying resources stored in the database system.

10. The implementation system of a non-embedded database based on RocksDB according to claim 6, characterized in that the interface The management module uses username and password authentication, including: providing a pre-set username and password combination when the user logs in, using a hash algorithm to store the password to prevent password leakage; The API key and access token authentication method includes: using the API key to identify the application, issuing an access token after the user successfully authenticates for the first time, and carrying the access token in subsequent requests to prove the identity, avoiding the risk of frequently passing usernames and passwords, and facilitating permission management and revocation.

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