Data protocol conversion middleware and data protocol conversion method

Abstract

The present invention discloses a data protocol conversion middleware and a data protocol conversion method, including: a protocol initialization module, the protocol initialization module is used to load the static configuration data and dynamic cache data of the corresponding system, generate a protocol component instance, and the protocol component instance includes a protocol business interface; a protocol data interface, the protocol data interface is used to use a data interaction queue to realize interactive communication between different protocol component instances; an encoder, the encoder is used to de-business the received business data; a decoder, the decoder is used to perform local business processing on the received data to obtain local business data; a business logic conversion module, the business logic conversion module is used to perform business logic conversion on the local business data based on the static configuration data and the dynamic cache data according to the protocol service. The present invention maintains the robustness and stability of the original system, has good reusability, and greatly improves the efficiency of development and implementation.

Description

Technical Field

[0001] The present invention relates to the technical field of data protocol conversion, and in particular to a data protocol conversion middleware and a data protocol conversion method. Background Art

[0002] In the Internet of Things and distributed systems, data transmission protocols play an important role in order to enable effective communication between different systems. They allow data interaction between systems to be performed through various I / O behaviors based on the reduction and protocols implemented by each independent system. At present, the traditional way to implement the protocol docking between the two parties is that the two parties agree that one of the systems will adapt to the protocol of the other system to develop customized code, convert it into the protocol form and data format of the other system, which is suitable for systems under development and has a small implementation workload. Another way is to introduce a specially developed middleware for protocol conversion development, decouple the work of protocol conversion from the two systems, and deploy the middleware implementation independently. It is suitable for legacy systems or systems that cannot be iteratively developed, and has a large implementation workload.

[0003] For the first method, protocol conversion development in the original system can only be led by the developers of the original system or programmers who are familiar with the original system, and will affect the robustness of the original system to a certain extent; adding changes to the interface docking on the basis of the original system will destroy the stability of the original system to a certain extent, and may even cause the original system to malfunction. The system change release process in a certain software standard process system will increase the corresponding review and testing links, increasing the implementation cycle and cost of the system. For the second method, the use of independently developed middleware will result in a large development workload and poor reusability. It can only be applied to specific scenarios where the original system protocol is converted to a specific protocol. Other scenarios cannot be fully reused and need to be redeveloped or changed.

[0004] Therefore, a data protocol conversion middleware and a data protocol conversion method are developed to solve the above problems. Summary of the invention

[0005] The present invention provides a data protocol conversion middleware and a data protocol conversion method to solve the problem that the existing protocol conversion middleware may affect the robustness and stability of the original system and has poor reusability.

[0006] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0007] A data protocol conversion middleware, comprising: a standardized protocol component, wherein the standardized protocol component comprises:

[0008] A protocol initialization module, which is used to load static configuration data and dynamic cache data of the corresponding system and generate a protocol component instance, wherein the protocol component instance includes a protocol business interface and a protocol service, wherein the protocol business interface is used to send or receive business data and the protocol service is used for business logic conversion;

[0009] A protocol data interface, wherein the protocol data interface is used to implement interactive communication between different protocol component instances using a data interaction queue;

[0010] An encoder, the encoder is used to de-service the received service data;

[0011] A decoder, wherein the decoder is used to perform local business processing on the received data to obtain local business data;

[0012] A business logic conversion module, the business logic conversion module is used to perform business logic conversion on the local business data based on the static configuration data and the dynamic cache data according to the protocol service;

[0013] A configuration structure, wherein the configuration structure is used to store the static configuration data;

[0014] A cache structure is used to store the dynamic cache data.

[0015] Furthermore, the data interaction queue is a bidirectional blocking queue based on first-in-first-out.

[0016] Furthermore, the data interaction queue is connected to the protocol component instance via a southbound interface or a northbound interface.

[0017] Furthermore, the framework queue of the data interaction queue includes an asynchronous queue and a synchronous channel.

[0018] Furthermore, it also includes a protocol component base, which is used to encapsulate multiple standardized protocol components and all exposed protocol business interfaces into an underlying driver that can carry and run protocol component instances. When the protocol component base is started, it will trigger the operation and loading of the protocol initialization module of the standardized protocol component.

[0019] Furthermore, it also includes a protocol conversion framework, which includes an operation monitoring module, a debugging module, a traffic statistics module, a control module, a filtering module, a parameter configuration module and an operation and maintenance web interface. The filtering module is used to filter the data interaction queue, the debugging module is used to debug the data interaction queue, the operation monitoring module is used to monitor the operation of the data interaction queue, the parameter configuration module is used to load the initialization parameter configuration of the data interaction queue, and the control module is used to control the start, stop and current limiting of the data interaction queue.

[0020] The present invention also provides a data protocol conversion method, comprising:

[0021] Constructing a standardized protocol component, the standardized protocol component includes a protocol initialization module, a protocol data interface, a configuration structure, a cache structure, a business logic conversion module, an encoder and a decoder;

[0022] By using the protocol initialization modules of the standardized protocol components, the static configuration data and the dynamic cache data of the corresponding systems are loaded into the configuration structure and the cache structure respectively, so as to obtain a plurality of local system protocol component instances and peer system protocol component instances, wherein the corresponding protocol component instances all include a protocol business interface and a protocol service, wherein the protocol business interface is used to send or receive business data, and the protocol service is used for business logic conversion;

[0023] Enter the conversion process:

[0024] Receive the service data to be converted in the local system through the protocol service interface of the local system protocol component instance;

[0025] Performing business logic conversion on the business data to be converted based on the static configuration data and dynamic cache data of the local system through the protocol service of the local system protocol component instance to obtain business logic conversion data;

[0026] De-service the service logic conversion data using an encoder of the local system protocol component instance to obtain de-service data;

[0027] The de-serviced data is transmitted to the peer system protocol component instance through the protocol data interface based on the data interaction queue;

[0028] Performing local business processing on the de-businessized data through a decoder of the peer system protocol component instance to obtain local businessized data;

[0029] Performing business logic conversion on the local business data based on the static configuration data and dynamic cache data of the peer system through the protocol service of the peer system protocol component instance to obtain business data in a target protocol format;

[0030] Pushing the target protocol format service data to the peer system through the protocol service interface of the peer system protocol component instance;

[0031] If the business data is PUSH behavior data, then the conversion operation process ends;

[0032] If the service data is ACK behavior data, the feedback result sent by the opposite end system after receiving the service data in the target protocol format is processed in the reverse process of the conversion operation flow and then flows back to the local end system.

[0033] Furthermore, the data interaction queue is a bidirectional blocking queue based on first-in-first-out.

[0034] Furthermore, the framework queue of the data interaction queue includes an asynchronous queue and a synchronous channel, the local system protocol component instance actively pushes data through the asynchronous queue, the opposite system protocol component instance passively receives the data pushed by the local system protocol component instance through the asynchronous queue, the local system protocol component instance actively requests data through the synchronous channel, and the opposite system protocol component instance passively responds to the request of the local system protocol component instance through the synchronous channel and sends data to the local system protocol component instance.

[0035] Furthermore, the calculation formula of the maximum number of queues m of the data interaction queue is as follows:

[0036] m=n(n-1)

[0037] n is the number of standardized protocol components.

[0038] The beneficial effects of the present invention are:

[0039] The data protocol conversion middleware and data protocol conversion method proposed by the present invention are independent of the original system, maintain the robustness and stability of the original system, have good reusability, and greatly improve the efficiency of development and implementation. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a structural diagram of a data protocol conversion middleware in an embodiment of the present application;

[0041] Figure 2 This is a structural diagram of the standardized protocol components in the embodiments of the present application;

[0042] Figure 3This is an operation logic diagram of the protocol component base in the embodiment of the present application;

[0043] Figure 4 This is a schematic diagram of the structure of the data interaction queue in the embodiment of the present application;

[0044] Figure 5 It is a method flow logic diagram of the local system protocol component, the opposite system protocol component and the interaction queue in the embodiment of the present application;

[0045] Figure 6 A logical structure diagram of the interaction queues between the standardized protocol components in the embodiment of the present application;

[0046] Figure 7 This is a structural diagram of the protocol conversion framework in the embodiment of the present application. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0048] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0050] In the description of the present invention, it should be understood that the terms "upper", "lower", "inside", "outside", "left", "right", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are directions or positional relationships in which the product of the invention is usually placed when in use, or are directions or positional relationships commonly understood by those skilled in the art. These directions or positional relationships are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0051] Furthermore, the terms “first”, “second”, etc. are merely used for distinguishing descriptions and should not be understood as indicating or implying relative importance.

[0052] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms such as "setting" and "connection" should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0053] The specific implementation modes of the present invention are described in detail below in conjunction with the accompanying drawings.

[0054] Combination Figure 1 and Figure 2 As shown, a data protocol conversion middleware includes: a standardized protocol component, and the standardized protocol component includes:

[0055] A protocol initialization module, which is used to load static configuration data and dynamic cache data of the corresponding system and generate a protocol component instance, wherein the protocol component instance includes a protocol business interface and a protocol service, wherein the protocol business interface is used to send or receive business data and the protocol service is used for business logic conversion;

[0056] A protocol data interface, wherein the protocol data interface is used to implement interactive communication between different protocol component instances using a data interaction queue;

[0057] An encoder, the encoder is used to de-service the received service data;

[0058] A decoder, wherein the decoder is used to perform local business processing on the received data to obtain local business data;

[0059] A business logic conversion module, the business logic conversion module is used to perform business logic conversion on the local business data based on the static configuration data and the dynamic cache data according to the protocol service;

[0060] A configuration structure, wherein the configuration structure is used to store the static configuration data;

[0061] A cache structure is used to store the dynamic cache data.

[0062] like Figure 4 As shown, in some embodiments, the data interaction queue is a bidirectional blocking queue based on first-in-first-out.

[0063] Specifically, the data interaction queue is a first-in-first-out (FIFO)-bidirectional (Deque)-blocking queue based on specific data, and is composed of additional traffic counting / traffic statistics queues, data debugging, data control and other attribute controls. When the framework is started, several data interaction queues will be established according to the number of each standardized protocol component, which is specified by the configuration parameters of the framework. The maximum number is that all standardized protocol components and other protocol standardized components have two bidirectional queues, namely:

[0064] The maximum number of queues m = n(n-1), where n is the number of standardized protocol components.

[0065] In some embodiments, the data interaction queue is connected to the protocol component instance via a southbound interface or a northbound interface.

[0066] like Figure 5 and Figure 6 As shown in the figure, the southbound interface is the connection interface from the higher layer to the lower layer device, and the northbound interface is the interface from the lower layer to the higher layer. The southbound interface and the northbound interface are the interaction interfaces with the data interaction queue in the operation of the standardized protocol component in the protocol component base, which are defined as two pairs of push() / rec() and ack() / reack(), corresponding to the local end and the opposite end of the data interaction respectively, and are divided into PUSH and GET according to the types of general data interaction behaviors, among which:

[0067] PUSH: When the local protocol component needs to actively push data, it generally uses asynchronous push (async-push) mode, which is similar to the push() method in the standardized protocol component. The data is pushed / produced to the data interaction queue, and the peer protocol component receives / consumes data through the data interaction queue of the same channel through the rec() method. Vice versa, the push() method of data production on the peer side -> data interaction queue -> rec() method of data consumption on the local side completes the complete reverse data flow.

[0068] GET: When the protocol component on this end needs to request data, it uses a synchronous response (sync-response) method, which is compared to the ack() method in the standardized protocol component, and is directly connected to the reack() method in the specified peer protocol component through the synchronous channel in the protocol conversion framework, and synchronously blocks until the method execution business is completed, and then responds to the output of the ack() method. Vice versa, the peer's synchronous request ack() method -> synchronous channel -> the local reack() receives and responds -> the peer's ack() method responds and outputs, completing the complete reverse data flow.

[0069] like Figure 2 As shown, in some embodiments, a protocol service interface is also included, and the protocol service interface is used for external operation and control of the protocol.

[0070] like Figure 1 As shown, in some embodiments, a data protocol conversion middleware further includes a protocol component base, which is used to encapsulate multiple standardized protocol components and all exposed protocol service interfaces into an underlying driver that can carry and run protocol component instances. When the protocol component base is started, it triggers the operation and loading of protocol initialization modules of all standardized protocol components. Figure 3 As shown in the figure, the protocol component base drives the standardized protocol component to complete the process of middleware operation and component business loading: the protocol component base executes the method init() of loading the initialization part of each standardized protocol component as the middleware runs. The init() method of each standardized protocol component loads the system environment parameters and configuration data that meet the operation of the protocol in a specific field environment from the database system and static configuration files yaml, properties, etc. according to its own configuration, and calls the load() method to load it into the static configuration data structure and dynamic cache data structure for the protocol conversion process to use as needed. The protocol business interface function is started to expose the user interaction interface. At this time, the protocol component base is running normally, and each standardized protocol component is started and completed, officially entering the protocol conversion operation stage.

[0071] like Figure 7 As shown, in some embodiments, a data protocol conversion middleware also includes a protocol conversion framework, and the protocol conversion framework includes an operation monitoring module, a debugging module, a traffic statistics module, a control module, a filtering module, a parameter configuration module and an operation and maintenance web interface. The filtering module is used to filter the data interaction queue, the debugging module is used to debug the data interaction queue, the operation monitoring module is used to monitor the operation of the data interaction queue, the parameter configuration module is used to load the initialization parameter configuration of the data interaction queue, and the control module is used to control the start, stop and current limiting of the data interaction queue.

[0072] like Figure 2 As shown, this embodiment also provides a data protocol conversion method, including:

[0073] Constructing a standardized protocol component, the standardized protocol component includes a protocol initialization module, a protocol data interface, a configuration structure, a cache structure, a business logic conversion module, an encoder and a decoder;

[0074] By using the protocol initialization modules of the standardized protocol components, the static configuration data and the dynamic cache data of the corresponding systems are loaded into the configuration structure and the cache structure respectively, so as to obtain a plurality of local system protocol component instances and peer system protocol component instances, wherein the corresponding protocol component instances all include a protocol business interface and a protocol service, wherein the protocol business interface is used to send or receive business data, and the protocol service is used for business logic conversion;

[0075] Enter the conversion process:

[0076] Receive the service data to be converted in the local system through the protocol service interface of the local system protocol component instance;

[0077] De-service the service data to be converted by using an encoder of the local system protocol component instance to obtain de-service data;

[0078] The de-serviced data is transmitted to the peer system protocol component instance through the protocol data interface based on the data interaction queue;

[0079] Performing local business processing on the de-businessized data through a decoder of the peer system protocol component instance to obtain local businessized data;

[0080] Performing business logic conversion on the local business data based on the static configuration data and the dynamic cache data through the protocol service of the peer system protocol component instance to obtain business data in a target protocol format;

[0081] Pushing the target protocol format service data to the peer system through the protocol service interface of the peer system protocol component instance;

[0082] If the business data is PUSH behavior data, then the conversion operation process ends;

[0083] If the service data is ACK behavior data, the feedback result sent by the opposite end system after receiving the service data in the target protocol format is processed in the reverse process of the conversion operation flow and then flows back to the local end system.

[0084] In some embodiments, the data interaction queue is a bidirectional blocking queue based on first-in-first-out.

[0085] In some embodiments, the framework queue of the data interaction queue includes an asynchronous queue and a synchronous channel, the local system protocol component instance actively pushes data through the asynchronous queue, the opposite system protocol component instance passively receives the data pushed by the local system protocol component instance through the asynchronous queue, the local system protocol component instance actively requests data through the synchronous channel, and the opposite system protocol component instance passively responds to the request of the local system protocol component instance through the synchronous channel and sends data to the local system protocol component instance.

[0086] In some embodiments, the calculation formula for the maximum number of queues m of the data interaction queue is as follows:

[0087] m=n(n-1)

[0088] n is the number of standardized protocol components.

[0089] The advantages of the present invention compared to the prior art are:

[0090] Compared with the general protocol conversion solution between multiple systems, it not only reduces the interference with the original system, but also minimizes the impact on the stability of the entire system. It is completely separated from the original system for independent deployment and installation. It can share computing resources with the original system, or be deployed separately in different computing resource environments accessible by the network. The operation of this middleware is completely independent of the original system and has no perception of the original system.

[0091] For the development of general customized interface docking and protocol conversion functions, this patent provides an implementation method based on standardized protocol components. The development process is standardized. For developers, an easy-to-understand development method is adopted. The development learning difficulty is relatively low, and it can be quickly implemented and put into use. Moreover, due to the emphasis on standardization, it is easier and more relaxed to carry out secondary development of similar functions. In the implementation architecture of the example of this patent, the degree of encapsulation of the two agreements is very high, and they can be independently outsourced as components for development and version management. The middleware framework and protocol components can be separated for their own iterations without being affected. The entire middleware instance is built based on the framework and protocol components. Therefore, the developed protocols and interfaces can be completely reused without re-development. Only the appropriate protocol components need to be selected for construction, which greatly improves the efficiency of development and implementation.

[0092] In response to the docking function requirements of customized multi-party systems, this patent provides a decoupled framework middleware, and a plug-in development mechanism based on independent standardized protocol components. Protocol developers only need to focus on the business function implementation of the protocol itself, and do not even need to consider the logic of software and system operation, preventing excessive design and consideration of non-functional requirements, reducing the corresponding systemic defects and problems in the software, and ensuring its stability and robustness to the greatest extent. Ordinary middleware that is often developed for protocol conversion in the original system or developed independently only implements its basic business functions: direct data conversion tasks in accordance with the protocol form, and due to development progress and cost considerations, it will not complete too many additional scalability and maintenance functions. In the middleware framework of this patent technology, after the construction and deployment of the protocol conversion middleware is completed in a patchwork manner, the framework itself will have considerable operability and operational functions for the data interaction between protocol components. In addition to functions such as data flow statistics, self-monitoring, version upgrades, debugging log viewing, and interface documentation that facilitate system and data debugging, it also integrates configuration changes, data statistics, and codeless configuration of simple protocols to improve product efficiency and corresponding operation and maintenance functions.

[0093] For the protocol conversion process itself, this patent provides all-round data debugging, data control, performance monitoring and other convenient system measurement and maintenance capabilities, and more effectively and transparently monitors and regulates the protocol conversion process in real time. It effectively ensures the stable operation of the function, discovers problems in time, and greatly reduces its operation and maintenance costs.

[0094] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A data protocol conversion middleware, characterized in that: include: A standardized protocol component, the standardized protocol component comprising: A protocol initialization module, which is used to load static configuration data and dynamic cache data of the corresponding system and generate a protocol component instance, wherein the protocol component instance includes a protocol business interface and a protocol service, wherein the protocol business interface is used to send or receive business data and the protocol service is used for business logic conversion; A protocol data interface, wherein the protocol data interface is used to implement interactive communication between different protocol component instances using a data interaction queue; An encoder, the encoder is used to de-service the received service data; A decoder, wherein the decoder is used to perform local business processing on the received data to obtain local business data; A business logic conversion module, the business logic conversion module is used to perform business logic conversion on the local business data based on the static configuration data and the dynamic cache data according to the protocol service; A configuration structure, wherein the configuration structure is used to store the static configuration data; A cache structure is used to store the dynamic cache data.

2. A data protocol conversion middleware according to claim 1, characterized in that: The data interaction queue is a bidirectional blocking queue based on first-in-first-out.

3. A data protocol conversion middleware according to claim 1, characterized in that: The data interaction queue is connected to the protocol component instance via a southbound interface or a northbound interface.

4. A data protocol conversion middleware according to claim 1, characterized in that: The framework queue of the data interaction queue includes an asynchronous queue and a synchronous channel.

5. The data protocol conversion middleware according to claim 1, characterized in that: It also includes a protocol component base, which is used to encapsulate multiple standardized protocol components and all exposed protocol business interfaces into an underlying driver that can carry and run protocol component instances. When the protocol component base is started, it will trigger the operation and loading of the protocol initialization module of the standardized protocol component.

6. A data protocol conversion middleware according to claim 1, characterized in that: It also includes a protocol conversion framework, which includes an operation monitoring module, a debugging module, a traffic statistics module, a control module, a filtering module, a parameter configuration module and an operation and maintenance web interface. The filtering module is used to filter the data interaction queue, the debugging module is used to debug the data interaction queue, the operation monitoring module is used to monitor the operation of the data interaction queue, the parameter configuration module is used to load the initialization parameter configuration of the data interaction queue, and the control module is used to control the start, stop and current limiting of the data interaction queue.

7. A data protocol conversion method for a data protocol conversion middleware according to any one of claims 1 to 6, characterized in that: include: Constructing a standardized protocol component, the standardized protocol component includes a protocol initialization module, a protocol data interface, a configuration structure, a cache structure, a business logic conversion module, an encoder and a decoder; By using the protocol initialization modules of the standardized protocol components, the static configuration data and the dynamic cache data of the corresponding systems are loaded into the configuration structure and the cache structure respectively, so as to obtain a plurality of local system protocol component instances and peer system protocol component instances, wherein the corresponding protocol component instances all include a protocol business interface and a protocol service, wherein the protocol business interface is used to send or receive business data, and the protocol service is used for business logic conversion; Enter the conversion process: Receiving the service data to be converted in the local system through the protocol service interface of the local system protocol component instance; Performing business logic conversion on the business data to be converted based on the static configuration data and dynamic cache data of the local system through the protocol service of the local system protocol component instance to obtain business logic conversion data; De-service the service logic conversion data using an encoder of the local system protocol component instance to obtain de-service data; Passing the de-serviced data to the peer system protocol component instance through the protocol data interface based on the data interaction queue; Performing local business processing on the de-businessized data through a decoder of the peer system protocol component instance to obtain local businessized data; The protocol service of the peer system protocol component instance performs a service logic conversion on the local service data based on the static configuration data and dynamic cache data of the peer system to obtain service data in a target protocol format; Pushing the target protocol format service data to the peer system through the protocol service interface of the peer system protocol component instance; If the business data is PUSH behavior data, then the conversion operation process ends; If the service data is ACK behavior data, the feedback result sent by the opposite end system after receiving the service data in the target protocol format is processed in the reverse process of the conversion operation flow and then flows back to the local end system.

8. A data protocol conversion method according to claim 7, characterized in that: The data interaction queue is a bidirectional blocking queue based on first-in-first-out.

9. A data protocol conversion method according to claim 7, characterized in that: The framework queue of the data interaction queue includes an asynchronous queue and a synchronous channel. The local system protocol component instance actively pushes data through the asynchronous queue, and the opposite system protocol component instance passively receives the data pushed by the local system protocol component instance through the asynchronous queue. The local system protocol component instance actively requests data through the synchronous channel, and the opposite system protocol component instance passively responds to the request of the local system protocol component instance through the synchronous channel and sends data to the local system protocol component instance.

10. A data protocol conversion method according to claim 7, characterized in that: The calculation formula of the maximum number of queues m of the data interaction queue is as follows: m=n(n-1), n is the number of the standardized protocol components.

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