CN1968154A - System and method for service expansion using plug - Google Patents

Abstract

The invention relates to a system for using plug to expand service and relative method, wherein it can improve flexibility and make maintenance simply; the invention independently manage plugs and setting document, while all plugs and setting documents are stored in subdirectory of appointed directory; at the start of system, reading the setting documents of all plugs to obtain the relation between expansion, plug and dynamic base of expand point, and the dependent relation with plugs. When needs to expand, it will load and expand relative plugs and relative dynamic base.

Description

System and method for business extension using plug-ins

technical field

The invention relates to the communication field, in particular to the plug-in technology in the network management system.

Background technique

Now almost all industries and most businesses of enterprises rely on computer application systems, which leads to a sharp expansion of the capacity of the network as the basic platform for data transmission, and a great increase in the content and complexity of the network.

In order to facilitate the maintenance of the network, on the one hand, it is necessary to ensure the reliability of network transmission through stable and reliable transmission equipment, and on the other hand, it is necessary to use some management tools to ensure the monitorability and maintainability of the network. With the development of network applications, in order to ensure the normal operation of network systems with increasingly complex structures and larger scales, in addition to relying on the reliability of the network equipment itself and the network architecture, network management is a key link. The quality of management will directly affect the quality of network operation. Network management is already a key factor to ensure the normal operation of computer networks, especially large computer networks. Use the network management system to automatically monitor and manage the network, view the status of the entire network in real time, detect possible bottlenecks in network performance, and perform automatic processing or alarm display to ensure efficient and reliable operation of the network.

The composition of the network management system software modules is shown in Figure 1. The network management system software includes two parts: network management platform and domain network management extension. Among them, the network management platform is responsible for realizing the public part of the network management functions; domain network management expansion is carried out on the basis of the network management platform for secondary development and implementation, and provides domain business modules based on the network management platform expansion for different fields that support the specific management objects and services in this field .

The network management platform is further divided into the bottom management core and the public business part. The underlying management core implements the underlying core functions of the network management service, including modules such as network management service control, network element definition and management, and network element adaptation layer management; public services provide the common part of the common services of the network management on the underlying core functions Implementation, including public safety management, public topology management, public alarm management and other modules.

The alarm object generated by the public alarm management module is an important output of the network management system, describing the software and hardware faults that occur during the operation of the network system. The alarm object can notify the user of the type of problem in the network device and the location of the problem, and its generation source includes the hardware device and software monitoring system in the network. Alarm objects can be classified according to different standards. For example, they can be divided into event alarms, fault alarms, and recovery alarms according to their nature; they can be divided into emergency alarms, important alarms, general These are power supply alarms, computer room environment alarms, SS7 alarms, digital trunk alarms, hardware alarms, software alarms, and operation alarms. The alarm object can be composed of various information. For example, the main components of the alarm object generated by the network management system used in a typical telecommunication network can include: product type, the product number used to identify the alarm equipment, which can distinguish fixed network, transmission, Mobile, intelligent and other products; device type, used to identify the type number of the alarm device; alarm number, used to identify the number of the alarm type; alarm type, used to describe the nature of the fault, which can distinguish fault, recovery or event; alarm level, It is used to describe the severity of the alarm; the alarm category is used to describe the source of the fault, which can distinguish power alarms, computer room environment alarms, and No. 7 signaling alarms; alarm name is used to identify the name of the alarm; serial number is used to identify The serial number of alarm generation and arrival sequence; date, used to identify the date when the alarm occurred; time, used to identify the time when the alarm occurred; location parameters, used to store fault location information, describing the specific location of the problem; explanation information, Information used to explain the cause and location of the alarm; repair suggestion, used to describe how to fix the alarm to help users quickly solve the problem; link type, used to identify the link type number to which the fault belongs.

The public alarm management module provides the core implementation of the alarm processing process. The schematic diagram of processing the alarm data based on the public alarm management module is shown in Fig. 2 .

In Fig. 2, the network element device sends the alarm data generated by itself to the network management system server through the network, and the network management system server analyzes and processes the alarm, and then sends the processed alarm data to the network management user interface. Users can observe the alarms of network element devices from the network management user interface, and perform operations such as query and browsing on these alarms.

In the process of expanding the public alarm management module, in many cases, business functions need to be expanded. For example, a network management product in a certain field (referred to as "domain network management") may need to analyze the relationship between an alarm and a key customer, and fill in the name of the key customer affected by the alarm in the alarm object. In this way, the public alarm management module needs to complete the following two expansions: 1) Add the field of "key customer affected by the alarm" in the alarm object; 2) insert the logic code of secondary development, such as resource model, to analyze the relationship between the alarm and the big customer relationship, and modify the "Alarm Affected Major Customers" field of the alarm object. The second extension requires the public alarm management module to provide a plug-in mechanism to embed the business logic code of the domain network management into the alarm processing process.

The plug-in implements certain features and is published in the form of a dynamic library, which can realize the dynamic upgrade of the business and facilitate the use and development of users. Generally speaking, the configuration files of plug-ins use the Extensible Markup Language (Extensible Markup Language, referred to as "XML") file format. Since XML is a mature label language, the use of XML file format makes the configuration information standardized and standardized, and it is easy to use in On different platforms and languages; a dynamic library is a library file that can be dynamically loaded when the system is running, and it is a DLL type file under the Windows (Windows) system.

When the existing technical solution needs to expand the business, the configuration file of the public platform is modified according to the business expansion plug-in to realize the loading of the plug-in. The configuration information of all available plug-ins is stored in the configuration file of the public platform, and the configuration file of the public platform manages the configuration information of these plug-ins in a centralized manner.

Specifically, in the existing technical solution, when business expansion is required, the configuration of the corresponding process of the extended business is added to the configuration file of the public platform, a dynamic library containing the business logic is formulated, the dynamic library is loaded during initialization, and During the execution process, the logic code corresponding to the extended service is executed.

Because the configuration file is centrally managed for the configuration information, the configuration file is updated centrally, that is, the configuration file of the public platform needs to be modified every time a plug-in is added for business expansion.

The root cause of the insufficiency of the existing technical solutions lies in the centralized update of the configuration files. This centralized update of the configuration files will bring the following disadvantages:

First, the configuration files of the existing technical solution are updated centrally, but since the business extension points that need to be added cannot be predicted, it is necessary to continuously add content to the configuration files of the public platform, which makes the implementation complicated;

Second, the existing technical solutions need to modify the configuration file of the public platform every time a service extension point is released, so no matter whether the domain network management needs the service expansion, it is necessary to merge the configuration files of the public platform used in the domain network management. Business expansion cannot be achieved by directly downloading plug-ins, and the existing technical solutions cannot pre-extend the input required by the business logic, so that the business logic code also needs to maintain its own configuration files, which have caused difficulties in upgrading;

Third, when there are many business expansion points of the domain network management in the existing technical solutions, there is no general mechanism to formulate the dependencies between dynamic libraries, resulting in a decrease in the robustness and scalability of the system operation;

Fourth, the prior art solution needs to load all the dynamic libraries in the configuration file when starting. When there are many plug-ins, it will cause the system to start up for a long time. If some dynamic libraries do not need to be loaded, the configuration file needs to be modified to prohibit its loading. The flexibility of plug-in loading is not high;

Fifth, in the existing technical solution, when the plug-in itself needs to develop its own business expansion and allow others to expand again, there is no unified mechanism, and each plug-in needs to maintain a set of mechanisms independently, making maintenance more troublesome.

Contents of the invention

In view of this, the main purpose of the present invention is to provide a system and method for using plug-ins to expand services, which improves the flexibility of plug-in loading and makes maintenance easier.

To achieve the above purpose, the present invention provides a system for business expansion using plug-ins, including:

The business module is used to insert the logic code of the plug-in at the extension point to realize business expansion;

The plug-in management module is used to read the configuration file of each plug-in to generate a plug-in resource list when the system is started, and when the business module needs to initialize an extension, load the plug-in and its plug-in required by the extension that needs to be initialized according to the plug-in resource list. Dependent on other plugins.

Wherein, the configuration file and other related files of the plug-in are placed in a preset plug-in directory and the configuration file is at the top level of the plug-in directory, which is a subdirectory of the specified plug-in root directory.

In addition, in the system, the configuration file contains information related to the loading of the plug-in, and the configuration file uses Extensible Markup Language.

In addition, in the system, the plug-in resource list includes an extension point registry stored by extension point items and a plug-in table stored by plug-in items.

In addition, in the system, the extension point registry is stored in a tree structure, the first layer of sub-nodes is the extension point, the second layer of sub-nodes is the extension corresponding to the extension point, and the third layer of sub-nodes The point is the attribute information of the extension.

In addition, in the system, the plug-in table is stored in sub-entries, and each entry stores information related to one plug-in.

In addition, the system is applied in the network management platform.

The present invention also provides a method of using a plug-in for business expansion, which includes the following steps:

A obtains plug-ins and configuration files;

When B starts, read the information in all the configuration files and generate a plug-in resource list;

When the extension needs to be initialized, C loads the plug-in required by the extension to be initialized and other plug-ins it depends on according to the plug-in resource list.

Wherein, the configuration file and other related files of the plug-in are placed in a preset plug-in directory and the configuration file is at the top level of the plug-in directory, which is a subdirectory of the specified plug-in root directory.

In addition, in the method, the plug-in resource list generated in the step B includes an extension point registry stored according to the extension point item and a plug-in table stored according to the plug-in item.

In addition, in the method, the configuration file used in the step A contains information content related to the loading of the plug-in, and its type is an extensible markup language file.

Through comparison, it can be found that the main difference between the technical solution of the present invention and the prior art is that the plug-ins and their configuration files are managed independently, and all plug-ins and their configuration files are stored in subdirectories of the specified directory, and read when the system starts The configuration files of all plug-ins obtain the extension of the extension point, the corresponding relationship between the plug-in and the dynamic library, and the dependencies between the plug-ins. Only when the extension needs to be used, the plug-in related to the extension and the dynamic library of the plug-in that it depends on are loaded. . The so-called independent management plug-in and its configuration file in the present invention take the plug-in and its configuration file as a unit, each unit is managed independently, and each unit is stored in the subdirectory of the specified directory respectively, not the plug-in and configuration file Its configuration files are managed separately or placed in different subdirectories.

The difference in this technical solution has brought more obvious beneficial effects, that is, first, using the solution of the present invention, since there is no need to modify the configuration file of the public platform, it can adapt to the needs of insertion point customization that may occur in the future, and the implementation is simple ;

Second, the solution of the present invention can independently publish plug-ins for business logic expansion, without modifying the configuration files of the network management platform, and can simply realize business expansion by copying and deleting;

Thirdly, since the solution of the present invention independently manages the plug-in and its configuration file, the dependencies of the plug-in can be clearly specified, thus greatly enhancing the robustness and scalability of the system operation;

Fourth, the plug-in of the present invention can be loaded during use, which improves the flexibility of plug-in loading and greatly reduces system startup time and resource consumption during operation;

Fifth, the solution of the present invention is also applicable to the business expansion of the plug-in itself, which greatly simplifies the realization of system function expansion, and is beneficial to the long-term evolution of the system and the reduction of costs.

Description of drawings

Fig. 1 is the composition diagram of network management system software module;

Fig. 2 is a schematic diagram of processing alarm data based on the public alarm management module;

Fig. 3 is a schematic diagram of system composition using plug-ins for business expansion according to a preferred embodiment of the present invention;

Fig. 4 is a flow chart of using plug-ins to extend services according to a preferred embodiment of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings.

The solution of the present invention independently maintains a configuration file for each plug-in, and the plug-in and its configuration file are stored in the specified path of the system. When the system starts, the configuration file of each plug-in is read separately under the specified path to obtain the insertion point and dependency relationship. The plug-in configuration information included in the plug-in, when the plug-in needs to be used, the corresponding plug-in is loaded according to the configuration information of the plug-in. In this way, the installation and deletion of the plug-in can be simply completed by copying and deleting in the specified path.

In order to illustrate the solution of the present invention more clearly, the following description will be made in conjunction with the preferred implementation modes of the present invention.

The system composition of using plug-ins for business expansion according to a preferred embodiment of the present invention is shown in FIG. 3 .

The system for business expansion using plug-ins includes: a business module 10 for publishing extension points and a plug-in management module 20 .

The business module 10 that publishes the extension point is used to provide the interface of the extension point and the document including the interface meaning and implementation constraint description, inserting the logic code of the plug-in into the extension point to realize the service extension. Among them, the extension point is the position where the logic code can be inserted. When the business module releases the extension point, it needs to publish the interface of the extension point and the document including the interface meaning and implementation constraint description. In a preferred embodiment of the present invention, the service module 10 issuing extension points is the public alarm management module in the network management platform.

Those skilled in the art can understand that, according to the published extension point interfaces and description documents, developers can use extension points to implement extensions of business functions through plug-ins. How to implement the plug-in is not the key point of the present invention, but to facilitate the understanding of the solution of the present invention, here is a brief description of the generation, organizational structure and content of the plug-in related files. In a preferred embodiment of the present invention, the plug-in developer implements the plug-in class according to the public interface, implements the interface of the extension point according to the document of the extension point, and provides instantiation of the extension in the factory method of the plug-in, and then compiles it to generate Dynamic libraries, and finally, plugin developers write plugin configuration files and organize them and plugin-related files in a plugin directory. Among them, the plug-in class mainly includes the initialization method of the plug-in and the implementation of the factory method. The type of configuration file is an XML file. In a preferred embodiment of the present invention, it is called plugin.xml, and the configuration information it contains is divided into public configuration information and private configuration information. The public configuration information described in this file includes: the attributes of the plug-in , such as the path of the dynamic library, other dependent plug-ins, etc.; extension point information, which specifies which extension point the current plug-in extends. In addition, for the purpose of simplifying file organization and reading, in a preferred embodiment of the present invention, the configuration file is placed at the top level of the plug-in directory.

The plug-in-related documents referred to in the present invention include configuration files of the plug-in, dynamic library files, and possible resource files, description files, and the like.

It should be noted that although configuration files and other plug-in-related files are organized in a plug-in directory in a preferred embodiment of the present invention, it can be understood that configuration files and other plug-in-related files can also be organized in other agreed ways, Does not affect the essence of the present invention.

The plug-in management module 20 is used to manage all plug-ins. When the system starts, the configuration file of each plug-in is read to generate a plug-in resource list, and when a plug-in needs to be used, the plug-in and its dependent plug-ins are loaded according to the plug-in resource list. Among them, the plug-ins are stored in the plug-in directory. In order to facilitate the management of all plug-ins, all the plug-in directories are placed in a specific directory. A plug-in is to copy the plug-in directory where the plug-in is located to $PLUGIN_ROOT, and deleting a plug-in is to move the plug-in directory where the plug-in is located from $PLUGIN_ROOT. Those skilled in the art understand that the plug-in directory can also be placed in multiple directories, which does not affect the essence of the present invention.

In a preferred embodiment of the present invention, the plug-in management module 20 further includes: an extension point registry 21 , a plug-in table 22 and a plug-in loading tool 23 .

Among them, the extension point registry 21 stores information such as all extension points, extensions corresponding to the extension points and their attributes, etc., and the extensions of the current extension point and the plug-ins corresponding to these extensions are obtained by querying when the service module 10 issuing extension points initializes the extension. In a preferred embodiment of the present invention, the extension point registry is represented in a tree, the first layer of sub-nodes are all extension points of the system, the sub-nodes of each extension point are the extensions configured in the configuration file, each extension Sub-nodes are extended attributes, and extended attributes include public and private attributes. Among them, public attributes include: extension identification (ID), extension class name, and extension plug-in name; private attributes are the input required by the extension itself, and the extension Clicking on the registry 21 is only for access, but does not understand its meaning.

The plug-in table 22 is used to store IDs of all plug-ins, dependencies, names of dynamic libraries that need to be loaded, class names of plug-ins, and some input required by the plug-ins themselves. The plug-in dependencies of the plug-in are queried according to the plug-in information output by the extension point registry 21. Relationships get the plugins that need to be loaded. In a preferred embodiment of the present invention, the plug-in table includes a plurality of entries, and each entry contains some attributes of the plug-in corresponding to the entry read from the configuration file, including public attributes and private attributes. Among them, the public attributes include: the ID used to uniquely identify the plug-in, the dependency list of the plug-in, the dynamic library that the plug-in needs to load, and the class name of the plug-in; the private attribute is the input required by the plug-in itself, and the plug-in table 22 is only for access and does not need to be understood its meaning.

For ease of description, the extension point registry 21 and the plug-in table 22 are collectively referred to as a plug-in resource list. It can be understood that since the plug-in resource list of the present invention clearly describes information such as the extension point, the relationship between the extension and the plug-in, and the dependencies between the plug-ins, it can be used only when the extension is needed according to the plug-in resource list. The query results load the corresponding plug-ins, and it is not necessary to load all plug-ins when the system is initialized, thus saving system startup time.

The plug-in loading tool 23 is used to load and initialize the dynamic library of the corresponding plug-in according to the information of the plug-in to be loaded outputted by the plug-in table 22 . It can be understood that after the plug-in loading tool 23 loads the plug-in module to which the extension belongs, the extended instance can be obtained through the factory method of the plug-in, that is, the method for generating a plug-in instance, and the class name of the extension, so as to realize business expansion. This part The implementation is exactly the same as the prior art solution, and will not be described in detail here. In a preferred embodiment of the present invention, the plug-in instance is also stored in the extension node of the registry, and the extension reference is returned.

It can be understood that, with the above-mentioned system using plug-ins for business extension, the business module 10 that develops the extension point can be used for extension. It can also be understood that, based on the system of using plug-ins for business expansion of the present invention, plug-ins for secondary development can also use the system to publish extension points, which facilitates the overall expansion of the system.

Cooperating with the above-mentioned system using plug-ins for business expansion, the present invention also provides a method for using plug-ins for business expansion. The process of using plug-ins for business expansion according to a preferred embodiment of the present invention is shown in FIG. 4 .

First enter step 410, obtain the plug-in directory including the configuration file and the dynamic library and store it in the specified root directory of the plug-in. Wherein, the type of the configuration file is an XML file. In a preferred embodiment of the present invention, it is named plugin.xml, and the configuration information included is divided into public configuration information and private configuration information. The public configuration information described in this file includes: Attributes, such as the path of the dynamic library, other dependent plug-ins, etc.; extension point information, which specifies which extension point the current plug-in extends. In addition, for the purpose of simplifying the organization and reading of files, in a preferred embodiment of the present invention, the configuration files are placed at the top level of the plug-in directory. Among them, the dynamic library is for the plug-in developer to implement the plug-in class according to the public interface, realize the interface of the extension point according to the document of the extension point, and provide the instantiation of the extension in the factory method of the plug-in, and then generate it after compiling. In order to facilitate the management of all plug-ins, all plug-in directories are placed in a specific directory. In a preferred embodiment of the present invention, this directory is the root directory of the plug-in, and the name is $PLUGIN_ROOT. To install a plug-in is to copy the plug-in directory where the plug-in is located. To $PLUGIN_ROOT, deleting a plugin is to move the plugin directory where the plugin is located from $PLUGIN_ROOT. Those skilled in the art understand that the plug-in directory can also be placed in multiple directories, which does not affect the essence of the present invention.

Then enter step 420, read information in all configuration files under the root directory of the plug-in when the system starts, and generate a plug-in resource list. Wherein, the plug-in resource list includes an extension point registry and a plug-in table. The extension point registry stores information such as all extension points, the extensions corresponding to the extension points and their attributes. When the business module that publishes the extension points initializes the extension, the extensions of the current extension points and the plug-ins corresponding to these extensions are queried. In a preferred embodiment of the present invention, the extension point registry is represented in a tree, the first layer of sub-nodes are all extension points of the system, the sub-nodes of each extension point are the extensions configured in the configuration file, each extension Sub-nodes are extended attributes, which include public and private attributes. Among them, public attributes include: extension ID, extension class name, and extension plug-in name; private attributes are the input required by the extension itself, and the extension point registry Only access, do not understand its meaning. The plug-in table is used to store IDs of all plug-ins, dependencies, names of dynamic libraries to be loaded, class names of plug-ins, and some inputs required by the plug-ins themselves. According to the plug-in information output by the extension point registry, the dependencies of the plug-in are queried. Plugins to load. In a preferred embodiment of the present invention, the plug-in table includes a plurality of entries, and each entry contains some attributes of the plug-in corresponding to the entry read from the configuration file, including public attributes and private attributes. Among them, the public attributes include: the ID used to uniquely identify the plug-in, the dependency list of the plug-in, the dynamic library that the plug-in needs to load, and the class name of the plug-in; the private attribute is the input required by the plug-in itself, and the plug-in table is only for access and does not understand other significance.

Then enter step 430, the service module publishing the extension point queries the plug-in resource list when initializing the extension. Wherein, in this step, the plug-ins related to the extension of the extension point and the plug-ins that depend on them can be obtained.

Then enter step 440 , judge whether the plug-in related to the extension has been loaded according to the query result in step 430 , if yes, enter step 460 , otherwise directly enter step 450 . Wherein, the system can know whether the plug-in has been loaded by querying the record in the plug-in resource list.

In step 450, extension-related but not yet loaded plug-ins are loaded. It can be understood that since the plug-in resource list of the solution of the present invention clearly describes information such as extension points, the relationship between extensions and plug-ins, and the dependencies between plug-ins, it can be used only according to the query results of the plug-in resource list when the extension needs to be used. Load the corresponding plug-ins, and do not need to load all plug-ins when the system is initialized, which can save system startup time.

In step 460, use the extension to obtain an instance of the extension and update the plug-in resource list. In a preferred embodiment of the present invention, the plug-in instance is stored in the extension node of the extension point registry, and the reference of the extension is returned.

Although the present invention has been illustrated and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the present invention. The spirit and scope of the invention.

Claims (11)

1. a system that uses plug-in unit to carry out professional expansion is characterized in that, comprises:

Business module is used for inserting at extension point the professional expansion of logical code realization of plug-in unit;

The plug-in management module, be used for when system start-up, reading respectively the configuration file generation plug-in resource tabulation of each plug-in unit, when described business module needs the initialization expansion, load the required plug-in unit of the initialized expansion of needs and other plug-in unit of dependence thereof according to this plug-in resource tabulation.

2. use plug-in unit according to claim 1 carries out the system of professional expansion, it is characterized in that, the top layer that other associated documents of described configuration file and described plug-in unit place the plug-in unit catalogue that sets in advance and described configuration file to be in this plug-in unit catalogue, the subdirectory of the plug-in unit root that this plug-in unit catalogue is appointment.

3. use plug-in unit according to claim 1 carries out the system of professional expansion, it is characterized in that, comprises in the described configuration file with described plug-in unit to load relevant information, and described configuration file uses extend markup language.

4. use plug-in unit according to claim 1 carries out the professional system that expands, and it is characterized in that, described plug-in resource tabulation comprises according to the extension point registration table of extension point subitem storage and the plugin table of storing according to the plug-in unit subitem.

5. use plug-in unit according to claim 4 carries out the system of professional expansion, it is characterized in that, described extension point registration table is stored with tree structure, its ground floor child node is an extension point, second layer child node is the expansion of described extension point correspondence, and the 3rd straton node is the attribute information of described expansion.

6. use plug-in unit according to claim 4 carries out the system of professional expansion, it is characterized in that, described plugin table is divided the list item storage, the relevant information of a described plug-in unit of each described list item storage.

7. carry out the system of professional expansion according to each described use plug-in unit in the claim 1 to 6, it is characterized in that described system applies is in network management platform.

8. a method of using plug-in unit to carry out professional expansion is characterized in that, comprises following steps:

A obtains plug-in unit and configuration file;

B reads the information in all described configuration files when starting and generates the plug-in resource tabulation;

When C expands in the needs initialization, load the required plug-in unit of the initialized expansion of needs and other plug-in unit of dependence thereof according to described plug-in resource tabulation.

9. use plug-in unit according to claim 8 carries out the method for professional expansion, it is characterized in that, the top layer that other associated documents of described configuration file and described plug-in unit place the plug-in unit catalogue that sets in advance and described configuration file to be in this plug-in unit catalogue, the subdirectory of the plug-in unit root that this plug-in unit catalogue is appointment.

10. use plug-in unit according to claim 8 carries out the method for professional expansion, it is characterized in that the described plug-in resource tabulation of described step B generation comprises according to the extension point registration table of described extension point subitem storage and the plugin table of storing according to described plug-in unit subitem.

11. the method that each described use plug-in unit carries out professional expansion in 10 according to Claim 8, it is characterized in that, comprised in the configuration file that described steps A is used and the relevant information content of described plug-in unit loading, its type is an extensible markup language document.

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