AppML stands for Application Modeling Language. It is developed for web application development. It extends HTML with data attributes and adds controllers to control the behavior of HTML data.

AppML is very easy to use understand and is used to make Single Page Application in an efficient way and quick manner. AppML focuses on fetching data to HTML applications from varying sources like javascript objects, json files, text files, xml files or database files.


About AppML :

AppML first version was developed by Jan Egil Refsnes in 1991 and it was based on HTTP request communication between web client and web server. In february 2015, W3Schools made AppML public by re-launching it as a new product.

The primary purpose of using Application Modeling Language (AppML) in application development is to facilitate the rapid creation, representation, and management of application structures, behaviors, and data.


AppML serves several key purposes :

Abstraction and Simplification : AppML allows developers to abstract complex application structures and behaviors into a more manageable and understandable format. It simplifies the representation of applications, making it easier to visualize, design, and communicate application architectures.

Rapid Prototyping and Development : It enables rapid prototyping by providing a structured way to model application components and their relationships. This facilitates quick iterations during the development process, allowing developers to create and test application models before the actual implementation.

Standardization and Consistency : AppML often follows a standardized syntax and structure, promoting consistency in application development across teams. This standardization helps in maintaining uniformity and coherence in the application models, reducing errors and enhancing collaboration.
Separation of Concerns : AppML allows for a clear separation of concerns between application structure, behavior, and data. By modeling these components separately, developers can focus on specific aspects of the application without getting entangled in the complexities of the entire codebase.

Ease of Maintenance and Updates : Applications modeled using AppML can be easier to maintain and update. Changes to the application can be made at the modeling level, and these changes can propagate throughout the application, ensuring consistency and reducing the chances of errors.

Cross-platform Compatibility : AppML can be designed to be platform-agnostic, allowing applications to be more easily adapted or deployed across different platforms or environments. This adaptability enhances the scalability of the application.

AppML is designed considering following concepts :

* AppML based application will be primarily an internet based application.

* It should use Internet Standards only for a web application i.e. HTML, CSS and JavaScript.

* It should be platform independent.

* It should be capable of handling application varying needs.

* It should be easy to understand and self-descriptive.

* It should be highly maintainable and easy to develop and should accomodate change easily.

* It should be future ready.

* Low Cost of development and maintainance.

* Facilitate Rapid and Agile Web Development.

* It is optimized for cloud computing.

* It is very fast and supports low bandwidth consumption.

* Follows MVC (Model View Controller) Architecture.

* Data layer can be completely separated from presentation layer.

* Highly scalable.

* Highly Testable.

* Easy to configure or reconfigure.

Application Modeling Language (AppML) plays a significant role in various stages of the software development lifecycle (SDLC), contributing in the following ways:

1. Requirement Analysis and Design Phase :

* Conceptualization : AppML aids in conceptualizing the application structure, behaviors, and data entities based on the requirements gathered.
* Prototyping : Developers use AppML to create initial application models, allowing stakeholders to visualize and validate the proposed design before actual development begins.


2. Development Phase :

* Guided Implementation : AppML provides a blueprint for developers to follow while coding, ensuring alignment with the design and reducing ambiguity.
* Efficiency : By having a structured model, development teams can work more efficiently, focusing on implementing specific features based on the defined AppML structures.


3. Testing Phase :

* Test Case Generation : AppML can guide test case creation, ensuring comprehensive coverage based on the defined application structures and functionalities.
* Validation and Verification : Testers can use the AppML specifications to verify if the application behaves as intended according to the initial models.
4. Deployment and Maintenance Phase :

* Ease of Deployment : AppML-based applications can be deployed more efficiently due to the clear specification of components and behaviors.
* Maintenance and Updates : Modifications and updates can be made more systematically by adjusting the AppML models, ensuring consistency and reducing the risk of errors during maintenance.


5. Collaboration and Documentation :

* Team Collaboration : AppML provides a common language for different teams (developers, designers, testers) to communicate and collaborate effectively throughout the SDLC.
* Documentation : AppML models serve as living documentation for the application, aiding in understanding its structure and facilitating future enhancements or modifications.


6. Scalability and Evolution :

* Scalable Models : AppML allows for scalable application models, enabling the application to evolve and adapt to changing requirements or technological advancements over time.

AppML, as an application modeling language, comprises various fundamental components or elements that collectively describe the structure, behavior, and data of an application. The specific elements may vary depending on the implementation or version of AppML, but here are some common fundamental components:

Entities : Entities represent the fundamental building blocks of the application. They can denote real-world objects, concepts, or data structures within the application domain.

Attributes : Attributes describe the properties or characteristics of entities. These can include properties such as name, type, size, and any other relevant details specific to an entity.

Relationships : Relationships define connections or associations between entities. They describe how different entities are related to each other within the application model.

Actions/Behaviors : Actions or behaviors refer to the functionalities or operations that entities can perform. They describe what an entity can do or how it can be manipulated within the application.

Events : Events represent occurrences or triggers that initiate specific actions or behaviors within the application. They define when and how certain actions or processes are activated.
Constraints and Rules : Constraints and rules establish conditions, limitations, or guidelines within the application model. These constraints may define validation rules, business logic, or other restrictions that entities must adhere to.

Views/UI Elements : Views or user interface elements describe how entities and their attributes are presented to users. They encompass the visual representation and interaction elements of the application.

Hierarchy and Structure : AppML often includes elements to represent hierarchies or structural relationships between entities. This could involve grouping entities or defining parent-child relationships.

Metadata and Annotations : Metadata and annotations provide additional information or context about elements within the AppML model. These can include descriptions, tags, or other metadata to enhance understanding or provide documentation.

Modules/Components : AppML may support the modularization or componentization of the application, allowing the model to be divided into smaller, reusable parts.

The syntax rules and conventions within AppML are designed to provide a structured and standardized way to define application models. While syntax specifics might vary based on the implementation or version of AppML, here are some common syntax rules and conventions:

1. Element Structure :

* Tags : AppML typically uses tags or elements enclosed within angle brackets < > to define components such as entities, attributes, relationships, etc.
* Naming Conventions : Elements are named according to specific conventions or guidelines, often using alphanumeric characters and underscores, and may have naming rules like starting with a letter.
* Hierarchical Representation : Syntax may support hierarchical representation using indentation, XML-like nesting, or other means to denote relationships or structures.


2. Attributes and Properties :

* Key-Value Pairs : Attributes and properties are often defined as key-value pairs within an element, separated by an equal sign or other designated separators.
* Datatypes : AppML may specify datatypes for attributes to denote the type of data they hold (e.g., string, integer, boolean).


3. Relationship Definitions :

* Relationship Tags : Relationships between entities are defined using specific relationship tags or elements, indicating the nature of the association (e.g., one-to-one, one-to-many).
* Role Naming : Roles within relationships might be named to identify the nature of the connection between entities.
4. Actions/Behaviors :

* Action Syntax : Actions or behaviors may be specified using specific syntax or keywords within entity definitions to describe functionalities or operations.
* Event Triggers : Syntax might include event triggers with specific markers or keywords to denote when actions are triggered.


5. Constraints and Rules :

* Constraint Definitions : Constraints or rules could be represented using specific syntax within entity or attribute definitions to enforce conditions or limitations.
* Validation Syntax : Syntax for validation rules might include expressions, conditions, or logic statements to validate data.


6. Comments and Documentation :

* Comment Syntax : AppML often allows comments using designated symbols or markers to annotate the code for readability and documentation purposes.
* Documentation Tags : Syntax may support documentation tags or markers to provide additional information about elements or models.


7. Modularity and Reusability :

* Module Definitions : Syntax may include mechanisms to define modules or components within the model for better organization and reusability.
* Import/Export Syntax : AppML might provide syntax for importing or exporting modules to facilitate reuse across multiple models or applications.

AppML provides a structured means to represent and organize data elements, enabling developers to model the structure, behavior, and relationships of the application components in a systematic and understandable format.

This structured representation aids in visualization, design, and communication of application architectures during the software development lifecycle.

AppML can offer advantages in various scenarios and types of applications where structured modeling and abstraction of application components are beneficial. Here are some scenarios where AppML can be particularly advantageous:

Complex Application Structures :

* Enterprise Applications : For large-scale enterprise applications with intricate data models and numerous interconnected components, AppML helps in modeling and managing the complexity.


Rapid Prototyping and Iterative Development :

* Prototyping : In scenarios where quick prototyping or iterative development is essential, AppML allows for the rapid creation and modification of application models, enabling faster iterations.


Data-Centric Applications :

* Data-Intensive Applications : Applications heavily reliant on data management and manipulation benefit from AppML's structured representation of data entities and relationships.


Multi-platform Applications :

* Cross-platform Applications : AppML's platform-agnostic nature facilitates the creation of applications that need to be deployed across different platforms, ensuring consistency in modeling.
Collaborative Development Environments :

* Team Collaboration : In environments with multiple developers or teams working on different parts of an application, AppML's standardized modeling language fosters collaboration and consistency.


Applications with Evolving Requirements :

* Agile Environments : AppML supports agility by allowing for easier adaptation to changing requirements or business needs, making it suitable for agile development methodologies.


Data-Driven Industries :

* Financial Systems, Healthcare, IoT : Industries where data integrity and relationships are critical, such as finance, healthcare, or IoT, benefit from AppML's ability to model complex data structures and constraints.


Maintainable Applications :

* Long-term Maintenance : Applications requiring long-term maintenance or updates benefit from AppML's structured models, simplifying the process of understanding and modifying the application over time.


API and Service Integration :

* API-driven Applications : Applications interacting with multiple APIs or services can utilize AppML to model interactions, facilitating integration and communication between different components.


Compliance and Regulations :

* Regulated Industries : In industries with strict compliance or regulatory requirements, AppML's ability to define constraints and rules aids in ensuring adherence to standards.

Integrating AppML into the development workflow involves several steps and considerations to effectively leverage its capabilities. Here's a guide on how to integrate AppML:

Requirement Gathering and Analysis : Begin by gathering and analyzing requirements for the application. Understand the data structures, behaviors, and relationships needed.

Modeling Phase : Create AppML models that represent the application's structure, entities, attributes, relationships, behaviors, and constraints. Use tools or text editors that support AppML syntax.

Collaboration and Review : Collaborate with stakeholders, developers, and other teams to review and refine the AppML models. Ensure clarity and alignment with the application requirements.

Version Control and Management : Use version control systems (e.g., Git) to manage AppML models. Maintain different versions to track changes and iterations made during the development process.

Development Implementation : Develop the application based on the AppML models. Use the models as a reference guide for coding the application's functionalities, ensuring alignment between the model and implementation.
Testing and Validation : Test the application against the AppML-defined models. Verify that the application's behavior aligns with the expected outcomes defined in the models. Use the models to create test cases.

Deployment and Maintenance : Deploy the application while ensuring that the deployed version corresponds to the finalized AppML model. Maintain the AppML models as living documentation for future reference and updates.

Tooling and Integration : Utilize tools or software that support AppML for seamless integration into the development workflow. Use IDEs (Integrated Development Environments) or dedicated AppML editors to streamline modeling and development.

Documentation and Communication : Document the AppML models comprehensively, explaining the structure, relationships, and behaviors defined. Communicate the models effectively among team members for better understanding and collaboration.

Adaptation and Iteration : Be ready to iterate on the AppML models as the application evolves or requirements change. Update the models to reflect any modifications in the application's structure or functionalities.

Using AppML for rapid application development offers several advantages that streamline the development process and accelerate the delivery of software solutions:

Abstraction and Simplification :  AppML abstracts complex application structures into a more manageable format, simplifying the representation of entities, relationships, and behaviors. This simplification aids in quick visualization and understanding of the application's design.

Rapid Prototyping and Iteration : AppML facilitates rapid prototyping by allowing developers to create and modify application models swiftly. It enables quick iterations and validations of design ideas before actual implementation, expediting the development process.

Structured Development Approach : By providing a structured modeling language, AppML promotes a systematic approach to application development. Developers can follow defined models, ensuring consistency and reducing errors during implementation.

Enhanced Collaboration and Communication : AppML serves as a common language for developers, designers, and stakeholders, fostering better collaboration and communication. It allows teams to align on application structures and functionalities more efficiently.

Agility and Flexibility : AppML supports agile development methodologies by enabling easier adaptation to changing requirements. It allows for quick modifications or additions to the application model, accommodating evolving needs.
Standardization and Consistency : AppML encourages standardization in modeling practices across teams or projects. This consistency simplifies maintenance, reduces learning curves, and promotes reusability of models or components.

Efficient Testing and Validation : Application models created using AppML serve as a basis for generating test cases and validating the application's behavior. This streamlined testing process saves time and ensures comprehensive test coverage.

Reduced Development Time and Costs : The ability to quickly model application components, relationships, and behaviors in AppML results in faster development cycles. Consequently, this can lead to reduced development time and associated costs.

Modularity and Reusability : AppML allows for modularization of application components, enabling reusability across different projects or within the same project. Modular models can be employed in various contexts, enhancing efficiency.

Documentation and Maintenance Ease : AppML models serve as living documentation for the application, aiding in understanding the structure and behaviors. This documentation simplifies maintenance and updates, especially for long-term projects.

AppML manages relationships between different components or entities through specific syntax and conventions designed to define and describe these connections. Here's how AppML typically handles relationships:

Defining Relationships : AppML allows developers to explicitly define relationships between entities using designated syntax or tags. For instance, tags like <relationship> or <association> might be used to denote relationships.

Cardinality and Multiplicity : Relationships in AppML often specify cardinality or multiplicity, indicating the number of instances of one entity that are associated with another. It can define one-to-one, one-to-many, or many-to-many relationships.

Role Naming and Directionality : AppML permits role naming within relationships to clarify the role each entity plays in the relationship. It can specify the directionality of the association, elucidating the nature of the connection.

Attributes within Relationships : AppML might allow for the inclusion of attributes or properties within relationships, providing additional information or constraints specific to the association between entities. Hierarchical Representation : Relationships can be structured hierarchically within AppML models, showcasing the connections between various entities and their interdependencies.

Behavioral Definitions : Relationships in AppML can incorporate behavior definitions, describing actions or behaviors associated with the relationship itself, such as cascading updates or deletions.

Validation and Constraints : AppML may support the inclusion of constraints or rules within relationships to ensure data integrity, enforce referential integrity, or define conditions that must be met for the relationship to exist.

Visualization and Documentation : AppML models can provide a visual representation of relationships, aiding in understanding the connections between entities. Additionally, relationships are documented within the model for reference and clarity.


AppML's approach to handling relationships emphasizes clarity, specificity, and explicit definition of associations between different components or entities within an application model. This structured representation enables developers to accurately capture and depict the interconnectedness of various elements within the application, facilitating better understanding and management of relationships during the development process.

Several tools and software can complement the use of AppML in application development, aiding in modeling, validation, integration, and more. Some commonly used tools include:

Text Editors or IDEs (Integrated Development Environments) :

* Visual Studio Code : Often used due to its extensibility and support for various languages, including XML-based languages like AppML.
* Sublime Text, Atom : Lightweight text editors with plugins/extensions for syntax highlighting and code completion for AppML.


AppML-Specific Editors or Modeling Tools :

* Enterprise Architect : Offers AppML support for modeling and visualization of application structures and relationships.
* Lucidchart, draw.io : Diagramming tools that allow the creation of AppML-like models for visualization.


Version Control Systems :

* Git, SVN : Essential for managing AppML models, tracking changes, and enabling collaboration among team members.


Validation and Testing Tools :

* XML Validators : Tools that validate AppML syntax against XML standards, ensuring compliance and correctness of the models.
* Custom Validation Scripts/Tools : Often created internally to validate AppML-specific rules or constraints beyond standard XML validation.
Documentation Tools :

* Markdown Editors : Used for creating documentation related to AppML models, explaining structures, relationships, and constraints.
* Confluence, Wiki Software : Platforms for collaborative documentation and knowledge sharing around AppML models and their usage.


Data Integration and API Tools :

* Postman, SOAP UI : For testing APIs and integrating them into applications modeled with AppML.
* Data Integration Platforms : Tools facilitating data exchange and integration with applications using AppML-defined structures.


Model Repository or Database Tools :

* Model Repositories : Platforms or databases to store and manage AppML models, allowing versioning and easy access.
* Document Databases : For storing and retrieving AppML models in a structured manner.


Custom Development Frameworks :

* Custom Libraries or Frameworks : Developed in-house to extend AppML's functionality or integrate it more seamlessly into specific development environments.

Whenever AppML performs any action, it sends a signal via $application object to the controller. $application.message property describes the application state and we can act accordingly.

For example :

function studentController($appml) {
   if ($appml.message == "ready") {alert ("Application loaded.");}
}​

Messages : Following are the kind of messages that AppML sends to controller.

ready : When AppML is initialized and is ready to load data, then ready message is sent.

loaded : When AppML is fully loaded and is ready to display data, then loaded message is sent.

display : display message is sent before AppML is to display a data.

done : When AppML displayed data, then done message is sent.
AppML properties : Following is the list of important AppML properties.

$appml.message : Represents the current state of AppML Application.

$appml.display.name : Represents the name of the data item about to be displayed.

$appml.display.value : Represents the value of the data item about to be displayed.

$appml.error.number : Error number

$appml.error.description : Error description

While AppML itself does not execute or directly interface with other languages in the same way a programming language might, it serves as a structured representation that can guide the development process and foster interoperability by aligning different parts of the application ecosystem with a common model. Integration with other languages or frameworks often involves interpretation, code generation, or adherence to standardized formats based on the AppML-defined structures.

Scalability in applications designed using AppML can be ensured by adopting strategies that accommodate growth, handle increased loads, and support evolving requirements. Here's how to ensure scalability when designing applications with AppML:

Modular Design : Employ a modular design approach within AppML models. Break down the application into smaller, reusable modules that can scale independently. This allows for easy expansion or modification of specific modules without impacting the entire application.

Efficient Data Modeling : Design the data model in AppML to be scalable. Consider factors such as normalization, denormalization, indexing, and partitioning to optimize data storage and retrieval as the application grows.

Horizontal Scaling Consideration : Ensure that the AppML model supports horizontal scaling, allowing the application to scale across multiple instances or servers. Design entities and relationships in a way that facilitates distributed computing and load balancing.

Performance Optimization : Optimize AppML models for performance by reducing unnecessary complexity, optimizing queries, and ensuring efficient data access. Consider caching mechanisms and efficient indexing strategies for improved performance.

Scalable Architecture Patterns : Adopt scalable architecture patterns, such as microservices architecture or service-oriented architecture (SOA), where different components can be scaled independently based on demand. Elasticity and Auto-Scaling : Implement mechanisms for automatic scaling based on demand. Utilize cloud-based services that offer auto-scaling capabilities to dynamically adjust resources as needed.

Resource Monitoring and Management : Implement monitoring tools to track resource usage, application performance, and bottlenecks. Utilize these insights to optimize and scale resources accordingly.

Load Testing and Capacity Planning : Conduct load testing to assess the application's performance under different load conditions. Use capacity planning to anticipate future growth and ensure the infrastructure can handle increased loads.

Flexible and Extensible Models : Design AppML models to be flexible and extensible, accommodating changes and additions to the application's functionality without significant restructuring.

Future-Proofing Strategies : Anticipate future needs and incorporate scalability considerations into the initial design. Plan for future enhancements and ensure the AppML models can accommodate those changes seamlessly.

AppML application allows to control the UI using the controller function. appml-controller tag provides the name of the javascript function which acts as a controller. AppML application may or may not have a controller.

Syntax :

<table appml-controller="studentController"></table>​

AppML sends messages to controller function via an application object denoted by $appml. Based on the properties of $appml we can perform various types of operations on HTML content.

Following are some of the important examples :

* Initialize data

* Update application data

* Input/output handling

* Data validation

* Data summarization

* Error handling

* Application start/stop

AppML Model describes an application. It is a JSON based format and we can define following functionalities.

Syntax :

<table appml-data="local?model=model_students"></div>​

Here model_students.js is the AppML data model file.

model_students.js

{
"rowsperpage" : 10,
"database" : {
   "connection" : "localsql",
   "sql" : "SELECT studentName, class, section FROM Students",
   "orderby" : "StudentName"
},
"filteritems" : [
   {"item" : "studentName", "label" : "Student"},
   {"item" : "class"},
   {"item" : "section"}
],
"sortitems" : [
   {"item" : "studentName", "label" : "Student"},
   {"item" : "class"},
   {"item" : "section"}
]
}​

Following are the common uses of AppML models :

* Define database connections to MySQL, Sql Server, MS Access and Oracle.

* Define connection to access files like JSON, XML, csv based text file.

* Define SQL statements for CRUD (Create, Read, Update, Delete) operations.

* Apply Filter/Sorting restrictions on table.

* Define data types, data formats and restrictions on them.

* Apply security on application users. Define user groups.

Methods : Following are the AppML methods.

* new AppML() : Used to create a new AppML object.
* appml("name") : Used to return the appml object with the specified name.
* displayMessage(text) : Used to display a specified message.
* getData() : Used to fetch application data.
* run() : Used to run application object.
* setError(code, description) : Used to set an error with code and description.



Properties : Following are the AppML properties.

* appName : Name of the application, id of the container
* container : Container object
* controller : Controller object
* data : data object.
* dataSource : data source.
* displayType : Application Type, form or list
* message : message object
* error : error object
Data Object Properties : Following are the AppML data object properties.

* data.model : application data model.
* data.records : application records.


Form Methods : Following are the AppML form methods.

* newRecord() : Used to reset the current form.
* saveRecord() : Used to save the current record.
* deleteRecord() : Used to delete the current record.
* closeForm() : Used to close the current form.


Filter properties : Following are the AppML filter properties.

* orderBys : An array of order by field names.
* orderByDirections : An array of order by directions .
* queryFields : An array of query field names.
* queryValues : An array of query values.
* queryTypes : An array of query types.