# Concepts


GUI models in DIME are structural declarations of a user interface, including basic control structural components and data-bindings to components. One of the main policy is the support for massive reuse, since DIME is designed for rapid prototyping and agile development.

In the following the data and event-driven concepts regarding to the core components and directives are described. The GUI models provide a multitude of basic components for accepting user input and displaying data, advanced components and various elements to create a unique user interface. In addition to this, every component is highly customizable to personalize the individual look and feel of the page at runtime.

# Data Flow

The GUI model is exclusively data-driven, which means that no control-flow is available. Only data changes result in a modification of the viewable page. The life-cycle of a GUI model starts with a rendering, including the injection of initially specified data. Similar to the process models, the GUI models take usage of a data context as well, which can be used analogous. In contrast to the processes the GUI models cannot receive data from output ports of a start node. The initially needed data has to be specified as an input in the properties of a variable in the data context. Every variable, which is specified as an input, will result in an Input Port of the corresponding GUI SIB. Depending on the received data and the Directives of the GUI, the rendering is done at runtime. read more

# Build-In Template Components

The GUI model of DIME is used to describe the declarative structure of the rendered page. This user interface structure is called template. The template can be build up using different components which represent common parts of a user interface like tables, forms with input fields and parts to render content. The different components can be nested in each other to customize the page and create an unique styling. The available components in the GUI models are divided into multiple groups, according to different requirements of a user interface. The succinct groups will now be introduced.

# Grid System

The grid system provides the ability to place the components in an entirely tunable layout. To align the components in a template, a row and column based grid system is provided. Every row can be subdivided in at most twelve columns, which can also be vertically redivided by additional rows. A particular column can be scaled in its relative width, to fit e.g. the full, half or quarter row width. At runtime the relative grid system is used in a responsive way to adjust the template components to any page sizes or device dimensions. For rapid prototyping the grid system is optional. In this case, the used components are aligned among each other. The different components are vertically arranged without the use of the grid system and will accrue in single rows with full-width columns at runtime.

# Content

Content announcement is one of the core tasks of a user interface. For this reason the GUI model provides multiple components to display different types of data. Thanks to the automatically immediate data-binding, a displayed value of a variable is always up to date. The headline component, is one of the components to display content. At modeling time, the size and the content of the headline can be specified. Like every other content in the properties view of a GUI model component, it can be determined as a composite of static content and expressions to display dynamic values of variables.

In addition to the headline, a text and a file component are provided as well. The file component is necessary to offer a download option for the user at runtime, since the access of a file variable using an expression displays only the file name. Besides this basic content announcement, GUI models offer specialized components to show e.g. images, thumbnails, alert boxes and progress bars. Thanks to the simplicity approach of DIME and the GUI model, the use of a special components is as simple as the data-binding of the text component.

# Tables

Tables can be used to display interrelated information (i.e. entries of list) in multiple columns. To bind a list variable to the table, a table load edge is provided. As a result of this, the source of the table is defined, so that the changes of the variable causes a refresh of the table without any additional effort. Besides the basic presentation of data, the table component offers features to sort and filter the displayed rows. To take advantage of this features, columns has to be specified for the table. The corresponding component, which is available in the palette of the GUI model, is the table entry component. Multiple properties can be set on a table entry, like the label and a sorting and filter option. If the options are enabled, the source variable for the column has to be specified by a table column load edge. This edge should be connected to a member of the expanded current variable of the source list. The filter and sort functions are implicitly defined based on the data type of the connected variable without any further effort. The actually displayed content of a table column, represented by a table entry, can be entirely customized by the use of all available components or just show the value of the binded variable. Similar to the remaining features of the GUI model, the developer just decides which features are needed and not how they are realized.

The table component can be used to select on entry of the source list variable. The choice property of the table can be set to enable a single or multiple selection. If a table row is selected at runtime, the value is written to a target variable, specified by a table target edge. Besides this functional aspects of the table, there are multiple other properties to personalize the rendering of the table like the bordering of the entries and a pagination.

# Forms

Forms encapsulates components which enable the user to modify the values of variables. In the GUI model only two different types of modifications has to be differentiated. On the one hand the form field component, which allows the editing of all primitive variables and on the other hand the form selection components like radio, combo box and check box for assignment tasks. As a common feature for all form components, a target variable has to be specified which will be modified at runtime, when the user makes changes. The connection between a form component and the target variable can either be done by a form submit edge for unidirectional editing and form load submit edge for bidirectional editing. The bidirectional editing results in the propagation, of the modified value of the variable to the form components when it is changed in another component as well.

The selection components can be used to realize an assignment of a selection, based on a source list variable, to a target variable. Depending on the desired kind of selection the corresponding component can be chosen. The selection components differ in the their multiplicity. This means that e.g. the radio component offers only one entry to be selected, whereas the check box allows multiple entries to be selected. The combo box component can be adjusted to accept multiple or just one selection in their properties. Independent of the concrete multiplicity, every selection component requires a source list variable and a target variable. The source variable can be connected to the component by a choice load edge, so that the current variable is available to be displayed in the inner scope. When an entry is chosen by the user, the target variable is assigned to the entry's value. The multiplicity of the target variable depends on the multiplicity of the selection component.

To edit primitive variables in GUI models, the form field component is provided. Similar to the selection components, a target variable connection is required. Every primitive data type like text, real or file is supported and furthermore special input types can be specified in the properties of the component. This offers the possibilities of additional semantics at modeling time, since the expected input can be defined as e.g. a color, a phone number or an URL. The generated input field will autonomously validate and parse the inserted values and offers special input assistance to the user at runtime, without any additional effort.

Every form component offers additional optional properties. A form field can be supplemented by a label and a help text, to clarify the intentions and multiple visual settings like sizes or colors. Another important aspect, when taking user input, is validation. Since the primitive form field components specify input types, a simple validation can be performed. In addition to this, the GUI model provides other restrictions to be imposed, like a minimal and maximal amount of inserted characters and a required flag property, which ensures that the form component is filled out. For highly specialized validations, a regular expression can be defined to fit particular requirements. The validation is performed at runtime. The color of the input field will change, to notify the validation status. In addition, an error text property can be given on the form component, which is shown if an invalid input is present.

The form components of the GUI model are based on the simplicity policy of DIME and facilitate the rapid design of user input processing. Even the complex task of validating the inserted data to guarantee the correct further use is simplified by predefined validations.

# Build-In Structural Components

Besides the different components placed in the template to display and modify the values of variables in the data context, structural components can be used to dynamically adapt the template to variables. The GUI model provides the basic structural components if and for represented by certain edges.

# IF Edge

The if edge can be used to display or hide a component and all of their inner components at runtime. To define a conditional indication, the if edge can be dragged from a variable to an arbitrarily component. An inverted condition can be created by negating the if edge in the properties. Based on a boolean evaluation of the variable, the connected component is shown or hidden when the result is falsely. Similar to the data-binding edges or expressions, the condition of the if edge is re-evaluated automatically, iff the corresponding variable is modified. The condition is implicit defined based on the type of the variable. Numeric primitive variables are considered as truly, if the value is higher than 0. Textual and list variables are evaluated truly when they are not empty. When a complex variables is evaluated, the result depends on a null check. This implicit conditions simplify the ease of use according to the principles of DIME.

# FOR Edge

Dynamic data structures like lists cannot be displayed in a static manner. To access every item of a list variable, the iterative for edge structural components is provided. The connection of a list variable to a component in the template using a for edge, results in the repetition of the target component for each element in the list at runtime. The current iteration variable, which can be expanded form the list variable, is available in the scope of the target and all inner component. In addition to this, an index variable can be declared on the properties of the for edge, which is also available in the iteration scope. A specialty is present when the connected variable is s primitive list. In this case no iterator variable can be expanded. Instead of that the name of the iterator variable has to be specified on the edge properties, to access the value of the iterator.

The structural components enable the developer to define dynamic behavior and responsiveness, by just dragging edges between the variables and components. The usage is prepared intuitively to abbreviate the way to meet the target solution.

# Data-Type Dependent

# Process-Model Dependent

# GUI-Model Dependent

# Processes

# Short-running process

  • contain other short-running sub-processes and arbitrary SIBs (except SaveToDB)
  • can contain long-running processes which are spawned and non-blocking
  • only process type that may have java native types as data

# Basic Process

  • as described above, no further restrictions

# Interactable Process

  • may have java native types as data, but not in signature
  • are generated as REST services
  • is the only process type that can be used in interaction processes

# Security Process

  • interface:
    • "User subject" input
    • arbitrary other data input
    • two branches, "granted" and "denied"
  • may contain arbitrary SIBs and all short-running processes
  • must not contain interaction processes, long-running processes, GUI components
  • can be used in long-running process as guard (within a GuardContainer attached to an InteractionSIB)
  • (maybe later: can be attached to LRPs in DAD as guard for launching them)

# Interaction Process

  • Contains only interactable processes, GUI components and SaveToDB
  • DataContext may only contain dime types (as defined in .data model) and primitive types
  • Can be used as sub-component in GUI components
  • Can be used in long-running processes
  • A single interaction process is defined in DAD as "application entry point" which is executed directly after login

# Long-running process

# GUI Component

  • data context can only contain dime types and primitive types
  • special components: ** TODO List: shows all long-running processes waiting for a user interaction that can be performed by the logged-in user ** LRP Launcher: shows a list of long-running process types that can be started by the logged-in user ** Interaction Component: a Cinco libComp to an interaction process serving as a sub-component with an own routing
  • can be used as SIBs in interaction processes (nowhere else) ** every button/link defines a branch in that process ** every EndSIB of every interaction process that is used as an interaction component (i.e. sub-component) defines a branch in that process

# Search Query Models

  • can be used in long-running and short-running processes
  • must not be used in interaction processes
Last Updated: 3/8/2021, 2:03:34 PM