Sub-task mechanism for development of task-based user interfaces

1. A computerized method comprising:

providing a plurality of user interfaces (UIs) pertaining to a business task, wherein

the business task comprises

a subtask,

the subtask comprises

at least one subtask step,

the subtask is defined within the business task, and

the subtask is configured to reuse a portion of another business task; and

allowing navigation through the plurality of UIs, wherein

the navigation comprises bi-directional navigation, and

the bi-directional navigation is facilitated by

maintaining one or more local variables of a first invocation of the subtask, wherein

the one or more local variables are maintained after the first invocation is completed,

storing navigation history data in a navigation stack, wherein

the navigation history data comprises

 an identifier of each of the at least one business subtask step traversed during the navigation, and

 an identifier of a local context associated with the each of the at least one business subtask step traversed during the navigation, and

defining a context chain by storing a parent context identifier of a parent of the subtask in a local context of the subtask, wherein

the context chain is configured to be used as a logical call stack.

2. The method of claim 1 , wherein the subtask further comprises:

a predefined reusable module.

3. The method of claim 1 , wherein

the subtask is defined within the business task by in a design environment, and

the design environment is configured to allow a definition of the subtask within the business task without programming code being written.

4. The method of claim 3 , wherein providing the plurality of UIs pertaining to the business task comprises:

identifying a collection of metadata created for the business task using

a visual representation of the business task, and

properties associated with corresponding steps within the business task, wherein

the design environment is further configured to allow specification of

the visual representation, and

the properties; and

processing the collection of metadata to provide the plurality of UIs pertaining to the business task.

5. The method of claim 1 , wherein the subtask is defined within the business task, and

a process of the subtask being defined is transparent to a user performing the navigation.

6. The method of claim 5 , wherein bi-directional navigation is further facilitated by

receiving a previous operation request;

determining that a local context identifier from a top step frame in a backward navigation stack is the same as a current local context identifier; and

adding a current step frame to a forward navigation stack.

7. The method of claim 6 , wherein the bi-directional navigation is further facilitated by

determining that the local context identifier from the top step frame in the backward navigation stack is not the same as the current local context identifier;

switching the local context; and

adding the current step frame to the forward navigation stack.

8. The method of claim 1 , wherein the bi-directional navigation is further facilitated by

invoking the subtask.

9. The method of claim 1 , wherein the bi-directional navigation is further facilitated by

accessing the one or more local variables pertaining to the first invocation of the subtask during a second invocation of the subtask.

10. The method of claim 1 , wherein the bi-directional navigation is further facilitated by

re-entering or exiting the subtask through any one of a previous operation or a next operation.

11. The method of claim 10 , wherein the re-entering or exiting the subtask comprises:

storing an execution path of the business task;

determining whether the execution path has changed; and

determining, based on an execution plan change, whether

local variables pertaining to a previous subtask invocation are to be utilized, or

new local variables are to be created.

12. The method of claim 11 , wherein

storing the execution path comprises

storing a first portion of the navigation history in a forward navigation history stack, and

storing a second portion of the navigation history in a backward navigation stack; and

determining whether the execution path has changed comprises

comparing a next step to be executed with a top step frame on the forward navigation history stack.

13. The method of claim 11 , wherein the re-entering or exiting the subtask further comprises:

creating a local context for the subtask step;

adding an identifier of the subtask and an identifier of the local context associated with the subtask step to the navigation stack; and

switching to the local context associated with the subtask step.

14. A machine-readable storage medium having executable instructions to cause a machine to perform a method comprising:

providing a plurality of user interfaces (UIs) pertaining to a business task, wherein

the business task comprises

a subtask,

the subtask comprises

at least one subtask step,

the subtask step is defined within the business task and

the subtask is configured to reuse a portion of another business task; and

allowing navigation through the plurality of UIs, wherein

the navigation comprises bi-directional navigation, and

the bi-directional navigation is facilitated by

maintaining one or more local variables of a first invocation of the subtask, wherein

the one or more local variables are maintained after the first invocation is completed,

storing navigation history data in a navigation stack, wherein

the navigation history data comprises

 an identifier of each of the at least one business subtask step traversed during the navigation, and

 an identifier of a local context associated with the each of the at least one business subtask step traversed during the navigation, and

defining a context chain by storing a parent context identifier of a parent of the subtask in a local context of the subtask, wherein

the context chain is configured to be used as a logical call stack.

15. The machine-readable storage medium of claim 14 , wherein

the subtask is defined within the business task, and

a process of the subtask being defined is transparent to a user performing the navigation.

16. The machine-readable storage medium of claim 15 , wherein the bi-directional navigation is further facilitated by

invoking the subtask; and

accessing the one or more local variables pertaining to the first invocation of the subtask during a second invocation of the subtask.

17. A system comprising:

at least one processor; and

a runtime engine configured to be executed by the at least one processor to

provide a plurality of user interfaces (UIs) pertaining to a business task, wherein

the business task comprises

a subtask,

the subtask comprises

at least one subtask step,

the subtask is defined within the business task, and

the subtask is configured to reuse a portion of another business task, and

allow navigation through the plurality of UIs, wherein

the navigation comprises bi-directional navigation,

the runtime engine is configured to facilitate the bi-directional navigation by virtue of being configured to

maintain one or more local variables of a first invocation of the subtask, wherein

 the one or more local variables are maintained after the first invocation is completed, and

the runtime engine comprises

a navigation stack, wherein

 the navigation stack is configured to store navigation history data, and

 the navigation history data comprises

 an identifier of each of the at least one business subtask step traversed during the navigation, and

 an identifier of a local context associated with the each of the at least one business subtask step traversed during the navigation, and

a context chain, wherein

 the context chain is configured to be used as a logical call stack by virtue of being configured to store a parent context identifier of a parent of the subtask in a local context of the subtask .

18. The system of claim 17 , wherein

a process of the subtask being defined is transparent to the a user performing the navigation.

19. The system of claim 17 , wherein

the context chain is formed from a chain of local contexts created for each

subtask invocation, and

each local context in the context chain is configured to store a parent

context identifier of a parent of the each subtask.