As of now i am able to perform following operations in DNG using OSLC:

1. Get all requirements from DNG project.
2. Create folder in Root folder.
3. List of all the folders in DNG project.
4. Creating requirements and linking of other requirements with that.
5. Get requirements from a folder.
6. Get requirements from a collection

Here are other queries :
a) is it possible to create new Collection and add requirements in that using OSLC. but at the time of creating collection i need to check if there is already a collection with same Name then i need to retrieve that collection instead of creating new.

b) Same as collection i need to check if there is already a requirements with the same name then i need to retrieve  that requirement and allow user to make changes in the requirements linked with that(Add or remove more requirements). and then Update the same requirement in DNG. I am able to retrieve requirement (of couse not by name but all in folder/project). how can i  get (satisfiedBy) links associated. After adding/requirement, how can i updated requirement back to that DNG.

I am using OSLC, Java. Thanking in Advance.