Advanced Business Systems (ABS) is a consulting and staffing company providing specialized staffing and consulting services to clients in a variety of different industries. It has offices in major U.S. metro areas and has ongoing relationships with Fortune 500 companies. Its areas of services range from software development and network engineering to geo-information systems. It has fifty (50) plus regional offices in U.S. and five (5) offices in Canada. It plans to expand to other countries in the future.When an ABS client company determines that it will need a contractor or temporary professional, it issues a staffing request against the contract it had previously negotiated with ABS. The contract manager in ABS reviews the staff request and ensures that the request is valid with its current contract with its client from the database.If the request is not valid, the contract manager sends the staffing request back to the client and explains the reasons and asks for the need for starting a new contract.If the request is valid, the contract manager will start recruiting requests by putting the request into its staffing database. The staffing request is then sent to ABS placement department.In the placement department, the placement specialists will check the job requirements and candidates qualifications.If there is a qualified candidate, the specialist will notify the candidate and put a note in the database.If a qualified candidate cannot be found or not immediately available, the specialist notifies contract managers and recruiting department; the recruiting department starts search outside immediately.The recruiting department normally has thirty (30) days to find an outside candidate and send the qualified candidates to the placement department to review. If an internal qualified candidate is confirmed with his / her availability, the confirmation will be sent to the arrangement department. In the arrangement department, the candidate works with the specialists to further confirm the placement details, such as starting date, location, compensation (e.g., per diem), and travel arrangement. The final confirmation will be sent to the client along with a billing schedule. If the client agrees with the arrangement, he/she acknowledges the arrangement with contract managers in the contract department. The contract manager then puts a memo into its database and closes the request.Note: You may create and / or assume all necessary assumptions needed for the completion of this assignment.Write a three to four (3-4) page paper in which you:Create a package diagram of the problem domain layer using the communication diagrams and the CRUDE matrix through the use of graphical tools in Microsoft Word or Visio, or an open source alternative such as Dia. Note: The graphically depicted solution is not included in the required page length.Perform and explain the verification and validation walk-through of the package diagram.Create a set of invariants for attributes and relationships and add them to the CRC cards for each class in the structural model using Object Constraint Language (OCL).List the classes in the structure model. Choose one (1) class and create a contract for each method in that class. Note: Be sure to use OCL to specify the preconditions and the post conditions.Create a method specification for each method using both structured English and activity diagram for the algorithm specification through the use of graphical tools in Microsoft Word or Visio, or an open source alternative such as Dia. Note: The graphically depicted solution is not included in the required page length.Use at least two (2) quality resources in this assignment. Note: Wikipedia and similar Websites do not qualify as quality resources.Your assignment must follow these formatting requirements:Be typed, double spaced, using Times New Roman font (size 12), with one-inch margins on all sides; citations and references must follow APA or school-specific format. Check with your professor for any additional instructions.Include a cover page containing the title of the assignment, the student’s name, the professor’s name, the course title, and the date. The cover page and the reference page are not included in the required assignment page length.Include charts or diagrams created in Visio or Dia. The completed diagrams / charts must be imported into the Word document before the paper is submitted.The specific course learning outcomes associated with this assignment are:Determine the steps and principles of design modeling with UML.Document and describe the different state of objects throughout the life cycle.Use technology and information resources to research issues in procuring and designing project requirements.Write clearly and concisely about project requirements and design topics using proper writing mechanics and technical style conventions.