A Real Estate Inc. (AREI) sells houses. People who want to sell their houses sign an online agreement with AREI and provide information on their houses through AREI’s website. This information is kept in a database by AREI and a subset of this information is sent to the citywide multiple listing service used by all real estate agents. AREI works with two types of potential buyers (who may have seen the houses from other websites and then contact AREI). Some buyers have an interest in one specific house. In this case, AREI’s agents are able to print information about this house from its database, which they use to help show the house to the buyer. Other buyers seek AREI’s advice on finding a house that meets their needs. In this case, the buyer completes an online buyer information form on AREI’s website, and AREI real estate agents can search AREI’s database to find if there are listed houses that meet their needs. The results of these searches can be printed and used to help the real estate agent show houses to the buyer.

Required:
a. Choose one of the classes and create a set of invariants for attributes and relationships and add them to the CRC card for the class.
b. Choose one of the methods in the class that you chose and create a contract and a method specification for it. Use OCL to specify any pre- or post condition and use both Structured English and an activity diagram to specify the algorithm.