The two services involved with the distribution of messages ...

[itsmyluck]

The two services involved with the distribution of messages within a DS are distribution and _________.
 
  What will be an ideal response?

Question 2

Explain the three types of visibility for package elements: public, private, and protected.
 
  What will be an ideal response?

[wergv]

Answer to Question 1

integration

Answer to Question 2

Visibility of an element inside a package decides what other packages can access that element. The elements owned by a package can be assigned a specific visibility:
 Public. Identified with a plus sign, public elements are visible to all other packages. In most modeling tools, elements are public by default.
 Private. A minus sign next to an element specifies that the element may be seen only by members of the same package.
 Protected. Like classes, packages can be generalized. For example, you may define a package called Search that contains a certain set of classes common to search activities within the system. You may then define other packages such as Patient Search or Medical Service Search that inherit the artifacts within the Search packages. These child packages can see both public and protected elements within Search, while other packages have access only to its public items.