CUSTOMER_CODE
SMUDE
DIVISION_CODE
SMUDE
EVENT_CODE
SMUJAN15
ASSESSMENT_CODE MIT3032_SMUJAN15
QUESTION_TYPE
DESCRIPTIVE_QUESTION
QUESTION_ID
16431
QUESTION_TEXT
Explain Parameter passing semantics.
Parameter passing semantics:
Call by value: all parameters are copied into a message that is
transmitted. It does not pose problem for simple data types such as
integers, small arrays and so on. Passing large data types like multi
dimensional arrays, trees etc. can consume much time for transmission
of data that may not be used.
Class by reference: this is possible only in a distributed shared memory
system, it is also possible in object oriented systems, because in this
case client needs to pass the name of the objects, which are like
references. In object oriented systems it is called call-by-object
reference. (for details refer page 61)
SCHEME OF
EVALUATION
Possibly or may be Call semantics: the weakest semantics. Not really
appropriate for RPC. Caller waits until a predetermined amount of
time and then continues with the execution. Suitable in an environment
that has high probability of successful transmission of messages.
Last-One call semantics: the calling of remote procedure by the caller,
execution of procedure by callee, and return of the result to the caller
will eventually be repeated until the result of the procedure execution
is received by the caller. i.e., the results of the last executed call are
used by the caller.
Last – of – Many Call semantics: similar to last-one semantics, except
orphan calls are neglected.
• Call identifiers are used to uniquely identify each call
• When a call is repeated , it is assigned a new identifier
• Each response message has the corresponding call identifier
• A caller accepts a response only if the call identifier matches with
that of the most recently repeated call.
Each point carry 2 marks
QUESTION_TYPE
DESCRIPTIVE_QUESTION
QUESTION_ID
16436
QUESTION_TEXT
Explain
i.Characteristics of human oriented names
ii.Human oriented hierarchical naming schemes
iii.Issues in context binding
iv.Issues involved in using a single global name space
i.Characteristics of human oriented names: (2.5 marks)
a.Character strings that are meaningful to the users
b. They are defined by the users
c. Different users can define their own suitable names for a shared
object
d. They are variable in length and different names could be used
for the same object
e. Same name can be used by different users to refer different
objects
ii.Human oriented hierarchical naming schemes (2.5 marks)
a. Combining an object’s local name with its host name
b. Interlinking isolated name spaces into a single name space
iii.Issues in context binding (2.5 marks)
a. When the name server is presented with the name to be
resolved.
b. The server looks at the authoritative name servers for the
named object
c. If the authority attribute does not contain he name server
corresponding to the given name
iv.Issues involved in using a single global name space (2.5 marks)
a. Partitioning name space into contexts
b. The notion of context is used for partitioning name space into
smaller components
c. Partitioning into contexts is done by using clustering conditions
SCHEME OF
EVALUATION
QUESTION_T
DESCRIPTIVE_QUESTION
YPE
QUESTION_I
72436
D
QUESTION_T
Explain three basic naming related access control.
EXT
Object Names as Protection Keys
In this method, an object’s name acts as protection key for the object. A
user who knows the name of an object (i.e. has the key for the object) can
access the object by using its name.
SCHEME OF
EVALUATIO
N

The scheme does not guarantee a reliable access control
mechanism.

It does not provide the flexibility of specifying the modes of access
control.
Capabilities
This is a simple extension of the above scheme that overcome its
limitations. As shown below, a capability is a special type of object
identifier that contains additional information redundancy for
protection.
Figure 9.1: The two basic parts of a capability
It may be considered as an unforgettable ticket that allows its
holders to access the object (identified by its object identifier) in
one or more permission modes (specified by its access control
information part).
iii) Associating Protection with Name Resolution Path
Protection can be associated with an object or with the name
resolution path of the name used to identify the object. The more
common scheme provides protection on the name resolution path.
QUESTION_TYPE
DESCRIPTIVE_QUESTION
QUESTION_ID
122289
QUESTION_TEXT
Define Load-Balancing algorithms. List & explain the various
categories of load balancing algorithms
Definition of load balancing algorithm (2 marks)
Categories of load balancing algorithm:
SCHEME OF
EVALUATION
*
Static
*
Dynamic
*
Deterministic
*
Probabilistic
*
Centralized
*
Co-operative
*
Non - cooperative
(1 marks * 8=8 marks)
QUESTION_TYPE
DESCRIPTIVE_QUESTION
QUESTION_ID
122290
QUESTION_TEXT
Explain the alternative semantic models that are better suited for a
distributed implementation
Explanation must includes: (4 marks)
SCHEME OF
EVALUATION
*
Session semantics
*
Immutable files (4 marks)
*
Atomic transactions (2 marks)
QUESTION_TYPE
DESCRIPTIVE_QUESTION
QUESTION_ID
122292
QUESTION_TEXT
Describe various features of a Good Naming System
i.
Location Transparency (2 Marks)
ii.
Location Independency (2 Marks)
SCHEME OF EVALUATION iii.
Scalability (2 Marks)
iv.
Uniform naming convention (2 Marks)
v.
Multiple (2 Marks)