Examen 2 P2 Flashcards
Message passing between a pair of processes can be supported by two message communication
operations:
Send and receive operations
In this form of communication, the use of the send operation is non-blocking, the receive operation can
have blocking and non-blocking variants
the asynchronous communication
We can describe this as the guaranteed to be deliver the message despite a reasonable number of
packets being dropped or lost.
Reliability
Both forms of communication (UDP and TCP) use _________, which provides an endpoint for
communication between processes
the socket abstraction
In this form of communication, the sending and receiving processes synchronize at every message. In
this case, both send and receive are blocking operations.
the synchronous communication
Any process may make use of multiple of this elements to receive messages, but a process cannot share
them with other processes on the same computer
Ports
The internet protocols, and the local port pairs define the:
Message destination
This consist of transmitting a message between a socket in one process and a socket in another process.
Interprocess communication
is sent by UDP is transmitted from a sending process to a receive process without acknowledgement or
retries.
A datagram
Messages may be dropped occasionally, either because of a checksum error or because no buffer space
is available at the source or destination is’s called:
Omission failure
This defines reliable communication in terms of two properties: integrity and validity.
Failure model
This was oeiginated from BSD 4.x UNIX, provides the abstraction of a stream of bytes to which data may
be written and from which data may be read.
The API to the TCP protocol
This assume that when a pair of processes are establishing a connection, one of them plays the client
role and another plays the server role, but thereafter they could be peers.
The API for stream communication
The TCP protocol attempts to match the speeds of the processes that read from and write to a stream,
this is called:
Flow control
These items transmitted in messages can be data values of many different types, and not all computers
store primitive values such as integers in the same order.
The individual primitive data
The TCP protocol uses an acknowledgement scheme. If the sender does not receive an
acknowledgement with a time out, it retransmits the message and this is performed when:
There is lost messages
This is the process of taking a collection of data items and assembling or disassembling (respectively)
into a form suitable for transmission in a message.
Marshalling and Unmarshalling
They are three alternative approaches to external data representation.
XML, CORBAS’s, Java’s object serialization
The first was designed for defining the appearance of web pages. the second one was designed for
writing structured documents for the Web
HTML and XML
They are tagged with ‘markup’ strings. The tags are used to describe the logical structure of the data and
to associate attribute-value pairs with logical structures.
XML data items
XML is ________ in the sense that users can define their own tags, in contrast to HTML, which uses a
fixed set of tags
Extensible
This is a markup language that was defined by the World Wide Web Consortium (W3C) for general use
on the Web.
XML
The structure of an XML document is defined by pairs of these elements enclosed in angle brackets.
Tags
They define the name of values associate to tags in XML schemes.
XML Attributes
This is used to enable clients to communicate with web services and for defining the interfaces and
other properties of web services.
XML - service
All of the information in XML elements must be expressed as character data.
But the question is: how do we represent encrypted elements or secure hashes?
Binary data
Every start tag has a matching end tag and all tags are correctly nested these are?
Basic rules of XML
Every XML document must have this as its first line and must at least specify the version of XML in use
(Which is currently 1.0)
A prolog
This is a set of names for a collection of element types and attributes that is referenced by a URL.
XML namespace
This defines the elements and attributes that can appear in a document, how the elements are nested
and the order and number of elements, and whether an element is empty or can include text.
XML schema
This protocol is based on a trio of communication primitives: doOperation, getRequest and sendReplay.
The request-replay protocol
This scheme involves the management of messages requires that each message have a unique message
identifier by which it may be referenced.
Message Identifiers
As its name indicates, it is a mechanism to call a procedure or a function available on a remote
computer.
Remote Procedure Call (RPC)
This uses the HTTP protocol to pass information from a client computer to a server computer and uses a
small XML vocabulary to describe the nature of requests and responses.
XML- RPC parameters
This specifies a procedure name and parameters in the XML request, and the server returns either a
fault or a response in the XML response
XML – RPC client
Data model , request structures and response structures are parts of
XML - RPC
They are a simple list of types and content - structs and arrays are the most complex types available
XML - RPC structure
