DCI - Distributed Computing Infrastructure

Characteristics of application
Applications are:
 - Workflow solutions
 - Enterprise solutions
 - Customer Relationship solution

Customers => Sever => Database

Traditional Client / Server Environment(linked by a network using protocol such as Microsoft Network)
Strength(Application run on Local Area Environment)
 - high network speed as compared to over the Internet
 - easy of ensuring security
 - consistent UI using Windows
 - well controlled/consistent client platform
 - good control of starting and ending of application (session management)
Weakness
  - Specific client software required on each Individual terminal(difficult in implementation and maintenance)

Web-based Client / Server Environment(linked by a network using Internet protocol - TCP/IP)
Strength
 - application running on standard Intranet/Internet protocol(TCP/IP)
 - easy implementation and maintenance
 - consistent UI on different platforms(browser UI)
Weakness
 - lower network speed as compared to LAN
 - difficult to ensure security(over public switching telephone network)

Internet Protocol
TCP: Transmission Control Protocol
IP: Internet Protocol
HTTP: HyperText Transport Protocol
HTTPS: HyperText Transport Protocol Secure
Cookie Format(Write onto client machine):
Set-Cookie: NAME=VALUE; expired=DATE; path=PATH; domain=DOMAIN_NAME; secure
 - expires syntax must be "Weekday, dd-mmm-yyyy hh:mm:ss GMT"
 - domain must have at least 2 dots(3 dots for domains outside USA)
 - path refers to a URL path within the Web server
 - secure, if present, limits transmission to secure server

Internet 
Plug-ins: are programs modules loaded by the browser to handle specific file-formats.
Internet application and Intranet application

Empowering the Client
Scripting (no compilation needed)
          JavaScript (Netscape) - supported by almost every browsers, such as IE, Netscape, etc
          VBScript (Microsystem)
Components (compilation needed) - IE
          Java Applet (Sun Microsystem)
          ActiveX Control (Microsoft)

Using LINQ or Lambda Expressions to Entities - Entity Framework Query Options

LINQ to Entities
a. Create new entityframework(EF) called DefestyEntity;
b. Tables generated by EF are Customers, Orders, and so on;
c. Queries must be well defined at compile time;

Codes:
DafestyEntity ctx = new DafestyEntity();

var query = from x in ctx.Orders
                    where x.Customer.CustomerID == "Tom"
                    select x;
foreach (var x in query)
    Console.WriteLine("{0} {1}", x.OrderID, x.OrderDate);

LINQ Key Words
- from
  Specifies a data source and a range variable (similar to an iteration variable).
- where
  Filters source elements based on one or more Boolean expressions separated by logical AND and OR operators(&& or ||)
- select
  Specifies the type and shape that the elements in the returned sequence will have when the query is executed.
- group
  Groups query results according to a specified key value.
- into
  Provides an identifier that can serve as a reference to the results of a join, group or select clause.
- order by
  Sorts query results in ascending or descending order based on the default comparer for the element type.
- join
  Joins two data sources based on an equality comparison between two specified matching criteria.


Lambda Expressions
a. A lambda expression is an anonymous function that can contain expressions and statements, and can be used to create delegates or expression tree types.

Codes:
ctx.Orders.Where(x => x.CustomerID =="Tom");