Transitioning from Server to Client Side Web Development with Angular 2

Part 1:History

1993 : Someone somewhere uses C to customize the HTML devlivered to a brower.Yahoo is born .Perl,ColdFusion,PHP(all via CGL) follow.
1996 : Iframes allow partial page to be loaded via parameterized URL.
1998 : HTML4/DHTML - JS manipulating DOM and dynamic style
2002 : XHR/Ajax opens door from “single page apps”.
2006 : JS & CSS frameworks emerge,large apps become hard to maintain.
2010 : MVC(ExtJS,Angular) addresses separation of concerns.Unit testing and TDD emerges and grows.
2013 : Asm/WebAsm-based languages address JS shortcomings.
2015 : First frameworks written in type safe languages

Web finally “Just another native environment”.
Server does not differentiate by client - Same REST everywhere,server not responsible for view.
Web developers avoid politics of fragile server builds,work with tooling and workflows tuned to their productivity instead of some other team’s
Faster,more reliable web development due to build process and type safety.

—————- Thin vs. Fat Client ——————–

A thin client wholly relies on the server for client view management.
A server session forms the context by which views progress
Consider a six-page wizard:each view sequenced and sent by server.
Network transaction boundary on every view change.
Scaling is difficult with server-based sessions since a cluster node reboot drops the session and in-flight user work.Requires session replication,rerouting requests on the fly,etc.
Fat(Standalone) client is one which only communicates changes to model.
In out wizard example,user has expectation of losing data if their device reboots.Data that is submitted at end of wizard is data from every page.
Network transaction boundary is on reads or writes to model.
REST models CRUD via POST,PUT,GET,DELETE.Simple
Scaling is simple,any server endpoint can accept transactional requests without reference to previous transactions.

Transactional systems are always based on the credentials of a requesting principal.One can’t unlock or start a vehicle without a key.The key is the credentials
Computers systems are not different.A credential identifies a transactional counterparty.
For a human,a credential might be a username and password.For inter-computer communication,we might use a public/private key pair.
In any case,we have to decide who is presenting a command before deciding what they can do.

In the example of a vehicle,the key generally grants complete operational access to the vehicle.Some vehicles have “valet keys” with downgraded access
Such access levels delineate authorizations or permissions.
Now scale permissions to the level of 100k people in a large organization.Example:All members may be granted office access,but each to certain campuses.Only a few members may have access ti payroll,etc.There can easily be hundreds of thousands of permissions once CRUD aspects of each one are captured.