scea,summarise

a architecture should have 7 features.
perfermance:to measure a system's perfermance,you can  use how many seconds a page form respose or how many transactions can be dealed in one seconds.
reliablity:  ensure the intergrity and persistency of all transactions in one application,also make sure the perfermance when load increased.
availablity:ensure the server/resource can always be accessed. even if some component fail,you can user redundent hardware or software to archieve it.
scalablity: when the system's process increase , can use vertical or horizontal to improve it. ventical scalable  adds hardware to the machine , as memory,processor,or disks .horizontal scalable add servers to the system .
extensibility:to add new fonctionality or modify exist functionality  of a system.you should finish this with out impacting exist functionality ,you can use low coupling,interface,encapsulation to archieve .
managebility: easy to change the system configration with out impacting the system ,
maintainablity: easy to correct flaws in component with out impacting other components.you can use low coupling,modularity and documents to archieve this.
security: protect the system to be compromise, to make sure the data confidentiality and  integrity ,also relate to  denial -of-service attacks.