1
00:00:02,150 --> 00:00:09,020
The proxy battle is our last structural design pattern proxies are usually entities that represent other

2
00:00:09,020 --> 00:00:12,560
entities and the proxy design pattern does just that.

3
00:00:12,920 --> 00:00:15,240
It acts as another object.

4
00:00:15,650 --> 00:00:20,950
It is basically a class that serves as an interface between a client application and another object.

5
00:00:22,570 --> 00:00:25,120
The typical usages for the proxy button are.

6
00:00:26,350 --> 00:00:32,800
When we need to create a rapport to cover the main object's complexity from the client or when we need

7
00:00:32,800 --> 00:00:38,350
to ensure the security of a given resource and we need a proxy to check if the client is allowed to

8
00:00:38,350 --> 00:00:41,410
access a resource that the proxy is representing.

9
00:00:43,070 --> 00:00:45,870
This is a typical UML diagram to the proxy battle.

10
00:00:47,400 --> 00:00:52,740
In our code, we would have a server which serves one file to the client application.

11
00:00:53,760 --> 00:01:00,540
However, the client will call the server directly, but it will ask the proxy for the file, the proxy

12
00:01:00,540 --> 00:01:06,290
will ensure that the client is entitled to receive the file, and if yes, then it will access the original

13
00:01:06,300 --> 00:01:10,160
resource on the client's behalf and will serve the file to the client.

14
00:01:11,610 --> 00:01:13,740
The witnesses for this pattern are.

15
00:01:15,290 --> 00:01:21,020
We can have only one proxy, therefore, if you want to do error handling, security handling or one

16
00:01:21,020 --> 00:01:26,960
to manage other aspects of dealing with the original resource, then you will have to do it in a single

17
00:01:26,960 --> 00:01:27,410
class.

18
00:01:28,790 --> 00:01:33,580
Also, it provides another layer of abstraction which can increase the complexity of the program.

19
00:01:34,890 --> 00:01:37,860
Let's have a look at the implementation of this pattern in the code.