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Ilkka Seppälä 2020-08-29 16:42:46 +03:00
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@ -9,13 +9,16 @@ tags:
--- ---
## Intent ## Intent
Pass data with multiple attributes in one shot from client to server, to avoid multiple calls to remote server.
Pass data with multiple attributes in one shot from client to server, to avoid multiple calls to
remote server.
## Explanation ## Explanation
Real world example Real world example
> We need to fetch information about customers from remote database. Instead of querying the attributes one at a time, we use DTOs to transfer all the relevant attributes in a single shot. > We need to fetch information about customers from remote database. Instead of querying the
> attributes one at a time, we use DTOs to transfer all the relevant attributes in a single shot.
In plain words In plain words
@ -23,16 +26,17 @@ In plain words
Wikipedia says Wikipedia says
> In the field of programming a data transfer object (DTO) is an object that carries data between processes. The > In the field of programming a data transfer object (DTO) is an object that carries data between
motivation for its use is that communication between processes is usually done resorting to remote interfaces > processes. The motivation for its use is that communication between processes is usually done
(e.g., web services), where each call is an expensive operation. Because the majority of the cost of each call is > resorting to remote interfaces (e.g. web services), where each call is an expensive operation.
related to the round-trip time between the client and the server, one way of reducing the number of calls is to use an > Because the majority of the cost of each call is related to the round-trip time between the client
object (the DTO) that aggregates the data that would have been transferred by the several calls, but that is served by > and the server, one way of reducing the number of calls is to use an object (the DTO) that
one call only. > aggregates the data that would have been transferred by the several calls, but that is served by
> one call only.
**Programmatic Example** **Programmatic Example**
Let's first introduce our simple customer DTO class. Let's first introduce our simple `CustomerDTO` class.
```java ```java
public class CustomerDto { public class CustomerDto {
@ -60,7 +64,7 @@ public class CustomerDto {
} }
``` ```
Customer resource class acts as the server for customer information. `CustomerResource` class acts as the server for customer information.
```java ```java
public class CustomerResource { public class CustomerResource {
@ -94,10 +98,12 @@ Now fetching customer information is easy since we have the DTOs.
``` ```
## Class diagram ## Class diagram
![alt text](./etc/data-transfer-object.urm.png "data-transfer-object") ![alt text](./etc/data-transfer-object.urm.png "data-transfer-object")
## Applicability ## Applicability
Use the Data Transfer Object pattern when
Use the Data Transfer Object pattern when:
* The client is asking for multiple information. And the information is related. * The client is asking for multiple information. And the information is related.
* When you want to boost the performance to get resources. * When you want to boost the performance to get resources.