Business Components as Rest web services in GeneXus

To expose a Business Component (henceforth the BC) as a Rest web service, you only need to do the following configuration at the BC properties:

• Expose as web service = TRUE
• Web Service Protocol = REST Protocol

After generating the BC, it's exposed as a Rest service and it can be consumed using the HTTP protocol (in particular, the HttpClient data type) in GeneXus.

Note that the specification document of this service can be generated automatically. See Documenting RestFul services.

Methods to call a Business Component exposed as Rest service

The different CRUD operations of the BC are accessed using different HTTP methods.

• Create: using HTTP POST method.
• Read: using the HTTP GET method.
• Update: using the HTTP PUT method.
• Delete: via the HTTP DELETE method.

Endpoint URI for the Bussiness Component

The endpoint URI for Business components is

 <server uri>/rest/<bc name>

E.g: If "Product" is a BC exposed as Rest, the URI of the service would be: 172.19.12.1/MyApp/rest/Product

If the BC belongs to a module, the endpoint URI is

<server uri>/rest/<module>/<bc name>

For example, if the module is "module2" under "module1", the URI would be: <server uri>/rest/module2/module1/<bc name>.

How to pass the parameters for calling a Rest BC

The parameters have to be separated by commas in the URI.

Depending on the CRUD operations involved, there are some aspects to consider.

Create

URI: <server uri>/rest/<module>/<bc name>/<param1>,<param2>,..,<paramN>.

The parameters have to be sent in the body of the HTTP request. However, the Primary Key has to be sent in the URL.

The format of the URL is the same as in the GET method. The PK values have to be separated by commas.

<server uri>/rest/<module>/<bc name>/<param1>,<param2>,..,<paramN>

Example:

Method: POST 

URI: http://server/baseURL/rest/City/2

Body:
{
"CityName": "Rio de Janeiro",
"CityId": "2"
}

Return: Http code 201 

Body:
{
"CityName": "Rio de Janeiro",
"CityId": "2",
"gx_md5_hash": "24258169b5151be175ed72c92fd2c561"
}

HowTo: Inserting data using a BC exposed as Rest service 

Read

URI: <server uri>/rest/<module>/<bc name>/<param1>,<param2>,..,<paramN>.

The PK values have to be separated by commas.

Example

Method: GET 

URI http://server/baseURL/rest/City/1

Return: Http code 200

{
"CityName": "Montevideo"
"CityId": "1"
"gx_md5_hash": "24258169b5151be175ed72c92fd2c561"
}

The body contains a hash value, needed for executing an UPDATE.

HowTo: Retrieving data from a BC exposed as a Rest service

Update

First get the data by its PK, using the HTTP GET verb and this generic URI:

<server uri>/rest/<module>/<bc name>/<param1>,<param2>,..,<paramN>.

Then update the data using the HTTP PUT verb. Similar to the POST, the PK parameters are included in the query string. The others in the body.

Example

Method: PUT 

After reading the gx_md5_hash using GET method : 

URI http://server/baseURL/rest/City/1

Body:

{
"CityName": "Roma",
"CityId": "1",
"gx_md5_hash": "24258169b5151be175ed72c92fd2c561"
}

Return: Http code 200

HowTo: Updating data using a BC exposed as a Rest service

Delete

URI: <server uri>/rest/<module>/<bc name>/<param1>,<param2>,..,<paramN>.

Example

Method DELETE

URI : http://server/baseURL/rest/City/2

HowTo: Deleting data from a BC exposed as a Rest service