Jester - the Jolie rEST routER
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README.md

README.md

Jester (Jolie 1.6.0 Beta or greater required)

Jester - the Jolie rEST routER (and related tools)

tools/jolie2rest (Jolie 1.6.0 Beta or greater required)

This tool allows for the creation of:

  • a declaration for the REST router in order to automatically publish an existing jolie microservice into the router
  • a Swagger interface which reports all the API published in the router

Usage: jolie jolie2rest.ol router_host [swagger_enable=true|false] [easy_interface=true|false] Ex:

jolie jolie2rest.ol localhost:8080 swagger_enable=true easy_interface=false

It is worth noting that the parameter router_host identifies the location where the router is listening for, it does not represent the location of the target service. The tool will get the lits of the service to be analyzed from the file

service_list.txt

Each line of the file service_list.txt represents a service to be analyzed, in particular the line syntax is: path of the ol file of the service , name of the input port to be analyzed EX:

./demo/demo.ol, DEMO

It is important to highlight that a microservice can have more than one inputPort with different operations declared in it. If more inputPorts must be analyzed, then a line for each of them must be reported into the file service_list.txt.

REST annotations on the jolie interface

In order to allow for the publishing of a jolie operation in a REST modality it is necessary to annotate each operation of the interfaces to be published as it follows:

/**! @Rest: method=[post|get|put|delete] [,template=...]; */

where:

  • /**! [...] */ are the tokens to be used for making the comment to be interpreted by the tool

  • @Rest: is the token used for identify that the following operation must be imported as a REST method

  • method= it specifies which kind of method must be used for the REST importing

  • template= it specifies the template to be used for the given resource. It is worth noting that parameters must be specified within curl brackets as in the getOrders example in the demo folder.

Ex:

/**! @Rest: method=get, template=/orders/{userId}?maxItems={maxItems}; */

In this case the request type of the getOrders operation is like it follows:

type GetOrdersRequest: void {
   .userId: string
   .maxItems: int
}

The router automatically joins the parameters defined in the url {userId} and {maxItems} with the subnodes of the request message which have the same name. As an example the url:

http://localhost:8080/DEMO/orders/homer?maxItems=10

it will trigger the invocation of the target microservice on the getOrders operation with the following request message:

.userId = "homer"
.maxItems = 10

output of the tool

As output the tool produces a file called router_import.ol which must be copied inside the folder router in order to be automatically loaded by the router when it is run. Indeed, once copied router_import.ol into the folder router, it is sufficient to launch

jolie router.ol

for enabling the router. It is worth noting that the microservice published as a REST service into the router must running too. The router indeed, just interprets the REST requests message and forward them to the final microservice (which is the target microservice of the jolie2rest tool).

Options:

  • enable_swagger [ default = true ] This operation enables the creation of the related json swagger file which can be easily imported into Swagger (http://swagger.io/). Thanks to it, it is possible to invoke the rest apis from swagger.

  • easy_interface [ default = false ] This modality allows for skipping the usage of the router. It is useful when the microservice already provides a http port where its operations are available. In such a case, the microservice is already able to receive json messages and reply with json messages. In these cases, only the swagger json file is created where all the operations are automatically converted into POST calls. No annotations and templates are required in these cases. WARNING: the http protocol of the microservice must define the follwing parameters:

.response.headers.("Access-Control-Allow-Methods") = "POST,GET,OPTIONS";
.response.headers.("Access-Control-Allow-Origin") = "*";
.response.headers.("Access-Control-Allow-Headers") = "Content-Type"

Running the example

Pre-requisite: Prepare a web application for running a local instance of a Swagger UI (http://swagger.io/swagger-ui/). If you want to use jolie, you could download Leonardo web server (https://github.com/jolie/leonardo) and put the content of the SwaggerUI inside the folder www. Then launch jolie leonardo.ol in a separate shell and get the index.html page from your browser.

The example: Go into folder tools and launch the following command:

jolie jolie2rest.ol localhost:8080 swagger_enable=true easy_interface=false

Copy the file router_import.ol into folder router. Copy the file swagger_DEMO.json in the folder where your SwaggerUI application can retrieve it. If you are using Leonardo just put it inside folder www. Go into the folder tools/demo and launch the demo microservice:

jolie demo.ol

Open a new shell, go into the router folder and launch the router:

jolie router.ol

Open the SwaggerUI application with your browser and put the URL for retrieving the file swagger_DEMO.json inside the explorer text field . If you are using Leonardo put http://localhost:XXXX/swagger_DEMO.json, where XXXX is the port you chose for Leonardo.

Try to call your REST jolie service using the SwaggerUI.

tools/jolie_stubs_from_swagger

This tool allows for the creation of a jolie client for each path declared in a Swagger definition. Usage:

jolie jolie_stubs_from_swagger.ol url service_name output_folder

where:

  • url is the url where the swagger definition can be retrieved
  • service_name is the name of the service represented by the swagger definition
  • output_folder is the name of the folder where all the files will be created

Example:

jolie jolie_stubs_from_swagger.ol http://petstore.swagger.io/v2/swagger.json petstore petstore

Once executed the following files will be created in the output_folder:

  • outputPort.iol
  • list of all the clients (name_of_the_operation).ol

outputPort.iol contains the interface and the outputPort definition of the service described by the swagger definition. Such a file must be included in each microservice which aims at invoking the service described by the swagger definition.

In the example described above in the folder petstore it is possible to find the getOrderById.ol file. Try to open it and set the request message as:

with( request ) {
.orderId = 8
};

Then run the command

jolie getOrderById.ol

and look at the reply printed out in the console.

NOTE: Only application/json APIs are enabled so far

Router Admin

The router comes with a router admin service which is executed together in order to allow for a remote administration of the router. In particular, the router admin exposes three operations:

  • getRegisteredResourceCollections: it returns the list of all the registered resource collections into the router;
  • addResourceCollection: it adds a resource collection into the router;
  • removeResourceCollection: it removes a resource collection from the router;

The resource collections are expressed by means of a jolie interface declaration where the REST api templates are described as in the previous section "REST annotations on the jolie interface". The fully description of the operations may be consulted in the file RouterAdminInterface.iol which is located in the sub-folder router_admin/public/interfaces.

In the sub-folder router_admin/scripts there are three client scripts which allows for the interaction with the router admin operations.

WARNING: every time a resource collection is modified, the router requires to be restarted in order to get the modifications.

Available API list web application

A web application which uses some libraries from Swagger UI (http://swagger.io/swagger-ui/) is exeecuted together with the router and the router admin. It automatically reads the registered resource collections and it provides the list into a web application located at port 9082 by default. Thus, if you execute the web application on your localhost the URL is:

http://localhost:9082

Dockerization of the router

Jester can be easily dockerized by exploiting the Dockerfile distributed together with the source code. In order to achieve it, docker must be previously installed in the host machine then just follow these steps:

  • go into folder router;
  • run the command docker build -t jester . which locally creates the docker image of jester;
  • run the command docker run --name jester-cnt --net="host" -e JDEP_API_ROUTER="socket://127.0.0.1:9080" jester to run the container starting from the image just created;

The option --net="host" will allow the container to directly exploit the network of the host machine. If you want to limit the port exposition, remember that jester requires three main ports:

  • 9080: it is the http port of the router, all the REST APIs are available on it
  • 9081: it is the sodep port of the router admin, if you want to add, remove or get the list of the registered resource collections, you need to use it
  • 9082: it is the http port of the API list web application

The environment variable JDEP_API_ROUTER must be set to the location of the router as it is addressed from a final user, thus put the external IP and the exposed port number.