Single Middleware Frontend

A middleware that can transform, modify and forward requests based on pre-defined configuration. It allows you to modify your client request such as add, modify, or delete key-value, transform your request into JSON or XML and send the response back to the client. Execute Request configuration as a serial or parallel request

Prerequisite

1. Create a project folder inside configures folder. Take a look inside configures.testing/test-1.
2. Inside a project folder create file configure.json, base.json, serial/parallel.json. configure.json can be renamed to anything.
3. Create src/.env file (see src/.env.example file).
4. Specify the path to the configures directory in .env (see src/.env.example file) .

See configures.testing directory structure for examples.

Running set up

1. Create configure directory, along with projects and configuration file, and router.json
2. Specified your configure directory location in env
3. Change working directory to src and run :

go build -o ./build/go-single-middleware ./cmd/.

4. Run the program :

./build/go-single-middleware

Running using docker

Set up Docker Container and Network

1. Create docker network called proxy_middleware_net by running :

   docker network create --driver bridge proxy_middleware_net
   

2. Check if docker network have been created by running docker network ls :
3. Change working directory to where src located
4. Run docker-compose build
5. Run docker-compose up
6. Check if container have been assigned to network proxy_middleware_net by running docker network inspect proxy_middleware_net

Set Up Proxy Container and Postman

1. run docker run -d --name='proxy-middleware' -p 8000:8888 dannydirect/tinyproxy:latest ANY
2. Make sure that proxy-middleware is running :
3. Configure postman proxy, by settingproxy server to 0.0.0.0 and proxy port to 8000 :

Make a request through proxy

1. Check your container name and router
2. To make a request, just enter url http://<container name>/<path> and hit send. Make sure container proxy-middleware is running and postman proxy settings have been set up.

File Base.json

{
  "project_max_circular" : 10,
  "circular_response" : {
    "status_code" : 508,
    "adds" : {
      "body" : {
        "message" : "Circular request",
        "error" : "circular request detected"
      }
    }
  }
}

project_max_circular

Specify maximal number of circular request. This can be happen if configure-1 refer to configure-2 but configure-2 refer to configure-1.

circular_response

Specify response to be returned if circular request has reached project_max_circular.s

File Router.json

In order to make request to this middleware, take a look inside configures.testing/router.json.

• path : Client to middleware endpoint.,
• project_directory : Project directory path relative to router.json,
• type : Make a serial or parallel request. The default value is serial if value is empty. Middleware will read related files (serial/parallel.json)
• method : Client to middleware request method.
  Available values are
  • GET
  • POST
  • PUT
  • DELETE

Path parameter

If you want to use path parameter from Client to middleware, you can use /:key.

For example, if middleware make a request with POST method to middleware at http://localhost:8000/smsotp/generate/25 for project smsotp, and then make a request from middleware to destination as a serial request :

[
  {
    "path" : "/smsotp/generate/:smsId",
    "project_directory" : "smsotp",
    "type" : "serial",
    "method" : "POST"
  }
]

File Serial.json

Execute request sequentially. This json structure accept list of configures. for example:

{
  "configures": [
    {
      "file_name": "test-1_configure-0.json",
      "alias": "$configure_test-1",
      "failure_response": {
        "status_code": 500,
        "transform": "ToJson",
        "adds": {
          "body": {
            "error_message": "Request Logic error or there is something error"
          }
        }
      },
      "c_logics": []
    }
  ]
}

file_name

Specify configure file name

alias

Specify alias for configure file name. Must contain prefix $configure

failure_response

Specify response if all logic fail

c_logics

Accept list of json logic structure, based on https://jsonlogic.com/operations.html for example :

    {
          "rule": {
            "==": [
              "$configure_test-3_2--$request--$query[movie_id]",
              550
            ]
          },
          data : null,
          "response":null,
          "next_success : null,
          "next_failure": null,
          "failure_response : null
        }

rule

Json logic operator/rule.

data

Json logic data.

response

Return response if logic is true.

failure_response

return response if logic is false.

next_success

specify configure alias to be processed if logic is true. Response must be null.

next_failure

specify configure alias to be processed if logic is false. Response must be false.

Note

If cLogics is empty, return last configure executed response.

next_success or next_failure in file parallel.json value only accept serial.json or parallel.json, cannot refer to other configure

File Parallel.json

Execute request simultaneously. See example configures.testing/test-6.3 .

failure_response

response to be returned when all logic is fail.

configures

List of configuration file.

file_name

configure file name.

alias

configure alias. Must contain prefix $configure.

c_logics

check logic after all parallel request processed.

File Configure.json

Request to destination endpoint

For each configure file in your project directory, it represents a request.

1. Specify the target URL for request

In order to forward your request, the middleware need to know the destination url and destination path.

1. Specify destinationUrl in configure file
2. Specify destinationPath in configure file
3. The final endpoint is : destinationURL + destinationPath

2. Specify the request method

You must specify your request method for key method in configure file. The following values are available : (UPPERCASE) :

• GET
• POST
• PUT
• DELETE

3. Transform your request

You can transform your request to JSON or XML. By default, the middleware will transform your request to JSON format. You can specify your request format for key transform in configure file. The following values are available :

• ToJson to transform your request to JSON format.
• ToXml to transform your request to XML format

If a request/response don't have any wrapper for the body and you want to convert it to xml, it automatically wrap your request with such that (body) , because this middleware use package clbanning/mxj,

For example if you send an empty request to the middleware, and your configuration for request like below and you want to transform it to XML :

  "request": {
    "destinationPath": "/",
    "destinationUrl": "http://localhost:3001",
    "transform": "ToJson",
    "logBeforeModify" : "",
    "logAfterModify" : "",
    "adds": {
      "header": {
      },
      "body": {
        "name" : "nicholas",
        "last_name": "anthony"


      },
      "query": {
      }
    },
    "modifies": {
      "header": {

      },
      "body": {

      },
      "query": {
      }
    },
    "deletes": {
      "header": [
      ],
      "body": [
      ],
      "query": [
      ]
    },
    c_logics : [],
  },

The middleware will add name and last_name to the body, but because the request don't have any wrapper element, your request will be :

<doc>
    <last_name>anthony</last_name>
    <name>nicholas</name>
</doc>

If you want to pick the value from this configure, for example name, you have to mention the doc like $body[doc][name] .

4. Request modification

Middleware will do addition, modification, deletion sequentially. Request modification can be performed for header, body, and query.

4.1 adds

You can add key-value to your request, by specify key and value. You can also add key-value to a nested object by using ".(dot)", or directly add a nested object. If the object is not exist, the middleware will create it for you. In this example, we will add key id , name and favourite_cars property to a nested object user to a request body using dot syntax, add nested object address.

"adds": {
      "header": {
      },
      "body": {
          "id" : "123",
          "user.name" : "nicholas",
          "user.favorite_cars": [
              "honda",
              "fiat",
              "toyota",
              "ferrari"
          ],
          "address" : {
              "city" : "bandung",
              "province" : "west java"
          }
      },
      "query": {}
    },

####4.2 modify You can modify your request by specify key-value pair in modify . In order to modify a certain key from your request, key must already existed* in your request. The following examples shows that we want to modify id and modify name from nested object user.

    "modifies": {
      "header": {
      },
      "body": {
        "id" : 456,
        "user.name" : "anthony"
      },
      "query": {}
    },

Note : key-value for request header and query cannot be a nested object

4.3 deletes

To delete keys from your request, you can specify it in deletes. The following example shows that we want to delete name property from nested object user, and we want to delete id.

    "deletes": {
      "header": [],
      "body": [
           "id",
           "user.name"
      ],
      "query": []
    }

Note : You can also delete an entire object, for example, replace user.name with user, you will delete object user from your request.

4.4 c_logics in request

Check logic before sending request. If logic is false, you can specify failure_response to return response or next_failure execute next config. In serial request, if failure_response and response not specified, middleware will return serial failure_response for current processed configure that has been specified in serial.json. In Parallel request, middleware will return failure_response that has been specified in parallel.json. Middleware will not send any request. If logic is true, you can specify response to return response or next_success to execute next config. If response and next_success not specified, middleware will send request.

    "c_logics": [
      {
        "rule": {
          "and": [
            {
              "==": [
                "$configure_test-4_0--$request--$query[movie_id]",
                550
              ]
            },
            {
              "==": [
                "$configure_test-4_0--$request--$query[movie_id2]",
                384018
              ]
            }
          ]
        },
        "data" : null,
        "response" :  null,
        "next_success" : "$configure_test-4_1",
        "next_failure" : null,
        "failure_response" : null
      }
    ]

5 Modify response from each request.

You can modify response from each request but only for body and header, the rules are the same like request modification.
Note : key-value for response header cannot be a nested object

6. Get a value between each configure

To pick a value between each configure, you must consider from which configure you want to pick the value, whether your value located in :

• request header, body, query, or path parameter
• response body or header

For example, if our configure1.json want to pick name from nested object user which located in response body in configure0.json, we can write :

$configure0.json--$request--$body[user][name]

If you want to pick a value from array, for example if the request from configure0.json has cars in the nested object user and the value is ["toyota","honda","hyundai"], then we can pick toyota like the following code :

$configure0.json--$request--$body[user][cars][0]

Notice that each section is separated by double dash (--). That's why you can't use double dash for configure file name.

Consideration to pick a value between each configure

1. If you use serial route, you can only pick the value from previous configure, you can't pick the value from configure2.json the middleware execute the request sequentially. For example, you can pick a value for configure1.json from configure0.json request or response, you can't pick a value from configure3.json. This is because configure0.json is the first index in configures directory, following by configure1.json, and last configure3.json.

Remember that the order of configure-n.json file in configures directory is really important for serial route

2. If you use parallel route, you can't pick the value between each configure because the middleware execute the request simultaneously. For example, you can't pick a value for configure1.json from configure0.json request or response.

7. Logging

You can log header, body, query, path parameter from each configure file by specifying value for keys :

• logBeforeModify : This will log a value before change/modify request/response.
• logAfterModify : This will log a value after change/modify request/response.

Following values are available:

• $body
• $header
• $query
• $path

Or if you want to log specific value, you can specify it like this: $body[user][name].

Example :

"logBeforeModify" : "$body", // this will log the whole body before doing any change.
"logAfterModify" : "$body[user][name]" // this will log name from object user after doing change.