Node4Progress

Table of contents:

This documentations contains of the following sections:

1. Introduction

2. Features

3. Installation and configuration

4. Usage

   1. Using the handler approach

   2. Using the dynamic call approach

5. Code samples

6. The node4progress dataset object

   1. Object structure of the node4progress dataset object

   2. Installing and running the node4progress dataset examples

7. Troubleshooting

1. Introduction:

With node being the ascendant and "hot" technology of the day, the need arose to provide access to the business logic written in the PROGRESS 4GL from node. Node4Progress is the bridge that allows business logic procedures hosted on a PROGRESS appserver to be called directly from node.

2. Features:

Node4Progress provides 2 ways to access the appserver and 2 ways to consume the data.

• Ways of calling and appserver procedure

  1. Handler call

     • A handler program is an appserver procedure that implements a specific input-output parameter signature

  2. Dynamic call

     • Using this approach you can call any appserver procedure with any input-output parameter signature

• Ways of consuming the data

  1. As a JSON object

  2. As a dataset and/or temp-table object

     • Using this approach the data is consumed in a set of javascript objects that have similar attributes, methods and features as the PROGRESS prodataset and temp-table objects

All the features mentioned above will be covered in detail in the section "how to use"

3. Installation and configuration

Requirements:

To use the Node4Progress bridge the following components are required:

• Node version 10.28 and up

  • Java version 1.6 and up

  • appserver installation Progress version 10.2B and up

• Make sure that your login account has the necesary credentials to install node4progress

  • Preferably run the installation as root or as administrator

Out of the box node4progress comes with a set of examples configured to run against an appserver running on an amazon cloud computer. If you you just want to try out node4progress and you don't want to bother with having to set up an appserver to run the examples, you will be able to run the javascript example programs straight out of the box against the appserver running in the cloud. In this case just skip the installation steps below having to do with configuring and setting up the appserver.

Installation steps:

• Create a directory node4progressTest and make this directory the current directory

  • e.g.

    • mkdir /var/tmp/node4progressTest

    • cd /var/tmp/node4progressTest

• Type in the following command from the command line

  • for a global install

    • npm install node4progress -g

  • for a local install into the node4progressTest directory

    • npm install node4progress

After the install execute the following steps:

1. If you are using a global install for node4progress set to NODE_PATH environment variable to where node4progress is installed

   • On UNIX, LINUX and MAC this would most likely be

     • /usr/local/lib/node_modules

       • The command therefore would be

         • export NODE_PATH=/usr/local/lib/node_modules

2. Copy the files in the 4GlCode/BaseCode in the propath of your appserver

   • These programs must be accesible directly without having to specify a sub-directory

3. If you want to use the provided javascript examples

   1. Copy the 4GlCode/Examples directory into the propath of your appserver

      • They must be accessible as Examples/[program-name.p]

   2. Configure your appserver to connect to the sports database (not the sports2000 database)

4. Copy the javascript examples in the node_modules/node4progress/Examples directory into the node4progressTest directory

   • Make sure the config subdirectory with the configuration file config.json is copied over as well

     • Should result in the following directory structure for a local install

       node4progressTest/

       node4progressTest/config

       node4progressTest/node_modules

       node4progressTest/node_modules/node4progress

     • Should result in the following directory structure for a global install

       node4progressTest/

       node4progressTest/config

You are now able to run test examples against the Appserver running in the cloud:

• For example if you type in the following command

  node testDatasetCustomer.js

  • You should get the following result

Configuration steps:

Execute the following steps:

1. Pull the config/config.json file up in a text editor

   • The contents of this file look as follows:

   {
   "AppserverUrl":"APPSERVERDC://204.236.218.31:3190",
   "AppserverUserName": "",
   "AppserverUserPassword": "",
   "AppserverSessionModel": "State-less",
   "WinstoneSvrPort": 8087,
   "DateFormat":"mm/dd"
   } 
   

   • Configure the Appserver url, user name, password and session model to the correct parameters for you appserver

     • The appserver url must be in the following format

       • For an appserver connection routed through the name server

         • Appserver://[Host-name/Ip-address]:[NS-Port#]/AppserverNm

         • e.g. Appserver://localhost:5162/Sports

       • For a direct appserver connection

         • APPSERVERDC://[Host-name/Ip-address]:[Port-number]

         • e.g. APPSERVERDC://localhost:4090"

   • The WinstoneSrverPort needs to an available port on your local machine

     • Most likely you can leave this parameter alone

   • The DateFormat parameter controls how dates are going to be formatted

     • Use "mm/dd" for the American format

     • use "dd/mm" for the European format

Testing the configuration:

From the command line in the node4progressTest directory type in the following command:

• node configTest.js

Open up a browser and point to the following url:

• http://localhost:8085/TurboNode

If this results in a web page that looks like this then yoiur configuration is correct:

4. Usage

The node4progress module provides the following 2 ways calling business logic on the appserver:

1. Handler call

   • A handler is an appserver procedure that adheres to a specific input/output paremeter signature

2. Dynamic appsrever call

   • Using the dynamic appserver call approach you any appserver procedure with any input/output signature can be called

4.1 Using the handler approach

A handler is an appserver procedure with an input/output signature that looks as follows:

{dsOrder.i}

DEFINE INPUT  PARAMETER iInputPars  AS LONGCHAR   NO-UNDO. 
DEFINE OUTPUT PARAMETER oOutputPars AS LONGCHAR   NO-UNDO. 
DEFINE OUTPUT PARAMETER DATASET FOR dsOrder. 
DEFINE OUTPUT PARAMETER oErrMsg     AS CHARACTER  NO-UNDO.

• The suggested use for the 1st parameter (iInputPars) is to pass a set of input parameters as name value pairs

• The suggested use for the 2nd parameter is to pass a set of output parameters as name/value pairs

• The 3rd dataset parameter can be any valid dataset.

• The suggested use of the 4th parameter is pass an error message if the handler logic failed

The output parameters of the handler procedure are translated into a JSON structure passed as a string:

{
   "OutputPars": "...",   
   "ErrMsg": "...",
   "[DatasetNm]" : {...} 
}

In node the code for invoking a handler looks like this:

var conf = require("./config/config.json");
var node4progress = require("node4progressHttp")(conf);
var handler="handlers/CustomerHandler.p";
var inputPars = 'NumCustomersToPull=2';
node4progress.callHandler(handler,inputPars,true,function(err,result){
     console.log("CUSTOMER HANDLER RESULT");
     console.log(result);
     jsonObj=JSON.parse(result);
}); 

4.2 Using the dynamic call approach:

Invoking any appserver call with any parameter structure is a 3 step process:

1. Defining the appsever procedure to call using the setAppsvrProc method which takes the following input parameters

   1. ProcName

      • Program name of the appserver procedure)

   2. InternalProcName

      • Internal procedure name to call for a persistent appserver procedure

   3. IsPersistent

      • True when calling a persistent appserver procedure, otherwise false

   4. IncludeMetaSchema

      • If you want to use the node4progress dataset functionality pass true otherwise false

2. Defining each parameter using the setParameter method which takes the following input parameters

   1. ParName

      • Parameter name (controls how this parameter will be represented in the Json output)

   2. ParDataType

      • Datatype of parameter (character, integer, decimal, date, datatime, datetime-tz, dataset-handle, table-handle, longchar)

   3. ParIoMode

      • Input, output, input-output

   4. ParValue

      • For an input or input-output parameter you can pass the input value here. For a dataset-handle or a table-handle the input must be provided in write-json format

   5. SchemaProvider

      • When passing a dataset-handle or table-handle as input or input-output you must provide the name of a schema provider program. What a schema provider is will be explained below in a separate section

3. Executing the appserver procedure using the invoke method

   1. The only input parameter that the invoke method takes is the callback procedure which should have the following input parameters

      1. Error

         • If the appserver fails to execute, for instance because of a connection problem, then an error message explaining the problem will be passed in this parameter

      2. Result

         • The out parameters of the appserver procedure translated into a JSON string will be returned in this parameter

           • What this JSON structure looks like is explained below

Translating the output parameters of a dynamic appserver call into a JSON structure

The output of a dynamic appserver procedure looks as follows:

{
 "output" : {
              "CharOutputParameter"         : "...",
              "IntOutputParameter"          : 100,
              "DecOutputParameter"          : 210.50,
              "tableHandleOutputParameter"  : {...},
              "DatasetHandleOutputParameter": {...} 
            },
 "error"  : "...."
}

The important things to understand about this JSON structure are:

• At the root level of the JSON structure there are 2 nodes

  • "output"

    • Contains the contents of input-output and output parameters of the appserver procedure

      • In the order they are defined in the parameter signature

      • Table-handle and dataset-handle parameters are passed in write-json format

  • "error"

    • If an error occured while executing the appserver procedure (e.g. a appserver connection eror) then this parameter will contain error information

Using schemaproviders when passing a dataset-handle of table-handle as input

When passing temp-table data or dataset data as input in write-json format to an appserver procedure the table-handle or dataset-handle needs to have a metaschema structure before the appserver procedure is invoked. This as opposed to calling an appserver procedure that passes the data as output only where the metaschema structure can be inherited from the appserver program that is called.

So in order to call an appserver procedure that takes a temp-table of a dataset as input or input-output you need to create a schema provider procedure. A schema provider is a program that does nothing other than pass the structure of the dataset/temp-table as output.

Below is an example of a schema provider for a temp-table:

/*------------------------------------------------------------------------
 File        : CustUpdTt-SchemaProvider.p Purpose     :
 ------------------------------------------------------------------------*/
/ ************************  Definitions  *********************** / {Examples/CustUpdTt.i}
DEFINE OUTPUT PARAMETER TABLE FOR ttCustomer.

Below is an example of a schema provider for a dataset:

/*------------------------------------------------------------------------
 File        : CustUpdDs-SchemaProvider.p Purpose     :
 ------------------------------------------------------------------------*/
/ ************************  Definitions  *********************** / {Examples/CustUpdDs.i}
DEFINE OUTPUT PARAMETER DATASET FOR dsCustomer.  

5. Code Samples:

Code sample for calling a handler program:

var conf = require("./config/config.json");
var node4progress = require("node4progressHttp")(conf);
var handler="handlers/CustomerHandler.p";
var inputPars = 'NumCustomersToPull=2';

node4progress.callHandler(handler,inputPars,true,function(err,result){
    console.log("CUSTOMER HANDLER RESULT");
    console.log(result);
});

Code sample for a dynamic appserver call:

var conf = require("./config/config.json");
var node4progress = require("node4progressHttp")(conf);
node4progress.setAppsvrProc("Examples/CustUpdDs.p","",false,true);

node4progress.setParameter(
              "Imode",
              "character",
              "input",
              "GetCustomer",
              "");
node4progress.setParameter(
              "iInputParameters",
              "character",
              "input",
              "mode=FromTo|cust-num-from=1100|cust-num-to=9999","");
node4progress.setParameter(
              "dsCustomer",
              "dataset-handle",
              "input-output",
              "",
              "examples/CustUpdDs-SchemaProvider.p");
node4progress.setParameter(
              "oOutputPars",
              "character",
              "output",
              "",
              "");
node4progress.setParameter(
              "ErrMsg",
              "character",
              "output",
              "",
              "");
node4progress.invoke(function(err,result){
    console.log(result);
};

6. The node4progress dataset object

If data needs to be passed as input to an appserver procedure that expects either a dataset or a temp-table as input then it is essential that the data is presented to the appserver in exactly to correct format. For this reason node4progress provides a dataset object. If you interact with the data through the methods provided with the dataset object then the data will be maintained in exactly the correct format.

6.1 Object structure of the node4progress dataset object

Node4progress comes with a dataset object that is modelled after the PROGRESS prodataset object.

The node4progress dataset architecture comes with the following objects, attributes and methods.

+-----------------------+-----------------------+-----------------------+-----------------------+ | Object | Methods/Attributes* | **Purpose | Input Parameters | | | * | | | +-----------------------+-----------------------+-----------------------+-----------------------+ | Dataset | \$ | Returns a temp-table | ->TableName | | | | object: Example: | | | | | Tt=dataset.\$(TtName) | | | | | ; | | +-----------------------+-----------------------+-----------------------+-----------------------+ | | copyDataset | Returns a copy of the | ->isEmpty (when true | | | | dataset (optionally | an empty copy of the | | | | empty) | dataset is returned | +-----------------------+-----------------------+-----------------------+-----------------------+ | | emptyDataset | Removes all records | No input parameters | | | | from the dataset | | +-----------------------+-----------------------+-----------------------+-----------------------+ | | writeJson | Returns contents of | No input parameters | | | | the dataset as a JSON | | | | | string | | +-----------------------+-----------------------+-----------------------+-----------------------+ | TempTable | available  | returns true if a | No input parameters | | | | record in the | | | | | temp-table currently | | | | | has focus | | +-----------------------+-----------------------+-----------------------+-----------------------+ | | bufferCreate | Creates a record in | No input parameters | | | | the temp-table and | | | | | returns a buffer | | | | | object with the newly | | | | | created record | | +-----------------------+-----------------------+-----------------------+-----------------------+ | | bufferCopy | Copies the values of | ->CopySource | | | | a JSON object or a | -->Either a JSON | | | | buffer object passed | object or a buffer | | | | to the currently | object | | | | selected record | | +-----------------------+-----------------------+-----------------------+-----------------------+ | | bufferDelete | Deletes the currently | No parameters | | | | selected record from | | | | | the temp-table | | +-----------------------+-----------------------+-----------------------+-----------------------+ | | copyTempTable | Returns a copy of the | ->isEmpty (when true | | | | temp-table object | an empty copy of the | | | | (optionally an empty | temp-table is | | | | copy) | returned | +-----------------------+-----------------------+-----------------------+-----------------------+ | | emptyTempTable | Removes all records | No parameters | | | | from the temp-table | | +-----------------------+-----------------------+-----------------------+-----------------------+ | | forEach | Loops through the | ->callback (call | | | | records in the | back function that | | | | temp-table | will receive a buffer | | | | | object as input) | +-----------------------+-----------------------+-----------------------+-----------------------+ | | findFirst | retrieves the first | No input parameters | | | | record in the | | | | | temp-table and | | | | | returns a buffer | | | | | object with that | | | | | record | | +-----------------------+-----------------------+-----------------------+-----------------------+ | | findLast | retrieves the first | No input parameters | | | | record in the | | | | | temp-table and | | | | | returns a buffer | | | | | object with that | | | | | record | | +-----------------------+-----------------------+-----------------------+-----------------------+ | | writeJson | Returns a JSON string | No input parameters | | | | with the contents of | | | | | the temp-table | | +-----------------------+-----------------------+-----------------------+-----------------------+ | Buffer | \$ | Returns a bufferField | ->FieldNm (Field | | | | object | name of the buffer | | | | bufField=buffer.\$(fi | field to retrieve) | | | | eldNm); | | +-----------------------+-----------------------+-----------------------+-----------------------+ | | display | Returns a formmated | ->ListOfFields (a | | | | string with a number | list of fields to | | | | of fields that are | include in the string | | | | formatted as dictated | to formatted string | | | | by the format | to be returned) | | | | attributes in the | | | | | individual fields | | +-----------------------+-----------------------+-----------------------+-----------------------+ | | writeJson | Returns the contents | No input parameters | | | | of the currently | | | | | selected record as a | | | | | JSON string | | +-----------------------+-----------------------+-----------------------+-----------------------+ | BufferField | \$ | Returns the value of | ->AttributeNm (Name | | | | the requested | of the attribute to | | | | BufferField attribute | retrieve) | | | | (valid attributes are | | | | | buffer-value, value, | | | | | format, initial, | | | | | label & screenValue) | | +-----------------------+-----------------------+-----------------------+-----------------------+ | | bufferValue | Changes the | ->bufferValue (the | | | | BufferField value of | bufferField value to | | | | the currently | assign to this field) | | | | selected field | | +-----------------------+-----------------------+-----------------------+-----------------------+ | | setAttr | sets the value of a | ->AttrName (Name of | | | | BufferField attribute | the attribute to set) | | | | (valid attributes are | ->AttrValue (value | | | | buffer-value, value, | to set this attribute | | | | format, initial, | to) | | | | label & screenValue) | | +-----------------------+-----------------------+-----------------------+-----------------------+

6.2 Running the node4progress dataset examples

A set of examples is provided that show how to use the node4progress dataset object.

As explained before in paragraph 3 (installation and configuration) Node4Progress comes out of the box with a configuration that allows for these examples to be run against an appserver running on an Amazon clould computer. The examples are written to show some basic features of the dataset and then exit. Though generally the expected use of node4progress would be as part of a node based server process, stripping the examples down to the essentials seemed the shortest and easiest way to illustrate how to use the dataset.

The examples are centered around the following dataset features:

• How to navigate the data in a dataset object

  • testDatasetCustomer.js, testDatasetOrder.js, testDatasetInvoice

• Using the CallHandler approach

  • testCallHandler.js

• How to do a set of basic add, update, delete operations with a dataset

  • custAddDs.js, custUpdDs.js & custDeleteDs.js

• How to do a set of basic add, update, delete operations with a temp-table

  • custAddTt.js, custUpdTt.js & custDeleteTt.js

Each example lists in the header which dataset methods it uses and contains comments what each statement accomplishes.

For further instructions on how to get setup to run the examples please refer to paragraph 3.

7. Troubleshooting

The following are known issues that are currently being addressed:

• Known installation problems node4progress

  • Installation on Linux fails with message that node version is not supported for node4progress

    • On linux with the following node is generally installed with the following commands

      • To install node

        • sudo apt-get install nodejs

      • To install npm

        • sudo apt-get install npm

    • This may however not install the latest version of node that is needed (version 10)

      • You can get the version of node that is installed with the following command

        • node -v

    • If you do not have the latest version of node you can can iinstall it with npm with the following commands

      • sudo npm cache clean -f

      • sudo npm install -g n

      • sudo n stable

  • Node4progress install failed with a "shashum check failed" error

    • This is more likely to happen if you have had node installed for a while and have allready installed a number of other modules

      • In this case reset you npm configuration as follows:

        • npm cache clean

        • npm config set registry http://registry.npmjs.org/

        • npm set registry http://registry.npmjs.org/

      • Then try to install node4progress again with

        • On windows (run as administrator)

        • npm install node4progress

        • On Linux/Unix

        • sudo npm install node4progress

• On exiting a program that uses node4progress it sometimes takes a while for the winstone port to be released

  • This may result in the following error when you start up the program

    Exception: Error: connect ECONNREFUSED 
    Error: connect ECONNREFUSED 
        at errnoException (net.js:904:11) 
        at Object.afterConnect [as oncomplete] (net.js:895:19) 
    Exception: Error: socket hang up Error: socket hang up 
        at createHangUpError (http.js:1472:15) 
        at Socket.socketCloseListener (http.js:1522:23) 
        at Socket.EventEmitter.emit (events.js:117:20) 
        at TCP.close (net.js:465:12) 
    

    • This error resolves itself

      • When you run the program again the error will disappear

• Installing node4progress on linux gives an error