loopback-connector-soap

The SOAP connector enables LoopBack applications to interact with SOAP-based web services described using WSDL.

For more information, see the LoopBack documentation.

Installation

In your application root directory, enter:

$ npm install loopback-connector-soap --save

This will install the module from npm and add it as a dependency to the application's  package.json file.

Overview

There are two ways to use the SOAP connector:

• Use the LoopBack CLI lb soap command to automatically create a set of models based on a SOAP service WSDL file. Often, this will be the easiest way to connect to a SOAP web service, but may not be suitable for all applications. For more information, see SOAP generator.
• Write the code manually, calling the loopback-connector-soap and data source APIs directly. This is the approach illustrated here.

While both approaches use the loopback-connector-soap data source connector, they appear quite different.

SOAP data source properties

The following table describes the SOAP data source properties you can set in datasources.json.

Property	Type	Description
url	String	URL to the SOAP web service endpoint. If not present, defaults to the location attribute of the SOAP address for the service/port from the WSDL document; for example below it is http://www.webservicex.net/periodictable.asmx: <wsdl:service name="periodictable"> <wsdl:port name="periodictableSoap" binding="tns:periodictableSoap"> <soap:address location="http://www.webservicex.net/periodictable.asmx"/> </wsdl:port> </wsdl:service>
wsdl	String	HTTP URL or local file system path to the WSDL file. Default is ?wsdl. In the example above, it would be http://www.webservicex.net/periodictable.asmx?wsdl.
wsdl_options	Object	Indicates additonal options to pass to the SOAP connector, for example allowing self signed certificates. For example: wsdl_options: { rejectUnauthorized: false, strictSSL: false, requestCert: true, }
wsdl_headers	Object	Indicates additonal headers to pass to the SOAP connector, for example for sending http authorizations header. For example: wsdl_headers: { Authorization: "Basic UGVyc29uYWwgYWNjb3VudDpORVdsazIwMTVAKSEl" }
remotingEnabled	Boolean	Indicates whether the operations are exposed as REST APIs. To expose or hide a specific method, override with: <Model>.<method>.shared = true | false;
operations	Object	Maps WSDL binding operations to Node.js methods. Each key in the JSON object becomes the name of a method on the model. See operations property below.
security	Object	security configuration. See security property below.
soapHeaders	Array of objects.	Custom SOAP headers. An array of header properties. For example: soapHeaders: [{ element: {myHeader: 'XYZ'}, // The XML element in JSON object format prefix: 'p1', // The XML namespace prefix for the header namespace: 'http://ns1' // The XML namespace URI for the header }]
httpHeaders	Object	Custom HTTP headers. An object of header properties. For example: httpHeaders: { "custom-header": "value of custom-header", "custom-header-2": "value of custom-header-2" }

operations property

The operations property value is a JSON object that has a property (key) for each method being defined for the model. The corresponding value is an object with the following properties:

Property	Type	Description
service	String	WSDL service name
port	String	WSDL port name
operation	String	WSDL operation name

Here is an example operations property for the periodic table service:

operations: {
  // The key is the method name
  periodicTable: {
    service: 'periodictable', // The WSDL service name
    port: 'periodictableSoap', // The WSDL port name
    operation: 'GetAtomicNumber' // The WSDL operation name
  }
}

IMPORTANT: When using the CLI data source generator, you must supply the "stringified JSON" value for this property. For example:

{"getAtomicWeight":{"service":"periodictable","port":"periodictableSoap","operation":"GetAtomicWeight"},"getAtomicNumber":{"service":"periodictable","port":"periodictableSoap","operation":"GetAtomicNumber"}}

To generate the stringified value, you can use the following code (for example):

var operations = {
  "operations": {
    "getAtomicWeight": {
      "service": "periodictable",
      "port": "periodictableSoap",
      "operation": "GetAtomicWeight"
    },
    "getAtomicNumber": {
      "service": "periodictable",
      "port": "periodictableSoap",
      "operation": "GetAtomicNumber"
    }
  }
};

var stringifiedOps = JSON.stringify (operations);
console.log(stringifiedOps);

security property

The security property value is a JSON object with a scheme property. The other properties of the object depend on the value of scheme. For example:

security: {
    scheme: 'WS',
    username: 'test',
    password: 'testpass',
    passwordType: 'PasswordDigest'
}

Scheme	Description	Other properties
WS	WSSecurity scheme	username: the user name password: the password passwordType: default is 'PasswordText'
BasicAuth1	Basic auth scheme	username: the user name password: the password
ClientSSL	ClientSSL scheme	keyPath: path to the private key file certPath: path to the certificate file

1 currently unsupported, use "wsdl_headers": { "Authorization": "Basic …" }, instead, details: issue #92.

Creating a model from a SOAP data source

Instead of defining a data source with datasources.json, you can define a data source in code; for example:

ds.once('connected', function () {

  // Create the model
  var PeriodictableService = ds.createModel('PeriodictableService', {});

  // External PeriodTable WebService operation exposed as REST APIs through LoopBack
  PeriodictableService.atomicnumber = function (elementName, cb) {
    PeriodictableService.GetAtomicNumber({ElementName: elementName || 'Copper'}, function (err, response) {
      var result = response;
      cb(err, result);
    });
  };
...
}

Extending a model to wrap and mediate SOAP operations

You can extend a LoopBack model to wrap or mediate SOAP operations and define new methods. The following example simplifies the GetAtomicNumber operation:

periodictableperiodictableSoap.GetAtomicNumber = function(GetAtomicNumber, callback) {
    periodictableperiodictableSoap.GetAtomicNumber(GetAtomicNumber, function (err, response) {
      var result = response;
      callback(err, result);
    });
}

Creating a model from a SOAP data source

The SOAP connector loads WSDL documents asynchronously. As a result, the data source won't be ready to create models until it's connected. The recommended way is to use an event handler for the 'connected' event; for example as shown below.

Once you define the model, you can extend it to wrap or mediate SOAP operations and define new methods. The example below shows adding a LoopBack remote method for the SOAP service's GetAtomicNumber operation.

...
ds.once('connected', function () {

  // Create the model
  var PeriodictableService = ds.createModel('PeriodictableService', {});

  // External PeriodTable WebService operation exposed as REST APIs through LoopBack
  PeriodictableService.atomicnumber = function (elementName, cb) {
    PeriodictableService.GetAtomicNumber({ElementName: elementName || 'Copper'}, function (err, response) {
      var result = response;
      cb(err, result);
    });
  };

  // Map to REST/HTTP
  loopback.remoteMethod(
      PeriodictableService.atomicnumber, {
        accepts: [
          {arg: 'elementName', type: 'string', required: true,
            http: {source: 'query'}}
        ],
        returns: {arg: 'result', type: 'object', root: true},
        http: {verb: 'get', path: '/GetAtomicNumber'}
      }
  );
})
...

Example

For a complete example using the LoopBack SOAP connector in LoopBack 4, see SOAP calculator tutorial.