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Tag Archives: SOA

Web Service Communicator


The purpose of this article is to illustrate the potential of dynamic web service invocation made possible by Reflection.

This approach consists in: downloading the WSDL file at runtime, creating the proxy class, compiling it into an assembly and executing the methods on it.

This allows you to dynamically invoke methods from a web service that aren’t known at build time and potentially build pre-configured routines for message exchange between multiple services.


I had been looking for a couple of days about a way to dynamically invoke a web service without being bound to a prior knowledge of its contract at build-time.

As a result of my research I finally came across, which follows the approach that I’ve explained in the introduction.

I’ve built a simple Windows application which shows the potential of that approach to make web services communicate between them without a compile-time knowledge of their contracts.

Using the code

The sample solution includes two projects:

  • WSCommunicator.SL – Sample service layer
  • WSCommunicator.WinForm – Sample Windows Forms application

The Service layer contains a simple web service which returns some sample data. These are its methods

public List<Person> GetAllPersons()

public List<string> GetAllPersonsNames()

public int GetPersonsAge(string name, string surname)

public Address FindPersonsAdress(string name, string surname)

We will use these methods later to see how dynamic message exchange works.

The WinForm project contains one WinForm (“WSCommunicatorForm”) and some classes which are used for the dynamic web service invokation. The most important class is “WSInvoker” which uses System.Reflection to dynamically compile the web service descriptions into packages and call their methods.

This is how it achieves this:

private Assembly BuildAssemblyFromWSDL(Uri webServiceUri)
    if (String.IsNullOrEmpty(webServiceUri.ToString()))
        throw new Exception("Web Service Not Found");

    XmlTextReader xmlreader = new XmlTextReader(webServiceUri.ToString() + "?wsdl");

    ServiceDescriptionImporter descriptionImporter = BuildServiceDescriptionImporter(xmlreader);

    return CompileAssembly(descriptionImporter);

private ServiceDescriptionImporter BuildServiceDescriptionImporter( XmlTextReader xmlreader )
    // make sure xml describes a valid wsdl
    if (!ServiceDescription.CanRead(xmlreader))
        throw new Exception("Invalid Web Service Description");

    // parse wsdl
    ServiceDescription serviceDescription = ServiceDescription.Read(xmlreader);

    // build an importer, that assumes the SOAP protocol, client binding, and generates properties
    ServiceDescriptionImporter descriptionImporter = new ServiceDescriptionImporter();
    descriptionImporter.ProtocolName = "Soap";
    descriptionImporter.AddServiceDescription(serviceDescription, null, null);
    descriptionImporter.Style = ServiceDescriptionImportStyle.Client;
    descriptionImporter.CodeGenerationOptions = System.Xml.Serialization.CodeGenerationOptions.GenerateProperties;

    return descriptionImporter;

private Assembly CompileAssembly(ServiceDescriptionImporter descriptionImporter)
    // a namespace and compile unit are needed by importer
    CodeNamespace codeNamespace = new CodeNamespace();
    CodeCompileUnit codeUnit = new CodeCompileUnit();


    ServiceDescriptionImportWarnings importWarnings = descriptionImporter.Import(codeNamespace, codeUnit);

    if (importWarnings == 0) // no warnings
        // create a c# compiler
        CodeDomProvider compiler = CodeDomProvider.CreateProvider("CSharp");

        // include the assembly references needed to compile
        string[] references = { "System.Web.Services.dll", "System.Xml.dll" };

        CompilerParameters parameters = new CompilerParameters(references);

        // compile into assembly
        CompilerResults results = compiler.CompileAssemblyFromDom(parameters, codeUnit);

        foreach (CompilerError oops in results.Errors)
            // trap these errors and make them available to exception object
            throw new Exception("Compilation Error Creating Assembly!!\r\n" + oops.ErrorText);

        // all done....
        return results.CompiledAssembly;
        // warnings issued from importers, something wrong with WSDL
        throw new Exception("Invalid WSDL");

First a ServiceDescriptionImporter is built by parsing the web service WSDL. This is then compiled into an assembly which is ready to be used. This is how the WSInvoker calls its methods:

public T InvokeMethod<T>( string serviceName, string methodName, params object[] args )
    // create an instance of the specified service
    // and invoke the method
    object obj = this.webServiceAssembly.CreateInstance(serviceName);

    Type type = obj.GetType();

    return (T)type.InvokeMember(methodName, BindingFlags.InvokeMethod, null, obj, args);

In order to make data visualization possible on the client, an XML serializer (CustomSerializer class) is used which serializes the WS Output and loads a dataset with it, when possible. Here are the serialization-deserialization methods:

public String SerializeObject(Object pObject, Type myType)
        String XmlizedString = null;
        MemoryStream memoryStream = new MemoryStream();
        XmlSerializer xs = new XmlSerializer(myType);
        XmlTextWriter xmlTextWriter = new XmlTextWriter(memoryStream, Encoding.UTF8);
        xs.Serialize(xmlTextWriter, pObject);
        memoryStream = (MemoryStream)xmlTextWriter.BaseStream;
        XmlizedString = UTF8ByteArrayToString(memoryStream.ToArray());

        XmlizedString = changeInvalidCharacters(XmlizedString);

        return XmlizedString.Substring(1);
    catch (Exception ex) 
        throw new Exception("Serialization error!\r\n" + ex.Message); 

public Object DeserializeObject(String pXmlizedString, Type myType)
        XmlSerializer xs = new XmlSerializer(myType);
        MemoryStream memoryStream = new MemoryStream(StringToUTF8ByteArray(pXmlizedString));
        XmlTextWriter xmlTextWriter = new XmlTextWriter(memoryStream, Encoding.UTF8);
        return xs.Deserialize(memoryStream);
    catch (Exception ex)
        throw new Exception("Deserialization error!\r\n" + ex.Message);

The CustomSerializer is also used to serialize/deserialize the application configuration file which we’re going to examine further on.

The WSCommunicatorForm class defines the user interface. This is how it looks (click to expand):

user interface

The window is divided in two main parts: the left one contains the input web service configuration, the right one contains the output configuration and the input-output parameter mapping. When a valid web service url is entered into the left top textbox (Input web service) and the corresponding Load button is pressed, the Form calls the BuildAssemblyFromWSDL method of the WSInvoker class, which parsed the web service descriptor and acquires information on its definition and methods. The left part of the form is thus populated with the input web service information. By changing the web method selection, the corresponding return type information is updated to display the details of the currently selected method output.

There is also a textbox in which the input web service method parameters must be written separated by semicolon to allow a correct invocation of the web method.

A click on the left Invoke button invokes the selected method with the specified input parameters and displays the result on the left datagrid. I haven’t worked much on the data visualization aspect, as this is just a test application, but you should be able to see a result for most types of output.

When the result is displayed, the “Available Output Fields” listbox on the right gets populated with the column definitions of the left DataGridView. These items will later be mapped to the output web service input parameters.

If we now digit a valid web service url into the right top textbox (Output web service) and press the corresponding Load button, the right part of the form will be populated with the details of the output web service. This web service can even be the input web service, or any other which is reachable by the client machine. In the illustrated example the output web service is the same as the input one. This is how the window looks now (click to expand):

user interface populated

In order to make the message exchange possible between the two web services we need to configure the input-output mapping correctly. We can do this by using the arrows on the right side which allow us to move into the “Input parameters” listbox the available output fields obtained by the input web service. The parameters can also be moved up and down. The right-most listbox on the mapping section (Input types) contains the input parameter types for the currently selected output web service method. The number and the type of the input parameters must correspond to these types.

Once the mapping is done, we’re ready for the “magic” to happen: Press the right “Invoke” button to pass the input-web-service-output to the output web service method and see its output on the right DataGridView. This is how the window looks now (click to expand):

user interface populated

The application can save/load its configuration from XML. In order to make this simpler and make a creative use of the CustomSerializer I created some data structures in the WSComConfig.cs file as follows:

public struct WSComConfig
    public WSConfig wsInputConfig { get; set; }
    public WSConfig wsOutputConfig { get; set; }
public struct WSConfig
    public string wsAddress { get; set; }
    public string wsName { get; set; }
    public string wsMethod { get; set; }
    public List<string> wsParams { get; set; }

The CustomSerializer serializes this into (and deserializes this from):

<?xml version="1.0" encoding="utf-8"?>
<WSComConfig xmlns:xsi="" xmlns:xsd="">
    <wsParams />

This makes configuration loading and saving extremely easy. For this test application, the click handler on the “Load configuration” button automates the input-output configuration and the invocation of the input web service method, but leaves the final Invoke to the user. It obviously takes nothing to automate that too. This illustrates the potential of this approach to create automated web service message exchange routines!

Points of Interest

I learnt a lot through this project about dynamic web service invocation and explored dynamic web service mapping. Although the sample application illustrates communication between only two web services, this concept can be extended to an unlimited number of web services which can be configured to create a business process workflow. I have previously worked on the Java Open ESB and have been fascinated by its technology. This is surely less than 1% complex compared to it, but it makes web service interoperability possible.


I’d be very happy if someone takes this idea further

Click here to download the sample code from my Live Sky Drive

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A SOA approach to automatized DOCX-PDF report generation – part 1


With the advent of Ms Office 2007 Open XML formats, the philosophy of Office report generation was deeply changed into making it dettached from Office itself and open to any kind of programming language which is capable of reading compressed archives and manipulating XML. For further reading visit

In this article I’m going to illustrate a SOA approach for generating Docx reports in a distributed environment with the necessity of having Ms Office 2007 installed only on the developer machine (not the production server). The application is composed by the following parts:

  1. An ASP.NET web application
  2. An IIS-hosted WCF service
  3. A business tier
  4. A data access tier
  5. A database

The scope of this article is limited to the top 2 tiers. By using the Open XML SDK (now 2.0) it’s possible to programmatically read and write inside Office Open XML packages – that means reading and writing Office files without using Office COM objects. This approach is very fast, easy, light on resources and STABLE. The WCF service in this application must be able to create Docx reports on the basis of an existing docx template and some db data serialized as XML. Docx files are constructed in a modular way. To be able to appreciate this, you can just rename a docx file changing it’s extension to .zip. To know more about how this archive is organized visit The part that we’re interested in is called Custom XML (read The approach that’s best to follow for manipulating data within a Docx file is binding content controls to custom xml parts.

1. Generating a docx template document

The first thing to do is to build a docx document which defines the layout of the reports by using Word 2007 or above. In this document there are going to be static parts (text-blocks, images and so on) and dynamic parts, which are going to be dependent on the data. At first we build and format the docx file as we expect it to look with dynamic data on it. Then, when we’re happy enough with the way it looks, it’s time to add the content controls. On the Word ribbon we need to go to the Developer tab (if you don’t see it, click here to learn how to activate it). In this tab we can find a few content controls, such as rich text, plain text, image, etc. We now need to replace the fake data that we’ve put into the document with the appropriate content controls.

2. Creating Custom XML parts

Using Word 2007 we’re able to put Content Controls into a docx document, but we’re not able to bind those controls to custom data. In order to do this we need to use another tool called Word 2007 Content Control Toolkit. At this point our docx document doesn’t contain any custom xml parts. We can create these by using WCCT. Open the docx document inside WCCT. On the right panel click on “Create a new Custom XML part”. The custom XML part will be created and we’ll be able to see it from the “Bind view” tab. On the left part of the window we will be able to see references to the content controls that we’ve inserted in the file. Clicking on the “Edit view” of the right panel it’s possible to edit the xml. The xml structure that we need to create has to be valid and needs to correspond to the content controls in the page. For example

<title alias=”Title”>document title</title>
<body alias=”Body”>document body</body>

When we’ve finished creating the xml, it’s always good to get the xml syntax checked by WCCT clicking on the “Check Syntax” button. We’re now ready to go back to the “Bind View”. We will now be able to see the xml nodes we’ve just inserted in a tree-like structure and the fun part is about to begin. We’ll now bind the xml nodes to the content controls, and this is as easy as drag-and-drop. Select one of the nodes on the right panel and drag it on the reference to one of the content controls of the document. Repeat this operation for all of the xml nodes until all the content controls have been bound to data. When you’re done, save the file and click on the preview button to open the document using Word. Notice how the custom xml data has replaced the text inside the content controls.

3. Building the WCF service

The WCF service will replace the custom xml inside the docx template with business logic xml data. Using the Open XML SDK this is actually very easy. Here’s the replaceXML method

private void replaceCustomXML(string docxTemplate, string customXML)
using (WordprocessingDocument wordDoc = WordprocessingDocument.Open(docxTemplate, true))
MainDocumentPart mainPart = wordDoc.MainDocumentPart;


//Add a new customXML part and then add content
CustomXmlPart customXmlPart = mainPart.AddCustomXmlPart(CustomXmlPartType.CustomXml);

//copy the XML into the new part…
using (StreamWriter ts = new StreamWriter(customXmlPart.GetStream()))
catch (Exception ex)
throw new FaultException(“Errore WCF!\r\n” + ex.Message);

Once the docx document is created it will be sent to the client as an array of bytes.

public byte[] GenerateDynamicDocx(string customXML)
HttpServerUtility webServer = HttpContext.Current.Server;

// Copy template.docx in the temp folder to preserve the original copy
string tempFolder = webServer.MapPath(“temp”);
string tempDocxFileName = Guid.NewGuid() + “.docx”;
string tempDocxFilePath = tempFolder + @”\” + tempDocxFileName;
File.Copy(webServer.MapPath(@”App_Data/template.docx”), tempDocxFilePath);

replaceCustomXML(tempDocxFilePath, customXML);

byte[] docxContents = File.ReadAllBytes(tempDocxFilePath);

//Delete the temporary file

return docxContents;
catch (Exception ex)
throw new FaultException(“Errore WCF!\r\n” + ex.Message);

4. Building the ASP.NET client

The ASP.NET client will have a template.xml file which replicates the structure of the custom XML part in the server’s docx template. Ideally, there would be a web page which automatically generates web controls for inputing data which mirrors the structure of the xml template file. After the data is inputed the web client must compose an xml document which follows the structure of the existing template.xml but replaces the data with those inputed by the user. The xml string is then sent to the WCF service wich returns the bytes of the docx file. These bytes can then either be saved as a docx file on the server or sent directly to the client through HTTP.

Click here to download source code.

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