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Designing Visio Automation Solution

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Designing Visio Automation Solution

Overview & Scope

This document describes suggestive approach for designing solutions which involve office automation using Microsoft Visio. Shared are the learning derived from successful delivery of Managed Solutions project – ‘ServiceMap’. Scope of the document is not to cover on explaining design patterns, instead illustrates how applying relevant patterns help building effective solution.

Architecture & Framework

 

Technology evaluation

Microsoft Visio is diagramming and information visualization tool for modeling business and technical diagrams. Visio provides drawing control tied with SDK for programming. DotNet windows form application hosting Visio drawing control will provide canvas-like drawing surface. Visio drawing functionalities can be implemented using Visio’s SDK which makes programming more API model driven and hence increases developer’s productivity. Visio shapes has shape sheet which allows developer to add custom attributes to the shape. Persisting custom attributes is achieved as and when the Visio document is saved. Shape also have data linking facility by which external data source like share point list or database can be connected and data can be linked to the shape inside the drawing. In-built shapes or user defined shapes can be created and added to Visio stencil to hold list of master shapes which can be used while drawing.

Base framework

The base framework to interpret user interaction with the designer surface is via ‘Command Pattern’ and the concern of separation between the view and core operation logic is through ‘Presentation Model’.

View: Contains the windows form which hosts the Visio drawing activex control as designer surface. The view also includes interactive menu bars / tool strips and context sensitive menu items. View includes other windows like managing attributes of shapes, setting color to shapes, panning and Zooming window.

Model: Contains command handler classes which realizes the Execute() method of ICommandHandler interface. Each command handler is associated to command(s), accepts Event Argument as parameter and perform respecting operational logic.

PresentationModel: Contains instance of view. Each view (windows form) creates their own instance of Presentermodel and passes view (themselves) as parameter to presentermodel. Presenter model is view specific which contains Command Invoker that prepares event arguments and invokes model’s command handler.

 

Object model graph

Need for object model graph:

Programming model limitation with Visio is to arrive at relation between shapes. Two shapes can be connected by a connector and this linked relation does not imply underlying business relationship like parent-child / tree / hierarchy. Diagram has list of shapes; shapes are either linked or overlapped to show relation among them. Hence there is need to capturing an in-memory object model which can depict both individual shape’s instance and relation with other linked shapes.

What does object model contain?

A Visio shape is mapped to .net entity object which could hold ID of the shape and shape collection which holds list of children shapes. This collection can hold related shapes / children shapes / overlapping shapes based on the nature of drawing and its business need. Along with it, the shape entity can have programmer friendly methods like add, delete, find, sort methods on the shape collection. To add more business dependent logic, custom events can be introduced to shape entity which will trigger events on add/delete operations (as per requirement).

How is object model graph created?

Whenever a new shape is added to the drawing surface, in the corresponding event handler an instance of shape entity class is created passing the shape’s unique Id. When children shapes are added to a shape, list of children shape entities are created and added to parent shape instance’s shape collection. Similar is delete functionality.

Visio features

 

Visio active-x drawing control

The Visio Drawing Control is a Microsoft ActiveX control that provides full access to the Visio object model (API) and user interface so that you can integrate the Visio user interface, customize its appearance, and automate Visio in your applications. The Visio Drawing Control is provided with both Microsoft Office Visio Standard 2007 and Microsoft Office Visio Professional 2007, and is installed when you install Visio. Microsoft Office Visio 2007, or another version of Visio that supports the Visio Drawing Control must be installed on any computer where the Visio Drawing Control will be used. When you distribute your application, all users must have licensed copies of a version of Visio that supports the Visio Drawing Control on their computers to use it. To gain access to the Visio object model, use the Window or Document property of the Visio Drawing Control. Once you have access to the Visio object model, you can use all the standard objects, methods, properties, and events of the model to automate and customize the control in your program.

Out-of-the-box features

Most of the drawing capabilities and other related features provided by Visio can be achieved using Visio SDK and drawing control.

Pan & zoom

Visio’s Pan & zoom window can be incorporated to your custom application. Panning / zooming performed through this window will reflect changes of underlying drawing control.

Hyperlinks

Shapes dropped into drawing control can have hyperlink(s). Adding hyperlink can either be a file or url. Multiple links can be added and can be made available in the right click context menu. Follow command will help navigating to the respective hyperlink.

Export to feature

Document object provides SaveAs and Export functions through which the drawing can be saved into multiple formats like VSD, VDX, JPEG, etc. Using Save As Web API, the drawing can be exported to HTML file which has rich client scripting added to it that provides pan/zoom, search shape, view shapes’ attributes and hyperlinking features enabled on the exported file.

Visio XML schema

Visio drawing can be saved in binary format VSD file. Alternatively, it support saving into xml format as VDX file which follows Visio XML Schema. This allows reading and manipulating content of the drawing through programming. Also, the VDX format provides flexibility and support to save custom data into the SolutionXML tag. The VDX file can contain multiple solution xml tag which should be uniquely named and can have well formed XML content in it. Saving your custom application related information can be achieved using get / set solutionxml methods of Document object.

Custom features

Layout management

Aligning & positioning shapes or group of selected shapes in a page is available in Visio. But this requires additional programming. Methods like CentreDrawing, Layout and properties like ResizePage are used based on need to manage layout along with applying styles like Hierarchy or flowchart to arrange shapes. Arranging based on selected style also ties up with direction like Left to right, top to down etc. Moreover, style to connectors can also be set namely, straight or curved. Based on nature of drawing and how shapes are linked, programming arranging and positioning shapes are bit complexity involved and needs care.

Expand / collapse

Object model graph plays vital role in implementing many features which cannot be achieved out-of-the-box using Visio APIs. Since object model graph can be traversed and searched through, when user selects a shape and collapses it, all children shapes are moved to a layer which is marked visible = false. Every page has two default layers – one for the shapes and other for connectors. Create new layer and hide it. Move the list of shapes under selected parent from default layer to hidden layer on collapse command. Note, the object model graph still has the relationship maintained in it alive. When user selects a collapsed shape and calls expand, find list of children shapes to the selected parent shape from object model graph. Move these shapes from hidden layer back to default layer. Using Layers in Visio and in-memory object model graph helps achieving this feature which is not available in Visio.

Note: similar logic can be applied to create a tree view of all shapes in a separate window where each node in tree view maps to shape in the drawing. For example: showing WBS items in a tree view for an elaborate Work breakdown structure diagram.

Architectural Extension

 

Service Map to Service Catalog

Service Catalog is server component to manage list of service maps in the organization. From service map designer, user can load / publish / edit a service map in is hosted on service catalog. Service catalog exposes WCF service with BasicHTTP binding and is hosted on IIS along with service catalog website. Service Map .NET 2.0 client consumes WCF service by adding web reference to service. Dedicated Command Handler in service map’s model will perform communication with service catalog web service.

Designing Visio Automation Solution.docx

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