After a long hiatus I finally have some time to start blogging again. This time I hope be more frequent in my postings. A lot has happened since my last post including the formal release of V1.0 of the UA SDK and the most recently posted V1.1 Beta. Although these things are good it does mean the number of different downloads available on the website is piling up so I thought it would be a good idea to provide a short road map for people interested in UA. I have organized the road map based on the common queries I get.
1) I know nothing about UA and I am looking for a somewhere to start.
For people looking for a good introduction to UA concepts I recommend the video/audio presentations from UA DevCon 2007. They can be found here.
2) I want to read the specifications but I don't want to read 13 documents.
The substance of the UA specification is defined in Part 3 and Part 4. If you read those you will learn about how the UA information model works and the services that can be used to access it.
However, Parts 3 and 4 are technology independent abstract specifications. If you want to understand the technology used to build a UA application you need to read Part 6. This document defines, among other things, the UA-TCP protocol and how to implement UA with XML Web Services.
Part 7 breaks the specification apart into concrete, testable features.
3) I am a developer and want to see code that can get me started.
For coders looking for a simple starting point there are a series of Quickstarts available. Each Quickstart contains one or two simple applications which focus on a particular feature. For example, the Data Access Quickstart contains a client and server that implement nothing more than the features which you would see in a COM DA application (e.g. browse, read, write, subscribe). The Alarm Condition Quickstart provides the equivalent based on COM AE applications.
4) I have a development environment that allows me to ingest a WSDL and start writing code.
The WSDL is available here. The numeric identifiers assigned by the specifications are available in CSV form here and status codes can be found here. A WCF sample built by using the WCF tools to ingest the WSDL can be found here. The WCF sample does not use any code from the SDK and it implements the features required for a basic data access UA client and server.
5) I have started to use the .NET SDK and I am looking for documentation
The .NET SDK help is available online and it includes some pages on the overall architecture. The file is also available as downloadable help file (aside: Windows thinks help files are dangerous so you will need to unblock the file after downloading via the file properties dialog).
The Quickstarts all have their own help file which describe how the use the SDK features.
6) I need to develop C/C++ applications.
The ANSI C stack source code is part of the SDK source download but it is also available in separate package which does not include the .NET SDK. There is an ANSI C Quickstart which provides simple C++ client and server applications. These applications illustration how to create a session and read a value.
7) I need to develop Java applications.
The Java stack is available from the OPC Foundation here.