• Dan Driscoll's Blog

    WSDAPI 101 Part 5: Putting it all together to generate WS traffic

    • 23 Comments
    This is the fifth article in the WSDAPI 101 series. You'll learn the most by starting at the beginning, although it's not required to understand the content in this article. Now that we know all about the pieces required in a device-oriented Web Services...
  • Dan Driscoll's Blog

    WSDAPI 101 Part 1: Web Services from 10,000 feet

    • 5 Comments
    Introduction to WSDAPI 101 The world of Web Services (WS) is often described in terms of contracts, messages, and generated code. The picture that’s painted gives a high-level overview of the interactions between clients and services; but in describing...
  • Dan Driscoll's Blog

    UUID URI schemes

    • 0 Comments
    UUIDs (related to GUIDs ) are used frequently in computing applications. If you don't know these by name, you will probably recognize the 128-bit value in the format in which it is typically rendered: 7673868d-231e-490d-9c4f-19288e7e668d This...
  • Dan Driscoll's Blog

    xAddrs optionality in WS-Discovery messages

    • 5 Comments
    Traditional big web services, like a billing system or a service running in the cloud, nearly always have fixed addresses--often HTTP URLs. Smaller web services, such as those on a PC or a device, often have logical identifiers ("urn:uuid:c3de740f-9227...
  • Dan Driscoll's Blog

    WSDAPI 101 Part 3: Generated code and what it does for you

    • 6 Comments
    This is the third article in the WSDAPI 101 series. You'll learn the most by starting at the beginning, although it's not required to understand the content in this article. Now that we understand the layering presented in WSDAPI 101: Part 2 , we can...
  • Dan Driscoll's Blog

    WSDAPI 101 Part 4: The interfaces under the generated code

    • 4 Comments
    This is the fourth article in the WSDAPI 101 series. You'll learn the most by starting at the beginning, although it's not required to understand the content in this article. WSDAPI 101 Part 3 was all about that cool adapter layer that sits between...
  • Dan Driscoll's Blog

    What's the deal with WSDAPI's WS-Discovery interfaces?

    • 0 Comments
    I briefly discussed WSDAPI's WS-Discovery interfaces in part 4 of WSDAPI 101 , but I didn't describe in detail which interface to use to solve a specific problem. So to fill in that gap, I'll cover each of the situations that map to these objects and...
  • Dan Driscoll's Blog

    Whitepaper for DPWS, WS-Discovery, and SOAP-over-UDP

    • 4 Comments
    We've just published a whitepaper on DPWS, WS-Discovery, and SOAP-over-UDP over at MSDN. This is a great guide for those of you who want a good technical introduction to how all three specifications work. Special thanks go to Ram Jeyaraman for doing...
  • Dan Driscoll's Blog

    WSDAPI 101 Part 2: The stack, explained through a concrete example

    • 0 Comments
    This is the second article in the WSDAPI 101 series. You'll learn the most by starting at the beginning, although it's not required to understand the content in this article. The first article in the WSDAPI 101 series presented an overview of the actors...
  • Dan Driscoll's Blog

    When in doubt, use QueryInterface to convert your pointers

    • 3 Comments
    I'm sure you've had enough of attachments by now, so I'm going to talk about something entirely different: how WSDAPI base interfaces work on objects that have multiple derived interfaces. You know, like IWSDAttachment. Oops. Here's the deal: WSDAPI...
  • Dan Driscoll's Blog

    Help! How do I send extensible data in my WS-Eventing Subscribe?

    • 5 Comments
    Reader Nitin raises a good question: how does an app put extensible data into the Subscribe message that's used to set up events? Example scenario: WSD Scan Nitin's question asks specifically about the WSD Scan protocol built into Vista and Servier...
  • Dan Driscoll's Blog

    Web Services stacks on Windows

    • 6 Comments
    It has never been particularly easy to choose a Web Services stack on which to build your application. Microsoft has produced many over the years (for example, WCF and WSDAPI) and other software vendors produce even more. The feature sets of these stacks...
  • Dan Driscoll's Blog

    WSDXML and WSDAPI's DOM sections

    • 4 Comments
    As I promised in my last post , here's a guide to the WSDXML_* structures used in DOM processing in WSDAPI. Before I get started, a quick statement on DOM: Document Object Model is a way of representing XML nodes as static structures in memory. The structure...
  • Dan Driscoll's Blog

    DPWS, WS-Discovery, and SOAP-over-UDP entering standardization

    • 0 Comments
    Last week OASIS announced the formation of a technical committee to standardize DPWS, WS-Discovery, and SOAP-over-UDP. This is big news for all three specifications (and the people who implement and rely on them), as it gives us an opportunity to collaborate...
  • Dan Driscoll's Blog

    Using MTOM to set up binary streams

    • 0 Comments
    The SOAP Message Transmission Optimization Mechanism is a building-block spec that DPWS profiles so that specifications built on top can use it in a consistent and device-friendly way. MTOM isn't used in any of DPWS's messages, but it is available to...
  • Dan Driscoll's Blog

    Help! WSDAPI crashes after my service method returns!

    • 7 Comments
    I'm going to take a quick detour from WSDAPI 101 to comment on an issue you may have seen when developing and testing a service or client based on WSDAPI. The symptoms of this crash This problem may arise in two scenarios: You have a service...
  • Dan Driscoll's Blog

    Relationship metadata

    • 0 Comments
    The Devices Profile for Web Services isn’t exactly a Profile in all senses of the word. Yes, it does select and constrain underlying specifications like SOAP and WS-Discovery, but it also does very un-profile things like define schema. One of the things...
  • Dan Driscoll's Blog

    Discovery-layer types in DPWS applications

    • 3 Comments
    The roles of Types in WS-Discovery messages is really clear for generic, non-DPWS services. Types are qualified names expressed in the <d:Types> element of WS-Discovery messages, and these names identify a set of operations; the service advertised...
  • Dan Driscoll's Blog

    Help! I can't write to my attachments!

    • 2 Comments
    Another day, and another detour from WSDAPI 101 . Today's article comes courtesy of WSDAPI's attachment interfaces, which are often the subject of questions I receive from fellow developers. In specific, I'm talking about: IWSDOutboundAttachment...
  • Dan Driscoll's Blog

    Acronym soup

    • 0 Comments
    Those of you working in or around Web Services (or those of you who just read my blog for sheer excitement) have probably seen acronyms like DPWS and WSDAPI tossed around. Some of these are pretty straightforward, but the interplay between them is subtle...
  • Dan Driscoll's Blog

    WS-DD v1.1 specs are now standards

    • 13 Comments
    OASIS has just announced that version 1.1 of DPWS , WS-Discovery , and SOAP-over-UDP are now officially standards! The links to the RDDL and spec pages currently point to the Committee Specification 1 (CS1) revisions of the specs, but OASIS will update...
  • Dan Driscoll's Blog

    Expirations in WS-Eventing

    • 9 Comments
    WS-Eventing is one of the building-block specifications that DPWS profiles and makes available for solution authors. Some applications require the device to send notification messages back to the client; e.g., a printer sends a message to the PC when...
  • Dan Driscoll's Blog

    Empty Types field in a WS-Discovery Probe

    • 0 Comments
    I've been talking an awful lot lately about WSDAPI, Microsoft's implementation of the Devices Profile for Web Services, but I also work a good deal on the wire side of WSDAPI, and want to talk a little bit about how I interpret an edge case of a WS-Discovery...
  • Dan Driscoll's Blog

    Don't believe me? Just ask Larry.

    • 0 Comments
    QueryInterface isn't a particularly controversial topic (and I haven't heard any grumbling about my last post ) but I always invite you to verify everything I say on your own--partly to ensure that mistakes I make don't make their way too far into the...
  • Dan Driscoll's Blog

    DPWS v1.1 update

    • 0 Comments
    It's been a while since I last provided an update on the standardization of DPWS, WS-Discovery, and SOAP-over-UDP. I'm pleased to say that the standardization committee has produced Committee Specification versions of these three specs--that doesn't mean...
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