Fixing the WCF - SSIS Web Service Task problem the easy way.

Literally minutes after publishing my post on calling a WCF Web Service from the SSIS Web Service task, I checked back with the forum post that I'd mentioned in that blogpost http://forums.microsoft.com/TechNet/ShowPost.aspx?PostID=1023821&SiteID=17 only to discover that Uwe Heinkel had given me the peice of information I was missing in the first place. So the crux is I don't have to hand craft the dtsx xml file to get it to play ball.

 

I simply remove the following line from the wsdl file

<xsd:import schemaLocation="http://localhost:50344/MyWebService/Service.svc?xsd=xsd2" namespace="http://schemas.datacontract.org/2004/07/"/>

 and it all just works as expected.

 

damn.... I was having soooo much fun wading around in the dtsx xml file.

Calling a WCF Web Service from the SSIS Web Service Task

I have recently been doing some work using SSIS, and this is really the first time I've used for anything serious (ie beyond doing the tutorials that come with SQL Server 2005). I have also recently been learning WCF and as we needed to create some Web Services to deliver the information to SSIS, I decided that this would be the perfect opportunity to put my newly acquired WCF skills to good use. Now I always like to start things out very simply, which in this case meant prototyping the SSIS Web Service Task with the most basic of WCF Web Services I could possibly create, thinking once I get this working, I can then move on to the actual task that I want to achieve with confidence... unfortunately this is where my whole plan started to unravel. For those following at home, here are the steps I took.

1. Create a new WCF Web Service in Visual Studio 2005 by selecting File->New->Web Site, then choosing a WCF Web Service. (Note .Net 3.0 and related Visual Studio extensions are required for this. Also choosing a File based or IIS based web service shouldn't matter).

2. Open the web.config file change the binding to basicHttpBinding (although the same end result is still achieved with the default wsHttpBinding).

3. Expose the metadata over httpget by adding the following line to the service behavior in the config fil

<serviceMetadata httpGetEnabled="true" />

4. run the service.

5. Create a new SSIS project in Visual Studio by selecting File->New->Project, then choosing Business Intelligence->Integration Services from the menu.

6. Add an http connection that points to the wsdl file for your service, and a Web Service Task to the Control Flow that uses the http connection.

7. Edit the Web Service Task, and download the wsdl exposed by your service, and save it locally to a file by using the OverwriteWSDLFile = true on the General page.

8. Select Input, and then select 'MyService' from the drop down.

 

At this point I recieved an error message.

 

Item has already been added. Key in Dictionary: ‘DataContract1’ key being added : ‘DataContract1’

It then would NOT populate the Method DropDown, so I was unable to select a Service Method to call, and because you are confined to selecting from the drop down, there is no possible way to make any of the Web Service method calls.

 

Now I'm the superstitious kind when it comes to writing software, my firm belief is that if you can't get the most basics Web Service working, then you may as well not try to get your complex web service that wants to pass around meaningful data, working, you'll end up in tears.

A google search on the problem yielded the following forum post http://forums.microsoft.com/TechNet/ShowPost.aspx?PostID=1023821&SiteID=17 which was helpful in revealing the underlying problem. The problem is with the generated wsdl and corresponding schemas, not sure exactly what is wrong with them, but for some reason, the UI in Visual Studio doesn't like the way WCF publishes its metadata, in particular the way it published metadata about its DataContracts (complex types). So I thought I'd make the default WebService that WCF generates even simpler by removing any trace of the DataContract. This worked fine, I could call a WCF WebService from within SSIS no problems... with the restriction that I could only pass primitive types to/from the web service. now this might be fine for your purposes, but I required something a little more powerful, so I decided to persist with figuring out the solution.

 

I tried a number of things with the generated schemas, but I think in the end I'd exhausted my limited understanding of wsdl and xsd, and was no further ahead. Next I remembered a very simple statement by a fellow collegue of mine Andrew Ball who was at the time giving me some SSIS advice. He said "... under the hood an SSIS package (dtsx file) is just a big xml file". Armed with this I began to see the issue as more of a tooling issue, and thought that maybe the issue is purely with the designer. So I cracked open a sample that Andrew had sent me and found where the various Web Service properties were being set. I also cracked open good old reflector and took a look at the way in which Complex Types were handled in the Microsoft.SqlServer.WebServiceTask.dll Which is responsible for the Web Service Task in SSIS. about half an hour later (give or take 10 mins) I had the following XML

<WSTask:MethodInfo WSTask:MethodName="MyOperation2" WSTask:MessageName="">

<WSTask:Documentation>

Basic Hello world service call that uses a DataContract

</WSTask:Documentation>

<WSTask:ParamInfo WSTask:Name="dataContractValue" WSTask:Datatype="DataContract1" WSTask:ParamType="Complex" WSTask:SeqNumber="0">

<WSTask:ComplexValue>

<WSTask:ComplexProperty WSTask:Name="FirstName" WSTask:Datatype="string" WSTask:ParamType="Primitive">

<WSTask:PrimitiveValue>Scott</WSTask:PrimitiveValue>

</WSTask:ComplexProperty WSTask:Name>

<WSTask:ComplexProperty WSTask:Name="LastName" WSTask:Datatype="string" WSTask:ParamType="Primitive">

<WSTask:PrimitiveValue>Baldwin</WSTask:PrimitiveValue>

</WSTask:ComplexProperty WSTask:Name>

</WSTask:ComplexValue>

</WSTask:ParamInfo>

 

Which when placed inside a web service task element, can be used to successfully call the web service with the DataContract.

 

So my conclusion is that there is a bug in the SSIS Web Service task UI that doesn't handle populatinf the Method drop down correctly (I'd trust WCF before I'd trust SSIS), but this is merely a bug with the UI, not with the way in which the Web Service task actually goes about calling the web service.

 

 

Added after post (literally minutes after): For the easy way to solve this problem see http://sjbdeveloper.blogspot.com/2007/03/fixing-wcf-ssis-web-service-task.html

Flickr becomes alive

Just found a really neat Plugin for Windows live writer called flickr4writer that allows you to add images from your Flickr photos by simply clicking "Insert->Flickr image...", so to celebrate here is one of my flickr photos.

 

Molly helps Microsoft with Standards

This is huge... I've been up against some major deadlines so I haven't been keeping up with all my blog reading, but today I decided that before I go home I was just going to catch up on a few of the more important ones, and so I was reading the IEBlog when I stubled across this article, the basic crux of which is that Molly E. Holzschlag has "signed on with the Internet Explorer team on a contract basis to work on standards and interoperability issues".

 

I have actually heard Molly speak at the Web Directions South conference last year, and she is a really inspiring speaker, and someone who tirelessly advocates for better adoption of Web Standards. It'll be interesting to follow her progress at The Daily Molly.

Published articles for The Readify Tech news letter

Just thought I'd mention that I now have a published two part article on the Readify tech news letter on SQL Server Express Edition.

 

You can view the articles at

SQL Server Express (Part One) - Another reason to move your user applications onto a stable platform

and

SQL Server Express (Part Two) - How User Instances Work

It finally dawned on me why I don't like the name "ASP.Net AJAX"

Microsoft renamed their AJAX offering from ATLAS to ASP.Net Ajax around November last year. Now I personally never quite understood what was so bad about ATLAS, but I do realize that as a general rule, product code names generally have to change at some point before the release to the main stream, (Longhorn -> Vista, etc...), but I must confess that quite often Microsoft completely screw it up.

 

I guess there is significant pressure from various departments, notably marketing and branding who want to maintain a consistent theme, and have the morbid fascination with trying to imbibe descriptive meaning into product names, and also from the legal department who are desperately trying to avoid trademark infringements. This is why I didn't blog about the name change when I first learned of it, but I always felt a huge sense of disappointment about the change, but couldn't quite put my finger on why I was so disappointed... until this week.

 

Beyond the obvious lack of imagination displayed taking the two core technologies (ASP.Net and AJAX), and just combining them (which in itself causes some confusion), I realised something this week when I was attempting to debug an issue with the library. As a developer one of our most important tools is our favourite Internet search engine. Whenever we come across a problem say with a CSS styling that isn't displaying correctly in a browser we just go to our favourite search engine and type in a question, for example "CSS min-width Internet Explorer". In Google the first page of the previous search returns all types of useful hits, including information regarding the fact that min-width is not supported in Internet Explorer 6.0 and a number of ways you can work around this. This is very powerful and allows us to do our jobs a lot quicker.

 

I discovered when trying to debug a problem with ASP.Net AJAX that this using ASP.Net and AJAX is not only longer to type than ATLAS, but returns all kinds of results that you wouldn't really be interested in. If you just type in ASP.Net AJAX into Google, the first page returns (as you'd expect), the official home page (ajax.asp.net), and a few other relevant topics, but then it starts to get more off-topic, like other component vendors offering AJAX style controls in ASP.Net such as ajaxium, ajaxpro, etc..., this is then further confounded if you need more search terms. The search is helped marginally by quoting "ASP.Net AJAX", but still returns that ajaxium website in the first page of results.

 

If Microsoft had've done what the trend is in the rest of the industry and actually used some imagination to come up with a short sharp name that was unique in the industry space, it could've made all our lives a little bit easier.

Dell Quickset disabling Internal network card

I had an interesting network problem today. I arrived at work, plugged my laptop into the power, and then into the network cable, switched it on only to find that I had no network connectivity. After rebooting twice, and discussing it with my colleague sitting next to me who has pretty much an identical laptop, connected to the same router, with no such networking problems, I did a bit of poking around.

I have a latitude D820 running Windows Vista, and the Dell Quickset power utility. One feature of quickset is that it disables the internal network card if you are not using it and you are on battery power, to get a few more minutes of battery life. It turns out that it must be a bit buggy as this turned out to be my problem. It had disabled my network card from the night before, and admittedly I had suspended my session, but then this morning, even after plugging into the power at work, and after rebooting my system twice, my network card still failed to respond. I fixed it by explicitly setting in the quickset UI to "always activate on battery".

IE Developer toolbar rocks

Just downloaded the latest beta of the IE Developer toolbar, and I must say it seriously rocks....

 

I've been using previous versions for a while now, and have found it extremely helpful in debugging styling problems, but this version goes to the next level. I haven't had a good chance to put it through it's paces yet, but I'm sure the "Style Trace" functionality will prove indispensable. It'll be interesting to see what will be in the final version of this product, they may even start to challenge firefox as the "Developers preferred browser", although I think they still have a way to go there.

Web Directions North gets the nod of approval from Microsoft Luminaries

Just read a post on PeterL's blog, about Web Directions North. I went to the Web Directions South conference myself. Here's my wrap up of the Aussie version, although I must admit that my post doesn't do it justice, the event is well worth attending, and will challenge the way you think about the web.

 

Warning: if you do anything of note during a session, you'll probably see yourself used as an example of the power of web 2.0 as the speaker pulls down the flickr image of you minutes after the event.

 

tags: wd06

Back and Live

After much frustration with Windows Live Writer (Beta) and Blogger (Beta) having communications issues, I am now back blogging with Windows Live Writer.

 

Gotta love trying to get two beta products communicating.

 

 

Technorati tags: blogger, Windows Live

As Kermit would say ... "It's not easy being Green"

A fellow collegue of mine Darren Neimke has posted a rather interesting post on his blog, which has got me thinking. Now I have to admit, I do consider myself to be a "Greenie", however, far from having "jumped on the bandwagon, I have been a member of The Australian Greens now for well over 3 years, and in fact I can trace my pilgramage from the high slopes of comfortable numbness about environmental issues into the radical valley of the shadow of Greenie Activism to a course I took back at uni, almost 11 years ago. A philosophy course aimed at Engineers called Technology and Human Values in which we studied "systems engineering" approaches to the ways technologies are used and abused both here and in developing countries.

Anyway, my main reason for writing this blog article is to suggest to Darren, that I feel has has understated some of the issues slightly. I am ussuming that some of the understatements were intentional and for effect like " .... Or some ice melting in Antarctica." trivialising the disapearance of entire glaciers, however, I the one I really want to concerntrate on is the issue of research and the problems of people reading something and just believing it. From his post

Research is a skill that is being diminished by the one-click world of Google and the new media. People hear something and believe it to be true without even having the faintest clue of how they would ratify such assertions.

I think in this statement are a number of problems all rolled into one.
Firstly, yes we live in a society based on instant gratification. Google is a great tool, that can be used to justify any point of view you want to throw at it.
Secondly, I think it is quite difficult to "ratify" certain facts. The problem comes from the nature of the beast that is science. To really fully understand the latest scientific findings, requires you to pretty much be at the forefront of scientific reseach in that particular area, and this requires not only having a PHD, but being actively involved in hands on research. The problem is that even scientists at this level can't always seem to agree, and the way in which research projects get funding often requires researchers to make bold (sometimes even rediculous) statements to gain the attention of the various institutions that are willing to put up the money to fund this research. How is your average punter expected to be able to know what the truth is even if they have tracked down the information from people considered leaders in their field.

Not wanting to be all doom and gloom, I think that there are solutions emerging to these problems.

If I may use a buzz-word, with the web 2.0 paradigm, we are starting to understand the "wisdom of the crowd", in fact google has used this in its search algorithms for a while, but there are even more powerful tools that enable collaboration on an unprecidented scale, sites such as wikipedia are classic examples of this.

With respects to the scientific community, by its very nature, it is a dynamic exchange of ideas and theories. unlike other debates we encounter, such as religion, politics etc... there are not the same intitutionalised barriers to callenging the status quo. If a scientist or group of scientists have a theory, this will be critiqued by many other scientists who will then be able to repeat either the same experiment and validate the findings, or disprove them. Even if a scientist or group of scientist start to hold some political sway, and spread inaccurate theories for a time, eventually someone will be able to challenge the theory, and a better theory will prevail.

So where does that leave us with the environment debate. Well, my personal feeling is that the premise that us 6 billion humans are having a noticable impact on the world we live in has been kicking around for long enough now, and the vast majority of scientists who are working in the field seem to agree on some of the big ticket items that constitute climate change. What the results might be are admitedly speculation. Educated speculation, but speculation none the less. However, I think that we can no longer use the ignorance is bliss approach to keeping the status quo. We have to realise that systematic change is essential if we as a species want to continue to maintain the quality of life that we currently do. Even more so if we want to take any significant amount of non-human species into future. This then becomes a battle that sometimes needs to be fought on a political level, and sometimes on a personal level. So Darren, next time I'm bending your ear about how stupid it is to be logging our water catchments for wood chips in the middle of a drought, and you slip seemlessly into that glazed over look, at least you'll know where I'm comming from.

Technorati and claiming your blog

I started playing around with Technorati the other day and decided to "Claim my blogs", just to see if anyone else was linking to me. I have two blogs, this one which is my geek blog, and another one that I reserve for my thoughts on politics/art/etc... anything that's not technology related. To my surprise I found quite a few people link to this blog, but to mt disappointment, found that I had absolutely NO links to my other blog. I guess that's no surprise really considering I have never been really active in promoting my other blog. So I thought I'd actually attempt to add some technorati goodness by putting in a shameless plug on my popular blog for my less popular blog.

Musings of a Morbid Mind.

No prizes for guessing that aliteration is one of my favourite literary devices.

Development V's Production Environment

An interesting post on software environmental issues by Mitch Denny caught my attention today, not only because he sent a link around on our internal tech list, but because it's something that I think continually trips up a lot of developers (myself included). Mitch basically argues (and I agree) that development should be done in the same basic environment as the production system, he plays this off against infrastructure people who tend to want to keep a gap between production and development for safety reasons, I mean wo knows what wholes these crazy developers are going to poke in our top-notch security infrastructure.

Most of my experience has been in the shrink wrapped software industry ans as such, there is little point trying to match development and production environments, so in this case I suggest develop on the environment that makes the developers most productive, but then make sure you test, using whatever virtualisation technology you prefer, on ALL platforms in your supported platform matrix.

With enterprise development however, I would say that one should develop in an environment as close as is practicable to the production environment. It never ceases to amaze me the amount of problems that arise because of differences between the development and production environments. Have you ever heard a developer say "gee, it doesn't do that on my machine". The closer you make development environments to the production environment, the less you'll hear this anoying phrase.

The flip side of the coin is that developers need to understand fairly well the differences between their development environment and their production environment. One thing that has bitten me in the past, and a lot of other developers as well is the difference between IIS and the Visual Studio Development Web Server (The web server formerly known as Cassini). There are a number of differneces, and also a number of reasons that developers like to use it over IIS. One major difference which always seems to trip me up is that Cassini passes every requested file through the ASP.Net pipeline, as opposed to IIS which will serve a lot of files normally (ie *.css, *.jpg, *.gif, *.png, *.html, etc...), and only pass the ASP.Net specific files (*.aspx, *.asmx, *.ashx etc...) through to the ASP.Net pipeline. When you first start a project you don't really notice any difference until you think to yourself, "gee, it would be nice to add forms authentication now", and so you put in the standard <deny user="?" /> element and all of a sudden your login page has no graphics and doesn't look anything like how you designed it. This is because Cassini is sending all of you image and css files through the ASP.Net pipeline and they are getting blocked by the Security module because you are not authenticated... yet.

Tags: ASP.Net, IIS

Visual Studio 2005 misbehaving after Automatic updates

I have spent the morning struggling with Visual Studio. It has been crashing non-stop, but I have got to the bottom of the problem, and am happy to share with the rest of the world.

Visual Studio was happily starting and loading my solution, but whenever I clicked on the test menu and attempted to do something like open the TestView window, VS was crashing. If I tried to open a localtestrun.testrunconfig file it would crash with the following error "Could not open assembly System.Data version 2.0.0.0 .... The system cannot find specified path".

I won't bore you with the process I had to go through to find the resolution, but the problem turned out to be that this morning My machine installed some updates from Windows Automatic Updates. Most of these updates were succesful, but one of them, namely "Security Update for Microsoft .NET Framework, Version 2.0 (KB922770)" had failed with the following error "Error Code: 0x643". after doing a search on this particular error I found the following article http://support.microsoft.com/kb/923100. However, I did not need to follow the resolution outlined there, I simply went to the Windows Update site and manually installed the update.

I hope this helps someone out before they have to spend half a day like I did trying to track it down.

PopupControlExtender inside an EditTemplate

I found a problem today with the PopupControlExtender (Part of the ATLAS Control ToolKit), that occurs when it is embedded inside an EditTemplate for a GridView Control. I suspect the same problem would occur inside any template field, and potentially for other ATLAS Control Toolkit controls.

I wanted to edit a date field inside my EditTemplate, and so I set about implementing something not too dissimlar to the example for the PopupControlExtender on the Atlas Control Toolkit website. Firstly I prototyped it on a page all on its own, no problems everything worked as expected. Then I attempted to place the same code inside my EditTemplate field. At this point when I attempted to go into edit mode I recieved an error message "Assertion Failed unrecognized tag atlascontroltoolkit:popupControlBehavior". Obviously the necessary javascript libraries were not being downloaded when the page rendered. I assumed this was because of the dynamic way in which the EditTemplate renders.

To fix this problem, I simply placed an empty PopupControlExtender onto the design surface of my page. This ensures the necessary javascript files are downloaded, and when the EditTemplate is rendered, the ATLAS engine knows what you're talking about.

I also encountered a coulpe of bugs with the popup control being wrapped inside an update panel. I managed to fix these by simply downloading the latest CTP of the ATLAS Control Toolkit, (now called the "Microsoft ASP.Net Ajax Toolkit"... sorry guys, this is yet another example of how insisting on meaningful naming of products can really kill any excitement and mistique around it, I'm afraid it just doesn't have the same panache as "Ruby On Rails", and if you really want to speak to the buzzword concsious managers of today, you have to break away from boring naming conventions and inject some creativity into the process).

tags: ASP.Net, AJAX

Reflections on Web Directions

I have to be the slowest blogger in the IT community. Over a week ago I attended the Web Directions conference. The conference was really good, and has inspired me in a few areas. Many other bloggers have had their say on the conference, but I may as well have mine, just for the sake of redundancy.

One of the common themes from both the Accessibility speakers (Gian Sampson-Wild and Derek Featherstone) and the User Experience speaker (Kelly Goto) was user testing, and not just asking the user what they think. Kelly Goto's quote was 'We listen to what the users "didn't say" and observed what they did'. I have also been challenged in the area of accessibility, I think the quote for me came from Derek Featherstone, and that is "The web is Accessible by default, we make it in-accessible". It has inspired me to go have a look at the way I develop, and the bad habits I've gotten into. The truth of the matter is that it is not really that much effort to get into good habbits that make web sites more accessible.

I really liked Jeremy Keith's AJAX sessions. The first session started out a little basic, but become more interesting in the last half. In the second session Jeremy discussed a technique he called "Hijax" which is aimed at ensuring accessibility, and support for down level browsers. I am looking forward to seeing how well I can apply his techniques using ATLAS. While on the topic of libraries, Jeremy did make one statement that I'm not sure I can agree with. He said that he didn't believe in using thrid party libraries for doing AJAX, firstly becasue AJAX wasn't that complicated and secondly because if something goes wrong in the library as a developer you'll need to be able to fix it. I almost agree with his first statement, but even still, I am a big fan in NOT re-inventing the wheel. If there's a library that has a great ranking control for example, and they've coded it so that it works across all browsers in your supported browser matrix, then there is a lot of testing and coding that you can potentially avoid. There are always bugs in any software, and AJAX APIs are no exception, the skill of a good developer is to be able to use an API in such a way that they can workaround any bugs in the underlying API, I've lost count how many times I've had to do this myself. Also, as a Winforms developer, I am extremely greatful that I do not have to write Win32 anymore, and I'm sure those of you who have written Win32 would agree with me. Having said that, his "hijax" mechanism of progressive enhancement is really cool, and my current goal is to go through all the ATLAS controls (the API I'm currently using) and see how I can apply this technique to them.

I went along to John Allsops talk on microformats to hopefully pickup anything I'd missed from the first time I heard it, and was inspired all over again.

One minor thing I think the organisors can improve on is something I saw at the Tech-ed conference, the "re-charge desks". The tech-ed organisors had desks with a series of power boards that people could plug their lap tops into between sessions. This would have been really good for me as my laptop is now a year and a half old, and my battery is showing its age, it wasn't even lasting 2 hours.

Worth mentioning:

• Kelly Goto made reference to an example of an interesting User Experience project called Datelens. It is a callendaring visualisation which plugs into outlook (nothing to do with the web at all). I downloaded it and it's quite interesting, definately worth a look. Also it is written in .Net 1.1, which must have been quite an acheivement, and I think with WPF just around the corner, there will be a lot more of these types of user experience applications about.
• The inaugural McFarlane proze for Excellence in standards based web design was awarded to http://www.museum.vic.gov.au/caughtandcoloured/. This site is really worth checking out. It is especially interesting to me because it is written in ASP.Net demonstrating that it is possible to write high quality standards compliant accessible web sites using ASP.Net.

• - The last speaker of the conference was Mark Pesce (inventor of VRML, explained some of his concepts of social software, and described a project he worked on that attempted to aggregate your social behavior patterns and create social network models simply by using the ability of a blue tooth enabled phone. I thought there’d be some people at readify quite interested in this sort of stuff. http://relationalspace.org/

tags: wd06

ATLAS Data Applications and Down-level support

I must confess that aslthough I am excited by the whole AJAX phenonenon, and the rich client experience that it provides for the majority of desktop browsers, I sometimes feel concerned about those that for whatever reason aren't able to experience the full beauty of a javascript enabled client. There are two main groups of people that are missing out

1. Users with certain accessibility needs (often browsers and tools designed for people with disabilities have to run without the javascript support we usually take for granted) and
2. PDA users (This is an increasing market, and to date only 1 browser has implemented any kind of javascript engine for devices, Opera.

So I am always looking for ways to enhance these users experience.

My AJAX toolkit of choice (more through accident than intent) is ATLAS (Microsofts library). ATLAS contains a data enabled control called a ListView which is quite powerful. It works on a client side JavaScript based object model and the best way to get to know it is to read the data section of the ATAS documentation.

 

So the idea is, get a funky ATLAS based website working, and then attempt to create a version of that website as quickly as possible that can be used by people who can't (or won't) use javascript (similar to what google does with gmail).

 

I decided to make the sample as simple as possible without loosing anything along the way. I decided to create a Shopping List, that simply contains a quantity (double) and an item (string).

The bueaty of the ListView in ATLAS is that it can use the System.Component model similar to other databinding in ASP.Net 2.0. So the first step in creating a webservice that derives from Microsoft.Web.DataService (refer to the ATLAS documentation for more details).  I then create my ListView templates and hook it all up using XML-Script, and pretty it upwith any CSS I may care to add. The result can be seen here (Please forgive me I'm not a graphic artist). Once this is done, I needed to create a Non-ATLAS version of the same page. As my webservice already uses the System.Component model, it was extremely easly to add a GridView control, select an Object DataSource and wire it up, and away it goes. All in all it took me abou 10 minutes to create the NON-Atlas page. It would have taken me another 2 minutes to enable things like edit/delete, but for the moment I wanted to keep it the same as the ATLAS version, this may be the subject of a future post. The only significant difference between the two pages is the presence of a select link on the NON-ATLAS enabled version whereas the ATLAS version manages the select operation simply by handling the mouse click.

 

Once you have these two pages it is simply a matter of choosing your favourite way to direct users with different broswser capabilities to the correct site.

ajax gotcha for new players

Being fairly new to the "Brave New World" of ajax, this week I fell into a fairly common trap that gets new players. I studiously looked around for the best practice implementation of making an http request using javascript and came up with the following javascript function which allows the user to make the http request, specify a callback function, and even goes the extra mile of implimenting timeouts (I guess the only other thing I really should do is implement an OnErrorCallback).

function MakeRequest(url, timeout, 
    onCompleteCallback, onTimeoutCallback)
{
    var completeCallback = onCompleteCallback;
    var timeoutCallback = onTimeoutCallback;        
         
    var xmlHttp=createXMLHttpRequest(); 
    
    if (xmlHttp)
    {          
        xmlHttp.onreadystatechange = function()
        {                
            if (xmlHttp.readyState == 4)
            {            
                window.clearTimeout(timeoutId);
                if (xmlHttp.status == 200 || 
                    xmlHttp.status == 304)
                {                
                    completeCallback(
                        xmlHttp.responseText);
                }
            }
        };
                                 
        xmlHttp.open("GET",url,true);
        
        var timeoutId = 
            window.setTimeout(function()
        {        
            if (callInProgress(xmlHttp))
            {
                xmlHttp.abort();
                timeoutCallback('timeout');
            }
        }         , timeout);
        
        xmlHttp.send(null);        
    }
}

function callInProgress(xmlHttp) 
{
    switch ( xmlHttp.readyState ) 
    {
        case 1, 2, 3:
        return true;
        break;

        // Case 4 and 0
        default:
        return false;
        break;
    }
}


function createXMLHttpRequest() {
  if(window.XMLHttpRequest) {
    try { 
      xmlHttpRequest = new XMLHttpRequest();
    } catch(e) { return null; }
  } else if(window.ActiveXObject) {
    try {
      xmlHttpRequest = 
        new ActiveXObject("Msxml2.XMLHTTP");
    } catch(e) {
      try {
        xmlHttpRequest = 
          new ActiveXObject("Microsoft.XMLHTTP");
      } catch (e) { return null; }
    }
  } else return null;
  return xmlHttpRequest;
}

I then wanted to call a .Net HttpHandler, and lets just say for arguments sake that the htp handler looks like this

public class Handler : IHttpHandler
{
    
    public void ProcessRequest (HttpContext context) 
    {
        System.Threading.Thread.Sleep(6000);
        context.Response.ContentType = "text/plain";
        context.Response.Write(Guid.NewGuid().ToString());
    }
 
    public bool IsReusable 
    {
        get 
        {
            return false;
        }
    }       
}

so the call from javascript would simply look something like this

        MakeRequest(
            'Handler.ashx?cookie=abcd&another=xyz', 
            20000, onRequestComplete, 
            onRequestTimeout);       
        
        function onRequestTimeout(response)
        {
            alert('timeout');
        }
        
        function onRequestComplete(response)
        {
            alert(response);
        }

The problem as I found out through good old wikipedia relates to the internet explorers caching of the "GET" http command as described in this article on HMLHttpRequest.
As discussed in the article, there are a number of ways around this, switch to using POST or ensure that you switch the caching off in the http headers. I chose the former.

Automatic updates + Automatic Reboots

Is it only me or does anyone else find this really frustrating.



I got this in the middle of reading my email this morning, and I really didn't want to reboot in 5 minutes. I would have quite hapoily rebooted in half an hour or so when I'd finished what I was doing. The fact that the restart later button was there but disabled just added to the insult.

I think from a layer 8 perspective, Microsoft need to be really careful when forcing reboots. If this happens too frequently, it may be frustrating enough that people actually turn Automatic Updates off, making their systems progressively less secure and vulnerable.

Web Directions

On thursday night I went along to a Web Directions preview night where 2 of the speakers from the upcomming Web Directions conference Ben Barren from gnoos and John Allsop from westciv were giving previews of their presentatoins at the conference. It was a good night, I particularly enjoyed Johns talk on microformats. This is a topic that I have been interested in for a while now, and may have more to say about it later.

Unlike other events I attend, where I know a fair few people, this event I only found one person I'd met before was Nigel Watson, an Architect Advisor from Microsoft. So it was good to make new contacts and expand my circle beyond the sphere of the Melbourne .Net developer and SQL Server sphere. I got to meet Cameron Adams whose book "The Javascript Anthology" I am currently half way through, and also met the people from westciv who write the best damn web standards online training courses in existance.

When I first heard about the web directions conference, I thought that as much as I'd love to go along, I probably wouldn't be able to attend given that I was already attending Tech Ed at the end of August, and I'd be pushing it a little if I asked my employer to pay for another conference and let me have the time off so close after Tech Ed. As the saying goes, "the best layed plans of mice and men gang aft aglay", there was a lucky door prize drawn at the end of the night, which was a free ticket to attend the Web Directions conference. Guess who won........ So now all I have to do is convince my employer to let me have a couple of days off to attend..... that shouldn't be too hard.