At least I wasn't to blame for this death unlike our last chinchilla, who I accidentally stood on as he ran down the stairs. A similar fate befell my brother's cat who ended up under the wheels of his car.
I was worried how our daughter would handle his death, but in fact she was very cool about the situation, mostly concerned about when we'd be getting another pet...
I downloaded and installed IE8 beta 1 primarily to have a look at the new XDomainRequest object which allows for cross-domain requests. Unfortunately that old problem security gets in the way. Although the documentation implies it is possible to make requests to any server, it appears the server has to explicitly support the new request protocol. Ho hum.
Anyway, IE8 screws up lots of pages (most notably Google Maps) and although it claims to have an IE7 emulation mode, using this mode seems to make no difference at all, as far as I can see. So time to uninstall, at least until the next release...
I don't know about you but a lot of my web searches bring up Experts Exchange articles. When you first look at the page, it looks like you have to register to see the responses to the query. In fact it says "All comments and solutions are available to Premium Service Members only". But look a little further down the page (OK a lot further) and you'll see all the responses without paying a thing.
It may seem surprising that the comments are all visible to anybody who hasn't registered, kind of destroying their whole business model. But I guess they have a problem. I'm guessing most of their traffic comes from search engines so they need to have some decent content to get visitors in. To do that, they need to include all the responses. They could hide the text from the browser whilst making it visible to search engines, but this would almost certainly get them removed from the search engine listings, since this would be considered as black hat SEO. So they have to include the responses visible to everybody and just hope they get enough suckers signed up with the huge blocks of text before you get to the real content.
In the first two parts of this series I've given a brief introduction to the integration of Windows Workflow into Metastorm BPM 7.6. For this final part I'll be discussing what interests me, being able to execute workflows authored in Visual Studio from Metastorm BPM.
The first question was, is it even possible? There is no UI for publishing workflows to the Metastorm database, other than those authored in the Metastorm WF Composer. But looking at the database, it looked like the only tables that needed populating were eMSWorkflow and eMSWorkflowDefinition. After some playing around I came up with the following code, a simple command-line tool. This is by no means bulletproof, it will fail if the workflow has already been published (the next version of the FreeFlow Administrator will let you delete workflows) and will likely fail for a host of other reasons. I was using it purely as a proof of concept.
using System;
using System.Data;
using System.Data.Odbc;
using System.Diagnostics;
using System.IO;
using System.Reflection;
using System.Workflow.Activities;
namespace PublishWorkflow
{
class Program
{
static void Main(string[] args)
{
if (args.Length < 4)
{
Console.WriteLine("PublishWorkflow usage:");
Console.WriteLine("PublishWorkflow [ODBC DSN] [ODBC username] [ODBC password] [Workflow DLL] ");
}
else
{
string fileName = args[3];
// get the assembly
Assembly assembly = Assembly.LoadFrom(fileName);
// get the workflow type
Type workflowType = null;
Type[] types = assembly.GetTypes();
for (int i=0; i<types.Length; i++)
{
if (types[i].IsSubclassOf(typeof(SequentialWorkflowActivity)))
{
workflowType = types[i];
}
}
if (workflowType == null)
throw new Exception("Can't find a workflow in the assembly");
string connectionString =
string.Format("UID={0};PWD={1};DSN={2}", args[1], args[2], args[0]);
using (OdbcConnection connection = new OdbcConnection(connectionString))
{
connection.Open();
Guid guid = Guid.NewGuid();
// write to eMSWorkflow
using (OdbcCommand command = connection.CreateCommand())
{
command.CommandText = string.Format(
"INSERT INTO eMSWorkflow (eWorkflowName, eWorkflowGuid) VALUES " +
"('{0}', '{1}')",
workflowType.FullName, guid.ToString());
command.ExecuteNonQuery();
}
// write to eMSWorkflowDefinition
using (OdbcCommand command = connection.CreateCommand())
{
string fileVersion = FileVersionInfo.GetVersionInfo(assembly.Location).FileVersion.ToString();
byte[] buffer;
using (FileStream stream = new FileStream(fileName, FileMode.OpenOrCreate, FileAccess.Read))
{
buffer = new byte[stream.Length];
stream.Read(buffer, 0, Convert.ToInt32(stream.Length));
stream.Close();
}
command.CommandText = string.Format(
"INSERT INTO eMSWorkflowDefinition (eWorkflowGuid, eWorkflowName, eFileVersion, eFullyQualifiedTypeName, " +
"eFullyQualifiedAssemblyName, eWorkflowDefinitionType, eRulesDefinitionName, eLoadedTime, " +
"eWorkflowDefinition, eWorkflowProject) " +
"VALUES ('{0}', '{1}', '{2}', '{3}', '{4}', 'A', '', GETDATE(), ?, NULL)",
guid.ToString(), workflowType.FullName, fileVersion, workflowType.AssemblyQualifiedName,
assembly.FullName);
OdbcParameter parameter = new OdbcParameter();
parameter.Value = buffer;
parameter.DbType = DbType.Binary;
parameter.Direction = ParameterDirection.Input;
command.Parameters.Add(parameter);
command.ExecuteNonQuery();
}
}
}
}
}
}
So I published my simple Visual Studio authored workflow using this code and was able to execute it. It would appear the process context activity provided as part of the Metastorm activities isn't required, although I assume it will be needed if you need to get folder information into your workflow.
The next step was to see if I could execute a workflow that contained custom activities. Obviously the problem here is where will the engine pick up the required assemblies (assuming the custom activities are in their own assembly)? I tried putting the DLL in the engine directory, dotnetbin directory and even the System32 directory (since this is where dllhost lives) but none of them seemed to work. All I got was the following useful error message
Microsoft Workflow evaluation (Instance ID 963fc00a-f2f9-40a8-a0df-7111b0706cd7)
For more information refer to the workflow tracking and event tables.
In fact the tracking and event tables contained no useful information. This error message seems to be the default error message when something goes wrong with a workflow and I've never found any useful information in the database. Debugging the engine through Visual Studio seems to be the only way of getting hold of the real error.
In the end the only way I found to get the engine to pick up my custom activity assembly was to install it in the GAC. Once I did that the workflow executed correctly.
So yes it is possible to execute a VS authored workflow in Metastorm, although some frigging around is required. However I have one concern. One problem I encountered whilst researching this was that workflows would abort after a certain time. Once again, the error above was shown in the Designer Log. Debugging the engine showed the problem was the workflow was timing out. I found a registry setting that controls this timeout, which by default is set to 60 seconds. But how does this timeout work? Is a thread kept alive waiting for the workflow to terminate? If so, this will be a problem for scalability if you wish to execute long running workflows. And that is what Windows Workflow is all about, running some code, sleeping for a week, executing some more code etc. I don't have the answer to this question yet, but will investigate further.
Part 4 - Using your own activities
I've had this for a while, some of the Flash content on the BBC website wouldn't play (although this is better than the problems I had with their previous Real Player content which always seemed to kill my wireless router). I was told my version of Flash wasn't up to date. Re-installing Flash didn't make any difference and following the suggestions here didn't help either.
So I decided to have a closer inspection. I had a hunch it may have something to do with my user agent string, since Flash content worked in some places (including the BBC iPlayer, go figure). So I checked my user agent using the following HTML page
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head> <title>Untitled Page</title> </head> <body onload="javascript:alert(navigator.userAgent)"> </body> </html>
Weirdly this showed my browser as IE6... Which was odd. Searching a bit further I came across this Microsoft article on user agent strings. BTW, the suggestion to type javascript:alert(navigator.userAgent) into the address bar didn't work for me, my guess is this was a security hole waiting for an exploit so has been disabled. Anyway I had a look in my registry to see what was happening and it turned out I had a registry key under HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\User Agent\Post Platform. Part of it pointed to bsalsa.com. I guess I must have installed some of their stuff some time ago though lord knows why they need to fiddle with user agent strings.
Anyway, after deleting this registry key and a restart of IE my user agent string returned to something more sensible and BBC Flash content suddenly sprang into life. Not only that but I can now login into my Fidelity account as well, although that's not necessarily such a good thing given the current state of the stock market.
Update - Hmm, the registry entry has re-appeared, so one of the apps I use quite regularly is writing to that spot in the registry. Next step is to figure out which app it is...
Update 2 - Looks like PHPEdit was responsible, an app written in Delphi which presumably uses one of the components that come from bsalsa.com. I guess any programs using the component may cause the same problem. Getting the latest build from their website fixed the problem.
In part 1 I discussed the new Windows Workflow features in Metastorm BPM 7.6. I'll now move onto the database tables used by WF workflows in Metastorm.
First we have two tables that contain process metadata.
eMSWorkflow is pretty simple, it contains one entry for each workflow published to the database. There is a column for the name of the workflow and a GUID column. The name is the name that will be used when executing a workflow from Metastorm. I'm unclear what the GUID column is for. Multiple workflows with the same name aren't possible so it isn't for differentiating between two workflows with the same name.
eMSWorkflowDefinition holds an entry for each workflow version published to the database. Most of this table is pretty self-explanatory. Again there is a GUID column whose purpose isn't clear. There is an interesting column called 'eWorkflowDefinitionType'. I haven't investigated this too far but it suggests that it is possible to publish workflows as assemblies or as uncompiled XOML file.
Next we have tables that hold workflow instance data.
eMSWorkflowTracking contains audit trail information for executing workflows. It looks like Metastorm have implemented their own tracking service which makes sense since it means the workflow audit trail can be connected to the Metastorm folder's audit trail. One problem I have with the current implementation is there appears to be no way to connect a workflow instance to its type, so it will be difficult to figure out how many instances of a particular workflow type are in existence.
eMSWorkflowEvent also includes data about workflow instances. The difference is that this table contains information that is related to the workflow runtime, rather than the workflow itself. So it will contain entries for when an instance has been loaded or idled etc.
Finally there are two other tables. These are the standard tables created for the WF persistence service, CompletedScope and InstanceState. The Microsoft documentation for these tables seems to be pretty much non-existent, so I don't have much idea what is in there. All I can assume is the 'state' column contains the serialized data of the current state of the workflow instance.
So that's the database tables. Part 3 will discuss running workflows generated in Visual Studio (if I get time to actually get it working).
Part 4 - Using your own activities
