Paul Fallon's WebLog

Blog moved....

no1138 — Sat, 26 Feb 2005 03:34:00 GMT

My Blog is now at http://paulfallon.com

Omri Gazitt talks about what Microsoft is doing with Web Services

no1138 — Tue, 11 Jan 2005 00:29:00 GMT

Omri Gazitt is the product unit manager on the advanced Web Services team.

The folks at Channel9 ask him, What is Microsoft doing with Web Services?

you can see the video at http://channel9.msdn.com/ShowPost.aspx?PostID=34980#34980

Ciao,

Volatile Transactions & In-Memory Transactions - do they have ACID, ACId or ACI properties?

no1138 — Mon, 13 Dec 2004 01:07:00 GMT

In my last blog posting, How should we think of Transactions ? I mentioned Volatile transactions and how I currently think they can be perceived in different ways! Do they have ACID, ACId or ACI properties?

In case you do not know what Volatile Transactions (aka In-Memory Transactions) are, they are transactions that do not persist to a durable store such as a hard disk (ouch! we have multiple definitions of durable to content with ). They are transactions that are done completely in memory and do not incur the I/O cost of writing to a hard disk a Transaction log or the actual known data/state.

What is interesting about Volatile transactions is that they are sometimes perceived as not being Transactional, because they are viewed as not meeting the ACID properties, especially the "D" property. I suspect the main reason for this view is because there are no Transaction logs and/or no data stored to hard disk.

So when you look at a typical definition of the ACID properties (like what I have listed below), some of the reasons why this view maybe held become apparent:

(NB. this is an amalgamation/synopsis of many definitions I have seen)

A - Atomicity - Transactions are atomic (all or nothing)

C - Consistency - The transaction is a correct transformation of state. Consistency constraints that are defined on the underlying data servers are preserved by a transaction.

I - Isolation - Each transaction should appear to execute independently of other transactions that may be executing concurrently in the same environment.

D - Durability - Once a transaction commits, it’s updates survive even, if the system goes down

ok, so a Volatile Transaction meets the ACI of the ACID properties, but not the D as defined above. But is this ("Once a transaction commits, it’s updates survive even, if the system goes down") a true reflection of what Durability means? Many similar variants of this definition gets used on a frequent based and they bring specifics to the definiton that are not about the failure of meeting the ACI properties or making the "Commited" value available/public but focus on the failure of media or a system. In my opinion the failure of media or a system is not an aspect of the paradigm or indeed part of the ACID properties, but an aspect of how the paradigm can be implemented and/or a requirement of the longevity of the state being persisted/determined. It is perhaps the fact that the best known implementation of the data server feature of the transactional paradigm is a database that has led us to shape the ACID properties to the specifics of databases. But perhaps the Transactional paradigm has more to offer than the correctness of data/state transformations on a database. The transaction paradigm has a core focus on simpilifing how we can achieve the correctness of data/state transformations where we may have to deal with concurrency management and recovery control and this can be applied to any transformation of state.

Perhaps a different way to look at the durability of ACID is where the definition of ACID as an acronym came from and how some of the leading experts in the industry define them. As far as I know the ACID acronym was first coined by Haerder and Reuter (1983). The definition I like to use is that by Gray and Reuter (1993). It is the following:

A - Atomicity - A transaction's changes to state are atomic: either all happens or none happen. These changes include database changes, messages, and all actions on transducers.

C - Consistency - A transaction is a correct transformation of the state. The actions taken as a group do not violate any of the integrity constraints associated with the state. This requires that the transaction be a correct program.

I - Isolation - Even though transactions execute concurrently, it appears to each transaction, T, that others executed either before T or after T, but not both

D - Durability - Once a transaction completes successfully (commits), its changes to the state survive failures.

When you read this definition of Durability (and the ACID properties overall), it in my option explains the feature richness of transactions and how it can be applied to the persistence of the transformation of state and also how it applies to the other properties such as A, C and I. The state survives failures by the data server ensuring that when the transaction commits a new durable state is persisted/stable/available/public and if something goes wrong (such as not be able to ensure Consistency) that the data server returns to the previous known state. In essence, this is a contract that guarantees the persistence and stability of the state and that the outcome of a transaction is known/public and usable in subsequent transactions, as a known/correct state. A good definition I have seen is that once a transaction is committed, it cannot be abrogated.

With Durability being about the persistence, stability and making public of “commited”/known state as we transform from one known/correct state to another, it allows us to leverage the transaction paradigm in many scenarios. For example when using Volatile Transactions, we are leveraging data servers that store data on Volatile media, such as RAM and providing the transaction paradigm in-memory. With the common misunderstanding that Transactions are exclusively for databases, the question arises about the “D” property.

For me the Durability aspect of a transaction is present in a Volatile transaction. The question is whether its “D” or “d”. Since most transactions are based on the X/Open Transaction processing model, the requirement for log managers or lock managers in resource managers (data servers) are not central or core to implementing the transactional paradigm at a base level. In relation to the usage of Volatile media for Transactions? in my opinion the requirement of the media used by the data server is that it is able to present a stable/persistent/public state once "Commit" has occured. So I believe that Volatile Transactions meet all of the ACID properties and that its ACID with a "D"

phew! long post.

I guess the crux of the issue is the 2 uses of "durable" when talking about Transactions. One is the "D" in the ACID properties and the other is the property of the data/state/media being used (and how it is stored). The "D" in the ACID properties is more about making a "commited" value available and the other is about an implementation requirement of how long (and/or resilient) a known/committed state must be.

PDC 2005 - are you going to be there? Los Angelas - Sept. 11 - 16, 2005

no1138 — Mon, 13 Dec 2004 00:04:00 GMT

So now the news is out, there is going to be a PDC 2005

There are currently no more details available, but you can signup for updates as the details develop.

64-bit .NET Framework programming section on MSDN goes live!

no1138 — Thu, 02 Dec 2004 03:48:00 GMT

A new section of the .NET Framework Developer Center went live today, it focuses on 64-bit .NET Framework programming.

Over to Frank Redmond for the details:

Check out the MSDN .NET Framework Developer Center’s new 64-bit .NET Framework programming section! The new 64-bit .NET Framework programming section includes: development articles, tools and community resources as well as 2 step-by-step Hands-On Lab (HOL) samples that will get you up to speed quickly on 64-bit .NET Framework programming. HOL501 addresses the most common managed code migration scenarios: migrating managed code with no native dependencies, migrating managed code w/a dependency on a native DLL, migrating managed code w/a dependency on a native DLL that requires unsafe code and migrating managed code w/a dependency on a native COM component. HOL503 addresses C++ migration issues such as data type changes to the Win32 API and floating-point differences as well as investigating memory performance considerations. The new 64-bit .NET Framework programming section also includes a step-by-step guide on Visual Studio 2005 remote debugging. Check out the new 64-bit .NET Framework programming section on the MSDN .NET Framework Developer Center and let me know what you think!

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Windows 64-bit Hands-On Training & Windows 64-bit Compatibility Workshops

no1138 — Fri, 19 Nov 2004 01:57:00 GMT

From Jan till July of next year, the Route64 Training Tour is visiting over 20 cities providing:

Windows 64-bit Hands-On Training is a 3-day training designed to provide the most comprehensive contents of of what it takes to fully leverage Windows on 64-bit processors. At the completion of this training, we expect attendees to be fully comfortable with developing on Windows 64-bit and in some cases to have fully ported their application. This training includes two tracks, the Server and Client Tracks. Read more about the tracks.
Windows 64-bit Compatibility Workshop is a one-day training for ISVs and Enterprise developers who are looking at testing their 32-bit application on a Windows 64-bit. The workshop includes several hands-on sessions on three architectures to give you the opportunity to experiment with Windows 64-bit.
Windows 64-bit Device Driver Workshop is a one-day training for IHVs and Enterprise developers who wants to start porting their 32-bit device driver on Windows 64-bit. This workshop is designed to present the key differences between a 32-bit environment and a 64-bit one. It includes several hands-on sessions on porting Device Drivers. Because of the complexity of running a Device Driver workshop, this workshop runs only in some selected cities.

So if you are looking to learn more about:

Windows 64-bit & Hardware Architectures
Migrating C/C++ Applications to Windows 64-bit
Optimizing SQL Server on 64-bit
OpenGL in a 64-bit environment
COM Components in Windows 64-bit
.NET Managed Code in Windows 64-bit

as well have opportunities on three different configuration of Windows 64-bit:

You can find more details and how to register at the Route64 site (http://www.route64.net/)

On Demand 64bit Windows Webcasts

no1138 — Fri, 19 Nov 2004 01:45:00 GMT

At http://www.microsoft.com/seminar/events/series/msdn64bitwin.mspx you will find a series of Webcasts that focus on 64bit computing on Windows.

Tune in to this webcast series and learn of the advantages that 64-bit computing brings:

Run existing 32-bit code without modification on 64-bit Windows.
Write native 64-bit code (managed and unmanaged)
Learn about the next generation of development tools.
Find out about 64-bit processor architectures.

MSDN Ireland at the Movies: Dr Strangelove

no1138 — Tue, 02 Nov 2004 21:19:00 GMT

   Dublin - Monday 15th November, Sugar Club, Leeson St, Dublin 2, 7pm.
   Belfast - Tuesday 23rd November, The Vue Cinema, Odyssey Pavillion, 7pm.
   Galway - Wednesday 24th November, Cinemobile, The Huntsman Bar, 7pm.
   Cork - Thursday 25th November,Triskel Arts Centre, 7pm.

Developers.ie is live

no1138 — Tue, 02 Nov 2004 21:18:00 GMT

Pascal and the Irish Developers Alliance members have been busy. The site is live and you can find forums and blogs for Irish developers. Nice one folks!

Eric Rudder is speaking at our next MSDN event, WOW!!

no1138 — Wed, 20 Oct 2004 06:20:00 GMT

Congratulations to our local DPE in Ireland, they really have out done themselves this time!! On Wed. the 3rd of Nov, we have a full day event that is jam packed with great sessions and exceptional speakers. The list of speakers includes Eric Rudder, who is the senior vice president of Servers and Tools. Eric and his team are responsible for everything that is the programming model for the client and server, for creating the best tools for the .NET platform and for fostering synergies between Windows and the Windows Server System offerings. IMHO, I think one of the best descriptions of his role is on BusinessWeek.Com, he is the .NET General.

IMHO this is a must for every Irish developer as Eric is going to cover the Future Landscape of Microsoft's Servers and Tools and boy!! do we have some really cool and clever stuff in the pipeline. Take a look at the Whidbey and Longhorn waves of technologies, the stuff is just amazing!! I'm only just back from an amazing trip to MS Corp, where I had the pleasure (and I sincerely thank all those involved in allowing me to attend!!! ) of being involved in a Software Design Review (SDR) of Indigo!!! Sorry, can't comment but bear with me!! I will blog about the waves of technologies and hopefully give you some insightful pointers on whats in the pipeline ;) While you wait, have a peek at Richard Turner's blog; at the moment he is working on some really great whitepapers that are going to provide prescriptive guidance on developing distributed systems with the current MS stack and discusses the when, where and how to most appropriately use Microsoft's distributed systems technologies including ASMX, Enterprise Services and Remoting.

You can register for the Irish MSDN event at http://www.microsoft.com/ireland/msdn/events/msdnday.asp and if you have any q's contact me or those hard working folks in the Irish DPE team (and oh yeah, Clare, why don't you blog!! :) ).

Look forward to seeing you all there and hey, I would really like some suggestions on what to blog about?? as its hard to know what to do with so many bloggers out there??; the product guys have all of the fun ;) and will always beat us MS field folks to the punch!! Being original and revelant is an art and not a science; and as Christopher Baldwin pointed out today on his very 1st blog entry, "its about time, Or maybe more accurately, it's about making the time" and I would add its about finding the time!! which is slightly different in my book, being a consultant!

Ciao and seeya in 2 weeks?? right? ;)

btw, if you're looking to read up on what we are planning and gain some insight into the direction for Visual Studio and the related products from now, through Whidbey and Burton, and to the future? have a look at these blogs from the Developer Division leadership team. Also, and this is Very NB, Somasegar is asking "What do you want us to blog about?"; this is a VERY MUST blog to visit, we in Microsoft want to understand the ways in which our stack gets used and how you would like them to evolve?

and, oh yeah,

You can register for the Irish MSDN event at http://www.microsoft.com/ireland/msdn/events/msdnday.asp