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SOA 1 class per service Juval Lowy framework
I posted this a year ago....
I'm really against this make each class a separate service concept.
It reminds me of the Microkernel and especially workplace OS but worse.
The idea of microkernels was each service ( like memory) was an easily managed entity with carefully defined inputs and outputs which could be consumed.)
Workplace OS took this to limit and performance was so poor that no amount of optimization would help. So they had no choice but to scrap the project ( were talking $2B 10 years ago)
the bad thing is once such a design is made and implemented just like workplace OS...
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Is SSL really secure/too much security
Is SSL really secure ? By encrypting messages on the wire people get the feeling its secure and people use it ubiquitiously.
Is encrypting on the wire something that really helps ? I don't really think so , with most networks it is VERY difficult and practically impossible to do .
eg
- In a LAN you need physical access to put a device in between reading all traffic from a PC ( in which case you have bigger problems)
- Switched mean a machine tap is not very usefull ( html is not broad cast)
- You need admin access...
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Why should you use an Event Driven Architecture (EDA)?
There is a lot of documentation on EDA and people working with SOA and call backs will naturally gravitate to EDA , but i have often wanted a simple reason why. Here i will attempt this and focus on service based EDA's.
1. It Naturally mirrors organisations.
High level EDA events are business events. With EDA anybody may receive these events and act accordingly. This means extending events to new applications is a trivial excercise.
2. Low integration costs
Integration expenses are massive, EDA makes it really easy for systems to communicate even more so than SOA's which require writing a...
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SOA and Cloud computing
Great article from Zapthink. . Especially
"
the ESB has been far too central in organization’s discussions about SOA. The logic goes that all you need to do is develop a bunch of Web Services, plop them on an ESB and voila, you have a SOA. Isn’t it amazing that you can get architecture without actually doing architecture? As ridiculous as this might sound, for many organizations, this approach represents fully their SOA strategy. But, the movement to cloud computing throws the ESB “strategy” out the window.
In the cloud computing world, you have no visibility into the infrastructure, nor do...
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Eventing with and without Topics
While WS-Eventing has no support for Topics ( see last post) it is almost essential for efficient processing of messages if you have a large amount of subscriptions.
Consider the case of 10,000 Subscriptions for 10,000 Notification you are looking at 10^8 expensive xPath comparisons which will bring many servers down to its knees.
With EDA we can easily solve this problem ( compare to an overloaded DB) .
Lets say we have a Topicless share pricing feed something like
<Trades>
<Trade>
<Symbol>BHP</Symbol>
<Price>38.12</Price>
<Volume>10000</Volume>
<Exchange>ASX</Exchange>
</Trade>
</Trades>
Now WS-Eventing has a really nice feature in that subscriptions can force notifications to contain a header this header can...
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POS or SOA Lite TODO
I think Service Orientation has gone the way of J2EE/ EJB and needs to be pulled back like was done with POJO.
I propose POS Plain old Services or POSA for Plain old services architecture.
Rules.
1) There is only one rule and that is KISS.
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Why use Queues ( MSMQ) in services ?
Queues love them or hate them seem to be pretty popular. I'm definetly on the hate side especially persistant queues
Lets look at some recommendations
Use private queues. Very few applications need public queues and the performance hit is substantial.
Use non-transactional queues. Again, very few applications need transactional queues.
System.Messaging is messed up in a lot of ways, but you can work around that.
Use the asynchronous methods of System.Messaging (BeginReceive and BeginPeek) where possible.
Learn to build your own formatter for System.Messaging.
I...
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.Net services message persistance
Well looks like .Net services doesn't have persistant messaging ( no queues or persistance of subscriptions ) . This will probably be address in v2 . There is a 30 second message buffer for polling replies but this is not the same.
This is especially an issue for mobile computing ( PDAs , phones etc which are often offline) and for wrapping legacy systems. Though its unlikely that legacy systems will be wrapped by .Net services ( more likely the service bus will redirect it to locally hosted services) .
Im not a big fan of queues however. See post.
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What is Azure Services ?
Are Azure services a cloud or are they an ESB ?
While Azure does not have this it has FAR more than most ESB in terms of connecting clients to services. Sure it has router support
Azure >> ESB (Internet hosted , with integrated internet security , scalable)
Azure >> Cloud computing ( not just Client - Service routing and hosting but also it has sender-receiver relay , multicast , firewall pass through , and enterprise-cloud security integration)
The big thing is people see it as a cloud .. however i think the biggest thing is it can redirect clients...
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Windows Azure services - First impressions
I have been looking at the PDC cast of Windows Azure and all I can say is wow.
At first i thought it was just another cloud but its a new generation compared to other offerings and most important its designed to win corporates. Integrating with current enterprise systems in a secure manner will be the key.
Will it succeed - certainly ( barring some outage disasters which will hurt them bad) . However it wont succeed just for Web 2.0 ( of which i am sceptical in the long term) but think of corporate laptops ,PDAs , small offices...