Composite UI for Service Oriented Systems – Mashup means bringing it together

This is a cross post from planetgeek.ch

This blogpost is part of a larger blog post series. Get the overview of the content here.

Slide83

A frontend is not owned by a single “thing”. It is a mashup of multiple “things” combined together to provide a single user experience. Looking at it from the deployment perspective we can say that many “things” can be deployed to the same box, many “things” can be deployed in the same app, many “things” can cooperate in a workflow and many “things” can be mashed up in the same page. Which brings us directly to service composition. Continue reading

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Composite UI for Service Oriented Systems – Immutable and stable

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This blogpost is part of a larger blog post series. Get the overview of the content here.

Slide76

Immutable data is unchangeable once it is written. An immutable data needs an identifier which allows to always return the same data no matter when it is requested or where it is request. Immutable data can be found everywhere in the real world. Continue reading

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Composite UI for Service Oriented Systems – Data outside vs Data inside

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This blogpost is part of a larger blog post series. Get the overview of the content here.

Before we dig deeper into the characteristics of a “thing” we need to talk about the explicit boundaries of a “thing” and what contracts actually mean.

Slide74 Continue reading

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Composite UI for Service Oriented Systems – Services are not webservices

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This blogpost is part of a larger blog post series. Get the overview of the content here.

But messaging alone is not enough! We need to decompose our system. Service Orientation can help us with that. Service Orientation or Service Oriented Architecture was first used in 1996 when Roy Schulte and Yeffim V. Natiz from Gartner defined it as “a style of multitier computing that helps organizations share logic and data among multiple applications and usage modes”. Unfortunately the term SOA has become a loaded term filled with misconceptions and hype. Continue reading

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Composite UI for Service Oriented Systems – Ordering and buy-in

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This blogpost is part of a larger blog post series. Get the overview of the content here.

Slide65

Never assume messages will arrive in the order you sent them. If it works fine on your machine that doesn’t mean it will do the same in your production environment. Continue reading

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Composite UI for Service Oriented Systems – More message patterns

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This blogpost is part of a larger blog post series. Get the overview of the content here.

Slide61

I briefly mentioned that the message has a body. The body carries on the payload or the actual business data identified by the message. Furthermore a message can contain metadata on its header. This allows the message to carry on additional information which can be consumed by the receiver side. Message forwarders need to make sure that the headers remain intact during the communication process. This means a forward should only append additional information to the metatadata or body but never remove information. Leveraging the metadata which can build up more message patterns. Continue reading

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Composite UI for Service Oriented Systems – Messaging and fault tolerance

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This blogpost is part of a larger blog post series. Get the overview of the content here.

Slide55

Consider a classical application approach where clients invoke remote procedure calls on the server. Now, what happens to the initiating request when a crash occurs? For example when the IIS App pool recycles or a connection has been refused by the remote host when too many transactions are waiting to time out. The initiating request is lost or if you are lucky somewhere present as cryptic information in a log file. Continue reading

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Composite UI for Service Oriented Systems – Messaging vs. RPC

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This blogpost is part of a larger blog post series. Get the overview of the content here.

Slide51

In the beginning, RPC style communication seems to be better performing than messaging. But when the load on the systems increases and no more threads are available the RPC performance decreases. One cause of the RPC performance decrease is the need to acquire threads from the thread pool and to allocate memory for the parameters of each request. A messaging infrastructure can deterministically assign a number of threads to handle incoming messages. Message consumers can be horizontally scaled out if the load increases. Of course the infrastructure must be provisioned with enough hardware so that the message queue for the incoming requests does not explode. Continue reading

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Composite UI for Service Oriented Systems – Messaging Introduction

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This blogpost is part of a larger blog post series. Get the overview of the content here.

Slide48

Messaging can help to reduce coupling in your system. It also addresses some of the fallacies of distributed computing. But messaging is no silver bullet. You have to carefully choose according to your non-functional requirements, risk analysis, fallacies and more whether it makes sense to use messaging. Messaging can take place inside the same process boundaries (i.e. with Event Aggregators) or over process boundaries. To leverage to full benefit of messaging often a combination of in-process and out of process messaging is used. Let us briefly explore some of the basics about messaging. Continue reading

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Composite UI for Service Oriented Systems – Coupling

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This blogpost is part of a larger blog post series. Get the overview of the content here.

Slide33

Coupling is a measure of dependencies. If a component X depends on Y, then there is coupling between them. There are two kinds of coupling: Afferent and Efferent coupling. Continue reading

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