APACHE SLING & FRIENDS TECH MEETUP BERLIN, 23-25 SEPTEMBER 2013

“RESTful transactions” with Apache Sling Şenol Taş

About

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§  My Name is Şenol Taş §  Senior Computer Scientist §  Adobe in Basel, Switzerland

@thelabertasch

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Why such a boring Topic?

Because websites are…

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§  No longer simple advertisement platforms

§  Not only “online Business cards” §  Not a “nice to have” medium §  Not a “Playground” §  …..

Because websites are…

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§  Serious business §  Make $$$ §  Complex §  MUST have §  “Real” Applications

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Your Website IS THE Application

Let’s….

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§  Find out “what is a transaction?” §  Quick reminder about REST §  How do this two concepts work

together?

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What are Transactions?

What are Transactions?

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“An input message to a computer system that must be dealt with as a single unit of work”

What are Transactions?

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§  begin transaction §  debit checking account §  credit savings account §  update history log §  commit transaction

What are Transactions?

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§  Late 70s: Jim Gray defined the semantic of reliable transactions

§  Early 80s: Andreas Reuter and Theo Härder defined the acronym “ACID” in their paper “Principles of Transaction-Oriented Database Recovery”

ACID

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§  Atomicity §  Consistency §  Isolation §  Durability

How do tools like hybernate help?

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What is REST?

What is REST?

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§  Representational State Transfer §  Stateless §  Client-server §  Cachable §  Scalable §  …..

What is REST?

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§  So? How does this work together with transactions?

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REST and transaction is a oxymoron

REST and transactions

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§  Atomicity §  Consistency §  Isolation §  Durability

What are the challenges?

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§  HTTP REQUEST – RESPONSE PATTERN

§  STATELESS §  …..?

Change your mindset…

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§  Not everything has to be done in one request

§  If you are using POST.jsp or similar in Sling, most likely something is wrong

§  Events and Observations are your friends

§  Use the full power of the Sling Default Post and GET Servlet

Remember the cheat sheet from Lars?

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Example

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§  Resource: /home/senol/profile

§  Begin transaction §  change interests §  Commit transaction

Begin Transaction

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§  Copy the node /home/senol/profile to /home/senol/transactions/profile/*

Change interests

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§  Update with regular post request

Commit transaction

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§  With observation or events

§  Directly

Things of interest

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§  Communicating with services layer §  Distributed transactions §  Nested transactions §  Locking…

§  Using Adobe CQ? §  Have a look at the Workflow Launcher!

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Thank you and have a RESTful Day!