play-hard-work-hard

Text Extraction From URL by Scala

In this post, we talk about how to extract text from URL. Please note, we not involve special pages (e.g. Facebook posts, Facebook comments, etc) into this talk. But in another post, I will write a solution for Facebook posts extracting.

Play Framework(12)-template engine

Concept:

Templates are complied as standard Scala functions, following a simple naming convention. If you create a views/Application/index.scala.html template file, it will generate a views.html.Application.index class that has an apply()…

MySQL(3)-Joins

• left join = A
• select <select_list> from tableA A left join tableB B on A.key=B.key
• inner join = (common part between A and B)
• select <select_list> from tableA A inner join tableB B on A.key=B.key

Scala (20) — Execution Context

Execution Context:

• An ExecutionContext is similar to an Executor: it is free to execute computations in a new thread, in a pooled thread or in the current thread (although executing the computation in the current thread is discouraged)

Scala (19) — Futures

Futures

• They hold the promise for the result of a computation that is not yet complete. They are a simple container- a placeholder. A computation could fail of course, and this must also be encoded. a Future can be in exactly one of 3 states:

Akka (7) -Configuration

There are serval places which we can configure Akka:

• log level and logger backend
• enable remote
• message serializers
• definition of routers
• tuning of dispatchers

Play Framework (11) — Basic Concept

Play Framework is event-driven server. NodeJS is threaded server.

Non-blocking IO

• build on top of Netty
  Netty is an asynchronous event-driven network application framework for rapid development of maintainable high…

Akka (6) — Mailbox

An Akka Mailbox holds the messages that are destined for an Actor. Normally each Actor has its own mailbox, but with for example a BalancingPool all routes will share a single mailbox instance.