Friday, September 18, 2015

Scheduling

Scheduling


Quartz is an open source Java library for scheduling jobs and enables any enterprise to schedule a job/task at a specific date and time (as in "cron" tool). It provides operations to scheduling/unscheduling jobs, starting/stopping/pausing the scheduler.

Computing in a cloud of Amazon or Microsoft

Computing in a cloud of Amazon or Microsoft


Below mentioned are the top Cloud Computing Companies:

  • Amazon Web Services
  • Microsoft Azure
  • Google Cloud Platform
  • IBM Cloud
  • others


Monday, July 6, 2015

Data Warehouse na BI

Data Warehouse and BI

A Data Warehouse is a subject-oriented, integrated, time-variant and non-volatile collection of data in support of management's decision making process.

Data Warehousing is the process of constructing and using a Data Warehouse. A Data Warehouse is constructed by integrating data from multiple heterogeneous sources that support analytical reporting, structured and/or ad hoc queries, and decision making.

Business intelligence (BI) is a technology-driven process for analyzing data and presenting actionable information to help executives, managers and other corporate end users make informed business decisions.

Cloud computing

Cloud computing



Cloud computing = Computing in a cloud, means storing and accessing data and programs over the Internet instead of your computer's hard drive. With Cloud computing, users can access files and use applications from any device that can access the Internet.

Cloud computing is the use of hardware and software to deliver a service over a network (typically the Internet). The cloud is just a metaphor for the whole Internet... 

Cloud computing is the practice of using a network of remote servers hosted on the Internet to store, manage, and process data, rather than a local "on-premiseserver or a personal computer.

Main types of Cloud computing:

IaaS = Infrastructure as a Service = A third party hosts elements of infrastructure, such as hardware, software, servers, and storage, also providing backup, security, and maintenance.

SaaS = Software as a Service  = sometimes called "on-demand software", delivery model in which software is licensed on a subscription basis and is centrally hosted. An example of a Cloud computing SaaS provider is Gmail.

PaaS = Platform as a Service = a platform-based service or model that provides a platform allowing customers to develop, run, and manage applications without the complexity of building and maintaining the infrastructure typically associated with developing and launching an app.

Friday, June 13, 2014

HTTP Verbs for RESTful Services

HTTP Verbs for RESTful Services


My best page about REST and HTTP "verbs"/methods is as the following:
https://spring.io/understanding/REST

when we ca read about ...

Principles of REST

Resources expose easily understood directory structure URIs.
Representations transfer JSON or XML to represent data objects and attributes.
Messages use HTTP methods explicitly (for example, the most important: GET, POST, PUT, and DELETE).
Stateless interactions store no client context on the server between requests. State dependencies limit and restrict scalability. The client holds session state.

HTTP methods

Use HTTP methods to map CRUD (create, retrieve, update, delete) operations to HTTP requests.
The most important:PUT, GET, POST and DELETE...
HTTP defines a set of request methods to indicate the desired action to be performed for a given resource. Although they can also be nouns, these request methods are sometimes referred as HTTP verbs.

The meaning and interpretation of HTTP Verbs/Methods for RESTful Services:
HTTP Verb CRUD
POST Create
GET Read
PUT Update/Replace
PATCH Update/Modify (Limited. Pay attention! ...)
Delete Delete
OPTIONS       (less important and useful... Pay attention! Sometimes not implemented.)
HEAD             (less important and useful...)


HTTP status codes
Status codes indicate the result of the HTTP request.

1XX - informational
2XX - success
3XX - redirection
4XX - client error, e.g. 404 Not Found at https://en.wikipedia.org/wiki/HTTP_404
5XX - server error

Tools for diagnose of problems with the communication: e.g. Firebug tool (with Firefox) and Chrome Developer Tools.

Thursday, March 13, 2014

HeuristicMixedException

HeuristicMixedException

javax.transaction.HeuristicMixedException is a strange problem with transaction handling not only on JBOSS Application Server... during commiting the transaction.

This a problem any dangerous inconsistencies in applications after a database crash...

A HeuristicMixedException exception thrown by the container due to a failure to commit a transaction, does not contain the reason why the resource manager failed.

see similar RollbackException, HeuristicRollbackException, SystemException in the Internet and examples at:

https://www.javatips.net/api/javax.transaction.heuristicmixedexception

Tuesday, October 8, 2013

sharding

sharding


Sharding is a type of database partitioning that separates very large databases the into smaller, faster, more easily managed parts called data shards. The word shard means a small part of a whole.

A database shard is a horizontal partition of data in a database or search engine. Each of multiple shards is held on a separate database server instance, to spread load. Some data within a database remains present in all shards, but some appears only in a single shard.

What is the difference between sharding and partitioning?

Sharding is a method of splitting and storing a single logical dataset in multiple databases.
Sharding is also referred as horizontal partitioning.