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Tech Tips, Tricks & Trivia

by 'Anil' Radhakrishna
An architect's notes, experiments, discoveries and annotated bookmarks.

Search from over a hundred HOW TO articles, Tips and Tricks

Azure Redis Cache - Basic, Standard, Premium Tiers

Monday, June 26, 2017
As part of my learning, I keep looking out for info presented through tables & comparison charts as they summarize lengthy topics & are useful to review what I learn. I post them with the tag ComparisonChart to revisit occasionally. 

Azure Redis Cache is a distributed, managed cache that helps you build highly scalable and responsive applications by providing you super-fast access to your data. Unlike traditional caches which deal only with key-value pairs, Redis is popular for its highly performant data types.

The below comparison table is from the Azure Redis Cache Pricing chart with additional notes gathered online -

Basic Standard Premium
Ideal for Development / testing Production ready Cache with master / slave replication Enterprise ready tier which can be used as a cache and persist data. Designed for maximum scale and enterprise integration
Cache Yes Yes Yes
Replication and Failover - Yes Yes
SLA - 99.9% 99.9%
Configure Redis (Keyspace notifications etc.) - Yes Yes
Redis Data Persistence - - Yes, persisted in Azure Storage Account
Redis Cluster - - Yes, to create caches larger than 53 GB, or to shard data across multiple Redis nodes
Scale Out to multiple Cache units - - Yes
Azure Virtual Network - - Yes, allowing  only clients within a specified network to access the Cache
Memory Size 250 MB - 53 GB 250 MB - 53 GB 6 GB - 530 GB *
Network Performance Low - High Low - High Moderate - Highest
Maximum number of Client connections 256 - 20,000 256 - 20,000 7,500 - 40,000
Import/Export - - Import can be used to bring Redis compatible RDB file(s) from any Redis server running in any cloud or environment, including Redis running on Linux, Windows, or any cloud provider such as Amazon Web Services and others. Export allows you to export the data stored in Azure Redis Cache to Redis compatible RDB file(s).

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Web Sockets - Usage Scenarios

Sunday, June 25, 2017
WebSockets provide a mechanism for fast, secure two-way communication between a client and a server over the web using HTTP(S).

WebSockets is a good choice over HTTP in usage scenarios where the following attributes are required-
* Fast Reaction Time
* Ongoing Updates
* Ad-hoc or “fire and forget” Messaging
* High-Frequency Messaging with Small Payloads

Some typical usage scenarios are:
* Location-based apps
* Collaborative editing/coding
* Financial tickers
* Sports updates - Football scores from the previous week’s game are highly cacheable because they are stable and unlikely to change, so HTTP would be a good fit. Football scores from a game in progress, however, are likely to change frequently. In that case, the resource is not highly cacheable, so a WebSocket becomes the better fit.
* Multimedia chat
* Multiplayer games
* Collaborative drawing on a digital communal chalkboard
* Clickstream data - to track user interactions on a website

A high level comparison of HTTP and WebSockets from the Windows Developer blog -

HTTP 2.0 connections could be used in place of a WebSocket depending on how they will be used as they have bi-directional messaging abilities, but they must follow the request/response pattern.

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This Week I Learned - Week #220

Saturday, June 24, 2017
This Week I Learned -

By using the long-term backup retention feature of Azure SQL Database, you can “store your SQL database backups in an Azure Recovery Services vault for up to 10 years”.

Web Application Firewall (WAF) Application Gateway provides you with all the benefits of a Basic Application Gateway, as well as protection against malicious web requests. WAP is a feature of Application Gateway that provides centralized protection of your web applications from common exploits and vulnerabilities.

App(lication) Insights not only allows monitoring but also allows you to manage application performance. It works with live web applications that are developed using .Net, Java, Node.js and can be deployed on-premise or in the cloud. 

In order to monitor live desktop and mobile apps, Microsoft recommends the use of HockeyApp platform. 

Azure Advisor blade integrates with Security Center to come up with recommendations around high availability, performance, security and cost.

Microsoft System Center Operations Manager (SCOM) is a cross-platform data center monitoring system for operating systems, hypervisors, network and hardware. It uses a single interface that shows state, health and performance information of computer systems.

OMS is an IT operations management solution from Microsoft that is available as a cloud service, It can manage both on-premise and cloud environments. The OMS suite consists of components for log analytics, automation, backup, disaster recovery, security and compliance - Simple Talk

* Google Maps has started posing questions about places you've been to. These can be turned on & off with Notification settings.

..the Frightful Five: Amazon, Apple, Facebook, Microsoft and Alphabet, the parent company of Google now dominate much of the global economy. Their growth has prompted calls for greater regulation and antitrust intervention. There’s rising worry, too, over their softer, noneconomic influence over culture and information — for instance, fears over how Facebook might affect democracies — as well as the implicit threat they pose to the jurisdictions of world governments.

* "Amazon is ...a kind of butler in the sky" - Farhad Manjoo

* Unlike competing assistants (like Apple’s Siri or Google Now), Amazon's Echo can be activated hands-free from far across the room (Siri only works from a couple of feet away), and it can decipher your voice in noisy environments, even when it’s playing music. Compared with the trudge of chatting with Siri, speaking to Alexa feels natural, closer to speaking to a human than a machine - NY Times

* Reed Hastings' Netflix is worth $65 billion and has 100 million subscribers

AppLabs, an independent software testing company with 2,500 professionals, to Computer Sciences Corporation in September 2011 for Rs 1,200 crore (Rs 12 billion), giving 10 times return on investments to Series-A investors such as Westbridge and Sequoia Capital India, Sashi Reddi returned to his original passion - investing in start-ups. The founder and managing partner of SRI Capital, a Hyderabad-based seed-stage venture capital fund with an initial corpus of Rs 100 crore (Rs 1 billion), Reddi has in his portfolio start-ups such as Glassbeam (machine log analytics for technology support), ThinCI (graphics chip design firm), Identropy (identity management services firm), Edutor (tablet-based e-learning player), iMomentous (mobile-based talent engagement platform), Hello Curry (quick service restaurant chain), YuppTV (live Internet TV channel streaming platform), GIBSS (green energy leader), and NumberMall (hyperlocal marketing) - Rediff

NumberMall started out as a phone recharge business but is now evolving to using that customer data to provide hyperlocal offers to customers from nearby merchants.

India’s stock market capitalization has crossed $2 trillion. This makes India the 9th largest equity market globally and second largest amongst the emerging markets after China. This rally in market cap has pushed India’s market cap to GDP ratio at 0.88. The 10 year average for India’s market cap to GDP ratio is 0.78, it had peaked at 1.48 in 2007. India's contribution to global Mcap has risen to a six-year high of 2.7% against a six-year average of 2.2%, whereas India's contribution to global GDP is 2.9%, up from 2.4% in 2013. Typically, the M-cap-to-GDP ratio is anywhere between 0.2 and 0.8 for emerging markets while it moves in a wider range of 0.5-2.2 for developed markets. Emerging markets such as Brazil and Mexico have among the lowest M-cap-to-GDP ratios of 0.18 and 0.27, respectively, thanks to their higher dependence on commodities amid falling prices. For France and Germany, it's at 0.67 and 0.47, respectively, even though their benchmark indices are at new highs.

Ramadan ..is a month when Muslims take time to reflect on their own paths of personal and spiritual growth.

* Three South American countries hold over half the world’s lithium. Lithium-ion batteries store energy that powers mobile phones, electric cars and electricity grids (when attached to wind turbines and photovoltaic cells).

* "What? Why did it break? The parts are of the highest quality. They come from the China of China: India" - Homer Simpson in Season 28, Episode 18

* “The essence of strategy is choosing what not to do” - Michael Porter

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Where are Azure Data-Centers located & what Services do they host?

Sunday, June 18, 2017
Azure is generally available in 34 regions around the world, with plans announced for 6 additional regions - as of June 2017
The following links provide the most up to date info -


This Week I Learned - Week #219

Saturday, June 17, 2017
This Week I Learned -

* All newly created Azure SQL databases will automatically be protected with Transparent Data Encryption (TDE). TDE is SQL’s proven encryption-at-rest technology that is required by many compliance standards to protect against theft of storage media. Customers can manage the TDE encryption keys and other secrets in a secure and compliant management using Azure Key Vault - Azure Blog

* The Virtual Machines Readiness Assessment tool will automatically inspect your on-premises environment, whether it is physical or virtualized, and provide you with a check list and detailed report on steps you need to take to move your environment to the cloud.

* The free Virtual Machine Optimization Tool automatically inspects SQL Server, Active Directory, and SharePoint deployments and provides a detailed set of prioritized recommendations and step-by-step instructions for improvement. Aimed especially at IT pros, this tool is a companion to the Virtual Machine Readiness Assessment Tool - Azure Edu

Google's  Project Sunroof Data Explorer combines machine learning with imagery from Google Maps and Google Earth to provide an estimate of how many houses in an area have solar installations.

Alcohol consumption is illegal in Bihar, Gujarat, Lakshadweep, Manipur, Nagaland. Each state's Excise department also decides how many bottles of alcohol can be kept at home. A Mumbaikar can officially store 48 beer bottles of 650ml each at home or 24 wine bottles (750ml) or 16 hard liquor bottles (750 ml) for a month. India leads the world in the consumption of alcohol while the US, China, Russia and the UK have very high beer consumption. As much as 93% liquor consumption in india is of hard liquor if the pure alcohol content per litre is considered. Beer, on the other hand, makes up a mere 7%. Maharashtra is its largest producer of wine in India.

* A Ola cab can be booked not just from the app but also a desktop browser. If you're an existing user, it will show your past ride history

Kochi metro covering 13kms was built at a cost of Rs 5,181 crore and was built over 4 years.

* "We suffer more often in imagination than in reality" - Seneca

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