Wearable Health and Fitness Devices

My latest interest.

Apple Watch  has API access
Fibit  has API access
Garmin  has API access
Mio  Integration Workaround?
Polar  has API access

Redis Cache Time Out on Local Machines

I have encounter this problem once in a while, but now I get it all the time, it’s a time to fix.  Here is my error.

Timeout performing GET notification-43fc9640-2487-46d6-b56a-18f5f8a31d81, inst: 1, queue: 2, qu: 0, qs: 2, qc: 0, wr: 0, wq: 0, in: 0, ar: 0, clientName: XX-DELL1, IOCP: (Busy=0,Free=1000,Min=4,Max=1000), WORKER: (Busy=1,Free=4094,Min=4,Max=4095), Local-CPU: 100% (Please take a look at this article for some common client-side issues that can cause timeouts: https://github.com/StackExchange/StackExchange.Redis/tree/master/Docs/Timeouts.md)

I have now learn to follow the error message carefully and precisely.  So I follow the link.

Are you getting network or CPU bound?  Yes, I think so.

It said;

Verify what’s the maximum bandwidth supported on your client and on the server where redis-server is hosted. If there are requests that are getting bound by bandwidth, it will take longer for them to complete and thereby can cause timeouts. Similarly, verify you are not getting CPU bound on client or on the server box which would cause requests to be waiting for CPU time and thereby have timeouts.

OK, my local machine (Dell laptop) isn’t having enough CPU power or Network?





It looks like I am not having enough bandwidth? Are there commands taking long time to process?

I have about 300 keys, not even close to putting any weight no Redis, so I am crossing this out.

Was there a big request preceding several small request to the Redis that timed out?  “qs” tell how many request were sent from the client to the server.

inst: 1, queue: 2, qu: 0, qs: 2, qc: 0, wr: 0, wq: 0, in: 0, ar: 0

qs is 2, that number 2 doesn’t tell much but I always see 2 aka not increasing, so this 2 can’t be hardly any damage to the service.. so I am crossing this out too.

Are you seeing high number of busyio or busyworker threads in the timeout exception?

Well, let’s see.

IOCP: (Busy=0,Free=1000,Min=4,Max=1000), WORKER: (Busy=1,Free=4094,Min=4,Max=4095), Local-CPU: 78.48%

It said, when the number of Busy threads is great than Min threads, you are likely paying a 500ms delay before network traffic is processed by the application.

I get 1 buys, and 4 min, so I am not getting delay here.

This only happens on local machine, which is a distance way from where Azure sits.  This may be it? The recommendation was that Redis cache sits at same region.

OK, this isn’t solving my problem.  Farther more search. I came to https://gist.github.com/JonCole/db0e90bedeb3fc4823c2.

Different sized client machines have limitations on how much network bandwidth they have available. If the client exceeds the available bandwidth, then data will not be processed on the client side as quickly as the server is sending it. This can lead to timeouts.

And recommended solution was basically saying, try to minimize the use of network bandwidth.  Not exactly what I want to hear, but let’s try this.

Closed most of my Chrome windows, closed Skype, Skype Business anythings that is eating up the network usage.

Um.. 🙁 not solving the problem at all.

So far, my suspicion is that I am calling Redis at bad timing.  I am accessing to Redis cache at time when Shared Parent View Frame, and all other cache accessing works OK.

Making Notification Center with Redis Cache

In your web service there is a time you want to let user know that they have got comment on their post, got message, got news etc.  Like ones that I see on top right at Facebook, Twitter.  Today I want to make the same thing using Redis Cache.

In-memory cache is a good choice when it comes to frequently accessed and disposable data.  Redis Cache is even nice that they can store structure data.  For C#ers, you can define data model and just insert up and fetch from cache into the model.

Continue reading “Making Notification Center with Redis Cache”

Making Android App with Xamarin 3 – Connecting with ASP.Net Identity

Many of ASP.Net guys or girls are taking great feature of ASP.Net Identity to manage credential of their web services.  When offering same service via App, it is nice to be able to use the same credential management.

Continue on from  Making Android App with Xamarin 2 – Get InsntaceID. Now that we know how to get InsntaceID to identify the app, we will connect this ID with ASP.net Identity.

Continue reading “Making Android App with Xamarin 3 – Connecting with ASP.Net Identity”

Making Android App with Xamarin 2 – Get InsntaceID

Continue on from the previous article on Making Android App with Xamarin 1 – Splash Screen.  Let’s now make sure the device has valid credential, and if not ask user to input their login information.

Since TWC handles sensitive personal information I want to make sure the app is secured.  So there will be two way authentication to manage credential and devices.

There are two things that can happen, when they launch the app.

  1. The user is already a member, already registered via web service.
  2. The user is new want to register as a member.

If the case, user is a member, then;

First get device ID and see if it is valid to move forward.

If valid then move forward to the main Activity, if not, then get ready link that device ID and credential information.

Continue reading “Making Android App with Xamarin 2 – Get InsntaceID”

Azure Search, Deleting A Document

Here is how to delete a document in your Azure Search Index collection, using Azure Search SDK for .Net version 1.1.0

Reference: https://msdn.microsoft.com/en-us/library/azure/microsoft.azure.search.models.indexbatch.delete.aspx#M:Microsoft.Azure.Search.Models.IndexBatch.Delete(System.Collections.Generic.IEnumerable{Microsoft.Azure.Search.Models.Document})

I shall put full run through tutorial on Azure Search .. soon soon.

Agile Project

Agile project management is about

  • continuous improvement
  • scope flexibility
  • team input
  • delivering products

which are all great things when it comes to developing web services in team.  If you want to run a well managed project, read http://www.dummies.com/how-to/content/agile-project-management-for-dummies-cheat-sheet.html and follow.

On the other side of agile there is a waterfall style development.  These two models have pros and cons.  Please read, http://www.base36.com/2012/12/agile-waterfall-methodologies-a-side-by-side-comparison/.

Memo on RAID

What is RAID? RAID, abbreviation for redundant array of independent disks, is a technology to manage disk IO in multiple disks. (more accurate and detail version of definition is at Wiki (https://en.wikipedia.org/wiki/Standard_RAID_levels).

RAID has few different types and called RAID 0, 1, 2, 3, 4, 5, 6.

It’s not like I did background check on facts, but I hear, the most popular types are RAID 0 and 5 today.

RAID 0 evenly distribute data across n number disks.  It’s simple straightforward way to take advantage of adding multiple disks.  The risk, if one of the disk goes wrong, then it’s all gone.

RAID 5 distribute data across n number disks randomly, plus parity information on one of the disk, so if one of the disk is damaged, you can recover like nothing happened.

Next I will organize pros, cons, and theological speed of each RAID.