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SIP Register and Kamailio AoR No ratings yet.

The RFC 3262 said: https://tools.ietf.org/html/rfc3261#section-10 The To header field contains the address of record whose registration is to be created, queried, or modified. That means TO contains AoR, and it should be some sort of sip uri. Normally we will see display name part in front of the sip uri. So if we send sip • Read More »


quick sort No ratings yet.

Quick sort High level code are quite simple ( divide/conque, recursively partition the array): void quickSort(int arr[], int low, int high) {     if (low < high)     {         /* pi is partitioning index, arr[p] is now            at right place */         int pi = partition(arr, low, high);         // Separately sort elements before         // partition and after partition • Read More »


Heap and Heapsort No ratings yet.

Heap/Heapsort is not difficult to understand when you reading online articles/watching online videos, but without using it everyday, it is quite easy to forget the evil details. Here are some notes to help memorizing this. (1) Min/Max heap, is a  a Complete Binary Tree with its parent nodes smaller or greater than its two children. a A • Read More »


openstack 5/5 (1)

I spent several days to install openstack on debian 8 at one testing box with two NICs. Finally got a basic working system! It has with a controller node running neutron, glance and horizon, a compute node using KVM. To get much speed, one KVM VM is created as a controller node on that box, at the same • Read More »


docker No ratings yet.

Finally I got some chances to package one application using docker, here are some useful commands docker images: docker build –rm -t my_tag docker_dir ( with Dockerfile) docker images , docker rmi ( remove docker image) docker containers docker run -d –publish 9080:80 –publish 1022:22 –name container_name –restart always –voloume host_dir:container_dir -e HOST_UID=$(id -u) $tag • Read More »


Go Language vs C/C++ 3/5 (2)

I have spent several days on Go. It is a little more similar to C, not C++. As it has no class concept, only structure.  Also it has pointer ( but no pointer arithmetic), interface. Also it has slice, map, go routine( for multi-thread) which make it unique. Overall it is could be a good language. Here • Read More »


What’s the difference between BNF, EBNF, ABNF, ASN.1 ? 1/5 (1)

Abstract Syntax Notation One (ASN.1) is mainly for binary protocol, it is a standard and notation that describes rules and structures for representing, encoding, transmitting, and decoding data intelecommunications and computer networking.. A good tools like asn1c can convert ASN.1 to C structure, encoder/decoder. BNF, EBNF, ABNF are for text format parsing. In terms of power, • Read More »



fp-tree and fp-growth in plain english No ratings yet.

The normal use case is to discover interesting relations between variables in large databases, e.g: i(t) 1 ABDE 2 BCE 3 ABDE 4 ABCE 5 ABCDE 6 BCD the above are some transactions, let’s A, B, C … are some products people bought. we want to find which set are frequent set .e.g: BC  is • Read More »