Service oriented

Written on 8 April 2016, 05:19pm

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Web Service: exposing functionality/information from one system to another system. “A web service differs from a web site in that a web service provides information consumable by software rather than humans.

WSDL (Web Services Description Language) is an XML document describing a web service.

SOAP (Simple Object Access Protocol) is an XML-based protocol that allows the exchange of information between applications over another protocol (HTTP).

API (Application Programming Interface) represents set of rules, a contract between 2 software programs.

REST (Representational State Transfer) is a set of design principles for network communication. Constraints for the network:
– client-server
– stateless
– unique representation of resources (URI)
– manipulation of resources through representations (not by commands, for instance)

How SPDY is making the web faster

Written on 28 January 2014, 12:09pm

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SPDY is one of the things that keeps me busy 🙂 The people from Akamai came up with a nice video explaining how Google’s SPDY experimental protocol leads to defining the next version of HTTP.



The current HTTP 1.1 exists since 1999 (and hardly changed since 1996)


1. HTTP headers

– SPDY offers header compression (with HTTP 1.1 only the HTTP content is compressed)
– SPDY will avoid sending HTTP headers with every single request

2. Parallel requests

HTTP 1.1 pipelining: multiple requests on a single connection; but the response must come in the same order they were requested. Browsers open like 6 concurrent connection for every host
SPDY – true multiplexing: send as many requests as you want at once; get responses in whatever order (even in pieces). All this, over a single SPDY connection.
But this requires prioritization. SPDY leaves the decision to the server, but SPDY allows the client to mark priority requests (ex JS, CSS).

3. Server Push and Server Hint

The server can push data to the client – if the client previously established a SPDY connection.
This can be also used for sending assets to the client (ex CSS). To avoid unnecessary pushing of cached data, SPDY provides Server Hint (a suggestion to the client).


– HTTPS needs to be used to hide SPDY
– Multiplexing happens on a per host basis (so if content comes from multiple hosts, SPDY improvements are not so visible)
– Limited browser support


SPDY pushed the IETF to define the next version of HTTP: HTTP 2.0 is expected in 2014.
See more:

Update, 9 February 2015: Hello HTTP/2, Goodbye SPDY