hello can u tell me how to start with api to login in messenger.

thankx in advance plz reply

hi,
checkout this page: http://developer.yahoo.com/messenger/guide/ch01s03.html

CMIIW, what "Authorization" field required is something like on Example 1.1 (line 2 - 10)
We need to sent this header for each request.
(and maybe many more header, as User-Agent string, etc.)

I use the HTTP Debugger Pro to analyze the login Yahoo Messenger step by step


STEP 1 (Request PART)

REQUEST STREAM:

GET /WSLogin/V1/get_auth_token?&login=myymid&passwd=myympass&oauth_consumer_key=dj0yJmk9VHZoOTdVajdPOFgzJmQ9WVdrOVpGbzBZV0YzTldrbWNHbzlNV
EkzTXpnMk9EUTJNZy0tJnM9Y29uc3VtZXJzZWNyZXQmeD00ZA-- HTTP/1.1
Host: login.yahoo.com
Connection: Keep-Alive

RESPONSE STREAM:

HTTP/1.1 200 OK
Date: Mon, 09 Aug 2010 01:11:04 GMT
P3P: policyref="http://info.yahoo.com/w3c/p3p.xml", CP="CAO DSP COR CUR ADM DEV TAI PSA PSD IVAi IVDi CONi TELo OTPi OUR DELi SAMi OTRi UNRi PUBi IND PHY ONL UNI PUR FIN COM NAV INT DEM CNT STA POL HEA PRE LOC GOV"
Cache-Control: private
Connection: close
Transfer-Encoding: chunked
Content-Type: text/plain

RequestToken=OIC_cldu3AbhdSZ_zRLAz.kb0eUD_XLLEVMdqhHrkpXxdrgEULB4pkv0T3jdurl3Et.
BcRKHmTVMwyuqXWJqsk_ZKwaliS1Ib7.EY94YZD8e.vDS0fgh9.NyIIQKlFkNnFWQfMRfBuDgkCYIzd9z
WcruKL6ZQIG33eX5GxT9gKhZRz.1OWGp1NlGyAjQ0Rf7QFamGOI.CC_6ZjEXgg8FhAW86z9n9LHHsNU-

STEP 2 (Request Access Token and Access Session)

REQUEST STREAM:

GET /oauth/v2/get_token HTTP/1.1
Authorization: OAuth realm="yahooapis.com",oauth_consumer_key="dj0yJmk9VHZoOTdVajdPOFgzJmQ9WVdrOVpGbzBZV0YzTldrbWNHbzlNVEkzTXpnMk9EUTJNZy0
tJnM9Y29uc3VtZXJzZWNyZXQmeD00ZA--", oauth_token="OIC_cldu3AbhdSZ_zRLAz.kb0eUD_XLLEVMdqhHrkpXxdrgEULB4pkv0T3jdurl3Et.BcRKHmTV
MwyuqXWJqsk_ZKwaliS1Ib7.EY94YZD8e.vDS0fgh9.NyIIQKlFkNnFWQfMRfBuDgkCYIzd9zWcruKL6Z
QIG33eX5GxT9gKhZRz.1OWGp1NlGyAjQ0Rf7QFamGOI.CC_6ZjEXgg8FhAW86z9n9LHHsNU-", oauth_signature_method="PLAINTEXT", oauth_signature="0ca1124eda008851bbf38e1c08261e671536da08%26", oauth_timestamp="1281316262", oauth_nonce="323039061", oauth_version="1.0"
Host: api.login.yahoo.com
Connection: Keep-Alive

RESPONSE STREAM:

HTTP/1.1 200 OK
Date: Mon, 09 Aug 2010 01:11:07 GMT
P3P: policyref="http://info.yahoo.com/w3c/p3p.xml", CP="CAO DSP COR CUR ADM DEV TAI PSA PSD IVAi IVDi CONi TELo OTPi OUR DELi SAMi OTRi UNRi PUBi IND PHY ONL UNI PUR FIN COM NAV INT DEM CNT STA POL HEA PRE LOC GOV"
Connection: close
Transfer-Encoding: chunked
Content-Type: text/plain; charset=utf-8

oauth_token=A%3DdwA3glOarlvsZY1GMv2qDajRqjsNsyeU9HgescF1RFw3ZkXD10TaKJCy3BliNF.Etc73dToWrYlzKN
_yZMhV0bI3CPvtvAnWDpmF8OCkmE_2aV8mqW0tzIpAYr6I4N1VZWxjOp9URrvWZetNmEGFZGeNJjgNdaG
VtMQrHxyunoINV2Wd6RohnkvGxC8HkofZfM5Ajpjo885CNCRLJ2XSnjzLN3Q7sas_o3x1bk39JYQJt0XT
srCmxPbeg74JquHbrCoOMhfyMvSuWB.OhVw0E.QP8y8fr8jbghbaAwgJtuD7IeJDX.jY4Hd4EjBa9494l
v.FcUYSFcVHH_5l9ZqPtRaP3NTtCno0ovJlQp6yffiY7537RaYcqexs8FadWmaocaVvuq7jgDDK_mvJnu
gHjJPeomiVieekPKEwrTVvL63PilMyntRqVx.zKbd301pF0G_rysjh31otXQfDfS1cruSZ6iEsWCXTOEZ
mII5drWrKdKZIXGHp0e3duMho79AVItVgDwLA75Pg7vucpZ.IqfYaL7GYrlsOQTRnf6xRc1mk6erePP.L
Tg_opgCd_IAZ6trwrNsA6hrEXRustv8ujfHzCBSw9ckkkyzu._p_lDOR2L8.h9wiKWYLB62ranEXAyOYg
QszwHZKxgNg2r94q_HYPvgFsYBtVgNWO5JfhPj3h8ljun7O45v_1HBwFjz.S34At3zCJhX6wcQfSKT9af
7I5PYq9RgIF7fn2VEGOJip24yyajsnCk_oEvD8RCZTwoSej01u&oauth_token_secret=cd0d618a8db13dc5be0334d511dfc2f755277c26&oauth_expires_in=3600&oauth_session_handle=AFSAW0yFwcnP1UwoEBxR_El_A7duVdMbeQ5xzx4dl.6dM2xjoPM-&oauth_authorization_expires_in=866167380&xoauth_yahoo_guid=MM3MF2Q6EWNZZ4J2EH7B7WTXQE


STEP 3 (Invoke messenger API using Access Token)

REQUEST STREAM:

POST /v1/session/?notifyServerToken=1 HTTP/1.1
Authorization: OAuth realm="yahooapis.com", oauth_consumer_key="dj0yJmk9VHZoOTdVajdPOFgzJmQ9WVdrOVpGbzBZV0YzTldrbWNHbzlNVEkzTXpnMk9EUTJNZy0
tJnM9Y29uc3VtZXJzZWNyZXQmeD00ZA--", oauth_nonce="130972080", oauth_signature_method="PLAINTEXT", oauth_timestamp="1281316265", oauth_token="A%3DdwA3glOarlvsZY1GMv2qDajRqjsNsyeU9HgescF1RFw3ZkXD10TaKJCy3BliNF.Etc73dToWrYlzKN
_yZMhV0bI3CPvtvAnWDpmF8OCkmE_2aV8mqW0tzIpAYr6I4N1VZWxjOp9URrvWZetNmEGFZGeNJjgNdaG
VtMQrHxyunoINV2Wd6RohnkvGxC8HkofZfM5Ajpjo885CNCRLJ2XSnjzLN3Q7sas_o3x1bk39JYQJt0XT
srCmxPbeg74JquHbrCoOMhfyMvSuWB.OhVw0E.QP8y8fr8jbghbaAwgJtuD7IeJDX.jY4Hd4EjBa9494l
v.FcUYSFcVHH_5l9ZqPtRaP3NTtCno0ovJlQp6yffiY7537RaYcqexs8FadWmaocaVvuq7jgDDK_mvJnu
gHjJPeomiVieekPKEwrTVvL63PilMyntRqVx.zKbd301pF0G_rysjh31otXQfDfS1cruSZ6iEsWCXTOEZ
mII5drWrKdKZIXGHp0e3duMho79AVItVgDwLA75Pg7vucpZ.IqfYaL7GYrlsOQTRnf6xRc1mk6erePP.L
Tg_opgCd_IAZ6trwrNsA6hrEXRustv8ujfHzCBSw9ckkkyzu._p_lDOR2L8.h9wiKWYLB62ranEXAyOYg
QszwHZKxgNg2r94q_HYPvgFsYBtVgNWO5JfhPj3h8ljun7O45v_1HBwFjz.S34At3zCJhX6wcQfSKT9af
7I5PYq9RgIF7fn2VEGOJip24yyajsnCk_oEvD8RCZTwoSej01u", oauth_version="1.0", oauth_signature="0ca1124eda008851bbf38e1c08261e671536da08%26cd0d618a8db13dc5be0334d511dfc2f755277c26"
Content-Type: application/json;charset=utf-8
Host: developer.messenger.yahooapis.com
Content-Length: 2
Connection: Keep-Alive

{}

RESPONSE STREAM:
HTTP/1.1 200 OK
Date: Mon, 09 Aug 2010 01:11:10 GMT
P3P: policyref="http://info.yahoo.com/w3c/p3p.xml", CP="CAO DSP COR CUR ADM DEV TAI PSA PSD IVAi IVDi CONi TELo OTPi OUR DELi SAMi OTRi UNRi PUBi IND PHY ONL UNI PUR FIN COM NAV INT DEM CNT STA POL HEA PRE LOC GOV"
cache-control: private,must-revalidate
content-length: 238
content-type: application/json;charset=utf-8
set-cookie: IM=2LZrSs4TOU9MishgAh9K04cjPlezfd4OiAVdapZVueTDZG2sA2ZvESQ_3lMjHHnkr9YhLHxN2_0Ok
CA--|3XW77aYEY7tYrRq3avE2FA--; expires=Mon, 09-Aug-2010 02:11:10 GMT; path=/; domain=.messenger.yahooapis.com
Vary: Accept-Encoding
Connection: close

{"sessionId":"gFmWq0Ls3RLri_U0lm1mlKxIBFinpMga5yo-","primaryLoginId":"myymid","displayInfo":{"avatarPreference":"2","checksum":"-1035057348"},"server":"rcore1.messenger.yahooapis.com","notifyServer":"rproxy1.messenger.yahooapis.com"}

You just almost there. After you get 501 error, add this line into your http header:
Content-type: application/json; charset=utf-8

Thx
~jimmi

lot of people getting stuck at the same place. session management. after doing everything successfully, getting stuck at session management. documentation can be improved!!