Pertanyaan diatas memang sering kali muncul dikalangan orang awam. Secara etimologi, kata telepati berasal dari kata “TELE” yang berarti “Jauh” dan kata “PATHOS” yang berarti “Perasaan”. Karena itu dapat diambil kesimpulan bahwa telepati merupakan suatu kemampuan untuk merasakan segala sesuatu dari jauh. Disadari atau tidak, kita sebenarnya sering mengalami gejala-gejala dari telepati tersebut. Gejala tersebut misalnya ketika hendak mengatakan sesuatu kepada teman, namun secara bersamaan teman kita pun mengatakan perkataan yang sama dengan yang hendak kita ucapkan. Atau contoh lain ketika hendak dibokong dari belakang tanpa sengaja kita menoleh dan melihat orang yang akan membokong kita.

Contoh diatas, memang terkesan sebagai suatu peristiwa yang bisa terjadi karena aspek kebetulan belaka. Penilaian ini tidak sepenuhnya salah. Namun dibalik apa yang dianggap sebagai suatu kebetulan itu, sesungguhnya kekuatan telepati sudah bekerja mempengaruhi simpul-simpul saraf reflek kita.

Pada abad 18, ada seorang sarjana swedia yang bernama Emanuel Swedenborg yang tertarik dengan Occultisme. Pernah suatu ketika dia bersama sejumlah cendekiawan sedang rapat. Namun secara tiba-tiba dia meninggalkan rapat dan segera berlari keluar sambil mengatakan ada kebakaran di Stockholm . Melihat gelagat aneh yang ditunjukkan oleh Emanuel ini, terang saja orang yang hadir menganggap dia tidak waras lagi. Namun berselang satu jam kemudian, terdengar kabar di Stockholm terjadi kebakaran yang hebat dan menghanguskan banyak rumah dikota itu termasuk tempat rapat Emanuel. Mungkin, kita menganggap peristiwa ataupun hal seperti itu biasa-biasa saja. Ya bisa jadi kita menganggapnya, sekali lagi hanya kebetulan belaka. Namun gejala-gejala semacam inilah yang dikembangkan sehingga menjadi sebuah ilmu yang kita kenal sebagai ilmu telepati.

Jika dikategorikan kedalam jenisnya, maka telepati dapat dibagi menjadi dua bagian:

1. Telepati Hikmah

Sarana yang dipergunakan dalam telepati hikmah sangat sederhana sekali, karena setiap umat islam pasti hapal surat Al Fatihah. Sebagai Ummul kitab surat Al Fatihah banyak mengandung hal-hal yang berguna untuk dunia dan akhirat. salah satunya untuk telepati. Dengan mengirimkan surat Al Fatihah dengan cara-cara tertentu kita dapat mengobati seseorang yang sedang gelisah, cemas dan stress dari jarak jauh. Ini jelas bukan kebetulan belaka.

2.Telepati Spiritual

Telepati Spiritual mempunyai banyak cara yang dilakukan si pelaku dan bermacam ritualpun bisa digelar. mulai dari yang biasa sampai yang nyeleneh pun ada. Telepati spiritual ini memang sangat populer di kalangan masyarakat kita karena kemampuannya yang dapat dipergunakan untuk berbagai hal, salah satunya untuk berkomunikasi jarak jauh.

Hal-hal penting dalam telepati

Beberapa hal yang harus diperhatikan bagi seseorang yang ingin melakukan telepati, yang terpenting adalah harus pandai mengatur posisi ruangan dimana biasanya dia melaksanakan telepati. Selanjutnya adalah :

a. Jangan memakai bau-bauan yang menyengat.
b. Jauh dari keramaian, hal ini bisa disiasati dengan melakukan telepati dimalam hari.
c. Hindari warna yang mencolok seperti merah dan kuning.
d. Hindari ruangan kita melakukan telepati dari cahaya matahari langsung.
e. Pengaturan cahaya tidak boleh terlalu terang karena dapat memecah konsentrasi kita.

Cara melakukan sugesti

Saat melakukan sugesti kita harus mampu menyatukan dan menyelaraskan perkataan dengan kehendak batin kita. Disini dapat kita pergunakan saran yang singkat, padat dan berisi. Saran yang telah diprogram harus disimpan dan direkam di alam bawah sadar kita, jangan coba-coba untuk mengubahnya sebab konsentrasi jelas akan terganggu. Ini juga dimaksudkan agar alam bawah sadar kita terbiasa menerima saran ataupun sugesti positif. Karena pada dasarnya kekuatan batin bekerja sesuai dengan apa yang diperintahkan oleh alam bawah sadar kita lebih dulu. Jadi sebelum mensugesti orang lain kita harus mensugesti batin dan alam bawah sadar kita lebih dulu.

Sugesti itu bisa keyakinan bahwa apapun sugesti yang anda kirimkan pada orang lain akan mampu mempengaruhi alam bawah sadar orang tersebut.

Cara melatih konsentrasi

Konsentrasi sangat diperlukan saat melakukan telepati, karena konsentrasilah yang sangat berperan untuk mencapai obyek yang hendak dituju. Namun untuk mencapai konsentrasi sempurnah seseorang harus rajin berlatih. Diantara latihan tersebut anda dapat melakukan dengan cara membaca buku sambil mendengarkan radio. Usahakan anda berkonsentrasi pada bacaan buku tersebut sehingga tidak mendengar lagi suara radio tersebut. sangat bagus bila anda bisa membaca abjad bolak-balik tanpa salah melafalkannya. ini berarti hampir sempurna. Kalau sudah melaluinya berarti anda akan mudah dalam melakukan konsentrasi dan telepati.

Seorang ahli telepati memang sangat dituntut harus mampu berkonsentrasi dan menciptakan visualisasi batin kepada obyek tujuannya. Visualisasi ini bisa berbentuk cahaya penghubung antara telepatis dengan obyek. Disini perlu dijelaskan bahwa pada saat berkonsentrasi anda harus mampu menghadirkan gambar orang yang akan menjadi obyek anda, dengan catatan gambar tersebut harus jelas dan tidak hilang timbul. Setelah semuanya ini anda kuasai barulah diisi dengan sugesti yang menjadi tujuan anda. Dalam kehidupan sehari-hari mungkin anda pernah melihat atau mengalami seorang paranormal bisa membaca pikiran orang yang menjadi lawan bicaranya. Bagi orang awam mungkin ini sangat menakjubkan sekali, namun tidak demikian dengan orang yang menguasai ilmu telepati. Hal ini sangat wajar bagi siapapun yang menguasai telepati, atau paling tidak sudah mampu mensugesti alam bawah sadarnya.

Berikut beberapa kiat agar telepatis tidak mampu membaca pikiran anda:

1. Buyarkan konsentrasinya

Lakukan hal-hal yang kurang berkenan di hatinya sampai dia merasa jengkel. Kalau dia terpancing berarti anda telah berhasil memecah konsentrasinya. Konsentrasi yang terpecah biasanya sulit melakukan hal yang sifatnya halus, contohnya ya telepati itu tadi.

2. Jaga jarak

Jangan sekali-kali anda berkonsentrasi dengan ahli telepati sebab bila anda berkonsultasi dengan ahli telepati berarti anda berada dipihak yang menyerah dan kalah. Dengan demikian si ahli telepati akan dapat menangkap dengan mudah gelombang-gelombang yang dipancarkan pikiran/alam bawah sadar anda. Maka diapun dengan mudah menebaknya. Telepati merupakan ilmu yang bebas nilai. Artinya, kalau ilmu ini dikuasai orang berhati mulia maka akan bermanfaat bagi banyak orang, tapi sebaliknya bila dikuasai oleh orang jahat maka sangat berbahaya sekali. Telepati, Hipnotis dan gendam sesungguhnya tiga serangkai ilmu yang memiliki daya kerja hampir sama: mempengaruhi bawah sadar obyek.

Sumber: http://haxims.blogspot.com/2009/10/rahasia-telepati.html

Jakarta – Beberapa waktu lalu muncul kasus pria membunuh istrinya karena sang istri mengubah status di Facebook menjadi single. Kasus lain, meski tak seekstrim itu, bisa muncul kapan saja hanya karena situs jejaring semacam Facebook. Lantas bagaimana meminimalisir hal ini terjadi? Beberapa ‘etika’ Facebook yang dikutip detikINET dari Msnbc berikut mungkin berguna bagi Anda.

1. Status hubungan Anda adalah keputusan bersama pasangan

Jangan pernah mengubah-ubah status hubungan Anda jika tidak didasari kesepakatan bersama antara Anda dan pasangan. Banyak kasus buruk terjadi akibat seseorang merubah statusnya secara sepihak. Jangan lupa, teman-teman Anda atau teman pasangan Anda bisa mengetahui hal ini dengan cepat.

2. Berteman dengan teman dari sahabat Anda pun ada etikanya

Ketika ingin berteman dengan teman sahabat Anda di Facebook, jangan lupakan keberadaan teman Anda yang di sini berperan sebagai ‘penghubung’. Katakan dari siapa Anda mengetahui profil mereka. Anda tak mau
dicurigai sebagai sales bukan?

3. Siapkan diri ketika berteman dengan seseorang yang pernah berkencan dengan Anda

Sebelum Anda melakukannya, lebih baik Anda siap mental dulu. Beberapa status yang dia tulis bisa jadi membuat Anda cemburu. Dibutuhkan kedewasaan untuk melakukan hal ini. Namun jika Anda tidak ambil pusing, lakukan saja.

4. Jangan banjiri profil dengan foto, video, dan komentar yang berkaitan dengan gagalnya hubungan Anda

Hal itu sepertinya tidak pantas dilakukan di Facebook. Jika Anda ingin minta simpati, teleponlah teman Anda, jangan bertanya pada orang-orang di dunia maya, apalagi di Facebook yang diakses banyak orang. Anda malah bisa dipermalukan.

5. Jangan curhat dan buka rahasia di Facebook

Jika Anda ingin curhat dan sejenisnya, lebih baik Anda tidak melakukannya di
Facebook. Gunakan saja e-mail, telepon atau lakukan saat sedang makan bersama teman Anda misalnya. Masih banyak fasilitas lain bukan? Anda tentu tidak ingin rahasia Anda diumbar oleh orang yang tidak bertanggungjawab.

6. Kenali Perbedaan antara Wall dan Message

Suatu pernyataan yang menyangkut hubungan pribadi Anda sebaiknya tidak usah terlalu diekspos. Kalimat seperti “I luv u soo much baaabyy.. I Can’t wait too see 2neit”, mungkin akan lebih cocok jika ditulis di message.

7. Jangan sekali-kali Membuat profil Palsu

Mungkin terlintas di benak Anda untuk membuat akun palsu mantan pacar yang telah menyakiti Anda. Kemudian, Anda posting hal-hal buruk tentangnya. Tentu saja, jangan pernah benar-benar melakukan hal ini. Jika aksi Anda ketahuan, orang-orang malah bisa memberi cap negatif pada Anda.

Intinya adalah jangan umbar banyak informasi tentang diri Anda apalagi yang bersifat pribadi. Anda tak akan pernah tahu apa saja yang bisa terjadi ke depannya. Ingat, dunia maya meski menyenangkan tetap penuh dengan risiko dan juga orang-orang jahat.
( sha / fyk )

Arsip Belanda itu terdiri atas delapan puluh meter bahan arsip milik Nederlands Instituut voor Oorlogsdocumentatie (NIOD, Institut dokumentasi perang Belanda).

Arsip yang dapat dibuka lewat internet itu (www.niod.nl) akan dipresentasikan pada tanggal 22 Januari di Amsterdam dan situs ini tidak hanya dalam bahasa Belanda, tetapi juga bahasa Inggris.

Dalam arsip-arsip di situs tersebut terdapat lukisan-lukisan, koran-koran Indonesia, dokumentasi pemerintah Belanda, buku harian dan catatan perkara.

Dokumentasi pemerintah Belanda dalam situs ini merupakan dokumentasi Belanda periode 9 Maret 1942 (kapitulasi KNIL/Belanda kepada Jepang), ketika tentara Jepang menguasai Indonesia sampai 15 Agustus 1945 (kapitulasi Jepang kepada tentara Sekutu).

Diantaranya bahan arsip tentang kamp-kamp pengasingan Jepang di mana bangsa Belanda dan orang Eropa lainnya ditahan di Indonesia. Kira-kira 140.000 penduduk dan militer Belanda ditahan di kamp-kamp pengasingan Jepang, antara lain di Jakarta (Kramat), Cimahi, Bandung dan di daerah Ambarawa, Jateng.

Terutama pada akhir perang, banyak tahanan yang meninggal dunia yang disebabkan kelelahan, sakit dan kelaparan.

Beberapa bulan setelah kapitulasi Jepang, foto-foto baru dibuat di kamp-kamp pengasingan Jepang. Dari periode 1942 sampai bulan Agustus 1945 dokumentasi di pengasingan hanya berupa lukisan-lukisan saja.

Kadang-kadang lukisan-lukisan itu dibuat oleh seniman yang ditahan di kamp, tetapi kebanyakan dari lukisan-lukisan itu dibuat oleh pelukis-pelukis amatir. Situs arsip ini memiliki 4954 gambar. Kira-kira 4000 eksemplar asli berada di arsip museum Museon di Den Haag dan kira-kira seribu eksemplar lainnya disimpan di NIOD di Amsterdam.

Yang paling menarik untuk para peneliti Indonesia adalah koleksi koran-koran dan majalah Indonesia dari periode tahun tersebut. Dalam situs ini 101 publikasi koran-koran dapat dilihat.

Pengunjung situs dapat membuka semua halaman-halaman koran dan kemudian memilih artikel yang dapat dibaca dengan baik.

Koleksi koran-koran Indonesia ini memiliki aneka publikasi. Diantaranya adalah Asia Raya, Bali Sinbun, Berdjoeang, Revolusioner, Sin Po, Sinar Matahari (Ambon), Soeara Pesindo dan Warta Surabaja-syuu.(*)

Source

Sejak 1 Januari 2009, pemerintah membebaskan wajib pajak yang memiliki Nomor Pokok Wajib Pajak (NPWP) dari kewajiban membayar fiskal. Namun itu hanya untuk NPWP pribadi. NPWP yang diberikan perusahaan untuk karyawannya tetap diwajibkan membayar fiskal.

Kebijakan ini menuai komplain dari sejumlah penumpang yang hendak bepergian ke luar negeri.
Seperti yang dialami salah seorang karyawan swasta di Medan bernama Hendri (38) saat ditemui di Bandara Polonia Medan, Selasa kemarin.

Hendri sebelumnya yakin, NPWP yang dimilikinya dapat digunakan untuk bepergian ke luar negeri. Namun hasil pemeriksaan petugas di bandara NPWP miliknya dinyatakan tidak valid, dan dia tetap diwajibkan membayar fiskal.

“Saya kaget NPWP yang diberikan perusahaan dinyatakan tidak berlaku dan tetap diminta Rp 2,5 juta,” ungkap Hendri.

Menurutnya, jika tidak mau membayar fiskal sebesar Rp 2,5 juta, ia harus membuat surat pengajuan pembuatan NPWP pribadi kembali.

“Saya sebenarnya masih heran, kenapa NPWP dari perusahaan saya tidak bisa digunakan. Padahal kan sama saja. Toh saya bayar pajak juga. Kalau pun tetap dikenakan fiskal, harusnya dari awal disosialisasi, jadi tidak membingungkan,” ujar Hendri.

Kepala Bidang Pencegahan dan Penyidikan (Kabid P2) Humas Kantor Wilayah Direktorat Jendral Pajak Sumut I, Jahotman Saragih membenarkan NPWP karyawan tidak valid untuk mendapatkan bebas fiskal. hal ini.

Menurutnya, NPWP yang diuruskan sebuah perusahaan untuk pegawainya hanya berlaku untuk pajak penghasilan (Pph) dari hasil gaji yang diterima oleh pegawai tersebut. “Kebijakan ini sebenarnya diterapkan untuk mendesak masyarakat untuk perduli membayar pajak. Toh, pajak ini juga merupakan elemen pembangunan juga. Saya harap semua elemen masyarakat memperhatikan peraturan NPWP ini,” jelasnya Selasa kemarin.

Menurut Jahotman, antusiasme masyarakat Sumut untuk mengurus NPWP dan membayar pajak tahunannya demikian tinggi. Dia yakin, mulai Februari 2009 separuh dari masyarakat Sumut sudah mempunyai NPWP karena kebijakan pemerintah yang mewajibkan warganya memiliki NPWP akan berdampak positif bagi negara.

“Coba lihat, hampir di setiap kantor pajak di Kota Medan selalu penuh oleh masyarakat. Mulai dari yang mengambil SPT ( Surat Pajak Tahunan) ataupun yang ingin mengurus NPWP,” ujarnya.

Kewajiban membayar fiskal ke luar negeri bagi yang tidak memiliki NPWP mulai berlaku 1 Januari 2009 hingga 31 Desember 2010. Untuk mendapatkan bebas fiskal, wajib pajak diwajibkan menyerahkan fotokopi kartu NPWP/surat keterangan terdaftar (SKT)/surat keterangan terdaftar sementara (SKTS), fotokopi paspor, serta boarding pass ke petugas unit pelaksana fiskal luar negeri.

Jika kartu NPWP dimiliki oleh Kepala Keluarga, maka anggota keluarga yang akan berangkat ke luar negeri harus menyertakan fotokopi kartu keluarga.

Berdasarkan data-data tersebut, petugas unit pelaksana fiskal akan menginput NPWP pada aplikasi yang tersedia. Bila NPWP dinyatakan valid, maka petugas akan menempelkan stiker Bebas Fiskal pada bagian belakang boarding pass yang ditujukan untuk penumpang.

Penumpang juga tetap diwajibkan membayar fiskal jika tidak dapat menyerahkan fotokopi kartu NPWP/SKT/SKTS. Bagi anggota keluarga juga bisa dikenakan kewajiban serupa jika tidak bisa melampirkan kartu keluarga atau tetap menampilkan kartu keluarga, tetapi nama penumpang tidak tercantum dalam susunan kartu tersebut.

Yang bebas otomatis adalah wajib pajak yang berusia kurang dari 21 tahun, orang asing yang berada di Indonesia kurang dari 183 hari dalam 12 bulan, pejabat perwakilan diplomatik, pejabat perwakilan organisasi internasional, WNI yang memiliki dokumen penduduk negara lain (termasuk pelajar/mahasiswa yang belajar di LN dengan menunjukkan identitas seperti kartu pelajar), jemaah haji, pelintas batas jalan darat, dan TKI dengan kartu tenaga kerja luar negeri (KTKLN).

Sementara yang bebas dengan fiskal adalah mahasiswa dengan rekomendasi perguruan tinggi, orang asing yang melakukan penelitian, TKA di 3 Pulau (Batam, Bintan, Karimun), penyandang cacat atau orang sakit yang akan berobat keluar negeri atas biaya orsos termasuk seorang pendamping, anggota misi kesenian (budaya, olahraga, agama), program pertukaran mahasiswa/pelajar, dan TKI selain dengan KTKLN.

REZA | GLOBAL | MEDAN
http://www.harian-global.com/index.php?option=com_content&view=article&id=272:npwp-karyawan-tak-valid&catid=25:metro&Itemid=53

–

Source

Dalam memberlakukan program bebas pemakaian ini, ada beberapa syarat & ketentuan yang diberlakukan yaitu:

1. Awal dan akhir akses Speedy hanya berlaku dalam rentang waktu mulai pukul 20.00 malam dan berakhir pukul 08.00 pagi.
2. Log in ataupun log out di luar waktu tersebut tetap dikenai charge seperti biasa (berlaku tarif normal). Ketentuan log in dan log out :
   • Untuk modem dengan setting mode routing, log in terhitung sejak status koneksi modem aktif dan logout terhitung sejak modem dimatikan.
   • Untuk modem dengan setting mode bridging, log in terhitung sejak Anda melakukan dial-up connection dan log out terhitung sejak Anda melakukan disconnect dari koneksi Speedy Anda.
3. Pemakaian melebihi 12 jam secara terus menerus dikenakan tarif normal.
4. Berlaku bagi pelanggan lama maupun pelanggan baru.
5. Berlaku pada 3 paket layanan Speedy limited yaitu Speedy Personal, Speedy Time based dan Speedy Profesional.
6. Tarif excess usage atau over quota tetap sesuai tarif normal.
7. Besaran kuota limited tetap sesuai aturan kuota yang berlaku.
8. Akses yang melebihi 12 jam tetap akan dikenakan charge normal, walaupun saat melakukan log in dan log out berada dalam rentang waktu free of charge. Contoh: Pelanggan melakukan akses internet dari pukul 21.00 pada tanggal 15 Juli sampai dengan pukul 21.00 pada tanggal 16 Juli 2008. Meskipun log in dan log out berada di antara waktu pukul 20.00 sd 08.00, namun lama pemakaian adalah 24 jam (melebihi 12 jam).
9. Apabila pelanggan berkeinginan melakukan pengecekan terhadap besarnya usage pemakaian Speedy pada malam sebelumnya (pemakaian antara pukul 20.00 sampai dengan pukul 08.00), dapat dilakukan setelah pukul 09.00 mengingat antara pukul 08.00 sampai dengan pukul 09.00 TELKOM akan melakukan proses cleansing data usage terkait program ini.

Untuk mempermudah pengetahuan pelanggan terhadap program ini, beberapa contoh kasus di bawah ini akan menerangkan implementasi program gratis 8 malam sampai dengan 8 pagi ini sebagai berikut:

Kasus 1. Apabila pelanggan Speedy mulai mengakses internet pukul 19.00 WIB dan berakhir jam 22.00 WIB, maka pelanggan yang bersangkutan akan dikenakan charge penggunaan dengan tarif normal (tidak free charge), karena log in dilakukan sebelum periode program. Bagi pelanggan Speedy Timebased akan dikenakan charge normal untuk penggunaan selama 3 jam, sedangkan bagi pelanggan Speedy volume based usage tetap akan dicatat sesuai tarif normal.

Kasus 2. Apabila pelanggan Speedy mulai mengakses internet pukul 07.00 dan berakhir jam 12.00, maka pelanggan yang bersangkutan akan dikenakan charge penggunaan dengan tarif normal (tidak free charge), karena pemakaian melewati periode program atau berakhir sesudah pukul 08.00 pagi. Contoh bagi pelanggan Speedy Timebased akan dikenakan charge normal untuk penggunaan selama 5 jam.

Kasus 3. Apabila pelanggan Speedy mulai mengakses internet pukul 19.00 dan berakhir jam 09.00, maka pelanggan yang bersangkutan akan dikenakan charge penggunaan dengan tarif normal (tidak free charge), karena pemakaian melewati periode program (mulai sebelum pukul 20.00 dan berakhir sesudah pukul 08.00). Contoh bagi pelanggan Speedy Timebased akan dikenakan charge normal untuk penggunaan selama 14 jam.

Tips dalam melakukan pemakaian untuk mendapatkan free of charge atau program unlimited malam hari ini adalah:

• Pastikan Anda melakukan log in dan log out dengan acuan jam yang terdapat di www.telkomspeedy.com yang telah disesuaikan dengan standar waktu Indonesia bagian barat.

• Login mulai pukul 20.00 malam (jangan kurang walau hanya 1 detik) dan logout sebelum pukul 08.00 pagi (jangan lebih walau hanya 1 detik).

• Cek pemakaian kira-kira mulai pukul 09.00 pagi harinya untuk memastikan bahwa usage Anda pada malam sebelumnya sudah dihapus.

Selamat mencoba.

SOURCE

Source

Jakarta, (ANTARA News) – Presiden Susilo Bambang Yudhoyono menyatakan, Indonesia telah lepas dari krisis ekonomi, namun masih banyak tantangan yang harus dihadapi demi menuju masa depan yang lebih baik.

Demikian petikan pidato Presiden Susilo Bambang Yudhoyono, saat membacakan keterangan pemerintah tentang Kebijakan Pembangunan Daerah pada Sidang Paripurna DPD-RI, di Gedung MPR/DPR, Jakarta, Jumat.

Menurut Kepala Negara, Indonesia lepas dari krisis, tercermin dari pendapatan per kapita masyarakat yang terus meningkat dan Produk Domestik Bruto (PDB) yang kian melonjak.

“Kita patut bersyukur, bahwa pendapatan per kapita meningkat dari tahun ke tahun. Pada tahun 2004 pendapatan per kapita baru mencapai 1.186 dolar AS, namun pada 2007 telah menjadi 1.946 dolar AS atau meningkat dengan 64 persen dalam tiga tahun,” tegas Presiden.

Angka ini diutarakannya, juga merupakan capaian pendapatan per kapita yang lebih tinggi dari masa sebelum krisis ekonomi 1998.

Sementara itu, PDB Indonesia pada tahun 2007 telah mencapai nilai sebesar Rp3.957 triliun.

Dengan PDB sebesar itu, Indonesia termasuk dalam 20 negara dengan PDB terbesar di dunia.

“Kemajuan-kemajuan ini tentu membangkitkan semangat kita untuk terus melangkah maju untuk masa depan yang lebih baik,” kata Presiden.(*)

KPI mengimbau para orangtua mendampingi anak-anaknya ketika nonton kartun Tom and Jerry dan Popeye karena banyak gambar yang tidak pantas untuk dikonsumsi anak-anak, kata Koordinator Pemantauan Langsung KPI Pusat, Yuzirwan Uyun, dalam jumpa pers di kantor KPI Jakarta, Selasa.

Yazirwan juga meminta stasiun TV yang memutar film kartun Tom and Jerry dan si pelaut Popeye mencantumkan klasifikasi acara, apakah termasuk dalam klasifikasi A (anak) dan BO (bimbingan orang tua).

Pada kesempatan yang sama, tokoh pendidikan Arief Rahman mengatakan hal yang sama.

“Kita mendapatkan informasi dari luar negeri bahwa dua tayangan itu mendapat banyak keberatan karena adanya tayangan yang tidak pantas,” kata Arief yang juga ketua tim panelis pemantau tayangan TV dari KPI untuk periode 3 bulan Juni 2008.

Kartun Tom and Jerry yang sering menampilkan si kucing Tom sebagai kucing yang sial dengan mendapat perlakuan seperti dipukul, ditendang, dilindas, dan kekerasan lain, tidak layak ditonton anak-anak.

“Kalau pada Popeye, ada adegan dimana Olive (istri Popeye) dilecehkan habis-habisan oleh musuh Popeye. Itu tidak pantas bagi anak-anak,” kata Arief.

Sedangkan anggota tim panelis Nina Armando menjelaskan Tom and Jerry dan Popeye merupakan dua dari 15 tayangan anak yang dianggap berbahaya oleh YPMA (Yayasan Pengembangan Media Anak).

Dari data YPMA, kartun Tom and Jery ditayangkan setiap hari kecuali Jumat oleh RCTI dan pada Senin – Jumat oleh TPI dan Trans7, sedangkan kartun Popeye and Son ditayangkan setiap hari di ANTV.

YPMA merilis 15 tayangan televisi yang berbahaya bagi anak-anak yiatu Tom and Jerry (RCTI, TPI, Trans7) , Crayon Sinchan (RCTI), Si Entong (TPI), Popeye and Son (ANTV), Oggy and The Cockroaches (ANTV), Mask Rider Blade (ANTV), Detective Conan (Indosiar), Dragon Ball (Indosiar), Naruto 4 (Indosiar), Carita da Angel (Global TV), Ultraman Cosmos (Global TV), One Piece (Global TV) dan Samurai X (Global TV).

Tayangan yang masuk kategori berbahaya, menurut YPMA, yaitu tayangan yang banyak mengandung muatan negatif seperti kekerasan, mistis, seks dan bahasa kasar dengan frekuensi penyiaran yang cukup tinggi dan cenderung menjadi daya tarik utama.

YPMA juga merilis 14 tayangan tv yang berkategori “hati-hati” bagi anak-anak yaitu Doraemon (RCTI), Idola Cilik Seleb dan Rapor (RCTI), Harveytoons (TPI), Transformer (ANTV), Pokemon Series 5 (Indosiar), Power Rangers SPD (Indosiar), Power Rangers Mystic (Indosiar), Scooby Doo Where Are You (Trans7), Shaggy and Scooby Doo Get A Clue (Trans7), New Scooby Doo Movie (Trans7), Avatar The Legend of (Global TV), Spongebob Squarepants (Global TV), Aang dan Skyland (Global TV).

Tayangan yang masuk kategori hati-hati yaitu tayangan yang pada umumnya baik dan memiliki nilai positif namun masih memuat adegan kekerasan, mistis, seks dan cerita yang agak rumit sehingga dipandang memerlukan kehadiran orangtua (BO/bimbingan orang tua) bila anak-anak yang menonton.

YPMA juga merilis 15 acara yang “aman” untuk anak yaitu After School (RCTI), Renovasi Sekolah (ANTV), Surat Sahabat (Trans TV), Cerita Anak (TransTV), Main Yuk! (Trans TV), Bocah Petualang (Trans7). Laptop Si Unyil (Trans7), Jalan Sesama (Trans7), Si Bolang Ke Kota (Trans7), Buku Harian Si Unyil (Trans7), Cita-citaku (Trans7), Dora The Explorer (Global TV), Go! Diego Go (Global TV), Chalkzone (Global TV) dan Backyardigans (Global TV).

Tayangan yang dikategorikan aman adalah tayangan yang tidak hanya menghibur, tetapi juga memberikan manfaat lebih seperti pendidikan, memotivasi, mengembangkan sikap percaya diri anak dan penanaman nilai-nilai positif dalam kehidupan.
(*)

Source

California – Laptop ternyata tidak hanya digunakan untuk mengetik, tapi juga bisa digunakan untuk mendeteksi gempa.

Saat ini sejumlah laptop dilengkapi dengan accelerometer yang berfungsi untuk mendeteksi benturan saat terjatuh, supaya data pada hard disk tidak hilang. Ternyata, alat yang satu ini juga bisa dimanfaatkan untuk mendeteksi gempa bumi. Sistem ini dikenal dengan Quakecatcher Network, demikian seperti dikutip detikINET dari Geek.com, Selasa (12/8/2008).

Namun, ada begitu banyak gerakan yang berasal dari sejumlah sumber yang berbeda, misalnya saat laptop terbentur, atau getaran karena gempa. Lalu bagaimana cara membedakan getaran saat terbentur dengan getaran gempa?

Memang sulit mendeteksi gempa dengan sebuah laptop tunggal, tapi jika ada ratusan atau ribuan laptop yang melaporkan pergerakan serupa dalam tempo yang sama, dan laptop tersebut tersebar di lokasi yang sama, bisa diprediksikan bahwa akan terjadi gempa.

“Saat laptop terbentur, accelerometer akan mendeteksinya. Jika getaran tersebut hanya berasal dari satu laptop, server akan tahu bahwa itu hanyalah laptop yang terbentur. Namun, jika ada banyak getaran yang dilaporkan, kemungkinan itu adalah gempa. Jika kita bisa mendeteksi gempa tersebut, kita dapat segera mengirimkan sinyal ke pihak membutuhkan, bahkan sebelum guncangan gempa itu terasa dari episentrum ke orang-orang,” demikian penjelasan Dr Jesse Lawrence, assistant professor of geophysics di Standford University.

Saat ini Quakecatcher Network baru terdiri atas 3 laptop. Namun, para peneliti berharap bisa mengembangkannya dan menciptakan sistem deteksi dini lainnya untuk gempa, sehingga orang memiliki waktu untuk menyelamatkan diri sebelum terjadi guncangan gempa.

tag: content

80% of the end-user response time is spent on the front-end. Most of this time is tied up in downloading all the components in the page: images, stylesheets, scripts, Flash, etc. Reducing the number of components in turn reduces the number of HTTP requests required to render the page. This is the key to faster pages.

One way to reduce the number of components in the page is to simplify the page’s design. But is there a way to build pages with richer content while also achieving fast response times? Here are some techniques for reducing the number of HTTP requests, while still supporting rich page designs.

Combined files are a way to reduce the number of HTTP requests by combining all scripts into a single script, and similarly combining all CSS into a single stylesheet. Combining files is more challenging when the scripts and stylesheets vary from page to page, but making this part of your release process improves response times.

CSS Sprites are the preferred method for reducing the number of image requests. Combine your background images into a single image and use the CSS background-image and background-position properties to display the desired image segment.

Image maps combine multiple images into a single image. The overall size is about the same, but reducing the number of HTTP requests speeds up the page. Image maps only work if the images are contiguous in the page, such as a navigation bar. Defining the coordinates of image maps can be tedious and error prone. Using image maps for navigation is not accessible too, so it’s not recommended.

Inline images use the data: URL scheme to embed the image data in the actual page. This can increase the size of your HTML document. Combining inline images into your (cached) stylesheets is a way to reduce HTTP requests and avoid increasing the size of your pages. Inline images are not yet supported across all major browsers.

Reducing the number of HTTP requests in your page is the place to start. This is the most important guideline for improving performance for first time visitors. As described in Tenni Theurer’s blog post Browser Cache Usage – Exposed!, 40-60% of daily visitors to your site come in with an empty cache. Making your page fast for these first time visitors is key to a better user experience.

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Use a Content Delivery Network

tag: server

The user’s proximity to your web server has an impact on response times. Deploying your content across multiple, geographically dispersed servers will make your pages load faster from the user’s perspective. But where should you start?

As a first step to implementing geographically dispersed content, don’t attempt to redesign your web application to work in a distributed architecture. Depending on the application, changing the architecture could include daunting tasks such as synchronizing session state and replicating database transactions across server locations. Attempts to reduce the distance between users and your content could be delayed by, or never pass, this application architecture step.

Remember that 80-90% of the end-user response time is spent downloading all the components in the page: images, stylesheets, scripts, Flash, etc. This is the Performance Golden Rule. Rather than starting with the difficult task of redesigning your application architecture, it’s better to first disperse your static content. This not only achieves a bigger reduction in response times, but it’s easier thanks to content delivery networks.

A content delivery network (CDN) is a collection of web servers distributed across multiple locations to deliver content more efficiently to users. The server selected for delivering content to a specific user is typically based on a measure of network proximity. For example, the server with the fewest network hops or the server with the quickest response time is chosen.

Some large Internet companies own their own CDN, but it’s cost-effective to use a CDN service provider, such as Akamai Technologies, Mirror Image Internet, or Limelight Networks. For start-up companies and private web sites, the cost of a CDN service can be prohibitive, but as your target audience grows larger and becomes more global, a CDN is necessary to achieve fast response times. At Yahoo!, properties that moved static content off their application web servers to a CDN improved end-user response times by 20% or more. Switching to a CDN is a relatively easy code change that will dramatically improve the speed of your web site.

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Add an Expires or a Cache-Control Header

tag: server

There are two things in this rule:

• For static components: implement “Never expire” policy by setting far future Expires header
• For dynamic components: use an appropriate Cache-Control header to help the browser with conditional requests

Web page designs are getting richer and richer, which means more scripts, stylesheets, images, and Flash in the page. A first-time visitor to your page may have to make several HTTP requests, but by using the Expires header you make those components cacheable. This avoids unnecessary HTTP requests on subsequent page views. Expires headers are most often used with images, but they should be used on all components including scripts, stylesheets, and Flash components.

Browsers (and proxies) use a cache to reduce the number and size of HTTP requests, making web pages load faster. A web server uses the Expires header in the HTTP response to tell the client how long a component can be cached. This is a far future Expires header, telling the browser that this response won’t be stale until April 15, 2010.

      Expires: Thu, 15 Apr 2010 20:00:00 GMT

If your server is Apache, use the ExiresDefault directive to set an expiration date relative to the current date. This example of the ExpiresDefault directive sets the Expires date 10 years out from the time of the request.

      ExpiresDefault "access plus 10 years"

Keep in mind, if you use a far future Expires header you have to change the component’s filename whenever the component changes. At Yahoo! we often make this step part of the build process: a version number is embedded in the component’s filename, for example, yahoo_2.0.6.js.

Using a far future Expires header affects page views only after a user has already visited your site. It has no effect on the number of HTTP requests when a user visits your site for the first time and the browser’s cache is empty. Therefore the impact of this performance improvement depends on how often users hit your pages with a primed cache. (A “primed cache” already contains all of the components in the page.) We measured this at Yahoo! and found the number of page views with a primed cache is 75-85%. By using a far future Expires header, you increase the number of components that are cached by the browser and re-used on subsequent page views without sending a single byte over the user’s Internet connection.

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Gzip Components

tag: server

The time it takes to transfer an HTTP request and response across the network can be significantly reduced by decisions made by front-end engineers. It’s true that the end-user’s bandwidth speed, Internet service provider, proximity to peering exchange points, etc. are beyond the control of the development team. But there are other variables that affect response times. Compression reduces response times by reducing the size of the HTTP response.

Starting with HTTP/1.1, web clients indicate support for compression with the Accept-Encoding header in the HTTP request.

      Accept-Encoding: gzip, deflate

If the web server sees this header in the request, it may compress the response using one of the methods listed by the client. The web server notifies the web client of this via the Content-Encoding header in the response.

      Content-Encoding: gzip

Gzip is the most popular and effective compression method at this time. It was developed by the GNU project and standardized by RFC 1952. The only other compression format you’re likely to see is deflate, but it’s less effective and less popular.

Gzipping generally reduces the response size by about 70%. Approximately 90% of today’s Internet traffic travels through browsers that claim to support gzip. If you use Apache, the module configuring gzip depends on your version: Apache 1.3 uses mod_gzip while Apache 2.x uses mod_deflate.

There are known issues with browsers and proxies that may cause a mismatch in what the browser expects and what it receives with regard to compressed content. Fortunately, these edge cases are dwindling as the use of older browsers drops off. The Apache modules help out by adding appropriate Vary response headers automatically.

Servers choose what to gzip based on file type, but are typically too limited in what they decide to compress. Most web sites gzip their HTML documents. It’s also worthwhile to gzip your scripts and stylesheets, but many web sites miss this opportunity. In fact, it’s worthwhile to compress any text response including XML and JSON. Image and PDF files should not be gzipped because they are already compressed. Trying to gzip them not only wastes CPU but can potentially increase file sizes.

Gzipping as many file types as possible is an easy way to reduce page weight and accelerate the user experience.

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Put Stylesheets at the Top

tag: css

While researching performance at Yahoo!, we discovered that moving stylesheets to the document HEAD makes pages apprear to be loading faster. This is because putting stylesheets in the HEAD allows the page to render progressively.

Front-end engineers that care about performance want a page to load progressively; that is, we want the browser to display whatever content it has as soon as possible. This is especially important for pages with a lot of content and for users on slower Internet connections. The importance of giving users visual feedback, such as progress indicators, has been well researched and documented. In our case the HTML page is the progress indicator! When the browser loads the page progressively the header, the navigation bar, the logo at the top, etc. all serve as visual feedback for the user who is waiting for the page. This improves the overall user experience.

The problem with putting stylesheets near the bottom of the document is that it prohibits progressive rendering in many browsers, including Internet Explorer. These browsers block rendering to avoid having to redraw elements of the page if their styles change. The user is stuck viewing a blank white page.

The HTML specification clearly states that stylesheets are to be included in the HEAD of the page: “Unlike A, [LINK] may only appear in the HEAD section of a document, although it may appear any number of times.” Neither of the alternatives, the blank white screen or flash of unstyled content, are worth the risk. The optimal solution is to follow the HTML specification and load your stylesheets in the document HEAD.

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Put Scripts at the Bottom

tag: javascript

The problem caused by scripts is that they block parallel downloads. The HTTP/1.1 specification suggests that browsers download no more than two components in parallel per hostname. If you serve your images from multiple hostnames, you can get more than two downloads to occur in parallel. While a script is downloading, however, the browser won’t start any other downloads, even on different hostnames.

In some situations it’s not easy to move scripts to the bottom. If, for example, the script uses document.write to insert part of the page’s content, it can’t be moved lower in the page. There might also be scoping issues. In many cases, there are ways to workaround these situations.

An alternative suggestion that often comes up is to use deferred scripts. The DEFER attribute indicates that the script does not contain document.write, and is a clue to browsers that they can continue rendering. Unfortunately, Firefox doesn’t support the DEFER attribute. In Internet Explorer, the script may be deferred, but not as much as desired. If a script can be deferred, it can also be moved to the bottom of the page. That will make your web pages load faster.

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Avoid CSS Expressions

tag: css

CSS expressions are a powerful (and dangerous) way to set CSS properties dynamically. They’re supported in Internet Explorer, starting with version 5. As an example, the background color could be set to alternate every hour using CSS expressions.

      background-color: expression( (new Date()).getHours()%2 ? "#B8D4FF" : "#F08A00" );

As shown here, the expression method accepts a JavaScript expression. The CSS property is set to the result of evaluating the JavaScript expression. The expression method is ignored by other browsers, so it is useful for setting properties in Internet Explorer needed to create a consistent experience across browsers.

The problem with expressions is that they are evaluated more frequently than most people expect. Not only are they evaluated when the page is rendered and resized, but also when the page is scrolled and even when the user moves the mouse over the page. Adding a counter to the CSS expression allows us to keep track of when and how often a CSS expression is evaluated. Moving the mouse around the page can easily generate more than 10,000 evaluations.

One way to reduce the number of times your CSS expression is evaluated is to use one-time expressions, where the first time the expression is evaluated it sets the style property to an explicit value, which replaces the CSS expression. If the style property must be set dynamically throughout the life of the page, using event handlers instead of CSS expressions is an alternative approach. If you must use CSS expressions, remember that they may be evaluated thousands of times and could affect the performance of your page.

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Make JavaScript and CSS External

tag: javascript, css

Many of these performance rules deal with how external components are managed. However, before these considerations arise you should ask a more basic question: Should JavaScript and CSS be contained in external files, or inlined in the page itself?

Using external files in the real world generally produces faster pages because the JavaScript and CSS files are cached by the browser. JavaScript and CSS that are inlined in HTML documents get downloaded every time the HTML document is requested. This reduces the number of HTTP requests that are needed, but increases the size of the HTML document. On the other hand, if the JavaScript and CSS are in external files cached by the browser, the size of the HTML document is reduced without increasing the number of HTTP requests.

The key factor, then, is the frequency with which external JavaScript and CSS components are cached relative to the number of HTML documents requested. This factor, although difficult to quantify, can be gauged using various metrics. If users on your site have multiple page views per session and many of your pages re-use the same scripts and stylesheets, there is a greater potential benefit from cached external files.

Many web sites fall in the middle of these metrics. For these sites, the best solution generally is to deploy the JavaScript and CSS as external files. The only exception where inlining is preferable is with home pages, such as Yahoo!’s front page and My Yahoo!. Home pages that have few (perhaps only one) page view per session may find that inlining JavaScript and CSS results in faster end-user response times.

For front pages that are typically the first of many page views, there are techniques that leverage the reduction of HTTP requests that inlining provides, as well as the caching benefits achieved through using external files. One such technique is to inline JavaScript and CSS in the front page, but dynamically download the external files after the page has finished loading. Subsequent pages would reference the external files that should already be in the browser’s cache.

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Reduce DNS Lookups

tag: content

The Domain Name System (DNS) maps hostnames to IP addresses, just as phonebooks map people’s names to their phone numbers. When you type www.yahoo.com into your browser, a DNS resolver contacted by the browser returns that server’s IP address. DNS has a cost. It typically takes 20-120 milliseconds for DNS to lookup the IP address for a given hostname. The browser can’t download anything from this hostname until the DNS lookup is completed.

DNS lookups are cached for better performance. This caching can occur on a special caching server, maintained by the user’s ISP or local area network, but there is also caching that occurs on the individual user’s computer. The DNS information remains in the operating system’s DNS cache (the “DNS Client service” on Microsoft Windows). Most browsers have their own caches, separate from the operating system’s cache. As long as the browser keeps a DNS record in its own cache, it doesn’t bother the operating system with a request for the record.

Internet Explorer caches DNS lookups for 30 minutes by default, as specified by the DnsCacheTimeout registry setting. Firefox caches DNS lookups for 1 minute, controlled by the network.dnsCacheExpiration configuration setting. (Fasterfox changes this to 1 hour.)

When the client’s DNS cache is empty (for both the browser and the operating system), the number of DNS lookups is equal to the number of unique hostnames in the web page. This includes the hostnames used in the page’s URL, images, script files, stylesheets, Flash objects, etc. Reducing the number of unique hostnames reduces the number of DNS lookups.

Reducing the number of unique hostnames has the potential to reduce the amount of parallel downloading that takes place in the page. Avoiding DNS lookups cuts response times, but reducing parallel downloads may increase response times. My guideline is to split these components across at least two but no more than four hostnames. This results in a good compromise between reducing DNS lookups and allowing a high degree of parallel downloads.

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Minify JavaScript and CSS

tag: javascript, css

Minification is the practice of removing unnecessary characters from code to reduce its size thereby improving load times. When code is minified all comments are removed, as well as unneeded white space characters (space, newline, and tab). In the case of JavaScript, this improves response time performance because the size of the downloaded file is reduced. Two popular tools for minifying JavaScript code are JSMin and YUI Compressor. The YUI compressor can also minify CSS.

Obfuscation is an alternative optimization that can be applied to source code. It’s more complex than minification and thus more likely to generate bugs as a result of the obfuscation step itself. In a survey of ten top U.S. web sites, minification achieved a 21% size reduction versus 25% for obfuscation. Although obfuscation has a higher size reduction, minifying JavaScript is less risky.

In addition to minifying external scripts and styles, inlined <script> and <style> blocks can and should also be minified. Even if you gzip your scripts and styles, minifying them will still reduce the size by 5% or more. As the use and size of JavaScript and CSS increases, so will the savings gained by minifying your code.

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Avoid Redirects

tag: content

Redirects are accomplished using the 301 and 302 status codes. Here’s an example of the HTTP headers in a 301 response:

      HTTP/1.1 301 Moved Permanently
      Location: http://example.com/newuri
      Content-Type: text/html

The browser automatically takes the user to the URL specified in the Location field. All the information necessary for a redirect is in the headers. The body of the response is typically empty. Despite their names, neither a 301 nor a 302 response is cached in practice unless additional headers, such as Expires or Cache-Control, indicate it should be. The meta refresh tag and JavaScript are other ways to direct users to a different URL, but if you must do a redirect, the preferred technique is to use the standard 3xx HTTP status codes, primarily to ensure the back button works correctly.

The main thing to remember is that redirects slow down the user experience. Inserting a redirect between the user and the HTML document delays everything in the page since nothing in the page can be rendered and no components can start being downloaded until the HTML document has arrived.

One of the most wasteful redirects happens frequently and web developers are generally not aware of it. It occurs when a trailing slash (/) is missing from a URL that should otherwise have one. For example, going to http://astrology.yahoo.com/astrology results in a 301 response containing a redirect to http://astrology.yahoo.com/astrology/ (notice the added trailing slash). This is fixed in Apache by using Alias or mod_rewrite, or the DirectorySlash directive if you’re using Apache handlers.

Connecting an old web site to a new one is another common use for redirects. Others include connecting different parts of a website and directing the user based on certain conditions (type of browser, type of user account, etc.). Using a redirect to connect two web sites is simple and requires little additional coding. Although using redirects in these situations reduces the complexity for developers, it degrades the user experience. Alternatives for this use of redirects include using Alias and mod_rewrite if the two code paths are hosted on the same server. If a domain name change is the cause of using redirects, an alternative is to create a CNAME (a DNS record that creates an alias pointing from one domain name to another) in combination with Alias or mod_rewrite.

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Remove Duplicate Scripts

tag: javascript

It hurts performance to include the same JavaScript file twice in one page. This isn’t as unusual as you might think. A review of the ten top U.S. web sites shows that two of them contain a duplicated script. Two main factors increase the odds of a script being duplicated in a single web page: team size and number of scripts. When it does happen, duplicate scripts hurt performance by creating unnecessary HTTP requests and wasted JavaScript execution.

Unnecessary HTTP requests happen in Internet Explorer, but not in Firefox. In Internet Explorer, if an external script is included twice and is not cacheable, it generates two HTTP requests during page loading. Even if the script is cacheable, extra HTTP requests occur when the user reloads the page.

In addition to generating wasteful HTTP requests, time is wasted evaluating the script multiple times. This redundant JavaScript execution happens in both Firefox and Internet Explorer, regardless of whether the script is cacheable.

One way to avoid accidentally including the same script twice is to implement a script management module in your templating system. The typical way to include a script is to use the SCRIPT tag in your HTML page.

      <script type="text/javascript" src="menu_1.0.17.js"></script>

An alternative in PHP would be to create a function called insertScript.

      <?php insertScript("menu.js") ?>

In addition to preventing the same script from being inserted multiple times, this function could handle other issues with scripts, such as dependency checking and adding version numbers to script filenames to support far future Expires headers.

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Configure ETags

tag: server

Entity tags (ETags) are a mechanism that web servers and browsers use to determine whether the component in the browser’s cache matches the one on the origin server. (An “entity” is another word a “component”: images, scripts, stylesheets, etc.) ETags were added to provide a mechanism for validating entities that is more flexible than the last-modified date. An ETag is a string that uniquely identifies a specific version of a component. The only format constraints are that the string be quoted. The origin server specifies the component’s ETag using the ETag response header.

      HTTP/1.1 200 OK
      Last-Modified: Tue, 12 Dec 2006 03:03:59 GMT
      ETag: "10c24bc-4ab-457e1c1f"
      Content-Length: 12195

Later, if the browser has to validate a component, it uses the If-None-Match header to pass the ETag back to the origin server. If the ETags match, a 304 status code is returned reducing the response by 12195 bytes for this example.

      GET /i/yahoo.gif HTTP/1.1
      Host: us.yimg.com
      If-Modified-Since: Tue, 12 Dec 2006 03:03:59 GMT
      If-None-Match: "10c24bc-4ab-457e1c1f"
      HTTP/1.1 304 Not Modified

The problem with ETags is that they typically are constructed using attributes that make them unique to a specific server hosting a site. ETags won’t match when a browser gets the original component from one server and later tries to validate that component on a different server, a situation that is all too common on Web sites that use a cluster of servers to handle requests. By default, both Apache and IIS embed data in the ETag that dramatically reduces the odds of the validity test succeeding on web sites with multiple servers.

The ETag format for Apache 1.3 and 2.x is inode-size-timestamp. Although a given file may reside in the same directory across multiple servers, and have the same file size, permissions, timestamp, etc., its inode is different from one server to the next.

IIS 5.0 and 6.0 have a similar issue with ETags. The format for ETags on IIS is Filetimestamp:ChangeNumber. A ChangeNumber is a counter used to track configuration changes to IIS. It’s unlikely that the ChangeNumber is the same across all IIS servers behind a web site.

The end result is ETags generated by Apache and IIS for the exact same component won’t match from one server to another. If the ETags don’t match, the user doesn’t receive the small, fast 304 response that ETags were designed for; instead, they’ll get a normal 200 response along with all the data for the component. If you host your web site on just one server, this isn’t a problem. But if you have multiple servers hosting your web site, and you’re using Apache or IIS with the default ETag configuration, your users are getting slower pages, your servers have a higher load, you’re consuming greater bandwidth, and proxies aren’t caching your content efficiently. Even if your components have a far future Expires header, a conditional GET request is still made whenever the user hits Reload or Refresh.

If you’re not taking advantage of the flexible validation model that ETags provide, it’s better to just remove the ETag altogether. The Last-Modified header validates based on the component’s timestamp. And removing the ETag reduces the size of the HTTP headers in both the response and subsequent requests. This Microsoft Support article describes how to remove ETags. In Apache, this is done by simply adding the following line to your Apache configuration file:

      FileETag none

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Make Ajax Cacheable

tag: content

One of the cited benefits of Ajax is that it provides instantaneous feedback to the user because it requests information asynchronously from the backend web server. However, using Ajax is no guarantee that the user won’t be twiddling his thumbs waiting for those asynchronous JavaScript and XML responses to return. In many applications, whether or not the user is kept waiting depends on how Ajax is used. For example, in a web-based email client the user will be kept waiting for the results of an Ajax request to find all the email messages that match their search criteria. It’s important to remember that “asynchronous” does not imply “instantaneous”.

To improve performance, it’s important to optimize these Ajax responses. The most important way to improve the performance of Ajax is to make the responses cacheable, as discussed in Add an Expires or a Cache-Control Header. Some of the other rules also apply to Ajax:

• Gzip Components
• Reduce DNS Lookups
• Minify JavaScript
• Avoid Redirects
• Configure ETags

Let’s look at an example. A Web 2.0 email client might use Ajax to download the user’s address book for autocompletion. If the user hasn’t modified her address book since the last time she used the email web app, the previous address book response could be read from cache if that Ajax response was made cacheable with a future Expires or Cache-Control header. The browser must be informed when to use a previously cached address book response versus requesting a new one. This could be done by adding a timestamp to the address book Ajax URL indicating the last time the user modified her address book, for example, &t=1190241612. If the address book hasn’t been modified since the last download, the timestamp will be the same and the address book will be read from the browser’s cache eliminating an extra HTTP roundtrip. If the user has modified her address book, the timestamp ensures the new URL doesn’t match the cached response, and the browser will request the updated address book entries.

Even though your Ajax responses are created dynamically, and might only be applicable to a single user, they can still be cached. Doing so will make your Web 2.0 apps faster.

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Flush the Buffer Early

tag: server

When users request a page, it can take anywhere from 200 to 500ms for the backend server to stitch together the HTML page. During this time, the browser is idle as it waits for the data to arrive. In PHP you have the function flush(). It allows you to send your partially ready HTML response to the browser so that the browser can start fetching components while your backend is busy with the rest of the HTML page. The benefit is mainly seen on busy backends or light frontends.

A good place to consider flushing is right after the HEAD because the HTML for the head is usually easier to produce and it allows you to include any CSS and JavaScript files for the browser to start fetching in parallel while the backend is still processing.

Example:

      ... <!-- css, js -->
    </head>
    <?php flush(); ?>
    <body>
      ... <!-- content -->

Yahoo! search pioneered research and real user testing to prove the benefits of using this technique.

Use GET for AJAX Requests

tag: server

The Yahoo! Mail team found that when using XMLHttpRequest, POST is implemented in the browsers as a two-step process: sending the headers first, then sending data. So it’s best to use GET, which only takes one TCP packet to send (unless you have a lot of cookies). The maximum URL length in IE is 2K, so if you send more than 2K data you might not be able to use GET.

An interesting side affect is that POST without actually posting any data behaves like GET. Based on the HTTP specs, GET is meant for retrieving information, so it makes sense (semantically) to use GET when you’re only requesting data, as opposed to sending data to be stored server-side.

Post-load Components

tag: content

You can take a closer look at your page and ask yourself: “What’s absolutely required in order to render the page initially?”. The rest of the content and components can wait.

JavaScript is an ideal candidate for splitting before and after the onload event. For example if you have JavaScript code and libraries that do drag and drop and animations, those can wait, because dragging elements on the page comes after the initial rendering. Other places to look for candidates for post-loading include hidden content (content that appears after a user action) and images below the fold.

Tools to help you out in your effort: YUI Image Loader allows you to delay images below the fold and the YUI Get utility is an easy way to include JS and CSS on the fly. For an example in the wild take a look at Yahoo! Home Page with Firebug’s Net Panel turned on.

It’s good when the performance goals are inline with other web development best practices. In this case, the idea of progressive enhancement tells us that JavaScript, when supported, can improve the user experience but you have to make sure the page works even without JavaScript. So after you’ve made sure the page works fine, you can enhance it with some post-loaded scripts that give you more bells and whistles such as drag and drop and animations.

Preload Components

tag: content

Preload may look like the opposite of post-load, but it actually has a different goal. By preloading components you can take advantage of the time the browser is idle and request components (like images, styles and scripts) you’ll need in the future. This way when the user visits the next page, you could have most of the components already in the cache and your page will load much faster for the user.

There are actually several types of preloading:

• Unconditional preload – as soon as onload fires, you go ahead and fetch some extra components. Check google.com for an example of how a sprite image is requested onload. This sprite image is not needed on the google.com homepage, but it is needed on the consecutive search result page.
• Conditional preload – based on a user action you make an educated guess where the user is headed next and preload accordingly. On search.yahoo.com you can see how some extra components are requested after you start typing in the input box.
• Anticipated preload – preload in advance before launching a redesign. It often happens after a redesign that you hear: “The new site is cool, but it’s slower than before”. Part of the problem could be that the users were visiting your old site with a full cache, but the new one is always an empty cache experience. You can mitigate this side effect by preloading some components before you even launched the redesign. Your old site can use the time the browser is idle and request images and scripts that will be used by the new site

Reduce the Number of DOM Elements

tag: content

A complex page means more bytes to download and it also means slower DOM access in JavaScript. It makes a difference if you loop through 500 or 5000 DOM elements on the page when you want to add an event handler for example.

A high number of DOM elements can be a symptom that there’s something that should be improved with the markup of the page without necessarily removing content. Are you using nested tables for layout purposes? Are you throwing in more <div>s only to fix layout issues? Maybe there’s a better and more semantically correct way to do your markup.

A great help with layouts are the YUI CSS utilities: grids.css can help you with the overall layout, fonts.css and reset.css can help you strip away the browser’s defaults formatting. This is a chance to start fresh and think about your markup, for example use <div>s only when it makes sense semantically, and not because it renders a new line.

The number of DOM elements is easy to test, just type in Firebug’s console:
document.getElementsByTagName('*').length

And how many DOM elements are too many? Check other similar pages that have good markup. For example the Yahoo! Home Page is a pretty busy page and still under 700 elements (HTML tags).

Split Components Across Domains

tag: content

Splitting components allows you to maximize parallel downloads. Make sure you’re using not more than 2-4 domains because of the DNS lookup penalty. For example, you can host your HTML and dynamic content on www.example.org and split static components between static1.example.org and static2.example.org

For more information check “Maximizing Parallel Downloads in the Carpool Lane” by Tenni Theurer and Patty Chi.

Minimize the Number of iframes

tag: content

Iframes allow an HTML document to be inserted in the parent document. It’s important to understand how iframes work so they can be used effectively.

<iframe> pros:

• Helps with slow third-party content like badges and ads
• Security sandbox
• Download scripts in parallel

<iframe> cons:

• Costly even if blank
• Blocks page onload
• Non-semantic

No 404s

tag: content

HTTP requests are expensive so making an HTTP request and getting a useless response (i.e. 404 Not Found) is totally unnecessary and will slow down the user experience without any benefit.

Some sites have helpful 404s “Did you mean X?”, which is great for the user experience but also wastes server resources (like database, etc). Particularly bad is when the link to an external JavaScript is wrong and the result is a 404. First, this download will block parallel downloads. Next the browser may try to parse the 404 response body as if it were JavaScript code, trying to find something usable in it.

Reduce Cookie Size

tag: cookie

HTTP cookies are used for a variety of reasons such as authentication and personalization. Information about cookies is exchanged in the HTTP headers between web servers and browsers. It’s important to keep the size of cookies as low as possible to minimize the impact on the user’s response time.

For more information check “When the Cookie Crumbles” by Tenni Theurer and Patty Chi. The take-home of this research:

• Eliminate unnecessary cookies
• Keep cookie sizes as low as possible to minimize the impact on the user response time
• Be mindful of setting cookies at the appropriate domain level so other sub-domains are not affected
• Set an Expires date appropriately. An earlier Expires date or none removes the cookie sooner, improving the user response time

Use Cookie-free Domains for Components

tag: cookie

When the browser makes a request for a static image and sends cookies together with the request, the server doesn’t have any use for those cookies. So they only create network traffic for no good reason. You should make sure static components are requested with cookie-free requests. Create a subdomain and host all your static components there.

If your domain is www.example.org, you can host your static components on static.example.org. However, if you’ve already set cookies on the top-level domain example.org as opposed to www.example.org, then all the requests to static.example.org will include those cookies. In this case, you can buy a whole new domain, host your static components there, and keep this domain cookie-free. Yahoo! uses yimg.com, YouTube uses ytimg.com, Amazon uses images-amazon.com and so on.

Another benefit of hosting static components on a cookie-free domain is that some proxies might refuse to cache the components that are requested with cookies. On a related note, if you wonder if you should use example.org or www.example.org for your home page, consider the cookie impact. Omitting www leaves you no choice but to write cookies to *.example.org, so for performance reasons it’s best to use the www subdomain and write the cookies to that subdomain.

Minimize DOM Access

tag: javascript

Accessing DOM elements with JavaScript is slow so in order to have a more responsive page, you should:

• Cache references to accessed elements
• Update nodes “offline” and then add them to the tree
• Avoid fixing layout with JavaScript

For more information check the YUI theatre’s “High Performance Ajax Applications” by Julien Lecomte.

Develop Smart Event Handlers

tag: javascript

Sometimes pages feel less responsive because of too many event handlers attached to different elements of the DOM tree which are then executed too often. That’s why using event delegation is a good approach. If you have 10 buttons inside a div, attach only one event handler to the div wrapper, instead of one handler for each button. Events bubble up so you’ll be able to catch the event and figure out which button it originated from.

You also don’t need to wait for the onload event in order to start doing something with the DOM tree. Often all you need is the element you want to access to be available in the tree. You don’t have to wait for all images to be downloaded. DOMContentLoaded is the event you might consider using instead of onload, but until it’s available in all browsers, you can use the YUI Event utility, which has an onAvailable method.

For more information check the YUI theatre’s “High Performance Ajax Applications” by Julien Lecomte.

Choose <link> over @import

tag: css

One of the previous best practices states that CSS should be at the top in order to allow for progressive rendering.

In IE @import behaves the same as using <link> at the bottom of the page, so it’s best not to use it.

Avoid Filters

tag: css

The IE-proprietary AlphaImageLoader filter aims to fix a problem with semi-transparent true color PNGs in IE versions < 7. The problem with this filter is that it blocks rendering and freezes the browser while the image is being downloaded. It also increases memory consumption and is applied per element, not per image, so the problem is multiplied.

The best approach is to avoid AlphaImageLoader completely and use gracefully degrading PNG8 instead, which are fine in IE. If you absolutely need AlphaImageLoader, use the underscore hack _filter as to not penalize your IE7+ users.

Optimize Images

tag: images

After a designer is done with creating the images for your web page, there are still some things you can try before you FTP those images to your web server.

• You can check the GIFs and see if they are using a palette size corresponding to the number of colors in the image. Using imagemagick it’s easy to check using
  identify -verbose image.gif
  When you see an image useing 4 colors and a 256 color “slots” in the palette, there is room for improvement.
• Try converting GIFs to PNGs and see if there is a saving. More often than not, there is. Developers often hesitate to use PNGs due to the limited support in browsers, but this is now a thing of the past. The only real problem is alpha-transparency in true color PNGs, but then again, GIFs are not true color and don’t support variable transparency either. So anything a GIF can do, a palette PNG (PNG8) can do too (except for animations). This simple imagemagick command results in totally safe-to-use PNGs:
  convert image.gif image.png
  “All we are saying is: Give PiNG a Chance!”
• Run pngcrush (or any other PNG optimizer tool) on all your PNGs. Example:
  pngcrush image.png -rem alla -reduce -brute result.png
• Run jpegtran on all your JPEGs. This tool does lossless JPEG operations such as rotation and can also be used to optimize and remove comments and other useless information (such as EXIF information) from your images.
  jpegtran -copy none -optimize -perfect src.jpg dest.jpg

Optimize CSS Sprites

tag: images

• Arranging the images in the sprite horizontally as opposed to vertically usually results in a smaller file size.
• Combining similar colors in a sprite helps you keep the color count low, ideally under 256 colors so to fit in a PNG8.
• “Be mobile-friendly” and don’t leave big gaps between the images in a sprite. This doesn’t affect the file size as much but requires less memory for the user agent to decompress the image into a pixel map. 100×100 image is 10 thousand pixels, where 1000×1000 is 1 million pixels

Don’t Scale Images in HTML

tag: images

Don’t use a bigger image than you need just because you can set the width and height in HTML. If you need
<img width="100" height="100" src="mycat.jpg" alt="My Cat" />
then your image (mycat.jpg) should be 100×100px rather than a scaled down 500×500px image.

Make favicon.ico Small and Cacheable

tag: images

The favicon.ico is an image that stays in the root of your server. It’s a necessary evil because even if you don’t care about it the browser will still request it, so it’s better not to respond with a 404 Not Found. Also since it’s on the same server, cookies are sent every time it’s requested. This image also interferes with the download sequence, for example in IE when you request extra components in the onload, the favicon will be downloaded before these extra components.

So to mitigate the drawbacks of having a favicon.ico make sure:

• It’s small, preferably under 1K.
• Set Expires header with what you feel comfortable (since you cannot rename it if you decide to change it). You can probably safely set the Expires header a few months in the future. You can check the last modified date of your current favicon.ico to make an informed decision.

Imagemagick can help you create small favicons

Keep Components under 25K

tag: mobile

This restriction is related to the fact that iPhone won’t cache components bigger than 25K. Note that this is the uncompressed size. This is where minification is important because gzip alone may not be sufficient.

For more information check “Performance Research, Part 5: iPhone Cacheability – Making it Stick” by Wayne Shea and Tenni Theurer.

Pack Components into a Multipart Document

tag: mobile

Packing components into a multipart document is like an email with attachments, it helps you fetch several components with one HTTP request (remember: HTTP requests are expensive). When you use this technique, first check if the user agent supports it (iPhone does not).

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