To display the current time in a user-readable format, say Aug 24 2008 04:25 PM, the SimpleDateFormat class in Java can be used thus :


Timestamp currentTime = new Timestamp(System.currentTimeMillis());
SimpleDateFormat sdf = new SimpleDateFormat("MMM dd yyyy hh:mm a");
String currentTimeFormatted = sdf.format(currentTime);
System.out.println(currentTimeFormatted);


On the other hand, this can be easily achieved in a SQL query (MS SQL) :

SELECT CONVERT(CHAR, GETDATE()) AS 'FormattedDate';

The next one is another useful query (again, MS SQL) that I came across recently (for which I am yet to figure out an equivalent Java code !!) - this truncates the time part of the timestamp and makes it 00:00:00.000 in order to represent the midnight of that particular day.

SELECT CAST( FLOOR( CAST(GETDATE() AS FLOAT ) ) AS DATETIME) AS 'DateTimeAtMidnight';


Alas for my Saturday mornings, but it is a matter of pride and I do value the practice.

In case you've missed out on any of the backdated entries and would like to catch up, feel free to use the calendar to preview the titles of the last month's entries, or use the following list.

Anti-Papist Ironies --- In this rare detour into personal religion, a response to anti-Catholic criticisms.
Working Guys and Dolls --- Equal opportunity employment doesn't mean equal retention and turnover.
Be Cool to the Camera Guy, Part Two --- Unsatisfactorily answering the age-old question: Isn't teaching the hardest job, ever?
Blame Expendable Women --- Neo-conservative leaders aren't sexist --- they know women can defend themselves.
Be Cool to the Camera Guy, Part One --- You accomplish nothing by being rude to the service industry's peons.
Good Thing Copland’s Dead --- If you've never heard the Lincoln Portrait, be glad.
Three-Drill Monte for Oil --- Stephen Colbert lampoons both ridiculous sides of the energy debate.
Alma Mater of Siblings --- Younger sister follows in steps of older brother, but it could just be a coincidence.
My Car's Name is Helen --- My very special relationship breaks down.

Will I be back on track next week, even though I'll be working four days next week, the school photography season is only just picking up and I have two weekly band rehearsals I have to worry about? Signs point to yes.

See you all tomorrow.


import datetime, time

stamp=datetime.datetime.fromtimestamp(time.time()).strftime("%Y-%m-%d %H:%M:%S")


As I looked at the photo at this website, I wondered what it must be like for birds who are required according to human work definition to get up early and "get the worm." (do birds in Mexico arise early to get the worm from tequila bottles...?) I wondered if birds realized the significance in the difference between that part of the day and let's say a few hours later. I feel that they must awake early because nature directs them to, but if they had the choice like some lazy humans do, to arise later than expected and catch a different part of the day first, would they realize at some point, the beauty they have been missing as I did today?

I have for the most part been a night owl, preferring late night hours versus arising at 6 a.m. only to have coffee and venture to a 9-5. I have worked overnight hours several times and have found my work to be more productive... and when I went to school, I always arose late for class... and when I went to class in college, I always performed better in later classes than those 7 a.m. lectures.

Night hours have always seemed special to me and more fitting. Maybe its because there's less activity going on. Or maybe cause there's less people around. Or maybe because its less sunny and therefore generally cooler than the daytime heat. Or maybe it has to do with energy and that there's less chaotic energy in the air to disrupt my overly sensitive senses.

But lately, being unemployed, I find myself awaking around 7 and going to bed around 11. Its a weird sensation waking up early and I have grown to like it. I feel like I am more part of the real world, even though I am not working. I feel as if I am doing what is correct by nature. And when I do get up early, I go outside with the doggie and admire the way the day is at that time. If I was still enjoying cigars and coffee, you can be sure I would have one or both of those things during these moments. The weird thing is that I am not even tired anymore at 7.am. I do get tired around 9 for some reason, but at 7, where I used to be groggy, its as if I was supposed to be up and I don't even need any stimulants to make me feel more awake as most people seem to require. If I was working, this feeling would be ideal.

Anyway, I just wanted to share my appreciation for the a.m. with you. I wonder if there other night owls who have gone through the same thing... you know a transfer from a night owl to an early bird. Is it part of getting older? Is it part of my constant urge to eat? Is it my subconscious trying to kick my lazy conscience in to gear and get me motivated? Is it just my senses connecting to the part of the day that just seems to glisten with natural beauty? Not sure, but its nearing 9, and I must get in a nap...

owl photo borrowed from www.annapodris.com

Para isso usaremos a função mktime(), que retorna um timestamp, ou seja, o numero de segundos desde que a época UNIX começou(1 de janeiro de 1970).

Para resolver este problema vamos criar uma função que recebe duas datas e retorna a quantidade tempo percorrido entre elas:

// Determinando um intervalo entre duas datas
// formato: dd/mm/aaaa

function calculaIntervalo($data1,$data2=''){
	// se data2 for omitida, o calculo sera feito ate a data atual
	$data2 = $data2=='' ? date("d/m/Y",mktime()) : $data2;

	// separa as datas em dia,mes e ano
	list($dia1,$mes1,$ano1) = explode("/",$data1);
	list($dia2,$mes2,$ano2) = explode("/",$data2);

	// so lembrando que o padrao eh MM/DD/AAAA
	$timestamp1 = mktime(0,0,0,$mes1,$dia1,$ano1);
	$timestamp2 = mktime(0,0,0,$mes2,$dia2,$ano2);

	// calcula a diferenca em timestamp
	$diferenca = ($timestamp1 > $timestamp2) ? ($timestamp1 - $timestamp2) : ($timestamp2 - $timestamp1);

	// retorna o calculo em anos, meses e dias
	return (date("Y",$diferenca)-1970)." anos,".(date("m",$diferenca)-1)." meses e ".(date("d",$diferenca)-1)." dias";

}

1. timestamp != date or time

The timestamp data type in SQL server is not a date or time. In fact, it's not even related. It's a binary field that increments each time a row is changed. This means it's really just what it's synonym - rowversion suggests it is. A row version. If you want to use it, it maps to the .Net SqlBinary type. More on this later...

2. Error severity level

I found getting a description of the error severity levels notoriously difficult. Using the SQL RaiseError function with error level 1 causes the error to be swallowed as informational within the action, rather than raising as an exception to the framework. This can be quite frustrating at first but I found a good guide to error handling in SQL server here. This guide gave me just about everything I needed to know and I highly recommend it.

3. timestamp == SqlBinary

As mentioned, the timestamp type maps to the SqlBinary type (see here for a compleye type mapping list). If you don't want to pass the Sql type around all over the place, use the .Value property to obtain the byte array that makes up the timestamp and keep it in your object instead. You could make this field read only as well, but considering most of the time if the user changes this field (unless they know exactly how many row changes between now and their update reaching the database) their change will cause the update to be rejected anyway.

You'll notice in the MSDN list timestamp doesn't map to a specific .Net framework type. Use rowversion synoym instead which maps to byte[]. I've read a few blogs and articles that recommend using rowversion instead, so that if the concepts diverge in future editions behaviour remains consistent. I think this is a good idea, and that the mappings chart provides a solid reason to trust these recommendations.

So there they are, a few little hints that I picked up on my way to implementing some kind of concurrency control through row versioning.

Some say midnight, others say 7 a.m. and many say its when you wake up after a sleep, but what truly defines tomorrow.

Let me give you an example of the confusion. Let's say I have been up till 5 a.m., partying, writing, watching infomercials... whatever it is I have been doing, I am still up at 5 a.m. doing it. Now technically it is after midnight and therefore by definition, it is already the next day ( I mean the time machine inside this computer already has changed the date.) But at midnight, it doesn't necessarily feel like the next day, unless of course its new year's eve 1999 and it feels like the next millenia. But the clock reads Jan.1 2000 so technically, it is tomorrow.

But I continue to stay up until 5 a.m. When I awake once again at 11, I begin my routine for the next day and it is therefore at that moment that I can say for myself it is tomorrow. But the dilema worsens when I stay up until 11 and begin my day without ever going to sleep. Now of course by definition, it was already tomorrow at midnight, but using the "it is a new day after you wake up theory," then tomorrow is still today... but since the date has changed in the computer, then technically this tomorrow is actually still yesterday, right? Do you follow me with this?

Many people would say that the next day begins with a new sunrise, but what if the sun rises around 8:30 somewhere, and you are already well slept, and awake by 6 a.m. For you, the past day is already behind you, and you have begun your next day even before there is light to illuminate your day... but is that tomorrow?

I raise this question, today, as I have gotten into the habbit of defining the next day as 7 a.m. I am not sure how this got started, but I think I can refer to the film GROUNDHOGS DAY starring Bill Murray and Andy McDowell when everyday in Bill Murray's world, when the clock reached 7 a.m., he would wake up in the same day he just fell asleep on. But the one time he moved forward into the next day, was when he stayed up past that 7 a.m. time.

But today, I awoke just before 6 a.m. and created this blog. Now by my standards that I have grown accustomed to, it hasn't even become the next day yet... it is still yesterday because its before 7 a.m., but I have already slept and its past the sunrise so last night has come and gone. Man am I confused. Its like PURGATORY FOR TIME.

Perhaps tomorrow, I will have a better understanding of today, or maybe later today, I ill better understand tomorrow. Either way, enjoy your tomorrow today!

One strategy is to make a timelapse movie of the synapses.  In mice, this can be accomplished by installing a cortical window on the skull, and imaging the changes in structure of GFP labelled neurons. However, this is technically demanding, only works with sparsely labeled neurons, and accesses only a small subset of the neurons which may be involved in the learning process.  

Ideally, one could have a tag which can discriminate between synapses existing before learning takes place, and new ones generated after learning has occurred. Whole brain regions could then be examined at a single timepoint to see where new synapses were added. In a large step towards that goal, Michael Lin et. al, from the lab of Roger Tsien, report TimeSTAMP, a genetic label for newly synthesized protein.

The authors engineered the NS3 protease from the hepatitis C virus (HCV) to cleave itself at just the right pace. They then fuse tags (fluorescent proteins or epitopes) before and after the cleavage site. This fusion is then tagged to the end of a protein of interest. Shortly after synthesis, the protein cleaves off the C-terminal tag, but the N-terminal is left on. This cleavage is inhibitable by a variety of small molecule blockers. In the presence of the blocker, the C-terminal tag stays on. By controlling when drug is applied, they can selectively label a set of proteins of a particular age with the tags.

The choice of NS3 protease was very clever, as it is a favorite drug target of biotech and pharma companies.  Many inhibitors of this protein have been synthesized, exhaustively characterized in vitro and in clinical trials. This work is a great example of the standard research flow going in reverse; a basic-science project from an academic lab is actually benefitting from pharma company research. Stability, bioavailablity and toxicity have already been worked out.  One of the biggest impediments is actually getting ahold of these compounds. Companies with their survival hanging on the clinical success of a single small molecule inhibitor are understandably reluctant to hand out stocks for academic research. Note the roller coaster stock price of Vertex following results of its NS3 protease inhibitor (VX-950) trials. 

The authors use PSD-95 tagged to TimeSTAMP as a proxy marker of synaptic age. In neuronal culture, they show that newly synthesized synapses have a C-tag / N-tag ratio of about twice as large as old synapses.

They extend the technique to whole fruit fly brains, showing a very heterogeneous distribution of CaMKII synthesis across Kenyon cells in different areas of the mushroom body.

So far TimeSTAMP has not been shown to work in mice. Mice were not included in the paper due to the long generation time for transgenics. Given the good signal to noise and the large number of possible inhibitor molecules, I think this technique could be quite powerful in mammalian systems. It's big advantage would be to label large populations of neurons or synapses in diverse brain regions, including those inaccessible to two-photon microscopy. TimeSTAMP's success in labeling new synapses in the intact brain will be dependent on finding a protein to tag at the synapse with low turnover over the course of a learning experiment. Though PSD-95 appears to be a reasonable marker in culture, others have shown a higher rate of turnover in vivo, making in unsuitable for a synaptic marker. 

Now for my gripe. I've used strongly typed datatables in past projects and with some manipulation, you can get the datatable to treat the timestamp column as a bitint (Int64). Why does this matter? Because I've used it for some simple version tracking in the past, and this requires I perform range checking on these versions. A simplified explanation:

-Use the largest timestamp in my cached table
-Query the database table for any timestamps larger than this one
-Retrieve these new or updated items to be merged back into the original dataset

This normally is not useful for 2 or N tier apps, but in my instance I am transferring data over the net via a webservice so would like to only retrieve the new or changed records to the client.

Gripe time: why are these columns Binary? The only way I was historically able to query on them is to force sql server to cast them as a bigint, through some magic in the typed datatable. But now Im using Linq as my data access layer. I love linq so far, but I have tried every trick I can think of and it will not make this work- Linq will always fail with a illegal cast type error when it attempts to load the record.

So, whyt exactly are these binary? Wouldnt it be much easier to make use of rowversion and timestamps if they were represented as a real datatype like int64/bigint? I know I wouldnt have wasted half a day yesterday on this if this were the case.

So now it looks like Ill switch to using a datetime column that I hope is udpated with every edit or insert. Should work ok, but not my preference.

Il processo è simile sia per la voce che per il video, per cui la seguente descrizione generale è valida a grandi linee per entrambi i flussi:

1. Il flusso di bit in uscita dal codificatore, ad intervalli temporali regolari ed equispaziati, viene suddiviso in “pezzi”, ossia blocchi di bit che possono avere in alcuni casi dimensione variabile. Ad ogni pezzo è assegnato un timestamp, ossia un’etichetta temporale che indica l’istante di generazione alla sorgente.
2. Ciascun pezzo viene incapsulato in un pacchetto per il trasporto in rete, tramite l’aggiunta di un header contenente informazioni come istante di generazione o timestamp (ricavabile dal timestamp inserito al passo 1), numero di sequenza progressivo ed altre informazioni. Il pacchetto risultante è formato quindi dall’header e dal payload, quest’ultimo consistente nell’informazione utile (ossia il pezzo di audio o di video).
3. Può essere necessario in alcuni casi eseguire la frammentazione di un pezzo in più pezzi di dimensione più piccola, dando luogo ad altrettanti pacchetti, i quali saranno in tal caso caratterizzati dallo stesso timestamp ma da numeri di sequenza diversi.
4. Il pacchetto generato al passo 2 (ed eventualmente 3) ha tutte le informazioni necessarie, dal punto di vista dell’applicazione, per essere trasportato in rete.

Al lato ricevente dell’applicazione saranno eseguiti dei passaggi complementari in ordine inverso, ossia l’eventuale riassemblaggio nel caso di frammentazione, il de-incapsulamento e l’estrazione dell’informazione utile dai pacchetti.

I passaggi successivi ai passi 1-4 saranno quelli di incapsulare i pacchetti generati al passo 2 (ed eventualmente 3) in ulteriori pacchetti per fornire ad esempio informazioni utili per il supporto al controllo d’errore, all’indirizzamento, e così via.

Riferimenti

Tesi di laurea in Ingegneria Elettronica di Antonio Mancosu, A.A. 2005/2006: “Controllo del ritardo di playout nelle comunicazioni audio-video su reti a pacchetti”.

Antonio Mancosu

[sourcecode language='php']class Corpus extends AppModel {
    function afterSave($created) {
        if($this->id && $created) {
            $data = $this->read();
            $data[$this->name]["created"] = date("Y-m-d H:i:s");
            $this->save($data);
        }
    }
}[/sourcecode]

เวลาสั่ง save จาก controller, afterSave ก็จะถูกเรียกแล้วก็ไปแก้ column: created ให้เป็นเวลาปัจจุบัน. ถ้า row นั้นถูกสร้างขึ้นใหม่ (ตรวจสอบได้จาก $created).

update #1: แต่จะให้ดีใช้ beforeSave ดีกว่า. จะได้ save ครั้งเดียวไปเลย (ตาม comment ของ พี่ป๊อก) แล้วก็ดูเป็นธรรมชาติดีด้วย :-).

[sourcecode language='php']class Corpus extends AppModel {
function beforeSave() {
$data[$this->name]["created"] = date("Y-m-d H:i:s");
return true;
}
}[/sourcecode]

แต่ถ้า edit แต่ไม่ได้ create corpus ก็คงต้องวิธีมาตรวจสอบเอา.

update #2: ลองดูอีกนิด จริงๆ แล้วไม่ต้องใช้ before/after save เลย. CakePHP ทำ timestamp ให้เองแบบที่ต้องการเลย โดยที่ไม่ต้องทำอะไร ... แป่ว

Когда вы уже написали запись, обратите внимание на правую колонку и найдите там статус публикации (‘Publish Status’).

Нажмите ссылку Edit, расположенную рядом со словами «Опубликовать немедленно» (Publish Immediately) чтобы получить доступ к дате и времени публикации.

Затем введите дату и время когда вы хотите, чтобы запись появилась в вашем блоге. Потом вернитесь к записи и нажмите Publish. Ваша запись будет сохранена и появится в блоге в указанное время.

Вы можете «публиковать в будущем» столько записей, сколько пожелаете. Также вы можете изменять дату и время публикации для любой неопубликованной записи.

Еще раз.

Обычно когда вы нажимаете кнопку «Publish», запись, которую вы написали, публикуется немедленно. Однако, иногда бывает желательно изменить естественный порядок вещей.

Публикуем в прошлом

Нажмите Edit в статусе публикации (Publish Status area) и поменяйте дату и время на более ранние. Нажмите Publish. Запись будет опубликована немедленно, но она окажется где-то в середине вашего блога, не в самом начале. Она будет датирована датой и временем, которые вы указали перед публикацией.

Публикуем в будущем

Нажмите Edit в статусе публикации и выставьте дату и время в будущем. Нажмите Publish. Ваша запись не появится в блоге до тех пор, пока не наступит тот момент времени, который вы указали. По наступлению времени, указанного при публикации, запись будет опубликована автоматически.

Источники:

• http://faq.wordpress.com/2006/05/31/can-i-schedule-a-post/
• http://faq.wordpress.com/2006/10/23/post-options-post-timestamp/

My query, other than "What the hell are you doing up at 0330?", is that the message was time-stamped at 0331. The time displayed upon my 'phone, however was 0330 (a minute earlier). The clear implication is that messages are either time-stamped by the sender's mobile 'phone, or centrally by the service provider.

A time-stamp via the service provider (network), in my case 1-2-Call, seems the logical solution, but what if the sender and receiver subscribe to different networks? The other big provider in Thailand is D-Thai. Would the time-stamp be from the sender's service provider, or the receiver's provider?

Or do the networks simply not bother? Is the time-stamp based solely on the sender's phone?

Then, the pin will be located below the life ring/preserver thing, and next to the Lifeguard chair. It is an Aqua Grabber pin.

There is one new background in the Sport Shop:

Sports Shop Secrets:

 

In particolare dobbiamo elaborare delle statistiche durante un arco di tempo prefissato, ma i databases di SourceForge usano il timestamp in secondi per il tipo di dato date (ovvero la data). Quindi a noi serviva convertire il numero in un formato più comprensibile e facilmente gestibile anche con un foglio di calcolo (e badate bene che non ho detto excel :D ). Mi serviva quindi un programmino semplice e veloce per fare questa conversione ed ho subito pensato di usare Java dato che sapevo già quali metodi usare senza bisogno di googlare o cercare nelle API. ;)

La prima versione da me scritta consisteva in una semplice classe java che convertiva un solo timestamp alla volta (per esempio, il timestamp in secondi per la data di oggi vale circa 1204069465). Quindi era necessario uno script in bash + awk per iterare la funzione.

[sourcecode language='java']
import java.util.Calendar;

public class DataConverter {

public static void main(String[] args) {
long timestamp;
Calendar cal;
int d, m, y;

timestamp = Long.valueOf(args[0])*1000;
cal = Calendar.getInstance();
cal.setTimeInMillis(timestamp);

m = cal.get(Calendar.MONTH)+1;
d = cal.get(Calendar.DAY_OF_MONTH);
y = cal.get(Calendar.YEAR);
System.out.println(d + "/" + m + "/" + y);
}
}[/sourcecode]

paso@casa:~/polimi/tesi/prove$ time ./convertiDate.sh | sh > dateOutput.txt
 
real 18m10.902s
user 9m37.256s
sys 2m49.275s
paso@casa:~/polimi/tesi/prove$

troppo lento! più di 18 minuti 8O su un P4 da 3.2ghz, mica su un commodore 16 :D

È chiaro che si tratta di una programma fatto in fretta e furia e quindi per niente adatto su grandi numeri. Il collo di bottiglia è nella continua invocazione dell'intera classe java e non di solo una sua parte (tipo un sigolo metodo o un insieme ridotto di istruzioni), e quindi la continua riallocazione delle risorse (che vengono distrutte ogni volta che termina le istruzioni) necessarie per la sua esecuzione porta via i cicli di CPU poiché caricare i dati è decisamente più lento che eseguirli.

Nella prossima puntata vedremo come ottimizzare il codice utilizzando un solo linguaggio (Java) per fare tutto quello che ci serve.

PS: non so come mi sia venuto in mente di fare questo post così tecnico però mi piaceva e ci tenevo, magari può sempre servire a qualcuno, in fin dei conti i blog sono fatti per essere utili anche agli altri, altrimenti mi tenevo un diario segreto e personale nel mio comodino e buonanotte al secchio :)

Um exemplo simples de como calcular a diferença entre 2 datas utilizando o php, como bem sabemos um dia possui 24 horas que equivale a (24 * 60  * 60)  igual á 86400.

A função mktime recebe os argumentos (hora, minuto, segundos, mes, dia, ano).

<?php
#setando a primeira data  10/01/2008
$dia1 = mktime(0,0,0,01,10,2008);
#setando segunda data 10/02/2008
$dia2 = mktime(0,0,0,02,10,2008);  
#armazenando o valor da subtracao das datas
$d3 = ($dia2-$dia1);
#usando o roud para arrendondar os valores
#converter o tempo em dias
$dias = round(($d3/60/60/24));
#converter o tempo em horas
$hrs = round(($d3/60/60));
#converter o tempo em minutos
$mins = round(($d3/60));
#exibindo  dias | repudizira na tela 31
echo $dias."<br>";
#exibindo  horas | repudizira na tela 744
echo $hrs."<br>";
#exibindo  minutos | repudizira na tela 44640
echo $mins."<br>";
?>

Importante lembrar que acima hrs é o total de horas entre as duas datas e o mesmo para minutos.

Para tornar o exemplo útil você precisa setar de forma dinâmica os valores para $dia1 e $dia2, como exemplo imagine que seu sistema grava a data (mktime) de um post e faça o calculo do (diaAtual - diadoPost).

Dica:

Para passar para o formato comum uma data em mktime() use o date como abaixo:
echo date('d/m/Y',$dia2);

Até logo,

and...(again, we have Disney's advertising, which New Horizon Interactive DID NOT do)

The 'Save the Migrator Project' has begun at the Beach:

The new Rowboat pin is in the Lighthouse.

New Catalog!!!

Click on the rainbow pin in the new catalog on the admiral jacket to get green goggles.

Click on the Russian Hat for the Red Viking Helmet.

Do this 4 times to get the Blue Viking Helmet.

There are four new backgrounds for your player cards.

Rockhopper has once again left Club Penguin in his rowboat, look at the telescope to see him.

There is also a new Club Penguin poll out on the homepage:

Q: What's your favorite part about Rockhopper's visit this time?

Possible Answers:

a) Pirate Parades!

b) Free life jackets!

c) Visiting Yarr!

d) Just glad that he's okay.

e) Who's Rockhopper?

My Answer: Pirate Parades, and Visiting Yarr! (I always love free stuff, but the life jackets in my opinion were ugly this time around, so I didn't vote for that.

Voting Percentages so far:

a) 19%

b) 19%

c) 8%

d) 45%

e) 9%

Have a great Valentine's Day!

Your Penguin,

MrsHollywood

Remember to click "home" to see all of the more recent posts.

Your Penguin,

MrsHollywood

Proof of the existence of a signed document at a given time can be demonstrated by having a time stamp of the document signature issued by a trusted timestamp authority (TSA). A TSA is an entity that can demonstrate that it maintains its clock against a recognized time source such as NIST in the US. There are also standards for trusted time stamps such as RFC 3161 and ANSI X9.95, and a number of vendors that provide this service.

The basic process for obtaining a trusted time stamp is this:
The requesting party generates a hash or digital signature (only hashes may be signed in RFC 3161 compliant signatures) of the signed document and sends this value to the TSA. The TSA attaches a time stamp token to the hash, then digitally signs it with the TSA's certificate. The requesting party validates the time stamp token and then associates this token with the signed document. This establishes that the signed document existed at the time of the time stamp. It does this without the TSA being aware of the conents of the digital document being signed, thus preserving the confidentiality of the signed document.

There are several ways of generating a time stamp token. RFC 3161 requires support of a time stamp token that contains the time as Zulu time, specified to the second, or better. It also requires that the TSA include a unique serial number with every timestamp issued so that the TSA name and token serial number define a unique time stamp.

Some other methods of generating timestamps rely on "document chaining" which includes a piece of the previous timestamp with each certificate thus establishing the validity of the time. Other methods combine this with using a single timestamp for a given interval of time so that many documents receive the same timestamp, and it is calculated as function of all of these documents. Should this timestamp be challenged several other document authors could be used as witnesses! An interesting survey of timestamping methods by Michael de Mare can be found here.

Some other methods proposed use transient keys, meaning the key used for signing the document hash is a function of the time. Generation of "trusted time stamps" is an area of significant activity, and many vendors will emphasize the advantages of their (often proprietary) methods.

Usage of a trusted time stamp is necessary for increasing the reliability of an electronic signature in a document. For many documents an institution may rely on its own time server for a TSA - this is legitimate as long as the institution is able to document its timekeeping policies and demonstrate their reliability in the event that the time stamps are challenged.

With many vendors pushing their own methods for time stamping and the significant complexity that can be attached to the topic it is easy to get confused. However the question that a relying party should ask is "How good do they have to be?" There are many ways of legally establishing the time of the occurence of an event. Just insure that you can justify yours!

Here are the pics:

And...

Your Penguin,

MrsHollywood

Also, I was talking about how you pour coffee with the coffee shop uniform on, and so here it is. You only pour one cup of coffee though, and then your penguin just stands there with the coffee cup. You have to move to another spot, and dance again to pour another cup.

(This is me holding the coffee cup, after pouring it with that black thing. The coffee cup is not part of the apron, it's a coffee cup, not part of the apron. The apron is just plain green.)

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Your Penguin,

MrsHollywood