Este tópico descreve as diferenças entre o modo HTTP tradicional e o modo server-sent events (SSE). No modo HTTP tradicional, cada solicitação pode levar mais tempo para ser concluída e apenas um pacote de dados é retornado por solicitação. Com o SSE, vários eventos podem ser transmitidos do servidor para o cliente em tempo real quando novos dados estiverem disponíveis. Em comparação, o modo SSE é particularmente adequado para cenários que envolvem atualizações em tempo real, como geração dinâmica de texto.
Modo HTTP tradicional
No modo tradicional, cada solicitação resulta em um único pacote de resposta.
HTTP/1.1 200 OK
Server: AliyunOSS
Date: Mon, 07 Aug 2023 09:44:02 GMT
Content-Type: application/json;charset=UTF-8
Connection: close
Vary: Accept-Encoding
x-oss-request-id: 64D0BCDD88339E32330E2D1D
x-oss-server-time: 5865
Content-Encoding: gzip
{
"RequestID": "64D0BCDD88339E32330E2D1D",
"Output": {
"Text": "A Ghost, the Communist Ghost, haunts the European continent. In order to holy suppression of this ghost, all forces of the old Europe, including the Pope and the Czar, Metternich and Guizot, the radical party in France and the police in Germany, have united. Is there any opposition party that is not denounced by its governing enemies as a Communist? And is there any opposition party that does not use the charge of Communism as a weapon against more progressive oppositionists and its reactionary enemies? From this fact we can draw two conclusions: Communism has been recognized by all the forces of Europe as a power; it is now the turn of the Communists to make themselves known to the world, to state their views, their aims, their intentions, and to publish their own manifestos in order to refute the myth about the Communist ghost. For this purpose, delegates of the Communist parties of all countries assembled in London and adopted the following manifesto, which is published in English, French, German, Italian, Flemish and Danish.",
"FinishReason": "stop"
}
}Modo SSE
O modo SSE é limitado à comunicação unidirecional do servidor para o cliente. A interface EventSource faz parte do HTML Living Standard (anteriormente conhecido como HTML5).
Os dados transmitidos do servidor para o cliente no modo SSE são codificados usando UTF-8 e estão no formato de texto simples. Os dados são transmitidos como um fluxo de mensagens de evento separadas por dois caracteres de nova linha (\n\n). Cada mensagem de evento consiste em várias linhas formatadas como pares chave-valor [key]: value\n. As chaves opcionais são id, event e data. O campo data contém o conteúdo de uma mensagem.
O valor da chave data é um objeto JSON que contém os parâmetros de resposta.
Resposta de exemplo:
HTTP/1.1 200 OK
Server: AliyunOSS
Date: Mon, 07 Aug 2023 09:44:36 GMT
Content-Type: text/event-stream;charset=UTF-8
Transfer-Encoding: chunked
Connection: close
x-oss-request-id: 64D0BD0388339E30331D2D1D
x-oss-server-time: 761
id: 0
event: message
data: {"RequestId":"","Output":{"Text":"A Ghost,","FinishReason":"null"},"Usage":{"InputTokens":320,"OutputTokens":3}}
id: 1
event: message
data: {"RequestId":"","Output":{"Text":"A Ghost, the Communist Ghost, haunts the European","FinishReason":"null"},"Usage":{"InputTokens":320,"OutputTokens":11}}
id: 2
event: message
data: {"RequestId":"","Output":{"Text":"A Ghost, the Communist Ghost, haunts the European continent. In order to holy suppression of","FinishReason":"null"},"Usage":{"InputTokens":320,"OutputTokens":19}}
......
id: 27
event: Result
data: {"RequestId":"","Output":{"Text":"A Ghost, the Communist Ghost, haunts the European continent. In order to holy suppression of this ghost, all forces of the old Europe, including the Pope and the Czar, Metternich and Guizot, the radical party in France and the police in Germany, have united. Is there any opposition party that is not denounced by its governing enemies as a Communist? And is there any opposition party that does not use the charge of Communism as a weapon against more progressive oppositionists and its reactionary enemies? From this fact we can draw two conclusions: Communism has been recognized by all the forces of Europe as a power; it is now the turn of the Communists to make themselves known to the world, to state their views, their aims, their intentions, and to publish their own manifestos in order to refute the myth about the Communist ghost. For this purpose, delegates of the Communist parties of all countries assembled in London and adopted the following manifesto, which is published in English, French, German, Italian, Flemish and Danish.","FinishReason":"stop"},"Usage":{"InputTokens":320,"OutputTokens":212}}
Cada mensagem contém dados incrementais, indicando que os dados são progressivamente enriquecidos ou modificados como parte de cada solicitação.