Classic ASP
Classic ASP
Firebase Receive Server-Sent Events (text/event-stream)
See more Firebase Examples
Demonstrates how to start receiving server-sent events and update your JSON database with each event.Chilkat Classic ASP Downloads
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head>
<body>
<%
success = 0
' Demonstrates how to begin receiving server-sent events, and to update
' your JSON database for each event.
' This example requires the Chilkat API to have been previously unlocked.
' See Global Unlock Sample for sample code.
' This example assumes a JWT authentication token, if required, has been previously obtained.
' See Get Firebase Access Token from JSON Service Account Private Key for sample code.
' Load the previously obtained Firebase access token into a string.
set fac = Server.CreateObject("Chilkat.FileAccess")
accessToken = fac.ReadEntireTextFile("qa_data/tokens/firebaseToken.txt","utf-8")
If (fac.LastMethodSuccess = 0) Then
Response.Write "<pre>" & Server.HTMLEncode( fac.LastErrorText) & "</pre>"
Response.End
End If
set rest = Server.CreateObject("Chilkat.Rest")
' Make the initial connection (without sending a request yet).
' Once connected, any number of requests may be sent. It is not necessary to explicitly
' call Connect before each request.
success = rest.Connect("chilkat.firebaseio.com",443,1,1)
If (success = 0) Then
Response.Write "<pre>" & Server.HTMLEncode( rest.LastErrorText) & "</pre>"
Response.End
End If
set authGoogle = Server.CreateObject("Chilkat.AuthGoogle")
authGoogle.AccessToken = accessToken
success = rest.SetAuthGoogle(authGoogle)
success = rest.AddHeader("Accept","text/event-stream")
success = rest.AddHeader("Cache-Control","no-cache")
responseBody = rest.FullRequestNoBody("GET","/.json")
' A 307 redirect response is expected.
If (rest.ResponseStatusCode <> 307) Then
Response.Write "<pre>" & Server.HTMLEncode( "Unexpected response code: " & rest.ResponseStatusCode) & "</pre>"
Response.Write "<pre>" & Server.HTMLEncode( responseBody) & "</pre>"
Response.Write "<pre>" & Server.HTMLEncode( "Failed.") & "</pre>"
Response.End
End If
' Get the redirect URL
urlStr = rest.LastRedirectUrl
set url = Server.CreateObject("Chilkat.Url")
success = url.ParseUrl(urlStr)
Response.Write "<pre>" & Server.HTMLEncode( "redirect URL domain: " & url.Host) & "</pre>"
Response.Write "<pre>" & Server.HTMLEncode( "redirect URL path: " & url.Path) & "</pre>"
Response.Write "<pre>" & Server.HTMLEncode( "redirect URL query params: " & url.Query) & "</pre>"
Response.Write "<pre>" & Server.HTMLEncode( "redirect URL path with query params: " & url.PathWithQueryParams) & "</pre>"
' Our text/event-stream will be obtained from the redirect URL...
set rest2 = Server.CreateObject("Chilkat.Rest")
success = rest2.Connect(url.Host,443,1,1)
If (success <> 1) Then
Response.Write "<pre>" & Server.HTMLEncode( rest2.LastErrorText) & "</pre>"
Response.End
End If
success = rest2.AddHeader("Accept","text/event-stream")
success = rest2.AddHeader("Cache-Control","no-cache")
' Add the redirect query params to the request
success = rest2.AddQueryParams(url.Query)
' In our case, we don't actually need the auth query param,
' so remove it.
success = rest2.RemoveQueryParam("auth")
' Send the request. (We are only sending the request here.
' We are not yet getting the response because the response
' will be a text/event-stream.)
success = rest2.SendReqNoBody("GET",url.Path)
If (success <> 1) Then
Response.Write "<pre>" & Server.HTMLEncode( rest2.LastErrorText) & "</pre>"
Response.End
End If
' Read the response header.
' We want to first get the response header to see if it's a successful
' response status code. If not, then the response will not be a text/event-stream
' and we should read the response body normally.
responseStatusCode = rest2.ReadResponseHeader()
If (responseStatusCode < 0) Then
Response.Write "<pre>" & Server.HTMLEncode( rest2.LastErrorText) & "</pre>"
Response.End
End If
' If successful, a 200 response code is expected.
' If the reponse code is not 200, then read the response body and fail..
If (responseStatusCode <> 200) Then
Response.Write "<pre>" & Server.HTMLEncode( "Response Code: " & responseStatusCode) & "</pre>"
Response.Write "<pre>" & Server.HTMLEncode( "Response Status Text: " & rest2.ResponseStatusText) & "</pre>"
Response.Write "<pre>" & Server.HTMLEncode( "Response Header: " & rest2.ResponseHeader) & "</pre>"
responseBody = rest2.ReadRespBodyString()
If (rest2.LastMethodSuccess = 1) Then
Response.Write "<pre>" & Server.HTMLEncode( "Error Response Body: " & responseBody) & "</pre>"
End If
Response.Write "<pre>" & Server.HTMLEncode( "Failed.") & "</pre>"
Response.End
End If
' For this example, our JSON database will be empty at the beginning.
' The incoming events (put and patch) will be applied to this database.
set jsonDb = Server.CreateObject("Chilkat.JsonObject")
' Make sure to set the JSON path delimiter to "/". The default is "." and this
' is not compatible with Firebase paths.
jsonDb.DelimiterChar = "/"
' At this point, we've received the response header. Now it's time to begin
' receiving the event stream. We'll start a background thread to read the
' stream. (Our main application (foreground) thread can cancel it at any time.)
' While receiving in the background thread, our foreground thread can read the stream
' as it desires..
set eventStream = Server.CreateObject("Chilkat.Stream")
' This sse object will be used as a helper to parse the server-sent event stream.
set sse = Server.CreateObject("Chilkat.ServerSentEvent")
' task is a Chilkat.Task
Set task = rest2.ReadRespBodyStreamAsync(eventStream,1)
success = task.Run()
' For this example, we'll just read a few events, and then cancel the
' async task.
count = 0
Do While (count < 3) And (task.Finished = 0)
' Get the next event, which is a series of text lines ending with
' a blank line.
' Note: This method blocks the calling thread until a message arrives.
' a program might instead periodically check the availability of
' data via the stream's DataAvailable property, and then do the read.
' An alternative to writing a while loop to read the event stream
' would be to setup some sort of timer event in your program (using whatever timer functionality
' is provided in a programming language/environment), to periodically check the eventStream's
' DataAvailable property and consume the incoming event.
eventStr = eventStream.ReadUntilMatch(vbCrLf & vbCrLf)
If (eventStream.LastMethodSuccess <> 1) Then
Response.Write "<pre>" & Server.HTMLEncode( eventStream.LastErrorText) & "</pre>"
' Force the loop to exit by setting the count to a high number.
count = 99999
Else
Response.Write "<pre>" & Server.HTMLEncode( "Event: [" & eventStr & "]") & "</pre>"
' We have an event. Let's update our local copy of the JSON database.
success = sse.LoadEvent(eventStr)
If (success <> 1) Then
Response.Write "<pre>" & Server.HTMLEncode( "Failed to load sse event: " & eventStr) & "</pre>"
Else
' Now we can easily access the event name and data, and apply it to our JSON database:
success = jsonDb.FirebaseApplyEvent(sse.EventName,sse.Data)
If (success <> 1) Then
Response.Write "<pre>" & Server.HTMLEncode( "Failed to apply event: " & sse.EventName & ": " & sse.Data) & "</pre>"
Else
Response.Write "<pre>" & Server.HTMLEncode( "Successfully applied event: " & sse.EventName & ": " & sse.Data) & "</pre>"
End If
End If
End If
count = count + 1
Loop
' Make sure the background task is cancelled if still running.
success = task.Cancel()
' Examine the JSON database after applying events..
jsonDb.EmitCompact = 0
Response.Write "<pre>" & Server.HTMLEncode( "----") & "</pre>"
Response.Write "<pre>" & Server.HTMLEncode( jsonDb.Emit()) & "</pre>"
%>
</body>
</html>