I have a two part question.
First, what Dart command should I use to "start"
the VM service listening for requests, with possibly
giving it what host and port number to use.
I'm using Windows, and I don't need the Observatory possibly
interfering.
I'm currently trying to use this, after I CD into the project's directory:
dart --pause_isolates_on_start bicycle
And the second part of the question is, is it possible to verify
that the VM service is there and listening on whatever port?
I want to be able to send a request to the VM service,
from a WebSocket client, and get back a response.
After I give the above command, if I do a 'netstat'
it doesn't look like there is anything there listening.
And any attempts at trying to connect to the VM service get
a connection refused Exception, same as if I didn't even
try to start the VM service.
UPDATE:
I was looking at the intelliJ plugin code, to see how they did their connect,
and saw that they used "ws://localhost:8181/ws", I was trying to use
"ws://localhost:8181", and now it's finally getting past the handshake,
the server was returning "200 OK" instead of "101" before.
I'm assuming that I'm talking to the Observer at this point,
and not the VM service, I'm not sure, but at least I'm further along..
When it worked, I was using:
dart --enable-vm-service --pause_isolates_on_start bicycle.dart
Thanks!!
dart --help -v prints
--observe[=<port>[/<bind-address>]]
The observe flag is a convenience flag used to run a program with a
set of options which are often useful for debugging under Observatory.
These options are currently:
--enable-vm-service[=<port>[/<bind-address>]]
--pause-isolates-on-exit
--pause-isolates-on-unhandled-exceptions
--warn-on-pause-with-no-debugger
This set is subject to change.
Please see these options for further documentation.
It depends on what exactly you want to do, but as far as I know the Observatory just uses this service and if you don't access any of its features, it won't add additional load to the process.
There is a Dart client API https://pub.dartlang.org/packages/vm_service_client and a documentation about the protocol https://github.com/dart-lang/sdk/blob/master/runtime/vm/service/service.md
Perhaps this is what you are looking for
enum EventKind {
// Notification that VM identifying information has changed. Currently used
// to notify of changes to the VM debugging name via setVMName.
VMUpdate,
// Notification that a new isolate has started.
IsolateStart,
used with Events https://github.com/dart-lang/sdk/blob/master/runtime/vm/service/service.md#events
Related
I'm looking for ideas to send Docker Logs for each runs to be sent to my application in realtime. I'm looking ways this can be done. Please let me know how this can be done.
Let me know if you have done this already or know how this can be achieved. I want to build feature similar to Netlify or vercel where they show you all build log on UI in realtime. I want something similar for my node application.
You can achieve this with Vercel and Log Drains.
Log Drains make it easy to collect logs from your deployments and forward them to archival, search, and alerting services by sending them via HTTPS, HTTP, TLS, and TCP once a new log line is created.
At the time of writing, we currently support 3 types of Log Drains:
JSON
NDJSON
Syslog
Along with Log Drains, we are introducing two new open-source integrations with logging services for you to start using them today: LogDNA and Datadog.
Install the integration: https://vercel.com/integrations?category=logging
See the announcement blog post: https://vercel.com/blog/log-drains
Note that Vercel does not allow Docker deployments, but does support Serverless Functions.
I'm currently developing a Wolkenkit application which is run on my local machine.
I want to upload a file from the Wolkenkit app to the blob server (as documented here).
When sending a POST request from the server to https://local.wolkenkit.io:3001/, Node.js gives me the error ECONNREFUSED.
I've tested the POST-Request with another program and it works there. Any idea why it doesn't work from the wolkenkit application itself?
Thanks!
The Storing files sample you linked to shows code that is to be run in the browser, not in the backend itself. Of course, both should work, but there are a few minor differences you need to watch out for.
Fixing the host name
First, I suppose that local.wolkenkit.io in your case maps to 127.0.0.1, which is the default for wolkenkit. That means that when you try to connect to this domain from within a Docker container, the container does not try to call out to the blog storage container, but it stays within itself. So, the first thing that needs to be fixed is the host name.
Basically, there are two options for this: You can either setup local.wolkenkit.io so that it resolves to the external IP address of your machine. This would work, but is pretty cumbersome. The other option is to directly address the appropriate container that is responsible for blob storage, by its internal name. The internal name is <name-of-your-app>-depot-file. So you need to replace https://local.wolkenkit.io:3001/ by https://<...>-depot-file.wolkenkit.io:3001/.
Fixing the port
Second, the port is wrong. This is because the blob storage service is internally running on port 3000, externally on 3001. So instead of https://<...>-depot-file.wolkenkit.io:3001/ you need to use https://<...>-depot-file.wolkenkit.io:3000/.
Once you have done this you should not get any more errors like ECONNREFUSED, since now the service can be found.
Fixing SSL issues
Third, since you are now connecting to the blob storage service using a different domain name, the SSL certificate doesn't match any more, since it was issued for local.wolkenkit.io. As a result, you will get SSL errors when trying to connect.
The simplest way to get around this is to disable any SSL checks (albeit this is also the most insecure way to handle this!). How to do this depends on the HTTP client module you are using. E.g., in request there is an option called strictSSL that you can set to false.
Of course, what you actually should do is to either use a custom certificate which includes this domain name as well, or to write a function that handles the certificate check and accepts the presented one, especially in this case.
If you do all of this, things should work :-)
PS: I am one of the authors of wolkenkit. Thanks a lot for bringing up this issue, and we will take care of this in the future, to make storing blobs easier.
Since 12h the website (Wordpress website) that is hosted on Google Cloud Platform has a time out issue. After 60 seconds of trying to load the website, the following message appears "The connection has timed out".
When trying to connect with SFTP, same issue.
What should I do to resolve this?
Since two different services stopped to work at the same time it
sounds like a networking issue. There is a timeout, therefore there is the server not answering at all to the requests.
What to do?
I would proceed with this general troubleshooting steps, if you want you can upload your question with the result of these commands/question to proceed with the troubleshooting.
First of all I would check if you are able to ping the
external/public IP of the instance.
I would check if the firewall rules allows TCP80/TCP443 and TCP22, Notice that on GCP you need to create the rule and assign the TAG to the machine from its detail page if the the rule does not apply to the whole network.
Are you able to ssh into the instance?
I would check if the processes are actually listening netstat -tuplen
If you are able when logged into the machine do you have access to the internet? Are you able to ping external IP? If not whats about internal IP?
I would go to the "activity" page of your Google Cloud Console to check which actions have been taken while the instance was still running.
I would check as well the history of the Linux machine to check if you run some commands acting on the network configuration of the machine.
Note that if you cannot SSH into the machine you can always access through serial console setting a password for your username through a startup script.
UPDATE
I had the possibility to take a look into the project, the machine was stopped due to issue with the billing account (it was closed) after the free trial period ended.
I would suggest you to go again trough the documentation regarding the upgrade of the billing account
If you have still some doubts or question after you perform this operations you can file a case at this link with the billing team and they will help you to solve the issue.
I'm setting up an iOS app to use the IP Messaging and video calling apis. I'm able to connect, create channels and setup a video call if I manually create hard-coded tokens for the app. However, if I want to use the PHP server (as described here https://www.twilio.com/docs/api/ip-messaging/guides/quickstart-ios) then I always get an error and it can't connect anymore.
I'm attaching a screenshot of what I see when I hit the http://localhost:8080 address which seems to produce a 500 Internal error on this URL: https://cds.twilio.com/v2/Streams
Thanks so much!
After much time spent on this I decided to try the node backend instead - under other server-side languages of the PHP and I have it running in 2 minutes! I used the exact same credentials as the ones that I was using on the PHP config file so either my PHP environment has something strange or the PHP backend needs some fixing. In any case, I'm able to move forward using the node backend, so if you run into the same issue just try node instead of PHP. woohoo!
We use stateful DataSnap servers for some business logic tasks and also to provide clientdataset data.
If we have to update the server to modify a business rule, we copy the new version into a new empty folder and register it (depending on the Delphi version, just by launching or by running the TRegSvr utility).
We can do this even while the old server instance is running. However, after registering the new version, all new client connections will still use the currently running (old) server instance. All clients have to disconnect first, then the new server will be used for the next clients.
Is there a way to direct all new client connections to the new server, immediately after registering?
(I know that new or changed method signatures will also require a change and restart of the clients but this question is about internal modifications which do not affect the interface)
We are using Socket connections, and all clients share the same server application (only one application window is open). In the early days we have used a different configuration of the remote datamodule which resulted in one app window per client. Maybe this could be a solution? (because every new client will launch the currently registered executable)
Update: does Delphi XE offer some support for 'hot deployment' (of updated servers)? We use Delphi 2009 at the moment but would upgrade to XE if it offers easier implementation of 'hot deployment'.
you could separate your appserver into 2 new servers, one being a simple proxy object redirecting all methods (and optionally containing state info if any) to the second one actually implementing your business logic. you also need to implement "silent reconnect" feature within your proxy server in order not to disturb connected clients if you decide to replace business appserver any time you want. never did such design myself before but hope the idea is clear
Have you tried renaming the current server and placing the new in the same location with the correct name (versus changing the registry location). I have done this for COM libraries before with success. I am not sure if it would apply to remote launch rules through as it may look for an existing instance to attach to instead of a completely fresh server.
It may be a bit hackish but you would have the client call a method on the server indicating that a newer version is available. This would allow it to perform any necessary cleanup so it doesn't end up talking to both the existing server instance and new server instance at the same time.
There is probably not a simple answer to this question, and I suspect that you will have to modify the client. The simplest solution I can think of is to have a flag (a property or an out parameter on some commonly called method) on the server that the client checks periodically that tells the client to disconnect and reconnect (called something like ImBeingRetired).
It's also possible to write callbacks under certain circumstances for datasnap (although I've never done this). This would allow the server to inform the client that it should restart or reconnect.
The last option I can think of (that hasn't already been mentioned) would be to make the client/server stateless, so that every time the client wants something it connects, gets what it wants then disconnects.
Unfortunately none of these options are the answer you want to your question, but might give you some ideas.
(optional) set up vmware vSphere, ESX, or find a hosting service that already has one.
Store the session variables in db.
Prepare 2 web boxes with 2 distinct IP address and deploy your stuff.
Set up DNS, firewall, load balancer, or BSD vm so name "example.com" resolves to web box 1.
Deploy new version to web box 2.
Switch over to web box 2 using whatever routing method you chose.
Deploy new version to web box 1 if things look ok.
Using DNS is probably easiest, but it takes time for the mapping to propagate to the client (if the client is outside your LAN) and also two clients may see different results. Some firewalls have IP address mapping feature that you can map public IP address and internal IP address. The ideal way is to use load balancer and configure it to 50:50 and change it to 100:0 when you want to do upgrade, but it costs money. A cheaper alternative is to run software load balancer on BSD vm, but it probably requires some work.
Edit: What I meant to say is session variables, not session. You said the server is stateful. If it contains some business logic that uses session variable, it needs to get stored externally to be preserved across reconnection during switch over. Actual DataSnap session will be lost, so when you shutdown web box 1 during upgrade, the client will get "Session {some-uuid} is not found" error by web box 1, and it will reconnect to web box 2.
Also you could use 3 IP addresses (1 public and 2 private) so the client always sees 1 address , which is better method.
I have done something similar by having a specific table which held my "data version". Each time I would update the server or change a system wide global setting, I would increment this field. When a client starts it always checks this value, and will check again before any transactions/queries. If the value was ever different from when I first started, then I needed to go through my re-initialization logic, which could easily include a re-login to an updated server.
I was using IIS to publish my app servers, so the data that would change would be the path to the app server. I kept the old ones available, to respond to any existing transactions that were in play. Eventually these would be removed once I knew there were no more client connections to that version.
You could easily handle knowing what versions to keep around if you log what server the client last connected too (and therefore would know about).
For newer versions (Delphi 2010 and up), there is an interesting solution
for systems using the HTTP transport:
Implementing Failover and Load Balancing in DataSnap 2010 by Andreano Lanusse
and a related question for the TCP/IP transport:
How to direct DataSnap client connections to various DS Servers?