Usually we deploy BPEL business processes on Apache ODE or WSO2 BPS Server included in Tomcat server, can I deploy a business process on Google App Engine's Web Server? Actually I haven't any idea about that!
There is a lot more to running a BPEL process than it seems. You would not deploy the BPEL process, you would deploy Apache ODE to Google App Engine.
Unfortunately, last I checked App Engine has stringent restrictions on the number of threads a program can spawn, making Apache ODE unusable (see 0(their doc)):
The secured "sandbox" environment isolates your application for service and security. It ensures that apps can only perform actions that do not interfere with the performance and scalability of other apps. For instance, an app cannot spawn threads in some ways, write data to the local file system or make arbitrary network connections. An app also cannot use JNI or other native code. The JVM can execute any Java bytecode that operates within the sandbox restrictions.
you can't. See Google app engine's documentation.
[1] https://developers.google.com/appengine/docs/
[2] https://developers.google.com/search/results?q=BPEL&p=%2Fappengine
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Our project was running in GCP compute engine. For scaling purpose, it is moved to app engine. We had rabbitmq implemented for push messages and chatbots in compute engine. In app engine it is not feasible to implement rabbitmq. So I was going through alternate options. There I found cloud task option. But I have doubts in certain areas even after reading their documentation
In my understanding, we need an app engine instance for cloud tasks. In that case, can I implement it in same project itself as a different service? Will this affect the performance of the existing project?
Is there any better solution than cloud tasks in this case?
You can implement additional services under your app in the App Engine as shown in this diagram.
By default, App Engine scales your app to match the load. Your apps will scale up the number of instances that are running to provide consistent performance, or scale down to minimize idle instances and reduces costs.
You can consider running a RabbitMQ Cluster on Google Kubernetes Engine. You can find more information in the following documentation: rabbitmq.
I am trying to run google app engine with memcache locally with go run *.go and I am getting the following response:
service bridge HTTP failed: Post http://appengine.googleapis.internal:10001/rpc_http: dial tcp: lookup appengine.googleapis.internal: no such host**
What is the proper way to run locally?
The library that you are trying to use is a App Engine standard environment library that is not available in the flexible environment. The flexible environment is built on top of Compute Engine and a very different system. You could try using MemoryStore for Redis. You also might be able to break your application into microservices. An App Engine project can have services on different runtime environments (mix of flex/std, mix of languages), but you'll have to be careful about how you communicate and work across the services. Its not necessarily a trivial thing to rearchitect your app though.
I have a job that involves continuously listening to one or more websocket/mqtt feeds and forwarding this data to an event queue. This job is written in javascript and would run 24/7 in a continuous loop.
The most obvious solution is to run this job on a VM with Compute Engine, but I was wondering is there is a more elegant solution. Azure, for example, has WebJobs that's well-suited to this kind of task. It even restarts the script if there is an error.
Is there some other component on GCP that can run this job in a "managed" way?
Google Cloud does not have a product similar to Azure WebJobs at the moment. Both the standard and flexible environments of Google Cloud App Engine do not currently support websockets. In order to use websockets you can use Compute Engine or Kubernetes Engine.
I was able to create the basic 'hello world' program.
When I tried to understand the difference between a cloud and a server I learned that Cloud is where you have an access to virtual instance created exclusively for you and you are free to choose and install software of your choice.Why Google App Engine(GAE) is used widely where as tomcat is not used. What are major differences between GAE and Tomcat?
Cloud is Google Cloud Platform at this case. App Engine is just one of their services.
App Engine is a platform to build your apps on top of it. A Platform As A Service or PaaS. It simplifies the process of building a scalable application, and you should use it when you understand what you really need and understand principles of scalable application.
Tomcat is a Java web container, and there're many alternatives. Google App Engine is using Jetty. You could actually use it with Tomcat by using Flexible VM, though it doesn't make much sense.
App Engine is not about web server, it's a set of services that helps you to build a scalable app. It includes Memcache, Datastore, Task Queue, Images API, deployments tools and versioning, CDN for static files, and most important automatic scale.
Actually you aren't limited to App Engine on Google Cloud Platform. There is more traditional service, like own server in the cloud, called Compute Engine. There you can run your Tomcat or anything else.
I am pretty new to this whole idea of cloud and started of with Google app engine. I was able to create the basic 'hello world' program.
When i tried to understand the difference between a cloud and a server I learned that Cloud is where you have an access to virtual instance created exclusively for you and you are free to choose and install software of your choice.
But I don't see such an option with Google-cloud/app-engine. What if I have a tom-cat based application server which I would like to deploy on a cloud? Will Google app engine be of any help or should I try other cloud service providers such as Amazon EC2, hp cloud etc?
/DJ
The cloud type that you are referring to is called Infrastructure as a Service cloud.
OTOH, Google App Engine is Platform as a Service cloud.
The difference is that IaaS are a bunch of virtual machines that you need to setup yourself (OS + app stack), while PaaS typically comes with it's own API, where you write your app against the API and the rest (sw stack + scalability) is taken care of.
AppEngine comes with it's own servlet container (Tomcat is also a servlet container), so from this standpoint you could use your code on AppEngine. But the problem lies elsewhere: AppEngine imposes a set of limitation on the apps:
app must use GAE provided databases.
app can not write to filesystem
app can not have listening sockets
requests must finish in 60 seconds (e.g. no Comet or WebSockets -> no push)
You might want to review the FAQ.
To add to Peter's excellent answer, note that Google also has an IaaS service called Google Compute Engine.
Regarding other cloud query-
Before you start with cloud you might once try other options. Currently deploying application in almost all services are very easy.
few of them are-
Jelastic , Heroku , rackspace , nimbus , openshift etc.
Difference between cloud and server is very well explained already.
Since you mentioned about tomcat based application , I have worked with Jelastic for the same and found very easy to implement.
http://jelastic.com/docs/tomcat
http://jelastic.com/tomcat-hosting
Try all possible option , it will help you more .