My workflow needs to wait for either an email approval via Bookmark or a WCF approval via Receive, so I used a Parallel activity. The email approval works just fine but I am trying to test the WCF and cant figure out what URL to use in WCF test client to access the Workflow.
I would be grateful for any leads because I am very new to WCF and am not very sure how to go about solving this problem.
You are using workflow service and then your second receive activity must be correlate with your first one and cancreateinstance check box set to false and service contract name is same as first one.
When you generate proxy for the workflow service, operation method is available for call from client.
You can refer this article
http://www.codeproject.com/Articles/50820/Establishing-Correlation-Between-Multiple-RECEIVE
Related
Consider an architecture like this:
API Gateway - responsible for aggregating services
Users microservice - CRUD operations on the user (users, addresses, consents, etc)
Notification microservice- sending email and SMS notifications
Security microservice - a service responsible for granting / revoking permissions to users and clients. For example, by connecting to Keycloak, it creates a user account with basic permission
Client - any application that connects to API Gateway in order to perform a given operation, e.g. user registration
Now, we would like to use Camunda for the entire process.
For example:
Client-> ApiGateway-> UsersMicroservice.Register-> SecurityMicroservice.AddDefaultPermition-> NotificationMicroservice.SendEmail
We would like to make this simplified flow with the use of e.g. Camunda.
Should the process start in UsersMicroservice.RegisterUser after receiving "POST api/users/" - that is UsersMicroservice.RegisterUser starts the process in Camunda and how does this endpoint know what specific process is to run in Camunda?
What if the BPMN process in Camunda is designed in such a way that immediately after entering the process there will be a Business Rule Task that will validate the Input and if there is no "Name", for example, it will interrupt the registration process? How UsersMicroservice will find out that the process has been interrupted and it should not perform any further standard operation like return this.usersService.Create (userInput);
Should the call to Camunda be in the Controller or rather in the Service layer?
How in the architecture as above, make a change to use Camunda to change the default Client-> UsersMicroservice-> UsersService-> Database flow, adding e.g. input validation before calling return this.usersService.Create (someInput);
If your intention is to let the process engine orchestrate the business process, then why not start the business process first? Either expose the start process API or a facade, which gets called by the API gateway when the desired business request should be served. Now let the process model decide which steps need to be taken to serve the request and deliver the desired result/business value. The process may start with a service task to create a user. However, like you wrote, the process may evolve and perform additional checks before the user is created. Maybe a DMN validates data. Maybe it is followed by a gateway which lead to a rejection path, a path that call an additional blacklist service, a path with a manual review, and the "happy path' with automated creation of the user. Whatever needs to happen, this is business logic, which you can make flexible by giving control to the process engine first.
The process should be started by the controller via a start process endppoint, before/not form UsersMicroservice.RegisterUser. You use a fixed process definition key to start. From here everything can be changed in the process model. You could potentially have an initial routing process ("serviceRequest") first which determines based on a process data ("request type") what kind of request it is ("createUser", "disableUser",...) and dispatches to the correct specific process for the given request ("createUser" -> "userCreationProcess").
The UsersMicroservice should be stateless (request state is managed in the process engine) and should not need to know. If the process is started first, the request may never reach UsersMicroservice. this.usersService.Create will only be called if the business logic in the process has determined that it is required - same for any subsequent service calls. If a subsequent step fails error handling can include retries, handling of a business error (e.g. "email address already exists") via an exceptional error path in the model (BPMNError), or eventually triggering a 'rollback' of operations already performed (compensation).
Controller - see above. The process will call the service if needed.
Call the process first, then let it decide what needs to happen.
When building an application before scaling to multiple micro services. You have a codebase consisting of services that are decoupled. IE a services no longer depends on another service, not even loosely via a interface. It receives input from a service via a message buss. It has a method receivePaymentRequest but its callee is not the Order service. Its invoked via the message bus, perhaps in the future on another server. But imagine theres no need to run multiple servers at this point.
a order services posts to the message bus payment-request event
the payment services picks up on this message
payment is completed
payment service send a payment-complete event message to the message bus
the order service picks up this message
I"m not thinking about the patterns that enable this to be fault tolerant. But instead when to use this approach since it adds a lot of complexity. So please ignore what i've left out with regards to this
Correct? Is it stupid to implement it like such before scaling to microservices. How does this. Is SOA the step before actual microservices?
When should a class receive/publish on the message buss and when should it depend on a service as a class (even injected via a interface) ?
I have an application that is creating StreamingSubscription (using EWS managed API) for many hundreds of room resource mailboxes in EXO, and I'm trying to make the code tolerant of a subscription going "bad" and needing to be re-created. Here's the behavior I'm seeing at the moment.
I first divide up the mailboxes into groups according to best practices, and then within each group:
I create a StreamingSubscription for each mailbox
I add all the subscriptions to a connection and open the connection
Some time passes, and the OnSubscriptionError event fires for
one subscription. At this point I find that the subscription in
question is no longer in the connection's CurrentSubscriptions
collection, but I'm able to identify which mailbox it was originally
for.
I then flag that mailbox so that the code will try to re-create its
subscription.
When the code tries to re-create the failed subscription, this error is thrown:
Request failed because EWS could not contact the appropriate CAS server for this request.
Thereafter, my code tries again once per minute to create that subscription, and that same error is thrown each time. This continues for as long as I allow it to run.
If I then stop my Windows service and start it again, all the subscriptions are created successfully, including that failed one.
Here's my question. Why is it able to successfully create the subscription after stopping and re-starting the service, but can't re-create it after the OnSubscriptionError?
I'm new to WF. what I'm trying to do is to create a simple Workflow Service and Call them in various clients. So what i have done, I have created a Workflow service. It has a xamlx file and that has a sequence with Receive and Send Reply activity. I also have Correlations. So the first ReceiveandSendReply activity has CanCreateInstance True. In addition to this I
wrote some of my own code activities.
Now I have hosted this service is IIS and trying to call this service using a console app. I have added the web Reference and created a service client and passed the values to the service. It gives me expected results.
But when I'm trying to run another client at the same time it gives me Instance error. I think the Workflow is not initiating a new Instance for the second client.
So I did a search and found multiple instancing can be achieved by using workflowservicehost. But could not find a way to do it.
I think the way Im calling the service is not correct. I'm just creating a new object from the service reference and calling the operation.
Can anyone help me with this?
Please have a look at correlation rules you've set up for your workflow. If several clients passes parameters which correlate with the same instance - a new instance won't be created.
So, if you need a new instance you either need to set different correlation rules, so that different client's calls would correlate with different workflow instances.
So what I need is a kind of a push and pull web service mechanism; Certain devices will be sending data to my parse backend and some others should be able to receive the newly added data as it's being added. Think of it as a restaurant environment where customers send their order via their phones and the restaurant manager receives the orders on his pc real time.
I know I can use push notifications but I want to target specific users (in this case the manager alone). I guess I can have a specific push notification channel in which only the manager is added, but I am not sure if I can send proper json data in bulk or just simple strings. Maybe there's a smarter way of going about it.
Any suggestions?
Many thanks,
Polis
You can use the Parse Cloud for this purposes. So certain devices (you can differentiate in cloud or in client side) can call the cloud method. The called cloud method can make http request to your server (manager pc real time). From now on your server side can deliver coming message to your manager in real time. In this solution, I assume that you have your own server for web users (like manager) and mobile application for client user (customers).
Hope this can give you an idea. Regards.
You can use Push notification for this purpose. In my opinion that would be your best option.
When registering for push notification on client side, you can set a column owner to user pointer. Now when sending push notification from one user to another you can query the Installation class for other user's pointer. You can send push notification either from client side or writing cloud code for afterSave trigger. Cloud code is a better option.
The downside of this approach is that if other user did not allow push notifications then this would fail. The second user would still be able to get the data when they open the app, but won't get push notifications.
***I built a chat app using this approach on Parse.com
You don't need a complicated channel setup, before you save your installation, do a line like this:
[installation setObject:[PFUser currentUser] forKey:#"owner"];
[installation saveInBackground]; // ... completion or whatever
Then, just query:
PFQuery *installationQuery = [PFInstallation query];
[installationQuery whereKey:#"owner" equal:userImLookingFor];
Then, it's like PFPush w/ query or something.
(I'm typing from memory, so some of these might need to be slightly tweaked)