Is it possible a service to call client after 4 -5 days when client is offline? e.g.
1. The client request some reports through service.
2. Service updates database with client request.
3. Offline work is done on the request
4. Report is uploaded to the database.
Can we service call its client and send report as soon as report is uploaded to database?
Can WCF duplex service be used to call client when client is offline?
Yes. WCF can be configured to use MSMQ as a transport. MSMQ is the only WCF transport that allows for all three:
disconnected scenarios
resume when computer becomes online and
optionally provide a level of guaranteed delivery
MSDN:
If you need to support disconnected queuing, use netMsmqBinding. Queuing is provided by using Microsoft Message Queuing (MSMQ) as a transport, which enables support for disconnected operations, failure isolation, and load leveling. more...
Essentially you invoke a WCF method (send a MSMQ message) and it will be delivered when the computer comes on-line again. Assuming you have set the appropriate expiration options.
Related
All ,
I have a doubt on the Request response pattern... Assume the following is my scenario
1.I have a service running on Windows Azure. This service can be called by users to execute a command.
2.I have a client applications that is running on my intranet. This client application will execute the command . The computer in which the client application is running is connected to internet , but does not have a static IP i.e machine cannot be accessed directly via the internet
3.I am planning to use Azure Service Bus through which my service on Windows Azure can communicate with the client application to execute....
In this scenario, can i use Request/response messaging i.e can the service post a message and expect a response from the client
OR
Should i use command queue for each client , the Service will push the command to be executed on a queue , the client will poll the queue and execute a command
Any help is appreciated
Since you are using WCF (based on the tag), you should consider using Service Bus Relay calling the WCF service asynchronously.
I assume you want to use Relaybinding here, using WCF.
Your web service (which is behind NAT, firewall devices, etc) is only opening outbound connections in that case. The service is listening on a registered endpoint in the cloud (that is accessible for him, because of credentials and protocol). All incoming service calls are sent over that port/socket. The response will then be sent back over the outgoing port again.
If the IP Address of your service changes, it wil register itself again (by listening on the same registered endpoint) and you can reach that service transparantly.
Another way you can achieve request/response in an asynchronous fashion, is through queues. This does not require any open connection between your client and your service and can happen fully asynchronous. This can be achieved by sending a message to the request queue for your specific service (with a Correlation Id). And when that service has processed that message, it can send the response to the response queue of your application, using sessions. A good example of this pattern can be found on Alan Smith's blog: http://www.cloudcasts.net/devguide/Default.aspx?id=13051
I'm building a system where several clients are connected to a central server by WCF using duplex MSMQ (updates are sent to the server, messages are periodically pushed out to several clients).
How do I best secure this scenario? The nature of duplex WCF effectively makes each client a server. Does that mean to secure each channel every client needs to shell out $1200 for a verisign cert?
Because MSMQ binding uses regular MSMQ queues, you can implement security using the standard MSMQ queue security model. You need to make sure you set security mode to 'Transport', and then allow or restrict access to the queue as appropriate.
When you create a queue you can set permissions which govern who can send, receive, or remove from the queue using active directory or Windows accounts. The only resource I can find with a few minutes googling is MSMQ for .NET Developers - describes a little about setting permissions.
Have a read of Securing Messages with Transport Security and the examples in the NetMsmqBinding documentation.
So you should either run your services as the same user, or ensure all the users are in a single AD group, etc and then grant queue permissions (send permission?) to that user / group only.
I have a wcf service and handle a lot of client (server document generation). This service should receive a lot of request and should be handle in queue. It also have a callback. (callback will return successfully generated document). I am still using PIA and will implement OpenXML in the future.
Is it wcf msmq is the way to implement this?
Is there any samples might be related? Previously its running in local machine but now want to change it as a so called "Server generated"
WCF MSMQ doesn't support callback directly - it supports only one-way operations. But for example this article discuss how to add this support. With default configuration you can send message back to original sender but it is not a callback. To support responses every client will have to expose queue and pass address of its queue as part of the request to be able to receive the message from the service. More about responses in MSMQ is in MSDN magazine.
I am developing a generic logging object which will be used within all of our future applications. It will submit a log to MSMQ, which will then asynchronously send it off to our server that will log that message to a database.
Currently I am trying to understand the architecture of how this will work. On the client side, once a log is submitted to MSMQ, will MSMQ then submit the log to WCF to send off to the server (which I assume will have another WCF endpoint receiving the messages)? Basically, I am asking what is the order of services that the log will travel through? I have read about netMsmqBinding for WCF, is this what I will need in order to send a log from MSMQ to WCF, and then I can use a basicHttpBinding to send it from WCF to WCF on the server side?
Something like:
[Client application] -> Logger -> MSMQ -> WCF ----------> [Server] WCF -> DB
WCF has netMsmqBinding that can handle both client and server messaging. If you use it MSMQ will be almost invisible to you. You will send message to WCF service, it will be put to MSMQ and server-side WCF will pick it and invoke method like with any other binding.
If you have any experience in creating WCF service you should do the same but also create MSMQ Queue.
Here are useful links: http://sukasom.wordpress.com/2008/08/18/wcf-and-msmq-part-1/, http://msdn.microsoft.com/en-us/library/ms752217.aspx
When one of clients changes some data on server I need to send a message from WCF service to all clients that makes them to download changed data. How can I make that?
You are looking for Publish-subscribe message exchange pattern where all client first have to register on the service (subscribe) when service receives new data it sends them to all other clients (publish).
WCF support this when using duplex communication - Net.Tcp or WSDualHttpBinding. You can check complex artice by Juval Lowy in MSDN magazine.