Cloud Native, Big/Fast Data, Containers. AWS, Azure and GCP certified..
German only. Heute exklusiv auf deutsch ein Artikel den ich für das DOAG Magazin im Früjahr 2011 geschrieben habe:
Download: Oracle Fusion Middleware und WebLogic Server in der Cloud (PDF)
Teile des Artikels sowie zahlreiche Grafiken sind aus meinem “Middleware and Cloud Computing” entommen. Viel Spaß beim Lesen!
An interesting question popped up on my Oracle Middleware and Cloud Computing book site which I like to answer here for the benefits of all the others puzzling at similar integration questions. In the context of using JMS as an integration technology I’d like to summarize the usage scenarios for Oracle WebLogic JMS Store-and-Forward and JMS-bridges (both are included in WebLogic server).
Hi Frank – [ …] We have a requirement to build 2-way asynchronous integration between an application running on WLS in AWS and a legacy J2EE app running on IBM WebSphere in our Data Centre. From your excepts my understanding is that SQS is intended for use only between AWS apps – is this correct ? I think we need to be looking at a full JMS solution for our integration – perhaps using WLS JMS Store-And-Forward – Thanks, Peter D
Hi Peter,
Based on your comment I cannot go into great detail or even provide a solid architecture that anwsers you question (one that will save you from more reading) but here are some important points to consider:
– Amazon’s SQS is not restricted to be only used from AWS instances. SQS is purely based on web services (or language bindings that encapsulate those WS calls) so you can use it from any computer. E.g. you can read or write to SQS queues from remote.
– WLS Store-and-Forward (SAF) can only couple WLS instances of the same version and does not bridge to other JMS providers. You cannot use SAF to transfer from WLS JMS to IBM MQSeries (or whatever Websphere might use). JMS is a pretty bad integration technology which requires to have the right messaging classes in your classpath. E.g. when writing messages from Websphere to a WebLogic JMS queue you are required to have the WLS JMS classes in Websphere classpath.
– You can use the WebLogic’s JMS bridge to solve the somehow messy classpath issues. WLS JMS bridge has to be deployed as JCA adapter (still the jar file from the other provider is required but it is not used in custom code). The bridge will automatically forward from e.g. WLS JMS to MQSeries and even supports transcations. However there is no support to bridge between WLS JMS and AWS SQS.
– Unlike let’s say Oracle Service Bus, if you are looking at Apache Camel there is support to convert incoming JMS messages to outgoing SQS. Note to Oracle’s product manager of OSB: we would appreciate to have SQS as a supported transport protocol or possibly as an SOA Suite JCA adapter. Thanks for considering it 🙂
regards,
Frank
When designing your cloud architecture sooner or later the question about the database will arise. Today Amazon Web Services announced the availability of Oracle database instances provisioned with the AWS Relational Database Service (RDS). However, there are many other options available, and in order to make an informed decision as to which will best suit your architecture, you should know the pros and cons of at least four:
I summarized my view in a detailed 12 page whitepaper (the weather here is too nice and I can’t bother myself putting all the screen shots into this blog posting).
The PDF describes all the details of RDS and compares them to the other options available. Also learn how to use WebLogic with RDS:
Cloud Databases and Oracle Whitepaper.
UPDATE: As of Aug/2012 there is support for APEX, Oracle XML DB and VPC now!
If you like to know more after reading the whitepaper have a look at my Oracle Cloud Computing book at Amazon and join the book’s Facebook site!
Amazon’s Simple Queue Service (SQS) is a cloud service for reliable messaging. The SQS service with its queues is located off-host. So, similar to the elastic load balancing service, or the relational database service, you can use the service without having to start an EC2 instance.
SQS is available in all four AWS regions with the same pricing. All regions are independent of each other so messages can never be in-between regions. Queue names have to be unique per region.
|
Highly available |
Queues are highly available: Messages waiting in queues for their delivery are stored redundantly on multiple servers and in multiple data centers.
|
Unlimited |
There is no limit for the number of messages or the size of a particular queue. One message body can be up to 64 KB of text in any format (default is 8KB). For larger messages you have to store the message somewhere else reliably, e.g. in S3, SimpleDB or RDS, and pass around a reference to the storage location instead of passing the message itself.
|
Message expiry |
When a message remains in a queue (because there is no receiver removing the message from the queue), the message expires after a default of four days (or a configurable maximum of 14 days).
After receiving a message from a queue, the message is locked for a configurable timeout. While the message is locked it is invisible to other receivers. SQS uses this mechanism to ensure that messages are delivered once.
It’s the receiver’s responsibility to explicitly delete the message when it is processed successfully. If the receiver fails before it is able to delete the message, then the message becomes visible again after the timeout, and another receiver can receive it.
Access to queues is restricted to the AWS account owners, but you can specify in an access policy statement that a queue will be shared.
|
No |
Encryption is not a built-in SQS feature, but depending on your privacy requirements you can consider encrypting the content of your message at an application level. Also, there is no built-in compression feature, but you can compress large messages at an application level before sending them.
|
At least once |
The message delivery semantic is engineered to be “at least once”. This means your applications have to cope with message duplicates.
Access to SQS is purely programmatic. Currently, there are no command-line tools from AWS, and there is no integration for SQS into the AWS management console yet.
There are language bindings for Java, PHP, Perl and C#. Also, the Java Typica library supports SQS.
SQS is ideal for decoupling systems or applications running on EC2. From a design perspective, SQS has many features in common with JMS queues. The most important differences between SQS and JMS queues are listed in Table 1.
Table 1: SQS Comparison with WLS Queues
| SQS Queues | WebLogic JMS Queues | |
| Max queue size | Unlimited | Limit depends on JVM heap and persistent store |
| Best Quality of Service | At least once | Exactly-once with transactions |
| Configurable retries | No | Yes |
| Persistence | Always | Optional |
| Scalability | Inherent | With distributed queues |
| Availability | Inherent | Whole-server migration
or JMS service migration |
| Message Order | Not guaranteed | Can be enforced even for distributed queues |
| Configurable quotas | No | Yes |
| Configurable flow control | No | Yes |
| Auto acknowledge | No | Yes |
| Time To Live configuration | 1h to 14d | 1 ms to ca. 2 mio years |
| Max message size | 64 KB | Unlimited, default is 10,000 KB |
| Compression | No | Yes |
| Billing | Free usage tier, then charged per request and data transfer amount | Included with WLS |
To conclude, SQS is an AWS cloud service that could replace WebLogic JMS queues.
Compared to JMS queues, SQS has fewer features, no auto acknowledgement of messages and no support for exactly-once message delivery. The advantage of SQS over JMS queues is SQS’ inherent availability, the virtually unlimited storage for messages and the zero configuration.
The inherent availability is an especially important factor to consider when deciding between SQS or JMS queues, because the built-in features offered by WebLogic for achieving availability of JMS are restricted in today’s clouds.
SQS is implemented off-instance; therefore, its availability is not affected if a particular EC2 instance becomes unavailable.
|
SNS |
Interestingly, there is a cloud service for the counterpart to JMS topics as well. The AWS Simple Notification Service allows you to send messages to more than one receiver using transport protocols such as HTTP, email and even SQS.
|
SQS vs. OSB |
In case you are wondering how this relates to Oracle Service Bus: Comparing SQS with Oracle Service Bus is like comparing apples with oranges, because in addition to the built-in JMS, service bus also supports protocol adaption, message flows with content-based routing, and most importantly, it is configuration driven.
In a nutshell: SQS is a queue service for the AWS cloud to decouple systems with message passing. As a cloud service it abstracts the Java EE specific details of JMS – nevertheless SQS is specific to AWS. Currently there is no cloud messaging service offered for the Rackspace cloud. Using an AWS specific service like SQS increases the effort to migrate to another cloud provider (and limits your possibilities to quickly switch to another cloud provider as a part of a contingency plan).
There is a free usage tier for up to 100,000 requests per month. Beyond that, Amazon adds $0.01 per 10,000 SQS requests to your bill.
In addition, you have to pay for the data transfer as shown the figure below. Only data transferred between SQS and EC2 within a single region is free. Data transferred between different regions will be charged at Internet data transfer rates on both ends.
I will offer a number of courses and workshops during the following weeks in right in the center of Munich. As usual all course dates and details will be announced on my mailing list. Right now it is the perfect time to subscribe to the mailing list if you haven’t done yet (there is approx. 1 announcement per quarter, of course you can unsubscribe any time).
The following courses are planned:
Feel free to contact me directly for other trainings or different locations (all courses are available word-wide),
have a great week!
Oracle WebLogic Server 12c Book
Oracle Middleware and Cloud Computing Book