I think I found my issue with the mutable headers in question. It appears that the headers of a message are shared amongst the exchanges sent out in a multicast, so modifying a header in one route affects the other route. If that's not the case, then I've discovered some very strange behavior.
On 6 July 2016 at 20:34, Tadayoshi Sato <sato.tadayo...@gmail.com> wrote: > Hi, > > It's just an idea off the top of my head, but what about providing a parity > check header in company with the header you want to be immutable. I.e. > > YOUR_HEADER = "Do not change!" > YOUR_HEADER_MD5 = "fef4de21954d4b9f1b3e61ed153799da" > > or > > YOUR_HEADER_HASH = "md5:fef4de21954d4b9f1b3e61ed153799da" > > When making use of this header, you can always validate if it's not changed > in the routes. > > On Wed, Jul 6, 2016 at 6:03 AM, Matt Sicker <boa...@gmail.com> wrote: > > > Let me give a more specific use case. Path parameters from rest-dsl are > > passed in as message headers. I don't want any route to accidentally > > overwrite or modify those headers as they're useful for the entire > > lifecycle of that message. > > > > On 5 July 2016 at 16:00, Matt Sicker <boa...@gmail.com> wrote: > > > > > The exact use case is preventing developers from [inadvertently] > > modifying > > > headers or properties that are used before and after a particular > > subroute. > > > > > > On 5 July 2016 at 15:57, souciance <souciance.eqdam.ras...@gmail.com> > > > wrote: > > > > > >> I guess the question is, why would different routes split over > different > > >> bundles want to write over the same header/property? What's the case > > here? > > >> Surely it cannot be just to prevent accidents by developers because > what > > >> would be their reason to write over that header? > > >> > > >> I think it is better to agree on a naming and some sort of other > > >> convention > > >> and stick to that because I don't think there is a way to to make a > > header > > >> immutable. I guess an ugly solution would be to save the header in a > map > > >> and give the key name something very unique. > > >> > > >> On Tue, Jul 5, 2016 at 10:48 PM, Matt Sicker [via Camel] < > > >> ml-node+s465427n578481...@n5.nabble.com> wrote: > > >> > > >> > Please let me know if you think of anything! > > >> > > > >> > On 5 July 2016 at 15:16, Brad Johnson <[hidden email] > > >> > <http:///user/SendEmail.jtp?type=node&node=5784811&i=0>> wrote: > > >> > > > >> > > I certainly understand the impulse and think it is spot on but > can't > > >> > think > > >> > > of how to do it with headers. Claim checks might work but they > are > > >> > really > > >> > > for reducing overhead of data and not for locking like that but > that > > >> > might > > >> > > be a viable solution depending on the exact problem. > > >> > > > > >> > > Thanks Matt, this is going to be stuck in my head now. I'll > > probably > > >> > dream > > >> > > of an answer of some sort tonight. > > >> > > > > >> > > Brad > > >> > > > > >> > > On Tue, Jul 5, 2016 at 3:02 PM, Matt Sicker <[hidden email] > > >> > <http:///user/SendEmail.jtp?type=node&node=5784811&i=1>> wrote: > > >> > > > > >> > > > My use case is basically to help prevent bugs where a header or > > >> > exchange > > >> > > > property gets modified. Some of my routes in question branch out > > >> into > > >> > > > several different bundles, and it is difficult to enforce > > contracts > > >> > that > > >> > > > way amongst several developers with varying levels of Camel > > >> expertise. > > >> > > > Similar to how one might use final variables to prevent people > > from > > >> > > > reassigning them, this could be a final header that prevents > > people > > >> > from > > >> > > > reusing them for things. > > >> > > > > > >> > > > On 5 July 2016 at 14:22, Brad Johnson <[hidden email] > > >> > <http:///user/SendEmail.jtp?type=node&node=5784811&i=2>> > > >> > > > wrote: > > >> > > > > > >> > > > > That's what I figured. I'd have to look at the Map > > implementation > > >> > of > > >> > > the > > >> > > > > exchange but as far as I know there isn't a way to make it a > > write > > >> > once > > >> > > > > only operation. It's just a map of some sort. There might > be a > > >> way > > >> > to > > >> > > > do > > >> > > > > it with transactions but I'm not an expert there. I generally > > use > > >> > > > headers > > >> > > > > but in reality should probably be using exchange properties > more > > >> > often. > > >> > > > > > > >> > > > > > > >> > > > > > > >> > > > > > >> > > > > >> > > > >> > > > http://stackoverflow.com/questions/10330998/passing-values-between-processors-in-apache-camel > > >> > > > > > > >> > > > > Almost any mechanism I can think of off the top of my head > could > > >> be > > >> > > > > subverted by someone who wanted to or who didn't understand > that > > >> the > > >> > > > value > > >> > > > > associated with the bean shouldn't be modified. For example, > > you > > >> > could > > >> > > > > create a bean that you associate with your header that stores > > data > > >> > but > > >> > > > also > > >> > > > > returns a UUID. That UUID could be stored in another header > and > > >> > > sometime > > >> > > > > later in the routes you could verify that the bean stored > under > > >> your > > >> > > key > > >> > > > > returns the same UUID as the header indicates. But that > > wouldn't > > >> > stop > > >> > > > > someone from changing the bean stored to the key and it > wouldn't > > >> > > prevent > > >> > > > > them from updating the UUID to a new bean they might create. > > >> > > > > > > >> > > > > On Tue, Jul 5, 2016 at 1:49 PM, Matt Sicker <[hidden email] > > >> > <http:///user/SendEmail.jtp?type=node&node=5784811&i=3>> wrote: > > >> > > > > > > >> > > > > > I'm thinking of an idea to prevent a header from being > > modified > > >> by > > >> > > > other > > >> > > > > > parts of the route. A sort of contract if you will. > > >> > > > > > > > >> > > > > > On 5 July 2016 at 13:01, Brad Johnson <[hidden email] > > >> > <http:///user/SendEmail.jtp?type=node&node=5784811&i=4>> > > >> > > > > > wrote: > > >> > > > > > > > >> > > > > > > Is there another part of your process that is specifically > > >> > changing > > >> > > > the > > >> > > > > > > header or are you more concerned about it being > consistently > > >> > there > > >> > > > > across > > >> > > > > > > routes? Nothing will change it automatically if it is > your > > >> > header. > > >> > > > I > > >> > > > > > > don't remember the actual implementation but conceptually > it > > >> is > > >> > > just > > >> > > > a > > >> > > > > > > hastable/map with key/values. If you set header with some > > >> > specific > > >> > > > key > > >> > > > > > > then nothing else will change it. > > >> > > > > > > > > >> > > > > > > As an example, I use a camel splitter and then set a > header > > >> with > > >> > > the > > >> > > > > > > splitter index so that I can use it in another route later > > to > > >> > > > > reassemble > > >> > > > > > > with the resequencer. > > >> > > > > > > > > >> > > > > > > <split> > > >> > > > > > > <simple>${body}</simple> > > >> > > > > > > <setHeader headerName="seqnum"> > > >> > > > > > > <simple>exchangeProperty.CamelSplitIndex</simple> > > >> > > > > > > </setHeader> > > >> > > > > > > ... > > >> > > > > > > > > >> > > > > > > The "seqnum" is just a key that I'm defining. I could > > >> obviously > > >> > > call > > >> > > > > it > > >> > > > > > > anything "sequenceNumber" or whatever but when I access it > > >> later > > >> > > that > > >> > > > > > > header is available on the exchange. If I explicitly > change > > >> what > > >> > > the > > >> > > > > map > > >> > > > > > is > > >> > > > > > > storing for "seqnum" then it will be different because I > > can't > > >> > make > > >> > > > the > > >> > > > > > > header map itself immutable. > > >> > > > > > > > > >> > > > > > > > > >> > > > > > > On Tue, Jul 5, 2016 at 10:33 AM, Matt Sicker <[hidden > email] > > >> > <http:///user/SendEmail.jtp?type=node&node=5784811&i=5>> > > >> > > > wrote: > > >> > > > > > > > > >> > > > > > > > As in once I set the header, nothing can change the > header > > >> > during > > >> > > > the > > >> > > > > > > > lifecycle of the message during a route. Same for an > > >> exchange > > >> > > > > property. > > >> > > > > > > > > > >> > > > > > > > -- > > >> > > > > > > > Matt Sicker <[hidden email] > > >> > <http:///user/SendEmail.jtp?type=node&node=5784811&i=6>> > > >> > > > > > > > > > >> > > > > > > > > >> > > > > > > > >> > > > > > > > >> > > > > > > > >> > > > > > -- > > >> > > > > > Matt Sicker <[hidden email] > > >> > <http:///user/SendEmail.jtp?type=node&node=5784811&i=7>> > > >> > > > > > > > >> > > > > > > >> > > > > > >> > > > > > >> > > > > > >> > > > -- > > >> > > > Matt Sicker <[hidden email] > > >> > <http:///user/SendEmail.jtp?type=node&node=5784811&i=8>> > > >> > > > > > >> > > > > >> > > > >> > > > >> > > > >> > -- > > >> > Matt Sicker <[hidden email] > > >> > <http:///user/SendEmail.jtp?type=node&node=5784811&i=9>> > > >> > > > >> > > > >> > ------------------------------ > > >> > If you reply to this email, your message will be added to the > > discussion > > >> > below: > > >> > > > >> > > > >> > > > http://camel.465427.n5.nabble.com/Is-it-possible-to-make-a-message-header-or-property-immutable-tp5784800p5784811.html > > >> > To start a new topic under Camel - Users, email > > >> > ml-node+s465427n465428...@n5.nabble.com > > >> > To unsubscribe from Camel - Users, click here > > >> > < > > >> > > > http://camel.465427.n5.nabble.com/template/NamlServlet.jtp?macro=unsubscribe_by_code&node=465428&code=c291Y2lhbmNlLmVxZGFtLnJhc2h0aUBnbWFpbC5jb218NDY1NDI4fDE1MzI5MTE2NTY= > > >> > > > >> > . > > >> > NAML > > >> > < > > >> > > > http://camel.465427.n5.nabble.com/template/NamlServlet.jtp?macro=macro_viewer&id=instant_html%21nabble%3Aemail.naml&base=nabble.naml.namespaces.BasicNamespace-nabble.view.web.template.NabbleNamespace-nabble.view.web.template.NodeNamespace&breadcrumbs=notify_subscribers%21nabble%3Aemail.naml-instant_emails%21nabble%3Aemail.naml-send_instant_email%21nabble%3Aemail.naml > > >> > > > >> > > > >> > > >> > > >> > > >> > > >> -- > > >> View this message in context: > > >> > > > http://camel.465427.n5.nabble.com/Is-it-possible-to-make-a-message-header-or-property-immutable-tp5784800p5784812.html > > >> Sent from the Camel - Users mailing list archive at Nabble.com. > > > > > > > > > > > > > > > -- > > > Matt Sicker <boa...@gmail.com> > > > > > > > > > > > -- > > Matt Sicker <boa...@gmail.com> > > > -- Matt Sicker <boa...@gmail.com>
